CN113193595B

CN113193595B - Safety management system and safety management method for photovoltaic module

Info

Publication number: CN113193595B
Application number: CN202110516773.5A
Authority: CN
Inventors: 张永
Original assignee: FONRICH NEW ENERGY TECHNOLOGY Ltd SHANGHAI
Current assignee: FONRICH NEW ENERGY TECHNOLOGY Ltd SHANGHAI
Priority date: 2021-05-12
Filing date: 2021-05-12
Publication date: 2023-01-06
Anticipated expiration: 2041-05-12
Also published as: CN113193595A

Abstract

The invention mainly relates to a safety management system and a safety management method of a photovoltaic module. The method comprises the steps that a plurality of photovoltaic modules supply power to a bus in a parallel mode, partial voltage output to the bus and partial current output to the bus are collected at each photovoltaic module through first equipment, second equipment used for collecting total voltage on the bus is configured on the bus, communication is established between the first equipment and the second equipment, and the partial voltage and the partial current of the photovoltaic modules are sent to the second equipment through the configured first equipment. The second equipment compares the partial voltage output to the bus by each photovoltaic module with the total voltage on the bus: and when a difference value exists between the partial voltage at any photovoltaic assembly and the total voltage and the product of the difference value and the partial current at any photovoltaic assembly exceeds an upper limit value, judging that the fault occurs at any photovoltaic assembly.

Description

Safety management system and safety management method for photovoltaic module

Technical Field

The invention mainly relates to the field of photovoltaic power generation, in particular to a mechanism for performing safety management on a direct-current power supply, namely a photovoltaic module, in a photovoltaic power generation system containing the photovoltaic module, which not only ensures that the photovoltaic module operates in a safe and reliable environment, but also can troubleshoot the photovoltaic module.

Background

The photovoltaic module is used as an important core component of a photovoltaic power generation system, the excellent performance of the photovoltaic module directly influences the overall effect of the power generation system, but in practice, the photovoltaic module is subjected to more restriction factors, and the characteristic difference of each photovoltaic module causes the loss of the connection combination efficiency. The photovoltaic device array is generally in series-parallel connection, and if one of the cell devices is subjected to power reduction caused by shadow or dust, or shading or aging, other devices in series-parallel connection may be affected by the reduction of voltage and current intensity. In order to guarantee the safety and reliability of the operation of the photovoltaic array, it is important to fully exert the maximum power generation efficiency of each photovoltaic module and guarantee that the photovoltaic module is in a normal working state.

In many national regions, the rapid switching off of the photovoltaic facilities at the module level has been regarded as a mandatory requirement, and as a china with extremely wide photovoltaic distribution, the standards are not established in the field, and the safety standards fall behind the product manufacturing and market promotion. At present, only the local standard of the entrance of the public security fire-fighting headquarters in Anhui province and province puts forward the standardized requirements. Although the community standards are introduced in Zhejiang and Jiaxing, etc., no mandatory requirement is imposed on the rapid turn-off of the components, and only concepts such as proper provision are provided. The rapid shutdown of the component level is urgently needed to be deeply researched and applied in case of fire of a photovoltaic power station for a plurality of rooftop users at home and abroad. Potential safety risks are more likely to be exposed when photovoltaic is pervaded as a daily rooftop installation. On one hand, the requirements on design specification, construction and acceptance are provided from the aspect of safety awareness to ensure that property and personal safety are guaranteed, on the other hand, the industry is actively promoted to establish a more popular mandatory safety standard as soon as possible, and a photovoltaic module turn-off device suitable for a quick turn-off function is developed.

Photovoltaic power generation systems belonging to the high voltage field should comply with electrical safety regulations. In recent years, for safety reasons, mandatory requirements have been gradually added to relevant electrical specifications in the united states, europe and other countries. Corresponding laws and regulations are respectively set for governments or related organizations. Based on electrical mandatory regulations, the american fire protection association modifies national electrical regulations, specifying among residential photovoltaic power generation systems: when an emergency happens, the voltage of the direct current terminal can not exceed eighty volts to the maximum extent after the alternating current grid-connected end of the photovoltaic power generation system is required to be disconnected. Italian safety regulations caution: firefighters are absolutely not allowed to perform fire extinguishing operations with building live voltage. Germany also has first implemented fire safety standards and also stipulates in plain text: an additional direct current cut-off device is required to be added between an inverter and a component in the photovoltaic power generation system. The power electronic technology of the photovoltaic module level is a main mode for realizing module level shutdown, and application products comprise a micro inverter, a power optimizer and an intelligent control shutdown device. The use of the micro inverter can fundamentally eliminate direct current high voltage existing in a photovoltaic system, and the photovoltaic module power optimizer and the intelligent control shutoff device have a module level shutoff function. The photovoltaic system provided with the power optimizer or the intelligent control breaker under emergency can timely cut off the connection between each module, eliminate the direct current high voltage existing in the array and realize the rapid turn-off of the module level.

Based on the monitoring pressure of the photovoltaic power station on the components, a reasonable monitoring and management mechanism is necessary to be established, and parameter data of the component boards can be extracted from the component boards through the management mechanism and fed back to owners or users. Real-time parameters such as output voltage and current, power and the ambient temperature of the photovoltaic modules need to be monitored in time, and especially abnormal conditions such as damage or aging of the modules need to be monitored in time, so that the monitoring data information can provide a basis for improving and optimizing each photovoltaic module, and the faulty or aged modules can be quickly positioned and repaired in time. Communication problems with photovoltaic module monitoring systems are involved whether attempts are made to achieve active control of the battery module by an external device or to send parameter information of the battery module locally to the external device. The intelligent management of the photovoltaic module comprises safety management, turn-off management, output power management and the like of the photovoltaic module besides conventional working parameter monitoring.

Disclosure of Invention

The application discloses photovoltaic module's safety control method, its characterized in that includes:

supplying power to the bus bars by a plurality of photovoltaic modules in a parallel manner;

collecting the partial voltage output to the bus at each photovoltaic module;

and comparing the partial voltage output to the bus by each photovoltaic module with the total voltage on the bus, and immediately disconnecting the bus when a difference value exists between the partial voltage output to the bus by any photovoltaic module and the total voltage and exceeds a preset value.

The method comprises the following steps: and collecting the partial current output to the bus at each photovoltaic module, and judging that a fault occurs at any photovoltaic module when a difference value exists between the partial voltage output to the bus by any photovoltaic module and the total voltage and the product of the difference value and the partial current output to the bus by any photovoltaic module exceeds an upper limit value.

The method comprises the following steps: each photovoltaic module is provided with a first device for collecting partial voltage and partial current of the photovoltaic module; and a second device arranged on the bus for collecting at least the total voltage on the bus;

communication is established between the first device and the second device, the partial voltage and the partial current of each photovoltaic module are sent to the second device by the first device configured with the partial voltage and the partial current, and the second device judges whether the photovoltaic module has a fault or not.

The method comprises the following steps: when the first device configured with each photovoltaic assembly sends the divided voltage and the divided current to the second device, a time stamp is attached to the data of the divided voltage and the divided current, so that after the bus is disconnected, the divided voltage and the divided current with the time stamp are used for analyzing and judging whether each photovoltaic assembly has a fault or not.

