CN109818567B

CN109818567B - Parallel or series connection type turn-off system for photovoltaic module

Info

Publication number: CN109818567B
Application number: CN201711149174.4A
Authority: CN
Inventors: 张永; 胡晓磊
Original assignee: Fonrich Shanghai New Energy Technology Co ltd
Current assignee: Fonrich Shanghai New Energy Technology Co ltd
Priority date: 2017-11-18
Filing date: 2017-11-18
Publication date: 2021-05-14
Anticipated expiration: 2037-11-18
Also published as: CN109818567A

Abstract

The invention mainly relates to a parallel or series connection type turn-off system for photovoltaic modules. The shutdown device is used for shutting down the corresponding photovoltaic assembly and removing the corresponding photovoltaic assembly from the battery string or recovering the corresponding photovoltaic assembly from the shutdown state to the serial connection state of the connected battery string, the shutdown control module stops transmitting a periodic excitation pulse source to each shutdown device to stop supplying power to a processor carried by each shutdown device when receiving a shutdown command, and the processor detects the power supply stopping condition and executes shutdown operation to shut down the respective corresponding photovoltaic assembly of the shutdown device; or when the turn-off control module receives the starting command, the periodic excitation pulse source is transmitted to each turn-off device again to restore the power supply to the processor carried by each turn-off device, and the processor detects the power restoration condition and executes the turn-on operation so as to restore the photovoltaic modules corresponding to the turn-off devices to the series connection state from the turn-off state.

Description

Parallel or series connection type turn-off system for photovoltaic module

Technical Field

The invention mainly relates to the technical field of solar power generation, in particular to a system capable of quickly switching off a series-connected multi-stage photovoltaic module.

Background

The photovoltaic power generation system needs to meet the safety standard in a power electronic system, and corresponding laws and regulations are provided for governments or related institutions of various countries. Based on safety code considerations, the american fire protection association modifies national electrical codes, requiring that in residential photovoltaic power generation systems: when an emergency occurs, the voltage of the direct current end is limited not to exceed eighty volts to the maximum extent after the alternating current grid-connected port of the photovoltaic power generation system is disconnected. Italian safety regulations caution: firefighters are absolutely not allowed to perform a fire extinguishing operation with a building charged with voltage. Germany also has first implemented fire safety standards and also stipulates in plain text: an additional direct current cut-off device needs to be added between an inverter and a component in the photovoltaic power generation system. From these laws and regulations, the first remarks to safety factors can be concluded: even if the photovoltaic modules have unexpected fire, the rescue is allowed to carry out fire-fighting rescue only after all the photovoltaic modules are burnt out and the personal safety is no longer endangered.

The popularity of the photovoltaic power generation system is higher in Europe and America, so that the matched rule and rule of safe power utilization also extend to the field of photovoltaic power generation in time. Taking the safety code NEC2017 in the united states as an example, the photovoltaic power generation system is required to have a rapid turn-off function, and the voltage between the conductors inside the photovoltaic array and between the conductors and the ground must not exceed about eighty volts at most after turn-off. The positive measures of the photovoltaic power station in dealing with the safety regulations are as follows: in order to realize quick switching-off, a switching-off device which plays a role in switching-off is specially installed at the output end of a photovoltaic module, a command transmitting device is installed on a battery pack string which provides direct current or a direct current bus, and the command transmitting device is mainly powered by an alternating current power grid. For example, in case of fire, it is necessary to turn off the photovoltaic module quickly, and the command transmitting device is used to instruct the turn-off device to turn off. The countermeasure of shutting down the photovoltaic module can prevent further deterioration of negative events such as fire and the like, and improve reliability and safety.

Disclosure of Invention

In one non-limiting alternative embodiment of the present invention, a parallel shutdown system for photovoltaic modules is disclosed and generally comprises:

at least one turn-off control module;

the photovoltaic module comprises a plurality of turn-off devices and a plurality of photovoltaic modules, wherein each photovoltaic module is provided with one turn-off device;

a plurality of photovoltaic modules are connected in series to form a battery pack string;

each turn-off device is used for turning off the photovoltaic component corresponding to the turn-off device to remove the photovoltaic component from the battery string or restoring the photovoltaic component corresponding to the turn-off device from a turn-off state to a series connection state of connecting the photovoltaic components into the battery string;

when the turn-off control module receives a turn-off command, the turn-off control module stops transmitting a periodic excitation pulse source to each turn-off device to stop supplying power to a processor of each turn-off device, and the processor detects the condition of stopping supplying power and executes turn-off operation so as to turn off the photovoltaic components corresponding to the turn-off devices; or

When the turn-off control module receives the starting command, the periodic excitation pulse source is transmitted to each turn-off device again to restore the power supply to the processor of each turn-off device, and the processor detects the power restoration condition and executes the turn-on operation so as to restore the photovoltaic modules corresponding to the turn-off devices to the serial connection state from the turn-off state.

The above parallel shutdown system for photovoltaic module, wherein:

each turn-off device comprises a group of input ends respectively connected to the positive electrode and the negative electrode of the photovoltaic assembly and a group of output ends connected with other turn-off devices in series, and a bypass diode is arranged between the group of output ends of each turn-off device;

when the photovoltaic component is turned off, the bypass diode provides a conduction path between a group of output ends of the turn-off device corresponding to the turned-off photovoltaic component.

The above parallel shutdown system for photovoltaic module, wherein:

each turn-off device comprises a main switch for switching off or on between an input and an output thereof, the main switch having a first terminal, a second terminal and a control terminal;

each turn-off device comprises a first coupling transformer coupled to the output end of the turn-off device through a power line, and a primary winding of the first coupling transformer and a first terminal of the main switch are connected to one of a group of output ends;

the secondary winding of the first coupling transformer is used for extracting an excitation pulse source loaded on the power line;

the induced excitation pulse source charges an energy storage capacitor connected between a preset reference terminal and the first terminal through a steering diode;

the processor detects the potential of the energy storage capacitor, the main switch is controlled by the processor to be switched off when the processor detects the power supply stopping condition, or the main switch is controlled by the processor to be switched on when the processor detects the power supply recovering condition.

The above parallel shutdown system for photovoltaic module, wherein:

and a parallel resistor connected in parallel with the energy storage capacitor is also arranged between the preset reference terminal and the first terminal.

The above parallel shutdown system for photovoltaic module, wherein:

and a pair of reverse series-connected voltage stabilizing diodes connected in parallel with the energy storage capacitor is also arranged between the preset reference terminal and the first terminal.

The above parallel shutdown system for photovoltaic module, wherein:

the synonym terminal of the secondary winding of the first coupling transformer is coupled to the first terminal of the main switch;

the dotted terminal of the secondary winding of the first coupling transformer is coupled to a preset reference terminal through the steering diode;

the homonymous terminal is connected to the anode of the steering diode and a preset reference terminal is connected to the cathode of the steering diode.

The above parallel shutdown system for photovoltaic module, wherein:

the dotted terminal of the secondary winding of the first coupling transformer is coupled to a first node through a first capacitor;

a first diode is connected between the synonym end of the secondary winding of the first coupling transformer and the first node;

the anode of the first diode is connected to the synonym terminal of the secondary winding of the first coupling transformer, and the cathode is connected to the first node;

the first node is connected to the anode of the steering diode and the predetermined reference terminal is connected to the cathode of the steering diode.

The above parallel shutdown system for photovoltaic module, wherein:

the turn-off device comprises a parallel capacitance connected between the first and second terminals of the main switch;

after the turn-off device performs the turn-off operation and closes the main switch, a parallel capacitor connected in parallel with the main switch provides a conduction path through which the excitation pulse source propagates bypassing the main switch.

The above parallel shutdown system for photovoltaic module, wherein:

the turn-off device comprises a normally-open parallel switch connected between a first terminal and a second terminal of the main switch, and a control terminal of the normally-open parallel switch is connected to a preset reference terminal;

after the turn-off device executes turn-off operation and closes the main switch, the normally-open parallel switch entering the conducting state provides a conducting path for the excitation pulse source to propagate by bypassing the main switch; and

when the processor detects the power supply recovery condition and switches on the main switch, the potential of the energy storage capacitor also controls the normally open parallel switch to be cut off.

The above parallel shutdown system for photovoltaic module, wherein:

the turn-off device comprises a main switch for switching off or on between an input end and an output end of the main switch, wherein the main switch is provided with a first terminal, a second terminal and a control terminal;

the turn-off device comprises an inductor coupled to its output terminal by a power line, one end of the inductor being connected to the first terminal of the main switch at one of a set of output terminals, the opposite end of the inductor being connected to the anode of a steering diode and the cathode of the steering diode being coupled to a predetermined reference terminal;

the inductor is used for extracting an excitation pulse source loaded on the power line;

the induced excitation pulse source charges an energy storage capacitor connected between a preset reference terminal and the first terminal through the steering diode;

In one non-limiting alternative embodiment of the present invention, a series shutdown system for a photovoltaic module is disclosed and generally comprises:

at least one shutdown control module and at least one shutdown device;

a plurality of photovoltaic modules are connected in series to form a battery string and are also connected in series with a turn-off device;

the turn-off device is used for performing turn-off operation or conducting operation on the battery string connected with the turn-off device in series;

when receiving a turn-off command, the turn-off control module stops transmitting a periodic excitation pulse source to the turn-off device to stop supplying power to a processor carried by the turn-off device, and the processor detects the condition of stopping supplying power and executes turn-off operation so as to turn off the photovoltaic module corresponding to the turn-off device; or

When the turn-off control module receives a starting command, the turn-off control module transmits a periodic excitation pulse source to the turn-off device again to restore power supply to a processor carried by the turn-off device, and the processor detects the condition of restoring the power supply and executes conducting operation so as to restore the photovoltaic module corresponding to the turn-off device to a serial connection state from a turn-off state.

