Method for enhancing stability of optical storage grid-connected system and related equipment

Abstract

The embodiment of the invention discloses a method for enhancing the stability of an optical storage grid-connected system and related equipment, and the method comprises the steps: dynamically adjusting a rotational inertia steady-state value of the optical storage grid-connected system through an angular frequency change rate and an angular frequency change amount, and carrying out the dynamic self-adaption adjustment of inertia according to the actual operation state of the optical storage grid-connected system; the sudden change of the rotational inertia caused by the sudden change of the angular velocity is avoided, and the stability and the response performance of the optical storage grid-connected system are improved. Meanwhile, the anti-interference performance and the robustness of the optical storage grid-connected system are enhanced through active disturbance rejection control, so that the optical storage grid-connected system can quickly recover to a steady state when facing various disturbances, overshoot and oscillation are reduced, and the stability and the reliability of the optical storage grid-connected system are improved.

Description

[Technical field]

[0001] The present invention relates to the field of new energy grid-connected technology, and in particular to a method for enhancing the stability of a photovoltaic energy storage grid-connected system and related equipment. [Background technology]

[0002] Renewable energy generation is gradually replacing traditional fossil fuel power generation. However, most new energy sources are connected to the grid through power electronic converters, showing the characteristics of "low inertia and weak damping", which brings challenges to the stable operation of the power grid. After adopting virtual synchronous generator (VSG) control, the new energy power generation system can simulate the dynamic characteristics of the synchronous generator, give the converter inertia and damping, and have the frequency regulation characteristics and voltage regulation characteristics of the synchronous generator. However, under the traditional VSG control technology, the equivalent inertia and damping of the new energy power generation system are mostly constant values, which makes it difficult to maintain the stability of the grid-connected system when dealing with disturbances in different situations. In addition, the traditional VSG grid-connected system also has the problem of insufficient anti-interference ability, especially when the voltage drops due to power system faults, the traditional VSG system is prone to instability. [Summary of the invention]

[0003] In view of this, the present invention provides a method for enhancing the stability of a photovoltaic energy storage grid-connected system and related equipment.

[0004] The specific technical solution of the first embodiment of the present invention is: a method for enhancing the stability of a photovoltaic-storage grid-connected system, the method comprising: dynamically adjusting the steady-state value of the moment of inertia of the photovoltaic-storage grid-connected system according to the angular frequency change rate and angular frequency change amount of the photovoltaic-storage grid-connected system to obtain an adaptive equivalent inertia; the active power-frequency control loop of the photovoltaic-storage grid-connected system uses the adaptive equivalent inertia to control the photovoltaic-storage grid-connected system to enhance the stability of the photovoltaic-storage grid-connected system.

[0005] Preferably, the method of dynamically adjusting the steady-state value of the moment of inertia of the photovoltaic energy storage grid-connected system according to the angular frequency change rate and the angular frequency change amount of the photovoltaic energy storage grid-connected system to obtain an adaptive equivalent inertia includes: obtaining a preset rotational inertia threshold of the photovoltaic energy storage grid-connected system; when the angular frequency change rate is less than or equal to the preset rotational inertia threshold, the adaptive equivalent inertia is the steady-state value of the moment of inertia; when the angular frequency change rate is greater than the preset rotational inertia threshold, adjusting the steady-state value of the moment of inertia according to a hyperbolic tangent function, the first-order inertia link of the photovoltaic energy storage grid-connected system, the angular frequency change rate and the angular frequency change amount to obtain the adaptive equivalent inertia.

[0006] Preferably, the adaptive equivalent inertia is obtained using the following formula:

[0007]

[0008] Wherein, J is the adaptive equivalent inertia, J0 is the steady-state value of the moment of inertia, s(x) is the hyperbolic tangent function, is the first-order inertia link of the photovoltaic energy storage grid-connected system, ω is the angular frequency of the photovoltaic energy storage grid-connected system, is the angular frequency change rate, Δω is the angular frequency change amount, G is the preset rotational inertia threshold, x is the angular frequency change rate, and k, k1 and k2 are constants.