The method comprises the following steps: the partial voltage output by each photovoltaic module to the bus bar is characterized by the output voltage of the first device, and the partial current output by each photovoltaic module to the bus bar is characterized by the output current of the first device.

The method comprises the following steps: the first device comprises a first controller and a first communication module, and the second device comprises a second controller and a second communication module; the first controller of each first device transmits the divided voltage and the divided current of a corresponding photovoltaic module to the second device by using a matched first communication module;

the second controller of the second device receives the divided voltage and the divided current of each photovoltaic module by the second communication module, and determines whether a fault occurs at each photovoltaic module by the second controller.

The method comprises the following steps: the communication mode between the first and second devices includes at least power line carrier communication or wireless communication.

The method comprises the following steps: the first device is selected from any one of a junction box connecting the photovoltaic module to the bus bar, a shut-off device disconnecting the photovoltaic module from the bus bar or reconnecting the disconnected photovoltaic module to the bus bar, and a power optimizer setting the photovoltaic module at a maximum power point.

The method comprises the following steps: the first device is selected from a voltage converter which performs step-down conversion or step-up conversion on the initial voltage provided by the photovoltaic module and then transmits the initial voltage to the bus.

The method comprises the following steps: the second device includes a combiner box or an inverter.

The method comprises the following steps: the faults occurring at the photovoltaic module include at least an insulation fault or a direct current arc fault.

The method comprises the following steps: the second equipment comprises a disconnecting switch arranged on the bus, and the second equipment immediately operates the disconnecting switch to be switched off when judging that the bus needs to be disconnected so as to disconnect the bus and guarantee safety.

The method comprises the following steps: the second equipment comprises a circuit breaker arranged on the bus, and when the second equipment judges that any photovoltaic assembly has a fault, the circuit breaker is immediately operated to be turned off so as to disconnect the bus to guarantee safety.

The application also discloses photovoltaic module's safety control system, its characterized in that includes:

collecting the partial voltage output to the bus and the partial current output to the bus by utilizing first equipment at each photovoltaic module;

a second device is arranged on the bus for collecting at least the total voltage on the bus;

establishing communication between the first device and the second device, wherein the partial voltage and the partial current of each photovoltaic module are transmitted to the second device by the first device configured with the photovoltaic module;

the second equipment compares the partial voltage output to the bus by each photovoltaic module with the total voltage on the bus:

and when a difference value exists between the partial voltage at any photovoltaic assembly and the total voltage and the product of the difference value and the partial current at any photovoltaic assembly exceeds an upper limit value, judging that the fault occurs at any photovoltaic assembly.

The system comprises the following components: the partial voltage output by each photovoltaic module to the bus bar is characterized by the output voltage of the first device paired with the photovoltaic module, and the partial current output by each photovoltaic module to the bus bar is characterized by the output current of the first device paired with the photovoltaic module.

Drawings

In order that the above objects, features and advantages will be readily understood, a more particular description of the invention briefly described above will be rendered by reference to the appended drawings, which are illustrated in the appended drawings.

Fig. 1 shows that photovoltaic modules supply power to a bus in parallel and the bus is provided with an energy collecting device.

Figure 2 is a photovoltaic module configured with a voltage converter to raise or lower the voltage of the photovoltaic module.

Fig. 3 shows that the energy collecting device provided in the bus may be an inverter, a junction box, or the like.

Fig. 4 shows the connection of a photovoltaic module to a bus bar by means of a photovoltaic junction box equipped with a data acquisition module.

Figure 5 is a connection of the photovoltaic module to the bus bar by means of a shortening device equipped with a data acquisition module.

Fig. 6 shows the connection of a photovoltaic module to a bus bar by means of a voltage converter equipped with a data acquisition module.

Fig. 7 shows that the partial voltage, the partial current, etc. of the photovoltaic module are transmitted from the first device to the second device.

Fig. 8 shows that the second device determines whether a fault occurs according to information such as the divided voltage and the divided current of the component.

Detailed Description

The present invention will be described more fully hereinafter with reference to the accompanying examples, which are intended to illustrate and not to limit the invention, but to cover all those embodiments, which may be learned by those skilled in the art without undue experimentation.

Referring to fig. 1, in the field of photovoltaic power generation, a photovoltaic module, that is, a photovoltaic cell, is a core component of power generation, and a solar panel is divided into a monocrystalline silicon cell, a polycrystalline silicon solar cell, an amorphous silicon solar cell, and the like in a mainstream technical direction. The number of photovoltaic modules adopted by a large centralized photovoltaic power station is huge, while the number of photovoltaic modules adopted by a small household small power station in a small scale is relatively small. Silicon substrate photovoltaic modules require service lives in the field of up to more than twenty years, so real-time and permanent monitoring of photovoltaic modules is essential. Many internal and external factors cause the generation efficiency of the photovoltaic module to be low, and factors such as manufacturing difference or installation difference between the photovoltaic modules themselves or shading or maximum power tracking adaptability cause the conversion efficiency of the module to be reduced. Taking a common shadow shielding as an example, if a part of the photovoltaic modules are shielded by clouds or buildings or tree shadows or pollutants and the like, the part of the photovoltaic modules can be changed into a load by a power supply and do not generate electric energy any more, the local temperature of the photovoltaic modules at the position with a serious hot spot effect is usually higher and even exceeds 150 ℃, so that the local area of the modules is burnt or permanently damaged by forming a dark spot, melting a welding spot, aging a packaging body, exploding glass, corroding and the like, great hidden dangers are caused to the long-term safety and reliability of the photovoltaic modules, so that the avoidance of mismatch between the photovoltaic modules is particularly important, and the timely discovery and positioning of faults are more important.

With reference to fig. 1, in terms of a method for the safety management of photovoltaic modules: the plurality of photovoltaic modules P1-PN supply power to the bus in parallel and assuming that the bus comprises a positive bus B1 and a negative bus B2, the positive pole of each of the plurality of photovoltaic modules P1-PN is coupled to the so-called positive bus B1, and correspondingly the negative pole of each of the plurality of photovoltaic modules P1-PN is coupled to the so-called negative bus B2. For example, each photovoltaic module is provided with a photovoltaic junction box, the main function of the photovoltaic junction box in the photovoltaic system is to connect the electric energy generated by the photovoltaic module with an external circuit, and the photovoltaic junction box is allowed to be provided with a bypass diode in some occasions, and when the photovoltaic module generates an abnormality, such as a hot spot effect, the abnormal photovoltaic module can be bypassed through the bypass diode of the photovoltaic junction box.

Referring to fig. 1, let a photovoltaic module P1 be equipped with a first device J1. In the present embodiment, assuming that the first device is a photovoltaic junction box, the positive electrode of the photovoltaic module P1 is connected to the positive bus bar B1 by the first device J1, and the negative electrode of the photovoltaic module P1 is connected to the negative bus bar B2 by the first device J1 according to the connection function of the photovoltaic junction box. In this case, the first device is a connector between the photovoltaic module and the bus bar, and a photovoltaic junction box (PVjunction box) is also called a solar junction box.