The series connection type turn-off system for the photovoltaic module comprises:

the turn-off device comprises a main switch and a first coupling transformer, wherein the main switch and the first coupling transformer are connected with the photovoltaic modules in series through power lines;

a primary winding of the first coupling transformer is connected in series with a main switch provided with a first terminal, a second terminal and a control terminal;

the secondary winding of the first coupling transformer is used for extracting an excitation pulse source loaded on a power line;

the processor detects the potential of the energy storage capacitor, and the main switch is controlled by the processor to be switched off when the processor detects the power supply stopping condition or switched on when the processor detects the power supply recovering condition.

after the turn-off device performs the turn-off operation and turns off the main switch, a parallel capacitor connected in parallel with the main switch provides a conduction path for the excitation pulse source to propagate on the power line.

after the turn-off device executes turn-off operation and closes the main switch, the normally-open parallel switch entering the conducting state provides a conducting path for transmitting an excitation pulse source on the power line; and

when the processor detects the power supply recovery condition and controls to switch on the main switch, the potential of the energy storage capacitor also controls to switch off the normally open parallel switch.

the turn-off device comprises a main switch and an inductor which are connected with the photovoltaic modules in series through power lines;

an inductor in series with a main switch having a first terminal, a second terminal, and a control terminal;

the processor detects the potential of the energy storage capacitor, and the main switch is switched off by the processor when the processor detects the power supply stopping condition or is switched on by the processor when the processor detects the power supply recovering condition;

one end of the inductor is coupled to a first terminal of the main switch and the opposite end of the inductor is connected to an anode of the steering diode, and a cathode of the steering diode is coupled to a preset reference terminal.

By taking the safety level factor of the photovoltaic power generation system into full consideration, taking the sum of the photovoltaic power generation system proposed by the U.S. NEC2017-690.12 standard as an example, the photovoltaic power generation system is required to have the shutdown capability at the component level and provide the best system safety. Through the above explanation of the present application, if the voltage needs to be rapidly reduced to below 30 v, the shutdown control module stops sending the excitation pulse to the shutdown device to notify the shutdown device to shut down the respective corresponding photovoltaic module when receiving an external shutdown command sent by a person, and at this time, the dc bus voltage is approximately equal to zero v, and the system has high safety. Therefore, the component-level turn-off solution has the automatic turn-off capability of the component, and can be used for preventing the irreversible damage of the component and the junction box caused by heat generation caused by fire, hot spots or overlarge wiring resistance of the junction box.

In the present application, the shutdown command may be not only from an external shutdown command issued manually, but also from an internal shutdown command, for example, when the shutdown control module detects a high temperature or an open fire or the like through a sensor, the shutdown command of the shutdown control module may be generated by being triggered by various target faults. In the application, when a starting command is received by the shutdown control module, a stimulation pulse (such as square wave) is transmitted to the shutdown device through the power line so as to charge the energy storage capacitor until the potential of the energy storage capacitor reaches a recovery voltage approved by a processor, so that the shutdown device is triggered to perform the operation of recovering from the shutdown state to the re-serial connection state on the battery string connected in series with the shutdown device, and the voltage can be recovered to be supplied to the bus.

Drawings

To make the above objects, features and advantages more comprehensible, embodiments accompanied with figures are described in detail below, and features and advantages of the present invention will become apparent upon reading the following detailed description and upon reference to the following figures.

Fig. 1 is a schematic diagram of an architecture in which photovoltaic modules are connected in series to form a battery string and a plurality of battery strings are connected in parallel.

Fig. 2 is an architecture for configuring a shutdown device for a photovoltaic module and a shutdown control module for a battery string.

Fig. 3 is a first embodiment of a parallel architecture in which a turn-off control module instructs a turn-off device to turn on or off.

Fig. 4 is a second embodiment of a parallel architecture in which the turn-off control module instructs the turn-off device to turn on or off.

Fig. 5 is a third embodiment of a parallel architecture in which the turn-off control module instructs the turn-off device to turn on or off.

Fig. 6 is a fourth embodiment of a parallel architecture in which the turn-off control module instructs the turn-off device to turn on or off.

Fig. 7 is a fifth embodiment of a parallel architecture in which the turn-off control module instructs the turn-off device to turn on or off.

Fig. 8 is a sixth embodiment of a parallel architecture in which the turn-off control module instructs the turn-off device to turn on or off.

Fig. 9 is a first embodiment of a series architecture in which the turn-off control module instructs the turn-off device to turn on or off.

Fig. 10 is a second embodiment of a series architecture in which the turn-off control module instructs the turn-off device to turn on or off.

Fig. 11 is a third embodiment of a series architecture in which the turn-off control module instructs the turn-off device to turn on or off.

Detailed Description

The technical solutions of the present invention will be clearly and completely described below with reference to various embodiments, but the described embodiments are only used for describing and illustrating the present invention and not for describing all embodiments, and the solutions obtained by those skilled in the art without making creative efforts belong to the protection scope of the present invention.

In the field of photovoltaic power generation, a photovoltaic module or a photovoltaic cell is a core component of power generation. Solar panels are classified into monocrystalline silicon solar cells, polycrystalline silicon solar cells, amorphous silicon solar cells and the like in the mainstream technology, the required service life of the silicon cells is as long as more than twenty years, and monitoring of the durability of the output characteristics of the cells is essential. Many internal and external factors contribute to inefficient power generation of photovoltaic modules: conversion efficiency is reduced due to manufacturing differences or installation differences between the photovoltaic modules themselves or shading or maximum power tracking adaptation. Taking the shielding as an example, if a part of the photovoltaic modules are shielded by clouds, buildings, tree shadows, dirt and the like, the part of the photovoltaic modules can be changed into a load by a power supply and does not generate electric energy any more, the temperature of the photovoltaic modules at a local position with a serious hot spot effect is higher, and some parts of the photovoltaic modules can exceed several hundred degrees centigrade to cause permanent damage such as burning or dark spots, welding spot melting, packaging material aging, glass explosion, corrosion and the like, so that great potential hazards are caused to the long-term safety and reliability of the photovoltaic modules. The photovoltaic power generation system needs to solve the following problems: the working state of each mounted photovoltaic cell panel can be observed in real time or intermittently, the early warning can be carried out on abnormal conditions of over-temperature, over-voltage, over-current, terminal short circuit, various faults and the like of the battery, and the adoption of active safety shutdown or other emergency measures for the abnormal battery is particularly important. The U.S. national electrical code states that the voltage of all photovoltaic power generation systems needs to drop below 30 volts within 10 seconds, and a shutdown device serving as a shutdown function must be configured for the output of the photovoltaic module based on the function of achieving rapid shutdown.

Referring to fig. 1, a photovoltaic module array is the basis for the conversion of light energy to electrical energy in a photovoltaic power generation system. The battery string installed in the photovoltaic module array is shown, with respect to the battery string: each battery string is formed by connecting a plurality of photovoltaic modules which are mutually connected in series, and the photovoltaic modules can be replaced by direct current power supplies such as fuel cells or chemical batteries. A plurality of different battery strings are connected in parallel: although each battery string is composed of a plurality of photovoltaic modules and the plurality of photovoltaic modules inside are connected in series, a plurality of different battery strings are connected in parallel with each other and collectively supply electric energy to an energy collecting device such as a photovoltaic inverter INVT. In a certain battery string, the application takes the series-type multi-stage photovoltaic modules PV1-PVN as an example, and the output voltages V of the series-type multi-stage photovoltaic modules PV1-PVN are respectively_O1-V_ONSuperposed to provide the total string voltage with a higher potential to the inverter INVT, i.e. the bus voltage V_BUSThe inverter INVT carries out inversion from direct current to alternating current after converging the output power of each of the multistage photovoltaic modules connected in series, and N is a natural number larger than 1. A large-capacity capacitor C is connected between the DC buses LA-LB for providing DC power supply for the inverter_DCIn photovoltaic systems, the bus capacitor must also provide decoupling between the constant input power and the fluctuating output power of the inverter.

