CN113381388A - Quick turn-off device for photovoltaic system, control method of quick turn-off device and protection system - Google Patents

Quick turn-off device for photovoltaic system, control method of quick turn-off device and protection system Download PDF

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Publication number
CN113381388A
CN113381388A CN202011212049.5A CN202011212049A CN113381388A CN 113381388 A CN113381388 A CN 113381388A CN 202011212049 A CN202011212049 A CN 202011212049A CN 113381388 A CN113381388 A CN 113381388A
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China
Prior art keywords
switch
turn
state
power generation
generation module
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CN202011212049.5A
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Chinese (zh)
Inventor
朱选才
翁炳文
王禹玺
王斌
何成骏
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Delta Electronics Shanghai Co Ltd
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Delta Electronics Shanghai Co Ltd
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Priority to US17/189,473 priority Critical patent/US11532935B2/en
Publication of CN113381388A publication Critical patent/CN113381388A/en
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
    • H02H7/268—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured for dc systems
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
    • H02H7/28—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured for meshed systems
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02S—GENERATION OF ELECTRIC POWER BY CONVERSION OF INFRARED RADIATION, VISIBLE LIGHT OR ULTRAVIOLET LIGHT, e.g. USING PHOTOVOLTAIC [PV] MODULES
    • H02S50/00—Monitoring or testing of PV systems, e.g. load balancing or fault identification
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy

Abstract

The invention provides a quick turn-off device for a photovoltaic system, a control method thereof and a protection system, wherein the quick turn-off device is connected between a photovoltaic power generation module and a photovoltaic inverter and comprises an input port and an output port, and the quick turn-off device comprises: the first end of the first switch is connected to one end of the input port of the quick turn-off device, the second end of the first switch is connected to the first end of the second switch, and the second end of the second switch is connected to the other end of the input port of the quick turn-off device; a third switch and a fourth switch, the third switch being connected between the first terminal of the second switch and one terminal of the output port, the fourth switch being connected between the second terminal of the second switch and the other terminal of the output port; and the controller is used for controlling the on-off of the first switch, the third switch and the fourth switch. The technical scheme for the embodiment of the photovoltaic system can reduce the photovoltaic cut-off protection cost of the photovoltaic system and improve the reliability of the photovoltaic system.

Description

Quick turn-off device for photovoltaic system, control method of quick turn-off device and protection system
Technical Field
The invention relates to the technical field of power electronics, in particular to a quick turn-off device for a photovoltaic system, a control method of the quick turn-off device and a protection system of the quick turn-off device.
Background
At present, the photovoltaic power generation technology is mature and is widely applied at home and abroad. The photovoltaic power generation system comprises a photovoltaic panel, a junction box, an inverter and the like. The photovoltaic panel converts the received solar energy into direct current electric energy, and the inverter converts the direct current electric energy into alternating current electric energy to be sent to a power grid or directly supplied to customers for use.
The photovoltaic panels connected in series and parallel have very high voltage and energy, and in emergency situations such as system installation and maintenance or earthquake and fire, workers may touch the photovoltaic panels and the wires with dangerous voltage, so that electric shock risks exist. Therefore, the photovoltaic system needs to be connected with a quick turn-off device, and the electric shock risk of the workers can be reduced or eliminated only by cutting off dangerous voltage in the operation area of the workers before the workers operate.
A Rapid Shutdown Device (RSD) can cut off the photovoltaic panel, i.e., the photovoltaic power generation module 101, from the photovoltaic system, thereby ensuring personnel safety. In the related art, as shown in fig. 1A, each photovoltaic power generation module is connected to 1 fast turn-off device, and after the outputs of all the fast turn-off devices are connected in series, the outputs are connected to an inverter 103 to form a photovoltaic system. The triggering device 104 is used to control the on and off of the internal switch of the fast turn-off device. When the trigger device controls a switch in the quick turn-off device to be turned on, the photovoltaic array normally outputs power to the inverter, and the inverter converts the power and then merges the power into a power grid or supplies the power to a load; under the installation maintenance or abnormal condition, the staff controls trigger device, and trigger device control quick turn-off device's internal switch disconnection, and high-pressure photovoltaic array divides into several sections low pressure arrays, cuts off dangerous voltage and dangerous energy, reduces or eliminates staff's electric shock risk.
Since each photovoltaic power generation module in the photovoltaic string needs to be connected with 1 fast turn-off device, the cost of the system is relatively high, which will affect the cost benefit of the whole photovoltaic system.
It is to be noted that the information disclosed in the above background section is only for enhancement of understanding of the background of the present invention and therefore may include information that does not constitute prior art known to a person of ordinary skill in the art.
