Photovoltaic shutdown devices, inverters, and quick shutdown systems for photovoltaics, and starting methods for them.

Abstract

Invention details;

Description

Photovoltaic module shutoff device, inverter, photovoltaic rapid shutdown system and startup method thereof

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on March 23, 2021, with application number 202110307918.0 and invention name “Photovoltaic module shutdown device, inverter, photovoltaic rapid shutdown system and starting method thereof”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the technical field of photovoltaic grid-connected power generation, and in particular to a photovoltaic module circuit breaker, an inverter, a photovoltaic rapid shutdown system and a startup method thereof. Background Art

[0003] With the continuous development of new energy technologies, photovoltaic power generation technology has also gained widespread application. The photovoltaic arrays in a photovoltaic system output direct current (DC), which is converted to AC by an inverter and then transmitted to the grid. To increase the output power of a photovoltaic system, multiple photovoltaic strings are typically connected in parallel before being connected to an inverter. A circuit breaker is installed on each branch between the photovoltaic array and the inverter to promptly disconnect the string in the event of a safety fault or connect it when grid-connected power generation is required, thereby improving the safety of the photovoltaic system.

[0004] Currently, the activation of photovoltaic panel circuit breakers is mainly achieved by receiving heartbeat communication signals continuously sent by a central controller, or by receiving periodic excitation pulse sources sent by a shutdown control module located on the DC bus. However, this requires the installation of additional receiving modules in the photovoltaic panel circuit breakers, which undoubtedly increases the hardware cost of the photovoltaic panel circuit breakers.

[0005] Summary of the Invention

[0006] The present application provides a photovoltaic module shutoff device, an inverter, a photovoltaic rapid shutdown system and a startup method thereof, in order to solve the problem that the existing method of shutting down the photovoltaic module shutoff device requires the provision of an additional receiving module, resulting in excessively high hardware costs for the photovoltaic module shutoff device.

[0007] To achieve the above objectives, the present invention provides the following technical solutions:

[0008] In a first aspect, the present application discloses a method for starting a photovoltaic rapid shutdown system, wherein a plurality of photovoltaic strings are connected in parallel on the DC side of an inverter in the photovoltaic rapid shutdown system; the method for starting the photovoltaic rapid shutdown system comprises:

[0009] After each photovoltaic module shutoff device in the photovoltaic fast shutdown system is initially started, each photovoltaic module shutoff device that is successfully started enters an unrestricted output state;

[0010] Each photovoltaic component circuit breaker that fails to start or is disconnected again detects the electrical parameters of its output end in real time and determines whether the electrical parameters meet the preset starting conditions. If the electrical parameters meet the preset starting conditions, it controls itself to start again and enter the unrestricted output state.

[0011] Optionally, in the above-mentioned method for starting the photovoltaic rapid shutdown system, the electrical parameter is voltage, and determining whether the electrical parameter meets a preset starting condition includes:

[0012] Determining whether the voltage is greater than or equal to a set threshold after a preset time;

[0013] If the detection result is yes, it is determined that the electrical parameter meets the preset starting condition.

[0014] Optionally, in the above-mentioned method for starting the photovoltaic rapid shutdown system, determining whether the electrical parameter meets a preset starting condition includes:

[0015] Determining whether the electrical parameter has a first preset disturbance;

[0016] If the detection result is yes, it is determined that the electrical parameter meets the preset starting condition.

[0017] Optionally, in the above-mentioned starting method of the photovoltaic rapid shutdown system, the electrical parameter is: voltage or a combined signal of voltage and current.

[0018] Optionally, in the above-mentioned startup method of the photovoltaic rapid shutdown system, the first preset disturbance is: when the inverter in the photovoltaic rapid shutdown system determines that at least one photovoltaic string on its own DC side is in an abnormal state after startup, any one of the voltage, current, and combined signals of voltage and current on its own DC side is applied.

[0019] Optionally, in the above-mentioned startup method of the photovoltaic rapid shutdown system, the abnormal state is a state where the output current / power is zero.

[0020] Optionally, in the above-mentioned method for starting the photovoltaic rapid shutdown system, the first preset disturbance is:

[0021] A persistent disturbance for a predetermined period of time; or

[0022] A continuous disturbance or an intermittent disturbance that exists all the time.

[0023] Optionally, in the above-mentioned startup method of the photovoltaic fast shutdown system, when the electrical parameter is a voltage signal, the first preset disturbance is a double frequency ripple.

[0024] Optionally, in the above-mentioned method for starting the photovoltaic rapid shutdown system, after determining whether the electrical parameters meet the preset starting conditions, the method further includes:

[0025] If the electrical parameters do not meet the preset start-up conditions, the control unit continues to maintain the output limiting state.

