A frequency modulation control method for grid-connected energy storage of a wind storage system

Abstract

The application discloses a VSG frequency modulation control method for network-constructing type energy storage in a wind storage system, and belongs to the field of power grid regulation. The method comprises the following steps: acquiring the topological structure of the wind storage system; acquiring the control structure of a network-constructing subsystem based on the topological structure of the wind storage system; acquiring the mathematical model of each network-constructing subsystem based on the network-constructing subsystem; acquiring the key parameters of network-constructing frequency modulation based on the mathematical model of the network-constructing subsystem; and performing VSG frequency modulation control on the network-constructing based on the key parameters of network-constructing frequency modulation. The method solves the problem that, in the current network-constructing adjustment, the VSG frequency modulation control method is only based on the virtual synchronous machine transfer function itself, lacks analysis of the influence of thermal power generating units and wind power generating systems on primary frequency modulation, and makes it difficult to restore the frequency to the rated value in the primary frequency modulation process of the wind storage system. Through analysis of the overall mechanism of network construction, the frequency can be restored to the rated value, and the control precision is improved.

Description

Technical Field

[0001] The present application belongs to the field of power grid regulation, and specifically, to a VSG frequency regulation control method for grid-type energy storage in a wind-storage system. Background Art

[0002] Globally, the energy mix is ​​evolving towards a low-carbon, clean, and sustainable approach. The increasing proportion of renewable energy sources is leading to a decrease in grid inertia and worsening grid stability. VSG technology offers the advantage of inertia in renewable energy converters, improving grid stability. VSG technology features flexible damping coefficients and moment of inertia. Adaptively changing the moment of inertia and damping coefficient during primary frequency regulation in wind-storage systems can help quickly recover system frequency after disturbances, improving system stability. Current analysis of VSG control technology relies solely on the virtual synchronous generator transfer function itself, lacking an analysis of the impact of traditional thermal and wind power generation systems on primary frequency regulation. Furthermore, conventional VSG adaptive control typically links the moment of inertia and damping coefficient to the frequency change rate and the grid frequency itself to adaptively adjust the damping coefficient and moment of inertia. However, during primary frequency regulation in wind-storage systems, the frequency cannot be restored to its rated value of 50 Hz, resulting in frequency drift. Furthermore, the moment of inertia and damping coefficient cannot be restored to their initial values ​​after adaptive adjustments, causing system instability and exacerbating grid deterioration.

[0003] Therefore, how to establish a set of methods that fully considers the entire network structure, accurately analyzes the impact of moment of inertia and damping coefficient on frequency modulation performance, and establishes a reasonable VSG frequency modulation control method is a technical problem that technical personnel in this field urgently need to solve. Summary of the Invention

[0004] In order to solve the problems in the current VSG frequency regulation control method that the primary frequency regulation process of the wind-storage system cannot be restored to the rated value, and that other power generation systems in the grid are not fully considered, this application discloses a VSG frequency regulation control method for grid-type energy storage in a wind-storage system, specifically:

[0005] A VSG frequency modulation control method for grid-type energy storage in a wind-storage system, the method comprising:

[0006] Obtain the topology of the wind-storage system;

[0007] Based on the topological structure of the wind-storage system, a control structure of the network subsystem is obtained;

[0008] Based on the networking subsystems, obtaining a mathematical model of each of the networking subsystems;

[0009] Based on the mathematical model of the networking subsystem, key parameters of the networking frequency modulation are obtained;

[0010] Based on the key parameters of the network frequency modulation, VSG frequency modulation control is performed on the network.

[0011] Optionally, obtaining the topology of the wind-storage system includes:

[0012] Obtain the composition of the wind-storage system and the connection relationship between subsystems within the network;

[0013] Based on the connection relationship between the subsystems in the network, the topological structure of the wind-storage system is obtained.

[0014] Optionally, obtaining a control structure of a network subsystem based on the topological structure of the wind-storage system includes:

[0015] Based on the topological structure of the wind-storage system, all network subsystems are obtained;

[0016] Based on the role of the grid-forming subsystem in the wind-storage system, obtaining the type of the grid-forming subsystem;

[0017] Based on the type and composition of the networking subsystem, obtaining a control structure of the networking subsystem;

[0018] The grid-building subsystem includes an energy storage system, a thermal power system, and a wind power system.