Disclosure of Invention
An object of the present invention is to provide a quick turn-off device for a photovoltaic system and a control method thereof, which overcome one or more of the problems due to the limitations and disadvantages of the related art, at least to some extent.
According to a first aspect of the embodiments of the present invention, there is provided a fast turn-off device for a photovoltaic system, connected between a photovoltaic power generation module and a photovoltaic inverter, including an input port and an output port, the fast turn-off device including: the first end of the first switch is connected to one end of the input port of the quick turn-off device, the second end of the first switch is connected to the first end of the second switch, and the second end of the second switch is connected to the other end of the input port of the quick turn-off device; a third switch connected between a first terminal of the second switch and one terminal of the output port, and a fourth switch connected between a second terminal of the second switch and the other terminal of the output port; the controller is coupled with the control ends of the first switch, the third switch and the fourth switch and is used for controlling the on-off of the first switch, the third switch and the fourth switch so that the quick turn-off device works in a normal state, a bypass state or a turn-off state; when the quick turn-off device works in a normal state, the first switch, the third switch and the fourth switch are all closed, and the second switch is opened; when the quick turn-off device works in a bypass state, the second switch, the third switch and the fourth switch are all closed, and the first switch is opened; when the quick turn-off device works in the turn-off state, the third switch and the fourth switch are both turned off.
In some embodiments, the second switch comprises a diode; and/or the third switch and the fourth switch comprise relays.
In some embodiments, the first switch comprises a semiconductor switch.
In some embodiments, the fast turn-off device further comprises a detection circuit coupled to the photovoltaic power generation module and the controller, for detecting an electrical parameter output by the photovoltaic power generation module and sending the electrical parameter to the controller.
In some embodiments, the fast turn-off device further comprises: and the auxiliary power supply is coupled with the photovoltaic power generation module and used for converting the direct current output by the photovoltaic power generation module and then supplying power to the quick turn-off device.
In some embodiments, the fast turn-off device further comprises: the PLC communication circuit is coupled with the photovoltaic inverter and used for receiving communication signals sent by the photovoltaic inverter and sending the communication signals to the controller.
According to a second aspect of embodiments of the present invention, there is provided a control method of a rapid turn-off device according to the first aspect of the present invention, the control method including: when the rapid turn-off device works in a turn-off state, detecting whether an online signal is received; if the quick turn-off device works in a turn-off state and receives the on-line signal, converting the state of the quick turn-off device into a bypass state; when the rapid turn-off device works in a bypass state, detecting whether the online signal is received or not, and acquiring the electrical parameters of the photovoltaic power generation module; and if the quick turn-off device works in a bypass state, receives the online signal and the power and electricity parameters of the photovoltaic power generation module are higher than a set threshold value, converting the state of the quick turn-off device into a normal state.
In some embodiments, the control method further comprises: and if the quick turn-off device works in a turn-off state and does not receive the on-line signal, keeping the state of the quick turn-off device unchanged.
In some embodiments, the control method further comprises: if the rapid turn-off device works in a bypass state and does not receive the on-line signal, converting the state of the rapid turn-off device into a turn-off state; and if the rapid turn-off device works in a bypass state, receives the online signal and the electrical parameter of the photovoltaic power generation module is lower than or equal to the set threshold, keeping the state of the rapid turn-off device unchanged.
In some embodiments, the control method further includes, when the rapid turn-off device operates in a normal state, detecting whether an online signal is received, and acquiring an electrical parameter of the photovoltaic power generation module; if the quick turn-off device works in a normal state and does not receive the on-line signal, converting the state of the quick turn-off device into a turn-off state; if the rapid turn-off device works in a normal state, receives the on-line signal and the electrical parameter of the photovoltaic power generation module is higher than a set threshold value, keeping the state of the rapid turn-off device unchanged; and if the rapid turn-off device works in a normal state, receives the on-line signal and the electrical parameter of the photovoltaic power generation module is lower than or equal to the set threshold, converting the state of the rapid turn-off device into a bypass state.
In some embodiments, the control method further comprises: receiving the communication signal sent by the PLC communication circuit, wherein the communication signal is sent to the PLC communication circuit by the photovoltaic inverter; the communication signal comprises the online signal.