Referring to fig. 1, a photovoltaic module PN is equipped with a first device JN. In this embodiment, assuming that the first device is a photovoltaic junction box, the positive electrode of the photovoltaic module PN is connected to the positive bus B1 by the first device JN, and the negative electrode of the photovoltaic module PN is connected to the negative bus B2 by the first device JN according to the connection function of the photovoltaic junction box. It can be seen that the different photovoltaic modules are in parallel and the different first devices are also in parallel, where N is a positive integer greater than 1.

Referring to fig. 1, the divided voltage of the first-stage photovoltaic module P1 is V1. The similar partial voltage output by the second-stage photovoltaic module P2 is denoted as V2. And by analogy, the divided voltage output by the Nth-stage photovoltaic module PN is VN. So that the total bus voltage that any group of photovoltaic modules can provide is about V through calculation _BUS . The output power of each photovoltaic component is superposed on the bus bar, and the power collected by the bus bar is much higher than that of the single photovoltaic component.

Referring to fig. 1, the first apparatus J1 uses a photovoltaic junction box in the present embodiment. The partial voltage V1 output by the photovoltaic module P1 to the bus bar can be characterized by the output voltage of the first device J1, and the partial current output by the photovoltaic module P1 to the bus bar can be characterized by the current I1 output by the first device J1. The first device JN can also be characterized by the output voltage of the first device JN, such as the divided voltage VN output by the photovoltaic module PN to the bus, and the divided current output by the photovoltaic module PN to the bus can be characterized by the current IN output by the first device JN, which is characteristic of the junction box.

Referring to fig. 2, it is assumed that the first device is a voltage converter, such as a voltage converter provided for each of the multi-stage photovoltaic modules P1-PN, and the output power of the voltage converters corresponding to the multi-stage photovoltaic modules P1-PN is required to be superimposed on the dc bus and thereby used as the bus power. In this case, the plurality of voltage converters are connected in parallel with each other. The first device J1, such as a voltage converter, converts the electric energy captured from the corresponding photovoltaic module P1 into its own output power, and the first device J1, such as a voltage converter, further performs processing such as voltage boosting or voltage reducing or voltage boosting on the initial voltage of the corresponding photovoltaic module P1, and then outputs the initial voltage. The DC/DC converter as the voltage converter may be a step-up type voltage converter or a step-up type switching power supply, a step-down type voltage converter or a step-down type switching power supply, a step-up and step-down type voltage converter or a step-up and step-down type switching power supply. The first device has a voltage regulation function of boosting or reducing voltage. According to the same principle, the remaining first devices JN such as the voltage converters convert the electric energy extracted from the corresponding photovoltaic modules PN into their own output power, and the first devices JN such as the voltage converters further perform the processing of boosting, stepping down, or stepping up and stepping down the initial voltage of the corresponding photovoltaic modules PN and then output the initial voltage. The second plant 100 can invert the dc power on the bus to the desired ac power using the inverter INVT, noting that there are a number of other alternative examples of the second plant.

Referring to fig. 2, the first device is a voltage converter that performs voltage conversion on the initial voltage of the component. In the parallel connection relationship, the partial voltage V1 output by the first-stage photovoltaic module P1 to the bus bar can be represented by the output voltage of the first device J1, and the partial current output by the first-stage photovoltaic module to the bus bar can be represented by the current I1 output by the first device J1. The divided voltage V1 is a voltage output by the converter, i.e., the first device J1, after performing conversion such as voltage boosting or voltage dropping. The divided voltage VN output by the nth-stage photovoltaic module PN to the bus may be represented by an output voltage of the first device JN, and the divided current output by any nth-stage photovoltaic module PN to the bus may be represented by a current IN output by the first device JN. The same divided voltage VN is a voltage output by the converter, i.e., the first device JN, after performing conversion such as boosting or stepping down.

Referring to fig. 3, the energy harvesting device used by the second apparatus 100 may be other energy harvesting devices besides the inverter INVT, such as a junction box CB or the like that typically collects energy of photovoltaic modules, and may be various chargers or boost converters or the like that charge storage batteries. The second equipment uses the boost converter can raise the voltage level of the bus, and then carries out inversion conversion on the bus voltage with higher voltage level.

Referring to fig. 4, the data acquisition module is used for acquiring one or more items of target data of the photovoltaic module. The target data collected by the data collection module comprise the initial voltage and the initial current of the photovoltaic module, the partial voltage or the partial current output to the bus by the first device. The data acquisition module may use a voltage detection module, such as a voltage detector VT or a voltage sensor, which is commonly used in the industry, to detect the initial voltage of the photovoltaic device, and a voltage detection module, such as a voltage detector VT or a voltage sensor, which is commonly used, to detect the output voltage of the first device. The initial current of the photovoltaic module can be detected by using a current detection module such as a current detector CT or a current sensor, and the output current of the first device can be detected by using a current detection module such as a current detector CT or a current sensor. The initial voltage and initial current of the photovoltaic module are delivered to the first device and the output voltage and output current of the first device are delivered to the bus. The data acquisition module may also include a temperature sensor for monitoring the ambient temperature in which the photovoltaic module is located, or an irradiance meter for monitoring the effective irradiance of solar illumination of the ambient environment in which the photovoltaic module is located. The target data may also be referred to as operating parameters, and the data types include, but are not limited to, voltage, current, temperature, output power, effective light radiation, etc. of the photovoltaic module.

Referring to fig. 4, the first device JN includes a controller IC1. Many types of controllers IC1 currently have their own data acquisition modules that can collect the aforementioned target data. For example, the controller IC1 is also referred to as a controller and allows it to have a function of a temperature sensor or a voltage current detection module. The controller IC1 may be provided with an additional data acquisition module to collect the target data, provided that it does not have a data acquisition module. Usually, the controller IC1 can send out the target data by controlling the communication module CM1 after acquiring the parameter information such as the target data. The communication mechanism of the communication module CM1 includes two types of wired communication and wireless communication: for example, all existing wireless communication schemes such as WIFI, ZIGBEE, 433MHZ communication, infrared or bluetooth, etc. may be adopted, and for example, a scheme of power line carrier communication may be intentionally adopted. In an alternative embodiment of the present application, the communication module CM1 includes a power line carrier modulator, and the power line carrier modulator is configured to transmit the target data to the data receiving side by means of a power line carrier. A coupling element 10 is shown for coupling a power line carrier emitted by a power line carrier modulator to a bus, the coupling element 10 being, for example, a transformer with a primary secondary winding or, for example, a signal coupler with a coupling coil. The coupling transformer can be used, for example, to transmit a power line carrier to the primary winding and the secondary winding to the bus or bus branch as part of the bus, the carrier being transmitted to the bus by the coupling of the primary and secondary windings. A typical use of a signal coupler with a magnetic ring and a coupling coil is, for example, to pass a bus or a bus branch directly through the magnetic ring of the signal coupler, around which the coupling coil is wound, and to which a power line carrier is fed, which is then induced from the power bus, so that a contactless signal transmission can be carried out. In summary, all signal coupling schemes disclosed in the prior art can be adopted as the coupling element, and injection type inductive coupler technology, cable clamping type inductive coupler technology, switchable full-impedance matching cable clamping type inductive coupler and the like are all alternatives of the application. The general principle is that the controller delivers the target data to the communication module and the communication module transmits the target data to the data receiver through wired or wireless means.