Referring to fig. 2, each photovoltaic cell or photovoltaic module in an embodiment is configured with a device for performing monitoring and shutdown, that is, a shutdown device for short. In a certain battery string: the electric energy generated by the first-stage photovoltaic module PV1 is determined by the first-stage shutdown device SD1 to be superimposed on the whole battery string, the electric energy generated by the second-stage photovoltaic module PV2 is determined by the second-stage shutdown device SD2 to be superimposed on the whole battery string, and the electric energy generated by the nth-stage photovoltaic module PVN is determined by the nth-stage shutdown device SDN to be superimposed on the whole battery string. The main function of the shut-off device is explained below, for example: the first-stage shutdown device SD1 to the nth-stage shutdown device SDN need to establish communication with another shutdown control module RSD (Rapid Shut-Down), the communication mechanism is compatible with various current communication schemes such as power line carrier communication or various wireless communications, and the shutdown control module RSD at least needs to be equipped with a human-computer interaction function, that is, can receive commands from human beings. If a fire occurs in a power station for various reasons, a fire fighter must first shut down the entire power generation system to fight the fire, otherwise high voltages may jeopardize personal safety. Taking the artificial active operation turn-off control module RSD as an example: when the shutdown control module RSD receives a shutdown command, for example, an emergency shutdown switch provided by the shutdown control module RSD is pressed to indicate that a shutdown command is reached, at this time, the shutdown control module RSD immediately sends a first command, that is, a shutdown command, to the multi-stage shutdown device SD1-SDN based on communication, and may be represented by a logic level signal, so as to notify the multi-stage shutdown device SD1-SDN to shut down the corresponding photovoltaic module PV1-PVN, so that the voltage output by the battery string connected between the dc buses LA-LB immediately drops to approximately zero as desired.

Referring to fig. 2, the present application, in an optional but not necessary embodiment, assumes that the interior of the string of cells is connected in series with a first stage photovoltaic module PV1, a second stage photovoltaic module PV2, and so on, to an nth stage photovoltaic module PVN. It can be known that the total string-level voltage that can be provided on an individual certain battery string is approximately equal to: the voltage value V output by the first-stage photovoltaic module PV1_O1Plus the voltage V output by the photovoltaic module PV2 of the second stage_O2Then, the voltage V output by the photovoltaic module PV3 of the third stage needs to be added_O3…, and so on, adding up to the voltage value V output by the photovoltaic module PVN of the Nth stage_ONThe total cascade voltage is calculated to be equal to V_O1+V_O2+…V_ON. The cascade voltage obtained by superposing the voltages output by the multi-stage photovoltaic modules on the bus LA-LB is transmitted to electric equipment such as a combiner box or an inverter for combination and inversion, and then is connected to the grid or used locally. The photovoltaic modules PV1-PVN correspond to the shutdown devices SD1-SDN, and the specific scheme of superposing cascade voltage is that the first-stage shutdown devices SD1, the second-stage shutdown devices SD2, … and the like are connected in series through power lines until the Nth-stage shutdown devices SDN and the like. Basic definition regarding the shut-off device: the shutdown device is used to shut down the corresponding photovoltaic module for removal from the string of battery packs, or in the present application, the shutdown device is used to restore the corresponding photovoltaic module from a shutdown state to a series connection state into the string of battery packs.

Referring to fig. 2, it is mentioned that when the shutdown control module RSD sends a so-called shutdown command to the shutdown devices SD1-SDN, the shutdown devices SD1-SDN are notified to shut down the corresponding photovoltaic modules PV1-PVN to ensure system safety, the voltage between the dc buses LA-LB may be pulled down to be nearly equal to zero as desired to ensure safety, and the shutdown control module RSD is ready to receive a startup command at any time. The start command may be generated at any time, for example, when a fire alarm occurs to cut off the entire battery string, and after the fire alarm is released, the system needs to be restarted to enable the photovoltaic power generation system to enter the working state again to supply voltage to the bus.

Referring to fig. 2, the control mode for restarting the system again after it is turned off is: the shutdown control module RSD, upon receiving a startup command, sends a startup instruction to the plurality of shutdown devices SD1-SDN opposite to the aforementioned shutdown instruction to inform the shutdown devices to restore the respective corresponding photovoltaic modules PV1-PVN from the shutdown state to the series-connected state. As is known, the shutdown control module RSD at least needs to be equipped with a human-computer interaction function, the start command may be a command issued manually, and pressing a start switch equipped in the shutdown control module RSD can represent that a start command is reached, and the shutdown control module needs to immediately issue a second command, i.e., a start command, to the shutdown device SD1-SDN, where the second command may be represented by a logic level signal. The data or instruction communication between the shutdown control module and the shutdown device can be power line carrier or wireless communication, and even the excitation pulse provided by the application is used as a communication means. The shutdown devices SD1-SDN receive a startup command and then restore their respective corresponding photovoltaic modules from a shutdown state to a series-connected state, and the voltage output by the battery string between the dc buses LA-LB immediately restores to provide a cascade voltage to the buses as desired, where the voltage level of the cascade voltage is very high and can be typically as high as several hundred volts or even thousands of volts. Compared with the embodiment of fig. 1 without any shutdown measures, the embodiment of fig. 2 has a fast shutdown function and meets the safety specification, and meets the user requirement of component-level high-reliability shutdown.

With reference to fig. 3, it is observed in the whole link of the multi-stage shutdown device SD1-SDN series connection: the second output of any preceding stage of turn-off device is coupled to the first output of an adjacent succeeding stage of turn-off device, thereby satisfying: the maximum total string-level voltage that can be provided in a battery string is equal to the final sum of the output voltages of the respective multi-level shutdown devices SD 1-SDN. The specific relationship is as follows: the second output O2 of the first stage shutdown device SD1 is coupled to the first output O1 of the adjacent succeeding stage, i.e. the second stage shutdown device SD2, the second output O2 of the second stage shutdown device SD2 is coupled to the first output O1 of the adjacent succeeding stage, i.e. the third stage shutdown device SD3, until the second output NO2 of the N-1 stage shutdown device is coupled to the first output O1 of its succeeding stage shutdown device SDN. The voltage output by each of the multi-stage turn-off devices is equivalent to the cascade voltage obtained by superposing the multi-stage photovoltaic modules and is transmitted to the energy collecting device. We can also observe that the first output O1 of the first stage shutdown device SD1 is coupled to the bus bar LA, and can also observe that the second output O2 of the last nth stage shutdown device SDN is coupled to the bus bar LB.

Referring to fig. 3, the shutdown device is used to shut down the photovoltaic module corresponding thereto for removal from the string of battery packs or to restore the photovoltaic module corresponding thereto from the shutdown state to the series-connected state of the connected string of battery packs. The first input of any one of the turn-off devices is coupled to the positive pole of the corresponding photovoltaic module and the second input of the turn-off device is coupled to the negative pole of the corresponding photovoltaic module. Such as: a first input N1 of the shutdown device SD1 is coupled to the positive pole of the photovoltaic module PV1 and a second input N2 of the shutdown device SD1 is coupled to the negative pole of the photovoltaic module PV 1. In another more representative example: a first input N1 of the shutdown device SDN is coupled to the positive pole of the respective photovoltaic module PVN and a second input N2 of said shutdown device SDN is coupled to the negative pole of the photovoltaic module PVN. In the field, any one of the turn-off devices includes a switching element disposed between the first input terminal N1 and the first output terminal O1, and may further include a switching element disposed between the second input terminal N2 and the second output terminal O2, so that if the turn-off device needs to turn off the corresponding photovoltaic module and remove the corresponding photovoltaic module from the battery string, the switching element is controlled to be turned off, and conversely, if the turn-off device needs to restore the corresponding photovoltaic module from the off state to the series connection state of the connected battery string, the switching element is controlled to be turned on. Naturally, in the field of photovoltaic power generation, there are several alternative variants of the shut-off device for so-called photovoltaic modules, but the basic functions are: the photovoltaic module is switched off or on. A bypass switch diode provided in the turn-off device is additionally coupled between the first output NO1 and the second output NO 2. It is noted that the bypass diode is arranged with its anode connected to the second output NO2 and with its cathode connected to the first output NO1, so that the bypass diode is turned off in the reverse direction when the photovoltaic module is controlled by the corresponding turn-off device to return to the series-connected state, and so that the bypass diode is turned on in the forward direction when the photovoltaic module is switched to the turned-off state by the corresponding turn-off device.

Referring to fig. 3, the operating mechanism of the shut-off device can be generally described as: if the switching element between the input and the output is on, this means that the turn-off device will turn on the corresponding photovoltaic module, which corresponds to the photovoltaic module being connected to the string of batteries and contributing its voltage component to the string voltage, and the bypass diode is then turned off in the opposite direction. Correspondingly, if the switching element between the input terminal and the output terminal is turned off, it means that the turn-off device performs a turn-off operation on the corresponding photovoltaic module, so that the photovoltaic module can no longer contribute its voltage component to the string voltage, that is, the bypass diode is turned on in the forward direction when the photovoltaic module is removed from the battery string, and the practical meaning is that: and a bypass diode provides a conduction path between two output ends of the turn-off device corresponding to the turned-off photovoltaic module.