According to a third aspect of embodiments of the present invention, there is provided a protection system for a photovoltaic system, comprising at least one fast turn-off device, each of said fast turn-off devices comprising an input port and an output port, said photovoltaic system comprising at least one first photovoltaic power generation module and at least one second photovoltaic power generation module, and a photovoltaic inverter; each of the fast turn-off devices comprises: the first end of the first switch is connected to one end of the input port of the quick turn-off device, the second end of the first switch is connected to the first end of the second switch, and the second end of the second switch is connected to the other end of the input port of the quick turn-off device; and a third switch connected between a first terminal of the second switch and one terminal of the output port, and a fourth switch connected between a second terminal of the second switch and the other terminal of the output port; the controller is coupled with the control ends of the first switch, the third switch and the fourth switch and is used for controlling the on-off of the first switch, the third switch and the fourth switch so that the quick turn-off device works in a normal state, a bypass state or a turn-off state; the input port of each fast turn-off device is coupled in parallel to the corresponding first photovoltaic power generation module, and the second photovoltaic power generation module is connected in series with the output port of the fast turn-off device.
In some embodiments, the second switch comprises a diode; and/or the third switch and the fourth switch comprise relays.
In some embodiments, the protection system further comprises: each detection circuit is coupled with the corresponding photovoltaic power generation module and the controller in the corresponding quick turn-off device, and is used for detecting the electrical parameters output by the photovoltaic power generation modules and sending the electrical parameters to the controller.
In some embodiments, the protection system further comprises: each auxiliary power supply is coupled with the corresponding first photovoltaic power generation module and used for converting the direct current of the first photovoltaic power generation module and then supplying power to the corresponding quick turn-off device.
According to the rapid turn-off device for the photovoltaic system, the control method and the protection system of the rapid turn-off device, the first switch, the second switch, the third switch and the fourth switch are arranged in the rapid turn-off device, so that the on and off of the switches can be controlled, the photovoltaic power generation module can be flexibly controlled to be connected to or disconnected from the photovoltaic system, the whole photovoltaic system can be cut off and protected by at least needing one rapid turn-off device to be connected to the photovoltaic system, and the cost is low.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and together with the description, serve to explain the principles of the invention. It is obvious that the drawings in the following description are only some embodiments of the invention, and that for a person skilled in the art, other drawings can be derived from them without inventive effort.
Fig. 1A schematically illustrates a schematic diagram of a photovoltaic system in the related art;
fig. 1B schematically shows a schematic view of a rapid turn-off device in the related art;
fig. 1C schematically shows a schematic view of another rapid turn-off device in the related art;
fig. 2 schematically shows a schematic view of a fast turn-off device for a photovoltaic system according to an embodiment of the present invention;
FIG. 3 schematically illustrates a schematic view of a photovoltaic system of an embodiment of the invention;
fig. 4 schematically shows a schematic view of a fast turn-off device for a photovoltaic system according to another embodiment of the present invention;
fig. 5 schematically shows a schematic view of a fast turn-off device for a photovoltaic system according to yet another embodiment of the present invention;
fig. 6 schematically shows a schematic view of a current path of a fast turn-off device in an off-state according to an embodiment of the present invention;
fig. 7 schematically shows a schematic view of a current path of a fast turn-off device in a bypass state according to an embodiment of the present invention;
fig. 8 schematically shows a schematic view of a current path of a fast turn-off device in a normal state according to an embodiment of the present invention;
fig. 9 schematically shows a flow chart of a control method for a fast turn-off device of a photovoltaic system according to an embodiment of the present invention;
fig. 10 schematically shows a flow chart of a control method for a fast turn-off device of a photovoltaic system according to another embodiment of the present invention;
fig. 11 schematically shows a cycle diagram of three operating states of the quick turn-off device of an embodiment of the present invention;
fig. 12A schematically shows a transition diagram of the off state of the quick turn-off device of one embodiment of the present invention;
fig. 12B schematically shows a transition diagram of the bypass state of the quick shut down device of one embodiment of the present invention;
fig. 12C schematically shows a transition diagram of a normal state of the quick turn-off device of one embodiment of the present invention.
Detailed Description
Example embodiments will now be described more fully with reference to the accompanying drawings. Example embodiments may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of example embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar structures, and thus their detailed description will be omitted.
Although relative terms, such as "upper" and "lower," may be used in this specification to describe one element of an icon relative to another, these terms are used in this specification for convenience only, e.g., in accordance with the orientation of the examples described in the figures. It will be appreciated that if the device of the icon were turned upside down, the element described as "upper" would become the element "lower". When a structure is "on" another structure, it may mean that the structure is integrally formed with the other structure, or that the structure is "directly" disposed on the other structure, or that the structure is "indirectly" disposed on the other structure via another structure.
The terms "a," "an," "the," "said," and "at least one" are used to indicate the presence of one or more elements/components/parts/etc.; the terms "comprising" and "having" are intended to be inclusive and mean that there may be additional elements/components/etc. other than the listed elements/components/etc.; the terms "first," "second," and "third," etc. are used merely as labels, and are not limiting on the number of their objects.
In the related art, the fast turn-off device (RSD) can be divided into two types, the first type is a turn-off type, and the second type is a limited output voltage type.