[0009] Preferably, the method further includes: obtaining the compensation torque of the photovoltaic-storage-grid-connected system according to the angular frequency of the photovoltaic-storage-grid-connected system and a preset reference angular frequency; and superimposing the compensation torque into the torque command of the active-frequency control loop.

[0010] Preferably, the method of obtaining the compensation torque of the photovoltaic energy storage grid-connected system based on the angular frequency of the photovoltaic energy storage grid-connected system and a preset reference angular frequency includes: using a first-order differential tracker to filter and derive the reference angular frequency to obtain a first tracking signal of the reference angular frequency; performing a second-order nonlinear extended state observation on the angular frequency to obtain a second tracking signal and a disturbance observation value of the angular frequency; and performing nonlinear state error feedback based on the first tracking signal, the second tracking signal and the disturbance observation value to obtain the compensation torque.

[0011] Preferably, the compensation torque is obtained using the following formula:

[0012]

[0013] Wherein, e and e1 are error signals in the second-order nonlinear extended state observation, e2 is the tracking signal of the nonlinear state error feedback, z1 is the second tracking signal, z2 is the disturbance observation value, is the time derivative of z1, is the time derivative of z2, ω is the angular frequency, β1 and β2 are the error correction gains of the second-order nonlinear extended state observation, and f al is a continuous power function with linear segments, α1 is the tracking factor of the second-order nonlinear extended state observation, α2 is the tracking factor of the nonlinear state error feedback, γ1 is the filter factor of the second-order nonlinear extended state observation, γ2 is the filter factor of the nonlinear state error feedback, b0 is the compensation factor, u(t) is the compensation torque, v1 is the first tracking signal, u0(t) is the nonlinear error feedback control quantity, and k is the regulator gain.

[0014] Preferably, the first tracking signal is obtained using the following formula:

[0015]

[0016] Wherein, e0 is the error signal of the first-order differential tracker, ω0 is the reference angular frequency, v1 is the first tracking signal, r0 is the velocity factor, α0 is the tracking factor of the first-order differential tracker, γ0 is the filter factor of the first-order differential tracker, and f al is a continuous power function with linear segments.

[0017] The specific technical solution of the second embodiment of the present invention is: a photovoltaic-storage grid-connected system stability enhancement system, the system comprising: an equivalent inertia acquisition module and an adaptive control module; the equivalent inertia acquisition module is used to dynamically adjust the steady-state value of the rotational inertia of the photovoltaic-storage grid-connected system according to the angular frequency change rate and angular frequency change amount of the photovoltaic-storage grid-connected system to obtain an adaptive equivalent inertia; the adaptive control module is used for the active-frequency control loop of the photovoltaic-storage grid-connected system to control the photovoltaic-storage grid-connected system using the adaptive equivalent inertia to enhance the stability of the photovoltaic-storage grid-connected system.

[0018] The specific technical solution of the third embodiment of the present invention is: a photovoltaic energy storage grid-connected system stability enhancement device, including a memory and a processor, the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of any one of the methods described in the first embodiment of the present application.

[0019] The specific technical solution of the fourth embodiment of the present invention is: a computer-readable storage medium storing a computer program, which, when executed by a processor, enables the processor to perform the steps of the method described in any one of the first embodiments of the present application.

[0020] Implementing the embodiments of the present invention will have the following beneficial effects:

[0021] The present invention dynamically adjusts the steady-state value of the moment of inertia of the photovoltaic storage grid-connected system according to the angular frequency change rate and angular frequency change amount of the photovoltaic storage grid-connected system to obtain an adaptive equivalent inertia; the active power-frequency control loop of the photovoltaic storage grid-connected system uses the adaptive equivalent inertia to control the photovoltaic storage grid-connected system to enhance the stability of the photovoltaic storage grid-connected system. Dynamically adjusting the steady-state value of the moment of inertia of the photovoltaic storage grid-connected system using the angular frequency change rate and angular frequency change amount can dynamically and adaptively adjust the inertia according to the actual operating state of the photovoltaic storage grid-connected system, avoid the sudden change of the moment of inertia caused by the sharp change of angular velocity, and improve the stability and response performance of the photovoltaic storage grid-connected system. At the same time, the self-anti-disturbance control enhances the anti-interference and robustness of the photovoltaic storage grid-connected system, so that the photovoltaic storage grid-connected system can quickly recover to a steady state when facing various disturbances, reduce overshoot and oscillation, and improve the stability and reliability of the photovoltaic storage grid-connected system.

