CN117674255A - Control method, controller and photovoltaic system - Google Patents

Abstract

The application provides a control method, a controller and a photovoltaic system. The method is applied to a photovoltaic system connected with a power grid, and comprises the following steps: judging whether the power grid is in a high-voltage state or a low-voltage state; when the power grid is in a high-voltage state, regulating a derating coefficient according to a first voltage so as to control the active power output by the photovoltaic system not to exceed a first limit power, wherein the first voltage is the bus voltage of the photovoltaic system, the derating coefficient is used for regulating a voltage feedback value of a bus voltage loop, and the voltage feedback value is reduced along with the reduction of the derating coefficient; when the power grid is in a low-voltage state, the derating coefficient is adjusted according to the ratio of the first voltage to the second voltage so as to control the active power output by the photovoltaic system not to exceed the second limiting power, wherein the second voltage is the power grid voltage. The photovoltaic system and the power grid working reliability can be improved.

Description

Control method, controller and photovoltaic system

Technical field

This application relates to the field of photovoltaic control technology, and in particular to a control method, controller and photovoltaic system.

Background technique

When the photovoltaic system is connected to the power grid, in some cases, such as excessive nonlinear load on the line or too high line impedance, the power grid may be in a weak grid state and the power grid has poor anti-disturbance performance. In a weak grid state, when the grid voltage is abnormal, if the grid requests the photovoltaic system to output active power for support, the output power may fluctuate due to the voltage fluctuation of the photovoltaic system, which may further aggravate the grid disturbance and affect the work of the photovoltaic system and the grid. reliability.

This application provides a control method to ensure the reliability of the photovoltaic system and the power grid under weak grid conditions.

Contents of the invention

Embodiments of the present application provide a control method, a controller and a photovoltaic system to ensure the operational reliability of the photovoltaic system and the power grid in a weak power grid state.

In the first aspect, embodiments of the present application provide a control method applied to a photovoltaic system connected to the power grid, including:

Determine whether the power grid is in a high-voltage state or a low-voltage state. The high-voltage state is a working state in which the grid voltage is greater than the rated maximum voltage of the grid. The low-voltage state is a working state in which the grid voltage is less than the rated minimum voltage of the grid;

When the power grid is in a high-voltage state, the derating coefficient is adjusted according to the first voltage to control the active power output by the photovoltaic system not to exceed the first limit power. The first voltage is the bus voltage of the photovoltaic system, and the derating coefficient is used to adjust the bus voltage loop. The voltage feedback value of the circuit, the voltage feedback value decreases as the derating coefficient decreases;

When the power grid is in a low-voltage state, the derating coefficient is adjusted according to the ratio of the first voltage and the second voltage to control the active power output by the photovoltaic system not to exceed the second limit power, and the second voltage is the power grid voltage.

In a possible implementation, adjusting the derating coefficient according to the first voltage includes:

When the first voltage exceeds the preset voltage, the derating coefficient is controlled to decrease until the first voltage does not exceed the preset voltage.

In a possible implementation, after controlling the reduction of the derating coefficient, the control method further includes:

If the power grid returns to the normal state from high voltage, the control derating coefficient is restored to the default value.

In a possible implementation, the derating coefficient is adjusted according to the ratio of the first voltage and the second voltage, including:

When the ratio exceeds the preset ratio, the derating coefficient is controlled to decrease until the ratio does not exceed the preset ratio.

In a possible implementation, after controlling the reduction of the derating coefficient, the control method further includes:

If the power grid returns to the normal state from the low voltage state, the control derating coefficient is restored to the default value.

In one possible implementation, determining whether the power grid is in a high-voltage state or a low-voltage state includes:

When receiving the active power request from the grid, the grid voltage is obtained, and the grid is judged to be in a high-voltage state or a low-voltage state based on the grid voltage.

In the second aspect, this application provides a control device applied to a photovoltaic system connected to the power grid, including:

A judgment module is used to determine whether the power grid is in a high-voltage state or a low-voltage state. The high-voltage state is a working state in which the grid voltage is greater than the grid's rated maximum voltage, and the low-voltage state is a working state in which the grid voltage is less than the grid's rated minimum voltage;

The first control module is used to adjust the derating coefficient according to the first voltage when the power grid is in a high voltage state to control the active power output by the photovoltaic system not to exceed the limited power. The first voltage is the bus voltage of the photovoltaic system, and the derating coefficient is For regulating the voltage feedback value of the bus voltage loop, the voltage feedback value decreases as the derating coefficient decreases;

The second control module is used to adjust the derating coefficient according to the ratio of the first voltage and the second voltage to control the active power output by the photovoltaic system not to exceed the limited power when the power grid is in a low-voltage state. The second voltage is the grid voltage.

In a third aspect, embodiments of the present application provide a controller, including a memory and a processor. The memory stores a computer program that can be run on the processor. When the processor executes the computer program, the above first aspect or aspects are implemented. Any possible implementation controls the steps of the method.

In a fourth aspect, embodiments of the present application provide a photovoltaic system, including the controller of the third aspect.

In a fifth aspect, embodiments of the present application provide a computer-readable storage medium. The computer-readable storage medium stores a computer program. When the computer program is executed by a processor, the above first aspect or any of the possible aspects of the first aspect can be implemented. Implement the steps of a control method.

Embodiments of the present application provide a control method, a controller and a photovoltaic system. When the power grid is in a high-voltage state, the derating coefficient is adjusted according to the bus voltage of the photovoltaic system to reduce the output power of the photovoltaic system and ensure that the bus voltage of the photovoltaic system is not is raised to avoid outputting higher active power from affecting the stability of the power grid. When the power grid is in a low-voltage state, the derating coefficient is adjusted according to the ratio of the bus voltage and the grid voltage to reduce the bus voltage to avoid outputting higher active power from affecting the stability of the power grid and ensure the reliability of the power grid and photovoltaic systems.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments or description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only for the purpose of the present application. For some embodiments, for those of ordinary skill in the art, other drawings can be obtained based on these drawings without exerting creative efforts.

Figure 1 is a schematic structural diagram of a photovoltaic system provided by an embodiment of the present application;

Figure 2 is an implementation flow chart of the control method provided by the embodiment of the present application;

Figure 3 is a schematic structural diagram of a control device provided by an embodiment of the present application;

Figure 4 is a schematic diagram of a controller provided by an embodiment of the present application.

Detailed ways

In the following description, for the purpose of explanation rather than limitation, specific details such as specific system structures and technologies are provided to provide a thorough understanding of the embodiments of the present application. However, it will be apparent to those skilled in the art that the present application may be practiced in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present application with unnecessary detail.

In order to make the purpose, technical solutions and advantages of the present application clearer, specific embodiments will be described below in conjunction with the accompanying drawings.

Figure 1 is a schematic structural diagram of a photovoltaic system provided by an embodiment of the present application. As shown in Figure 1, the photovoltaic system may include photovoltaic modules, DC/DC modules, and DC/AC modules connected in sequence. Among them, the other end of the DC/AC module is connected to the power grid.

In the embodiment of the present application, the DC bus between the DC/DC module and the DC/AC module is the busbar of the photovoltaic system, and the connection point between the DC/AC module and the power grid is the connection point between the photovoltaic system and the power grid.

The photovoltaic system is connected to the power grid. When the power grid is weak, the power grid has poor anti-disturbance performance. When the power grid is in an abnormal state, the voltage at the grid connection point where the photovoltaic system is connected to the grid fluctuates, which may affect the output active power of the photovoltaic system. This may further aggravate the fluctuation of the power grid, affecting both the reliability of the grid and the work of the photovoltaic system. reliability.

The embodiment of the present application provides a control method for a light system to solve the problem of mutual interaction between the power grid and the photovoltaic system under a weak power grid.

Refer to Figure 2, which shows an implementation flow chart of the control method provided by the embodiment of the present application. As shown in Figure 2, a control method applied to a photovoltaic system connected to the power grid may include S101 to S103.

S101. Determine whether the power grid is in a high-voltage state or a low-voltage state. The high-voltage state is a working state in which the grid voltage is greater than the grid's rated maximum voltage, and the low-voltage state is a working state in which the grid voltage is less than the grid's rated minimum voltage.

The execution subject of the embodiment of the present application may be the overall controller of the photovoltaic system or the controller of the inverter in the photovoltaic system.

The embodiment of the present application can monitor the voltage of the power grid. When the grid voltage is greater than the rated maximum voltage of the grid, it can be determined that the grid is in a high-voltage state. When the grid voltage is less than the rated minimum voltage of the grid, it can be determined that the grid is in a low-voltage state. When the grid voltage is less than or equal to the rated maximum voltage of the grid and greater than or equal to the rated minimum voltage of the grid, it can be determined that the grid is in a normal state. Among them, both the high-voltage state and the low-voltage state are abnormal states of the power grid.

Optionally, it can be determined in real time whether the power grid is in a high-voltage state or a low-voltage state. Or, when receiving an active power request from the power grid, it is determined that the power grid is in a high-voltage state or a low-voltage state. Among them, active power request is used to indicate that the grid requests the photovoltaic system to output active power.

S102, when the power grid is in a high-voltage state, adjust the derating coefficient according to the first voltage to control the active power output by the photovoltaic system not to exceed the first limit power. The first voltage is the bus voltage of the photovoltaic system, and the derating coefficient is used to adjust the bus. The voltage feedback value of the voltage loop, the voltage feedback value decreases as the derating coefficient decreases.

When the grid voltage is greater than the rated maximum voltage of the grid, it indicates that the grid is in a high-voltage state. When the power grid is in a high-voltage state, the voltage at the connection point between the photovoltaic system and the power grid may be raised, causing the bus voltage of the photovoltaic system to rise, thus affecting the stability of the photovoltaic system. The increase in the bus voltage leads to an increase in the output active power. In the case of a weak grid, the power grid has poor anti-interference performance, which in turn affects the stability of the power grid. Ultimately, the operating reliability of both the power grid and the photovoltaic system is reduced.

When the power grid is in a high-voltage state, the derating coefficient can be adjusted according to the first voltage to reduce the active power output by the photovoltaic system and prevent the bus voltage of the photovoltaic system from being too high.

The bus voltage of the photovoltaic system is adjusted by the bus voltage loop. The bus voltage loop adjusts the bus voltage according to the voltage feedback value and the given bus voltage to prevent the bus voltage from being too high or too low. When the voltage feedback value increases, the bus voltage increases; when the voltage feedback value decreases, the bus voltage decreases. By adjusting the derating factor reduction, the bus voltage reduction can be adjusted.

In practical applications, the bus voltage is proportional to the active power. When the bus voltage increases, the active power output by the photovoltaic system increases. When the bus voltage decreases, the active power output by the photovoltaic system decreases. Therefore, by adjusting the derating coefficient, the bus voltage can be adjusted, thereby adjusting the active power output by the photovoltaic system. That is, the active power output by the photovoltaic system decreases as the derating coefficient decreases.

In the embodiment of the present application, the first voltage is the bus voltage of the photovoltaic system. When the first voltage is too high, the output active power of the photovoltaic system may be too high. At this time, the derating coefficient can be adjusted to limit the first voltage, thereby ensuring that the active power output by the photovoltaic system does not exceed the first limit power. Among them, the first limited power is the maximum allowable output active power of the photovoltaic system under the high voltage state of the grid. Or the first limited power is or the power value of the photovoltaic system is less than the maximum allowable output active power under the high voltage state of the power grid.

S103. When the power grid is in a low-voltage state, adjust the derating coefficient according to the ratio of the first voltage and the second voltage to control the active power output by the photovoltaic system not to exceed the second limit power. The second voltage is the power grid voltage.

In the embodiment of the present application, the ratio of the first voltage and the second voltage may be called a voltage difference coefficient. When the grid voltage is less than the rated minimum voltage of the grid, it indicates that the grid is at low voltage. When the bus voltage and grid voltage are normal, the pressure difference coefficient is within the normal range. When the power grid is in a low-voltage state, the bus voltage will also decrease under normal circumstances to ensure that the pressure difference coefficient is within the normal range. However, if the pressure difference coefficient increases, it means that the bus voltage increases or remains unchanged, which may cause the active power output of the photovoltaic system to increase, thereby disturbing the power grid. Grid fluctuations in turn also affect the photovoltaic system. The stability of the system will ultimately lead to a reduction in the working reliability of both the power grid and the photovoltaic system.

When the power grid is in a low-voltage state and the pressure difference coefficient is too high, the derating coefficient can be adjusted to reduce the bus voltage of the photovoltaic system, thereby ensuring that the active power output by the photovoltaic system does not exceed the second limit power. Among them, the second limited power is the maximum allowable output active power of the photovoltaic system under low voltage state of the grid. Or the second limited power is the power value of the photovoltaic system that is less than the maximum allowable output active power in the low voltage state of the grid.

The embodiment of this application reduces the output power of the photovoltaic system by adjusting the derating coefficient according to the bus voltage of the photovoltaic system when the power grid is in a high-voltage state, ensuring that the bus voltage of the photovoltaic system is not raised and avoiding the impact of higher active power output. The stability of the power grid. When the power grid is in a low-voltage state, the derating coefficient is adjusted according to the ratio of the bus voltage and the grid voltage to reduce the bus voltage to avoid outputting higher active power from affecting the stability of the power grid and ensure the reliability of the power grid and photovoltaic systems.

In some embodiments of the present application, the "adjusting the derating coefficient according to the first voltage" in S102 above may include:

When the first voltage exceeds the preset voltage, the derating coefficient is controlled to decrease until the first voltage does not exceed the preset voltage.

When the first voltage does not exceed the preset voltage, the derating coefficient remains unchanged.

When the grid voltage is greater than the rated maximum voltage of the grid, the grid voltage is in a high voltage state. At this time, if the bus voltage exceeds the preset voltage, it indicates that the bus voltage is too high. At this time, the derating coefficient can be controlled to gradually decrease to reduce the bus voltage until the bus voltage does not exceed the preset voltage to control the output of the photovoltaic system. The active power does not exceed the first limit power.

Optionally, the derating factor can be gradually and linearly reduced until the bus voltage does not exceed the preset voltage. Or, gradually reduce the derating coefficient according to the preset reduction value until the bus voltage does not exceed the preset voltage. The specific choice can be made according to the actual situation.

Embodiments of the present application may control the derating coefficient to decrease until the first voltage does not exceed the preset voltage when the first voltage exceeds the preset voltage and the duration for which the first voltage exceeds the preset voltage exceeds the first preset time period.

When the first voltage exceeds the preset voltage, but the duration for which the first voltage exceeds the preset voltage does not exceed the first preset time, the derating coefficient remains unchanged.

In the embodiment of the present application, when the power grid is in a normal state, the derating coefficient is set to a default value. When the power grid is in a high-voltage state, the derating coefficient can be controlled to gradually decrease from the default value. Among them, the default value can be 1.

The embodiment of the present application gradually controls the reduction of the derating coefficient when the power grid is in a high-voltage state to reduce the bus voltage, thereby reducing the active power output by the photovoltaic system and maintaining the stability of the power grid and the stability of the photovoltaic system.

In some embodiments of the present application, after controlling the reduction of the derating coefficient, the control method may further include:

If the power grid returns to the normal state from high voltage, the control derating coefficient is restored to the default value.

The normal state is a working state where the grid voltage is not less than the rated minimum voltage of the grid and not greater than the rated maximum voltage of the grid.

After the control derating coefficient is reduced, if the grid returns to the normal state from the high voltage state, it means that the grid voltage returns to the normal value. The voltage of the grid connection point connecting the photovoltaic system and the grid returns to the normal voltage from the high voltage. The voltage feedback of the bus voltage loop The value decreases. At this time, the derating coefficient can be adjusted to gradually increase to the default value to avoid the bus voltage from being too low.

By adjusting the derating coefficient to return to the default value after the power grid returns to a normal state, the embodiment of the present application can avoid power grid fluctuations as much as possible and ensure the working reliability of the photovoltaic system and the working reliability of the power grid.

In some embodiments of the present application, "Adjust the derating coefficient according to the ratio of the first voltage and the second voltage" in S103 above may include:

When the ratio exceeds the preset ratio, the derating coefficient is controlled to decrease until the ratio does not exceed the preset ratio.

When the ratio does not exceed the preset ratio, the derating coefficient remains unchanged.

When the grid voltage is lower than the rated minimum voltage of the grid, the grid voltage is in a low voltage state. At this time, if the ratio of the bus voltage to the grid voltage exceeds the preset ratio, it indicates that the bus voltage is relatively too high. At this time, the derating coefficient can be controlled to gradually decrease to reduce the bus voltage until the ratio of the bus voltage to the grid voltage The preset ratio is not exceeded, so that the active power output by the photovoltaic system is controlled not to exceed the second limit power.

Optionally, the derating coefficient can be gradually and linearly reduced until the ratio of the bus voltage to the grid voltage does not exceed the preset ratio. Or, gradually reduce the derating coefficient according to the preset reduction value until the ratio of the bus voltage to the grid voltage does not exceed the preset ratio. The specific choice can be made according to the actual situation.

Embodiments of the present application can control the derating coefficient to decrease when the ratio of the first voltage to the second voltage exceeds the preset ratio, and the duration of the ratio of the first voltage to the second voltage exceeding the preset ratio exceeds the second preset period. Small until the ratio of the first voltage and the second voltage does not exceed the preset ratio.

When the first voltage exceeds the preset voltage, but the duration for which the first voltage exceeds the preset voltage does not exceed the first preset time, the derating coefficient remains unchanged.

The embodiment of the present application gradually controls the reduction of the derating coefficient when the power grid is in a low-voltage state to reduce the bus voltage, thereby reducing the active power output by the photovoltaic system and maintaining the stability of the power grid and the stability of the photovoltaic system.

In some embodiments of the present application, after controlling the reduction of the derating coefficient, the control method further includes:

If the power grid returns to the normal state from the low voltage state, the control derating coefficient is restored to the default value.

After controlling the reduction of the derating coefficient, if the power grid returns from the low voltage state to the normal state, the derating coefficient can be adjusted to gradually increase to the default value to ensure that the ratio of the bus voltage to the grid voltage does not exceed the preset ratio.

By adjusting the derating coefficient to return to the default value after the power grid returns to a normal state, the embodiment of the present application can avoid power grid fluctuations as much as possible and ensure the working reliability of the photovoltaic system and the working reliability of the power grid.

In some embodiments of this application, "determining whether the power grid is in a high-voltage state or a low-voltage state" in S101 above may include:

When receiving the active power request from the grid, the grid voltage is obtained, and the grid is judged to be in a high-voltage state or a low-voltage state based on the grid voltage.

When no active power request from the grid is received, the grid voltage is not obtained, and the grid working status is not judged.

When the power grid needs to be supported by the active power of the photovoltaic system, it can send an active power request to the photovoltaic system. When the photovoltaic system receives an active power request, it can obtain the grid voltage and determine the current working status of the grid.

When the grid voltage is greater than the rated maximum voltage of the grid, it is determined that the grid is in a high-voltage state. When the grid voltage is less than the rated minimum voltage of the grid, the grid is determined to be in a low-voltage state.

The embodiment of the present application executes corresponding control logic when receiving an active power request from the power grid to maintain the stability of the power grid and the photovoltaic system and avoid mutual influence between the photovoltaic system and the power grid under weak power grid conditions.

It should be understood that the sequence number of each step in the above embodiment does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiment of the present application.

The following are device embodiments of the present application. For details that are not described in detail, reference may be made to the above corresponding method embodiments.

Figure 3 shows a schematic structural diagram of the control device provided by the embodiment of the present application. For convenience of explanation, only the parts related to the embodiment of the present application are shown. The details are as follows:

As shown in Figure 3, the control device 20 is applied to a photovoltaic system connected to the power grid. The control device includes:

The determination module 201 is used to determine whether the power grid is in a high-voltage state or a low-voltage state. The high-voltage state is a working state in which the grid voltage is greater than the grid's rated maximum voltage, and the low-voltage state is a working state in which the grid voltage is less than the grid's rated minimum voltage;

The first control module 202 is used to adjust the derating coefficient according to the first voltage when the power grid is in a high voltage state to control the active power output by the photovoltaic system not to exceed the limited power. The first voltage is the bus voltage of the photovoltaic system, and the derating coefficient It is used to adjust the voltage feedback value of the bus voltage loop. The voltage feedback value decreases as the derating coefficient decreases;

The second control module 203 is used to adjust the derating coefficient according to the ratio of the first voltage and the second voltage to control the active power output by the photovoltaic system not to exceed the limited power when the power grid is in a low-voltage state. The second voltage is the grid voltage. Can include:

In some embodiments of the present application, the first control module 202 is also used to control the derating coefficient to decrease when the first voltage exceeds the preset voltage until the first voltage does not exceed the preset voltage.

In some embodiments of the present application, the control device 20 may also include:

The third control module is used to control the derating coefficient to return to the default value if the power grid returns to the normal state from the high voltage state after the derating coefficient is reduced.

In some embodiments of the present application, the second control module 203 is also used to control the derating coefficient to decrease until the ratio does not exceed the preset ratio when the ratio exceeds the preset ratio.

In some embodiments of the present application, the control device 20 may also include:

The fourth control module is used to control the derating coefficient to return to the default value if the power grid returns to the normal state from the low voltage state after the derating coefficient is reduced.

In some embodiments of the present application, the determination module 201 is also used to obtain the grid voltage when receiving an active power request from the grid, and determine whether the grid is in a high-voltage state or a low-voltage state based on the grid voltage.

Figure 4 is a schematic diagram of a controller provided by an embodiment of the present application. As shown in FIG. 4 , the controller 30 of this embodiment includes: a processor 300 and a memory 301 . The memory 301 stores a computer program 302 that can run on the processor 300 . When the processor 300 executes the computer program 302, the steps in each of the above control method embodiments are implemented. Alternatively, when the processor 300 executes the computer program 302, the functions of each module/unit in each of the above device embodiments are implemented.

For example, the computer program 302 can be divided into one or more modules/units, and one or more modules/units are stored in the memory 301 and executed by the processor 300 to complete the present application. One or more modules/units may be a series of computer program instruction segments capable of completing specific functions. The instruction segments are used to describe the execution process of the computer program 302 in the controller 30 .

The controller 30 may be a controller of a photovoltaic system or a controller of an inverter. The controller 30 may include, but is not limited to, a processor 300 and a memory 301. Those skilled in the art can understand that FIG. 4 is only an example of the controller 30 and does not constitute a limitation on the controller 30. It may include more or fewer components than shown, or some components may be combined, or different components may be used. , for example, the controller may also include input and output devices, network access devices, buses, etc.

The processor 300 may be a central processing unit (CPU), or other general-purpose processor, a digital signal processor (Digital Signal Processor, DSP), an application specific integrated circuit (Application Specific Integrated Circuit, ASIC), Field-Programmable Gate Array (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or the processor may be any conventional processor, etc.

The memory 301 may be an internal storage unit of the controller 30 , such as a hard disk or memory of the controller 30 . The memory 301 can also be an external storage device of the controller 30, such as a plug-in hard disk, a smart memory card (Smart Media Card, SMC), a secure digital (SD) card, a flash memory card (Flash) equipped on the controller 30. Card) etc. Further, the memory 301 may also include both an internal storage unit of the controller 30 and an external storage device. Memory 301 is used to store computer programs and other programs and data required by the controller. The memory 301 can also be used to temporarily store data that has been output or is to be output.

Those skilled in the art can clearly understand that for the convenience and simplicity of description, only the division of the above functional units and modules is used as an example. In actual applications, the above functions can be allocated to different functional units and modules according to needs. Module completion means dividing the internal structure of the device into different functional units or modules to complete all or part of the functions described above. Each functional unit and module in the embodiment can be integrated into one processing unit, or each unit can exist physically alone, or two or more units can be integrated into one unit. The above-mentioned integrated unit can be hardware-based. It can also be implemented in the form of software functional units. In addition, the specific names of each functional unit and module are only for the convenience of distinguishing each other and are not used to limit the scope of protection of the present application. For the specific working processes of the units and modules in the above system, reference can be made to the corresponding processes in the foregoing method embodiments, which will not be described again here.

An embodiment of the present application also provides a photovoltaic system, including the above controller 30.

In the above embodiments, each embodiment is described with its own emphasis. For parts that are not detailed or documented in a certain embodiment, please refer to the relevant descriptions of other embodiments.

Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented with electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Skilled artisans may implement the described functionality using different methods for each specific application, but such implementations should not be considered beyond the scope of this application.

In the embodiments provided in this application, it should be understood that the disclosed device/controller and method can be implemented in other ways. For example, the device/controller embodiments described above are only illustrative. For example, the division of modules or units is only a logical function division. In actual implementation, there may be other division methods, such as multiple units or components. can be combined or can be integrated into another system, or some features can be ignored, or not implemented. On the other hand, the coupling or direct coupling or communication connection between each other shown or discussed may be through some interfaces, indirect coupling or communication connection of devices or units, which may be in electrical, mechanical or other forms.

A unit described as a separate component may or may not be physically separate. A component shown as a unit may or may not be a physical unit, that is, it may be located in one place, or it may be distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

In addition, each functional unit in each embodiment of the present application can be integrated into one processing unit, each unit can exist physically alone, or two or more units can be integrated into one unit. The above integrated units can be implemented in the form of hardware or software functional units.

Integrated modules/units may be stored in a computer-readable storage medium if implemented in the form of software functional units and sold or used as independent products. Based on this understanding, the present application can implement all or part of the processes in the methods of the above embodiments, and can also use a computer program to instruct relevant hardware to complete the process. The computer program can be stored in a computer-readable storage medium, and the computer program can be stored in a computer-readable storage medium. When executed by the processor, the steps of each of the above control method embodiments can be implemented. Among them, the computer program includes computer program code, and the computer program code can be in the form of source code, object code, executable file or some intermediate form, etc. Computer-readable media may include: any entity or device that can carry computer program code, recording media, USB flash drives, mobile hard drives, magnetic disks, optical disks, computer memory, read-only memory (Read-Only Memory, ROM), random access Memory (Random Access Memory, RAM), electrical carrier signals, telecommunications signals, and software distribution media, etc.

The above embodiments are only used to illustrate the technical solutions of the present application, but are not intended to limit them. Although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments. Modifications are made to the recorded technical solutions, or equivalent substitutions are made to some of the technical features; these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and shall be included in this application. within the scope of protection.

Claims (10)

1. A control method, characterized by being applied to a photovoltaic system connected to an electric grid, comprising:

judging whether the power grid is in a high-voltage state or a low-voltage state, wherein the high-voltage state is a working state that the power grid voltage is larger than the rated maximum voltage of the power grid, and the low-voltage state is a working state that the power grid voltage is smaller than the rated minimum voltage of the power grid;

when the power grid is in a high-voltage state, regulating a derating coefficient according to a first voltage so as to control the active power output by the photovoltaic system not to exceed a first limiting power, wherein the first voltage is the bus voltage of the photovoltaic system, the derating coefficient is used for regulating a voltage feedback value of a bus voltage loop, and the voltage feedback value is reduced along with the reduction of the derating coefficient;

when the power grid is in a low-voltage state, the derating coefficient is adjusted according to the ratio of the first voltage to the second voltage so as to control the active power output by the photovoltaic system not to exceed the second limiting power, wherein the second voltage is the power grid voltage.

2. The control method according to claim 1, wherein the adjusting the derating factor according to the first voltage includes:

and when the first voltage exceeds a preset voltage, controlling the derating coefficient to decrease until the first voltage does not exceed the preset voltage.

3. The control method according to claim 2, characterized in that after controlling the derating coefficient to decrease, the control method further comprises:

and if the power grid is recovered to a normal state from a high-voltage state, controlling the derating coefficient to recover to a default value.

4. The control method according to claim 1, wherein the adjusting the derating coefficient according to the ratio of the first voltage and the second voltage includes:

and when the ratio exceeds a preset ratio, controlling the derating coefficient to be reduced until the ratio does not exceed the preset ratio.

5. The control method according to claim 4, characterized in that after controlling the derating coefficient to decrease, the control method further comprises:

and if the power grid is recovered to a normal state from a low-voltage state, controlling the derating coefficient to recover to a default value.

6. The control method according to any one of claims 1 to 5, characterized in that the determining that the power grid is in a high-voltage state or a low-voltage state includes:

and when the active request of the power grid is received, acquiring the power grid voltage, and judging whether the power grid is in a high-voltage state or a low-voltage state according to the power grid voltage.

7. A control device for use in a photovoltaic system connected to an electrical grid, the control device comprising:

the judging module is used for judging whether the power grid is in a high-voltage state or a low-voltage state, wherein the high-voltage state is a working state that the power grid voltage is larger than the rated maximum voltage of the power grid, and the low-voltage state is a working state that the power grid voltage is smaller than the rated minimum voltage of the power grid;

the first control module is used for adjusting a derating coefficient according to a first voltage when the power grid is in a high-voltage state so as to control the active power output by the photovoltaic system not to exceed the limit power, wherein the first voltage is the bus voltage of the photovoltaic system, the derating coefficient is used for adjusting a voltage feedback value of a bus voltage loop, and the voltage feedback value is reduced along with the reduction of the derating coefficient;

and the second control module is used for adjusting the derating coefficient according to the ratio of the first voltage to the second voltage when the power grid is in a low-voltage state so as to control the active power output by the photovoltaic system not to exceed the limit power, wherein the second voltage is the power grid voltage.

8. A controller comprising a memory and a processor, in which a computer program is stored which is executable on the processor, characterized in that the processor, when executing the computer program, carries out the steps of the control method according to any one of the preceding claims 1 to 6.

9. A photovoltaic system comprising the controller of claim 8.

10. A computer-readable storage medium storing a computer program, characterized in that the computer program, when executed by a processor, implements the steps of the control method according to any one of the preceding claims 1 to 6.