The first type of RSD is shown in fig. 1B, wherein the switch S0 is typically a semiconductor switch, such as a MOSFET or an IGBT, controlled by the controller 105. Such RSDs can operate in "off" and "normal operation" 2 states:
when S0 is closed, the RSD operates in a "normal operation" state. At the moment, the electric energy generated by the photovoltaic power generation module is output through the RSD and then is connected with the outputs of other RSDs in series, and then the electric energy is transmitted to the photovoltaic inverter and converted into alternating current.
When S0 is open, the RSD operates in an "off" state. At the moment, the output voltage of the photovoltaic power generation module is disconnected by the RSD, so that the output voltage of the whole string of photovoltaic arrays is safe.
The second type of RSD is shown in fig. 1C, wherein the DC/DC converter 106 can convert DC voltage to D C, and generally includes several topologies, such as buck-type buck converter, boost-type boost converter, and boost-type buck boost converter. Such RSDs can operate in "low voltage output" and "normal operation" 2 states:
under the normal working state, the DC/DC converter in the RSD converts the output voltage of the photovoltaic power generation module into the proper voltage required by the system, so that the photovoltaic system can generate power normally.
Under the state of low-voltage output, the DC/DC converter in the RSD converts the voltage of the photovoltaic power generation module into lower voltage output, so that the output voltage of the whole series of photovoltaic arrays is safe voltage. The lower voltage may be 1V.
RSDs as shown in fig. 1B and 1C generally employ semiconductor switches, such as MOSFETs or IGBTs, which have difficulty in achieving both high voltage and low impedance characteristics due to current technology and process level limitations. Therefore, in practical design, devices with lower voltage are adopted, the voltage resistance value of the devices is generally matched with that of single photovoltaic power generation modules, and the problem is caused that corresponding RSD must be installed for each photovoltaic power generation module.
Because each photovoltaic power generation module in the photovoltaic string needs to be connected with 1 quick turn-off device, the system cost is relatively high.
To solve the technical problem, the present exemplary embodiment provides a fast turn-off device for a photovoltaic system, a control method thereof, and a protection system for a photovoltaic system.
As shown in fig. 2, an embodiment of the present invention provides a fast turn-off device for a photovoltaic system, connected between a photovoltaic power generation module and a photovoltaic inverter, including an input port and an output port, the fast turn-off device including a first switch S1, a second switch S2, a third switch S3, a fourth switch S4, and a controller 201.
A first terminal of the first switch S1 is connected to one terminal IN1 of the input port of the fast turn-off device, a second terminal of the first switch S1 is connected to a first terminal of the second switch S2, and a second terminal of the second switch S2 is connected to the other terminal IN2 of the input port of the fast turn-off device.
The third switch S3 is connected between the first terminal of the second switch S2 and the one terminal OUT1 of the output port, and the fourth switch S4 is connected between the second terminal of the second switch S2 and the other terminal OUT2 of the output port.
And the controller 201 is coupled to control terminals of the first switch S1, the third switch S3 and the fourth switch S4 and is used for controlling the on and off of the first switch S1, the third switch S3 and the fourth switch S4, so that the quick turn-off device works in a normal state, a bypass state or an off state.
When the quick turn-off device works in a normal state, the first switch, the third switch and the fourth switch are all closed, and the second switch is opened; when the quick turn-off device works in a bypass state, the second switch, the third switch and the fourth switch are all closed, and the first switch is disconnected; when the quick turn-off device works in the turn-off state, the third switch and the fourth switch are both turned off.
In the rapid turn-off device in the embodiment of the invention, the third switch S3 and the fourth switch S4 are rapid turn-off switches, and the rapid turn-off switches adopt double-switch redundancy, so that the safety and reliability of the turn-off function can be effectively ensured, and the safe turn-off can be continuously realized under the condition of one switch failure.
The first switch S1 and the second switch S2 are bypass switches, and may implement a bypass function in cooperation with the controller 201. When the quick turn-off device works normally, the first switch S1 is closed, the second switch S2 is opened, and at the moment, the photovoltaic power generation current flows through the first switch S1, the third switch S3, the fourth switch S4 and the photovoltaic power generation module connected to the quick turn-off device, so that the photovoltaic power generation module is connected to a photovoltaic system to generate power normally. If the photovoltaic power generation module connected with the rapid turn-off device is abnormal, for example, the power generation is reduced due to the shading of a building, so that the power supply of the rapid turn-off device is insufficient, the abnormal rapid turn-off device can be bypassed, namely, the first switch S1 is opened, the second switch S2 is closed, at the moment, the photovoltaic power generation current can flow through the second switch S2, the third switch S3 and the fourth switch S4, the photovoltaic power generation module connected with the rapid turn-off device cannot pass through, namely, the abnormal photovoltaic power generation module is bypassed from the photovoltaic system, and the whole photovoltaic system can still normally operate. On the other hand, after the abnormal photovoltaic power generation module is bypassed, the photovoltaic power generation current is not provided any more, but the power supply of the rapid turn-off device is not influenced, and the rapid turn-off device can still maintain the normal control related functions.
