Control method and system for participation of photovoltaic power generation system in power grid frequency modulation

Abstract

The invention discloses a control method and system for a photovoltaic power generation system to participate in power grid frequency modulation. The method comprises the following steps: monitoring a frequency signal of a power grid in real time through a frequency measuring device; when the monitored power grid frequency deviates from the rated frequency, recording a power grid frequency deviation value; determining the working condition of the power grid according to the recorded power grid frequency deviation, and calculating the output power regulation quantity of the photovoltaic power generation system by adopting a preset frequency regulation control algorithm; judging whether the frequency modulation capability of the photovoltaic power generation system reaches a preset condition or not according to the output capability of the photovoltaic power generation system; if yes, performing frequency modulation on the power grid only through the photovoltaic power generation system; otherwise, assisting the photovoltaic power generation system to jointly participate in frequency modulation through the energy storage system. Existing photovoltaic power generation facilities and energy storage systems are utilized to participate in power grid frequency modulation, the frequency modulation cost can be greatly reduced, economic benefits of a photovoltaic power generation system can be improved, and development and expansion of the new energy industry can be promoted.

Description

Technical Field

[0001] The invention relates to a control method and system for a photovoltaic power generation system to participate in power grid frequency modulation, belonging to power system frequency modulation technology. Background Art

[0002] With the increasing global awareness of environmental protection and the transformation of energy structure, the development and utilization of renewable energy has become the focus of attention of countries around the world. Among them, photovoltaic power generation, as one of the most promising and fastest-growing renewable energy technologies, has shown a rapid growth in installed capacity and power generation worldwide. Photovoltaic power generation uses solar energy to directly convert into electrical energy, which not only reduces the consumption of fossil fuels, but also reduces greenhouse gas emissions, which is of great significance for mitigating global climate change.

[0003] However, the output characteristics of photovoltaic power generation have brought new challenges to the stable operation of the power system. Since photovoltaic power generation is completely dependent on solar radiation, its output level fluctuates with changes in weather conditions (such as light intensity, cloud cover, temperature, etc.). This output is highly volatile, difficult to predict, and difficult to directly regulate, so that when photovoltaic power generation is incorporated into a large-scale power system, it will have a significant impact on the frequency stability of the power grid. Especially during periods of rapid changes in light conditions, such as sunrise and sunset, and rapid movement of clouds, the output of photovoltaic power generation may increase or decrease rapidly, resulting in large fluctuations in the frequency of the power grid, threatening the safe and stable operation of the power grid.

[0004] Traditionally, grid frequency regulation mainly relies on large units such as thermal power units and pumped storage units with large regulation capabilities. These units can quickly respond to changes in grid frequency by adjusting their output power, thereby maintaining grid frequency stability. However, with the continuous increase in the proportion of clean energy, the proportion of thermal power units and pumped storage units in the grid has gradually decreased, and their frequency regulation capabilities have also weakened accordingly. Therefore, how to effectively use renewable energy such as photovoltaics to regulate grid frequency has become an important issue that needs to be urgently solved for the stable operation of the current power grid.

[0005] In view of this, the present invention is proposed. Summary of the invention

[0006] The present invention provides a control method and system for a photovoltaic power generation system to participate in grid frequency regulation, which can be used not only to construct a "photovoltaic frequency regulation strategy without an energy storage system", but also to construct a "photovoltaic frequency regulation strategy with an energy storage system".

[0007] The technical solution of the present invention is:

[0008] According to a first aspect of the present invention, there is provided a control method for a photovoltaic power generation system to participate in grid frequency regulation, comprising the following steps: monitoring the frequency signal of the grid in real time by means of a frequency measuring device; recording the grid frequency deviation value when a deviation occurs between the monitored grid frequency and the rated frequency; determining the grid operating condition based on the recorded grid frequency deviation, and calculating the output power regulation amount of the photovoltaic power generation system using a preset frequency regulation control algorithm; judging whether the frequency regulation capability of the photovoltaic power generation system meets preset conditions based on the output capacity of the photovoltaic power generation system: if the preset conditions are met, the grid is frequency regulated only by the photovoltaic power generation system; otherwise, the photovoltaic power generation system is assisted by an energy storage system to participate in frequency regulation.

[0009] Furthermore, the operating condition of the power grid is determined based on the recorded power grid frequency deviation, and the power that the photovoltaic power generation system needs to provide or reduce is calculated using a preset frequency regulation control algorithm, specifically: based on the recorded power grid frequency deviation, the operating condition of the power grid is determined to be divided into a frequency reduction condition, a frequency unchanged condition, and a frequency increase condition; wherein, when the power grid frequency deviation is less than 0, the power grid is determined to be in a frequency reduction condition; when the power grid frequency deviation is equal to 0, the power grid is determined to be in a frequency unchanged condition; when the power grid frequency deviation is greater than 0, the power grid is determined to be in a frequency increase condition; the power grid is a power grid in which a photovoltaic power generation system, an energy storage system participates, or a power grid in which a photovoltaic power generation system participates; when the operating condition of the power grid is an increased frequency condition, the photovoltaic inverter reduces the output power of the photovoltaic power generation system to reduce the frequency of the power grid; when the operating condition of the power grid is a reduced frequency condition, the photovoltaic inverter increases the output power of the photovoltaic power generation system to increase the frequency of the power grid; wherein the photovoltaic inverter is an interface device between the photovoltaic power generation system and the power grid.

[0010] Furthermore, the photovoltaic power generation system is assisted by the energy storage system to participate in the frequency regulation. Specifically, after the photovoltaic power generation system participates in the frequency regulation, if the grid frequency is still in the frequency increase condition, the energy storage system is used to absorb excess electric energy; if the grid frequency is still in the frequency decrease condition, the energy storage system is used to release electric energy to supplement the shortage of the grid.

[0011] Furthermore, the frequency regulation control algorithm includes a proportional-integral-differential control algorithm, a fuzzy control algorithm and a neural network control algorithm.

[0012] According to a second aspect of the present invention, a control system for a photovoltaic power generation system to participate in grid frequency regulation is provided, comprising: a monitoring and recording module, for monitoring the frequency signal of the grid in real time through a frequency measuring device; when the monitored grid frequency deviates from the rated frequency, recording the grid frequency deviation value; a calculation module, for determining the working condition of the grid according to the recorded grid frequency deviation, and calculating the output power regulation amount of the photovoltaic power generation system by using a preset frequency regulation control algorithm; a frequency regulation module, for judging whether the frequency regulation capability of the photovoltaic power generation system meets the preset conditions according to the output capacity of the photovoltaic power generation system: if the preset conditions are met, the grid is frequency-regulated only by the photovoltaic power generation system; otherwise, the photovoltaic power generation system is assisted by the energy storage system to participate in the frequency regulation.

[0013] According to a third aspect of the present invention, a terminal is provided, comprising a processor, a memory, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of any one of the above methods when executing the computer program.

[0014] According to a fourth aspect of the present invention, a computer-readable storage medium is provided, on which a computer program is stored, and when the computer program is executed, the device where the computer-readable storage medium is located is controlled to execute the steps of any one of the above-mentioned methods.

[0015] The beneficial effects of the present invention are:

[0016] First, regardless of whether it is a PV frequency modulation scheme with or without an energy storage system, the PV inverter and energy storage system have extremely fast power response speed, which enables the PV power generation system to make rapid adjustments when the grid frequency deviates, effectively suppressing frequency fluctuations.

[0017] Second, the photovoltaic power generation system can still maintain a green and low-carbon power generation method while providing frequency regulation services; this helps reduce fossil fuel consumption and greenhouse gas emissions, and promotes the optimization of energy structure and sustainable development;

[0018] Third, the present invention uses advanced prediction algorithms and machine learning technology to make more accurate predictions of photovoltaic power generation output, and adjusts the output power of the photovoltaic power generation system in advance according to the prediction results to reduce the impact on the grid frequency. In addition, the photovoltaic power generation system can be adjusted in real time through intelligent control technology to better adapt to changes in grid frequency; this improves the operational stability and reliability of the grid and helps to ensure the safety and stability of power supply;

[0019] Fourth, compared with traditional frequency-modulation power plants, utilizing existing photovoltaic power generation facilities and energy storage systems to participate in grid frequency modulation can significantly reduce frequency modulation costs. This not only helps to improve the economic benefits of photovoltaic power generation systems, but also helps to promote the development and growth of the new energy industry.

[0020] In summary, with the rapid development of renewable energy, especially photovoltaic power generation, around the world, how to effectively use photovoltaic and other renewable energy to regulate grid frequency has become an important issue for the stable operation of the grid; and through continuous exploration and development of new control methods and systems, the grid-connected performance and frequency regulation capabilities of photovoltaic power generation can be further improved, providing strong support for building a safe, stable and efficient smart grid. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a method block diagram of the present invention;

[0022] Figure 2 It is a structural block diagram of the device of the present invention. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. It should be noted that the embodiments in this application and the features in the embodiments can be combined with each other arbitrarily without conflict.

[0024] Example 1: Figure 1 As shown, a control method for a photovoltaic power generation system to participate in grid frequency regulation is used to construct a photovoltaic frequency regulation strategy without an energy storage system, including the following steps:

[0025] The frequency signal of the power grid is monitored in real time by means of a frequency measuring device; when the monitored power grid frequency deviates from the rated frequency, the power grid frequency deviation value is recorded; specifically, when the power grid frequency deviates, the installed high-precision frequency measuring device will immediately record the amplitude and direction of the frequency deviation, the amplitude of the frequency deviation indicates the degree to which the power grid frequency deviates from the rated value, and the direction indicates whether the power grid frequency increases or decreases;

[0026] According to the recorded grid frequency deviation, the working condition of the grid is determined, and a preset frequency regulation control algorithm is used to calculate the output power regulation amount of the photovoltaic power generation system; the grid is frequency-regulated by the photovoltaic power generation system.

[0027] Furthermore, the operating condition of the power grid is determined based on the recorded power grid frequency deviation, and the power that the photovoltaic power generation system needs to provide or reduce is calculated using a preset frequency regulation control algorithm, specifically: based on the recorded power grid frequency deviation, the operating condition of the power grid is determined to be divided into a frequency reduction condition, a frequency unchanged condition, and a frequency increase condition; wherein, when the power grid frequency deviation is less than 0, the power grid is determined to be in a frequency reduction condition; when the power grid frequency deviation is equal to 0, the power grid is determined to be in a frequency unchanged condition; when the power grid frequency deviation is greater than 0, the power grid is determined to be in a frequency increase condition; the power grid is a power grid without an energy storage system and with the participation of a photovoltaic power generation system; when the operating condition of the power grid is an increased frequency condition, the photovoltaic inverter reduces the output power of the photovoltaic power generation system to reduce the frequency of the power grid; when the operating condition of the power grid is a reduced frequency condition, the photovoltaic inverter increases the output power of the photovoltaic power generation system to increase the frequency of the power grid; wherein the photovoltaic inverter is an interface device between the photovoltaic power generation system and the power grid.

[0028] It should be noted that the communication module is a bridge between the photovoltaic power generation system and the power grid dispatching center; this module realizes data interaction between the photovoltaic power generation system and the power grid dispatching center to ensure the real-time transmission of dispatching instructions. The communication module usually adopts high-speed and reliable communication protocols and technologies, such as Ethernet, fiber-optic communication or wireless communication. Through these communication means, the photovoltaic power generation system can send operating data (such as power generation, power factor, voltage and current, etc.) and status information (such as fault alarm, equipment status, etc.) to the power grid dispatching center in real time. At the same time, the power grid dispatching center can also send dispatching instructions to the photovoltaic power generation system, such as power regulation instructions, voltage regulation instructions, etc. The reliability and real-time performance of the communication module are crucial to the safe and stable operation of the photovoltaic power generation system and the dispatching management of the power grid. Therefore, when selecting communication equipment and protocols, it is necessary to pay attention to indicators such as communication rate, bit error rate, anti-interference ability and security.

[0029] Furthermore, the frequency regulation control algorithm includes a proportional-integral-differential (PID) control algorithm, a fuzzy control algorithm, and a neural network control algorithm. The PID control algorithm is a classic control method that can achieve precise regulation of the grid frequency deviation by adjusting the parameters of the three links of proportional, integral, and differential. The fuzzy control algorithm uses fuzzy logic to handle the complex relationship between the grid frequency deviation and the output power of the photovoltaic power generation system, thereby achieving more intelligent regulation. The neural network control algorithm predicts the changing trend of the grid frequency by training a neural network model, and adjusts the output power of the photovoltaic power generation system accordingly.

[0030] Furthermore, in addition to participating in frequency modulation, the photovoltaic power generation system also has a voltage support function. When the grid voltage fluctuates, the photovoltaic power generation system can maintain the stability of the grid voltage by adjusting the reactive power. This function is mainly achieved through the reactive power control of the photovoltaic inverter. The photovoltaic inverter can not only control the output of active power, but also adjust the output of reactive power. When the grid voltage increases, the photovoltaic inverter can reduce the output of reactive power to reduce the voltage of the grid. Conversely, when the grid voltage decreases, the photovoltaic inverter can increase the output of reactive power to increase the voltage of the grid. This voltage support function can further improve the stability and reliability of the grid.

[0031] Although the photovoltaic power generation system has a certain frequency regulation capability, in some cases (such as drastic changes in light conditions, large fluctuations in grid load, etc.), the photovoltaic power generation system may not be able to respond quickly to frequency regulation needs; the energy storage system has the characteristics of rapid response and flexible regulation, and can provide or absorb a large amount of electrical energy in a short period of time; when the photovoltaic power generation system cannot meet the frequency regulation needs of the grid, the energy storage system can quickly intervene to balance the frequency fluctuations of the grid through charging and discharging; this energy storage-assisted frequency regulation method can further improve the frequency stability of the grid. The following optional implementation examples are given for the grid in which the energy storage system and the photovoltaic power generation system participate:

[0032] Example 2: Figure 1 As shown, a control method for a photovoltaic power generation system to participate in grid frequency regulation is used to construct a photovoltaic frequency regulation strategy configured with an energy storage system, including the following steps: real-time monitoring of the frequency signal of the grid by a frequency measuring device; when a deviation occurs between the monitored grid frequency and the rated frequency, recording the grid frequency deviation value; determining the grid operating condition based on the recorded grid frequency deviation, and calculating the output power regulation amount of the photovoltaic power generation system by using a preset frequency regulation control algorithm; and assisting the photovoltaic power generation system in participating in frequency regulation by using an energy storage system.

[0033] Furthermore, the operating condition of the power grid is determined based on the recorded power grid frequency deviation, and the power that the photovoltaic power generation system needs to provide or reduce is calculated using a preset frequency regulation control algorithm, specifically: based on the recorded power grid frequency deviation, the operating condition of the power grid is determined to be divided into a frequency reduction condition, a frequency unchanged condition, and a frequency increase condition; wherein, when the power grid frequency deviation is less than 0, the power grid is determined to be in a frequency reduction condition; when the power grid frequency deviation is equal to 0, the power grid is determined to be in a frequency unchanged condition; when the power grid frequency deviation is greater than 0, the power grid is determined to be in a frequency increase condition; the power grid is a power grid in which an energy storage system and a photovoltaic power generation system participate; when the operating condition of the power grid is an increased frequency condition, the photovoltaic inverter reduces the output power of the photovoltaic power generation system to reduce the frequency of the power grid; when the operating condition of the power grid is a reduced frequency condition, the photovoltaic inverter increases the output power of the photovoltaic power generation system to increase the frequency of the power grid; wherein the photovoltaic inverter is an interface device between the photovoltaic power generation system and the power grid.

[0034] Furthermore, the photovoltaic power generation system is assisted by the energy storage system to participate in the frequency modulation, specifically: after the photovoltaic power generation system participates in the frequency modulation, if the grid frequency is still in the frequency increase condition, the energy storage system is used to absorb excess electric energy; if the grid frequency is still in the frequency decrease condition, the energy storage system is used to release electric energy to supplement the shortage of the grid. It should be noted that the energy storage system is an important auxiliary means for the photovoltaic power generation system to participate in the grid frequency modulation. The system includes a battery energy storage device and a control system, which can quickly respond to changes in the grid frequency and assist the photovoltaic system in frequency modulation. The battery energy storage device is usually composed of multiple battery cells and can store a large amount of electric energy. When the grid frequency fluctuates, the energy storage device can quickly intervene to balance the frequency fluctuation of the grid through charging and discharging. For example, when the grid frequency rises, the energy storage device can absorb excess electric energy; when the grid frequency drops, the energy storage device can release electric energy to supplement the shortage of the grid. The control system of the energy storage module is responsible for monitoring the grid frequency and the charging and discharging status of the energy storage device, and controlling the energy storage device in real time according to the frequency modulation requirements. Through a reasonable charging and discharging strategy, the frequency modulation effect and economy of the energy storage device can be maximized.

[0035] Furthermore, the frequency regulation control algorithm includes a proportional-integral-differential (PID) control algorithm, a fuzzy control algorithm, and a neural network control algorithm. The PID control algorithm is a classic control method that can achieve precise regulation of the grid frequency deviation by adjusting the parameters of the three links of proportional, integral, and differential. The fuzzy control algorithm uses fuzzy logic to handle the complex relationship between the grid frequency deviation and the output power of the photovoltaic power generation system, thereby achieving more intelligent regulation. The neural network control algorithm predicts the changing trend of the grid frequency by training a neural network model, and adjusts the output power of the photovoltaic power generation system accordingly.

[0036] Furthermore, in addition to participating in frequency regulation, photovoltaic power generation systems also have a voltage support function.

[0037] According to the technical solutions shown in the above two embodiments, it can be known that the present invention can be used to construct "photovoltaic frequency modulation strategy without energy storage system" and "photovoltaic frequency modulation strategy with energy storage system", wherein the photovoltaic frequency modulation strategy without energy storage system refers to that when the energy storage system is not configured, the photovoltaic power generation system mainly relies on the active power regulation function of its inverter to participate in the grid frequency modulation; the photovoltaic frequency modulation strategy with energy storage system refers to the energy storage system assisting the photovoltaic power generation system to participate in the frequency modulation. 1) For the photovoltaic frequency modulation scheme without energy storage system: On the one hand, it is mainly applicable to the frequency modulation requirements under the light load state of the grid; when the grid load is light, the frequency fluctuation is relatively small, and the photovoltaic power generation system can meet the frequency modulation requirements through the power regulation function of the inverter. In addition, since there is no need to configure an energy storage device, this scheme has certain advantages in cost. On the second hand: since the power response speed of the photovoltaic inverter is fast, the response time of this scheme is usually about a few seconds. Although this is slightly longer than the scheme with energy storage system, it is sufficient to meet the frequency modulation requirements of the grid under light load. 2) When equipped with energy storage devices, the photovoltaic power generation system and the energy storage system work together to participate in the grid frequency regulation. The specific characteristics of this frequency regulation method are as follows: First, this frequency regulation method can more effectively balance the grid frequency, especially under conditions where the frequency fluctuations are large. The photovoltaic frequency regulation scheme equipped with an energy storage system is suitable for conditions where the grid frequency fluctuates greatly. For example, in areas where the grid load is heavy or the proportion of renewable energy power generation is high, frequency fluctuations may be more frequent and severe. At this time, the rapid response capability of the energy storage system can significantly improve the frequency regulation effect and ensure the stable operation of the grid. Second, because the energy storage system has an extremely fast power response speed (usually up to milliseconds), the response time of this scheme is very short. This enables the photovoltaic power generation system to respond quickly when the grid frequency changes suddenly, effectively suppressing frequency fluctuations. In summary, whether it is a photovoltaic frequency modulation scheme with or without energy storage system, the photovoltaic inverter and energy storage system have extremely fast power response speed, which enables the photovoltaic power generation system to make rapid adjustments when the grid frequency deviates, effectively suppressing frequency fluctuations; while providing frequency modulation services, the photovoltaic power generation system can still maintain a green and low-carbon power generation method; this helps to reduce the consumption of fossil fuels and greenhouse gas emissions, and promote the optimization and sustainable development of the energy structure; through intelligent frequency modulation control algorithms (such as PID control algorithms, fuzzy control algorithms, etc.), the photovoltaic power generation system can flexibly respond to changes in grid frequency. This improves the operational stability and reliability of the power grid and helps to ensure the safety and stability of power supply; compared with traditional frequency modulation power plants, the use of existing photovoltaic power generation facilities and energy storage systems to participate in grid frequency modulation can significantly reduce the frequency modulation cost, which not only helps to improve the economic benefits of photovoltaic power generation systems, but also helps to promote the development and growth of new energy industries.

[0038] Example 3: Figure 2As shown, a control system for a photovoltaic power generation system to participate in grid frequency modulation includes: a monitoring and recording module 101, which is used to monitor the frequency signal of the grid in real time through a frequency measuring device; when the monitored grid frequency deviates from the rated frequency, the grid frequency deviation value is recorded; a calculation module 102, which is used to determine the working condition of the grid according to the recorded grid frequency deviation, and calculate the output power adjustment amount of the photovoltaic power generation system using a preset frequency regulation control algorithm; a frequency modulation module 103, which determines whether the frequency modulation capacity of the photovoltaic power generation system meets the preset conditions according to the output capacity of the photovoltaic power generation system: if the preset conditions are met, the grid is frequency modulated only by the photovoltaic power generation system; otherwise, the photovoltaic power generation system is assisted by the energy storage system to participate in the frequency modulation. The term "module" as used above can be a combination of software and / or hardware that implements a predetermined function. Although the system described in the above embodiment is preferably implemented in software, the implementation of hardware, or a combination of software and hardware, is also possible and conceived. For parts that are not described in detail in each module, please refer to the relevant description of other embodiments above.

[0039] Embodiment 4: A terminal comprises a processor, a memory, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the method described in the above embodiment when executing the computer program.

[0040] In an exemplary embodiment, the terminal may further include a transmission device and an input / output device, wherein the transmission device is connected to the processor, and the input / output device is connected to the processor.

[0041] Embodiment 5: A computer-readable storage medium stores a computer program, which controls a device where the computer-readable storage medium is located to execute the steps of the method described in the above embodiment when the computer program is running.

[0042] In an exemplary embodiment, the computer-readable storage medium may include, but is not limited to, various media that can store computer programs, such as a USB flash drive, a read-only memory (ROM), a random access memory (RAM), a mobile hard disk, a magnetic disk or an optical disk.

[0043] Obviously, those skilled in the art should understand that the above modules or steps of the present invention can be implemented by a general computing device, they can be concentrated on a single computing device, or distributed on a network composed of multiple computing devices, they can be implemented by a program code executable by a computing device, so that they can be stored in a storage device and executed by the computing device, and in some cases, the steps shown or described can be executed in a different order than here, or they can be made into individual integrated circuit modules, or multiple modules or steps therein can be made into a single integrated circuit module for implementation. Thus, the present invention is not limited to any specific combination of hardware and software.

[0044] The specific implementation modes of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above implementation modes, and various changes can be made within the knowledge scope of ordinary technicians in this field without departing from the purpose of the present invention.

Claims

1. A control method for a photovoltaic power generation system to participate in power grid frequency modulation, characterized in that: The following steps are involved: The frequency signal of the power grid is monitored in real time through the frequency measuring device; when the monitored power grid frequency deviates from the rated frequency, the power grid frequency deviation value is recorded; According to the recorded grid frequency deviation, the grid operating condition is determined, and the output power regulation of the photovoltaic power generation system is calculated using a preset frequency regulation control algorithm; Whether the frequency regulation capability of the photovoltaic power generation system meets the preset conditions is determined based on the output capacity of the photovoltaic power generation system: if the preset conditions are met, the frequency of the power grid is regulated only by the photovoltaic power generation system; otherwise, the photovoltaic power generation system is assisted by the energy storage system to participate in the frequency regulation.

2. The control method for photovoltaic power generation system participating in grid frequency modulation according to claim 1, characterized in that: The operating condition of the power grid is determined based on the recorded power grid frequency deviation, and the power that the photovoltaic power generation system needs to provide or reduce is calculated using a preset frequency regulation control algorithm, specifically: According to the recorded grid frequency deviation, the grid operating condition is determined to be a frequency reduction condition, a frequency unchanged condition, and a frequency increase condition; wherein, when the grid frequency deviation is less than 0, the grid is determined to be in a frequency reduction condition; when the grid frequency deviation is equal to 0, the grid is determined to be in a frequency unchanged condition; when the grid frequency deviation is greater than 0, the grid is determined to be in a frequency increase condition; the grid is a grid in which a photovoltaic power generation system, an energy storage system participates, or a grid in which a photovoltaic power generation system participates; When the operating condition of the power grid is an increased frequency condition, the photovoltaic inverter reduces the output power of the photovoltaic power generation system to reduce the frequency of the power grid; when the operating condition of the power grid is a reduced frequency condition, the photovoltaic inverter increases the output power of the photovoltaic power generation system to increase the frequency of the power grid; among them, the photovoltaic inverter is the interface device between the photovoltaic power generation system and the power grid.

3. The control method for photovoltaic power generation system participating in grid frequency modulation according to claim 1, characterized in that: The method of assisting the photovoltaic power generation system with the energy storage system to participate in frequency regulation is as follows: after the photovoltaic power generation system participates in frequency regulation, if the grid frequency is still in an increasing frequency condition, the energy storage system is used to absorb excess electric energy; if the grid frequency is still in a decreasing frequency condition, the energy storage system is used to release electric energy to supplement the shortage of the grid.

4. The control method for photovoltaic power generation system participating in grid frequency modulation according to claim 1, characterized in that: The frequency regulation control algorithm includes a proportional-integral-differential control algorithm, a fuzzy control algorithm and a neural network control algorithm.

5. A control system for a photovoltaic power generation system to participate in power grid frequency modulation, characterized in that: include: The monitoring and recording module is used to monitor the frequency signal of the power grid in real time through the frequency measuring device; when the monitored power grid frequency deviates from the rated frequency, the power grid frequency deviation value is recorded; A calculation module is used to determine the working condition of the power grid according to the recorded power grid frequency deviation, and calculate the output power adjustment amount of the photovoltaic power generation system using a preset frequency adjustment control algorithm; The frequency modulation module determines whether the frequency modulation capability of the photovoltaic power generation system meets the preset conditions according to the output capacity of the photovoltaic power generation system: if the preset conditions are met, the frequency of the power grid is modulated only by the photovoltaic power generation system; otherwise, the photovoltaic power generation system is assisted by the energy storage system to participate in the frequency modulation.

6. A terminal comprising a processor, a memory, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 4 are implemented.

7. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is running, the device where the computer-readable storage medium is located is controlled to execute the steps of the method according to any one of claims 1 to 4.

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