Referring to fig. 4, regarding wired communication and wireless communication, considering that the geographical environment of the photovoltaic module is a building roof or a desert area or a suburban mountain, the wireless communication usually brings high additional expense cost and is inferior in reliability of durability, and after all, the general life of the photovoltaic module is as long as more than twenty years, so the use of power line carrier for communication between the master node and the slave node and between the slave node and the slave node is a preferable option. But also allows the power line carrier signals emitted by different first devices to differ in frequency.

Referring to fig. 4, the second device 100, which includes a controller IC2 and a communication module CM2, also allows for the inclusion of a carrier signal coupling element 20 configured to sense a power line carrier signal from the bus, noting that the first device is sending and loading a power line carrier signal onto the bus at the photovoltaic module, and the second device is sensing and capturing a power line carrier signal back from the bus to the second device. The communication module and the coupling element are sometimes integrated, as they comprise any of the types of rogowski air coil sensors or high frequency sensors, codecs or shunts, etc. It is worth mentioning that the first device is also identical to the second device described above: the wireless communication device has a data receiving function of wired or wireless communication. The same is true of the second device as the first device described above: the wireless communication device has a data transmission function of wired or wireless communication. For example, when the second device actively polls different first devices and requires that the first devices receive polling signals, it is necessary to return the target data collected and stored by itself to the second device, where the second device is equivalent to a master node and the first devices are equivalent to slave nodes. The first device is illustrated and described in this example with the photovoltaic junction box as an optional example, although the wired and wireless communication functions provided in the foregoing for the first and second devices are also applicable to this example.

Referring to fig. 5, in a shutdown apparatus supporting rapid shutdown management of a photovoltaic module, a first device JN, such as a shutdown apparatus, which can control whether the photovoltaic module is shutdown, is taken as an example. The shutdown management goal that the circuit of the first device JN, e.g., the shutdown apparatus, is expected to achieve is to determine whether it is necessary to shutdown the photovoltaic module in time: photovoltaic systems installed or built into buildings must include a quick shut-off function, reducing the risk of electrical shock to emergency personnel. Although the component shutdown apparatus is described by taking the component shutdown apparatus implementing the shutdown function as an example, the component shutdown apparatus actually functionally integrates at least the data acquisition function and the component shutdown function. Explanation about the component shutdown function: the first equipment JN, such as a shutdown device, may disconnect the corresponding photovoltaic module PN from the bus and not supply power to the bus, and the first equipment JN, such as the shutdown device, or reconnects the disconnected photovoltaic module PN to the bus to supply power to the bus again. For example, the positive output of the first device is connected to the positive bus B1 and the negative output of the first device is connected to the negative bus B2.

Referring to fig. 5, the first device JN provides a switch S1 between the negative pole of the photovoltaic module PN and the negative bus B2 or alternatively provides a switch S1 between the positive pole of the photovoltaic module PN and the positive bus B1. The first device JN collects one or more target data of the photovoltaic module through the data collection module, if the target data are found to be abnormal, the controller IC1 can control the first device JN to turn off the photovoltaic module PN, for example, the controller IC1 operates to turn off the switch S1, and the controller IC1 can drive or control the switch S1 to turn off no matter whether the initial voltage or the initial current of the photovoltaic module is abnormal or the partial voltage or the partial current output to the bus by the first device is abnormal. Based on the communication mechanism established between the first device and the second device, if the instruction sent by the second device 100 to the first device JN includes a turn-off instruction, the first device will actively drive or control the switch S1 to turn off when receiving such an instruction. Meanwhile, in other optional embodiments, shutdown management is also supported, for example, the first device J1 supporting fast shutdown of the photovoltaic module P1 is used to operate the turn-off or turn-on of the shutdown switch S1 of the photovoltaic module configuration to control whether the photovoltaic module P1 is turned off or not. And so on, other optional examples also support shutdown management, such as that the first device J2 supporting rapid shutdown of the pv module P2 is used to operate the turn-off or turn-on of the shutdown switch S1 of the pv module configuration to control whether the pv module P2 is turned off or not. The first device is illustrated in this example with the switch-off device as an alternative example, although the wired and wireless communication functions of the first and second devices described above are equally applicable to this example, and the first and second devices have bidirectional communication capabilities.

Referring to fig. 5, the manner in which the second device 100 reads the respective target data of the photovoltaic modules P1 to PN, such as the divided voltage and the divided current to the bus, is: the second device 100 polls the series of first devices J1-JN corresponding to the photovoltaic modules P1-PN in turn, and when the second device 100 polls any one of the first devices, such as JN, the queried first device, such as JN, needs to return the target data of the corresponding photovoltaic module PN to the second device 100. This data reading mode is now described by way of example: when the controller IC2 of the second device 100 queries the first device, such as J1, the controller IC1 of the queried first device, such as J1, needs to return the target data of the photovoltaic module P1 to the controller IC2. Continuing by way of example, this manner of data reading: when the controller IC2 of the second device 100 queries the first device, such as J2, the controller IC1 of the queried first device, such as J2, needs to return the target data of the photovoltaic module P2 to the controller IC2. In summary, such data reading can be considered as: when the second device polls any one of the first devices, the controller of the inquired first device returns target data of a corresponding photovoltaic module, such as a partial voltage and a partial current to the bus bar, to the controller configured by the second device. To avoid confusion, the controller of the first device may be referred to as a first controller and its communication module may be referred to as a first communication module, while the controller of the second device may be referred to as a second controller and its communication module may be referred to as a second communication module. Other alternatives to the controller are: a field programmable gate array or a complex programmable logic device or a field programmable analog gate array or a semi-custom ASIC or processor or microprocessor or digital signal processor or integrated circuit or a software firmware program stored in a memory, etc. The polling-signed data reading method is also applicable to a shutdown device, a power optimizer, a voltage converter and the like besides the illustrated photovoltaic junction box.

Referring to fig. 6, each of the pv modules P1-PN is configured with a voltage converter, also known as a switching regulator, and is most commonly implemented with switching power supply circuit topologies such as buck converter circuit, boost converter circuit, buck-boost converter circuit, etc. The controller IC1 of the first device JN is usually designed as a driving chip, and the controller drives a voltage converter or a converting circuit to convert the input voltage drawn from the photovoltaic module P1 into an output voltage, the voltage converter is also called a power stage circuit, the controller IC1 is also called a power controller, and the controller IC1 is most commonly a power management controller or a power management chip for managing the switching power supply in the industry. This example allows the first device to simply perform a basic step-down or step-up conversion on the initial voltage of the photovoltaic module, for example, the output voltage of the first device is regarded as the partial voltage of the output of the photovoltaic module to the bus, and the initial voltage of the photovoltaic module is supplied to the first device, and the output voltage of the first device is the voltage obtained by stepping-down or stepping-up the initial voltage of the photovoltaic module. The first device does not need power optimization at this time.