When the rapid turn-off device for the photovoltaic system provided by the embodiment of the invention is adopted, the rapid turn-off device does not need to be connected to each photovoltaic power generation module in the photovoltaic system, and compared with the photovoltaic system in the prior art, the cost of the system can be effectively reduced. The reason is that the voltage levels of the third switch S3 and the fourth switch S4 in the present invention are matched with the voltage level of the entire string of photovoltaic power generation modules (i.e., the voltage level of the photovoltaic power generation system), and when the third switch S3 and the fourth switch S4 are turned off, the voltage of the entire system can be sustained. In the fast turn-off devices used in the prior art, the voltage level of the switch is matched to the voltage of the individual photovoltaic power generation modules, so that a fast turn-off device must be connected to each photovoltaic power generation module.
In the embodiment of the invention, the quick turn-off device can have various composition structures. As shown in fig. 2, 4 and 5, are rapid shut-off devices having different composition structures, respectively.
IN the fast turn-off device shown IN fig. 2, when one end IN1 of the input terminal of the fast turn-off device is positive and the other end IN2 is negative, the first switch S1 is connected between the positive terminal of the input terminal and the second switch S2.
IN the fast turn-off device shown IN fig. 4, one terminal IN1 of the input terminal of the fast turn-off device is a negative terminal, the other terminal IN2 is a positive terminal, and the first switch S1 is connected between the negative terminal of the input terminal and the second switch S2.
IN the fast turn-off device shown IN fig. 5, when one end IN1 of the input terminal of the fast turn-off device is positive and the other end IN2 is negative, the first switch S1 is connected between the positive terminal of the input terminal and the second switch S2. In addition, the fast turn-off device may further include a fifth switch S5, S5 connected between the negative pole of the input terminal and the second switch S2.
As shown in fig. 2, the quick turn-off device further includes: and the auxiliary power supply 202 is coupled with the first photovoltaic power generation module through the input end of the quick turn-off device, and is used for converting the direct current of the first photovoltaic power generation module and then supplying power to the quick turn-off device. As shown in fig. 2, the auxiliary power supply 202 is also connected to the controller 201 for supplying power to the controller 201.
In addition, the quick-shut down device further includes a PLC communication circuit 203. As shown in fig. 2, the PLC communication circuit 203 is connected to an output terminal of the quick turn-off device, receives a communication signal from the trigger device 305, processes the communication signal, and sends the processed communication signal to the controller 201. The communication signal from the triggering device 305 includes a shutdown signal or an online signal. The triggering device 305 may characterize the operating state of the photovoltaic inverter, and may be integrated within the photovoltaic inverter or may be provided separately.
Meanwhile, each switch in the rapid turn-off device is detected, when a switch fault is detected, the PLC communication circuit can be informed to send fault information of the rapid turn-off device to the photovoltaic inverter 303, and the photovoltaic inverter 303 gives an alarm to inform maintenance personnel.
The first switch may be a semiconductor switch, such as a MOSFET or an IGBT. The second switch may be a diode or a semiconductor switch (e.g., MOSFET or IGBT). When the second switch is a semiconductor switch, the controller is connected with the control end of the second switch to control the on-off of the second switch. The second switch S2 may also be a diode, and when the second switch S2 is a diode, the second switch S2 is turned on in one direction, and does not need to be controlled by the controller 201.
In a preferred embodiment, the third switch and the fourth switch may be relays. The RSD of the related art as shown in fig. 1B and 1C generally employs a semiconductor switch, which has lower safety and reliability after being turned off than a mechanical switch. The embodiment of the invention adopts the reasonable combination of the mechanical switch and the semiconductor device and adopts a unique control mode, thereby realizing the functions of high reliability and quick turn-off.
Specifically, the high-voltage and low-on-resistance characteristics can be realized simultaneously by adopting mechanical switches such as relays and the like, so that higher photovoltaic power generation module string voltage can be blocked by using a single RSD, the RSD does not need to be configured for each photovoltaic power generation module, and the system cost can be obviously saved.
In addition, compared with the traditional RSD in the prior art, the photovoltaic power generation system provided by the invention has the advantages that after the bypass mode is added, the system power generation amount under the scenes of weak illumination, shielding and the like can be effectively improved, and meanwhile, the stability and the reliability of the whole photovoltaic system can be improved.
The rapid turn-off device of the embodiment of the invention further comprises a detection circuit, wherein the detection circuit is coupled with the photovoltaic power generation module and the controller and is used for detecting electric parameters such as current, voltage or power and the like output by the photovoltaic power generation module and sending the electric parameters to the controller. The detection circuit may be disposed inside or outside the fast turn-off device, and this patent is not limited thereto.
As shown in fig. 6, 7 and 8, the current path in the photovoltaic system is indicated by the dashed line with arrows when the fast turn-off device operates in three different states. As shown in fig. 6, the fast turn-off device operates in the off state, and no current flows through the RSD and the photovoltaic power generation module 301. As shown in fig. 7, the quick turn-off device operates in a bypass state, and current flows through the third switch S3, the second switch S2, and the fourth switch S4 without passing through the photovoltaic power generation module 301. As shown in fig. 8, the quick turn-off device operates in a normal state, and current flows through the third switch S3, the first switch S1, the photovoltaic power generation module 301, and the fourth switch S4.
As shown in fig. 9, an embodiment of the present invention provides a control method for a fast turn-off device, where the control method includes:
step S902, when the fast turn-off device is in the turn-off state, detecting whether an online signal is received.
Step S904, if the fast turn-off device is in the turn-off state and receives the on-line signal, the state of the fast turn-off device is converted into the bypass state.
And step S906, when the quick turn-off device works in a bypass state, detecting whether an online signal is received or not, and acquiring the power of the photovoltaic power generation module.
Step S908, if the fast turn-off device is in the bypass state, receives the online signal, and the power of the photovoltaic power generation module is higher than the set threshold, then the state of the fast turn-off device is converted into the normal state.
As shown in fig. 10, in an embodiment of the present invention, when a program is initialized, the fast turn-off device is in a turn-off state, after the initialization is finished, step S1002 is executed to perform signal communication, and then step S1004 is executed to determine whether an online (online) signal is received, and if not, the fast turn-off device enters the turn-off state; if yes, step S1006 is executed to perform power detection of the photovoltaic power generation module.
After the photovoltaic power generation module is detected, step S1008 is executed to perform judgment, if the power of the photovoltaic power generation module is greater than a set threshold, the photovoltaic power generation module enters a normal state, otherwise, the photovoltaic power generation module enters a bypass state, and then the photovoltaic power generation module returns to a communication link after a certain time delay, and then the next round of circular detection is performed.
As shown in fig. 11, 12A, 12B, and 12C, the contents of the cycle change of the fast turn-off device in three states further include:
after step S902, if the fast turn-off device is in the off state and the on-line signal is not received, the state of the fast turn-off device is kept unchanged.
After step S906, if the fast turn-off device is operating in the bypass state and does not receive the online signal, the state of the fast turn-off device is converted into the off state. And if the quick turn-off device works in a bypass state, receives an online signal and the power of the photovoltaic power generation module is lower than or equal to a set threshold value, keeping the state of the quick turn-off device unchanged.
In addition, as shown in fig. 11 and 12C, when the fast turn-off device operates in a normal state, whether an online signal is received or not is detected, and the power of the photovoltaic power generation module is obtained; if the quick turn-off device works in a normal state and does not receive an on-line signal, converting the state of the quick turn-off device into a turn-off state; if the rapid turn-off device works in a normal state, receives an online signal and the power of the photovoltaic power generation module is higher than a set threshold value, keeping the state of the rapid turn-off device unchanged; and if the quick turn-off device works in a normal state, receives an online signal and the power of the photovoltaic power generation module is equal to or lower than a set threshold value, converting the state of the quick turn-off device into a bypass state.
In the embodiment of the invention, the electrical parameters output by the photovoltaic power generation module need to be received. Here, the electrical parameter is obtained by a detection circuit, which may be arranged inside the quick-shut down device or outside the quick-shut down device. .
In the embodiment of the invention, when detecting whether an online signal is received, a communication signal sent by a PLC communication circuit needs to be received, and the communication signal is sent to the PLC communication circuit by a photovoltaic inverter or a trigger; wherein the communication signal comprises an online signal.
Specifically, as shown in fig. 12A, the initial state of the fast turn-off device is an off state, and under certain conditions, there are two switching manners: when receiving the 'off signal (no on-line signal)', the off state is kept; in case an "on-line signal" is received, it will switch to the bypass state.
As shown in fig. 12B, in the bypass state, there are three switching methods under certain conditions: when receiving a 'turn-off signal (no on-line signal)', the switch-off state is switched to; under the condition of receiving low power, namely under the condition that a communication signal of an online signal is received and the photovoltaic panel is detected to have low power, the bypass state is always kept; and when the high-power condition is received, namely the communication signal of the on-line signal is received and the photovoltaic panel is detected to have higher power, the normal state is switched.