Brief Description of the Drawings

[0022] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 A flowchart of a method for enhancing the stability of a photovoltaic energy storage grid-connected system;

[0024] Figure 2 This is a schematic diagram of the photovoltaic energy storage grid-connected system and its control;

[0025] Figure 3 is the graph of the tanh(x) function and its derivative;

[0026] Figure 4 It is the block diagram of ADRC control strategy;

[0027] Figure 5 The active power output of the system after disturbance under traditional VSG control and the proposed adaptive VSG control;

[0028] Figure 6 is the angular frequency of the system after disturbance under traditional VSG control and the proposed adaptive VSG control;

[0029] Figure 7 is the moment of inertia adaptive curve;

[0030] Figure 8 Output active power after three-phase short circuit fault under traditional VSG control and proposed adaptive VSG control;

[0031] Fig. 9 The frequency after three-phase short-circuit fault under traditional VSG control and the proposed adaptive VSG control;

[0032] Fig.10 The three-phase short-circuit current under traditional VSG control and the proposed adaptive VSG control;

[0033] Fig.11 It is a structural schematic diagram of a transformer winding fault area positioning system;

[0034] Fig.12 A diagram of the internal structure of a computer device;

[0035] Among them, 201 is an equivalent inertia acquisition module; 202 is an adaptive control module. [Specific implementation method]

[0036] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0037] The terms "first", "second", etc. in the specification, claims and drawings of this application are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or modules is not limited to the listed steps or modules, but optionally includes steps or modules that are not listed, or optionally includes other steps or modules that are inherent to these processes, methods, products or devices.

[0038] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0039] See also Figure 1 , is a flowchart of the steps of a method for enhancing the stability of a photovoltaic energy storage grid-connected system in the first embodiment of the present application, thereby improving the stability and response performance of the photovoltaic energy storage grid-connected system, the method comprising:

[0040] Step 101, dynamically adjusting the steady-state value of the moment of inertia of the photovoltaic-storage-grid-connected system according to the angular frequency change rate and angular frequency change amount of the photovoltaic-storage-grid-connected system to obtain an adaptive equivalent inertia;

[0041] Step 102: The active power-frequency control loop of the photovoltaic-storage-grid-connected system uses the adaptive equivalent inertia to control the photovoltaic-storage-grid-connected system to enhance the stability of the photovoltaic-storage-grid-connected system.

[0042] For details, please refer to Figure 2 , U dc is an ideal voltage source; R s is the filter resistor; L s is the filter inductor; C s is the filter capacitor; R g is the resistance of the grid; L gThe present embodiment relates to the control implementation of a photovoltaic energy storage grid-connected system (hereinafter referred to as the system). The system is mainly composed of distributed photovoltaic power sources, energy storage devices, inverters, VSG algorithms, and power grids. The control process first calculates the electrical angle θ through a virtual speed regulator, and uses a virtual excitation device to determine the amplitude E of the virtual electromotive force. m These two numbers are combined for per-unit calculation and further expanded to three-phase electrical signals. Further, the system performs dq coordinate transformation to obtain the direct-axis voltage V in per-unit form. d* and the quadrature axis voltage V q* Based on these voltage components, combined with the virtual impedance and the output current component i in the direct axis coordinate system d and i q , generating a PWM waveform signal. The PWM signal is fed into the six insulated gate bipolar transistors in the inverter circuit, thus achieving precise control of the VSG grid-connected system.

[0043] VSG active power-frequency control loop. The formula is as follows:

[0044]

[0045] Where J is the moment of inertia; ω is the system angular frequency; ω0 is the reference angular frequency; P m is the input power; P e is the electromagnetic power; D is the damping coefficient; P ref is the active reference value; K p is the active power droop coefficient; δ is the power angle.