Referring to fig. 3, a parallel shutdown system implies, as the name implies, that the shutdown device and the corresponding photovoltaic module are connected in parallel. The shutdown devices SD1-SDN and the photovoltaic modules PV1-PVN are connected in parallel in a one-to-one manner, so that one shutdown device is provided for each photovoltaic module. Whether the shutdown device SD1-SDN performs shutdown operation or whether the SDN performs turn-on operation is controlled by the shutdown control module RSD, and the shutdown control module RSD is artificially controlled or controlled by a preset condition, for example, occurrence or release of high temperature, high voltage, overcurrent, open flame or extreme cold weather can trigger the shutdown control module RSD to issue a shutdown or turn-on command, and the multiple photovoltaic modules are connected in series to form a battery string. The shutdown device is used for shutting down the photovoltaic component corresponding to the shutdown device to remove the photovoltaic component from the battery string or restoring the photovoltaic component corresponding to the shutdown device from the shutdown state to the series connection state of the connection battery string. Typical shutdown devices SDN for example are used to shut down the corresponding photovoltaic module PVN from the string or to restore the corresponding photovoltaic module PVN from a shutdown state to a series access state into the string. When the turn-off control module RSD receives the turn-off command, for example, the emergency turn-off switch/voice-operated switch/turn-off button/touch screen turn-off switch provided in the turn-off control module is activated to issue the turn-off command, and the turn-off control module has a man-machine interaction function. The shutdown control module RSD adopts the following scheme for the mode of commanding a so-called shutdown to the exemplary shutdown device SDN: the shutdown control module RSD is configured to send the excitation pulse source PUS to the shutdown device SDN uninterruptedly or at least intermittently or periodically when controlling the shutdown device SDN to be in a normal on state to ensure that the battery assembly PVN is able to contribute its own voltage component to the cascade voltage, and the photovoltaic assembly PVN is now able to contribute its own voltage component to the bus since the shutdown device SDN is turned on and is directly connected in series between the buses LA-LB. In contrast, if the shutdown control module RSD attempts to control the shutdown device SDN to be in the shutdown state such that the battery assembly PVN is removed from between the dc buses LA-LB, it is necessary to stop sending the so-called excitation pulse source PUS to the shutdown device SDN, and it is needless to say that the photovoltaic assembly PVN cannot contribute any more voltage component to the buses because the shutdown device SDN is in the shutdown state and is directly removed from between the dc buses LA-LB. Generally, the mode in which the shutdown control module instructs the shutdown device SDN to shutdown is considered as follows: if the supply of periodic excitation pulse sources PUS to the shutdown device SDN is stopped, this may indicate that the shutdown device SDN needs to perform a shutdown operation on the battery assembly PVN. It is noted that, although the shutdown device SDN is taken as an example, the electrical characteristics of the other shutdown devices SD1-SD (N-1) remaining in the shutdown device SD1-SDN are not substantially different from the shutdown device SDN.

Referring to fig. 3, the turn-off device SDN comprises a main switch M and a first coupling transformer T₁And further comprises two inputs N1-N2 connected to the positive and negative poles of the photovoltaic module PVN, respectively, and the turn-off device SDN further comprises two outputs O1-O2 connected in series with the remaining other turn-off devices, the two outputs of the turn-off device SDN when turned on providing the output power and the output voltage of the photovoltaic module PVN. A bypass diode DP is further arranged between the two outputs O1-O2 of the shutdown device SDN, and when the photovoltaic module PVN is shutdown by the shutdown device SDN, the bypass diode DP provides a conduction path between the two outputs O1-O2 of the shutdown device SDN corresponding to the shutdown photovoltaic module PVN. Assuming that the main switch M of the turn-off device SDN has a first terminal and a second terminal and a control terminal, the first terminal being connected to the second output O2 of the turn-off device and the second terminal being connected to the second input N2, the main switch is selectively connected between the second input and the second output is the embodiment adopted in fig. 3. In the alternative, the first terminal of the main switch M may also be connected to the first output O1 of the turn-off device and the second terminal to the first input N1, i.e. in the alternative the main switch MThe switch is selectively connected between the first input terminal and the first output terminal. The main switch is used for switching between the input terminal and the output terminal, for example, the first input terminal N1 and the first output terminal O1 can be controlled to be switched between the input terminal and the output terminal, and for example, the second input terminal N2 and the second output terminal O2 can be controlled to be switched between the input terminal and the output terminal: when the main switch is switched off, the corresponding photovoltaic module is removed from the battery pack string, and when the main switch is switched on, the corresponding photovoltaic module is restored to be connected into the battery pack string.

Referring to fig. 3, the turn-off device SDN in this embodiment comprises said first coupling transformer T coupled to the second output O2 by a power line₁The specific connection relationship is as follows: first coupling transformer T₁The primary winding L1 and the first terminal of the main switch are connected to one of two output terminals O1-O2, namely to the second output terminal O2. In detail, the primary winding L1 is connected between the second output O2 of the shut-off device SDN and the bus bar LB. In the alternative embodiment of fig. 3, the second terminal of the main switch M is directly connected to the second input N2 and the so-called first input N1 and first output O1 in the topology of the turn-off device SDN are directly coupled together.

Referring to fig. 3, a modification is made based on fig. 3 but in an alternative not shown: the shutdown device SDN comprises a first coupling transformer T coupled to, for example, a first output O1 via a power line₁In this embodiment, which is not shown, it corresponds to the first coupling transformer T which we will describe₁The primary winding L1 of the primary winding is directly moved between the second output O2 of the adjacent previous-stage shutdown device SD (N-1) and the first output O1 of the next-stage shutdown device SDN. This solution also modifies the position of the main switch M: the main switch is moved from between the second output O2 and the second input N2 previously connected to the turn-off device to between the first output O1 and the first input N1 connected to the turn-off device, setting a first terminal of the main switch to the first output O1 of the turn-off device and a second terminal to the first input N1. In the alternative, the transformer T is connected by the first coupling₁The primary winding is moved between the second output O2 of the shut-off device SD (N-1) and the first output O1 of the shut-off device SDNIn the examples: first coupling transformer T₁The primary winding and the first terminal of the main switch are connected to the other of the two output terminals O1-O2, i.e. the first output terminal O1. In contrast to the example of fig. 3, this alternative embodiment assumes that the primary winding L1 is connected between a first output of the shutdown device SDN and a second output of the shutdown device SD (N-1). Thus in an alternative embodiment to fig. 3: we can provide that the second terminal of the main switch is directly connected to the first input N1, and that in the turn-off device SDN so-called second input N2 and second output O2 are directly coupled together. An alternative to making the correction based on fig. 3 is to prove that there are two options: the main switch is selectively connected between the second input end and the second output end, so that the primary winding of the first coupling transformer and the first terminal of the main switch are connected to the second output end of the two output ends, namely, fig. 3; the main switch is selectively connected between the first input terminal and the first output terminal, and the primary winding of the first coupling transformer and the first terminal of the main switch are connected to the first of the two output terminals, the latter being based on the modification of fig. 3.

Referring to fig. 3, it can be seen that the main switch M is selectively connected between the second input terminal and the second output terminal in the embodiment of fig. 3 explained above. In an alternative, the first terminal of the main switch M may also be connected to the first output O1 of the turn-off device and the second terminal to the first input N1, i.e. in the alternative to fig. 3 the main switch is selectively connected between the first input and the first output. In summary: the main switch is used to switch the input terminal and the output terminal, such as to switch the first input terminal N1 and the first output terminal O1, and to switch the second input terminal N2 and the second output terminal O2. When the main switch is switched off, the corresponding photovoltaic module is removed from the battery pack string, and when the main switch is switched on, the corresponding photovoltaic module is restored to be connected into the battery pack string.

Referring to fig. 3, a first coupling transformer T₁The secondary winding L2 is used to sense or extract the excitation pulse source PUS loaded on the power line, and the sensed excitation pulse source PUS is passed through a steering diode D2, the energy storage capacitor C1 connected between the predetermined reference terminal NRF and the first terminal is charged, the processor 80 detects the power restoration condition of the energy storage capacitor C1 and performs the on operation, and the main switch M is controlled by the processor 80 to be turned on, otherwise, the main switch M is turned off. This applies to the embodiment of fig. 3 as well as to the alternative embodiment not shown in fig. 3, in which one end of the secondary winding L2 of the so-called first coupling transformer, e.g. the synonym and the first terminal of the main switch, are coupled to said second output O2, in fig. 3 the alternative embodiment not shown in fig. 3, one end of the secondary winding L2 of the first coupling transformer, e.g. the synonym and the first terminal of the main switch, are coupled to the first output O1, which differs mainly from the position of the main switch described above, in fig. 3 the main switch is arranged between the second input N2 and the second output O2, while in the alternative embodiment the main switch is shifted to be arranged between the first input N1 and the first output O1, but functions of both are the same. The power line or series line referred to herein may actually be considered as an extension of the bus bar. The main switch may be a metal oxide semiconductor field effect transistor MOSFET or an insulated gate bipolar transistor IGBT or the like. The main switch is a three-port electronic switch, the mosfet includes a gate, a source and a drain, and the igbt includes a gate, a collector and an emitter. A field effect transistor has a second terminal, such as a drain D, and has a first terminal, such as a source S, and a control terminal, such as a gate G, and an insulated gate bipolar transistor has a second terminal, such as a collector C, and has a first terminal, such as an emitter E, and a control terminal, such as a gate G. A general field effect transistor is characterized in that it is turned on when a voltage value up to a turn-on threshold voltage is applied between a gate and a source, and a general insulated gate bipolar transistor is characterized in that it is turned on when a voltage value up to a turn-on threshold voltage is applied between a gate and an emitter. The power semiconductor switch device has: metal oxide semiconductor field effect transistors, bipolar transistors, thyristors, gate turn-off thyristors, integrated gate commutated thyristors, turn-off thyristors, and emitter turn-off thyristors, insulated gate bipolar transistors.