As shown in fig. 12C, in the normal state, there are three switching manners under certain conditions: when receiving a 'turn-off signal (no on-line signal)', the switch-off state is switched to; under the condition of receiving low power, namely under the condition that a communication signal of an online signal is received and the photovoltaic panel is detected to have low power, switching to a bypass state; under the condition of receiving a turn-off signal (no on-line signal) + high power, namely, under the condition that a communication signal of the on-line signal is received and the photovoltaic panel power is detected to be higher, the normal state can be kept.
The embodiment of the present invention further provides a protection system for a photovoltaic system, which includes at least one fast turn-off device, where each fast turn-off device includes an input port and an output port, as shown in fig. 3, and the photovoltaic system in which the fast turn-off device of the embodiment of the present invention is located includes at least one first photovoltaic power generation module 301 and at least one second photovoltaic power generation module 302, and a photovoltaic inverter 303. The input port of the fast turn-off device 304 is coupled in parallel to the first photovoltaic power generation module 301; all the second photovoltaic power generation modules 302 are connected in series with the output port of the quick turn-off device.
Each quick turn-off device comprises a controller, and the controller is coupled with the control ends of the first switch, the second switch, the third switch and the fourth switch and is used for controlling the on-off of the first switch, the second switch, the third switch and the fourth switch so as to enable the quick turn-off device to work in a normal state, a bypass state or a turn-off state.
In the embodiment of the invention, the connection position or the number of the quick turn-off devices can be flexibly selected according to the standard and the actual installation requirement. For example, the connection position of the quick turn-off device may be selected as any one of a head-end photovoltaic power generation module, a tail-end photovoltaic power generation module, or an intermediate photovoltaic power generation module of a photovoltaic array composed of photovoltaic power generation modules. In a photovoltaic array, 1 or more fast turn-off devices can be optionally connected.
In an embodiment of the present invention, the protection system further includes at least one detection circuit, and each detection circuit is coupled to the corresponding first photovoltaic power generation module and the controller in the corresponding fast turn-off device, and is configured to detect an electrical parameter output by the first photovoltaic power generation module and send the electrical parameter to the controller.
In an embodiment of the present invention, the protection system further includes at least one auxiliary power source, and each auxiliary power source is coupled to a corresponding first photovoltaic power generation module, and is configured to convert the direct current of the first photovoltaic power generation module and supply power to a corresponding fast turn-off device.
According to the rapid turn-off device for the photovoltaic system and the control method thereof in the embodiment of the invention, the first switch, the second switch, the third switch and the fourth switch are arranged in the rapid turn-off device, so that the on and off of the switches can be controlled, the photovoltaic power generation module can be flexibly controlled to be connected to or disconnected from the photovoltaic system, the whole photovoltaic system can be cut off and protected by at least needing one rapid turn-off device to be connected to the photovoltaic system, and the cost is low.
The quick turn-off device for the photovoltaic system in the embodiment of the invention adopts the combination of the semiconductor switch and the mechanical switch, so that the stability and the reliability of the whole photovoltaic system can be improved.
Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice within the art to which the invention pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.

Claims (15)

1. A quick turn-off device for a photovoltaic system, connected between a photovoltaic power generation module and a photovoltaic inverter, comprising an input port and an output port, characterized in that the quick turn-off device comprises:
the first end of the first switch is connected to one end of the input port of the quick turn-off device, the second end of the first switch is connected to the first end of the second switch, and the second end of the second switch is connected to the other end of the input port of the quick turn-off device;
a third switch connected between a first terminal of the second switch and one terminal of the output port, and a fourth switch connected between a second terminal of the second switch and the other terminal of the output port;
the controller is coupled with the control ends of the first switch, the third switch and the fourth switch and is used for controlling the on-off of the first switch, the third switch and the fourth switch so that the quick turn-off device works in a normal state, a bypass state or a turn-off state;
when the quick turn-off device works in a normal state, the first switch, the third switch and the fourth switch are all closed, and the second switch is opened;
when the quick turn-off device works in a bypass state, the second switch, the third switch and the fourth switch are all closed, and the first switch is opened;
when the quick turn-off device works in the turn-off state, the third switch and the fourth switch are both turned off.
2. The fast turn-off device of claim 1, wherein the second switch comprises a diode; and/or the third switch and the fourth switch comprise relays.
3. The fast turn-off device of claim 1, wherein the first switch comprises a semiconductor switch.
4. The fast turn-off device of claim 1, further comprising a detection circuit coupled to the photovoltaic power generation module and the controller for detecting an electrical parameter output by the photovoltaic power generation module and sending the electrical parameter to the controller.