[0026] Optionally, in the above-mentioned method for starting the photovoltaic rapid shutdown system, the process of initial starting of each photovoltaic module shutdown device is as follows:

[0027] After each of the photovoltaic assembly circuit breakers determines that the electrical parameters of its own output end have a second preset disturbance, it controls itself to start and enter an unrestricted output state.

[0028] Optionally, in the above-mentioned startup method of the photovoltaic fast shutdown system, the second preset disturbance is: a periodic preset pulse.

[0029] The second aspect of the present application discloses a photovoltaic module shutoff device, comprising: a switch unit, a starting voltage module, a drive circuit, a processor, a bypass diode, and a parameter acquisition unit; wherein:

[0030] The switch unit is provided on the positive branch or the negative branch of the photovoltaic module circuit breaker, and is used to realize the opening or closing of the photovoltaic module circuit breaker according to the control of the processor;

[0031] The parameter acquisition module is used to acquire electrical parameters of the output end of the photovoltaic module circuit breaker and output the electrical parameters to the processor;

[0032] The starting voltage module is configured to output a starting voltage to an output terminal of the photovoltaic module shutoff device according to the control of the processor when the photovoltaic module shutoff device is shutoff and in a normal state;

[0033] The bypass diode is used to realize the bypass function of the photovoltaic module switch when the photovoltaic module switch is turned off;

[0034] The output end of the processor is connected to the control end of the switch unit through the drive circuit; the processor is used to execute the startup method of the photovoltaic fast shutdown system as disclosed in the first aspect.

[0035] Optionally, in the above photovoltaic assembly circuit breaker, the switch unit includes two switch tubes connected in series, and both of the two switch tubes are controlled by the processor through the drive circuit.

[0036] The third aspect of the present application discloses an inverter, comprising: a sampling circuit, an inverter circuit, a signal conditioning circuit and a controller; wherein:

[0037] The sampling circuit is provided on the DC side of the inverter and is used to sample the voltage on the DC side of the inverter and the output current / power of each photovoltaic string connected in parallel thereto;

[0038] The output end of the sampling circuit is connected to the input end of the controller through the signal conditioning circuit;

[0039] The controller is used to control the operation of the inverter circuit to achieve grid-connected power generation and / or apply corresponding disturbances to its DC side, so that each photovoltaic component circuit breaker in each photovoltaic string can execute the startup method of the photovoltaic rapid shutdown system disclosed in the first aspect of claim 1.

[0040] Optionally, in the above inverter, it further comprises: a Boost circuit provided in the front stage of the inverter circuit;

[0041] The input end of the Boost circuit serves as the DC side of the inverter.

[0042] A fourth aspect of the present application discloses a photovoltaic rapid shutdown system, comprising: the inverter disclosed in the third aspect, and a plurality of photovoltaic strings connected in parallel on its DC side;

[0043] The photovoltaic string includes multiple photovoltaic component circuit breakers as disclosed in the second aspect of the right, the output ends of each photovoltaic component circuit breaker are connected in series as the two ends of the photovoltaic string, and the input ends of each photovoltaic component circuit breaker are respectively connected to corresponding photovoltaic components.

[0044] Based on the startup method of the photovoltaic rapid shutdown system provided in the above-mentioned embodiment of the present application, a plurality of photovoltaic strings are connected in parallel to the DC side of the inverter in the photovoltaic rapid shutdown system. According to the method, after the initial startup of each photovoltaic module shutdown device in the photovoltaic rapid shutdown system, each photovoltaic module shutdown device that has successfully started enters an unrestricted output state. Each photovoltaic module shutdown device that fails to start or is disconnected again detects the electrical parameters of its output terminal in real time and determines whether the electrical parameters meet the preset startup conditions. If the electrical parameters meet the preset startup conditions, it controls itself to restart and enter the unrestricted output state. That is, the photovoltaic module shutdown device in this solution can determine whether it meets the preset startup conditions only by using its own existing sampling device, and restart itself after determining that it meets the preset startup conditions. Compared with the existing startup method, there is no need to add corresponding receiving equipment, which reduces the hardware cost of the photovoltaic module shutdown device. In addition, the startup control of the photovoltaic module shutdown device can be achieved without using communication means such as PLC. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0046] FIG1 is a flow chart of a method for starting a photovoltaic rapid shutdown system provided in an embodiment of the present application;

[0047] FIG2 is a flow chart of determining whether electrical parameters meet preset start-up conditions according to an embodiment of the present application;

[0048] FIG3 is another flowchart of determining whether electrical parameters meet preset start-up conditions according to an embodiment of the present application;

[0049] FIG4 is a flow chart of another method for starting a photovoltaic rapid shutdown system provided in an embodiment of the present application;

[0050] FIG5 is a schematic structural diagram of a photovoltaic module circuit breaker provided in an embodiment of the present application;

[0051] FIG6 is a schematic structural diagram of an inverter provided in an embodiment of the present application;

[0052] FIG7 is a schematic structural diagram of a photovoltaic rapid shutdown system provided in an embodiment of the present application;

[0053] FIG8 is a waveform diagram of a double frequency ripple provided in an embodiment of the present application;

[0054] FIG9 is a waveform diagram of a double frequency ripple of a continuous disturbance provided by an embodiment of the present application;

[0055] FIG10 is a waveform diagram of a double frequency ripple of intermittent disturbance provided in an embodiment of the present application. DETAILED DESCRIPTION

[0056] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0057] In this application, the terms "comprises," "comprising," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not preclude the presence of additional identical elements in the process, method, article, or apparatus that includes the element.

[0058] The embodiments of the present application provide a method for starting a photovoltaic rapid shutdown system to solve the problem that the existing method of shutting down a photovoltaic module circuit breaker requires the provision of an additional receiving module, resulting in excessively high hardware costs for the photovoltaic module circuit breaker.

[0059] Referring to Figure 7 , the PV rapid shutdown system primarily comprises an inverter 301 and multiple PV strings 302 connected in parallel on its DC side. Each PV string 302 includes multiple PV module disconnectors 202 . The outputs of each PV module disconnector 202 are connected in series to form the ends of the PV string 302 , while the inputs of each PV module disconnector 202 are connected to corresponding PV modules 201 .

[0060] Based on the photovoltaic rapid shutdown system shown above, referring to FIG1 , another embodiment of the present application provides a method for starting the photovoltaic rapid shutdown system. After the initial startup of each photovoltaic module circuit breaker in the photovoltaic rapid shutdown system, the method mainly includes the following steps:

[0061] S101. The successfully started photovoltaic module circuit breakers enter an unrestricted output state.

[0062] In practical applications, the initial startup of each photovoltaic module circuit breaker in a photovoltaic rapid shutdown system refers to the first startup in the process of switching the photovoltaic module circuit breaker from a limited output state to an unrestricted output state.

[0063] Specifically, the initial activation process of each photovoltaic module circuit breaker is as follows: after each photovoltaic module circuit breaker determines that the electrical parameters at its own output terminal have a second preset disturbance, it controls itself to activate and enter an unrestricted output state. The second preset disturbance is a periodic preset pulse.

[0064] In other words, the initial activation of each PV module circuit breaker in the PV rapid shutdown system is achieved by periodically short-circuiting the inverter's DC side, generating periodic preset pulses. The voltage on the inverter's DC side during this periodic short-circuit is as follows: when the inverter's DC side is short-circuited, the voltage on the DC bus in the PV rapid shutdown system is zero; when the inverter's DC side is not short-circuited, the voltage on the DC bus is the PV string voltage.

[0065] It should be noted that the photovoltaic module circuit breaker that enters the unrestricted output state can transmit the electricity generated by the corresponding photovoltaic module to the inverter to achieve photovoltaic power generation output.

[0066] S102 : Each photovoltaic module circuit breaker that fails to start or is disconnected again detects the electrical parameters of its output end in real time, and determines whether the electrical parameters meet the preset starting conditions.

[0067] In actual applications, the PV module circuit breaker that fails to start or is disconnected again is still in the output restricted state, that is, the PV module circuit breaker that fails to start or is disconnected again is still in the off state, the corresponding circuit between the PV module and the inverter is disconnected, and the PV module cannot output through the inverter.

[0068] PV module disconnectors that fail to start can be individual PV module disconnectors that fail to start after initial startup. Re-disconnected PV modules typically shut down after startup when the entire PV string stops outputting power due to abnormal operating conditions such as shading or mis-plugging, causing the corresponding PV string DC bus voltage to fall below the inverter's normal value.

[0069] It should be noted that the photovoltaic module circuit breaker can obtain the electrical parameters of its output end through its own parameter acquisition unit, and then judge the obtained electrical parameters through its own processor to determine whether its real-time changing electrical parameters meet the preset start-up conditions.

[0070] If the electrical parameters meet the preset start-up conditions, step S103 is executed.

[0071] S103, the control unit restarts itself and enters the unrestricted output state.

[0072] In actual applications, after the PV module circuit breaker that fails to start or disconnects again controls itself to restart and enter the unrestricted output state, the corresponding PV module can output through the inverter.

[0073] Based on the above principles, the photovoltaic module circuit breaker provided in this embodiment can determine whether it meets the preset start-up conditions only through its own original sampling device, and restart itself after determining that it meets the preset start-up conditions. Compared with the existing start-up method, there is no need to add corresponding receiving equipment, which reduces the hardware cost of the photovoltaic module circuit breaker; and there is no need to use communication means such as PLC to achieve the start-up control of the photovoltaic module circuit breaker.

[0074] It is worth noting that an optimized startup scheme exists in the prior art that detects the changing characteristics of the DC bus voltage. While this approach can save hardware costs associated with PV module circuit breakers, it cannot be used when the PV modules are obstructed or encounter other abnormal operating conditions. The inactivated PV module circuit breakers may cause the voltage of the corresponding PV strings to fall below the inverter's startup voltage, preventing power output. Other PV strings without abnormalities will start normally and output power. In this case, the inactivated PV module circuit breakers can only be restarted by restarting the inverter, resulting in significant power loss.

[0075] The solution provided in this application does not require restarting the inverter. PV module circuit breakers that fail to start or are disconnected again can be restarted by real-time detection of whether the electrical parameters at their output terminals meet the preset starting conditions. This not only avoids the loss of power generation caused by restarting the inverter, but also improves system stability.

[0076] The inventors have discovered that when all photovoltaic module disconnects in any photovoltaic string in a photovoltaic rapid shutdown system enter the on state, that is, enter the unrestricted output state, the voltage on the DC bus in the photovoltaic rapid shutdown system is the sum of the output voltages of all photovoltaic module disconnects in the on state, and the voltage on the DC bus is divided at the output end of the photovoltaic module disconnects in the restricted output state. If the voltage on the DC bus reaches the inverter's startup voltage, the inverter will start and connect to the grid. After the inverter starts and connects to the grid, the voltage divided at the output end of the photovoltaic module disconnects in the restricted output state will maintain a certain value. If the voltage on the DC bus cannot reach the inverter's startup voltage, the voltage on the DC bus will drop below the safe voltage within a certain period of time, such as within 30 seconds, and the voltage divided at the output end of the photovoltaic module disconnects in the restricted output state will also fall below a set threshold. Therefore, according to the above characteristics, when the electrical parameter is voltage, each photovoltaic module disconnector that fails to start or disconnects again in step S102 of the present application respectively detects the electrical parameters of its output end in real time and determines whether the electrical parameters meet the preset startup conditions. This can be achieved by the specific method shown in Figure 2:

[0077] S201 , determining whether the voltage is greater than or equal to a set threshold after a preset time.

[0078] The specific value of the preset time can be determined by the specific application environment and user needs. For example, the preset time can be set to 30s, 45s, 60s, or even 1 minute or 5 minutes. This application does not limit the specific value of the preset time, as long as it meets the security requirements of the system.

[0079] Similarly, the specific value of the threshold value can also be determined according to the specific application environment and user needs. It is only necessary to ensure that the voltage of the photovoltaic module circuit breaker is greater than or equal to the set threshold and the corresponding inverter is in operation.

[0080] If the judgment result is yes, that is, it is judged that the voltage is greater than or equal to the set threshold after being between the preset values, step S202 is executed; if the judgment result is no, that is, it is judged that the voltage is not greater than or equal to the set threshold after being between the preset values, it is determined that the electrical parameters do not meet the preset starting conditions.

[0081] S202: Determine whether the electrical parameters meet the preset starting conditions.

[0082] In this embodiment, the characteristics of the output terminal voltage of each photovoltaic component circuit breaker that fails to start or is disconnected again can be utilized to determine whether the power output parameters meet the preset startup conditions by judging whether the voltage is greater than or equal to the set threshold after being within the preset range, thereby achieving the restart of each photovoltaic component circuit breaker that fails to start or is disconnected again.

[0083] In actual applications, when the inverter of the photovoltaic fast shutdown system is operating normally, its DC bus voltage is too high, and the inverter cannot perform periodic opening operations to wake up the photovoltaic module shutdown devices in the output-restricted state. In other words, it is impossible to wake up the photovoltaic module shutdown devices that failed to start up initially or are disconnected again by periodically short-circuiting the DC side of the inverter. To solve the above problem, another embodiment of the present application provides a method for determining whether the electrical parameters meet the preset startup conditions in step S102, as shown in Figure 3. The specific process is as follows:

[0084] S301: Determine whether there is a first preset disturbance in the electrical parameter.

[0085] In practical applications, the first preset disturbance is applied to any one of the voltage, current, and combined voltage and current signals on the DC side of the inverter in the photovoltaic fast shutdown system when the inverter determines that at least one photovoltaic string on its DC side is in an abnormal state after startup.

[0086] It should be noted that if a PV module in the PV rapid shutdown system is blocked, the corresponding PV module disconnector will not activate, potentially causing the output voltage of the PV string in which the PV module is located to fail to reach the inverter's startup voltage. In this case, the output current or power of the PV string will be zero. Therefore, the inverter can use sampling circuits installed on each PV string to detect whether the output current / power of each PV string connected to its DC side is zero, thereby determining whether there is an abnormal PV string.

[0087] That is, the abnormal state of the PV string is a state where the output current / power of the PV string is zero.

[0088] In actual applications, the first preset disturbance can be: a continuous disturbance within a preset duration; that is, this continuous disturbance exists until the corresponding PV module circuit breaker is successfully activated, and the above disturbance can be stopped when the inverter detects that the PV string is outputting normally. The specific value of the preset duration can be determined according to the application environment and user needs, for example, it can be tens of seconds such as 10s, 30s, or several minutes. Alternatively, the first preset disturbance can also be: a continuous disturbance that always exists or an intermittent disturbance; that is, this continuous disturbance or intermittent disturbance always exists after the corresponding PV module circuit breaker is successfully activated.

[0089] Specifically, the first preset disturbance signal may be a double frequency ripple, such as the voltage waveform shown in FIG9 . In practical applications, the first preset disturbance signal may be set to a continuous disturbance within a preset time period as shown in FIG8 , or may be set to an intermittent disturbance as shown in FIG10 , depending on the application environment and user needs.

[0090] It should be noted that the present application does not limit the specific form of the preset disturbance signal, and it is only necessary to ensure that the photovoltaic module circuit breaker can detect it.

[0091] In actual applications, the electrical parameter can be voltage, or a combined signal of voltage and current. Figures 8-10 are all shown using voltage as an example. In actual applications, it can be determined by the specific application environment and user needs, and all fall within the scope of protection of this application.

[0092] If the judgment result is yes, that is, it is judged that the electrical parameters have the first preset disturbance, step S302 is executed; if the judgment result is no, that is, it is judged that the electrical parameters do not have the first preset disturbance, it is determined that the electrical parameters meet the preset starting conditions.

[0093] S302: Determine whether the electrical parameters meet the preset starting conditions.

[0094] In this embodiment, whether the power output parameters meet the preset start-up conditions can be determined by means of a first preset disturbance, so as to avoid the problem that when the photovoltaic fast shutdown system is operating normally in the inverter, its DC bus voltage is too high and the inverter cannot perform periodic opening operations to wake up the photovoltaic component shutdown device in the output-restricted state.

[0095] Optionally, in another embodiment provided by the present application, after each photovoltaic module disconnector that fails to start or disconnects again in step S102 detects the electrical parameters of its output terminal in real time and determines whether the electrical parameters meet the preset start-up conditions, if the electrical parameters do not meet the preset start-up conditions, as shown in FIG4 , the following further comprises:

[0096] S401, the control unit continues to maintain the output restriction state.

[0097] In actual applications, when it is determined that the voltage is not greater than or equal to the set threshold after being within the preset range, or after it is determined that the electrical parameters do not have the first preset disturbance, it can be regarded as being determined that the electrical parameters do not meet the preset start-up conditions, and the photovoltaic module circuit breaker cannot control itself to start again, and will continue to maintain the restricted output state.

[0098] On the basis of the above, another embodiment of the present application further provides a photovoltaic module shutdown device, see Figure 5, which mainly includes: a switch unit (including Q1 and Q2 in the figure), a starting voltage module 200, a drive circuit 101, a processor 103, a bypass diode Dp and a parameter acquisition unit (including an input voltage acquisition unit 100, an output voltage acquisition unit 102 and a current acquisition unit 104). Among them:

[0099] The switch unit is provided on the positive branch (as shown in FIG5 ) or the negative branch (not shown) of the photovoltaic module circuit breaker, and is used to realize the opening or closing of the photovoltaic module circuit breaker according to the control of the processor 103 .

[0100] In actual applications, as shown in FIG5 , the switch unit in the photovoltaic module circuit breaker includes two connected switching transistors (Q1 and Q2), both of which are controlled by a processor 103 via a driving circuit 101. The multiple switching transistors can be connected in series and / or in parallel, depending on the specific application, and are all within the scope of protection of this application.