Referring to fig. 3, a first coupling transformer T₁Is connected to a second output O2, and is connected to a primary winding L1 and a main switch M having first and second terminals and a control terminal. The signal at the control terminal of the main switch M, i.e. the drive signal output by the processor 80, determines whether the first and second terminals of the main switch are on or off, and the coupling transformer may be replaced by a transformer. The first coupling transformer, because of its coupling effect, has its secondary winding L2 used to extract or inductively switch off the excitation pulse source PUS that the control module RSD loads onto the power line, which may be pulsed voltage and is most common and most frequently used with square wave pulses. In order to satisfy the requirement that the secondary winding L2 can induce and capture the excitation pulse source PUS, a first coupling transformer T is provided₁The synonym terminal of the secondary winding L2 is coupled to the first terminal of the main switch M, i.e. to the common node NCO and the common node NCO is considered to have the reference ground potential GR. The dotted terminal of the first coupling transformer secondary winding L2 is provided to be coupled to a predetermined reference terminal NRF through a steering diode D2. Specific first coupling transformer T₁The dotted terminal of the secondary winding L2 is coupled to a first node N1 through a first capacitor CC, the steering diode is connected between the first node N1 and a predetermined reference terminal NRF, and the anode terminal of the steering diode D2 is connected to the first node N1 and the cathode terminal is connected to the predetermined reference terminal NRF.

Referring to fig. 3, in addition to this, we also have a first coupling transformer T₁Between the synonym terminal of the secondary winding L2 and said first node N1 mentioned above is additionally connected a separate first diode D1, note that the anode of the first diode D1, which has the reference ground GR, is connected to the first coupling transformer T₁The synonym terminal of the secondary winding L2, and the cathode of a first diode D1 is provided to be connected to the first node N1. The excitation pulse source PUS captured or induced by the secondary winding L2 from the power line charges the energy storage capacitor C1 connected between the predetermined reference terminal NRF and the first terminal, i.e. the energy storage capacitor C1 arranged between the gate G and the common node NCO by the excitation signal, via the steering diode D2, which allows unidirectional charging of the induced pulseCharging the energy storage capacitor. In an alternative embodiment, a parallel resistor R1 is also provided between the predetermined reference terminal NRF and the first terminal/common node NCO, in parallel with the energy storage capacitor. The sensed excitation pulse source PUS charges the energy storage capacitor C1, the main switch M is turned on when the potential of the energy storage capacitor C1 reaches the power restoration condition detected by the processor 80, otherwise, the main switch M is turned off when the potential of the energy storage capacitor C1 does not reach the power restoration condition detected by the processor 80. According to the semiconductor physics theory, the equivalent physical model of the solar module comprises a diode factor, an equivalent series resistance, an equivalent parallel resistance and the like, and the output impedance characteristics of the photovoltaic module are greatly different under the influence of different illumination intensities and different temperature environments. The transmission path of the excitation pulse is transmitted through the internal resistance of each photovoltaic module, and the degradation degree of the excitation pulse on the transmission path of the multi-stage photovoltaic module is hardly predictable under the condition that the impedance of the photovoltaic module is greatly deviated along with the external environment. In the fuzzy signal processing, the combination of the first capacitor CC and the first diode D1 is used to raise the potential of the excitation pulse source PUS by a certain amplitude in at least some embodiments to avoid excessive attenuation.

Referring to fig. 4, the first terminal of the main switch M and the first coupling transformer T in the turn-off device SDN₁The so-called primary winding L1 is connected to the second output O2, the first capacitor CC and the first diode D1 being omitted with respect to fig. 3. Providing a first coupling transformer T in a so-called shut-down device SDN₁The first terminal of the primary winding L1 and the main switch M are connected to the second output O2 and the second terminal of the main switch M is connected to the second input N2. Wherein it is noted that the first coupling transformer T₁The secondary winding L2 is used to extract the excitation pulse source PUS loaded on the power line, and as a coupling function of the signal, the excitation pulse source PUS signal induced or captured by the secondary winding L2 charges the energy storage capacitor C1 connected between the predetermined reference terminal NRF and the first terminal, e.g., the source electrode S, via the steering diode D2. The common node NCO and the first terminal are coupled together. At a preset reference terminal NRF and the common node NCO/first terminalA parallel resistor R1 connected with the energy storage capacitor C1 in parallel is further arranged between the two resistors. In an alternative embodiment, the steering diode D2 has its anode terminal directly connected to the same name terminal of the secondary winding L2 and its cathode terminal connected to the predetermined reference terminal NRF. A pair of anti-series connected zener diodes Z1-Z2 connected in parallel with the energy storage capacitor C1 are also provided between the preset reference terminal NRF and the first terminal or common node in an alternative embodiment. The reverse series connection of the zener diodes Z1-Z2 refers to: the anodes of the zener diodes Z1 and Z2 are interconnected, the cathode of the zener diode Z1 is connected to the first terminal or common node NCO, and the cathode of the zener diode Z2 is connected to the predetermined reference terminal NRF such that the pair of series-connected zener diodes is connected in parallel with the energy storage capacitor C1, it being noted that this embodiment may also be applied to the embodiment of fig. 3 as well. The back-to-back reverse series connected voltage stabilizing diodes are used for clamping the voltage drop between the control terminal and the first terminal of the main switch, and the power switch is prevented from being damaged.

Referring to fig. 5, there are several ways for the shutdown control module RSD to supply periodic excitation pulse sources PUS to the shutdown device SDN or to the power line. In this embodiment: the excitation pulse source PUS is generated in the form of a high-low logic level by a pulse signal generator, which may be an ac signal, provided with the shutdown control module RSD. Second coupling transformer T in this embodiment₂There is also a primary winding and a secondary winding, and the primary winding is connected in series to the power line, and the primary winding and the series of cut-off devices SN1-SDN are connected in series by the power line. A second coupling transformer T is also provided₂Is connected in series between a further reference ground GG, denoted second reference ground potential, to be distinguished from the above-mentioned reference ground potential GR, denoted first reference ground potential, to avoid confusion, and the potentials of both may be different, and the coupling capacitor OC. The working mechanism of the turn-off control module RSD is as follows: outputting the generated excitation pulse source PUS via a driver DR, and finally passing the excitation pulse source PUS through a second coupling transformer T₂Is propagated or applied to the power line by coupling of the primary winding and the secondary winding, here called excitation pulsesThe source PUS is a square wave or similar other pulsating signal. Any scheme in the art for loading or propagating a periodic or intermittent pulsed signal onto a power line may be substituted for the embodiment of fig. 5.

Referring to fig. 6, when the shutdown control module RSD tries to control the shutdown device SDN to be in the normal on state, the excitation pulse source PUS must be continuously or intermittently sent, and the shutdown device SDN senses the excitation pulse source PUS and charges its own energy storage capacitor to maintain the shutdown device SD on, that is, the condition that the potential of the energy storage capacitor C1 reaches the condition that the processor 80 detects the power restoration condition is satisfied. If the shutdown control module RSD no longer expects the shutdown device to be in a normal on state but to be shutdown, the emergency shutdown control module RSD may stop the excitation pulse source PUS that is originally sent to the shutdown device SDN uninterruptedly, intermittently, or periodically when receiving the shutdown command, in which case the energy storage capacitor C1 may be powered down and the processor 80 may detect the power supply stop condition because of monitoring the power condition of the energy storage capacitor C1. The mode of the turn-off control module RSD giving the turn-off instruction to the turn-off device is as follows: the supply of the periodic excitation pulse source to the shutdown device is stopped, and the processor 80 provided in each shutdown device may be stopped to supply power to the processor 80 provided in each shutdown device, since the supply of the periodic excitation pulse source PUS to each shutdown device SD1-SDN is actively stopped, and the processor 80 detects the power supply stop and performs the shutdown operation, so as to shut down the photovoltaic module corresponding to each shutdown device, for example, the shutdown device SDN may be notified to perform the shutdown operation on the photovoltaic module PVN corresponding to the shutdown device SDN.