5. The quick turn-off device of claim 1, further comprising:
and the auxiliary power supply is coupled with the photovoltaic power generation module and used for converting the direct current output by the photovoltaic power generation module and then supplying power to the quick turn-off device.
6. The quick turn-off device of claim 1, further comprising:
the PLC communication circuit is coupled with the photovoltaic inverter and used for receiving communication signals sent by the photovoltaic inverter and sending the communication signals to the controller.
7. A control method for a rapid turn-off device as claimed in any one of claims 1 to 6, the control method comprising:
when the rapid turn-off device works in a turn-off state, detecting whether an online signal is received;
if the quick turn-off device works in a turn-off state and receives the on-line signal, converting the state of the quick turn-off device into a bypass state;
when the rapid turn-off device works in a bypass state, detecting whether the online signal is received or not, and acquiring the electrical parameters of the photovoltaic power generation module;
and if the rapid turn-off device works in a bypass state, receives the online signal and the electrical parameter of the photovoltaic power generation module is higher than a set threshold value, converting the state of the rapid turn-off device into a normal state.
8. The control method according to claim 7, characterized by further comprising:
and if the quick turn-off device works in a turn-off state and does not receive the on-line signal, keeping the state of the quick turn-off device unchanged.
9. The control method according to claim 7, characterized by further comprising:
if the rapid turn-off device works in a bypass state and does not receive the on-line signal, converting the state of the rapid turn-off device into a turn-off state;
and if the rapid turn-off device works in a bypass state, receives the online signal and the electrical parameter of the photovoltaic power generation module is lower than or equal to the set threshold, keeping the state of the rapid turn-off device unchanged.
10. The control method according to claim 7, characterized by further comprising:
when the rapid turn-off device works in a normal state, detecting whether the online signal is received or not, and acquiring the electrical parameters of the photovoltaic power generation module;
if the quick turn-off device works in a normal state and does not receive the on-line signal, converting the state of the quick turn-off device into a turn-off state;
if the rapid turn-off device works in a normal state, receives the on-line signal and the electrical parameter of the photovoltaic power generation module is higher than a set threshold value, keeping the state of the rapid turn-off device unchanged;
and if the rapid turn-off device works in a normal state, receives the on-line signal and the electrical parameter of the photovoltaic power generation module is lower than or equal to the set threshold, converting the state of the rapid turn-off device into a bypass state.
11. The control method according to claim 7, characterized by further comprising:
receiving the communication signal sent by the PLC communication circuit, wherein the communication signal is sent to the PLC communication circuit by the photovoltaic inverter; the communication signal comprises the online signal.
12. Protection system for photovoltaic systems, comprising at least one fast turn-off device, each of said fast turn-off devices comprising an input port and an output port, characterized in that,
the photovoltaic system comprises at least one first photovoltaic power generation module and at least one second photovoltaic power generation module, and a photovoltaic inverter;
each of the fast turn-off devices comprises:
the first end of the first switch is connected to one end of the input port of the quick turn-off device, the second end of the first switch is connected to the first end of the second switch, and the second end of the second switch is connected to the other end of the input port of the quick turn-off device; and
a third switch connected between a first terminal of the second switch and one terminal of the output port, and a fourth switch connected between a second terminal of the second switch and the other terminal of the output port; and the number of the first and second groups,
the controller is coupled with the control ends of the first switch, the third switch and the fourth switch and is used for controlling the on-off of the first switch, the third switch and the fourth switch so that the quick turn-off device works in a normal state, a bypass state or a turn-off state;
the input port of each fast turn-off device is coupled in parallel to the corresponding first photovoltaic power generation module, and the second photovoltaic power generation module is connected in series with the output port of the fast turn-off device.
13. The protection system of claim 12, wherein the second switch comprises a diode; and/or the third switch and the fourth switch comprise relays.
14. The protection system of claim 12, further comprising:
each detection circuit is coupled with the corresponding photovoltaic power generation module and the controller in the corresponding quick turn-off device, and is used for detecting the electrical parameters output by the photovoltaic power generation modules and sending the electrical parameters to the controller.
15. The protection system of claim 12, further comprising:
each auxiliary power supply is coupled with the corresponding first photovoltaic power generation module and used for converting the direct current of the first photovoltaic power generation module and then supplying power to the corresponding quick turn-off device.
CN202011212049.5A 2020-03-09 2020-11-03 Quick turn-off device for photovoltaic system, control method of quick turn-off device and protection system Pending CN113381388A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US17/189,473 US11532935B2 (en) 2020-03-09 2021-03-02 Rapid shutdown device for photovoltaic system and control method thereof and protection system

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CN202010156979 2020-03-09
CN2020101569797 2020-03-09

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