With reference to fig. 6, a concern in distributed or centralized photovoltaic power plants is: shadow occlusion causes mismatches among numerous photovoltaic modules. The problem is that the battery output characteristics of the photovoltaic module are represented by the fact that the output voltage and the output current are closely related to external factors such as light intensity and ambient temperature, and the uncertainty of the external factors causes the corresponding voltages of the maximum output power and the maximum power point to change along with the change of the external factors. For example, the power output by the photovoltaic module has randomness and severe fluctuation, and the random uncontrollable characteristic has high probability of causing great impact on the power grid and may also cause negative influence on the operation of some important loads. Based on these doubts, achieving maximum power point tracking of photovoltaic modules in consideration of external factors is a core goal of the industry to maximize energy and revenue.

Referring to fig. 6, the principle and features of a conventional MPPT method for power optimization: for example, in the early output power control for photovoltaic modules, the Voltage feedback method Constant Voltage Tracking is mainly used, and this Tracking method ignores the influence of temperature on the open-circuit Voltage of the solar cell, so the open-circuit Voltage method and the short-circuit current method are proposed, and their common property is basically very similar to the maximum power point of the solar cell. In order to more accurately capture the maximum power point, a disturbance observation method, a duty ratio disturbance method, a conductance increment method and the like are proposed. The disturbance observation method is characterized in that the current array power is measured, then a small voltage component disturbance is added to the original output voltage, the output power is changed, the changed power is measured, the power before and after the change is compared, the power change direction can be known, if the power is increased, the original disturbance is continuously used, and if the power is reduced, the original disturbance direction is changed. The duty ratio disturbance working principle is as follows: the interface between the photovoltaic array and the load generally adopts a voltage converter controlled by a pulse width modulation signal, so that the input and output relationship of the converter can be adjusted by adjusting the duty ratio of the pulse width modulation signal, and the function of impedance matching is realized, and therefore, the magnitude of the duty ratio substantially determines the magnitude of the output power of the photovoltaic cell. The incremental conductance method is a special way to the disturbance observation method, the biggest difference is only in the logical judgment formula and the measurement parameters, although the incremental conductance method still changes the output voltage of the photovoltaic cell to reach the maximum power point, the logical judgment formula is modified to reduce the oscillation phenomenon near the maximum power point, so that the incremental conductance method is suitable for the climate with instantaneous change of the sunlight intensity and the temperature. The actual measurement method, the fuzzy logic method, the power mathematical model, the intermittent scanning tracking method, the optimal gradient method or the three-point gravity center comparison method and the like belong to the most common maximum power point tracking method. Therefore, the MPPT algorithm used in the photovoltaic energy industry is diversified, and repeated description is omitted in the application.

Referring to fig. 6, each of the pv modules P1-PN is configured with a voltage converter, but the voltage converter is not only simple voltage conversion but also has a power optimization function, and is also called an optimizer. Each power optimizer is used to set the initial current and initial voltage of the photovoltaic module corresponding thereto at the maximum power point. For example, a first device J1, such as a power optimizer, is shown as setting its corresponding pv module P1 at the maximum power point, a first device J2, such as a power optimizer, is shown as setting its corresponding pv module P2 at the maximum power point, and a first device JN, such as a power optimizer, is shown as setting its corresponding pv module PN at the maximum power point. The power optimizer performs a power optimization function on the photovoltaic module, and in this example, the controller IC1 of the first device JN may be configured to operate the power optimizer to perform voltage conversion actions such as voltage boosting, voltage dropping, or voltage boosting, so as to set the initial current and the initial voltage of the photovoltaic module, that is, the input voltage and the input current of the first device, to the maximum power point of the photovoltaic module PN. The first device may also be provided with power management functionality to maximize the efficiency of the photovoltaic module.

Referring to fig. 6, the power optimizer is a dc-to-dc converter, also a single component level battery maximum power tracking device. After the single component is optimized to the maximum power by the power optimizer, the collected total power is transmitted to the inverter to be converted from direct current to alternating current, and then the converted total power is supplied to local use or direct grid connection. The inverter may typically be a pure inverter device without maximum power tracking or an inverter device equipped with two-stage maximum power tracking. The main topology of mainstream power optimizers is, for example, conventional BUCK or BOOST or BUCK-BOOST or CUK circuit architectures.

Referring to fig. 7, the photovoltaic modules P1-PN supply power to the bus in parallel, and the partial voltage output to the bus is collected at each of the photovoltaic modules P1-PN, for example, the partial voltage V1 output to the bus is collected by the first device P1 for the photovoltaic module P1, the partial voltage V2 output to the bus is collected by the first device P2 for the photovoltaic module P2, and so on, it can be known that the partial voltage VN output to the bus is collected by the first device PN for the photovoltaic module PN. The partial voltage output by any one photovoltaic module to the bus bar may be the initial voltage of the photovoltaic module itself, but may also be the output voltage output to the bus bar by the first device. The first device P1 sends the divided voltage V1 to the second device 100, the second device P2 also needs to send its divided voltage V2 to the second device 100, the first device P3 needs to send the divided voltage V3 to the second device, and the first device PN needs to send the divided voltage VN to the second device 100. After the second apparatus 100 knows the partial voltage output by each photovoltaic module to the bus, the second apparatus 100 can output the partial voltage output by each photovoltaic module to the bus and the total voltage V on the bus _BUS And comparing or comparing, and when a difference value exists between the partial voltage output to the bus by any photovoltaic module and the total voltage and the difference value exceeds a preset value, immediately disconnecting the bus to ensure safety, wherein abnormal fault events are likely to occur to some photovoltaic modules with the difference values between the partial voltage and the total voltage. The abnormal fault event is most typically a dc arc fault or an insulation fault, etc. Now, the following examples are given: for example, partial voltage V3 and total voltage V assuming that optional photovoltaic module P3 outputs to the bus bar _BUS With a difference between them and exceeding the preset value VTH, the assembly P3 is likely to have a negative abnormal fault event and needs to disconnect the bus immediately. For example, assuming that the optional photovoltaic module PN outputs the partial voltage VN and the total voltage V to the bus _BUS There is a difference between them and the difference exceedsBeyond the preset value VTH, the component PN is likely to have a negative abnormal fault event and needs to immediately disconnect the bus.

Referring to fig. 7, the second device 100 includes a cut-off switch S2 disposed on the bus bar, and the cut-off switch S2 may be disposed on the positive bus bar or the negative bus bar. The second device 100 compares the partial voltage output by each photovoltaic module to the bus with the total voltage on the bus, and when a difference exists between the partial voltage output by any photovoltaic module to the bus and the total voltage and the difference exceeds a preset value, the second device 100 can control the disconnecting switch S2 to be turned off so as to immediately disconnect the bus. The second device 100 includes a controller IC2, the controller IC2 analyzes and determines a relationship between a divided voltage and a total voltage of each photovoltaic module, and if the controller IC2 determines that a difference exists between a divided voltage output to the bus by any one of the photovoltaic modules and the total voltage and the difference exceeds a preset value, the controller IC2 drives the switch S2 to turn off.