Referring to fig. 6, the method of restarting the system again if an attempt is made without hindrance after the shutdown device SDN is shut down under the instruction of shutdown needs to be separately designed. Before the shutdown control module RSD waiting for the start command receives the start command, the shutdown control module RSD controls the shutdown device SDN to enter the shutdown mode, and the photovoltaic module corresponding to the shutdown device entering the shutdown mode cannot be connected between the dc buses to supply power to the dc buses. The main switch is disconnected, although the bus can be disconnected to ensure safety, the bus also has the negative defect that the excitation emitted by the switching-off control module RSDThe excitation pulse source PUS can no longer propagate smoothly in a closed loop, which is a loop formed by the main switch and the bus bars LA-LB formed by a series of series-connected cell assemblies PV 1-PVN. The unique design of the system restart method is as follows: the shutdown device SDN is configured to perform an operation of recovering from the shutdown state to the re-series connection state on the battery string connected in series therewith, that is, when the shutdown control module RSD receives a start command, for example, a physical start switch/touch screen switch/voice-operated switch provided for triggering the shutdown control module is characterized to have reached the start command, the shutdown device SDN is sent a periodic excitation pulse source PUS through the power line again to notify the shutdown device SDN to perform an operation of re-connecting the corresponding photovoltaic module, and at this stage, the shutdown control module RSD immediately sends a start instruction again to the shutdown device. It has been discussed above that the failure of the periodic excitation pulse source PUS, which is delivered again to the shut-down device via the power line due to the opening of the main switch M, to form a closed propagation path via the opened main switch M, in other words, the failure of the secondary winding to sense a pulse, directly causes difficulties in the operation of the shut-down device SDN to perform a re-series connection. The method for solving the problem that the excitation pulse source PUS is transmitted in the closed loop comprises the following steps: the turn-off device SDN is provided with a parallel capacitor CP connected between a first terminal, such as a source, and a second terminal, such as a drain, of the main switch M, and the parallel capacitor CP connected in parallel with the main switch M provides a conduction path for the excitation pulse source PUS to propagate on the power line after the turn-off device SDN performs a turn-off operation and turns off the main switch M. After the shutdown control module RSD receives the starting command, the shutdown control module instructs a shutdown device SDN to recover the corresponding photovoltaic modules PVN from the shutdown state of the system shutdown stage to the series connection state through an excitation pulse source PUS, the power generation system containing the photovoltaic modules PV1-PVN of the battery string is rapidly restarted, and the voltage of the DC bus LA-LB is rapidly increased to be equal to V_O1+V_O2+…V_ON. The whole idea is that the parallel capacitor CP ensures that the excitation pulse source PUS can be transmitted when the main switch M is turned off, the main switch M is turned on again by charging the energy storage capacitor with the excitation pulse source PUS, and the potential of the energy storage capacitor reaches the processor80 are able to detect a power restoration condition, the shut-down device is able to perform a series re-connection operation on the battery string connected in series therewith. When receiving a starting command, the shutdown control module transmits periodic excitation pulse sources to the shutdown devices SD1-SDN again to restore power supply to the processors 80 of the shutdown devices SD1-SDN, the processors 80 monitor the charging capacity of the energy storage capacitor to detect and restore the power supply condition, the processors execute conducting operation when detecting and restoring the power supply, and the corresponding photovoltaic modules PVNs of the shutdown devices SDN and the like are restored to the series connection state from the shutdown state.

Referring to fig. 7, the aforementioned confusion of attempting to restart the system after the shutdown device SDN is shutdown under the instruction of shutdown lies in: the excitation pulse source PUS emitted by the turn-off control module RSD can no longer propagate smoothly in the closed loop and is mainly caused by the main switch being opened. As an alternative to the embodiment of fig. 6, an alternative approach to addressing the propagation of the excitation pulse source in the closed loop is: the turn-off device SDN is configured with a normally open parallel switch MP connected between a first terminal and a second terminal of the main switch M. Normally-open (Normally-ON) parallel switch MP defaults to being in an ON state if it is not actively controlling its ON or off state under normal conditions. The types of devices that can be used for the normally-on parallel switch MP are, for example, a junction field effect transistor JFET, the drains and sources of which are respectively considered as first and second terminals and which can be interchanged. The control terminal G of the normally-open parallel switch MP is connected to a preset reference terminal NRF, and the first and second terminals of the normally-open parallel switch MP are correspondingly connected to the first and second terminals of the main switch, respectively. After the turn-off device SDN performs the turn-off operation and turns off the main switch M, the normally-open parallel switch enters a default on state. Conversely, if the energy storage capacitor is charged to cause a potential difference between the first terminal or the second terminal of the normally-open parallel switch and the gate control terminal, the normally-open parallel switch enters a cut-off state. After the turn-off device performs the turn-off operation and closes the main switch M, the normally-open parallel switch MP entering the on-state provides the on-path for the excitation pulse source PUS to propagate on the power line in the present application. When the turn-off control module RSD controls the turn-off device to be in a normal on state, for example, when it is ensured that the turn-off device SDN and the battery string are connected in series, it is necessary to send a driving pulse source PUS to the turn-off device SDN uninterruptedly or at least intermittently or periodically, and when the main switch M is turned on because the charging of the pulse signal makes the potential of the energy storage capacitor C1 reach the recovery power supply voltage authorized by the processor 80, in order to avoid interference between the main switch and the normally-open parallel switch, the charged potential of the energy storage capacitor C1 is also used as a pinch-off voltage to control the normally-open parallel switch MP in the type of junction field effect transistor to be turned off. The overall idea is that the normally-open parallel switch ensures that the excitation pulse source PUS can be transmitted when the main switch M is turned off, the main switch is enabled to be turned on again by charging the energy storage capacitor through the excitation pulse source PUS, and the condition that the potential of the energy storage capacitor reaches the turn-on threshold voltage of the main switch is met, so that the turn-off device can execute the operation of series connection again on the battery string connected with the turn-off device in series. It should be noted that in some optional but non-necessary embodiments, the turn-off instruction causes the energy storage capacitor to gradually power down, and the main switch M is turned off in advance during the power down process of the energy storage capacitor because the potential cannot reach the recovery power supply voltage authorized by the processor 80, and at this time, the normally-open parallel switch MP is clamped in the turn-off region because the charge of the energy storage capacitor is not yet zero, until the power down of the energy storage capacitor is ended, the gate-source voltage of the normally-open parallel switch MP cannot be affected any more, so that the parallel switch enters the default on state.

With reference to fig. 8, by modifying the parallel shutdown system for photovoltaic modules mentioned above, in particular in the embodiments of fig. 2-7, it comprises: the system comprises a shutdown control module RSD, a plurality of shutdown devices SD1-SDN and a plurality of series-connected photovoltaic modules PV1-PVN, wherein each photovoltaic module is provided with one shutdown device, and the photovoltaic modules are connected in series to form a battery string. The shutdown device is used for shutting down the photovoltaic component corresponding to the shutdown device and removing the photovoltaic component from the battery string, or the shutdown device is used for restoring the photovoltaic component corresponding to the shutdown device from a shutdown state to a serial connection state of the connected battery string. In an alternative embodiment, the shutdown control module RSD stops delivering the periodic excitation pulse source PUS to each shutdown device SD1-SDN upon receiving the shutdown command to notify the plurality of shutdown devices SD1-SDN to perform the shutdown operation to shut down the corresponding photovoltaic modules PV 1-PVN. Or when the shutdown control module RSD receives the start-up command, it will continue to deliver again the periodic excitation pulse source PUS to each shutdown device SD1-SDN to inform the plurality of shutdown devices to perform the turn-on operation to restore the respective corresponding photovoltaic module PV1-PVN from the off-state to the series-connected state.

With reference to fig. 8, by modifying the parallel shutdown system for photovoltaic modules mentioned above, in particular in the embodiments of fig. 2-7, each shutdown device, such as an SDN, comprises a main switch M for switching off or on between its input and output, the main switch M having a first terminal, a second terminal and a control terminal. The main switch M may be used to switch off or on between its first input N1 and first output O1 if it is connected between the first input N1 and first output O1, and between its second input and second output if it is connected between the second input N2 and second output O2. The shutdown device SDN comprises an inductor LS coupled to its output, such as the second output O2 or the first output O1, by a power line. Coupling element T₃The above first coupling transformer can be replaced and the coupling element mainly comprises an inductor LS. One end of the inductor LS is connected to the first terminal of the main switch M at the second output terminal O2 of the two output terminals, or one end of the inductor LS is connected to the first terminal of the main switch M at the first output terminal O1 of the two output terminals. The other end of the inductor LS is connected to an anode of a steering diode D2 and a cathode of the steering diode D2 is coupled to the predetermined reference terminal NRF. The inductor LS is used to extract the excitation pulse source PUS loaded on the power line, and the induced excitation pulse source PUS charges the energy storage capacitor C1 connected between the preset reference terminal NRF and the first terminal via the steering diode D2. The processor 80 detects the potential condition of the energy storage capacitor, the processor 80 detects the condition of stopping power supply, namely the capacitor is powered off, the main switch M is controlled by the processor to be switched off, or the processor 80 detects the condition of recovering power supply, namely the capacitor is charged, then the main switch is controlled by the processor to be connectedThe method is simple.