[0019] Optionally, obtaining a mathematical model of each of the networking subsystems based on the control structure of the networking subsystem includes:

[0020] Based on the control structure of the networking subsystem, obtaining a control block diagram of the networking subsystem;

[0021] Based on the control block diagram of the networking subsystem, a mathematical model of each networking subsystem is obtained.

[0022] Optionally, obtaining a mathematical model of each networking subsystem based on the control block diagram of the networking subsystem includes:

[0023] Based on the control block diagram of the grid-forming subsystem, obtaining control block diagrams of the energy storage system, the thermal power system, and the wind power system;

[0024] Based on the control block diagram of the grid-forming subsystem, among the mathematical models of the various grid-forming subsystems obtained, the mathematical model of the energy storage system is:

[0025] ;

[0026] in, is the VSG frequency modulation coefficient; , is the grid connection point voltage, G 1Indicates the frequency modulation coefficient gain; is the inverter output electromotive force, is the VSG output line impedance; s is a variable in the complex frequency domain; D represents the damping coefficient; J is the moment of inertia; ω 0 represents the cutoff frequency; P b Represents the output of the energy storage system;

[0027] Δf Indicates the network frequency modulation frequency; G b ( s ) represents the energy storage equivalent transfer function;

[0028] The mathematical model of the thermal power system is:

[0029] ;

[0030] in, is the speed regulator action time constant; is the reheater time constant; is the time constant of the main steam inlet chamber; is the high-pressure turbine mechanical torque; F RH represents the high-pressure turbine reheat mechanical torque; K g Expressed as the frequency regulation coefficient of thermal power units; P g Indicates the inertia response output power of the thermal power unit; Represents the equivalent transfer function of the thermal power unit.

[0031] Optionally, also include:

[0032] Based on the energy storage system and the wind power system, a mathematical model of the wind-storage system is obtained. The mathematical model of the wind-storage system is:

[0033] ;

[0034] in, H sys represents the inertia of the wind-storage system; D sys represents the damping coefficient of the wind storage system; ΔP L ( s ) represents the load disturbance, Δf ( s ) represents the frequency of the networking system.

[0035] Optionally, obtaining key parameters of network frequency modulation based on the mathematical model of the network subsystem includes:

[0036] Based on the mathematical model of the grid subsystem, a mathematical model of the wind energy storage system is obtained;

[0037] Based on the mathematical model of the wind-storage system, obtaining simulation results;

[0038] Based on the simulation results, key parameters of network frequency modulation are obtained;

[0039] The key parameters include moment of inertia and damping coefficient.

[0040] Optionally, the performing VSG frequency modulation control on the network based on the key parameters of the network frequency modulation includes:

[0041] Establish a network frequency modulation frequency and a key parameter equation group of the network frequency modulation, the equation group is:

[0042] when hour ;

[0043] when hour ; ;

[0044] described Δf Indicates the network frequency modulation frequency, 、 for J and D The initial value of is the derivative of the system frequency, 、 They are J and D The threshold of change, that is, when When it is less than the threshold, the system frequency can be considered to have reached a steady state. 、 They are J and D The coefficient of change determines J and D the speed of change;

[0045] Based on the equation group, the key coefficients of the network are adjusted to perform VSG frequency modulation control.

[0046] The beneficial effects of this application include:

[0047] 1. The adaptive adjustment of VSG is realized. In the technical solution of the application, the influence of thermal power generating units in the power system on the frequency modulation performance is considered, the relationship among the moment of inertia, the damping coefficient and the frequency change rate is analyzed by analyzing the frequency change trend, a corresponding mathematical model is established, and then the control of the entire network operation parameters is performed based on the obtained mathematical model, so as to ensure the adaptive adjustment of VSG.

[0048] 2. The system frequency response speed is improved. In the technical solution of the application, in the specific network adjustment in the VSG frequency modulation control, the damping coefficient and the moment of inertia can be adaptively adjusted based on the established network mathematical model, so that the output frequency of the network can be the same as the rated frequency during the adjustment process, and the frequency response speed of the control process can also be improved during the specific adjustment process.

[0049] 3. The adjustment of the output frequency is realized. In the technical solution of the application, based on the adjustment of the moment of inertia and the damping coefficient, the final output frequency of the network can be the same as the rated frequency, so that the accurate adjustment and control of the output frequency are realized. BRIEF DESCRIPTION OF DRAWINGS

[0050] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the drawings used in the embodiments of the application or the prior art will be briefly introduced as follows. Obviously, the following description is only some embodiments of the application, and other drawings can also be obtained by those skilled in the art without creative labor. The drawings are used to provide further understanding of the disclosure and constitute a part of the specification, and are used to explain the disclosure together with the following specific embodiments, but do not constitute a limitation on the disclosure. In the drawings:

[0051] Figure 1 A flow chart of a VSG frequency modulation control method of network type energy storage in a wind storage system is provided for the embodiments of the application.

[0052] Figure 2 A network topology structure diagram of a VSG frequency modulation control method of network type energy storage in a wind storage system is provided for the embodiments of the application.

[0053] Figure 3 A storage VSG control model diagram of a VSG frequency modulation control method of network type energy storage in a wind storage system is provided for the embodiments of the application.

[0054] Figure 4 A diagram of the influence of the damping coefficient on the system frequency of a VSG frequency modulation control method of network type energy storage in a wind storage system is provided for the embodiments of the application.

[0055] Figure 5 A rotational inertia of a VSG frequency control method of network-constructed energy storage in a wind storage system provided in an embodiment of the present application has an influence on a system frequency graph;

[0056] Figure 6 A frequency change and a rotational inertia and damping coefficient change comparison graph when a system load suddenly increases in a VSG frequency control method of network-constructed energy storage in a wind storage system provided in an embodiment of the present application;

[0057] Figure 7 A frequency change and a rotational inertia and damping coefficient change comparison graph when a system load suddenly decreases in a VSG frequency control method of network-constructed energy storage in a wind storage system provided in an embodiment of the present application;

[0058] Figure 8 A frequency change and a rotational inertia and damping coefficient change comparison graph when a system wind speed suddenly increases in a VSG frequency control method of network-constructed energy storage in a wind storage system provided in an embodiment of the present application;

[0059] Figure 9 A frequency change and a rotational inertia and damping coefficient change comparison graph when a system wind speed suddenly decreases in a VSG frequency control method of network-constructed energy storage in a wind storage system provided in an embodiment of the present application. DETAILED DESCRIPTION

[0060] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application. In addition, in the embodiments of the present application, “first”, “second”, etc. are used to distinguish similar objects, and do not necessarily describe a specific order or sequence.

[0061] In the operation of network construction, the VSG frequency control method can improve the operation stability of the entire network construction system, and has been applied in a large number of network construction systems at present. However, from the effect, for the primary frequency modulation process in the wind storage system, the final output frequency cannot be restored to the rated value 50 Hz, which reduces the power supply performance. In addition, the currently used VSG frequency control method is based on the virtual synchronous machine transfer function itself in real time, which lacks analysis of the influence of primary frequency modulation on the actual existing system in network construction, including thermal power generating units, wind power generation systems, etc., resulting in a large actual error and also reducing the power supply performance. In the technical solutions of the present application, the existing problems are solved.

[0062] The present application discloses a VSG frequency control method of network-constructed energy storage in a wind storage system, as shown in Figure 1 As shown, the embodiment of the present application provides a flow chart of a VSG frequency modulation control method for grid-type energy storage in a wind-storage system, including:

[0063] S110: Obtain the topological structure of the wind energy storage system.

[0064] S120: Based on the topological structure of the wind-storage system, obtain a control structure of a network subsystem.

[0065] S130: Based on the networking subsystems, obtain a mathematical model of each of the networking subsystems.

[0066] S140: Based on the mathematical model of the networking subsystem, key parameters of the networking frequency modulation are obtained.

[0067] S150: Based on the key parameters of the network frequency modulation, perform VSG frequency modulation control on the network.

[0068] The purpose of all the above steps is to determine the subsystems in the current network based on the entire distribution network system, and then perform VSG frequency control based on the obtained mathematical model.

[0069] Below, all the above steps will be explained in detail, specifically:

[0070] The obtaining of the topological structure of the wind energy storage system includes:

[0071] Obtain the composition of the wind-storage system and the connection relationship between subsystems within the network;

[0072] Based on the connection relationship between the subsystems in the network, the topological structure of the wind-storage system is obtained.

[0073] The wind-storage system topology diagram shows the entire system consisting of a wind turbine, an energy storage system, and loads. The wind turbine continuously inputs a rated power of 100 MW into the grid, and the wind turbines utilize maximum power tracking (MPPT) control. The energy storage system utilizes grid-connected VSG control with a maximum output power of 20 MW. When system power is disturbed, the energy storage rapidly absorbs excess energy on the bus or supplements the power shortfall, regulating the system frequency. The load is connected to the 220 kV grid, with a maximum disturbance of ±20 MW. To simulate the primary frequency regulation characteristics of the grid, synchronous generators with a rated capacity of 300 MW were used in place of traditional thermal power units.

[0074] The parameters of each subsystem in the wind-storage system are shown in the following table:

[0075] ;

[0076] The obtaining of the control structure of the network subsystem based on the topological structure of the wind-storage system includes:

[0077] Based on the topological structure of the wind-storage system, all network subsystems are obtained;

[0078] Based on the role of the grid-forming subsystem in the wind-storage system, obtaining the type of the grid-forming subsystem;

[0079] Based on the type and composition of the networking subsystem, obtaining a control structure of the networking subsystem;

[0080] The grid-building subsystem includes an energy storage system, a thermal power system, and a wind power system.

[0081] Among them, after determining the subsystem, it is necessary to determine the topology of the wind storage system based on the connection relationship between the subsystems of the network, such as Figure 2 As shown, it is a network topology diagram of a VSG frequency modulation control method for grid-type energy storage in a wind-storage system provided by an embodiment of the present application.

[0082] The external control loop utilizes active-frequency and reactive-voltage droop control to generate voltage phase and amplitude signals, allowing for adaptive changes in the moment of inertia J and damping coefficient D. Internally, dual closed-loop voltage-current decoupling control is employed, ultimately sending control signals to the energy storage converter via an SVPWM signal generator.

[0083] The acquiring of the mathematical model of each of the networking subsystems based on the control structure of the networking subsystems includes:

[0084] Based on the control structure of the networking subsystem, obtaining a control block diagram of the networking subsystem;

[0085] Based on the control block diagram of the networking subsystem, a mathematical model of each networking subsystem is obtained.

[0086] After obtaining the VSG control block diagram and determining the entire network topology, the impact of the load on the network can be determined, and the mathematical model of the entire network system can be determined.

[0087] When the system load is disturbed, the wind-storage system needs to maintain power balance. The wind power generation system, energy storage system, and thermal power units simultaneously output or absorb power to maintain node power balance. The following expression is satisfied:

[0088] ;

[0089] Where, is the load disturbance, To power the fan, Contribute to the power grid, The wind-storage system is simplified into a mathematical model to study the impact of load disturbance on system output and system frequency.

[0090] Among them, the frequency regulation control model of the wind-storage system is as follows: Figure 3 As shown, it is a VSG control model diagram of a VSG frequency modulation control method for grid-type energy storage in a wind-storage system provided by an embodiment of the present application, wherein: is the equivalent transfer function of the fan, is the equivalent transfer function of the thermal power unit, is the energy storage equivalent transfer function. is the load disturbance, is the wind turbine inertia response output power, is the inertial response output power of the thermal power unit, is the inertial response output power of the energy storage VSG, is the frequency modulation coefficient of the fan, is the frequency regulation coefficient of the thermal power unit, is the frequency modulation coefficient of energy storage. 、 are the system inertia and the system damping coefficient respectively.

[0091] Due to the wind storage system of the present invention, the wind turbine does not participate in the primary frequency regulation, so the wind turbine output .

[0092] The obtaining of mathematical models of the respective networking subsystems based on the control block diagram of the networking subsystems includes:

[0093] Based on the control block diagram of the grid-forming subsystem, obtaining control block diagrams of the energy storage system, the thermal power system, and the wind power system;

[0094] Based on the control block diagram of the grid-forming subsystem, among the mathematical models of the various grid-forming subsystems obtained, the mathematical model of the energy storage system is:

[0095] ;

[0096] in, is the VSG frequency modulation coefficient; , is the grid connection point voltage, G 1 Indicates the frequency modulation coefficient gain; is the inverter output electromotive force, is the VSG output line impedance; s is a variable in the complex frequency domain; D represents the damping coefficient; J is the moment of inertia; ω 0 represents the cutoff frequency; Pb Represents the output of the energy storage system;

[0097] Δf Indicates the network frequency modulation frequency; G b ( s ) represents the energy storage equivalent transfer function;

[0098] Among them, the energy storage system adopts VSG control, and the overall transfer function is obtained, which is the mathematical model.

[0099] The mathematical model of the thermal power system is:

[0100] ;

[0101] in, is the speed regulator action time constant; is the reheater time constant; is the time constant of the main steam inlet chamber; is the high-pressure turbine mechanical torque; F RH represents the high-pressure turbine reheat mechanical torque; K g Expressed as the frequency regulation coefficient of thermal power units; P g Indicates the inertia response output power of the thermal power unit; Represents the equivalent transfer function of the thermal power unit.

[0102] Among them, the thermal power unit speed governor and the thermal power unit turbine are important factors affecting the response speed of the thermal power unit speed governor. Therefore, considering the thermal power unit turbine and the thermal power unit speed governor, a proportional control scheme is adopted.

[0103] in, The speed regulator action time constant is generally set to 0.2s; is the reheater time constant, which is generally 7.0s; The time constant of the main steam inlet chamber is generally 0.3s; It is the mechanical torque of the high-pressure turbine, and is generally taken as 0.3.

[0104] Also includes:

[0105] Based on the energy storage system and the wind power system, a mathematical model of the wind-storage system is obtained. The mathematical model of the wind-storage system is:

[0106] ;

[0107] in, H sys represents the inertia of the wind-storage system; Dsys represents the damping coefficient of the wind storage system; ΔP L ( s ) represents the load disturbance, Δf ( s ) represents the frequency of the networking system.

[0108] After the mathematical model is obtained, a characteristic equation is obtained based on the mathematical model. The characteristic equation is expressed as:

[0109] The obtaining of key parameters of network frequency modulation based on the mathematical model of the network subsystem includes:

[0110] Based on the mathematical model of the grid subsystem, a mathematical model of the wind energy storage system is obtained;

[0111] Based on the mathematical model of the wind-storage system, obtaining simulation results;

[0112] Based on the simulation results, key parameters of network frequency modulation are obtained;

[0113] The key parameters include moment of inertia and damping coefficient.

[0114] Among them, after obtaining the mathematical model of the entire subsystem, the above corresponding values ​​are substituted into MATLAB to draw the root loci corresponding to the change of the single variable J from 0.01 to 250 and the main root loci corresponding to the change of the single variable D from 0 to 4000.

[0115] Since the characteristic equation of the system is a sixth-order polynomial, according to the fundamental theorem of algebra, this sixth-order equation has six roots (poles), each of which forms a trajectory as J changes. Each root trajectory shows the movement path of the corresponding pole as J increases, reflecting the effect of parameter J on the system's dynamic performance. For some poles, the root trajectory moves from the left half plane to the right half plane as J increases, indicating that the system has changed from a stable state to an unstable state.

[0116] The root locus plot of the single variable D shows that within a certain range, as D increases, the system's characteristic roots shift from the right half plane to the left half plane in the complex frequency domain, and the system transitions from unstable to stable. As D continues to increase, the system's characteristic roots shift toward the real axis, and the system transitions from underdamped to overdamped, slowing the response and increasing the settling time. Therefore, the value of D should not be too small, as this will lead to system instability. It should also not be too large, as this will result in slower response and longer settling time. The appropriate value for D should be tailored to the actual situation.

[0117] Among them, for the obtained simulation results, simulation image results of the moment of inertia J and the damping system D can be determined.

[0118] Among them, such as Figure 4 As shown in the figure, it is an influence diagram of the damping coefficient of the VSG frequency modulation control method of the grid-type energy storage in the wind storage system provided by the embodiment of the present application on the system frequency. It is necessary to determine the influence of the damping coefficient D on the VSG frequency modulation control result. The frequency change curve obtained by setting J=1 and D to 300, 600, 900, 1500, 3000, and 4000 is as shown in the figure. Figure 8 As shown in the figure, when the moment of inertia is fixed and the damping coefficient increases, the system's frequency response speed slows down, resulting in a longer recovery time. Therefore, when the system frequency recovers, a smaller D value should be used to increase the system frequency response speed. However, the VSG's damping coefficient D cannot be too small, as this will cause the VSG power output to oscillate and lead to system instability.

[0119] Among them, such as Figure 5 As shown in the figure, the influence of the moment of inertia on the system frequency of the VSG frequency modulation control method of the grid-type energy storage in the wind storage system provided by the embodiment of the present application is shown in the figure. The system power response curve and system frequency response curve obtained by setting D=900 and J to 0.01, 10, 20, 30, and 40 are shown in the figure. Figure 9 As shown in the figure, when the damping coefficient is fixed and the moment of inertia increases, the system frequency overshoot increases, and the settling time increases. Therefore, it is desirable to keep J small during the system frequency deviation phase to minimize overshoot. During the recovery phase, J should be large to facilitate rapid recovery of the primary frequency modulation. However, J should not be set too high. Excessively large J values ​​can lead to intensified system oscillations, multiple oscillations during the frequency recovery phase, prolonged settling time, and slowed primary frequency modulation recovery.

[0120] The VSG frequency modulation control of the network based on the key parameters of the network frequency modulation includes:

[0121] Establish a network frequency modulation frequency and a key parameter equation group of the network frequency modulation, the equation group is:

[0122] when hour ;

[0123] when hour ; ;

[0124] described Δf Indicates the network frequency modulation frequency, 、 for J and D The initial value of is the derivative of the system frequency, 、 They areJ and D The threshold of change, that is, when When it is less than the threshold, the system frequency can be considered to have reached a steady state. 、 They are J and D The coefficient of change determines J and D the speed of change;

[0125] Based on the equations, the key coefficients of the network are adjusted, and the retrograde VSG frequency modulation control is performed.

[0126] Among them, according to the influence of J and D on the dynamic response of the system frequency, it is hoped that the VSG output power can meet the fast response and reduce the adjustment time. The frequency response is divided into two stages: frequency deviation and frequency recovery. When the frequency deviates, J is appropriately reduced to reduce , reduce the overshoot of the system frequency. When the frequency recovers, increase J appropriately, increase , speeding up the frequency recovery process. The smaller D, the faster the VSG output power response speed. However, if D is too small, it will cause system instability. Therefore, D should be set to a limit and reduced as much as possible when the system frequency deviates from the stable value so that power can be replenished as quickly as possible.

[0127] in, ,when When , it means that the system load increases and the system frequency decreases. )< It is considered that the system frequency deviates from the stable point, and J should be reduced to make the system frequency overshoot. )> It is believed that the system frequency tends to be stable, and J should be increased at this time to increase , so that the system tends to be stable faster. Similarly, when When , it means that the system load is reduced and the system frequency is increased. )> It is considered that the system frequency deviates from the stable point. At this time, J should be reduced to reduce the system frequency overshoot. )< It is believed that the system frequency tends to a stable point, at this time J should be increased to increase , so that the system can stabilize faster. When the system frequency is considered to be stable, J is the initial value. .

[0128] when When the system frequency is considered to be in a stable state, D is the initial value. When the system frequency When , it is considered that the system frequency is in an unstable state and the missing power needs to be quickly supplemented to make the system frequency stable again. At this time, D should be reduced to make the VSG output power quickly.

[0129] After determining the key parameter equations, this application simulated the results obtained. A wind-storage system simulation model was built in MATLAB / Simulink simulation software for simulation verification. Four operating conditions were set up for the experiment: a sudden load increase of 20MW, a sudden load decrease of 20MW, a sudden wind speed increase of 1m / s, and a sudden wind speed decrease of 1m / s. The system frequency response curves and the changes in J and D were observed for traditional VSG control and the improved adaptive VSG control to verify the correctness of the theory.

[0130] When the system load suddenly increases, Figure 6 As shown, a comparison diagram of the frequency change, moment of inertia, and damping coefficient changes when the system load suddenly increases in a VSG frequency modulation control method for grid-type energy storage in a wind-storage system provided in an embodiment of the present application. When the system load suddenly increases at 0.5s, the time to reach the lowest point using the fixed optimal J and D frequencies is 0.121s. After using the adaptive algorithm, the time is shortened to 0.104s, and the minimum frequency increases from 49.81Hz to 49.82Hz. It can be seen that the use of the improved adaptive algorithm can effectively reduce the overshoot of the system frequency drop when the load suddenly increases, thereby improving the response speed.

[0131] When the system load suddenly drops, Figure 7 As shown, a comparison diagram of the frequency change, moment of inertia, and damping coefficient change during a sudden drop in system load for a VSG frequency modulation control method for grid-type energy storage in a wind-storage system provided in an embodiment of the present application. When the system load suddenly drops at 0.5s, the time to reach the highest point using the fixed optimal J and D frequencies is 0.130s. After using the adaptive algorithm, the time is shortened to 0.112s, and the maximum frequency is reduced from 50.20Hz to 50.18Hz. It can be seen that the use of the improved adaptive algorithm can effectively reduce the overshoot of the system frequency rise during a sudden load drop and improve the response speed.

[0132] When the wind speed suddenly increases, Figure 8 As shown, a comparison diagram of the frequency change, moment of inertia, and damping coefficient change when the system wind speed suddenly increases in a VSG frequency modulation control method for grid-type energy storage in a wind-storage system provided in an embodiment of the present application. When the system wind speed suddenly increases from 12m / s to 13m / s at 0.5s, the time to reach the highest point using the fixed optimal J and D frequencies is 0.127s. After using the adaptive algorithm, the time is shortened to 0.116s, and the maximum frequency is reduced from 50.24Hz to 50.22Hz. It can be seen that the use of the improved adaptive algorithm can effectively reduce the overshoot of the system frequency increase when the wind speed suddenly increases, thereby improving the response speed.

[0133] When the wind speed drops suddenly, Figure 9 As shown, a comparison diagram of the frequency change, moment of inertia, and damping coefficient change when the system wind speed suddenly drops in a VSG frequency modulation control method for grid-type energy storage in a wind-storage system provided in an embodiment of the present application. When the system wind speed suddenly drops from 12m / s to 11m / s at 0.5s, the time to reach the lowest point using the fixed optimal J and D frequencies is 0.128s. After using the adaptive algorithm, the time is shortened to 0.122s, and the minimum frequency is increased from 49.79Hz to 49.80Hz. It can be seen that the use of the improved adaptive algorithm can effectively reduce the overshoot of the system frequency drop when the wind speed suddenly drops, thereby improving the response speed.

[0134] Through comparative analysis under four working conditions, it can be seen that the improved VSG adaptive control can effectively improve the dynamic performance of the primary frequency regulation of the wind-storage system, shorten the adjustment time, and improve the system stability.

[0135] The beneficial effects of this application include:

[0136] 1. Adaptive adjustment of the VSG is achieved. The technical solution of this application takes into account the impact of thermal power units in the power system on frequency regulation performance. By analyzing the frequency variation trend and the relationship between the moment of inertia, damping coefficient, and frequency change rate, a corresponding mathematical model is established. The resulting mathematical model is then used to control the entire network operating parameters, thereby ensuring adaptive adjustment of the VSG.

[0137] 2. Improved system frequency response speed. In the technical solution of this application, for VSG frequency modulation control, during specific network adjustment, the damping coefficient and moment of inertia can be adaptively adjusted based on the established network mathematical model, thereby ensuring that the output frequency of the network is the same as the rated frequency during the adjustment process. At the same time, the frequency response speed of the control process can be fully improved during the specific adjustment process.

[0138] 3. Output frequency adjustment is achieved. In the technical solution of this application, the obtained control method, based on the adjustment of the moment of inertia and the damping coefficient, can make the final output frequency of the network the same as the rated frequency, thus achieving accurate adjustment and control of the output frequency.

[0139] Those skilled in the art will understand that all or part of the steps of the above-mentioned method embodiments can be implemented by hardware related to computer program instructions, and the aforementioned computer program can be stored in a non-volatile storage medium. When the computer program is executed, it executes the steps of the above-mentioned method embodiments. Alternatively, if the above-mentioned integrated unit of the present invention is implemented in the form of a software functional module and sold or used as an independent product, it can also be stored in a non-volatile storage medium. Based on this understanding, the technical solution of the embodiment of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product. The computer software product is stored in a non-volatile storage medium and includes a number of instructions for enabling an electronic device (which can be a personal computer, server, network device, etc.) to execute all or part of the methods described in each embodiment of the present invention.

[0140] The above description is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with this technical field can easily think of changes or replacements within the technical scope disclosed by the present invention, which should be covered by the scope of protection of the present invention.

Claims

1. A VSG frequency modulation control method for grid-type energy storage in a wind-storage system, characterized in that: The method comprises: Obtain the topology of the wind-storage system; Based on the topological structure of the wind-storage system, a control structure of the network subsystem is obtained; Based on the networking subsystems, obtaining a mathematical model of each of the networking subsystems; Based on the mathematical model of the networking subsystem, key parameters of the networking frequency modulation are obtained; Based on the key parameters of the network frequency modulation, VSG frequency modulation control is performed on the network, including: Establish a network frequency modulation frequency and a key parameter equation group of the network frequency modulation, the equation group is: when hour ； when hour ； ； described Δf Indicates the network frequency modulation frequency, 、 are the initial values ​​of J and D, is the derivative of the system frequency, 、 are the thresholds of J and D changes, that is, when When it is less than the threshold, the system frequency can be considered to have reached a steady state. 、 are the coefficients of change of J and D, respectively, which determine the speed of change of J and D; Based on the equation group, the key coefficients of the network are adjusted to perform VSG frequency modulation control.

2. The VSG frequency modulation control method for grid-type energy storage in a wind-storage system according to claim 1 is characterized in that: The obtaining of the topological structure of the wind energy storage system includes: Obtain the composition of the wind-storage system and the connection relationship between subsystems within the network; Based on the connection relationship between the subsystems in the network, the topological structure of the wind-storage system is obtained.

3. The VSG frequency modulation control method for grid-type energy storage in a wind-storage system according to claim 1 is characterized in that: The obtaining of the control structure of the network subsystem based on the topological structure of the wind-storage system includes: Based on the topological structure of the wind-storage system, all network subsystems are obtained; Based on the role of the grid-forming subsystem in the wind-storage system, obtaining the type of the grid-forming subsystem; Based on the type and composition of the networking subsystem, obtaining a control structure of the networking subsystem; The grid-building subsystem includes an energy storage system, a thermal power system, and a wind power system.

4. The VSG frequency modulation control method for grid-type energy storage in a wind-storage system according to claim 1 is characterized in that: The acquiring of the mathematical model of each of the networking subsystems based on the control structure of the networking subsystems includes: Based on the control structure of the networking subsystem, obtaining a control block diagram of the networking subsystem; Based on the control block diagram of the networking subsystem, a mathematical model of each networking subsystem is obtained.

5. The VSG frequency modulation control method for grid-type energy storage in a wind-storage system according to claim 4 is characterized in that: The obtaining of mathematical models of the respective networking subsystems based on the control block diagram of the networking subsystems includes: Based on the control block diagram of the grid-forming subsystem, obtaining control block diagrams of the energy storage system, the thermal power system, and the wind power system; Based on the control block diagram of the grid-forming subsystem, among the mathematical models of the various grid-forming subsystems obtained, the mathematical model of the energy storage system is: ； in, is the VSG frequency modulation coefficient; , is the grid connection point voltage, G 1 Indicates the frequency modulation coefficient gain; is the inverter output electromotive force, is the VSG output line impedance; s is a variable in the complex frequency domain; D represents the damping coefficient; J is the moment of inertia; ω 0 represents the cutoff frequency; P b Represents the output of the energy storage system; Δf Indicates the network frequency modulation frequency; G b ( s ) represents the energy storage equivalent transfer function; The mathematical model of the thermal power system is: ； in, is the speed regulator action time constant; is the reheater time constant; is the time constant of the main steam inlet chamber; is the high-pressure turbine mechanical torque; F RH represents the high-pressure turbine reheat mechanical torque; K g Expressed as the frequency regulation coefficient of thermal power units; P g Indicates the inertia response output power of the thermal power unit; Represents the equivalent transfer function of the thermal power unit.

6. The VSG frequency modulation control method for grid-type energy storage in a wind-storage system according to claim 4 is characterized in that: Also includes: Based on the energy storage system and the wind power system, a mathematical model of the wind-storage system is obtained. The mathematical model of the wind-storage system is: ； in, H sys represents the inertia of the wind-storage system; D sys represents the damping coefficient of the wind storage system; ΔP L ( s ) represents load disturbance; Δf ( s ) represents the frequency of the networking system.

7. The VSG frequency modulation control method for grid-type energy storage in a wind-storage system according to claim 1, characterized in that: The obtaining of key parameters of network frequency modulation based on the mathematical model of the network subsystem includes: Based on the mathematical model of the grid subsystem, a mathematical model of the wind energy storage system is obtained; Based on the mathematical model of the wind-storage system, obtaining simulation results; Based on the simulation results, key parameters of network frequency modulation are obtained; The key parameters include moment of inertia and damping coefficient.

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