[0101] As shown in Figure 5, taking the number of switch tubes as 2 as an example, the input end of the switch tube Q1 serves as the input end of the switch unit and is connected to the positive input end Uin+ of the photovoltaic module circuit breaker. The output end of the switch tube Q1 is connected to the input end of the switch tube Q2, and the output end of the switch tube Q2 serves as the output end of the switch unit. The control ends of the switch tubes Q1 and Q2 serve as the control ends of the switch unit.

[0102] It should be noted that the switch tube Q1 and the switch tube Q2 are semiconductor switching devices, which can be MOSFET (Metal-Oxide-SemiconductorField-EffectTransistor), or IGBT (Insulated Gate BipolarTransistor). MOSFET is used as an example in Figure 5, and the schematic diagram with the switch tube as IGBT is not shown one by one here, and all are within the protection scope of this application.

[0103] The parameter acquisition module includes at least one of the output voltage acquisition unit 102 and the current acquisition unit 104 , and may also include an input voltage acquisition unit 100 , which is at least used to acquire electrical parameters at the output end of the photovoltaic module circuit breaker and output the electrical parameters to the processor 103 .

[0104] In actual applications, the parameter acquisition module can not only collect the output current and output voltage of the photovoltaic module circuit breaker, but also collect the input voltage of the photovoltaic module circuit breaker, which can be determined according to the specific application environment. This application does not limit the data that can be collected by the parameter acquisition module, and all of them fall within the scope of protection of this application.

[0105] The starting voltage module 200 is used to output a starting voltage to the output end of the photovoltaic module circuit breaker under the control of the processor 103 when the photovoltaic module circuit breaker is turned off and in a normal state, so that the inverter can detect the DC bus voltage to know the maximum number of photovoltaic module circuit breakers in a normal state in the corresponding string.

[0106] In practical applications, the positive and negative output terminals of the starting voltage module 200 are connected to the positive and negative output terminals of the photovoltaic module circuit breaker, respectively.

[0107] It should be noted that the starting voltage module 200 has a certain internal resistance, and its output can be short-circuited. Therefore, when the starting voltage module 200 is short-circuited, its output voltage is 0.

[0108] The bypass diode Dp is used to bypass the PV module circuit breaker when it is turned off. The anode of the bypass diode Dp is connected to the negative output terminal Uout- of the PV module circuit breaker, and the cathode is connected to the positive output terminal Uout+ of the PV module circuit breaker.

[0109] The output terminal of the processor 103 is connected to the control terminal of the switch unit through the drive circuit 101, and is used to execute the startup method of the photovoltaic fast shutdown system as described in any of the above embodiments.

[0110] It should be noted that the specific execution process and working principle of the photovoltaic module shutdown device for the corresponding steps in the startup method of the photovoltaic rapid shutdown system are detailed in the corresponding parts of the startup method of the photovoltaic rapid shutdown system provided in the above embodiment, and will not be repeated here.

[0111] In this embodiment, the photovoltaic module circuit breaker can realize its own opening and closing by collecting electrical parameters through its own parameter collection unit, without using communication signals or setting up an additional signal receiving module to receive the opening / closing communication signal output by the inverter, thereby reducing the hardware cost of the photovoltaic module circuit breaker.

[0112] On the basis of the above, another embodiment of the present application further provides an inverter, as shown in FIG6 , which mainly includes: a sampling circuit 203, an inverter circuit 205, a signal conditioning circuit 206 and a controller 207. Among them:

[0113] The sampling circuit 203 is provided on the DC side of the inverter and is used to sample the voltage on the DC side of the inverter and the output current / power of each photovoltaic string connected in parallel thereto.

[0114] The output end of the sampling circuit 203 is connected to the input end of the controller 207 through the signal conditioning circuit 206 .

[0115] The controller 207 is used to control the operation of the inverter circuit 205 to achieve grid-connected power generation and / or apply corresponding disturbances to its DC side so that each photovoltaic component disconnector in each photovoltaic string can execute the startup method of the photovoltaic fast shutdown system as described in any of the above embodiments.

[0116] In practical applications, the controller 207 can be used to control the inverter circuit 205 to perform periodic opening operations to generate the second preset disturbance, and can also be used to control the operation of the inverter circuit 205 to apply the first preset disturbance to its DC side. Of course, this is not limited to the above, and the specific type of disturbance to be applied can also be determined by the user according to the specific application environment and user needs, all of which fall within the scope of protection of this application.

[0117] It should be noted that the specific execution process and working principle of the inverter are detailed in the corresponding part of the startup method of the photovoltaic fast shutdown system provided in the above embodiment, and will not be repeated here.

[0118] In actual applications, as also shown in FIG6 , the inverter further includes: a Boost circuit 204 provided before the inverter circuit 205 ; the input end of the Boost circuit 204 serves as the DC side of the inverter.

[0119] It should be noted that the Boost circuit 204 can be a flying capacitor type three-level boost circuit, and of course it can also be other existing structures. This application does not limit the specific type of the Boost circuit 204, and all types fall within the scope of protection of this application.

[0120] In this embodiment, the inverter controls the inverter circuit 205 through the controller 207 to perform periodic opening operation to generate the second preset disturbance, which can realize the first startup of each photovoltaic module circuit breaker connected to the DC side of the inverter, and the controller 207 controls the inverter circuit 205 to generate the first preset disturbance, which can realize the restart of the photovoltaic module circuit breaker that fails to start or is disconnected again; compared with the existing method of controlling the opening or closing of the photovoltaic module circuit breaker by setting a start signal sending unit, the present application does not require additional equipment on the DC bus, and does not require a larger DC combiner box or the configuration of an additional DC combiner box to cooperate with the installation during the installation process, thereby reducing construction costs; and there is no need to use communication means such as PLC to achieve startup control of the photovoltaic module circuit breaker.

[0121] On the basis of the above, another embodiment of the present application further provides a photovoltaic fast shutdown system, as shown in Figure 7, which mainly includes: an inverter 301 as described in any of the above embodiments, and a plurality of photovoltaic strings 302 connected in parallel on its DC side.

[0122] The photovoltaic string 302 includes multiple photovoltaic component disconnectors 202 as described in any of the above embodiments. The output ends of each photovoltaic component disconnector 202 are connected in series to form the two ends of the photovoltaic string 302, and the input ends of each photovoltaic component disconnector 202 are respectively connected to corresponding photovoltaic components 201.

[0123] In practical applications, in each photovoltaic string 302 of the photovoltaic rapid shutdown system, each photovoltaic module 201 is connected in series through a corresponding photovoltaic module disconnector 202 , and the voltage across both ends of the series connection is the voltage of the DC bus.

[0124] It should be noted that the number of photovoltaic modules 201 connected to the input end of each photovoltaic module circuit breaker 202 is generally one; of course, it is not limited to this. Depending on the specific application environment and user needs, multiple photovoltaic modules can be set to share one photovoltaic module circuit breaker, for example, two photovoltaic modules can be set to share the same photovoltaic module circuit breaker.

[0125] It should also be noted that the specific execution process and working principle of the photovoltaic rapid shutdown system are detailed in the starting method of the photovoltaic rapid shutdown system, the photovoltaic module shutdown device and the corresponding parts of the inverter provided in the above embodiments, which will not be repeated here.

[0126] In this embodiment, the combined control of PV module disconnector 202 and inverter 301 activates the photovoltaic rapid shutdown system, making it highly applicable to industries that provide both PV module disconnector 202 and inverter 301. Furthermore, the hardware cost of both PV module disconnector 202 and inverter 301 in this photovoltaic rapid shutdown system is relatively low, resulting in a correspondingly low hardware cost for the photovoltaic rapid shutdown system.

[0127] Each embodiment in this specification is described in a progressive manner. The same or similar parts between the embodiments can be referred to each other. Each embodiment focuses on the differences from other embodiments. In particular, for system or system embodiments, since they are basically similar to method embodiments, the description is relatively simple. For relevant parts, refer to the partial description of the method embodiment. The system and system embodiments described above are merely schematic, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment. A person of ordinary skill in the art can understand and implement it without expending creative work.

[0128] Professionals may further appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the above description has generally described the components and steps of each example according to their functions. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians may use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0129] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present application. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

[0130] It should also be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article, or device comprising the element.

Claims

DEPCT6727 / 09 / 25661. Method for initiating a fast shutdown system, where more than one photovoltaic line is connected in parallel on the DC side of the inverter in the fast shutdown system, and the method of combination: after each shutdown device in the fast shutdown system is initially initiated, the shutdown device is switched to the unlimited output mode in response to the successful initial startup of the shutdown device; and the electrical parameters at the output terminals of the shutdown device are sampled in real time, determining whether the electrical parameters meet the preset initial conditions, the shutdown device is switched on and the shutdown device is operated in the unlimited output mode in response to the result of determining that the electrical parameters meet the preset initial conditions, by the shutdown device in response to the failure of the shutdown device during startup or when the shutdown device is switched off.

2. Method for initiating a fast shutdown system according to claim 1, where the electrical parameters include voltage,And the determination of whether the electrical parameters meet the preset initial conditions includes: determining whether the voltage is greater than or equal to the threshold after a preset time period has elapsed; and determining, in response to the determination that the voltage is greater than or equal to the threshold after a preset time period has elapsed, that the electrical parameters meet the preset initial conditions.

3. The method for initiating a fast shutdown system according to claim 1, where the determination of whether the electrical parameters meet the preset initial conditions includes: detecting a preset interference in one of the electrical parameters; and determining, in response to the preset interference detected in one of the electrical parameters, that the electrical parameters meet the preset initial conditions.

4. The method for initiating a fast shutdown system according to claim 3, where the electrical parameters consist of voltage; or the electrical parameters consist of both voltage and current.

5. The method for initiating a fast shutdown system according to claim 3,Where the first preset disturbance is applied to the DC-side voltage of the inverter in a fast shutdown system when it is determined that at least one of the more than one photovoltaic lines on the DC-side of the inverter is under an abnormal condition after the inverter is started; the first preset disturbance is applied to the DC-side current of the inverter in a fast shutdown system when it is determined that at least one of the more than one photovoltaic lines on the DC-side of the inverter is under an abnormal condition after the inverter is started; or the first preset disturbance is applied to both the voltage and current on the DC-side of the inverter in a fast shutdown system when it is determined that at least one of the more than one photovoltaic lines on the DC-side of the inverter is under an abnormal condition after the inverter is started.

6. Method for initiating the fast shutdown system according to claim 5.

7. Method for initiating the fast shutdown system under claim 3, where the first preset disturbance is a continuous disturbance that persists for a preset period; or the first preset disturbance is a continuous or discontinuous disturbance that is present at all times.

8. Method for initiating the fast shutdown system under claim 7, where the first preset disturbance is a pair frequency ripple.

9. Method for initiating the fast shutdown system under any one of claims 1 through 8, which is further combined with: operating the shutdown device in a limited output mode in response to the determination result that the electrical parameters do not meet the preset initial conditions after determining whether the electrical parameters meet the preset initial conditions.

10. Method for initiating the fast shutdown system under any one of claims 1 through 8,Where the initial shutdown is initiated by: opening the shutdown device and operating the shutdown device in the unlimited output mode by the shutdown device when a second preset disturbance is detected in the electrical parameters at the output terminals of the shutdown device.

11. Method for rapid shutdown initiation according to claim 10, where the second preset disturbance is a preset interval pulse.

12. The shutdown device for the photovoltaic module, consisting of: a switching unit; an initial voltage module; a driver circuit; a processor; a bypass diode; and a parameter sampling unit, where the switching unit is provided between the positive input and positive output terminals of the shutdown device or between the negative input and negative output terminals of the shutdown device.and is configured to open or close the shutdown device under the control of the processor; the parameter sampling unit is configured to sample electrical parameters at the output terminals of the shutdown device and output the sampled electrical parameters to the processor; the startup voltage module is configured to output, under the control of the processor, the startup voltage to the output terminals of the shutdown device when the shutdown device is closed and under normal conditions; a bypass diode is configured to provide a current path that bypasses the shutdown device when the shutdown device is closed; and the output terminals of the processor are connected to the control terminals of the switching unit by a driver circuit, and the processor is configured to implement a fast shutdown startup method according to one of claims 1 through 11.

13. Shutdown device for the photovoltaic module according to claim 12, where the switching unit consists of two transistor switches connected in series, and the two transistor switches are controlled by the processor by a driver circuit.

14. Inverter,It consists of: a sampling circuit; an inverter circuit; a signal processing circuit; and a controller. The sampling circuit is provided on the DC side of the inverter and is configured to sample the voltage on the DC side of the inverter and obtain the current or power output from each parallel-connected photovoltaic wire. The parallel-connected photovoltaic wires are connected to the DC side of the inverter; the output terminal of the sampling circuit is connected to the input terminal of the controller via the signal processing circuit. At; and the controller is configured to control the inverter circuit to be connected to the grid and / or to apply interference to the DC side of the inverter, for each shutdown device in the photovoltaic line to implement the method for initiating the fast shutdown system according to one of the claims 1 through 11.

15. Inverter according to claim 14, which includes additionally: a boost circuit provided at the forward distance of the inverter circuit, where the input terminals of the boost circuit act as the DC side of the inverter.

16. Fast shutdown system,It comprises an inverter according to claims 14 to 15; and more than one photovoltaic wire connected in parallel on the DC side of the inverter, where each more than one photovoltaic wire comprises more than one shutdown device according to claims 12 or 13, the output terminals of the shutdown devices are connected in series to form two terminals of the photovoltaic wire, and the input terminals of the shutdown devices are connected to the corresponding photovoltaic module;

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