[0046] VSG reactive power-voltage control is as follows:

[0047]

[0048] Where: Q e is the reactive power output value; Q ref is the reactive power reference value; K q is the reactive power droop coefficient; V is the output voltage, V n is the reference voltage.

[0049] The inertia adaptive adjustment link dynamically adjusts the equivalent inertia J of the grid-connected system according to the rate and amount of change of the system angular frequency. The system's VSG active power-frequency control loop uses the adaptive equivalent inertia to control the photovoltaic storage grid-connected system, that is, the adaptive equivalent inertia J is introduced into the VSG active power-frequency control loop to enhance the stability of the photovoltaic storage grid-connected system.

[0050] The method in this embodiment uses the angular frequency change rate and the angular frequency change amount to dynamically adjust the steady-state value of the moment of inertia of the photovoltaic storage grid-connected system. It can dynamically and adaptively adjust the inertia according to the actual operating state of the photovoltaic storage grid-connected system, avoiding the sudden change of the moment of inertia caused by the sharp change of angular velocity, and improving the stability and response performance of the photovoltaic storage grid-connected system. At the same time, the self-anti-disturbance control enhances the anti-interference and robustness of the photovoltaic storage grid-connected system, so that the photovoltaic storage grid-connected system can quickly recover to a steady state when facing various disturbances, reduce overshoot and oscillation, and improve the stability and reliability of the photovoltaic storage grid-connected system.

[0051] In a specific embodiment, the method of dynamically adjusting the steady-state value of the moment of inertia of the photovoltaic storage grid-connected system according to the angular frequency change rate and the angular frequency change amount of the photovoltaic storage grid-connected system to obtain an adaptive equivalent inertia includes: obtaining a preset rotational inertia threshold of the photovoltaic storage grid-connected system; when the angular frequency change rate is less than or equal to the preset rotational inertia threshold, the adaptive equivalent inertia is the steady-state value of the moment of inertia; when the angular frequency change rate is greater than the preset rotational inertia threshold, the steady-state value of the moment of inertia is adjusted according to the hyperbolic tangent function, the first-order inertia link of the photovoltaic storage grid-connected system, the angular frequency change rate and the angular frequency change amount to obtain the adaptive equivalent inertia. By adjusting the steady-state value of the moment of inertia, the dynamic response characteristics of the system can be optimized and the stability of the system can be improved. In particular, in the power system, an appropriate moment of inertia can slow down the frequency response speed and reduce the impact on the system. The adjustment of the moment of inertia can also optimize the performance of the system. For example, in the photovoltaic storage grid-connected system, by adjusting the steady-state value of the moment of inertia, the response speed and stability of the system can be balanced and the overall performance of the system can be improved.

[0052] In a specific embodiment, the adaptive equivalent inertia is obtained using the following formula:

[0053]

[0054] Wherein, J is the adaptive equivalent inertia, J0 is the steady-state value of the moment of inertia, s(x) is the hyperbolic tangent function, is the first-order inertia link of the photovoltaic energy storage grid-connected system, ω is the angular frequency of the photovoltaic energy storage grid-connected system, is the angular frequency change rate, Δω is the angular frequency change amount, G is the preset rotational inertia threshold, x is the angular frequency change rate, and k, k1 and k2 are constants.

[0055] Depend on Figure 3As shown in the figure, the range of the tanh function (i.e., the hyperbolic tangent function s(x)) is limited to [-1, 1], ensuring that the parameter changes are bounded. After the introduction of the tanh function, the range of J changes within J0±k and the derivative of tanh is continuous and smooth in the real number domain, avoiding the spike phenomenon when adjusting J. The characteristics of this function allow high gain to be provided for rapid correction when the system frequency deviation is small, that is, when the system state is close to steady state but there is a slight deviation, and when the deviation is large, the output is saturated and low gain is provided to avoid excessive response and oscillation. Preventing the system from responding too violently avoids system overshoot and oscillation.

[0056] In a specific embodiment, the method further includes: obtaining the compensation torque of the photovoltaic storage grid-connected system according to the angular frequency of the photovoltaic storage grid-connected system and a preset reference angular frequency; superimposing the compensation torque on the torque command of the active-frequency control loop. By introducing the compensation torque, the system can respond to changes in angular frequency more quickly, thereby achieving effective suppression of frequency fluctuations. This helps to maintain the stable operation of the photovoltaic storage grid-connected system and prevent system instability caused by excessive frequency fluctuations. The superposition of the compensation torque makes the torque command of the active-frequency control loop more flexible and can be dynamically adjusted according to the actual situation of the system. This dynamic adjustment capability helps the system better adapt to various operating conditions and improve overall stability.

[0057] In a specific embodiment, the compensation torque of the photovoltaic energy storage grid-connected system is obtained according to the angular frequency of the photovoltaic energy storage grid-connected system and a preset reference angular frequency, including: using a first-order differential tracker to filter and derive the reference angular frequency to obtain a first tracking signal of the reference angular frequency; performing a second-order nonlinear extended state observation on the angular frequency to obtain a second tracking signal and a disturbance observation value of the angular frequency; performing nonlinear state error feedback based on the first tracking signal, the second tracking signal and the disturbance observation value to obtain the compensation torque.

[0058] Specifically, the compensation torque is obtained by using a first-order tracking differentiator, a second-order nonlinear extended state observer, and a nonlinear state error feedback. Figure 4 As shown in FIG. 1 , an active disturbance rejection control (ADRC) is added to the VSG active-frequency control loop. ADRC takes ω0 and ω as inputs to ensure that the output signal accurately follows the ADRC instruction.

[0059] The first-order tracking differentiator (TD) is mainly responsible for accurate filtering of the input signal. By taking the angular frequency ω0 of the system as the input signal, TD can effectively eliminate noise and high-frequency disturbances, and accurately estimate the derivative v1 of the signal as the output.

[0060] In a specific embodiment, the first tracking signal is obtained using the following formula:

[0061]

[0062] Wherein, e0 is the error signal of the first-order differential tracker, ω0 is the reference angular frequency, v1 is the first tracking signal, r0 is the velocity factor, α0 is the tracking factor of the first-order differential tracker, γ0 is the filter factor of the first-order differential tracker, and f al is a continuous power function with linear segments.

[0063] In the second-order nonlinear extended state observer (NLESO), z1 represents the tracking signal of the system angular frequency ω; z2 is the disturbance observation value, which covers the disturbance inside the system and the estimation of external uncertain factors. These two signals together constitute the output of NLESO.

[0064] Nonlinear State Error Feedback (NLSEF): Its input includes v1 output by the first-order differential tracker TD, and z1 and z2 outputs of NLESO. These input signals act together on NLSEF to realize nonlinear processing and feedback control of system errors, thereby improving the dynamic response performance and anti-interference ability of the system.

[0065] In a specific embodiment, the compensation torque is obtained by using the following formula:

[0066]

[0067]

[0068] Wherein, e and e1 are error signals in the second-order nonlinear extended state observation, e2 is the tracking signal of the nonlinear state error feedback, z1 is the second tracking signal, z2 is the disturbance observation value, is the time derivative of z1, is the time derivative of z2, ω is the angular frequency, β1 and β2 are the error correction gains of the second-order nonlinear extended state observation, and f al is a continuous power function with linear segments, α1 is the tracking factor of the second-order nonlinear extended state observation, α2 is the tracking factor of the nonlinear state error feedback, γ1 is the filter factor of the second-order nonlinear extended state observation, γ2 is the filter factor of the nonlinear state error feedback, b0 is the compensation factor, u(t) is the compensation torque, v1 is the first tracking signal, u0(t) is the nonlinear error feedback control quantity, and k is the regulator gain.

[0069] In a specific embodiment, fal is a continuous power function with a linear segment near the origin, which can avoid high-frequency vibration. Its expression is:

[0070]

[0071] Among them, sgn is the sign function; α is the parameter of the fal function; γ is the parameter threshold of the fal function.

[0072] In order to verify the effectiveness of the control method in dealing with active power fluctuations, a simulation model of the photovoltaic energy storage grid-connected system was built and simulation analysis was performed. The system parameters are described in Table 1:

[0073]

[0074] Table 1: Simulation parameters

[0075] Example 1: Active Disturbance

[0076] The system is set to an active power of 150kW at t=0s, and the active power suddenly increases to 180kW at t=1s, and then recovers to 150kW at 2s. The reactive power remains at 0kvar, and the total simulation time is 3.5s. Compare the effects of traditional VSG and improved adaptive VSG. Figure 5 The VSG system with the addition of adaptive algorithm and anti-disturbance controller will not overshoot the system when the active power suddenly increases, and the control strategy is smoother, the oscillation amplitude is smaller than the traditional VSG, the time to enter the steady state is shorter, and the system response is more stable; reference Figure 6 When the system experiences the first angular frequency change, the improved adaptive VSG achieves a maximum frequency offset of 317.6 rad / s, compared with the maximum offset of 319.8 rad / s of the traditional VSG, indicating that the introduction of adaptive control algorithm and ADRC in VSG can effectively suppress angular frequency fluctuations; reference Figure 7 , the introduction of tanh function to dynamically adjust the moment of inertia can achieve smooth adjustment of the moment of inertia. This strategy effectively avoids the sudden change of the moment of inertia caused by the sharp change of angular velocity, thereby significantly reducing the possible spike phenomenon in the control system and improving the stability and response performance of the system.

[0077] Example 2: Three-phase short circuit fault

[0078] A three-phase short circuit fault simulation is used to verify transient stability. A three-phase short circuit occurs in the system at the beginning of the simulation. The fault lasts for 0.4s. The short circuit fault is removed after 0.4s. The simulation time is 3.5s. Figure 8At the moment of fault removal, the active power of the traditional VSG drops rapidly to a negative value, followed by oscillation. However, the active power of the adaptive VSG increases suddenly after the fault is removed, avoiding the situation where the active power drops to a negative value, and the oscillation amplitude is small; refer to Fig. 9 After the three-phase short-circuit fault is removed, the frequency of the traditional VSG oscillates, reaching a maximum of 53.4Hz and a minimum of 49Hz. However, after the fault is removed, the frequency oscillation of the adaptive VSG is relatively gentle, ranging from 49.6Hz to 50Hz; Fig.10 After the fault is removed, the reduction of short-circuit current of the adaptive VSG is also better than that of the traditional VSG.

[0079] In the specific embodiments, see Fig.11 , is a structural schematic diagram of a photovoltaic-storage grid-connected system stability enhancement system in the second embodiment of the present application, the system comprising: an equivalent inertia acquisition module 201 and an adaptive control module 202; the equivalent inertia acquisition module 201 is used to dynamically adjust the steady-state value of the rotational inertia of the photovoltaic-storage grid-connected system according to the angular frequency change rate and angular frequency change amount of the photovoltaic-storage grid-connected system to obtain an adaptive equivalent inertia; the adaptive control module 202 is used for the active-frequency control loop of the photovoltaic-storage grid-connected system to control the photovoltaic-storage grid-connected system using the adaptive equivalent inertia to enhance the stability of the photovoltaic-storage grid-connected system.

[0080] The system in this embodiment uses the angular frequency change rate and the angular frequency change amount to dynamically adjust the steady-state value of the moment of inertia of the photovoltaic storage grid-connected system. It can dynamically and adaptively adjust the inertia according to the actual operating state of the photovoltaic storage grid-connected system, avoiding the sudden change of the moment of inertia caused by the sharp change of angular velocity, and improving the stability and response performance of the photovoltaic storage grid-connected system. At the same time, the self-anti-disturbance control enhances the anti-interference and robustness of the photovoltaic storage grid-connected system, so that the photovoltaic storage grid-connected system can quickly recover to a steady state when facing various disturbances, reduce overshoot and oscillation, and improve the stability and reliability of the photovoltaic storage grid-connected system.

[0081] In a specific embodiment, the third embodiment of the present application provides a device for enhancing the stability of a photovoltaic storage grid-connected system, including a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the method described in any one of the first embodiments of the present application. The device in this embodiment dynamically adjusts the steady-state value of the moment of inertia of the photovoltaic storage grid-connected system by using the angular frequency change rate and the angular frequency change amount, and can dynamically and adaptively adjust the inertia according to the actual operating state of the photovoltaic storage grid-connected system, avoiding the sudden change of the moment of inertia caused by the sharp change of angular velocity, and improving the stability and response performance of the photovoltaic storage grid-connected system. At the same time, the self-anti-disturbance control enhances the anti-interference and robustness of the photovoltaic storage grid-connected system, so that the photovoltaic storage grid-connected system can quickly recover to a steady state when facing various disturbances, reduce overshoot and oscillation, and improve the stability and reliability of the photovoltaic storage grid-connected system.

[0082] In a specific embodiment, the fourth embodiment of the present application provides a computer-readable storage medium storing a computer program, and when the computer program is executed by a processor, the processor executes the steps of the method described in any one of the first embodiments of the present application. The storage medium in this embodiment dynamically adjusts the steady-state value of the moment of inertia of the photovoltaic storage grid-connected system by using the angular frequency change rate and the angular frequency change amount, and can dynamically and adaptively adjust the inertia according to the actual operating state of the photovoltaic storage grid-connected system, avoiding the sudden change of the moment of inertia caused by the sharp change of angular velocity, and improving the stability and response performance of the photovoltaic storage grid-connected system. At the same time, the self-anti-disturbance control enhances the anti-interference and robustness of the photovoltaic storage grid-connected system, so that the photovoltaic storage grid-connected system can quickly recover to a steady state when facing various disturbances, reduce overshoot and oscillation, and improve the stability and reliability of the photovoltaic storage grid-connected system.

[0083] Fig.12 The internal structure of a computer device in one embodiment is shown. The computer device can be a terminal or a server. Fig.12 The computer device includes a processor, a memory, etc. connected via a system bus. The memory includes a non-volatile storage medium and an internal memory. The non-volatile storage medium of the computer device stores an operating system and may also store a computer program. When the computer program is executed by the processor, the processor can implement the method in this embodiment. The internal memory may also store a computer program. When the computer program is executed by the processor, the processor can implement the method in this embodiment. Those skilled in the art can understand that Fig.12 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0084] The above embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

[0085] The above description is only a preferred embodiment of the present invention and does not limit the present invention in other forms. Any technician familiar with the profession may use the technical content disclosed above to change or modify it into an equivalent embodiment with equivalent changes and apply it to other fields. However, any simple modification, equivalent change and modification made to the above embodiment based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for enhancing the stability of a photovoltaic energy storage grid-connected system, characterized in that: The method comprises: Dynamically adjusting the steady-state value of the moment of inertia of the photovoltaic-storage-grid-connected system according to the angular frequency change rate and angular frequency change amount of the photovoltaic-storage-grid-connected system to obtain an adaptive equivalent inertia; The active power-frequency control loop of the photovoltaic-storage-grid-connected system uses the adaptive equivalent inertia to control the photovoltaic-storage-grid-connected system to enhance the stability of the photovoltaic-storage-grid-connected system.

2. The method for enhancing the stability of a photovoltaic energy storage grid-connected system according to claim 1, characterized in that: The step of dynamically adjusting the steady-state value of the moment of inertia of the photovoltaic-storage-grid-connected system according to the angular frequency change rate and angular frequency change amount of the photovoltaic-storage-grid-connected system to obtain an adaptive equivalent inertia includes: Obtaining a preset rotational inertia threshold of the photovoltaic energy storage grid-connected system; When the angular frequency change rate is less than or equal to the preset rotational inertia threshold, the adaptive equivalent inertia is the steady-state value of the rotational inertia; When the angular frequency change rate is greater than the preset rotational inertia threshold, the steady-state value of the moment of inertia is adjusted according to the hyperbolic tangent function, the first-order inertia link of the photovoltaic energy storage grid-connected system, the angular frequency change rate and the angular frequency change amount to obtain the adaptive equivalent inertia.

3. The method for enhancing the stability of a photovoltaic energy storage grid-connected system according to claim 2, characterized in that: The adaptive equivalent inertia is obtained by the following formula: Wherein, J is the adaptive equivalent inertia, J0 is the steady-state value of the moment of inertia, s(x) is the hyperbolic tangent function, is the first-order inertia link of the photovoltaic energy storage grid-connected system, ω is the angular frequency of the photovoltaic energy storage grid-connected system, is the angular frequency change rate, Δω is the angular frequency change amount, G is the preset rotational inertia threshold, x is the angular frequency change rate, and k, k1 and k2 are constants.

4. The method for enhancing the stability of a photovoltaic energy storage grid-connected system according to claim 1, characterized in that: The method further comprises: Obtaining the compensation torque of the photovoltaic and energy storage grid-connected system according to the angular frequency of the photovoltaic and energy storage grid-connected system and a preset reference angular frequency; The compensation torque is added to the torque command of the active power-frequency control loop.

5. The method for enhancing the stability of a photovoltaic energy storage grid-connected system according to claim 4, characterized in that: The step of obtaining the compensation torque of the photovoltaic-storage-grid-connected system according to the angular frequency of the photovoltaic-storage-grid-connected system and a preset reference angular frequency includes: Using a first-order differential tracker to filter and derive the reference angular frequency, to obtain a first tracking signal of the reference angular frequency; Performing a second-order nonlinear extended state observation on the angular frequency to obtain a second tracking signal and a disturbance observation value of the angular frequency; Nonlinear state error feedback is performed according to the first tracking signal, the second tracking signal and the disturbance observation value to obtain the compensation torque.

6. The method for enhancing the stability of a photovoltaic energy storage grid-connected system according to claim 5, characterized in that: The compensation torque is obtained by the following formula: Wherein, e and e1 are error signals in the second-order nonlinear extended state observation, e2 is the tracking signal of the nonlinear state error feedback, z1 is the second tracking signal, z2 is the disturbance observation value, is the time derivative of z1, is the time derivative of z2, ω is the angular frequency, β1 and β2 are the error correction gains of the second-order nonlinear extended state observation, and f al is a continuous power function with linear segments, α1 is the tracking factor of the second-order nonlinear extended state observation, α2 is the tracking factor of the nonlinear state error feedback, γ1 is the filter factor of the second-order nonlinear extended state observation, γ2 is the filter factor of the nonlinear state error feedback, b0 is the compensation factor, u(t) is the compensation torque, v1 is the first tracking signal, u0(t) is the nonlinear error feedback control quantity, and k is the regulator gain.

7. The method for enhancing the stability of a photovoltaic energy storage grid-connected system according to claim 5, characterized in that: The first tracking signal is obtained using the following formula: Wherein, e0 is the error signal of the first-order differential tracker, ω0 is the reference angular frequency, v1 is the first tracking signal, r0 is the velocity factor, α0 is the tracking factor of the first-order differential tracker, γ0 is the filter factor of the first-order differential tracker, and f al is a continuous power function with linear segments.

8. A photovoltaic energy storage grid-connected system stability enhancement system, characterized in that: The system comprises: an equivalent inertia acquisition module and an adaptive control module; The equivalent inertia acquisition module is used to dynamically adjust the steady-state value of the rotational inertia of the photovoltaic storage grid-connected system according to the angular frequency change rate and angular frequency change amount of the photovoltaic storage grid-connected system to obtain an adaptive equivalent inertia; The adaptive control module is used in the active power-frequency control loop of the photovoltaic-storage-grid-connected system to control the photovoltaic-storage-grid-connected system using the adaptive equivalent inertia to enhance the stability of the photovoltaic-storage-grid-connected system.

9. A device for enhancing the stability of a photovoltaic energy storage grid-connected system, comprising a memory and a processor, characterized in that: The memory stores a computer program, and when the computer program is executed by the processor, the processor is caused to perform the steps of the method according to any one of claims 1 to 7.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the processor is caused to perform the steps of the method according to any one of claims 1 to 7.

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