With reference to fig. 8, by modifying the parallel shutdown system for photovoltaic modules mentioned above, in particular in the embodiments of fig. 2-7: the turn-off device SDN comprises two input ends N1-N2 connected to the positive and negative electrodes of the photovoltaic module respectively and two output ends O1-O2 connected with other turn-off devices in series, a bypass diode DP is arranged between the two output ends O1-O2 of the turn-off device SDN, and when the photovoltaic module PVN is turned off, a conduction path between the two output ends O1-O2 of the turn-off device SDN corresponding to the turned-off photovoltaic module is provided by the bypass diode DP. In an alternative embodiment, a parallel resistor R1 connected in parallel with the energy storage capacitor C1 is further provided between the control terminal and the first terminal of the main switch. In an alternative embodiment an anti-series connected zener diode Z1-Z2 connected in parallel with the energy storage capacitor C1 is also provided between the control terminal and the first terminal of the main switch. In an alternative embodiment, the turn-off device SDN comprises a parallel capacitor CP connected between the first terminal and the second terminal of the main switch, as may be seen in fig. 6 and 8, and after the turn-off operation is performed by the turn-off device SDN and the main switch is closed, a conduction path is provided by the parallel capacitor CP connected in parallel with the main switch M for the excitation pulse source to propagate around the main switch. In an alternative embodiment, the turn-off device SDN further includes a normally-open parallel switch MP connected between the first terminal and the second terminal of the main switch, as shown in fig. 7 and 8, a control terminal of the normally-open parallel switch MP is connected to a preset reference terminal NRF, and after the turn-off device M performs the turn-off operation, the normally-open parallel switch MP entering the on state provides a conduction path through which the excitation pulse source PUS propagates by bypassing the main switch; and when the potential of the energy storage capacitor reaches the power restoration condition detected by the processor 80 and the main switch is turned on, the potential of the energy storage capacitor C1 also controls the normally open parallel switch MP to be turned off. Note that all of the features possessed by and described in relation to the various embodiments of fig. 2-7 may also be applied to the embodiment set forth in fig. 8. Coupling element T₃Instead of the first coupling transformer described above, the inductor LS replaces the primary winding of the first coupling transformer. The inductor LS may be arranged between the second output terminal of the previous-stage turn-off device and the second output terminal of the adjacent subsequent-stage turn-off deviceAn inductor LS may be arranged between the first output of the first-stage turn-off device and the bus bar LA, or even between the second output of the last-stage turn-off device and the bus bar LB.

Referring to fig. 9, in the entire string of batteries with multi-level photovoltaic modules PV1-PVN connected in series, it is observed that: the negative terminal of any previous-stage photovoltaic assembly is coupled to the positive terminal of the adjacent next-stage photovoltaic assembly, so that the following conditions are met: the maximum total string voltage provided by a certain battery string is equal to the final superposition value of the output voltages of the photovoltaic modules PV1-PVN in the plurality of battery strings. The specific relationship is as follows: the negative electrode output end Q2 of the first-stage photovoltaic assembly PV1 is coupled to the positive electrode output end Q1 of the adjacent later-stage photovoltaic assembly PV2, the negative electrode output end Q2 of the second-stage photovoltaic assembly PV2 is coupled to the positive electrode output end Q1 of the adjacent later-stage photovoltaic assembly PV3, and the negative electrode output end Q2 of the photovoltaic assembly of the Nth-1 stage is coupled to the positive electrode output end Q1 of the photovoltaic assembly PVN of the later-stage. Therefore, cascade voltage obtained by superposing the voltages output by the photovoltaic modules is transmitted to the energy collecting device. It is also observed that the positive output Q1 of the first stage photovoltaic module is coupled to the bus bar LA, and that the negative output Q2 of the last nth stage photovoltaic module is coupled to the bus bar LB. The embodiment of fig. 9 differs slightly from fig. 2: each of the multi-stage photovoltaic modules in fig. 2 is assigned one turn-off device, but fig. 9 shares one turn-off device. The separate shut-off device SD shown in fig. 9 is much less expensive than fig. 2, the position of the shut-off device SD being arbitrary: the photovoltaic module can be arranged between the negative output end Q2 of the last Nth photovoltaic module and the bus bar LB, can also be arranged between the positive output end Q1 of the first photovoltaic module PV1 and the bus bar LA, and can also be arranged between the negative output end of any previous photovoltaic module and the positive output end of the adjacent next photovoltaic module. The general principle is as follows: the multi-stage photovoltaic modules are connected in series to form a battery string and are also connected in series with the shutdown device SD.

Referring to fig. 9, the serial shutdown system as the name implies that the shutdown device SD and the multi-stage photovoltaic module are connected in series, and includes: the shutdown control module RSD and the shutdown device SD, the photovoltaic modules PV1-PVN are connected in series to form a battery string and they are also connected in series with the shutdown device SD, which is used to perform a shutdown operation on the battery string connected in series with it. When the turn-off control module RSD receives the turn-off command, for example, the turn-off command can be expressed by pressing an emergency turn-off switch/turn-off button/touch screen type turn-off switch equipped in the turn-off control module, and the turn-off control module RSD has a human-computer interaction function. The mode in which the shutdown control module RSD issues a so-called shutdown command to the shutdown device SD adopts the following scheme: when the shutdown control module RSD controls the shutdown device SD to be in the normal on state to ensure that the shutdown device SD and the battery string are connected in series, it needs to send the excitation pulse source PUS to the shutdown device SD uninterruptedly or at least intermittently or periodically, and at this time, the battery string including the photovoltaic modules PV1-PVN is directly connected in series between the buses LA-LB because the shutdown device SD is on, so that it can contribute a higher voltage level to the buses; in contrast, if the shutdown control module RSD stops sending the so-called excitation pulse source PUS to the shutdown device SD when the shutdown device SD is in the shutdown state, so that the battery string is removed from between the dc buses LA to LB, the battery string containing the photovoltaic modules PV1 to PVN is itself directly removed from between the buses LA to LB because the shutdown device SD is in the shutdown state, that is, electric energy cannot be further contributed to the buses. The mode in which the shutdown control module instructs shutdown to the shutdown device SD can be roughly considered as: the supply of the periodic excitation pulse source PUS to the shut-down device SD is stopped to inform the shut-down device SD to perform a shut-down operation on the battery string connected in series therewith.

Referring to fig. 9, a first coupling transformer T₁Is connected in series with a main switch M having a first terminal and a second terminal and a control terminal, a signal at the control terminal of the main switch M determining whether the first terminal and the second terminal of the main switch M are on or off, a drive signal output by the processor 80 being coupled to the control terminal of the main switch M and determining whether the main switch is onOr off, the coupling transformer can be replaced by a transformer. First coupling transformer T₁Its secondary winding L2 is then used to extract or inductively switch off the excitation pulse source PUS that the control module RSD loads onto the power line, which may be a pulsating voltage and is most common with square waves, because of the coupling effect. In order to satisfy the condition that the secondary winding L2 can induce and capture the excitation pulse source PUS, a first coupling transformer T₁The synonym terminal of the secondary winding L2 is coupled to the first terminal of the main switch M, i.e. to a common node NCO, which is provided with a reference ground potential GR. First coupling transformer T₁The dotted terminal of the secondary winding L2 is coupled to the predetermined reference terminal NRF through a steering diode D2. Specifically, the method comprises the following steps: first coupling transformer T₁Is coupled to a first node N1 via a first capacitor CC, the steering diode D2 is connected between the first node N1 and a control terminal of the main switch, an anode terminal of the steering diode D2 is connected to the first node N1 and a cathode terminal of the steering diode D2 is connected to a predetermined reference terminal NRF. At the first coupling transformer T₁A first diode D1 is additionally connected between the synonym terminal of the secondary winding L2 and the first node N1, it being noted that the anode of the first diode D1, which has the reference ground GR, is connected to this first coupling transformer T₁The synonym terminal and the cathode of the secondary winding L2 are connected to a first node N1. The excitation pulse source PUS captured or induced by the secondary winding L2 from the power line charges the energy storage capacitor C1 connected between the predetermined reference terminal NRF and the first terminal, i.e., the energy storage capacitor C1 disposed between the predetermined reference terminal NRF and the common node NCO, via the steering diode D2, the steering diode D2 allowing the induced pulse to charge the energy storage capacitor unidirectionally. A parallel resistor R1 connected in parallel with the energy storage capacitor is arranged between the preset reference terminal NRF and the first terminal or the common node NCO, and the energy storage capacitor C1 is charged by the induced excitation pulse source PUS. The main switch M is turned on when the potential of the energy storage capacitor C1 reaches the power restoration condition detectable by the processor 80, otherwise, the main switch M is turned off when the potential of the energy storage capacitor C1 does not reach the power restoration condition detectable by the processor 80. So that the processor detects the stored energyThe main switch is controlled by the processor to switch off when the processor 80 detects a power down condition caused by the cessation of the delivery of the excitation pulse to the shut-off device, at which time the power of the energy storage capacitor drops below an acceptable predetermined voltage level. The processor 80 detects a power restoration condition resulting from the restoration of the supply of the excitation pulse to the turn-off device, the main switch being controlled by the processor to be turned on, and the charge of the energy storage capacitor rising to a level not lower than the predetermined voltage level due to the restoration of the charge. In summary: stopping transmitting the periodic excitation pulse source to the turn-off device to stop supplying power to a processor carried by the turn-off device, and detecting the condition of stopping supplying power by the processor and executing turn-off operation so as to turn off the photovoltaic module corresponding to the turn-off device; or when the turn-off control module receives the starting command, the periodic excitation pulse source is transmitted to the turn-off device again to restore the power supply to the processor carried by the turn-off device, and the processor detects the power restoration condition and executes the conduction operation so as to restore the photovoltaic module corresponding to the turn-off device from the turn-off state to the series connection state.