Referring to fig. 7, a disadvantage may occur when the bus is disconnected due to an abnormal event occurring in the photovoltaic module, and the disconnection of the bus is equivalent to the disconnection of a power line carrier communication path between the second device and the first device, and at this time, the second device cannot further inquire specific real-time working state and real-time target data of each photovoltaic module, but it is very necessary to disconnect the bus in time on the premise of ensuring safety. The biggest doubt that the second device cannot inquire real-time target data of the photovoltaic modules is that which photovoltaic module fails cannot be accurately judged: because the most urgent thing is to shut down the bus in time no matter which photovoltaic module fails, even though the failure at that time may not be a true failure but a tolerable one. In an alternative embodiment, the first device of each photovoltaic module arrangement transmits its partial voltage and partial current to the second device, and the respective data of the partial voltage and partial current are also time-stamped, so that the time point of each target data is marked.

Referring to fig. 7, a first device J1, configured for example as a photovoltaic module P1, transmits the partial voltage V1 and the partial current I1 of P1 to the second device 100, with a time stamp being marked on the respective data format of the partial voltage V1 and the partial current I1. Although the bus bar is in the open state, the second device 100 knows the partial voltage V1 and the partial current I1 before the bus bar is opened, since the partial voltage and the partial current have a time stamp. IN the same manner, the first device JN marks a time stamp on the respective data format of the partial voltage VN and the partial current IN when transmitting the partial voltage VN and the partial current IN of the PN to the second device 100. Although the bus is IN the open state, the second device 100 knows the partial voltage VN and the partial current IN before the bus is open, because the partial voltage VN and the partial current IN carry the time stamp. Thereby, the controller IC2 of the second apparatus 100 can analyze the voltage and current distribution of all the photovoltaic modules before the bus is disconnected, and then the second apparatus 100 can locate the fault location (calculate which photovoltaic module is faulty) and judge whether the fault occurred is a real fault (unacceptable fault). Therefore, whether each photovoltaic assembly has a fault or not can be analyzed by the time-stamped partial voltage and partial current after the bus bar is disconnected.

Referring to fig. 7, not only the partial voltage output to the bus bar at each photovoltaic module but also the partial current output to the bus bar at each photovoltaic module is collected. For example, the method collects the partial voltage V1 output by the photovoltaic module P1 to the bus and collects the partial current I1 output by the photovoltaic module to the bus. For example, the partial voltage V2 output by the photovoltaic module P2 to the bus and the partial current I2 output by the photovoltaic module to the bus are collected. For example, the partial voltage V3 output to the bus by the photovoltaic module P3 and the partial current I3 output to the bus by the photovoltaic module are collected. For example, the partial voltage V4 output by the photovoltaic module P4 to the bus and the partial current I4 output by the photovoltaic module to the bus are collected. For example, the partial voltage VN output to the bus by the photovoltaic module PN and the partial current IN output to the bus by the photovoltaic module PN are collected. When a difference exists between the partial voltage output to the bus by any photovoltaic module and the total voltage and the product of the difference and the partial current output to the bus by any photovoltaic module exceeds an upper limit value LIM, the fault at any photovoltaic module can be judged. The upper limit value is, for example, the highest tolerable power consumption value. Usually, a reasonable upper limit LIM can be designed in combination with abnormal situations such as insulation fault or dc arc fault.

See FIG. 7For example, suppose that the partial voltage V1 and the total voltage V output by the photovoltaic module P1 to the bus bar _BUS If a difference exists between the first and second devices and the product of the difference and the split current I1 output by the photovoltaic module P1 to the bus exceeds the upper limit value LIM, the controller of the second device can judge that the real fault occurs at the photovoltaic module P1 through calculation. Difference value, i.e. V1 minus V _BUS The multiplication with the partial current I1 output to the busbar results in a product, and the comparison of the product with the upper limit value can be undertaken by the controller IC2.

Referring to fig. 7, for example, it is assumed that the partial voltage VN and the total voltage V output to the bus by the photovoltaic module PN _BUS If a difference exists between the two values and the product of the difference and the split current IN output to the bus by the photovoltaic module PN exceeds the upper limit value LIM, the controller of the second device can judge that the photovoltaic module PN has a real fault through calculation. Difference, i.e. VN minus V _BUS The multiplication with the partial current IN output to the busbar leads to a product, and the comparison of the product with the upper limit value can be undertaken by the controller IC2.

Referring to fig. 7, it is indicated that the first device JN has a data collection module, and the second device 100 may also have a data collection module with the same function, so that the second device 100 may collect the total voltage V on the bus _BUS . If the total voltage V on the bus _BUS Is set by the second device 100 itself, e.g. it needs to convert the total voltage V of the bus when the second device 100 is an inverter _BUS Set to a reasonable dc voltage level, then the data acquisition module is not necessary, since the total voltage V on the bus is _BUS The inverter itself is set by itself, and the inverter is naturally aware of the bus voltage value.

Referring to fig. 8, the safety management system for photovoltaic modules according to the present example includes: the photovoltaic modules P1-PN are used for supplying power to the bus IN a parallel connection mode, and at any photovoltaic module such as PN, the first equipment such as JN collects the partial voltage VN output to the bus by the PN and collects the partial current IN output to the bus by the PN. And at least one bus is provided with a voltage V for collecting the total voltage on the bus _BUS The second device 100. First device JN IN which communication is established between first devices J1-JN and second device 100 and any of photovoltaic modules such as partial voltages VN and partial currents IN of PN are configured by PNTo the second device 100 using wireless or wired communication. The second device 100 outputs the partial voltages, such as V1-VN, respectively, of each photovoltaic module P1-PN to the bus and the total voltage V on the bus _BUS Comparing one by one: and when a difference value exists between the partial voltage at any photovoltaic component and the total voltage and the product of the difference value and the partial current at any photovoltaic component exceeds an upper limit value, judging that the fault occurs at any photovoltaic component. For example, a fault at the photovoltaic module PN is determined when there is a difference between the partial voltage VN at the optional photovoltaic module PN and the total voltage, and the product of the difference and the partial current IN at the photovoltaic module PN exceeds the upper limit LIM, for example, it may be an insulation fault or a dc arc fault.

Referring to fig. 8, the partial voltage V1 and the total voltage V at the optional photovoltaic module P1 _BUS There is a difference between them and the product of the difference and the partial current I1 at the photovoltaic module P1 is denoted R1= (V1-V) _BUS ) And 1. Times.I. The partial voltage V2 and the total voltage V at the photovoltaic module P2 selected optionally in the safety management system according to the same principle _BUS There is a difference between them and the product of the difference and the partial current I2 at the photovoltaic module P2 is denoted R2= (V2-V) _BUS ) And (ii) x I2. The partial voltage V3 and the total voltage V at the optional photovoltaic module P3 in the safety management system according to the same principle _BUS There is a difference between them and the product of the difference and the partial current I3 at the photovoltaic module P3 is denoted R3= (V3-V) _BUS ) And (4) multiplied by I3. Partial voltage VN and total voltage V at optional photovoltaic module PN in safety management system according to same logic _BUS With a difference between them and the product of the difference and the partial current IN at the photovoltaic module PN is denoted RN = (VN-V) _BUS ) XIN. The second device can thus calculate the difference existing between the partial voltage at each photovoltaic module and the total voltage on the busbar, calculate the product of this difference and the partial current at this photovoltaic module, and determine whether the product exceeds the upper limit value.

Referring to fig. 8, in an alternative example, the partial voltage output by each photovoltaic module to the bus bar is characterized by the output voltage of the first device with which it is paired, while the partial current output by each photovoltaic module to the bus bar is characterized by the output current of the first device with which it is paired. In an alternative example, for example, the partial voltage output by the photovoltaic module P1 to the bus bar is characterized by the output voltage V1 of the first device J1 paired therewith, and for example, the partial current output by the photovoltaic module P1 to the bus bar is characterized by the output current I1 of the first device J1 paired therewith. For example, the partial voltage output by the photovoltaic module PN to the bus bar is characterized by the output voltage VN of the first device JN paired therewith, and the partial current output by the photovoltaic module PN to the bus bar is characterized by the output current IN of the first device JN paired therewith. While the initial voltage provided by each photovoltaic module is typically the input voltage of the first device with which it is paired, it is readily understood that the initial current provided by each photovoltaic module is typically the input current of the first device with which it is paired. In an alternative example, the initial voltage provided by the photovoltaic module PN is generally the input voltage of the first device JN paired therewith, and similarly, the initial current provided by the photovoltaic module PN is generally the input current of the first device JN paired therewith. The first device comprises a solar photovoltaic junction box or a photovoltaic module quick turn-off device or a photovoltaic module power optimizer or a voltage converter and the like. In the case of such an embodiment of the switching power supply, the first device may be a DC/AC inverter voltage converter in addition to the DC/DC voltage converter described above.

Referring to fig. 8, the accidents of arcing and firing caused by poor contact, aging, short circuit, etc. are more and more frequent, and detection of visible dc arc faults is increasingly important in photovoltaic systems. Once a photovoltaic system has a direct current arc fault, the fault arc of the system has a stable combustion environment because zero crossing point protection is not provided and the photovoltaic module generates continuous energy under the irradiation of sunlight. If measures are not timely and effectively taken, high temperature phenomena of more than thousands of degrees can be generated, fire disasters can be caused, and certain substances are melted and even evaporated to generate a large amount of toxic gases, so that the life safety of people is endangered, and the social economy is greatly lost.

Referring to fig. 8, dividing the arc into a direct current arc and an alternating current arc may be roughly classified according to the nature of the current. The well-known alternating current application time is earlier, and alternating current fault arcs exist mature detection methods and commercial products, however, the starting time of a photovoltaic system is later, and the nature characteristics of a direct current arc are different from that of alternating current, and a zero-crossing point characteristic exists in a typical situation that direct current does not have alternating current, so that the alternating current arc detection means cannot be applied to photovoltaic occasions. The variables influencing the electrical properties of the direct current arc are various, and the arc is more complicated due to different photovoltaic use environments. It is generally recognized in the industry that it is difficult to establish a mathematical model of the dc arc, and although some arc models are mentioned, these simplified models are usually studied based on some single characteristics or several very limited characteristics of the arc, and in fact, the noise inevitably existing in the photovoltaic environment and the sporadic interference of the power system are very likely to mislead the arc detection, which results in erroneous detection results, and the dynamically changing light intensity and ambient temperature and the switching noise existing in a large amount are the interference sources for misjudgment and missing judgment. One of the objectives of the present application is to detect real dc arc faults existing in a photovoltaic system to avoid serious accidents such as fire caused by fault arcs.

Referring to fig. 8, the main reasons for the poor detection capability of the conventional arc detection means are: one or more sets of fault arc parameter characteristics need to be worked out in advance, then the actually detected current parameter information is compared with the fault arc parameter characteristics, if the actually detected current parameter information accords with the fault arc parameter characteristics, a real arc event is considered to occur, otherwise, if the actually detected current parameter information does not accord with the fault arc parameter characteristics, the real arc event is considered not to occur. The biggest defect is that the power system of each scene to be detected is different, and the inverter model of each scene to be detected is also different, so that the traditional fault arc detection means always has detection errors or even errors, and the inherent defects are almost irresistible.

Referring to fig. 8, it is noted that an arc event is not necessarily a highly dangerous dc arc fault. Actions such as plugging and unplugging a switch or rotating a motor can cause arcing in a power system, but such arcing does not persist but is transient and does not adversely affect the normal operation of the system and equipment, and such arcing is referred to as good arcing, i.e., normal arcing. Besides normal electric arcs, electric arcs which are caused by short circuit of lines, insulation aging, poor contact of lines and the like, can continuously burn and are easy to ignite surrounding inflammable substances are called bad arcs, namely direct-current fault arcs. The traditional technology does not provide a good solution for discriminating whether an arc event is a normal arc or a direct-current fault arc, and the discrimination of the good arc or the bad arc is a problem to be solved urgently.

Referring to fig. 8, if the communication mode between the first device and the second device adopts power line carrier communication, a power line carrier signal carrying target data such as a partial voltage or a partial current is propagated through a medium such as a bus. In the foregoing, the product is obtained by multiplying the difference value by the divided current output to the bus, and then the product is compared with the upper limit value, so that whether a fault occurs at the photovoltaic module can be better discriminated, but a relatively difficult problem is faced. The main reason is that the initial voltage and current provided by the photovoltaic module are influenced by comprehensive factors such as illumination radiation intensity, ambient temperature, whether shielding exists, shielding degree, aging state of the photovoltaic module and the like, and the comprehensive factors are dynamically changed all the time, so that the fault event is identified from the angle of voltage and current, and the problems of error and inaccurate judgment are difficult to avoid. In an alternative embodiment, a precondition for determining whether the photovoltaic module is faulty needs to be set: when a difference value exists between the partial voltage output to the bus by any photovoltaic module and the total voltage and the product of the difference value and the partial current output to the bus by any photovoltaic module exceeds an upper limit value, the fault at any photovoltaic module can be preliminarily judged; and the rest photovoltaic modules which do not meet the precondition are directly judged to be not failed. The second device further confirms the attenuation degree of the power line carrier signal sent by the first device paired with any photovoltaic module, and synchronously confirms the attenuation degree of the power line carrier signal sent by the first device paired with other photovoltaic modules which do not have faults; if the attenuation degree of the power line carrier signal sent by the first equipment matched with any one failed photovoltaic module is preliminarily judged to be greater than the attenuation degree of the power line carrier signal sent by the first equipment matched with the photovoltaic module which is not failed, the fact that any one photovoltaic module is actually failed can be finally judged and verified; otherwise, a false failure has occurred. For example, an arc generated in a photovoltaic power generation system can be classified into a normal arc and an abnormal arc. An arc caused by an operation such as normal shutdown of the circuit breaker is a normal arc, and an arc caused by a failure such as wire aging or contact failure is an abnormal arc, which means that the arc detection is to correctly distinguish between a good arc and a bad arc. The detection of a dc arc fault is readily solved because of the complex factors that often present a major challenge to dc arc fault detection, such as the presence of a true fault representing an abnormal arc, a so-called bad arc, or a false fault representing a normal arc, a so-called good arc. The preliminary determination of the output voltage level of the first device paired with the failed pv module may negatively interfere with the operation of the first device paired with the non-failed pv module, for example, the former may cause the latter to generate a reverse current or cause the latter to be nearly unable to maintain the output power of the corresponding pv module at the maximum power point. Therefore, in another alternative example, a precondition for determining whether the photovoltaic module is faulty needs to be set: when a difference exists between the partial voltage output to the bus by any photovoltaic module and the total voltage, and the product of the difference and the partial current output to the bus by any photovoltaic module exceeds an upper limit value, the fault at any photovoltaic module can be preliminarily judged. In this alternative example, based on the preconditions: and the other photovoltaic modules which do not meet the precondition are regarded as not having faults, and the second equipment detects the attenuation degree of the power line carrier signal sent by the first equipment paired with the photovoltaic modules which do not have faults. On the premise that the difference value between the partial voltage output to the bus by each photovoltaic module and the total bus voltage does not exceed the preset value, the attenuation degree of the power line carrier signal sent by any first device is regulated to not exceed an attenuation threshold value. When the second device detects that the attenuation degree of the power line carrier signal sent by the first device of the photovoltaic module pair which does not have the fault exceeds a so-called attenuation threshold value, finally judging and verifying that any photovoltaic module is actually in fault; otherwise, a false failure occurs. In an optional, but not necessary, embodiment, the controller of the second device can calculate the attenuation level after receiving the power line carrier signal sent by the controller of the first device and the communication module thereof.

Referring to fig. 8, the advantage of the present application is obvious, and the divided voltage output to the bus by each photovoltaic module P1-PN is compared with the total voltage on the bus to primarily ensure the safety of the system: and when a difference value exists between the partial voltage output to the bus by any photovoltaic module and the total voltage and exceeds a preset value, immediately disconnecting the bus. At this time, whether there is a real fault or a false fault in the system, the disconnection of the bus bar means that the entire power generation system is safe. Then whether the fault is a real fault is discriminated and the fault position is further positioned on the premise of safety: when a difference exists between the partial voltage output to the bus by any photovoltaic module and the total voltage and the product of the difference and the partial current output to the bus by any photovoltaic module exceeds an upper limit value, the fault of any photovoltaic module is judged. The safety management system and the safety management method applied to the photovoltaic module can efficiently identify insulation faults and arc faults and achieve safety targets.

While the above specification concludes with claims defining the preferred embodiments of the invention that are presented in conjunction with the specific embodiments disclosed, it is not intended to limit the invention to the specific embodiments disclosed. 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 should be considered to be within the intent and scope of the present invention.

Claims

1. A safety management method for a photovoltaic module is characterized by comprising the following steps:

collecting the partial voltage output to the bus at each photovoltaic module;

comparing the partial voltage output to the bus by each photovoltaic module with the total voltage on the bus, and immediately disconnecting the bus when a difference value exists between the partial voltage output to the bus by any photovoltaic module and the total voltage and the difference value exceeds a preset value;

each photovoltaic module is provided with at least one first device for collecting partial voltage and partial current of the photovoltaic module; and a second device arranged on the bus at least for collecting the total voltage on the bus; establishing power line carrier communication between first equipment and second equipment, transmitting the partial voltage and the partial current of each photovoltaic module to the second equipment by the first equipment configured with the partial voltage and the partial current, and judging whether the photovoltaic module has a fault or not and judging whether the fault package has a direct current arc fault by the second equipment;

collecting partial current output to the bus at each photovoltaic module, and preliminarily judging that any photovoltaic module has a fault and the rest photovoltaic modules are judged to have no fault when a difference value exists between partial voltage output to the bus by any photovoltaic module and the total voltage and the product of the difference value and the partial current output to the bus by any photovoltaic module exceeds an upper limit value;

the second equipment further confirms the attenuation degree of the power line carrier signal sent by the first equipment matched with any one photovoltaic assembly, and synchronously confirms the attenuation degrees of the power line carrier signals sent by the first equipment matched with the rest photovoltaic assemblies which do not have faults; if the attenuation degree of the power line carrier signal sent by the first equipment paired with any one failed photovoltaic module is preliminarily judged to be greater than the attenuation degree of the power line carrier signal sent by the first equipment paired with the photovoltaic module not failed, finally, the fact that any one photovoltaic module is actually failed is judged and verified; otherwise, a false failure has occurred.

2. The method of claim 1, wherein:

the first device comprises a first controller and a first communication module, and the second device comprises a second controller and a second communication module;

the first controller of each first device transmits the divided voltage and the divided current of the corresponding photovoltaic module to the second device by using the matched first communication module;

3. The method of claim 1, wherein:

the first device is selected from: the photovoltaic junction box connecting the photovoltaic module to the bus bar, the shutdown device disconnecting the photovoltaic module from the bus bar or reconnecting the photovoltaic module in the disconnected state to the bus bar, the power optimizer setting the photovoltaic module at its maximum power point, the voltage converter performing voltage conversion on the initial voltage of the photovoltaic module.

4. The method of claim 1, wherein:

the second device is selected from any one of the combiner box or the inverter.

5. The method of claim 1, wherein:

the second equipment comprises a disconnecting switch arranged on the bus, and the second equipment immediately operates the disconnecting switch to be switched off when judging that the bus needs to be disconnected so as to disconnect the bus and guarantee safety.

6. A safety management system for photovoltaic modules, comprising:

establishing power line carrier communication between the first equipment and the second equipment, and sending the partial voltage and the partial current of each photovoltaic module to the second equipment by the first equipment configured by the photovoltaic module;

when a difference value exists between the partial voltage at any one photovoltaic assembly and the total voltage and the product of the difference value and the partial current at any one photovoltaic assembly exceeds an upper limit value, the fault at any one photovoltaic assembly is preliminarily judged, while the other photovoltaic assemblies are judged not to have the fault, and the fault includes a direct current arc fault;

the second equipment further confirms the attenuation degree of the power line carrier signal sent by the first equipment matched with any one photovoltaic assembly, and synchronously confirms the attenuation degrees of the power line carrier signals sent by the first equipment matched with the rest photovoltaic assemblies which do not have faults; if the attenuation degree of the power line carrier signal sent by the first equipment matched with any one failed photovoltaic module is preliminarily judged to be greater than the attenuation degree of the power line carrier signal sent by the first equipment matched with the photovoltaic module which is not failed, finally, the fact that any one photovoltaic module is actually failed is judged and verified; otherwise, a false failure has occurred.

7. The safety management system of a photovoltaic module according to claim 6, characterized in that:

the first controller of each first device transmits the divided voltage and the divided current of the corresponding photovoltaic assembly to the second device by using the matched first communication module;

8. The safety management system of a photovoltaic module according to claim 6, characterized in that:

9. The safety management system of a photovoltaic module according to claim 6, characterized in that:

the second device is selected from any one of the combiner box or the inverter.

10. The safety management system of a photovoltaic module according to claim 6, characterized in that: