New energy power station rapid power adaptive control method and system based on short circuit ratio distribution

Abstract

The invention discloses a new energy power station rapid power adaptive control method and system based on short-circuit ratio distribution, and the method comprises the steps: introducing an adaptive droop coefficient, a dynamic virtual inertia, a virtual capacitance adaptive rate and an adaptive damping coefficient, and dynamically adjusting a control parameter according to the short-circuit ratio of a power grid system; and the problems of frequency collapse in a weak power grid and excessive response in a strong power grid are effectively solved. Meanwhile, the robustness of the power grid system is optimized by adopting a superhelix observer and an integral sliding mode controller. The system comprises a droop control module, a dynamic virtual inertia adjustment module, an oscillation adjustment module and a robustness optimization module, realizes optimal power adjustment under different power grid intensities, and significantly improves the power adaptive capability of a new energy power station and the overall stability of a power grid system. Simulation results show that the method can effectively stabilize power fluctuation and improve the frequency and power stability of a power system.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy power stations, and in particular to a method and system for rapid power adaptive control of a new energy power station based on short-circuit ratio distribution. Background Art

[0002] With the large-scale integration of distributed energy sources such as photovoltaics and wind power into the power grid, the power system is characterized by a high proportion of power electronics. The proportion of traditional synchronous generators has decreased, system inertia has weakened, and frequency stability has become challenging. Virtual synchronous generators (VSGs) provide frequency support by simulating the inertia and damping characteristics of synchronous generators, but their control performance is significantly affected by grid strength. Short-circuit ratio (SCR), a core indicator of grid strength, is defined as the ratio of the grid's short-circuit capacity to the rated capacity of the VSG.

[0003] Existing VSG control technology has the following drawbacks: Fixed parameter control limitations: The active frequency loop parameters of traditional VSGs (such as virtual inertia J and damping coefficient D) are fixed and cannot adapt to differences in grid strength caused by changes in SCR. In weak grids (low SCR), insufficient system inertia can easily lead to frequency collapse; in strong grids (high SCR), fixed parameters can cause over-response and oscillation. Lack of reference active power optimization: The existing VSG reference active power is calculated only based on frequency deviation and does not introduce SCR factors, making it difficult to achieve optimal power regulation under different grid strengths. Summary of the Invention

[0004] The purpose of the present invention is to provide a new energy power station fast power adaptive control method and system based on short circuit ratio distribution, so as to solve the problem that the control performance of traditional VSG is limited when the grid strength changes.

[0005] To achieve the above object, the technical solution provided by the present invention is:

[0006] A fast power adaptive control method for a new energy power station based on short-circuit ratio distribution, characterized by:

[0007] An adaptive droop coefficient is introduced into the grid system control of the new energy power station. The adaptive droop coefficient dynamically changes according to the short-circuit ratio of the grid system to adjust the grid system frequency.

[0008] Dynamic virtual inertia is also introduced into the power grid system control. The dynamic virtual inertia is increased or decreased according to the difference between weak and strong power grids to adjust the size of the inertial response. The dynamic virtual inertia is adjusted according to the change of the short-circuit ratio to obtain an adaptive virtual inertia. The value of the adaptive virtual inertia is changed according to the rate of change of the power grid system frequency.

[0009] A virtual capacitor adaptation rate is also introduced into the grid system control. The virtual capacitor adaptation rate increases when the grid power changes faster, providing power support to stabilize the voltage. An adaptive damping coefficient is also introduced. The virtual capacitor adaptation rate and the adaptive damping coefficient are complementary controlled to suppress voltage oscillations. The adaptive damping coefficient value is increased when the deviation of the grid system frequency exceeds a set threshold.

[0010] In the power frequency controller of the power grid system, a super helix observer is used to detect the frequency and uncertain disturbance of the power grid system, and the detection value of the super helix observer is controlled by an integral sliding mode controller to optimize the robustness of the power grid system.

[0011] To optimize the above technical solutions, specific measures / limitations adopted also include:

[0012] The adaptive droop coefficient K p The control formula of (SCR) is as follows:

[0013]

[0014] Where Kp is the frequency variation coefficient; SCR represents the reference short-circuit ratio, which is taken as a fixed value in the power grid and recorded as SCR0; α and β represent the rate at which the control droop coefficient changes with SCR, respectively, and are determined through system identification.

[0015] When the SCR increases, the adaptive droop coefficient automatically decreases to avoid excessive frequency regulation response when power changes; when the SCR decreases, the adaptive droop coefficient automatically increases to enhance the frequency regulation capability.

[0016] Furthermore, the expression of the dynamic virtual inertia J(SCR) is:

[0017] J(SCR)=J0·e -λ(SCR-1)

[0018] Where J0 is the virtual inertia reference value, and λ is the virtual inertia adjustment factor, which is related to the system time constant;

[0019] In a weak power grid, dynamic virtual inertia is increased to improve the system inertia response; in a strong power grid, dynamic virtual inertia is reduced to reduce control delay.

[0020] Furthermore, the dynamic virtual inertia is adjusted according to the change of the short-circuit ratio to obtain the adaptive virtual inertia J, which is expressed as follows:

[0021]

[0022] Where, γ represents the frequency change response coefficient, |df / dt| represents the frequency change rate, and f th The threshold value indicating the rate of change of frequency;

[0023] When the frequency change rate exceeds the threshold, the adaptive virtual inertia J increases to suppress the sudden change of frequency.

[0024] Furthermore, the expression of the virtual capacitance adaptation rate Cv is:

[0025]

[0026] Where, k1 is the introduced power variation coefficient, k2 is the introduced voltage variation coefficient, V dc Indicates DC voltage, V dc0 represents the initial DC voltage, Indicates the power change rate, C v0 represents the initial virtual capacitance;

[0027] When power changes rapidly, the virtual capacitor adaptation rate Cv increases to provide instantaneous power support for the system; when the DC voltage deviates from the rated value, the virtual capacitor adaptation rate Cv is dynamically adjusted to enhance voltage stability.

[0028] The expression of the adaptive damping coefficient D is:

[0029]

[0030] Where D0 represents the initial damping coefficient, represents the frequency deviation correlation coefficient, ω represents the actual angular frequency, ω0 represents the rated angular frequency, and η represents the dependence coefficient of the introduced adjustment damping on the virtual capacitance;

[0031] When the frequency deviation of the power grid system is large, the adaptive damping coefficient D is enhanced to suppress oscillation, and is controlled complementary to the virtual capacitor adaptive rate Cv.

[0032] Furthermore, the frequency and indeterminate disturbance of the power grid system are detected by the super spiral observer in the power frequency controller of the power grid system. ref expression:

[0033]

[0034] In the formula, P0 represents the reference active value, f0 represents the system rated frequency, f represents the system actual frequency, SCR represents the reference short-circuit ratio, and in the power grid, a fixed value is taken as the reference short-circuit ratio, which is recorded as SCR0. Indicates the rate of change of angular frequency.

[0035] Furthermore, the integral sliding mode controller is expressed as follows:

[0036]

[0037] Where z1, z2, and z3 are observer states, representing the estimated system frequency deviation △w, the frequency deviation derivative, and and the system uncertain disturbance a(t), λ1, λ2, and λ3 are the observer gains, sign(e) represents the sign function that outputs its sign according to the value of the observation error e, J represents the virtual moment of inertia, T represents the inertia time constant, e=z1-x1 is the observation error, and α is the additional signal added in the power frequency controller, which is also the control input of the system.

[0038] Furthermore, in the integral sliding mode controller, the synthetic control law u(t)=u eq +u sw Control the detection value of the super spiral observer, where u eq is the equivalent control of the sliding mode controller, u sw The switching control of the sliding mode controller compensates for the disturbance estimation error. The specific control process includes:

[0039] Equivalent control: When the system is on the sliding surface, s = 0 and s is the integral sliding surface, ignoring the disturbance estimation error, the equivalent control u eq for

[0040]

[0041] Switching control: To compensate for disturbance estimation errors Introducing the switch item u sw :

[0042]

[0043] Combining equivalent control with switching control and using the observer output z3 to replace a(t), we get:

[0044] u(t)=u eq +u sw

[0045] =JT(-cx2-kx1-z3)-JTηsat(s / φ)

[0046] Where c and k are variable constants, c determines the state convergence speed, and k adjusts the strength of the integral action; η and φ are switching gains, and η must satisfy η>|a(t)-z3| max , φ controls the boundary layer thickness; x1 represents the system frequency deviation △w, and x2 represents the frequency deviation derivative a(t) represents the system's indeterminate disturbance, P t Indicates mechanical power, P n Indicates the measured active power, P erepresents the electromagnetic power, and sat(s / φ) represents the boundary layer saturation function.

[0047] The present invention also provides a new energy power station fast power adaptive control system based on short-circuit ratio distribution, comprising:

[0048] A droop control module, wherein the droop control module uses an adaptive droop coefficient to adjust the frequency of the power grid system according to the dynamic change of the short-circuit ratio of the power grid system;

[0049] A dynamic virtual inertia adjustment module, wherein the dynamic virtual inertia is increased or decreased according to the difference between weak and strong power grids to adjust the magnitude of the inertial response; the dynamic virtual inertia is adjusted according to the change of the short-circuit ratio to obtain an adaptive virtual inertia, and the value of the adaptive virtual inertia is changed according to the rate of change of the power grid system frequency;

[0050] The oscillation regulation module includes a virtual capacitor adaptive rate regulation module and a damping coefficient regulation module. The virtual capacitor adaptive rate regulation module increases the virtual capacitor adaptive rate when the grid power changes faster, providing power support to stabilize the voltage. The damping coefficient regulation module increases the adaptive damping coefficient when the grid system frequency deviation exceeds a set threshold. The virtual capacitor adaptive rate and the damping coefficient are complementary controlled to suppress voltage oscillations.

[0051] The robustness optimization module detects the frequency and indeterminate disturbance of the power grid system through a super spiral observer in the power frequency controller of the power grid system, and controls the detection value through an integral sliding mode controller to optimize the robustness of the power grid system.

[0052] Compared with the prior art, the present invention has the following beneficial effects:

[0053] The present invention significantly improves the adaptability of new energy power stations to changes in grid strength. By introducing an adaptive droop coefficient, dynamic virtual inertia, and adaptive virtual inertia, the present invention can dynamically adjust control parameters based on the short-circuit ratio of the power grid system, effectively avoiding frequency collapse in weak power grids and over-response in strong power grids. At the same time, the use of a dynamic reference active power expression for adaptive SCR achieves optimal power regulation under different grid strengths. In addition, through the application of a superhelical observer and an integral sliding mode controller, the present invention further optimizes the robustness of the power grid system.

[0054] The present invention significantly improves the power adaptability of the new energy power station and the overall stability of the power grid system, providing strong support for the safe and efficient operation of the power system. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1This is a flow chart of the improved reference active power and virtual capacitor adaptive control method proposed by the present invention.

[0056] Figure 2 2 is a structural diagram of a microgrid in an embodiment of the present invention.

[0057] Figure 3 This is a simulated virtual speed diagram in an embodiment of the present invention.

[0058] Figure 4 1 is a frequency curve diagram in an embodiment of the present invention.

[0059] Figure 5 1 is an active power curve diagram in an embodiment of the present invention. DETAILED DESCRIPTION

[0060] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0061] In one embodiment, the present invention proposes a method for rapid power adaptive control of a new energy power station based on short-circuit ratio distribution:

[0062] An adaptive droop coefficient is introduced into the grid system control of the new energy power station. The adaptive droop coefficient adjusts the grid system frequency according to the dynamic changes of the short-circuit ratio of the grid system.

[0063] Dynamic virtual inertia is also introduced into the power grid system control. The dynamic virtual inertia increases or decreases according to the difference between weak and strong power grids to adjust the size of the inertial response. The dynamic virtual inertia is adjusted according to the change of the short-circuit ratio to obtain an adaptive virtual inertia. The value of the adaptive virtual inertia changes according to the rate of change of the power grid system frequency.

[0064] A virtual capacitor adaptation rate is also introduced into the grid system control. The virtual capacitor adaptation rate increases when the grid power changes faster, providing power support to stabilize the voltage. An adaptive damping coefficient is also introduced. The virtual capacitor adaptation rate and the adaptive damping coefficient are complementary controlled to suppress voltage oscillations. The adaptive damping coefficient value is increased when the deviation of the grid system frequency exceeds a set threshold.

[0065] In the power frequency controller of the power grid system, a super helix observer is used to detect the frequency and uncertain disturbance of the power grid system, and the detection value of the super helix observer is controlled by an integral sliding mode controller to optimize the robustness of the power grid system.

[0066] Adaptive droop coefficient K p The control formula of (SCR) is as follows:

[0067]

[0068] When the SCR increases, the adaptive droop coefficient automatically decreases to avoid excessive frequency regulation response when power changes; when the SCR decreases, the adaptive droop coefficient automatically increases to enhance the frequency regulation capability.

[0069] In some embodiments: wherein, K p is the frequency variation coefficient, with a value of 5000; SCR represents the baseline short-circuit ratio, with SCR = 3 being the cutoff point in the power grid; α and β represent the rate at which the droop coefficient changes with SCR, with α = 0.5 and β = 2; as SCR increases, the droop coefficient automatically decreases to avoid excessive system response; as SCR decreases, the droop coefficient automatically increases to enhance frequency regulation capabilities. The innovative point of the formula is that the SCR exponentially weighted droop coefficient is introduced by (SCR0 / SCR) β The nonlinear self-adaptation of droop gain is achieved, breaking through the limitations of traditional linear adjustment. SCR, as the ratio of grid impedance to VSG capacity, directly affects the frequency response characteristics of VSG (frequency rigidity of strong grids and frequency flexibility of weak grids).

[0070] The expression of dynamic virtual inertia J(SCR) is:

[0071] J(SCR)=J0·e -λ(SCR-1)

[0072] In a weak power grid, dynamic virtual inertia is increased to improve the system inertia response; in a strong power grid, dynamic virtual inertia is reduced to reduce control delay.

[0073] In the formula, J0 is the virtual inertia baseline value, and λ is the virtual inertia adjustment factor, which is related to the system time constant. λ is initially set to 1 and reduced to 0.7 in weak grids. This factor is also related to the system time constant. In weak grids, the virtual inertia is automatically increased to improve the system's inertial response; in strong grids, the virtual inertia is appropriately reduced to reduce control delay. The above formula simulates the exponential decay of synchronous motor inertia with grid strength, which conforms to the physical laws of actual grids.

[0074] According to the change of short-circuit ratio, the dynamic virtual inertia is adjusted to obtain the adaptive virtual inertia J, which is expressed as follows:

[0075]

[0076] Where, γ represents the frequency change response coefficient, |df / dt| represents the frequency change rate, and f th The threshold value indicating the rate of change of frequency;

[0077] When the frequency change rate exceeds the threshold, the adaptive virtual inertia J increases to suppress the sudden change of frequency.

[0078] The expression of virtual capacitance adaptation rate Cv is:

[0079]

[0080] Where, k1 is the introduced power variation coefficient, k2 is the introduced voltage variation coefficient, V dc Indicates DC voltage, V dc0 represents the initial DC voltage, Indicates the power change rate, C v0 Represents the initial virtual capacitance; when the power changes rapidly, the virtual capacitance adaptation rate C v Increase, provide instantaneous power support for the system; when the DC voltage deviates from the rated value, the virtual capacitor adaptive rate C v Perform dynamic adjustments to enhance voltage stability.

[0081] In some embodiments, C v0 =1000μF, set K1 = 1. When a sudden load occurs, increase K1 to 2. When K2 = 0.5, increase K2 to 1 in weak grid conditions. When power changes rapidly, Cv increases, providing instantaneous power support for the system. When the DC voltage deviates from the rated value, dynamic adjustments are made to enhance voltage stability. By incorporating the DC-side capacitor energy storage in the power electronics interface into the VSG model, the introduction of virtual capacitors can compensate for the system's limited dynamic response and harmonic suppression capabilities during rapid load changes or grid faults. Providing an additional energy storage path improves the system's dynamic response speed and optimizes the VSG's harmonic characteristics.

[0082] The expression of the adaptive damping coefficient D is:

[0083]

[0084] Where D0 represents the initial damping coefficient, represents the frequency deviation correlation coefficient, ω represents the actual angular frequency, ω0 represents the rated angular frequency, and η represents the dependence coefficient of the introduced adjustment damping on the virtual capacitance;

[0085] When the frequency deviation of the power grid system is large, the adaptive damping coefficient D is enhanced to suppress oscillation, and is controlled complementary to the virtual capacitor adaptive rate Cv.

[0086] In some embodiments, wherein is the initial value. If the system experiences low-frequency oscillation, increase To 400. The initial value η=30. If the damping is excessive, reduce η to 20. D0=100 The improved adaptive damping enhances damping when the frequency deviation is large, suppresses oscillation, and complements the virtual capacitor control.

[0087] The frequency and indeterminate disturbance of the power grid system are detected by super spiral observer in the power frequency controller of the power grid system. The following dynamic reference active power P of the adaptive SCR is adopted ref expression:

[0088]

[0089] In the formula, P0 represents the reference active value, f0 represents the system rated frequency, f represents the system actual frequency, SCR represents the reference short-circuit ratio, and in the power grid, a fixed value is taken as the reference short-circuit ratio, which is recorded as SCR0. Indicates the rate of change of angular frequency.

[0090] The integral sliding mode controller expression is as follows:

[0091]

[0092] Define the error variable:

[0093]

[0094] By taking the derivative of the error and combining it with the original system equation, we can get the error dynamic equation:

[0095]

[0096] In the design of the sliding mode superhelical observer, high-precision estimation of system state and unknown disturbances is achieved by constructing third-order dynamic equations.

[0097] According to the superhelical algorithm theory, the gain must satisfy:

[0098]

[0099] Then there exists a finite time t f , so that e1=e2=e3=0 for t≥t f holds, that is, the observer state accurately tracks the true state and disturbance.

[0100] The specific gain selection is as follows:

[0101]

[0102] The upper bound of the perturbation derivative is L = 100 N / s, then:

[0103]

[0104] Where z1, z2, and z3 are observer states, representing the estimated system frequency deviation △w, the frequency deviation derivative, and and the system uncertain disturbance a(t), λ1, λ2, and λ3 are the observer gains, sign(e) represents the sign function that outputs its sign according to the value of the observation error e, J represents the virtual moment of inertia, T represents the inertia time constant, e=z1-x1 is the observation error, and α is the additional signal added in the power frequency controller, which is also the control input of the system.

[0105] In the integral sliding mode controller, the synthetic control law u(t) = u eq +u sw Control the detection value of the super spiral observer, where u eq is the equivalent control of the sliding mode controller, u sw The switching control of the sliding mode controller compensates for the disturbance estimation error. The specific control process includes:

[0106] The observation value is controlled and an integral sliding surface is designed to eliminate the steady-state error. The integral sliding surface formula is as follows:

[0107]

[0108] Equivalent control design, when the system is on the sliding surface (s=0 and ), ignoring the disturbance estimation error, the equivalent control u eq satisfy:

[0109]

[0110] Equivalent control: When the system is on the sliding surface, s = 0 and s is the integral sliding surface, ignoring the disturbance estimation error, the equivalent control u eq for

[0111]

[0112] Switching control: To compensate for disturbance estimation errors Introducing the switch item u sw :

[0113]

[0114] Combining equivalent control with switching control and using the observer output z3 to replace a(t), we get:

[0115] u(t)=u eq +u sw

[0116] =JT(-cx2-kx1-z3)-JTηsat(s / φ)

[0117] Where c and k are variable constants, c determines the state convergence speed, and k adjusts the strength of the integral action; η and φ are switching gains, and η must satisfy η>|a(t)-z3| max , φ controls the boundary layer thickness; x1 represents the system frequency deviation △w, and x2 represents the frequency deviation derivative a(t) represents the system's indeterminate disturbance, P t Indicates mechanical power, P n Indicates the measured active power, P e represents the electromagnetic power, and sat(s / φ) represents the boundary layer saturation function.

[0118] In some embodiments, the proportional coefficient c determines the state convergence speed and is set to c=2-5; the integral gain k adjusts the strength of the integral action to suppress steady-state error and avoid oscillation caused by excessive integration and is set to k=0.5-1; the switching gain η must satisfy η>|a(t)-z3| max , covering the observer estimation error, take φ controls the boundary layer thickness to balance buffeting suppression and tracking accuracy, and takes φ = 0.1~0.5.

[0119] In another embodiment, the present invention proposes a new energy power station fast power adaptive control system based on short-circuit ratio distribution, comprising:

[0120] A droop control module uses an adaptive droop coefficient to adjust the frequency of the power grid system according to the dynamic changes of the short-circuit ratio of the power grid system;

[0121] Dynamic virtual inertia adjustment module: This module increases or decreases dynamic virtual inertia for weak and strong grids to adjust the inertia response. It also adjusts the dynamic virtual inertia based on changes in the short-circuit ratio to obtain an adaptive virtual inertia. The adaptive virtual inertia value is changed based on the rate of change of the grid system frequency.

[0122] The oscillation regulation module includes a virtual capacitor adaptive rate regulation module and a damping coefficient regulation module. In the virtual capacitor adaptive rate regulation module, the virtual capacitor adaptive rate is increased when the grid power changes rapidly, providing power support to stabilize the voltage. In the damping coefficient regulation module, the adaptive damping coefficient value is increased when the deviation of the grid system frequency exceeds a set threshold. The virtual capacitor adaptive rate and the damping coefficient are complementary controlled to suppress voltage oscillations.

[0123] Robustness optimization module,The robustness optimization module detects the frequency and uncertain disturbance of the power grid system through a super-helical observer in the power frequency controller of the power grid system, and controls the detection value through an integral sliding mode controller to optimize the robustness of the power grid system.

[0124] The technical solution of the present invention is further described in detail below with reference to specific embodiments. Figure 1 As shown, in some embodiments, the method steps are as follows:

[0125] S1: Acquire the short-circuit ratio data of the power grid system in the renewable energy power station and introduce an adaptive droop coefficient. This coefficient is dynamically adjusted according to the changes in the short-circuit ratio of the power grid system in the renewable energy power station. When the short-circuit ratio increases, the droop coefficient automatically decreases to avoid excessive frequency regulation response when power changes. When the short-circuit ratio decreases, the droop coefficient automatically increases to enhance frequency regulation capability.

[0126] S2: Dynamic virtual inertia is introduced into the power grid system control. In a weak power grid, the virtual inertia is automatically increased to improve the system inertia response; in a strong power grid, the virtual inertia is automatically reduced to reduce control delay.

[0127] S3: Introducing the virtual capacitor adaptive rate into the power grid system control. When the power changes rapidly, the virtual capacitor Cv increases, providing instantaneous power support for the power grid system in the new energy power station.

[0128] S4: Inherits the adaptive short-circuit ratio characteristics of the power grid system in the new energy power station and adaptively improves the virtual inertia to obtain an adaptive virtual inertia. When the frequency change rate of the power grid system exceeds the threshold, the inertia is automatically increased to suppress sudden frequency changes.

[0129] S5: Introducing and improving the damping coefficient in the power grid system control. The improved adaptive damping enhances damping when the frequency deviation is large to suppress oscillation and forms a complementary control with the virtual capacitor.

[0130] S6: Introduce sliding mode control in power grid system control, design super spiral observer, and detect system frequency and uncertain disturbances;

[0131] S7: Construct a sliding surface, control the observed values, and design an integral sliding mode controller to synthesize the control law to control the values ​​observed by the superhelical observer; the controller consists of two parts: equivalent control and switching control. Equivalent control is used to realize the sliding of the system state on the sliding surface, and switching control is used to compensate for the disturbance estimation error to ensure the robustness of the system.

[0132] like Figure 2 As shown in the figure, the new energy power station, as the source of electric energy, converts the electric energy into alternating current through a DC / AC converter. The converted alternating current is then transmitted to the large power grid. The large power grid, as the main receiving end of the power network, is responsible for distributing the electric energy to various load points.

[0133] like Figure 3As shown, the dynamic response of the virtual speed in the simulation process in the embodiment of the present invention can be seen. When the system is disturbed, such as load changes, the virtual speed will change. However, under the control method of the present invention, the virtual speed can quickly return to a stable state, indicating that the control method proposed in the present invention has good frequency response characteristics and stability.

[0134] like Figure 4 As shown in the simulation, when the system is disturbed, such as by rapid changes in the power of a renewable energy power station, the frequency fluctuates. However, under the control method of the present invention, the frequency can quickly recover to near the rated value, with a smaller fluctuation range and a faster recovery speed. This demonstrates that the control method proposed in the present invention can effectively improve the frequency stability of the power system and suppress frequency fluctuations.

[0135] like Figure 5 As shown in the figure, it can be seen that during the simulation process, when the system is disturbed, such as load switching or grid failure, the active power will fluctuate. However, under the control method of the present invention, the active power can quickly return to a stable state with a smaller fluctuation range. This shows that the control method proposed by the present invention can effectively smooth out power fluctuations and improve the power stability of the power system. At the same time, through the introduction of virtual capacitors and the application of adaptive control strategies, the present invention can also optimize the harmonic characteristics of VSG and improve the power quality of the power system.

[0136] The above description is only a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Any simple modification, equivalent replacement and improvement made by any technician familiar with the profession to the above embodiment without departing from the scope of the technical solution of the present invention and based on the technical essence of the present invention shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A fast power adaptive control method for a new energy power station based on short-circuit ratio distribution, characterized by: An adaptive droop coefficient is introduced into the grid system control of the new energy power station. The adaptive droop coefficient dynamically changes according to the short-circuit ratio of the grid system to adjust the grid system frequency. Dynamic virtual inertia is also introduced into the power grid system control. The dynamic virtual inertia is increased or decreased according to the difference between weak and strong power grids to adjust the size of the inertial response. The dynamic virtual inertia is adjusted according to the change of the short-circuit ratio to obtain an adaptive virtual inertia. The value of the adaptive virtual inertia is changed according to the rate of change of the power grid system frequency. A virtual capacitor adaptation rate is also introduced into the grid system control, and the virtual capacitor adaptation rate increases when the grid power changes faster; and an adaptive damping coefficient is introduced, and the virtual capacitor adaptation rate and the adaptive damping coefficient are complementary controlled, and the value of the adaptive damping coefficient is increased when the deviation of the grid system frequency exceeds a set threshold; In the power frequency controller of the power grid system, the frequency and the indeterminate disturbance of the power grid system are detected by a super spiral observer, and the detection value of the super spiral observer is controlled by an integral sliding mode controller.

2. The method for rapid power adaptive control of a new energy power station based on short-circuit ratio distribution according to claim 1 is characterized in that: The adaptive droop coefficient K p The control formula of (SCR) is as follows: Where Kp is the frequency variation coefficient; SCR represents the reference short-circuit ratio, which is taken as a fixed value in the power grid and recorded as SCR0; α and β represent the rate at which the control droop coefficient changes with SCR, respectively, and are determined through system identification. When the SCR increases, the adaptive droop coefficient automatically decreases; when the SCR decreases, the adaptive droop coefficient automatically increases.

3. The method for rapid power adaptive control of a new energy power station based on short-circuit ratio distribution according to claim 1 is characterized in that: The expression of the dynamic virtual inertia J(SCR) is: J(SCR)=J0·e -λ(SCR-1) Where J0 is the virtual inertia reference value, and λ is the virtual inertia adjustment factor, which is related to the system time constant; Increase the dynamic virtual inertia in a weak power grid; reduce the dynamic virtual inertia in a strong power grid.

4. The method for rapid power adaptive control of a new energy power station based on short-circuit ratio distribution according to claim 1 is characterized in that: The dynamic virtual inertia is adjusted according to the change of the short-circuit ratio to obtain the adaptive virtual inertia J, which is expressed as follows: Where, γ represents the frequency change response coefficient, |df / dt| represents the frequency change rate, and f th The threshold value indicating the rate of change of frequency; When the frequency change rate exceeds a threshold, the adaptive virtual inertia J increases.

5. The method for rapid power adaptive control of a new energy power station based on short-circuit ratio distribution according to claim 1 is characterized in that: The virtual capacitance adaptation rate C v The expression is: Where, k1 is the introduced power variation coefficient, k2 is the introduced voltage variation coefficient, V dc Indicates DC voltage, V dc0 represents the initial DC voltage, Indicates the power change rate, C v0 represents the initial virtual capacitance; When the power changes rapidly, the virtual capacitor adaptation rate C v Increase; when the DC voltage deviates from the rated value, the virtual capacitance adaptive rate C v Make dynamic adjustments.

6. The method for rapid power adaptive control of a new energy power station based on short-circuit ratio distribution according to claim 1, characterized in that: The expression of the adaptive damping coefficient D is: Where D0 represents the initial damping coefficient, represents the frequency deviation correlation coefficient, ω represents the actual angular frequency, ω0 represents the rated angular frequency, and η represents the dependence coefficient of the introduced adjustment damping on the virtual capacitance; When the frequency deviation of the power grid system is large, the adaptive damping coefficient D is enhanced, and the virtual capacitor adaptive rate C v Complementary control.

7. The method for rapid power adaptive control of a new energy power station based on short-circuit ratio distribution according to claim 1 is characterized in that: The power frequency controller of the power grid system detects the frequency and the indeterminate disturbance of the power grid system through the super spiral observer, and adopts the following adaptive SCR dynamic reference active power P ref expression: In the formula, P0 represents the reference active value, f0 represents the system rated frequency, f represents the system actual frequency, SCR represents the reference short-circuit ratio, and in the power grid, a fixed value is taken as the reference short-circuit ratio, which is recorded as SCR0. Indicates the rate of change of angular frequency.

8. The method for rapid power adaptive control of a new energy power station based on short-circuit ratio distribution according to claim 1 is characterized in that: The integral sliding mode controller expression is as follows: Where z1, z2, and z3 are observer states, representing the estimated system frequency deviation △w, the frequency deviation derivative, and and the system uncertain disturbance a(t), λ1, λ2, and λ3 are the observer gains, sign(e) represents the sign function that outputs the sign according to the value of the observation error e, J represents the virtual moment of inertia, T represents the inertia time constant, e=z1-x1 is the observation error, and α is the control input of the power frequency controller.

9. The method for rapid power adaptive control of a new energy power station based on short-circuit ratio distribution according to claim 1, characterized in that: In the integral sliding mode controller, the synthetic control law u(t)=u eq +u sw Control the detection value of the super spiral observer, where u eq is the equivalent control of the sliding mode controller, u sw The switching control of the sliding mode controller compensates for the disturbance estimation error. The specific control process includes: Equivalent control: When the system is on the sliding surface, s = 0 and s is the integral sliding surface, ignoring the disturbance estimation error, the equivalent control u eq for Switching control: To compensate for disturbance estimation errors Introducing the switch item u sw : Combining equivalent control with switching control and using the observer output z3 to replace a(t), we get: u(t)=u eq +u sw =JT(-cx2-kx1-z3)-JTηsat(s / φ) Where c and k are variable constants, c determines the state convergence speed, and k adjusts the strength of the integral action; η and φ are switching gains, and η must satisfy η>|a(t)-z3| max , φ controls the boundary layer thickness; x1 represents the system frequency deviation △w, and x2 represents the frequency deviation derivative a(t) represents the system's indeterminate disturbance, P t Indicates mechanical power, P n Indicates the measured active power, P e represents the electromagnetic power, and sat(s / φ) represents the boundary layer saturation function.

10. A new energy power station fast power adaptive control system based on short circuit ratio distribution, characterized in that: include: A droop control module, wherein the droop control module uses an adaptive droop coefficient to adjust the frequency of the power grid system according to the dynamic change of the short-circuit ratio of the power grid system; A dynamic virtual inertia adjustment module, wherein the dynamic virtual inertia is increased or decreased according to the difference between weak and strong power grids to adjust the magnitude of the inertial response; the dynamic virtual inertia is adjusted according to the change of the short-circuit ratio to obtain an adaptive virtual inertia, and the value of the adaptive virtual inertia is changed according to the rate of change of the power grid system frequency; The oscillation regulation module includes a virtual capacitor adaptive rate regulation module and a damping coefficient regulation module; the virtual capacitor adaptive rate regulation module increases the virtual capacitor adaptive rate when the grid power changes faster; the damping coefficient regulation module increases the adaptive damping coefficient when the grid system frequency deviation exceeds a set threshold; the virtual capacitor adaptive rate and the damping coefficient are controlled in a complementary manner; The robustness optimization module detects the frequency and indeterminate disturbance of the power grid system through a super spiral observer in the power frequency controller of the power grid system, and controls the detection value through an integral sliding mode controller.

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