With reference to fig. 10, the shutdown device SD essentially comprises a main switch M connected in series with the photovoltaic modules PV1-PVN via the power line and a first coupling transformer T₁The first capacitor CC and the first diode D1 are omitted with respect to fig. 9. A first coupling transformer T is provided in the so-called shutdown device SD₁Is connected in series with a main switch M having a first terminal and a second terminal and a control terminal. Wherein the first coupling transformer T₁The secondary winding L2 is used to extract the excitation pulse source PUS applied to the power line, and as a coupling function of the signal, the excitation pulse source PUS signal induced or captured by the secondary winding L2 is charged to the energy storage capacitor C1 connected between the predetermined reference terminal NRF and the first terminal, such as the source electrode, via the steering diode D2. In an alternative embodiment, a parallel resistor R1 is further provided between the predetermined reference terminal NRF and the first terminal or common node NCO, which is connected in parallel with the energy storage capacitor C1. In an alternative embodiment, the steering diode D2 has its anode terminal directly connected to the same name terminal of the secondary winding L2 and its cathode terminal connected to the predetermined reference terminal NRF.Also provided between the preset reference terminal NRF and the first terminal or common node NCO is a pair of anti-series connected zener diodes Z1-Z2 connected in parallel with the energy storage capacitor C1. The reverse series connection of the zener diodes Z1-Z2 means: the anodes of zener diodes Z1 and Z2 are interconnected, the cathode of zener diode Z1 is connected to the first terminal or common node NCO, and the cathode of zener diode Z2 is connected to the control terminal of the main switch such that the pair of series connected zener diodes is connected in parallel with the energy storage capacitor C1, note that this embodiment may also be applied to the embodiment of fig. 9 as well. The back-to-back reverse series connected voltage stabilizing diodes are used for clamping the voltage drop between the control terminal and the first terminal of the main switch, and the power switch is prevented from being damaged. The first terminal of the main switch and the common node are in this application directly coupled together with the same reference ground potential GR.

With reference to fig. 11, by modifying the series shutdown system for photovoltaic modules mentioned above, in particular in the embodiments of fig. 2-10, it comprises: the system comprises a shutdown control module RSD and a shutdown device SD, wherein the photovoltaic modules PV1-PVN are connected in series to form a battery string and are also connected in series with the shutdown device SD, the shutdown device SD is used for performing shutdown operation on the battery string connected in series with the shutdown device SD, and the shutdown control module RSD stops sending a periodic excitation pulse source PUS to the shutdown device to inform the shutdown device SD of performing shutdown operation on the battery string connected in series with the shutdown device SD when receiving a shutdown command. In topology the shutdown device SD comprises a main switch M connected in series with a plurality of photovoltaic modules PV1-PVN via a power line and a coupling element T replacing the first coupling transformer in the foregoing₃In this embodiment, the coupling element T₃An inductor LS is used. And a so-called inductor LS is connected in series with a main switch M having a first terminal, a second terminal and a control terminal. By contrast we know that the first coupling transformer is replaced by an inductor LS. The inductor LS is used for extracting the excitation pulse source PUS loaded on the power line, the induced excitation pulse source PUS charges the energy storage capacitor C1 connected between the preset reference terminal NRF and the first terminal through a steering diode D2, and the energy storage capacitor C1 is charged to the power restoration condition authorized by the processor 80The switch M is switched on or the main switch M is switched off. The actual position of the inductor LS is the position of the primary winding of the first coupling transformer, so that one end of the inductor LS is coupled to the first terminal of the main switch M and the opposite end of the inductor LS is also arranged to be connected to the anode of the steering diode D2, and the cathode of the steering diode is coupled to the predetermined reference terminal NRF. A parallel resistor R1 connected in parallel with the energy storage capacitor is further provided between the preset reference terminal NRF and the first terminal. A pair of anti-series connected zener diodes Z1-Z2 connected in parallel with the energy storage capacitor is also provided between the predetermined reference terminal NRF and the first terminal.

With reference to fig. 11, by modifying the series shutdown system for photovoltaic modules mentioned above, in particular in the embodiments of fig. 2-10, the shutdown device SD is also used to perform the operation of recovering from the shutdown state to the re-series connection state on the string of batteries connected in series therewith, the shutdown control module RSD, upon receiving a start-up command, again delivering a periodic excitation pulse source PUS to the so-called shutdown device SD via the power line to inform the shutdown device SD to perform the re-series connection operation on the string of batteries connected in series therewith. The turn-off device SD comprises a parallel capacitance CP connected between the first and second terminals of the main switch M, in conjunction with fig. 6 and 11. In an alternative embodiment, the shutdown device SD performs a shutdown operation and closes the main switch, and then a parallel capacitor CP connected in parallel with the main switch provides a conduction path for the excitation pulse source PUS to propagate on the power line. The turn-off device SD comprises a normally open parallel switch MP connected between the first and second terminals of the main switch M, in connection with fig. 7 and 11. In an alternative embodiment, the control terminal of the normally-open parallel switch MP is connected to the control terminal of the main switch M, after the shutdown device SD performs the shutdown operation and closes the main switch, the normally-open parallel switch MP entering the conducting state provides a conducting path for the excitation pulse source PUS to propagate on the power line, and when the potential of the energy storage capacitor C1 reaches the power supply recovery condition authorized by the processor 80 and the main switch is turned on, the potential of the energy storage capacitor further controls the normally-open parallel switch MP to be turned off. It is worth mentioning that the various technical features mentioned in all the embodiments of fig. 2 to 10 can be applied to the embodiment of fig. 11, and the shutdown device SD can be connected between the negative output Q2 of the last photovoltaic module PVN and the bus bar LB, and the shutdown device SD can also be arranged between the positive output Q1 of the leading photovoltaic module PV1 and the bus bar LA, and even between the negative output of any previous photovoltaic module and the positive output of the adjacent next photovoltaic module. The inductor LS and the main switch M can be connected in series and then arranged between the negative output terminal Q2 of the last nth-stage photovoltaic module and the bus bar LB, and can be connected in series and then arranged between the positive output terminal Q1 of the first-stage photovoltaic module PV1 and the bus bar LA, and can also be connected in series and then arranged between the negative output terminal of any previous-stage photovoltaic module and the positive output terminal of the adjacent next-stage photovoltaic module, and the purpose of the arrangement is that the turn-off device can meet the requirement of turning off the whole system.

While the present invention has been described with reference to the preferred embodiments and illustrative embodiments, it is to be understood that the invention as described is not limited to the disclosed embodiments. Various alterations and modifications will no doubt become apparent to those skilled in the art after having read the above description. Therefore, the appended claims should be construed to cover all such variations and modifications as fall within the true spirit and scope of the invention. Any and all equivalent ranges and contents within the scope of the claims of the present application should be considered to be within the intent and scope of the present invention.

Claims

1. A parallel shutdown system for a photovoltaic module, comprising:

at least one turn-off control module;

When the turn-off control module receives a starting command, the turn-off control module transmits periodic excitation pulse sources to the turn-off devices again to restore the power supply to the processors of the turn-off devices, and the processors detect the condition of restoring the power supply and execute turn-on operation so as to restore the photovoltaic modules corresponding to the turn-off devices to a series connection state from a turn-off state;

2. A parallel shutdown system for photovoltaic modules as claimed in claim 1 wherein:

3. A parallel shutdown system for photovoltaic modules as claimed in claim 2 wherein:

4. A parallel shutdown system for photovoltaic modules as claimed in claim 2 wherein:

5. A parallel shutdown system for photovoltaic modules as claimed in claim 2 wherein:

6. A parallel shutdown system for photovoltaic modules as claimed in claim 2 wherein:

7. A parallel shutdown system for photovoltaic modules as claimed in claim 2 wherein:

8. A parallel shutdown system for photovoltaic modules as claimed in claim 2 wherein:

9. A parallel shutdown system for photovoltaic modules as claimed in claim 1 wherein:

10. A series shutdown system for a photovoltaic module, comprising:

at least one shutdown control module and at least one shutdown device;

11. The series shutdown system for a photovoltaic module of claim 10, wherein:

12. The series shutdown system for a photovoltaic module of claim 10, wherein:

13. The series shutdown system for a photovoltaic module of claim 10, wherein:

14. The series shutdown system for a photovoltaic module of claim 11, wherein:

15. The series shutdown system for a photovoltaic module of claim 11, wherein:

16. The series shutdown system for a photovoltaic module of claim 10, wherein:

17. The series shutdown system for a photovoltaic module of claim 10, wherein:

18. The series shutdown system for a photovoltaic module of claim 10, wherein: