Fault voltage control method and device of power generation system, medium and equipment

Abstract

The invention discloses a fault voltage control method and device of a power generation system, a medium and equipment. A fault signal of a power grid system is received; controlling a grid-side converter to generate reactive power according to the fault signal, and controlling a rotor-side converter to generate a rotor current signal; acquiring an electric signal output by the photovoltaic array; and finally, controlling a DC-DC converter according to the reactive power, the rotor current state signal and the electric signal, so that the DC-DC converter adjusts the output of the photovoltaic array and the doubly-fed fan. According to the invention, rapid response and effective management of the power grid fault are realized, so that the problem that the fault voltage of the wind power photovoltaic system cannot be efficiently controlled in the prior art is solved.

Description

Technical Field

[0001] The present invention relates to the field of fault voltage control of power generation systems, and in particular to a method, device, medium and equipment for fault voltage control of power generation systems. Background Art

[0002] With the growth of global energy demand and the improvement of environmental protection awareness, renewable energy technology has developed rapidly. As two major renewable energy sources, wind power and solar power have attracted widespread attention due to their clean and renewable characteristics. However, wind and solar power generation systems pose challenges to the stable operation of the power grid due to the instability of their natural energy. With the rapid development of renewable energy technology, the penetration rate of wind and solar power generation systems in the power grid continues to increase. These systems usually need to have fault ride-through capabilities (FRT) to maintain stable operation when a fault occurs in the power grid and avoid causing additional pressure on the power grid.

[0003] However, existing technologies are insufficient in efficiently controlling the fault voltage of wind photovoltaic systems, which is mainly manifested in serious challenges to stable and efficient operation under weak or very weak grid conditions. Traditional current source mode control strategies can ensure system stability and rapid power control under strong grid conditions, but under weak grid conditions, especially in scenarios where a high proportion of renewable energy power generation units are connected to the grid, it has many limitations in stability, system voltage and frequency adjustment, and is difficult to adapt to. These problems make it impossible for existing technologies to efficiently control the fault voltage of wind photovoltaic systems. Summary of the invention

[0004] The present invention provides a method, device, medium and equipment for controlling a fault voltage of a power generation system, so as to solve the problem that the prior art cannot efficiently control the fault voltage of a wind photovoltaic system.

[0005] In a first aspect, the present application provides a fault voltage control method for a power generation system, comprising:

[0006] Receive fault signals from the power grid system;

[0007] According to the fault signal, controlling the grid-side converter to generate reactive power, and controlling the rotor-side converter to generate a rotor current signal;

[0008] Acquiring an electrical signal output by a photovoltaic array;

[0009] The DC-DC converter is controlled according to the reactive power, the rotor current state signal and the electrical signal, so that the DC-DC converter adjusts the output of the photovoltaic array and the double-fed wind turbine.

[0010] The present application realizes rapid response and effective management of power grid faults by integrating the coordinated work of current limiting devices, grid-side converters, rotor-side converters, DC-DC converters and photovoltaic arrays. First, as a monitoring point of the power grid status, the current limiting device can capture the fault signals of the power grid in time and quickly transmit these signals to the grid-side converter and the rotor-side converter, ensuring that the system is instantly aware of the abnormality of the power grid. The grid-side converter generates reactive power according to the fault signal to support the stability of the power grid, and sends a reactive power generation signal to the DC-DC converter, which helps the system adjust the energy output at the overall level. The rotor-side converter controls the rotor current of the doubly fed wind turbine according to the fault signal, and sends a rotor current state signal to the DC-DC converter to ensure the stable operation of the wind power generation part. The photovoltaic array sends an electrical signal to the DC-DC converter, so that the system can adjust the energy flow according to the real-time output of photovoltaic power generation. The DC-DC converter integrates the reactive power generation signal, the rotor current state signal and the electrical signal of the photovoltaic array, dynamically adjusts the energy flow between the photovoltaic array and the DC link of the doubly fed wind turbine, and maintains the energy balance of the system. Combining these measures, the present application not only improves the adaptability and stability of the power generation system to grid faults, but also optimizes energy management, reduces the impact on the grid, and improves the reliability and stability of the entire power system, thereby solving the problem that the existing technology cannot efficiently control the fault voltage of the wind photovoltaic system.

[0011] As a preferred embodiment of the first aspect, the fault voltage control method of the power generation system is applicable to a power generation system, wherein the power generation system includes: a photovoltaic array, a doubly-fed wind turbine, a DC-DC converter, a grid-side converter, a rotor-side converter and a current limiting device, specifically:

[0012] The current limiting device is connected to the power grid, and is connected to the grid-side converter and the double-fed wind turbine;

[0013] The grid-side converter is connected to the DC-DC converter;

[0014] The rotor-side converter is connected to the doubly-fed wind turbine and to the DC-DC converter;

[0015] The DC-DC converter is connected to the photovoltaic array.

[0016] In this preferred embodiment, the component connection and signal transmission mechanism designed by the present application realizes efficient response and energy management to power grid faults. First, the current limiting device is directly connected to the power grid, and is connected to the grid-side converter and the doubly fed wind turbine. This layout enables the system to quickly sense the abnormal state of the power grid and transmit the fault signal to the key components in a timely manner. The connection between the grid-side converter and the DC-DC converter enables the generation and regulation of reactive power to quickly respond to the needs of the power grid, while the rotor-side converter is connected to the doubly fed wind turbine and the DC-DC converter at the same time, ensuring the precise control of the rotor current of the doubly fed wind turbine and timely adjusting the energy flow between the photovoltaic array and the DC link of the doubly fed wind turbine. This connection mode, combined with the direct connection of the DC-DC converter to the photovoltaic array, allows the system to quickly redistribute and balance the energy output of photovoltaic and wind power generation when a fault occurs, and maintain the energy balance of the system. Therefore, the present application can improve the adaptability of the power generation system to power grid faults, optimize energy distribution, reduce the impact of power grid faults on the system, thereby enhancing the stability and reliability of the entire power supply system. Through this structured and efficient component connection, the system is able to maintain stable operation, reduce voltage fluctuations and improve the resilience of the grid when a grid failure occurs, which is of great significance for improving the grid compatibility of renewable energy power generation systems and the security of overall power supply.

[0017] As a preferred embodiment of the first aspect, controlling the grid-side converter to generate reactive power according to the fault signal is specifically:

[0018] According to the fault signal, the PI controller and the first preset power value, the grid-side converter is controlled to generate reactive power.

[0019] In this preferred embodiment, the present application controls the grid-side converter to generate reactive power by combining a fault signal, a PI controller and a first preset power value, which can effectively improve the responsiveness and stability of the power generation system in the face of a grid fault. First, the real-time monitoring of the fault signal enables the system to quickly identify the abnormal state of the grid, providing the necessary premise for subsequent control actions. Then, the PI controller dynamically adjusts its output according to this signal and the preset reactive power value to accurately control the behavior of the grid-side converter. The proportional part of the PI controller can quickly respond to immediate changes in the state of the grid, while the integral part can eliminate long-term errors and ensure the stable output of reactive power. This control strategy can not only respond quickly to grid faults, but also maintain the stability of the grid voltage and frequency during faults, reducing the impact on the grid.

[0020] As a preferred embodiment of the first aspect, the controlling the rotor-side converter to generate a rotor current signal according to the fault signal is specifically:

[0021] Obtaining a three-phase voltage signal according to the fault signal, the second preset power value and the PI controller;

[0022] According to the three-phase voltage signal, the rotor-side converter is controlled to generate a rotor current signal.

[0023] In this preferred embodiment, the present application controls the rotor-side converter to generate a rotor current signal by combining a fault signal, a second preset power value and a PI controller, which can effectively improve the performance and stability of the wind photovoltaic power generation system in the event of a power grid failure. First, real-time monitoring of the fault signal enables the system to quickly identify abnormal conditions of the power grid, which is the key first step to ensure timely response of the system. Next, the PI controller dynamically adjusts its output according to the fault signal and the second preset power value, wherein the proportional part can quickly respond to immediate changes in the power grid state, while the integral part can eliminate long-term errors and ensure stable output of the rotor current. This control strategy can not only respond quickly to power grid failures, but also maintain the stability of the power grid voltage and frequency during the fault, reducing the impact on the power grid.

[0024] As a preferred embodiment of the first aspect, after controlling the rotor-side converter to generate a rotor current signal according to the fault signal, the method further includes:

[0025] When the rotor current exceeds a preset threshold, the double-fed wind turbine is controlled to be disconnected from the power grid system.

[0026] In this preferred embodiment, when the rotor current exceeds the preset threshold, the system will control the double-fed wind turbine to disconnect from the grid, avoiding equipment damage and further grid instability caused by overcurrent. This design not only protects the power generation equipment from damage, but also reduces the impact of grid failure on the entire power system, improving the reliability and safety of the system.

[0027] As a preferred embodiment of the first aspect, the acquiring of the electrical signal output by the photovoltaic array is specifically:

[0028] According to the maximum power point tracking algorithm, the maximum power of the photovoltaic array is controlled to be extracted, so that the photovoltaic array outputs an electrical signal according to the maximum power.

[0029] In this preferred embodiment, the present application can significantly improve the efficiency and energy output of the photovoltaic power generation system by using the maximum power point tracking (MPPT) algorithm to control the method of outputting electrical signals from the photovoltaic array. The core of the MPPT algorithm is to dynamically adjust the working state of the photovoltaic array so as to always track and output the maximum power point. This real-time optimization process enables the photovoltaic array to remain in the best working state under different environmental conditions, such as when the light intensity and temperature change. Therefore, the photovoltaic array can more effectively convert solar energy into electrical energy, improving the efficiency of energy capture and conversion. This efficiency improvement directly leads to an increase in the overall output electrical signal of the system, thereby providing more clean energy for the power grid. The present application can optimize the performance of the photovoltaic array and improve the efficiency and reliability of solar power generation through precise energy management.

[0030] As a preferred embodiment of the first aspect, the receiving a fault signal of the power grid system specifically comprises:

[0031] The current limiting device is controlled to detect a fault signal of the power grid system to obtain a fault signal.

[0032] In a second aspect, the present application provides a fault voltage control device for a power generation system, the fault voltage control device for the power generation system comprising a receiving module, a control module, an acquisition module and an adjustment module;

[0033] The receiving module is used to receive the fault signal of the power grid system;

[0034] The control module is used to control the grid-side converter to generate reactive power and control the rotor-side converter to generate a rotor current signal according to the fault signal;

[0035] The acquisition module is used to acquire the electrical signal output by the photovoltaic array;

[0036] The adjustment module is used to control the DC-DC converter according to the reactive power, the rotor current state signal and the electrical signal, so that the DC-DC converter adjusts the output of the photovoltaic array and the double-fed wind turbine.

[0037] This device uses four modules to divide the work and coordinate work to better control the fault voltage. This application realizes rapid response and effective management of power grid faults by integrating the current limiting device, grid-side converter, rotor-side converter, DC-DC converter and photovoltaic array. First, as a monitoring point of the power grid status, the current limiting device can capture the fault signal of the power grid in time and quickly transmit these signals to the grid-side converter and the rotor-side converter, ensuring the system's instant perception of power grid abnormalities. The grid-side converter generates reactive power according to the fault signal to support the stability of the power grid, and sends a reactive power generation signal to the DC-DC converter, which helps the system adjust the energy output at the overall level. The rotor-side converter controls the rotor current of the doubly fed wind turbine according to the fault signal, and sends a rotor current state signal to the DC-DC converter to ensure the stable operation of the wind power generation part. The photovoltaic array sends an electrical signal to the DC-DC converter, so that the system can adjust the energy flow according to the real-time output of photovoltaic power generation. The DC-DC converter integrates the reactive power generation signal, the rotor current state signal and the electrical signal of the photovoltaic array, dynamically adjusts the energy flow between the photovoltaic array and the DC link of the doubly fed wind turbine, and maintains the energy balance of the system. Combining these measures, this application not only improves the adaptability and stability of the power generation system to grid failures, but also optimizes energy management, reduces the impact on the grid, and improves the reliability and stability of the entire power system. This solves the problem that the existing technology cannot efficiently control the fault voltage of the wind photovoltaic system.

[0038] In a third aspect, the present application provides a computer-readable storage medium, the computer-readable storage medium including a stored computer program, wherein when the computer program is executed, the device where the computer-readable storage medium is located is controlled to execute a fault voltage control method for a power generation system as described. Its beneficial effects are the same as those of the fault voltage control method for a power generation system provided in the first aspect of the present application.

[0039] In a fourth aspect, the present application provides a terminal device, comprising a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, wherein when the processor executes the computer program, it implements any one of the fault voltage control methods for a power generation system as described in the first aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 : A flow chart of an embodiment of a fault voltage control method for a power generation system provided by the present application;

[0041] Figure 2 : A structural schematic diagram of an embodiment of a hybrid wind power / photovoltaic power generation system provided in the present application;

[0042] Figure 3: A flow chart of an embodiment of power grid fault control provided by the present application;

[0043] Figure 4 : A structural schematic diagram of an embodiment of a fault voltage control device for a power generation system provided in the present application. DETAILED DESCRIPTION

[0044] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0045] Embodiment 1

[0046] Please refer to Figure 1 , which is a fault voltage control method for a power generation system provided by an embodiment of the present invention.

[0047] In this embodiment, the process of the fault voltage control method of the power generation system in this application is described in detail through steps S01-S04.

[0048] The fault voltage control method of the power generation system of the present application is applicable to the power generation system, which includes: a photovoltaic array, a double-fed wind turbine, a DC-DC converter, a grid-side converter, a rotor-side converter and a current limiting device, such as Figure 2 As shown, specifically:

[0049] The current limiting device is connected to the power grid, and is connected to the grid-side converter and the double-fed wind turbine;

[0050] The grid-side converter is connected to the DC-DC converter;

[0051] The rotor-side converter is connected to the doubly-fed wind turbine and to the DC-DC converter;

[0052] The DC-DC converter is connected to the photovoltaic array.

[0053] S01: Receive a fault signal from the power grid system.

[0054] More specifically, the fault signal is obtained by controlling a current limiting device so that the current limiting device detects an abnormal signal in the power grid system.

[0055] S02: According to the fault signal, control the grid-side converter to generate reactive power, and control the rotor-side converter to generate a rotor current signal.

[0056] As a preferred embodiment of the first embodiment, controlling the grid-side converter to generate reactive power according to the fault signal is specifically:

[0057] Controlling the grid-side converter to generate reactive power according to the fault signal, the PI controller and the first preset power value;

[0058] More specifically, the PI controller is:

[0059] Fuzzy PI control is an advanced control strategy that combines traditional proportional integral (PI) control with fuzzy logic to deal with uncertainty and nonlinearity. Fuzzy PI control dynamically adjusts two key parameters of the PI controller by introducing fuzzy logic: proportional gain (Kp) and integral gain (Ki). This method is particularly suitable for systems where it is difficult to establish an accurate mathematical model, or when system parameters and environmental conditions change over time. The fuzzy logic controller is the core of fuzzy PI control, which uses fuzzy set theory to deal with input uncertainty and ambiguity. FLC usually includes the following four main parts:

[0060] (1) Fuzzification: Converting precise input data into fuzzy values. This usually involves defining a fuzzy set and the corresponding membership function.

[0061] (2) Rule Evaluation: Process the fuzzified input according to the defined fuzzy rules. These rules are usually if-then statements based on expert knowledge or experience.

[0062] (3) Decision Making: Evaluate the results of fuzzy rules by applying certain logical operations (such as maximum-minimum synthesis) and generate output fuzzy sets.

[0063] (4) Defuzzification: Convert fuzzy output into precise control value.

[0064] In a fuzzy PI control system, the Kp and Ki parameters of the PI controller are dynamically adjusted based on the real-time performance of the system. The adjustment process usually follows these steps:

[0065] (1) Error and change in error are used as inputs to the FLC. These inputs reflect the current state and trend of the system.

[0066] (2) The FLC processes these inputs according to preset rules to determine the adjustment values ​​for Kp and Ki. For example, if the error is large and the error changes quickly, the FLC may decide to increase Kp to respond quickly.

[0067] (3) The adjusted Kp and Ki are used to update the PI controller, thereby optimizing the control effect in real time.

[0068] When implementing fuzzy PI control, the following steps are required:

[0069] (1) System modeling and analysis: Determine the dynamic characteristics and control requirements of the system.

[0070] (2) Design FLC: define input and output variables, membership functions, fuzzy rules and defuzzification methods.

[0071] (3) Integrated PI controller: Integrate the FLC with the PI controller to ensure dynamic adjustment of Kp and Ki.

[0072] (4) Simulation and testing: Test the control system under different conditions to verify its performance and stability.

[0073] (5) Adjustment and optimization: Adjust the fuzzy rules and controller parameters according to the test results to optimize the system performance.

[0074] In this preferred embodiment, the present application controls the grid-side converter to generate reactive power by combining a fault signal, a PI controller and a first preset power value, which can effectively improve the responsiveness and stability of the power generation system in the face of a grid fault. First, the real-time monitoring of the fault signal enables the system to quickly identify the abnormal state of the grid, providing the necessary premise for subsequent control actions. Then, the PI controller dynamically adjusts its output according to this signal and the preset reactive power value to accurately control the behavior of the grid-side converter. The proportional part of the PI controller can quickly respond to immediate changes in the state of the grid, while the integral part can eliminate long-term errors and ensure the stable output of reactive power. This control strategy can not only respond quickly to grid faults, but also maintain the stability of the grid voltage and frequency during faults, reducing the impact on the grid.

[0075] As a preferred embodiment of the first embodiment, the step of controlling the rotor-side converter to generate a rotor current signal according to the fault signal is specifically as follows:

[0076] Obtaining a three-phase voltage signal according to the fault signal, the second preset power value and the PI controller;

[0077] According to the three-phase voltage signal, the rotor-side converter is controlled to generate a rotor current signal.

[0078] In this preferred embodiment, the present application controls the rotor-side converter to generate a rotor current signal by combining a fault signal, a second preset power value and a PI controller, which can effectively improve the performance and stability of the wind photovoltaic power generation system in the event of a power grid failure. First, real-time monitoring of the fault signal enables the system to quickly identify abnormal conditions of the power grid, which is the key first step to ensure timely response of the system. Next, the PI controller dynamically adjusts its output according to the fault signal and the second preset power value, wherein the proportional part can quickly respond to immediate changes in the power grid state, while the integral part can eliminate long-term errors and ensure stable output of the rotor current. This control strategy can not only respond quickly to power grid failures, but also maintain the stability of the power grid voltage and frequency during the fault, reducing the impact on the power grid.

[0079] As a preferred embodiment of the first embodiment, after controlling the rotor-side converter to generate a rotor current signal according to the fault signal, the method further includes:

[0080] When the rotor current exceeds a preset threshold, the double-fed wind turbine is controlled to be disconnected from the power grid system.

[0081] In this preferred embodiment, when the rotor current exceeds the preset threshold, the system will control the double-fed wind turbine to disconnect from the grid, avoiding equipment damage and further grid instability caused by overcurrent. This design not only protects the power generation equipment from damage, but also reduces the impact of grid failure on the entire power system, improving the reliability and safety of the system.

[0082] S03: Acquire the electrical signal output by the photovoltaic array.

[0083] As a preferred embodiment of the first embodiment, the step of acquiring the electrical signal output by the photovoltaic array is specifically:

[0084] According to the maximum power point tracking algorithm, the maximum power of the photovoltaic array is controlled to be extracted, so that the photovoltaic array outputs an electrical signal according to the maximum power.

[0085] The maximum power point tracking algorithm is specifically:

[0086] By adjusting the array terminal voltage reference from V1 to V2, the output power increment dP=P2-P1 is positive, so the algorithm should continue to increase the terminal voltage to V3. When the voltage increases from V2 to V3, the output power increment dP=P3-P2 is positive, so the algorithm increases the terminal voltage from V3 to V4. At this time, the output power difference (dP=P4-P3) is negative, and the terminal reference voltage moves in the opposite direction. The terminal voltage should return from V4 to V3. This means that the power of the PV will continue to fluctuate before approaching the maximum power point (MPP). The goal of the MPPT algorithm is to find the point where the dP / dV value becomes zero. When dP / dV is positive, the terminal voltage of the PV array should be increased; conversely, if dP / dV is negative, the terminal voltage should be reduced. Therefore, dP / dV can be derived from voltage and current:

[0087]

[0088] Let dP / dV=0.0, we can get the following formula:

[0089]

[0090] But the above method fails when the sampled voltage does not vary from one sample to another, the above equation results in division by zero, so multiplying both sides of the equation by dV gives the following formula:

[0091] dP=V·dI+I·dV;

[0092] dP=V·dI;

[0093] Regardless of whether V is a positive number or a constant, an increase in output power P is accompanied by an increase in output current. Similarly, a decrease in output power P is accompanied by a decrease in output current. This implementation makes it possible to track the maximum power point even when the sampling terminal voltage is constant.

[0094] In this preferred embodiment, the present application can significantly improve the efficiency and energy output of the photovoltaic power generation system by using the maximum power point tracking (MPPT) algorithm to control the method of outputting electrical signals from the photovoltaic array. The core of the MPPT algorithm is to dynamically adjust the working state of the photovoltaic array so as to always track and output the maximum power point. This real-time optimization process enables the photovoltaic array to remain in the best working state under different environmental conditions, such as when the light intensity and temperature change. Therefore, the photovoltaic array can more effectively convert solar energy into electrical energy, improving the efficiency of energy capture and conversion. This efficiency improvement directly leads to an increase in the overall output electrical signal of the system, thereby providing more clean energy for the power grid. The present application can optimize the performance of the photovoltaic array and improve the efficiency and reliability of solar power generation through precise energy management.

[0095] S04: Controlling the DC-DC converter according to the reactive power, the rotor current state signal and the electrical signal, so that the DC-DC converter adjusts the output of the photovoltaic array and the double-fed wind turbine.

[0096] More specifically, the present application can eliminate the need for dedicated inverters for photovoltaic units by connecting the photovoltaic system to the DC link of the DFIG through a DC-DC converter. The system can meet the requirements of new grid regulations and achieve fault ride-through without adding additional costs. In the event of a grid fault, the DC link voltage of the DFIG can be effectively controlled through the control strategy to reduce the risk of rotor overcurrent; the response speed and stability of the system are improved by automatically adjusting the controller gain. The entire fault voltage control process of the present application is as follows Figure 3 As shown. The cost is reduced by connecting the PV system to the DC link of the Doubly fed Induction Generator (DFIG) through a DC-DC converter. Under normal operating conditions, the DC-DC converter controls the active power of the hybrid wind / PV system. When a grid fault occurs, the grid-side converter (GSC) operates as a static reactive power compensator (STATCOM) to inject reactive power into the grid, while the DC-DC converter controls the DC link voltage of the DFIG.

[0097] The present application realizes rapid response and effective management of power grid faults by integrating the coordinated work of current limiting devices, grid-side converters, rotor-side converters, DC-DC converters and photovoltaic arrays. First, as a monitoring point of the power grid status, the current limiting device can capture the fault signals of the power grid in time and quickly transmit these signals to the grid-side converter and the rotor-side converter, ensuring that the system is instantly aware of the abnormality of the power grid. The grid-side converter generates reactive power according to the fault signal to support the stability of the power grid, and sends a reactive power generation signal to the DC-DC converter, which helps the system adjust the energy output at the overall level. The rotor-side converter controls the rotor current of the doubly fed wind turbine according to the fault signal, and sends a rotor current state signal to the DC-DC converter to ensure the stable operation of the wind power generation part. The photovoltaic array sends an electrical signal to the DC-DC converter, so that the system can adjust the energy flow according to the real-time output of photovoltaic power generation. The DC-DC converter integrates the reactive power generation signal, the rotor current state signal and the electrical signal of the photovoltaic array, dynamically adjusts the energy flow between the photovoltaic array and the DC link of the doubly fed wind turbine, and maintains the energy balance of the system. Combining these measures, the present application not only improves the adaptability and stability of the power generation system to grid faults, but also optimizes energy management, reduces the impact on the grid, and improves the reliability and stability of the entire power system, thereby solving the problem that the existing technology cannot efficiently control the fault voltage of the wind photovoltaic system.

[0098] Embodiment 2

[0099] Please refer to Figure 4 , which is a fault voltage control device for a power generation system provided in an embodiment of the present application.

[0100] In this embodiment, the fault voltage control device of the power generation system includes a receiving module 10 , a control module 20 , an acquisition module 30 and an adjustment module 40 .

[0101] The fault voltage control method of the power generation system of the present application is applicable to the power generation system, which includes: a photovoltaic array, a double-fed wind turbine, a DC-DC converter, a grid-side converter, a rotor-side converter and a current limiting device, such as Figure 2 As shown, specifically:

[0102] The current limiting device is connected to the power grid, and is connected to the grid-side converter and the double-fed wind turbine;

[0103] The grid-side converter is connected to the DC-DC converter;

[0104] The rotor-side converter is connected to the doubly-fed wind turbine and to the DC-DC converter;

[0105] The DC-DC converter is connected to the photovoltaic array.

[0106] The receiving module 10 is used to receive a fault signal of the power grid system.

[0107] More specifically, the fault signal is obtained by controlling a current limiting device so that the current limiting device detects an abnormal signal in the power grid system.

[0108] The control module 20 is used to control the grid-side converter to generate reactive power and control the rotor-side converter to generate a rotor current signal according to the fault signal.

[0109] As a preferred embodiment of the second embodiment, controlling the grid-side converter to generate reactive power according to the fault signal is specifically:

[0110] Controlling the grid-side converter to generate reactive power according to the fault signal, the PI controller and the first preset power value;

[0111] More specifically, the PI controller is:

[0112] Fuzzy PI control is an advanced control strategy that combines traditional proportional integral (PI) control with fuzzy logic to deal with uncertainty and nonlinearity. Fuzzy PI control dynamically adjusts two key parameters of the PI controller by introducing fuzzy logic: proportional gain (Kp) and integral gain (Ki). This method is particularly suitable for systems where it is difficult to establish an accurate mathematical model, or when system parameters and environmental conditions change over time. The fuzzy logic controller is the core of fuzzy PI control, which uses fuzzy set theory to deal with input uncertainty and ambiguity. FLC usually includes the following four main parts:

[0113] (1) Fuzzification: Converting precise input data into fuzzy values. This usually involves defining a fuzzy set and the corresponding membership function.

[0114] (2) Rule Evaluation: Process the fuzzified input according to the defined fuzzy rules. These rules are usually if-then statements based on expert knowledge or experience.

[0115] (3) Decision Making: Evaluate the results of fuzzy rules by applying certain logical operations (such as maximum-minimum synthesis) and generate output fuzzy sets.

[0116] (4) Defuzzification: Convert fuzzy output into precise control value.

[0117] In a fuzzy PI control system, the Kp and Ki parameters of the PI controller are dynamically adjusted based on the real-time performance of the system. The adjustment process usually follows these steps:

[0118] (1) Error and change in error are used as inputs to the FLC. These inputs reflect the current state and trend of the system.

[0119] (2) The FLC processes these inputs according to preset rules to determine the adjustment values ​​for Kp and Ki. For example, if the error is large and the error changes quickly, the FLC may decide to increase Kp to respond quickly.

[0120] (3) The adjusted Kp and Ki are used to update the PI controller, thereby optimizing the control effect in real time.

[0121] When implementing fuzzy PI control, the following steps are required:

[0122] (1) System modeling and analysis: Determine the dynamic characteristics and control requirements of the system.

[0123] (2) Design FLC: define input and output variables, membership functions, fuzzy rules and defuzzification methods.

[0124] (3) Integrated PI controller: Integrate the FLC with the PI controller to ensure dynamic adjustment of Kp and Ki.

[0125] (4) Simulation and testing: Test the control system under different conditions to verify its performance and stability.

[0126] (5) Adjustment and optimization: Adjust the fuzzy rules and controller parameters according to the test results to optimize the system performance.

[0127] In this preferred embodiment, the present application controls the grid-side converter to generate reactive power by combining a fault signal, a PI controller and a first preset power value, which can effectively improve the responsiveness and stability of the power generation system in the face of a grid fault. First, the real-time monitoring of the fault signal enables the system to quickly identify the abnormal state of the grid, providing the necessary premise for subsequent control actions. Then, the PI controller dynamically adjusts its output according to this signal and the preset reactive power value to accurately control the behavior of the grid-side converter. The proportional part of the PI controller can quickly respond to immediate changes in the state of the grid, while the integral part can eliminate long-term errors and ensure the stable output of reactive power. This control strategy can not only respond quickly to grid faults, but also maintain the stability of the grid voltage and frequency during faults, reducing the impact on the grid.

[0128] As a preferred embodiment of the second embodiment, the step of controlling the rotor-side converter to generate a rotor current signal according to the fault signal is specifically as follows:

[0129] Obtaining a three-phase voltage signal according to the fault signal, the second preset power value and the PI controller;

[0130] According to the three-phase voltage signal, the rotor-side converter is controlled to generate a rotor current signal.

[0131] In this preferred embodiment, the present application controls the rotor-side converter to generate a rotor current signal by combining a fault signal, a second preset power value and a PI controller, which can effectively improve the performance and stability of the wind photovoltaic power generation system in the event of a power grid failure. First, real-time monitoring of the fault signal enables the system to quickly identify abnormal conditions of the power grid, which is the key first step to ensure timely response of the system. Next, the PI controller dynamically adjusts its output according to the fault signal and the second preset power value, wherein the proportional part can quickly respond to immediate changes in the power grid state, while the integral part can eliminate long-term errors and ensure stable output of the rotor current. This control strategy can not only respond quickly to power grid failures, but also maintain the stability of the power grid voltage and frequency during the fault, reducing the impact on the power grid.

[0132] As a preferred embodiment of the second embodiment, after controlling the rotor-side converter to generate a rotor current signal according to the fault signal, the method further includes:

[0133] When the rotor current exceeds a preset threshold, the double-fed wind turbine is controlled to be disconnected from the power grid system.

[0134] In this preferred embodiment, when the rotor current exceeds the preset threshold, the system will control the double-fed wind turbine to disconnect from the grid, avoiding equipment damage and further grid instability caused by overcurrent. This design not only protects the power generation equipment from damage, but also reduces the impact of grid failure on the entire power system, improving the reliability and safety of the system.

[0135] The acquisition module 30 is used to acquire the electrical signal output by the photovoltaic array.

[0136] As a preferred embodiment of the second embodiment, the step of obtaining the electrical signal output by the photovoltaic array is specifically:

[0137] According to the maximum power point tracking algorithm, the maximum power of the photovoltaic array is controlled to be extracted, so that the photovoltaic array outputs an electrical signal according to the maximum power.

[0138] The maximum power point tracking algorithm is specifically:

[0139] By adjusting the array terminal voltage reference from V1 to V2, the output power increment dP=P2-P1 is positive, so the algorithm should continue to increase the terminal voltage to V3. When the voltage increases from V2 to V3, the output power increment dP=P3-P2 is positive, so the algorithm increases the terminal voltage from V3 to V4. At this time, the output power difference (dP=P4-P3) is negative, and the terminal reference voltage moves in the opposite direction. The terminal voltage should return from V4 to V3. This means that the power of the PV will continue to fluctuate before approaching the maximum power point (MPP). The goal of the MPPT algorithm is to find the point where the dP / dV value becomes zero. When dP / dV is positive, the terminal voltage of the PV array should be increased; conversely, if dP / dV is negative, the terminal voltage should be reduced. Therefore, dP / dV can be derived from voltage and current:

[0140]

[0141] Let dP / dV=0.0, we can get the following formula:

[0142]

[0143] But the above method fails when the sampled voltage does not vary from one sample to another, the above equation results in division by zero, so multiplying both sides of the equation by dV gives the following formula:

[0144] dP=V·dI+I·dV;

[0145] dP=V·dI;

[0146] Regardless of whether V is a positive number or a constant, an increase in output power P is accompanied by an increase in output current. Similarly, a decrease in output power P is accompanied by a decrease in output current. This implementation makes it possible to track the maximum power point even when the sampling terminal voltage is constant.

[0147] In this preferred embodiment, the present application can significantly improve the efficiency and energy output of the photovoltaic power generation system by using the maximum power point tracking (MPPT) algorithm to control the method of outputting electrical signals from the photovoltaic array. The core of the MPPT algorithm is to dynamically adjust the working state of the photovoltaic array so as to always track and output the maximum power point. This real-time optimization process enables the photovoltaic array to remain in the best working state under different environmental conditions, such as when the light intensity and temperature change. Therefore, the photovoltaic array can more effectively convert solar energy into electrical energy, improving the efficiency of energy capture and conversion. This efficiency improvement directly leads to an increase in the overall output electrical signal of the system, thereby providing more clean energy for the power grid. The present application can optimize the performance of the photovoltaic array and improve the efficiency and reliability of solar power generation through precise energy management.

[0148] The adjustment module 40 is used to control the DC-DC converter according to the reactive power, the rotor current state signal and the electrical signal, so that the DC-DC converter adjusts the output of the photovoltaic array and the double-fed wind turbine.

[0149] More specifically, the present application can eliminate the need for dedicated inverters for photovoltaic units by connecting the photovoltaic system to the DC link of the DFIG through a DC-DC converter. The system can meet the requirements of new grid regulations and achieve fault ride-through without adding additional costs. In the event of a grid fault, the DC link voltage of the DFIG can be effectively controlled through the control strategy to reduce the risk of rotor overcurrent; the response speed and stability of the system are improved by automatically adjusting the controller gain. The entire fault voltage control process of the present application is as follows Figure 3 As shown. The cost is reduced by connecting the PV system to the DC link of the Doubly fed Induction Generator (DFIG) through a DC-DC converter. Under normal operating conditions, the DC-DC converter controls the active power of the hybrid wind / PV system. When a grid fault occurs, the grid-side converter (GSC) operates as a static reactive power compensator (STATCOM) to inject reactive power into the grid, while the DC-DC converter controls the DC link voltage of the DFIG.

[0150] This device uses four modules to divide the work and coordinate work to better control the fault voltage. This application realizes rapid response and effective management of power grid faults by integrating the current limiting device, grid-side converter, rotor-side converter, DC-DC converter and photovoltaic array. First, as a monitoring point of the power grid status, the current limiting device can capture the fault signal of the power grid in time and quickly transmit these signals to the grid-side converter and the rotor-side converter, ensuring the system's instant perception of power grid abnormalities. The grid-side converter generates reactive power according to the fault signal to support the stability of the power grid, and sends a reactive power generation signal to the DC-DC converter, which helps the system adjust the energy output at the overall level. The rotor-side converter controls the rotor current of the doubly fed wind turbine according to the fault signal, and sends a rotor current state signal to the DC-DC converter to ensure the stable operation of the wind power generation part. The photovoltaic array sends an electrical signal to the DC-DC converter, so that the system can adjust the energy flow according to the real-time output of photovoltaic power generation. The DC-DC converter integrates the reactive power generation signal, the rotor current state signal and the electrical signal of the photovoltaic array, dynamically adjusts the energy flow between the photovoltaic array and the DC link of the doubly fed wind turbine, and maintains the energy balance of the system. Combining these measures, this application not only improves the adaptability and stability of the power generation system to grid failures, but also optimizes energy management, reduces the impact on the grid, and improves the reliability and stability of the entire power system. This solves the problem that the existing technology cannot efficiently control the fault voltage of the wind photovoltaic system.

[0151] Embodiment three:

[0152] An embodiment of the present application provides a computer-readable storage medium, wherein the computer-readable storage medium includes a stored computer program, wherein when the computer program is executed, the device where the computer-readable storage medium is located is controlled to execute the method for controlling a fault voltage of a power generation system;

[0153] Wherein, the fault voltage control method of a power generation system, if implemented in the form of a software functional unit and used as an independent product, can be stored in a computer-readable storage medium. Based on such an understanding, the present invention implements all or part of the processes in the above-mentioned embodiment method, and can also be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium, and the computer program can implement the steps of the above-mentioned various method embodiments when executed by a processor. Wherein, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form, etc. The computer-readable medium can include: any entity or device capable of carrying the computer program code, recording medium, U disk, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), electric carrier signal, telecommunication signal and software distribution medium, etc.

[0154] Embodiment 4

[0155] The present application provides a terminal device, including a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, and when the processor executes the computer program, it implements any one of the fault voltage control methods for a power generation system as described in Example 1.

[0156] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. It is particularly pointed out that for those skilled in the art, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the scope of protection of the present invention.

Claims

1. A fault voltage control method for a power generation system, characterized in that: include: Receiving fault signals from the power grid system; According to the fault signal, controlling the grid-side converter to generate reactive power, and controlling the rotor-side converter to generate a rotor current signal; Acquiring an electrical signal output by a photovoltaic array; The DC-DC converter is controlled according to the reactive power, the rotor current state signal and the electrical signal, so that the DC-DC converter adjusts the output of the photovoltaic array and the double-fed wind turbine.

2. The fault voltage control method of the power generation system according to claim 1, characterized in that: Applicable to a power generation system, the power generation system comprising: a photovoltaic array, a double-fed wind turbine, a DC-DC converter, a grid-side converter, a rotor-side converter and a current limiting device, specifically: The current limiting device is connected to the power grid, and is connected to the grid-side converter and the double-fed wind turbine; The grid-side converter is connected to the DC-DC converter; The rotor-side converter is connected to the doubly-fed wind turbine and to the DC-DC converter; The DC-DC converter is connected to the photovoltaic array.

3. The fault voltage control method of the power generation system according to claim 1, characterized in that: According to the fault signal, controlling the grid-side converter to generate reactive power is specifically: According to the fault signal, the PI controller and the first preset power value, the grid-side converter is controlled to generate reactive power.

4. The fault voltage control method of the power generation system according to claim 1, characterized in that: The controlling the rotor-side converter to generate a rotor current signal according to the fault signal is specifically as follows: Obtaining a three-phase voltage signal according to the fault signal, the second preset power value and the PI controller; According to the three-phase voltage signal, the rotor-side converter is controlled to generate a rotor current signal.

5. The fault voltage control method of the power generation system according to claim 1, characterized in that: After the method controls the rotor-side converter to generate a rotor current signal according to the fault signal, the method further includes: When the rotor current exceeds a preset threshold, the double-fed wind turbine is controlled to be disconnected from the power grid system.

6. The fault voltage control method of a power generation system according to claim 1, characterized in that: The step of obtaining the electrical signal output by the photovoltaic array is specifically as follows: According to the maximum power point tracking algorithm, the maximum power of the photovoltaic array is controlled to be extracted, so that the photovoltaic array outputs an electrical signal according to the maximum power.

7. The fault voltage control method of a power generation system according to claim 1, characterized in that: The receiving of the fault signal of the power grid system is specifically: The current limiting device is controlled to detect a fault signal of the power grid system to obtain a fault signal.

8. A fault voltage control device for a power generation system, characterized in that: It includes a receiving module, a control module, an acquisition module and an adjustment module; The receiving module is used to receive the fault signal of the power grid system; The control module is used to control the grid-side converter to generate reactive power and control the rotor-side converter to generate a rotor current signal according to the fault signal; The acquisition module is used to acquire the electrical signal output by the photovoltaic array; The adjustment module is used to control the DC-DC converter according to the reactive power, the rotor current state signal and the electrical signal, so that the DC-DC converter adjusts the output of the photovoltaic array and the double-fed wind turbine.

9. A computer-readable storage medium, characterized in that: The computer-readable storage medium includes a stored computer program, wherein when the computer program is executed, the device where the computer-readable storage medium is located is controlled to execute the fault voltage control method for the power generation system according to any one of claims 1 to 7.

10. A terminal device, characterized in that: The method comprises a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, wherein when the processor executes the computer program, the fault voltage control method of the power generation system according to any one of claims 1 to 7 is implemented.

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