Photovoltaic power generation system, fast shutdown method, and photovoltaic power generation inverter

Abstract

The present application discloses a photovoltaic power generation system, a fast shutdown method, and a photovoltaic power generation inverter. The system includes an inverter, a fan, and a controller. A photovoltaic power generation string and a DC bus capacitor are connected between a positive input terminal and a negative input terminal of the inverter. The controller receives a fast shutdown command and sends a drive signal to a switching transistor in the inverter, so that the switching transistor performs a switching operation under the action of the drive signal, and the switching transistor consumes electric energy during the switching operation. Or the controller turns on the fan after receiving the fast shutdown command, so as to consume electric energy by using the fan. Or the controller can also send a drive signal to the switching transistor to control the fan to be turned on, so that both the switching transistor and the fan consume electric energy. In the photovoltaic power generation system provided in the embodiment of the present application, the discharge speed of the DC bus capacitor is increased so as to accelerate the drop of the DC bus voltage without adding additional hardware circuits, thereby ensuring that the electricity stored in the DC bus capacitor is timely released during the fast shutdown of the photovoltaic power generation system, and meeting the standard requirements for fast shutdown.

Description

[Technical Field]

[0001] This application relates to the field of photovoltaic technology, and more particularly to photovoltaic systems, fast shutdown methods, and photovoltaic inverters. [Background technology]

[0002] In a solar power generation system, an IA case sometimes occurs in which the solar power generation system needs to be shut down quickly. To ensure safety, when a fast shutdown is triggered, both the voltage across any DC input conductor of the inverter in the solar power generation system and the voltage of any DC input conductor of the inverter with respect to ground must be reduced to 30 V or less within 30 seconds.

[0003] Currently, when a photovoltaic power generation system undergoes a fast shutdown, the inverter performs shutdown protection after receiving a fast shutdown command, and discharge between the inverter's DC input conductors and discharge of any DC input conductor of the inverter to ground is performed by using the conductor's respective resistor. However, self-discharge of the DC input conductors performed by using internal resistors may not meet the above-mentioned fast shutdown criteria.

[0004] Currently, to ensure that the voltage across any DC input conductor of the inverter and the voltage of any DC input conductor of the inverter with respect to ground are reduced to 30 V or less within 30 seconds during fast shutdown, an energy absorption circuit can be additionally connected in parallel to the DC bus at the input end of the inverter by using a switching transistor. After receiving a fast shutdown command, the inverter controls the switching transistor to be turned on, thereby discharging through the energy absorption circuit. Although this solution can ensure that the discharge speed of the inverter meets the aforementioned safety standards, it adds additional hardware circuits (including the energy absorption circuit and the switching transistor), which increases the cost of the inverter. Furthermore, the added switching transistor introduces a risk of malfunction. Summary of the Invention

[0005] The present application provides a solar power generation system, a fast shutdown method, and a solar power generation inverter, so that when the solar power generation system needs to be shut down quickly, the voltage on the DC side can be reduced to a specified voltage or below within the time required by the standard.

[0006] One embodiment of the present application provides a solar power generation system including an inverter, a fan, and a controller. A solar power generation string and a DC bus capacitor are connected between a positive input and a negative input of the inverter. The inverter is configured to convert DC electricity provided by the solar power generation string into AC electricity and send the AC electricity to an AC power grid or a load. The controller is configured to receive a fast shutdown command and reduce the voltage on the DC bus capacitor in at least one manner. The at least one manner includes sending a drive signal by the controller to a switching transistor in the inverter so that the switching transistor performs a switching operation under the operation of the drive signal to consume electrical energy, or turning on the fan by the controller to consume electrical energy.

[0007] According to the solution provided in the present application, after receiving a fast shutdown command, the controller sends a drive signal to the switching transistor in the inverter, so that the switching transistor performs a switching operation under the action of the drive signal, and the switching transistor consumes electrical energy during the switching operation. Alternatively, after receiving a fast shutdown command, the controller turns on the fan and consumes electrical energy by using the fan, or the controller sends a drive signal to the switching transistor and also controls the fan to be turned on, so that both the switching transistor and the fan consume electrical energy. In the solar power generation system provided in this embodiment of the present application, the discharge speed of the DC bus capacitor is increased without adding any additional hardware circuit, so that the decrease of the DC bus voltage is accelerated, thereby ensuring that the electricity stored in the DC bus capacitor is released in a timely manner during the fast shutdown of the solar power generation system to meet the standard requirements for fast shutdown.

[0008] In one possible implementation, the drive signal is generated by using a modulating wave and a carrier wave, and the controller is configured to change the frequency of the carrier wave to change the frequency of the drive signal and send the changed drive signal to the switching transistor, thereby increasing the electrical energy consumed by the switching transistor. According to the solution in this embodiment of the present invention, the period of the drive signal is changed by adjusting the period of the carrier wave to adjust the power consumed by the switching transistor. As a result, the switching transistor consumes the power stored in the DC bus capacitor within a predetermined time, thereby ensuring that the electricity stored in the DC bus capacitor is released in a timely manner during fast shutdown of the photovoltaic power generation system, meeting the standard requirements for fast shutdown.

[0009] In one possible implementation, the drive signal is generated by using the modulation wave and the carrier wave, and the controller is configured to change the frequency of the modulation wave to change the drive signal and send the changed drive signal to the switching transistor, thereby increasing the electrical energy consumed by the switching transistor. According to the solution in this embodiment of the present invention, the frequency of the drive signal is also changed by adjusting the period of the carrier wave to adjust the power consumed by the switching transistor. As a result, the switching transistor consumes the power stored in the DC bus capacitor within a predetermined time, thereby ensuring that the electricity stored in the DC bus capacitor is released in a timely manner during fast shutdown of the photovoltaic power generation system, meeting the standard requirements for fast shutdown.

[0010] In one possible implementation, the solar power generation system provided in this embodiment of the present application further includes an optimizer. The input terminal of the inverter is connected to multiple solar power generation strings connected in parallel with each other. Each solar power generation string includes multiple solar power generation modules and multiple optimizers. The multiple solar power generation modules have a one-to-one correspondence with the multiple optimizers. The output terminal of each solar power generation module is connected to the input terminal of the corresponding optimizer. The output terminals of all optimizers in one solar power generation string are connected in series with each other and connected to the input terminal of the inverter. The optimizer is configured to receive the fast shutdown command, stop operating, and disconnect from the solar power generation module. In addition to a voltage boost function, the optimizer in this embodiment of the present application may also have a maximum power point tracking function. Since the optimizer tracks a corresponding solar power generation module, the optimizer may perform MPPT for the solar power generation module corresponding to the optimizer, thereby improving the solar power generation electrical energy conversion efficiency.

[0011] In one possible implementation, the solar power generation system provided in this embodiment of the present application further includes a filter circuit. The inverter includes a power conversion circuit and the filter circuit. The input terminal of the power conversion circuit is connected to the solar power generation string. The filter circuit is connected to the output terminal of the power conversion circuit. When the controller sends the drive signal to the switching transistor in the inverter, the DC bus capacitor, the switching transistor, and the filter circuit form a path such that the filter circuit consumes electrical energy to reduce the voltage on the DC bus capacitor. A higher frequency of the drive signal indicates more electricity consumed by an inductor in the filter circuit. If the solar power generation system provided in this embodiment of the present application includes a filter circuit, the switching transistor and the filter circuit can form a path when the switching transistor operates, resulting in electrical energy being consumed by using impedance in the filter circuit, thereby further accelerating the reduction of the DC bus voltage.

[0012] In one possible implementation, the photovoltaic power generation system provided in this embodiment of the present application further includes a grid connection circuit breaker connected between an output of the inverter and the AC power grid, and the controller is further configured to control the grid connection circuit breaker to disconnect the inverter from the AC power grid after receiving the fast shutdown command.

[0013] In one possible implementation, the solar power generation system provided in this embodiment of the present application further comprises a host computer, which is configured to send the fast shutdown command to the controller and the optimizer.

[0014] In one possible implementation, the frequency of the drive signal is a non-fundamental frequency.

[0015] In one possible implementation, the inverter is a three-level T-type inverter.

[0016] In one possible implementation, the controller is integrated into the cabinet of the inverter and the fan is integrated into the cabinet of the inverter.

[0017] In one possible implementation, the inverter is a string inverter or a central inverter.

[0018] In accordance with the solar power generation system provided above, one embodiment of this application further provides a fast shutdown method for a solar power generation system. The solar power generation system includes an inverter and a fan. The inverter includes a switching transistor. A solar power generation string and a DC bus capacitor are connected between a positive input terminal and a negative input terminal of the inverter. The inverter is configured to convert DC electricity provided by the solar power generation string into AC electricity and send the AC electricity to an AC power grid or a load. The method includes receiving a fast shutdown command and reducing a voltage on the DC bus capacitor in at least one manner. The at least one manner is sending a drive signal to a switching transistor in the inverter so that the switching transistor performs a switching operation under the operation of the drive signal to consume electrical energy, or turning on the fan so that the fan consumes electrical energy.

[0019] In one possible implementation, the drive signal is generated by using a modulating wave and a carrier wave, and transmitting the drive signal to the switching transistor in the inverter includes, among other things, changing the frequency of the carrier wave to change the frequency of the drive signal, and transmitting the changed drive signal to the switching transistor, thereby increasing the electrical energy consumed by the switching transistor and the filter circuit.

[0020] In one possible implementation, the drive signal is generated by using the modulating wave and the carrier wave, and transmitting the drive signal to the switching transistor in the inverter includes, among other things, changing the frequency of the modulating wave to modify the drive signal and transmitting the modified drive signal to the switching transistor, thereby increasing the electrical energy consumed by the switching transistor and the filter circuit.

[0021] In one possible implementation, the photovoltaic power generation system further includes a filter circuit, the filter circuit connected to an output of the inverter, and the method further includes controlling the DC bus capacitor, the switching transistor, and the filter circuit to form a path such that the filter circuit consumes electrical energy to reduce the voltage on the DC bus capacitor, where a higher frequency of the drive signal indicates more electricity consumed by an inductor in the filter circuit.

[0022] In accordance with the solar power generation system and the fast shutdown method for a solar power generation system provided in the above embodiments, one embodiment of the present application further provides a solar power inverter including a power conversion circuit, a fan, and an inverter controller. The power conversion circuit includes a switching transistor. A solar power generation string and a DC bus capacitor are connected between a positive input terminal and a negative input terminal of the power conversion circuit. The inverter controller is configured to receive a fast shutdown command and reduce the voltage on the DC bus capacitor in at least one manner. Here, the at least one manner includes sending a drive signal to the switching transistor by the inverter controller so that the switching transistor performs a switching operation under the operation of the drive signal to consume electrical energy, or turning on the fan by the inverter controller to consume electrical energy.

[0023] In one possible implementation, the drive signal is generated by using a modulating wave and a carrier wave, and the inverter controller is configured to, in particular, change the frequency of the carrier wave to change the frequency of the drive signal and send the changed drive signal to the switching transistor, thereby increasing the electrical energy consumed by the switching transistor.

[0024] In one possible implementation, the drive signal is generated by using the modulating wave and the carrier wave, and the inverter controller is configured to, in particular, change the frequency of the modulating wave to modify the drive signal and send the modified drive signal to the switching transistor, thereby increasing the electrical energy consumed by the switching transistor.

[0025] In one possible implementation, the photovoltaic inverter further includes a filter circuit. The input of the power conversion circuit is connected to the photovoltaic string. The filter circuit is connected to the output of the power conversion circuit. When the inverter controller sends the drive signal to the switching transistor, the DC bus capacitor, the switching transistor, and the filter circuit form a path such that the filter circuit consumes electrical energy to reduce the voltage on the DC bus capacitor. A higher frequency of the drive signal indicates more electricity consumed by an inductor in the filter circuit.

[0026] From the above technical solutions, it can be seen that the embodiments of the present application have the following advantages:

[0027] The photovoltaic power generation system provided in the embodiment of the present application includes an inverter, a fan, and a controller. A photovoltaic power generation string and a DC bus capacitor are connected between the positive input terminal and the negative input terminal of the inverter. After receiving a fast shutdown command, the controller sends a drive signal to a switching transistor in the inverter, so that the switching transistor performs a switching operation under the action of the drive signal, and the switching transistor consumes electrical energy during the switching operation. Alternatively, after receiving the fast shutdown command, the controller turns on the fan to consume electrical energy by using the fan, or the controller also sends a drive signal to the switching transistor to control the fan to be turned on, so that both the switching transistor and the fan consume electrical energy, thereby accelerating the discharge of the DC bus capacitor and increasing the DC side of the inverter, i.e., inputIn the solar power generation system provided in this embodiment of the present application, the discharge speed of the DC bus capacitor is increased so as to accelerate the drop of the DC bus voltage without adding any additional hardware circuit, thereby ensuring that the electricity stored in the DC bus capacitor is released in a timely manner during the fast shutdown of the solar power generation system to meet the standard requirement of fast shutdown, i.e., to reduce the voltage on the DC side of the inverter to 30V or less within 30 seconds. [Brief explanation of the drawings]

[0028] [Figure 1] FIG. 1 is a schematic diagram of a structure of a solar power generation system according to one embodiment of the present invention. [Figure 2] FIG. 2 is a schematic diagram of an inverter structure according to one embodiment of the present invention. [Figure 3] FIG. 3 is a schematic diagram of another solar power generation system structure according to one embodiment of the present invention. [Figure 4] FIG. 4 is a schematic diagram of the structure of a DC / AC circuit in an inverter according to one embodiment of the present invention. [Figure 5] FIG. 5 is a diagram illustrating the operating principle of a fan according to one embodiment of the present invention. [Figure 6] FIG. 6 is a schematic diagram of yet another structure of a solar power generation system according to an embodiment of the present invention. [Figure 7] FIG. 7 is a flowchart of a fast shutdown method for a solar power generation system according to an embodiment of the present application. [Figure 8] FIG. 8 is a schematic diagram of a structure of a photovoltaic inverter according to one embodiment of the present application. DETAILED DESCRIPTION OF THE INVENTION

[0029] In the following description, the terms "first" and "second" are used for descriptive purposes only and should not be understood as an indication or implication of the relative importance or quantity of the technical features shown. Thus, a feature modified by "first," "second," etc. may explicitly or implicitly include one or more features. In the description of this application, unless otherwise specified, "a plurality of" means two or more.

[0030] Additionally, in this application, directional terms such as "above" and "below" may include, but are not limited to, definitions relative to the orientation of components generally disposed in the accompanying drawings. It should be understood that these directional terms are relative concepts and are used for relative description and clarity, and may correspondingly change based on changes in the orientation of the components disposed in the accompanying drawings.

[0031] In this application, unless otherwise specified and limited, the term "connection" should be understood in a broad sense. For example, "connection" may be a fixed connection, a detachable connection, or an integral connection, and may be a direct connection or an indirect connection implemented through an intermediate medium. In addition, the term "coupling" may refer to a manner of electrical connection for signal transmission. "Coupling" may be a direct electrical connection or an indirect electrical connection through an intermediate medium.

[0032] To help those skilled in the art better understand the technical solutions provided in the embodiments of the present application, the following first describes the architecture of a solar power generation system.

[0033] FIG. 1 is a schematic diagram of a structure of a solar power generation system according to one embodiment of the present invention.

[0034] The solar power generation system in this embodiment of the present application may include one solar power generation string, or may include multiple solar power generation strings. For the solar power generation system in Figure 1, an example of only two solar power generation strings is used, which is not limited in this embodiment of the present application.

[0035] 1 , the solar power generation system in this embodiment of the present application includes an inverter 100, a first solar power generation string 300, and a second solar power generation string 400. The inverter 100 may include a DC bus capacitor 101 and a power conversion circuit 102. In other words, the DC bus capacitor 101 may be integrated into the cabinet of the inverter 100. Alternatively, the DC bus capacitor 101 may be located outside the cabinet of the inverter 100.

[0036] Each of the first solar power generation string 300 and the second solar power generation string 400 is connected to an input terminal of the inverter 100. The output side of the inverter 100 is configured to be connected to an AC power grid 200. In this embodiment, an example will be described in which the inverter 100 is a three-phase inverter. It should be understood that the solar power generation system provided in this embodiment of the present application may be a three-phase solar power generation system or a single-phase solar power generation system for home use, which is not particularly limited in this embodiment of the present application.

[0037] The positive input of inverter 100 is connected to the positive DC bus, and the negative input of inverter 100 is connected to the negative DC bus. Because DC bus capacitor 101 is connected between the positive DC bus and the negative DC bus, during fast shutdown of the solar power generation system, a relatively high voltage still accumulates at the input of inverter 100, i.e., DC bus capacitor 101. Therefore, an effective solution is needed to quickly discharge DC bus capacitor 101 during fast shutdown so as to reduce the voltage at the DC side, i.e., input of inverter 100, to below 30 V within 30 seconds.

[0038] Currently, in order to quickly release the voltage on the DC bus capacitor during fast shutdown, an energy absorption circuit can be additionally connected to the DC bus at the input end of the inverter by using a switching transistor. After receiving a fast shutdown command, the inverter controls the switching transistor to be turned on, so that the voltage on the DC bus is released through the energy absorption circuit. However, this method requires additional hardware circuitry to be added to the DC bus, which results in an increase in the cost of the solar power generation system. Furthermore, malfunction of the switching transistor may occur, resulting in unnecessary losses.

[0039] The embodiments of the present application provide a solar power generation system, so that the voltage at the input end of the inverter can be quickly reduced during fast shutdown without requiring additional hardware circuits. After receiving a fast shutdown command, the controller can use a switching transistor in the inverter to consume the electrical energy stored in the DC bus capacitor, and can also use a fan to consume the electrical energy stored in the DC bus capacitor. According to the technical solutions provided in the embodiments of the present application, the voltage at the input end of the inverter can be quickly reduced, and no additional hardware circuits need to be added. Therefore, the cost of the solar power generation system can be reduced.

[0040] To help those skilled in the art better understand the solar power generation system provided in the embodiments of the present application, the following will specifically describe the structure of the inverter in the solar power generation system provided in the embodiments of the present application.

[0041] The inverter in the solar power generation system provided in the embodiment of the present application may be a string inverter or a central inverter. The string inverter includes two levels of circuits, where the first level circuit is a DC / DC (straight current / direct current) circuit, and the second level circuit is DC / AC (straight The central inverter includes only one level of DC / AC circuit. In the following, the string inverter of FIG. 2 is used as an example to describe the inverter provided in the embodiment of the present application.

[0042] FIG. 2 is a schematic diagram of an inverter structure according to one embodiment of the present invention.

[0043] In this embodiment, for the purpose of explanation, an example in which the DC bus capacitor 101 is incorporated into the inverter is used. As shown in Figure 2, the inverter in this embodiment of the present application includes the DC bus capacitor 101 and the power conversion circuit 102.

[0044] In this embodiment of the present application, an example in which the DC bus capacitor 101 includes a first capacitor C1 and a second capacitor C2 connected in series is used for illustration purposes. It should be noted that in this embodiment of the present application, the structure of the DC bus capacitor 101 is described by using the first capacitor C1 and the second capacitor C2 only as an example. In practical applications, the DC bus capacitor may include one capacitor or may include more capacitors, which is not limited in this embodiment of the present application.

[0045] The input of the power conversion circuit 102 in this embodiment of the present application is connected to a DC bus capacitor 101. If the DC bus capacitor 101 includes multiple capacitors, a first capacitor C1 and a second capacitor C2 in the series-connected DC bus capacitor 101 are connected between the positive input of the power conversion circuit 102 and the negative input of the power conversion circuit 102, as shown in Figure 2. If the DC bus capacitor 101 includes only one capacitor, the DC bus capacitor 101 is connected between the positive input of the power conversion circuit 102 and the negative input of the power conversion circuit 102.

[0046] The power conversion circuit 102 includes a DC / DC circuit 1021, a DC / AC circuit 1022, a third capacitor C3, and a fourth capacitor C4. The third capacitor C3 and the fourth capacitor C4 connected in series are connected between the positive output terminal and the negative output terminal of the DC / DC circuit 1021. The positive input terminal and the negative input terminal of the DC / AC circuit 1022 are connected to the positive output terminal and the negative output terminal of the DC / DC circuit 1021, respectively. The DC / DC circuit 1021 provided in this embodiment of the present application is configured to boost or buck direct current electricity at the input terminal of the DC / DC circuit 1021, and then output the processed direct current electricity to the DC / AC circuit 1022. It should be understood that the DC / AC circuit 1022 provided in this embodiment of the present application is configured to convert the direct current electricity output by the DC / DC circuit 1021 into alternating current electricity and provide the alternating current electricity to an AC power grid or an AC load.

[0047] It should be understood that during fast shutdown of the photovoltaic power generation system, in the solution provided in this embodiment of the present application, the DC voltage at the input end of the inverter is reduced mainly by releasing the electrical energy stored in the first capacitor C1 and the second capacitor C2.

[0048] Hereinafter, a solar power generation system provided in an embodiment of the present application will be specifically described with reference to the accompanying drawings.

[0049] System Embodiment The photovoltaic power generation system provided in an embodiment of the present application includes an inverter, a fan, and a controller. A photovoltaic power generation string and a DC bus capacitor are connected between a positive input terminal and a negative input terminal of the inverter. After receiving a fast shutdown command, the controller sends a drive signal to a switching transistor in the inverter, so that the switching transistor performs a switching operation under the action of the drive signal, and the switching transistor consumes electrical energy during the switching operation. Alternatively, after receiving the fast shutdown command, the controller may turn on the fan and consume electrical energy by using the fan, or the controller may send a drive signal to the switching transistor and also control the fan to be turned on, so that both the switching transistor and the fan consume electrical energy, thereby accelerating the discharge of the DC bus capacitor and reducing the DC bus voltage as quickly as possible. In the solar power generation system provided in the embodiment of the present application, the discharge rate of the DC bus capacitor is increased so as to accelerate the drop in the DC bus voltage without adding any additional hardware circuit, thereby allowing the electricity stored in the DC bus capacitor to be released in a timely manner during the fast shutdown of the solar power generation system, meeting the standard requirements for fast shutdown, i.e., the voltage on the DC side of the inverter is reduced to 30V or less within 30 seconds.

[0050] When the solar power generation system provided in the embodiment of the present application includes a fan, the fan provided in the embodiment may be integrated into the inverter cabinet and dissipate heat for the inverter when the inverter operates normally, or the fan in the embodiment of the present application may exist independently of the inverter. This is not limited in the embodiment of the present application. The controller in the embodiment of the present application may be integrated into the inverter cabinet or may exist independently as a separate device. This is not limited in the embodiment of the present application. The solar power generation system provided in the embodiment of the present application may or may not include a filter circuit. This is not limited in the embodiment of the present application. When the solar power generation system provided in the embodiment of the present application includes a filter circuit, the filter circuit may function as an independent device connected to the output end of the inverter or may be integrated into the inverter. This is not limited in the embodiment of the present application. In the following, FIG. 3 is used as an example to describe the solar power generation system provided in one embodiment of the present application.

[0051] FIG. 3 is a schematic diagram of another solar power generation system structure according to one embodiment of the present invention.

[0052] The solar power generation system provided in this embodiment of the present application includes an inverter 100 , a fan 500 , a filter circuit 600 , and a controller 700 .

[0053] A photovoltaic power generation string and a DC bus capacitor are connected between a positive input and a negative input of inverter 100. Inverter 100 is configured to convert DC electricity provided by the photovoltaic power generation string into AC electricity and deliver the AC electricity to an AC power grid or a load. For example, inverter 100 may be a three-level T-type inverter.

[0054] The controller 700 is configured to receive the fast shutdown command and reduce the voltage on the DC bus capacitor in at least one of the following manners, where the at least one manner includes: the controller 700 sends a drive signal to a switching transistor in the inverter 100, so that the switching transistor performs a switching operation under the action of the drive signal and consumes electrical energy, or the controller 700 turns on the fan 500 and consumes electrical energy.

[0055] It should be understood that the controller 700 is connected to each of the inverter 100 and the fan 500. In a possible implementation, when the solar power generation system in this embodiment of the present application includes the filter circuit 600, the inverter 100 The output terminal of the inverter is connected to the filter circuit 600. When the switching transistor in this embodiment of the present application performs a switching operation under the action of the driving signal to consume electrical energy, the inverter 100 The current on the filter circuit 600 connected to the output of the filter circuit 600 also varies accordingly. In this case, the filter circuit 600 also consumes some electrical energy.

[0056] It should be noted that in this embodiment of the present application, the frequency of the drive signal may be a non-fundamental frequency. For example, the drive signal sent by the controller to the inverter may be a pulse width modulation (PWM) signal.

[0057] It can be seen that during the fast shutdown of the photovoltaic power generation system provided in this embodiment of the present application, the controller sends a driving signal to the switching transistor to control the switching transistor to perform a switching operation, and the switching transistor consumes electrical energy when performing the operation, where a higher switching frequency of the switching transistor indicates a larger electrical energy consumption, or the controller controls the fan to be turned on, so that the fan quickly consumes electrical energy. In the solution provided in this embodiment of the present application, alternatively, the controller can drive the switching transistor and simultaneously turn on the fan to consume electrical energy, thereby accelerating the electrical energy discharge of the output bus capacitor, so as to reduce the DC side, i.e., the inverter's input Therefore, according to the solution provided in this embodiment of the present application, the discharge rate of the DC bus capacitor is increased without adding an additional energy absorption circuit, thereby accelerating the reduction of the DC bus voltage. This ensures that the inverter releases the electricity stored in the DC bus capacitor in a timely manner during fast shutdown, so that the discharge rate of the inverter provided in this embodiment of the present application reaches the specified safety standard during fast shutdown. Here, the standard is that the voltage on the DC side, i.e., the input end of the inverter, is reduced to 30V or less within 30 seconds.

[0058] In the solar power generation system provided in this embodiment of the present application, in order to quickly reduce the voltage on the DC bus capacitor during fast shutdown, in a possible implementation, the switching transistor in the inverter may be controlled to perform a switching operation to consume electrical energy. Alternatively, it should be understood that in another possible implementation, the solar power generation system provided in this embodiment of the present application may consume electrical energy by using a fan. Indeed, in the solution provided in this embodiment of the present application, these two solutions may be combined to consume electrical energy by simultaneously using the fan, the switching transistor in the inverter, and the filter circuit. In addition, if the solar power generation system includes a filter circuit, when the switching transistor operates, the switching transistor and the filter circuit may form a path, so that electrical energy is consumed by using the impedance of the filter circuit, thereby further accelerating the drop in the DC bus voltage.

[0059] The solar power generation system provided in this embodiment of the present application is not limited to a specific topology of the inverter. For example, the inverter may be a T-type inverter or an I-type inverter, or may be an inverter with another topology. The inverter may be a three-phase inverter or a single-phase inverter. The solar power generation system in this embodiment of the present application may or may not include a filter circuit. In the following, only the three-phase T-type inverter including a filter circuit and shown in FIG. 4 is used as an example to describe the technical solution provided in the embodiment of the present application.

[0060] FIG. 4 is a schematic diagram of the structure of a DC / AC circuit in an inverter according to one embodiment of the present invention.

[0061] 4 shows the DC / AC circuit in a three-phase inverter. Since the structure of each phase is the same and each phase is a T-type topology, the following describes the structure of one phase and the working principle during fast shutdown with reference to the accompanying drawings. The circuit structures of the other two phases are similar, and the details are not described in this specification.

[0062] One phase in the DC / AC circuit provided in this embodiment of the present application includes a first switching transistor Q1, a second switching transistor Q2, a third switching transistor Q3, a fourth switching transistor Q4, an inductor L, and a capacitor Cf.

[0063] The first terminal of the third capacitor C3 is connected to the positive input terminal of the DC / AC circuit, i.e., connected to PV+. The second terminal of the third capacitor C3 is connected to the first terminal of the fourth capacitor C4. The second terminal of the fourth capacitor C4 is connected to the negative input terminal of the DC / AC circuit, i.e., connected to PV-.

[0064] A first terminal of the first switching transistor Q1 is connected to the positive input terminal PV+ of the DC / AC circuit. A second terminal of the first switching transistor Q1 is connected to the first terminal of the inductor L. A second terminal of the inductor L is connected to the first terminal of the capacitor Cf. A second terminal of the capacitor Cf is connected to the second terminal of the third capacitor C3. A second terminal of the fourth switching transistor Q4 is connected to the negative input terminal PV- of the DC / AC circuit. A first terminal of the fourth switching transistor Q4 is connected to the second terminal of the first switching transistor Q1. The second switching transistor Q2 and the third switching transistor Q3 are connected in series between the second terminal of the first switching transistor Q1 and the second terminal of the third capacitor C3.

[0065] Inductor L and capacitor Cf form the first phase filter circuit. Similarly, the filter circuits for each of the other two phases also include an inductor and a capacitor connected in series.

[0066] During fast shutdown, for example, when the first switching transistor Q1 and the fourth switching transistor Q4 are turned on to consume the electrical energy stored in the DC bus capacitor, it should be understood that the path of the discharge current on the DC bus capacitor is the first switching transistor Q1, the inductor L, and the capacitor Cf. Because the first switching transistor Q1, the inductor L, and the capacitor Cf all have internal resistances, when current flows through the first switching transistor Q1, the inductor L, and the capacitor Cf, the electrical energy is consumed by using the internal resistances of the aforementioned components. In addition, each switching transistor also includes switching losses and conduction losses. Because the switching transistors of the three-phase circuit are continuously turned on and off, the current in the filter circuit in which the inductor L is located changes continuously, and as a result, more electrical energy may be consumed. In this way, the electrical energy stored in the DC bus capacitor is quickly consumed. The inductor is used as an example. The inductor has copper loss and iron loss, and also has a skin effect, so that the higher the switching frequency is relative to the switching frequency of the switching transistor, the greater the electrical energy loss in the inductor. In this way, the electrical energy consumption on the DC bus capacitor can be accelerated, and as a result, the voltage at the input end of the inverter is quickly reduced to 30V or less.

[0067] In a possible implementation, the drive signal provided in the embodiments of the present application can be generated by using a modulation wave and a carrier wave. In order to accelerate electrical energy consumption and reduce the voltage at the input end of the inverter to 30 V or less as quickly as possible, the controller can change the frequency of the drive signal by changing the frequency of the carrier and send the changed drive signal to the switching transistor. For example, increasing the frequency of the drive signal, i.e., increasing the switching frequency of the switching transistor, can increase the rate at which the switching transistor and the filter circuit consume electrical energy. It should be understood that the frequency of the carrier wave generating the drive signal affects the frequency of the drive signal, and the frequency of the carrier wave is equal to the frequency of the drive signal generated by the carrier wave. Therefore, a higher frequency of the carrier results in a higher switching frequency of the inverter's switching transistor and a higher frequency of current change in the filter circuit, thereby resulting in greater power consumption by the switching transistor and the filter circuit.

[0068] In a possible implementation, the drive signal provided in the embodiment of the present application is generated by using a modulation wave and a carrier wave. In order to accelerate the consumption of electrical energy and reduce the voltage at the input end of the inverter to 30 V or less as quickly as possible, the controller can change the frequency of the modulation wave to change the drive signal and send the increased-frequency drive signal to the switching transistor, thereby increasing the rate at which the switching transistor and the filter circuit consume electrical energy. It should be understood that the frequency of the modulation wave generating the drive signal affects the frequency of the drive signal to some extent. A higher frequency of the modulation wave indicates a higher frequency of the drive signal generated by the modulation wave, which in turn results in a higher switching frequency of the switching transistor in the inverter and a higher frequency of current change in the filter circuit, thereby causing greater power consumption by the switching transistor and the filter circuit.

[0069] It should be noted that the frequency of the drive signal provided in the embodiment of the present application may be the drive signal frequency present during normal operation of the inverter, or may be a specific frequency set for fast shutdown of the inverter, which is not limited in the embodiment of the present application.

[0070] During a fast shutdown, the solar power generation system provided in the embodiments of the present application can consume electrical energy by using a switching transistor and a filter circuit, or in another possible implementation form, during a fast shutdown, the solar power generation system provided in the embodiments of the present application can consume electrical energy by using a fan, thereby reducing the voltage on the DC side of the inverter to below the reference required voltage as quickly as possible.

[0071] The following describes, with reference to the accompanying drawings, the technical solution in which the solar power generation system provided in the embodiments of the present application consumes electrical energy by using a fan.

[0072] FIG. 5 is a diagram illustrating the operating principle of a fan according to one embodiment of the present invention.

[0073] The fan 500 provided in this embodiment of the present application is powered by using an auxiliary power supply 800 and receives a control signal sent by the controller 700. It should be noted that the auxiliary power supply 800 is not an independent power supply, and the power source of the auxiliary power supply 800 may be a DC bus. When the controller 700 receives a fast shutdown command, the operation of the fan 500 may consume electrical energy from the auxiliary power supply 800, thereby reducing the voltage on the DC bus capacitor.

[0074] In this embodiment of the present application, when the controller 700 receives a fast shutdown command, the controller 700 turns on the fan and 500 to operate, thereby consuming the electrical energy stored in the DC bus capacitor and thereby achieving high-speed discharge of the DC bus capacitor. It should be understood that in the solution provided in the present application, in order to achieve high-speed discharge of the DC bus capacitor and reduce the voltage at the input end of the inverter to 30 V or less within 30 seconds, the power of the fan may be further controlled to be greater than the preset power, or the fan may be controlled to operate at a speed faster than the preset speed, thereby ensuring that the voltage at the input end of the inverter is reduced to 30 V or less within 30 seconds. In this embodiment of the present application, the preset power and the preset speed may be set based on actual requirements.

[0075] The following describes a specific implementation in which the solar power generation system provided in the embodiments of the present application consumes electrical energy by using a switching transistor and a filter circuit.

[0076] In the embodiment, an example including two photovoltaic power generation strings is still used for explanation, and each photovoltaic power generation string is described by using an example including two photovoltaic power generation modules. It should be understood that the photovoltaic power generation system may include more photovoltaic power generation strings, and each photovoltaic power generation string may include more photovoltaic power generation modules. In a possible implementation, the photovoltaic power generation system in the embodiment of the present application may further include an optimizer. The number of optimizers may have a one-to-one correspondence with the number of photovoltaic power generation modules, or multiple photovoltaic power generation modules may correspond to one optimizer. In other words, the number of optimizers may be proportional to the number of photovoltaic power generation modules. below For ease of explanation, in the embodiments of the present application, an example in which the number of optimizers is the same as the number of photovoltaic modules, and the optimizers have a one-to-one correspondence with the photovoltaic modules is used for explanation.

[0077] FIG. 6 is a schematic diagram of yet another solar power generation system structure according to an embodiment of the present invention.

[0078] The input of the inverter 100 is connected to a plurality of photovoltaic power generation strings, for example a first photovoltaic power generation string 300 and a second photovoltaic power generation string 400, which are connected in parallel with each other.

[0079] Each solar power generation string includes multiple solar power generation modules. For example, the first solar power generation string 300 includes solar power generation module 1-1 and solar power generation module 1-2, and the second solar power generation string 400 includes solar power generation module 2-1 and solar power generation module 2-2. In addition, the first solar power generation string 300 further includes optimizer 1-1 and optimizer 1-2, and the second solar power generation string 400 further includes optimizer 2-1 and optimizer 2-2.

[0080] For example, photovoltaic module 1-1 corresponds to optimizer 1-1, photovoltaic module 1-2 corresponds to optimizer 1-2, photovoltaic module 2-1 corresponds to optimizer 2-1, and photovoltaic module 2-2 corresponds to optimizer 2-2. The output terminal of each photovoltaic module is connected to the input terminal of the corresponding optimizer. For example, the output terminal of photovoltaic module 1-1 is connected to the input terminal of optimizer 1-1, the output terminal of photovoltaic module 1-2 is connected to the input terminal of optimizer 1-2, the output terminal of photovoltaic module 2-1 is connected to the input terminal of optimizer 2-1, and the output terminal of photovoltaic module 2-2 is connected to the input terminal of optimizer 2-2.

[0081] The output terminals of all the optimizers in the photovoltaic power generation string are connected in series with each other and connected to the input terminal of the inverter. For example, the outputs of the optimizer 1-1 and the optimizer 1-2 in the first photovoltaic power generation string 300 are connected in series with each other and connected to the input terminal of the inverter 100. That is, the outputs of the optimizer 1-1 and the optimizer 1-2 in the first photovoltaic power generation string 300 are connected in series with each other and connected to the input terminal of the inverter 100. inputThe output terminals of the optimizer 2-1 and the optimizer 2-2 in the second solar power generation string 400 are connected in series between the positive DC bus BUS+ and the negative DC bus BUS-, and the output terminals of the optimizer 2-1 and the optimizer 2-2 in the second solar power generation string 400 are connected in series with each other and connected to the input of the inverter 100. input The ends are connected in series between the positive DC bus BUS+ and the negative DC bus BUS-.

[0082] Optimizer 1-1 is configured to receive a fast shutdown command, stop operation, and disconnect from photovoltaic power generation module 1-1. Optimizer 1-2 is configured to receive a fast shutdown command, stop operation, and disconnect from photovoltaic power generation module 1-2. Optimizer 2-1 is configured to receive a fast shutdown command, stop operation, and disconnect from photovoltaic power generation module 2-1. Optimizer 2-2 is configured to receive a fast shutdown command, stop operation, and disconnect from photovoltaic power generation module 2-2.

[0083] It should be understood that for the solar power generation system in Figure 6, only the first solar power generation string 300 and the second solar power generation string 400 are used as examples to describe the technical solution in this application. In practical applications, the input end of the inverter 100 may be connected to one or more solar power generation strings, which is not limited in this embodiment of the application.

[0084] 6 is described by using an example in which the first solar power generation string 300 includes a solar cell module 1-1 and a solar cell module 1-2 connected in series. In a practical application, the first solar power generation string 300 or the second solar power generation string 400 may include one solar cell module or multiple solar cell modules connected in series with each other, which is not limited in this embodiment of the present application.

[0085] The optimizer in this embodiment of the present application is DC / It should be noted that the optimizer may be used for DC boost, or may be used for buck and boost, or for buck. For example, the optimizer in this embodiment of the present application may also include a boost circuit. In addition to the voltage boost function, the optimizer in this embodiment of the present application may further have a maximum power point tracking (MPPT) function. Since the optimizer tracks one corresponding photovoltaic power generation module, the optimizer can perform MPPT for the photovoltaic power generation module corresponding to the optimizer, thereby improving the electrical energy conversion efficiency of photovoltaic power generation.

[0086] In a possible implementation, the solar power generation system provided in this embodiment of the present application may further include a grid connection circuit breaker 900 connected between the output of the inverter 100 and the AC power grid 200. And, the controller 700 is further configured to control the grid connection circuit breaker 900 to disconnect the inverter 100 from the AC power grid 200 after receiving a fast shutdown command.

[0087] It should be understood that after receiving a fast shutdown command, the controller provided in this embodiment of the present application may first control the grid-tied circuit breaker to disconnect the inverter from the AC power grid. The aforementioned Grid-connected circuit circuit breaker After the controller disconnects the inverter from the AC power grid, the voltage at the input of the inverter is reduced in at least one of the following ways, where the at least one way includes the controller sending a drive signal to a switching transistor in the inverter, causing the switching transistor and a filter circuit to consume electrical energy, or the controller turning on a fan to consume electrical energy.

[0088] The output of the inverter provided in this embodiment of the present application may include a relay. Correspondingly, the output of the inverter is connected to a grid-connected circuit breaker by using a relay. The relay is configured to protect the inverter. The relay may be integrated in the inverter cabinet or may be independent from the inverter cabinet. This is not limited in this embodiment of the present application.

[0089] It should be noted that the inverter provided in this embodiment of the present application may be directly connected to the AC power grid, or may be connected to the AC power grid by using a transformer, i.e., the transformer is connected between the output of the inverter and the AC power grid. The transformer is configured to electrically isolate the inverter from the AC power grid. For example, the output of the inverter is connected to a primary winding of the transformer via a relay, and the secondary winding of the transformer is connected to the AC power grid via a grid-connected circuit breaker.

[0090] In a possible implementation, the solar power generation system provided in this embodiment of the present application may further include an upper computer 1000 .

[0091] The host computer 1000 sends a high-speed shutdown instruction to the controller 700 and the optimizers (optimizer 1-1, optimizer 1-2, optimizer 2-1, and optimizer 2-2).

[0092] It should be understood that the optimizers also have control functions. Each optimizer may correspond to one auxiliary controller, and the auxiliary controller can exercise control over the optimizer. For example, optimizer 1-2 includes auxiliary controller 1-2.

[0093] 6, in this embodiment of the present application, an example is used in which the host computer 1000 sends a fast shutdown command to the optimizer 1-2. The host computer 1000 sends the fast shutdown command to the auxiliary controller 1-2 corresponding to the optimizer 1-2, and the auxiliary controller 1-2 controls the optimizer 1-2 to stop operation and disconnect from the photovoltaic power generation module 1-2. The controller 700 and the auxiliary controller 1-2 are independent controllers.

[0094] In summary, when the photovoltaic inverter provided in this embodiment of the present application receives a fast shutdown command, the inverter controller sends a driving signal to the switching transistor, and the switching transistor performs a switching operation under the action of the driving signal. Here, a higher frequency of the driving signal indicates a larger power consumption caused by the switching operation of the switching transistor, or the inverter controller turns on the fan, so that the fan quickly consumes electrical energy. In the solution provided in this embodiment of the present application, alternatively, the controller can simultaneously drive the switching transistor and turn on the fan to consume electrical energy, thereby accelerating the electrical energy discharge of the DC bus capacitor, and thus increasing the DC side of the inverter, i.e., input Therefore, according to the solution provided in this embodiment of the present application, the discharge speed of the DC bus capacitor is increased without adding an additional energy absorption circuit, thereby accelerating the reduction of the DC bus voltage. This ensures that the inverter releases the electricity stored in the DC bus capacitor in a timely manner during fast shutdown. Therefore, the photovoltaic inverter provided in this embodiment of the present application can meet the standard requirements during fast shutdown. Here, the requirement is that the voltage on the DC side, i.e., the input end, is reduced to 30V or less within 30 seconds.

[0095] Method Embodiment

[0023] Based on the solar power generation system provided in the foregoing embodiments, the embodiments of the present application further provide a fast shutdown method for a solar power generation system. The following provides a detailed description with reference to the accompanying drawings.

[0096] The solar power generation system to which the fast shutdown method for a solar power generation system provided in the embodiment of the present application is applied may or may not include a filter circuit. This is not limited in the embodiment of the present application. If the solar power generation system provided in the embodiment of the present application does not include a filter circuit, electrical energy may be consumed by using a switching transistor under the action of a drive signal. In the following, FIG. 7 is used as an example to describe the fast shutdown method for a solar power generation system provided in one embodiment of the present application.

[0097] FIG. 7 is a flowchart of a fast shutdown method for a solar power generation system according to an embodiment of the present application.

[0098] The solar power generation system to which the fast shutdown method for a solar power generation system provided in this embodiment of the present application is applied includes an inverter and a fan. The inverter includes a switching transistor and a filter circuit. A solar power generation string and a DC bus capacitor are connected between a positive input terminal and a negative input terminal of the inverter. The inverter is configured to convert DC electricity provided by the solar power generation string into AC electricity and send the AC electricity to an AC power grid or a load. The method includes the following steps:

[0099] S701: A fast shutdown command is received.

[0100] S702: Reduce the voltage on the DC bus capacitor in at least one of the following ways: sending a drive signal to a switching transistor in the inverter, so that the switching transistor performs a switching operation under the action of the drive signal and consumes electrical energy, or turning on a fan, so that the fan consumes electrical energy.

[0101] In a possible implementation, the drive signal in this embodiment of the present application can be generated by using a modulating wave and a carrier wave. In this embodiment of the present application, sending the drive signal to the switching transistor in the inverter specifically includes changing the frequency of the carrier to change the frequency of the drive signal, and sending the changed drive signal to the switching transistor to increase the electrical energy consumed by the switching transistor and the filter circuit.

[0102] In a possible implementation, the drive signal in this embodiment of the present application is generated by using a modulating wave and a carrier. In this embodiment of the present application, sending the drive signal to the switching transistor in the inverter specifically includes changing the frequency of the modulating wave to change the drive signal, and sending the changed drive signal to the switching transistor to increase the electrical energy consumed by the switching transistor and the filter circuit.

[0103] In a possible implementation, turning on the fan in this embodiment of the present application specifically includes turning on the fan and controlling the fan to operate at a speed faster than a preset speed.

[0104] In a possible implementation, when the solar power generation system includes a filter circuit, the method provided in this embodiment of the present application further includes controlling a DC bus capacitor, a switching transistor, and the filter circuit to form a path, so that the filter circuit consumes electrical energy to reduce the voltage on the DC bus capacitor. For example, the filter circuit includes an inductor and a capacitor connected in series. Both the inductor and the capacitor have impedance, and electrical energy is consumed when a current passes through the impedance.

[0105] In summary, according to the fast shutdown method for a solar power generation system provided in this embodiment of the present application, after a fast shutdown command is received, a switching transistor is driven to perform a switching operation, or a fan is turned on to quickly consume electrical energy. Without adding additional hardware circuits, the speed of discharging the electricity stored in the DC bus capacitor during the fast shutdown is increased, so that the inverter can ensure that the electricity stored in the DC bus capacitor is discharged in a timely manner during the fast shutdown, thereby reducing the voltage on the DC side of the inverter to 30 V or less within 30 seconds.

[0106] Inverter Embodiment

[0013] Based on the solar power generation system and the fast shutdown method for the solar power generation system provided in the above embodiments, the embodiments of the present application further provide a solar power generation inverter. The following provides a detailed description with reference to the accompanying drawings.

[0107] The photovoltaic inverter provided in the embodiments of the present application may be a central inverter or a string inverter, and in the embodiments of the present application, the string inverter is used as an example for explanation.

[0108] The input terminal of the solar power inverter provided in the embodiment is usually connected to multiple solar power strings or can be connected to a single solar power string, which is not limited in this specification. The following provides an explanation by using an example in which the input terminal of the solar power inverter is connected to two solar power strings.

[0109] FIG. 8 is a schematic diagram of a structure of a photovoltaic inverter according to one embodiment of the present application.

[0110] The input end of the photovoltaic inverter 8000 in this embodiment of the present application is configured to connect to the first photovoltaic power string 300 and the second photovoltaic power string 400, respectively, and the output end of the photovoltaic inverter 8000 is configured to connect to the AC power grid 200.

[0111] In this embodiment of the present application, an example is used for illustration purposes in which the solar power inverter 8000 includes a filter circuit 802. Alternatively, the solar power inverter 8000 may not include a filter circuit.

[0112] 8, a solar power inverter 8000 provided in this embodiment of the present application includes a power conversion circuit 801, a filter circuit 802, a fan 804, and an inverter controller 803. The power conversion circuit 801 includes a switching transistor. The specific type of the switching transistor is not particularly limited in this embodiment of the present application, as long as the switching transistor is a controllable switching transistor.

[0113] A photovoltaic power generation string and a DC bus capacitor are connected between the positive and negative input terminals of the power conversion circuit 801. A filter circuit 802 is connected to the output terminal of the power conversion circuit.

[0114] The inverter controller 803 is configured to receive the fast shutdown command and reduce the voltage on the DC bus capacitor in at least one of the following ways: the inverter controller 803 sends a drive signal to the switching transistor so that the switching transistor and filter circuit 802 consume electrical energy; or the inverter controller 803 turns on the fan 804 to consume electrical energy.

[0115] It should be understood that this embodiment of the present application is a solution in which the fan 804 and the inverter controller 803 are integrated in a solar power inverter. In terms of actual function and effect, the inverter controller is equivalent to the controller in the above-mentioned embodiment, and the fan is equivalent to the fan in the above-mentioned embodiment. Correspondingly, in this embodiment of the present application, the frequency of the driving signal may be a non-fundamental frequency. For example, the driving signal sent by the inverter controller to the switching transistor may be a pulse-width modulated signal.

[0116] In a possible implementation, the drive signal in this embodiment of the present application is generated by using a modulating wave and a carrier, and the inverter controller is configured, among other things, to modify the frequency of the carrier to modify the frequency of the drive signal and to send the modified drive signal to the switching transistor to increase the electrical energy consumed by the switching transistor and the filter circuit.

[0117] In a possible implementation, the drive signal in this embodiment of the present application is generated by using a modulating wave and a carrier, and the inverter controller is configured, among other things, to change the frequency of the modulating wave to modify the drive signal and to send the modified drive signal to the switching transistor to increase the electrical energy consumed by the switching transistor and the filter circuit.

[0118] In a possible implementation, the solar power inverter in this embodiment of the present application further includes a filter circuit. The input of the power conversion circuit is connected to the solar power string, and the filter circuit is connected to the output of the power conversion circuit. When the inverter controller sends a drive signal to the switching transistor, the DC bus capacitor, the switching transistor, and the filter circuit form a path, so that the filter circuit consumes electrical energy to reduce the voltage on the DC bus capacitor.

[0119] In summary, after receiving a fast shutdown command, the solar power inverter provided in this embodiment of the present application drives a switching transistor to perform a switching operation or turns on a fan to quickly consume electrical energy. Without adding additional hardware circuits, the electrical discharge speed of the DC bus capacitor is increased, so as to ensure that the electricity stored in the DC bus capacitor is discharged in a timely manner during fast shutdown, and the voltage at the DC side, i.e., the input end, of the inverter is reduced to 30V or less within 30 seconds.

[0120] In this application, "at least on(item)" should be understood to mean one or more, and "a plurality of" should be understood to mean two or more. The term "and / or" is used to describe an associative relationship between related objects, and indicates that three relationships may exist. For example, "A and / or B" can represent three cases: only A is present, only B is present, or both A and B are present, where A and B may each be singular or plural. The character " / " generally indicates an "or" relationship between related objects. "At least one of the following items" or similar expressions refers to any combination of these items, including any combination of single items or multiple items. For example, at least one of a, b, or c can represent a, b, c, "a and b ("a and b")," "a and c ("a and c")," "b and c ("c and b")," or "a and b and c ("a and b and c")," where a, b, and c can each be singular or plural.

[0121] The foregoing embodiments do not limit the present application, but are merely intended to describe the technical solutions of the present application. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that, without departing from the essence of the corresponding technical solutions from the spirit and scope of the technical solutions in the embodiments of the present application, modifications can be further made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some technical features thereof.

Claims

1. A solar power generation system including an inverter and a controller, the inverter includes a power conversion circuit and a filter circuit, the power conversion circuit including a plurality of switching transistors, and the filter circuit including an inductor and a capacitor connected in series; a photovoltaic power string and a DC bus capacitor are connected between the positive and negative inputs of the inverter; an input terminal of the power conversion circuit is connected to the solar power generation string, and the filter circuit is connected to an output terminal of the power conversion circuit; The inverter is converting direct current electricity provided by the photovoltaic string into alternating current electricity; and transmitting the AC electricity to an AC power grid or to a load; It is structured as follows: The controller A fast shutdown command is received, and reducing the voltage on the DC bus capacitor by sending a drive signal by the controller to the switching transistor in the inverter such that the switching transistor performs a switching operation under the action of the drive signal to consume electrical energy; It is structured as follows: the driving signal is a pulse width modulated signal, and a higher switching frequency of the switching transistor indicates a higher electrical energy consumption; When the controller sends the drive signal to the switching transistor in the inverter, the DC bus capacitor, the switching transistor, and the inductor and the capacitor of the filter circuit form a path, and the switching transistor in the power conversion circuit is continuously turned on or off, and the current in the filter circuit in which the inductor is located changes continuously, so that the filter circuit consumes electrical energy to quickly reduce the voltage on the DC bus capacitor; A higher frequency of the drive signal indicates more electricity being consumed by inductors in the filter circuit. Solar power generation system.

2. The drive signal is generated by using a modulating wave and a carrier wave; The controller may in particular: Varying the frequency of the carrier wave to change the frequency of the drive signal; and transmitting the modified drive signal to the switching transistor; It is structured as follows: increasing the electrical energy consumed by the switching transistor; The solar power generation system according to claim 1 .

3. the drive signal is generated by using the modulating wave and the carrier wave; The controller may in particular: Varying the frequency of the modulated wave to vary the drive signal; and transmitting the modified drive signal to the switching transistor; It is structured as follows: increasing the electrical energy consumed by the switching transistor; The solar power generation system according to claim 2 .

4. The solar power generation system further includes an optimizer. The optimizer receiving the fast shutdown command; Stop operation, and Disconnect from the photovoltaic module, It is configured as follows: The photovoltaic power generation system according to any one of claims 1 to 3.

5. the solar power generation system further comprising a grid-connected circuit breaker connected between an output of the inverter and the AC power grid; The controller further comprises: controlling the grid-tied circuit breaker to disconnect the inverter from the AC power grid after receiving the fast shutdown command. It is configured as follows: The photovoltaic power generation system according to any one of claims 1 to 4.

6. The solar power generation system further includes a host computer. The host computer sending the fast shutdown command to the controller and the optimizer; It is configured as follows: The solar power generation system according to claim 4.

7. the frequency of the drive signal is a non-fundamental frequency; The photovoltaic power generation system according to any one of claims 1 to 6.

8. The inverter is a three-level T-type inverter. The photovoltaic power generation system according to any one of claims 1 to 7.

9. The controller is integrated into the inverter cabinet; and a fan is integrated within the inverter cabinet; The photovoltaic power generation system according to any one of claims 1 to 8.

10. The inverter is a string inverter or a central inverter. The photovoltaic power generation system according to any one of claims 1 to 9.

11. the solar power generation system further includes a fan; The controller further comprises: and configuring the controller to reduce a voltage on the DC bus capacitor by turning on the fan to consume electrical energy. The photovoltaic power generation system according to any one of claims 1 to 10.

12. A method for fast shutdown of a solar power generation system, comprising: The solar power generation system includes an inverter, the inverter includes a power conversion circuit and a filter circuit, the power conversion circuit includes a plurality of switching transistors, and the filter circuit includes an inductor and a capacitor connected in series; a photovoltaic power string and a DC bus capacitor are connected between the positive and negative inputs of the inverter; an input terminal of the power conversion circuit is connected to the solar power generation string, and the filter circuit is connected to an output terminal of the power conversion circuit; the inverter is configured to convert DC electricity provided by the solar power string into AC electricity and deliver the AC electricity to an AC power grid or to a load; The method comprises: receiving a fast shutdown command; reducing the voltage on the DC bus capacitor by sending a drive signal to a switching transistor in the inverter such that the switching transistor performs a switching operation under the action of the drive signal to consume electrical energy; the driving signal is a pulse width modulated signal, and a higher switching frequency of the switching transistor indicates a higher electrical energy consumption; When the drive signal is sent to the switching transistor in the inverter, The DC bus capacitor, the switching transistor, and the filter circuit are configured such that the inductor and the capacitor of the filter circuit form a path, the switching transistor in the power conversion circuit is continuously turned on or off, and the current in the filter circuit in which the inductor is located changes continuously, thereby consuming electrical energy and quickly reducing the voltage on the DC bus capacitor; A higher frequency of the drive signal indicates more electricity being consumed by inductors in the filter circuit. method.

13. The drive signal is generated by using a modulating wave and a carrier wave; transmitting the drive signal to the switching transistor in the inverter, Varying the frequency of the carrier wave to change the frequency of the drive signal; and transmitting a modified drive signal to the switching transistor; increasing the electrical energy consumed by the switching transistor and the filter circuit; The method of claim 12.

14. the drive signal is generated by using the modulating wave and the carrier wave; transmitting the drive signal to the switching transistor in the inverter, Varying the frequency of the modulated wave to vary the drive signal; and transmitting a modified drive signal to the switching transistor; increasing the electrical energy consumed by the switching transistor and the filter circuit; The method of claim 13.

15. A photovoltaic inverter comprising a power conversion circuit and an inverter controller, the power conversion circuit includes a plurality of switching transistors, and the filter circuit includes an inductor and a capacitor connected in series; a photovoltaic power generation string and a DC bus capacitor are connected between the positive input and the negative input of the power conversion circuit; The inverter controller A fast shutdown command is received, and reducing the voltage on the DC bus capacitor by sending a drive signal by the inverter controller to the switching transistor such that the switching transistor performs a switching operation under the action of the drive signal to consume electrical energy; It is structured as follows: the driving signal is a pulse width modulated signal, and a higher switching frequency of the switching transistor indicates a higher electrical energy consumption; When the inverter controller sends the drive signal to the switching transistor in the solar power inverter, The DC bus capacitor, the switching transistor, and the inductor and the capacitor of the filter circuit form a path, and the switching transistor in the power conversion circuit is continuously turned on or off, and the current in the filter circuit in which the inductor is located changes continuously, so that the filter circuit consumes electrical energy to quickly reduce the voltage on the DC bus capacitor; A higher frequency of the drive signal indicates more electricity being consumed by inductors in the filter circuit. Photovoltaic inverter.

16. The drive signal is generated by using a modulating wave and a carrier wave; The inverter controller, in particular, Varying the frequency of the carrier wave to change the frequency of the drive signal; and transmitting the modified drive signal to the switching transistor; It is structured as follows: increasing the electrical energy consumed by the switching transistor; 16. The photovoltaic inverter of claim 15.

17. the drive signal is generated by using the modulating wave and the carrier wave; The inverter controller, in particular, Varying the frequency of the modulated wave to vary the drive signal; and transmitting the modified drive signal to the switching transistor; It is structured as follows: increasing the electrical energy consumed by the switching transistor; 17. The photovoltaic inverter of claim 16.

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