A VSG coordination control method and device based on improved adaptive and feedforward compensation

Abstract

The application discloses a kind of VSG coordination control method and device based on improved adaptive and feedforward compensation, comprising: the model of VSG light storage grid-connected system is established, and the power angle characteristic and frequency oscillation curve are analyzed;Introduce arctangent function optimization traditional adaptive control strategy, smooth adjustment moment of inertia and damping coefficient;Join feedforward compensation control strategy, establish active compensation expression and rotor motion equation and coordinate setting compensation coefficient and filter time constant, reconstruct the small signal model change zero-point-pole pair configuration under disturbance of active power reference value;Based on the adaptive control strategy adjusted after optimization virtual moment of inertia and damping coefficient, based on feedforward compensation control strategy, power reference value is corrected in advance by predicting frequency fluctuation;The application effectively suppresses power overshoot, frequency variation deviation, realizes the smooth adjustment of moment of inertia and VSG dynamic performance optimization, enhances system response speed and stability.

Description

Technical Field

[0001] This invention relates to the field of microgrid coordinated control technology, and more specifically to a VSG coordinated control method and device based on improved adaptive and feedforward compensation. Background Technology

[0002] With increasingly severe energy and environmental problems, the penetration rate of renewable energy is constantly increasing, and new power systems centered on "high efficiency and high voltage" are rapidly developing. The role of photovoltaic and energy storage systems in new energy power generation and power systems is also becoming increasingly significant. However, most power electronic devices lack inertia and damping characteristics, resulting in poor ability to suppress system fluctuations and thus reducing energy utilization efficiency. To address these issues, researchers have proposed the emerging technology of Virtual Synchronous Generator (VSG) to control inverters, providing the necessary inertia and damping for microgrid systems. This better solves problems related to frequency and voltage regulation and enhances system stability.

[0003] The flexibility and adjustability of VSG control strategies enable photovoltaic-storage microgrid systems to better adapt to the needs of the power grid and achieve efficient energy conversion and management. However, in traditional VSG control, the moment of inertia and damping coefficient are constant, which has limitations.

[0004] In existing technologies, the "Improved Virtual Synchronous Control Strategy Based on Multi-Parameter Cooperative Adaptation" published in the 6th issue of "Power System Technology" in 2023 comprehensively considers the variation laws of rotational inertia, damping coefficient, and droop coefficient, and realizes adaptive cooperative control of the three. The "Adaptive Virtual Synchronous Generator Control Strategy Based on Fuzzy Control" published in the 1st issue of "Guangdong Electric Power" in 2020 proposes a VSG control scheme based on fuzzy algorithms, using a new fuzzy controller to tune parameters, but it requires relying on empirically designed rule bases. The "Adaptive Control of VSG Virtual Inertia and Dynamic Damping Compensation Based on RBF" published in the 2nd issue of "Power System Protection and Control" in 2024 introduces a neural network to use the damping coefficient and damping compensation amount together as the equivalent damping coefficient of the system, thereby achieving decoupling between parameters and enabling the system to adapt to frequency. The system adaptively adjusts to changes in voltage; the article "VSG Voltage Control Strategy Based on Adaptive Inertia Coefficient and Droop Coefficient" in the first issue of "Mathematical Problems in Engineering" in 2021 adjusts the inertia coefficient and droop coefficient in real time according to the voltage deviation, which can reduce frequency fluctuations during load switching and ensure stable system operation; the article "Optimization Strategy of Active Power Response of Energy Storage VSG Based on Frequency Feedforward Compensation" in the second issue of "Acta Energiae Solaris Sinica" in 2024 enhances system damping and effectively suppresses frequency overshoot by introducing a frequency compensation transfer function into the rotor motion equation; the article "VSG Active Power Control Based on Angular Frequency Deviation Compensation" in the ninth issue of "Power System Technology" in 2019 adjusts the active power output of VSG by compensating for angular frequency deviation, thereby improving the speed at which VSG follows changes in active power commands.

[0005] While the above methods can alleviate the overshoot problem, they fail to adequately balance the requirements of smooth parameter adjustment and rapid system response. When the photovoltaic energy storage system is subjected to disturbances, the VSG exhibits problems such as power overshoot and frequency oscillation.

[0006] Therefore, how to provide a VSG coordinated control strategy to suppress power overshoot and frequency variation deviation, achieve smooth adjustment of rotational inertia and optimization of VSG dynamic performance, so as to enhance system response speed and stability, is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0007] In view of this, the present invention provides a VSG coordinated control method and apparatus based on improved adaptive and feedforward compensation to solve the technical problems mentioned in the background art.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A VSG coordinated control method based on improved adaptive and feedforward compensation includes the following steps:

[0010] S1. Based on the model foundation of photovoltaic-storage microgrid and the dynamic response characteristics under different operating conditions, a model of VSG photovoltaic-storage grid-connected system including hybrid energy storage unit and inverter is established, and the power angle characteristics and frequency oscillation curve are analyzed.

[0011] S2. Divide the power angle and angular frequency of the VSG into multiple intervals, analyze the characteristics of angular velocity change caused by the change of input power in each interval, determine the adjustment direction of the moment of inertia and damping coefficient, and use the characteristic of continuous differentiability of the arctangent function to design an improved adaptive control equation to achieve smooth adjustment of both.

[0012] S3. Add a feedforward compensation circuit to the VSG controller to superimpose the collected grid frequency or power disturbance signal onto the active power reference value to achieve advance adjustment and work in coordination with the improved adaptive control; establish the active power compensation expression and rotor motion equation of AFC-VSG, coordinate the setting of compensation coefficient and filter time constant, and optimize the zero-pole pair configuration.

[0013] S4. Real-time data acquisition: Based on the feedforward compensation control strategy, the power reference value is corrected in advance by predicting frequency fluctuations, and the virtual rotational inertia and damping coefficient of the VSG are adjusted based on the optimized adaptive control strategy to achieve dynamic matching between the two under different operating conditions and suppress deviations caused by frequency and power disturbances.

[0014] Preferably, step S1 specifically includes:

[0015] Establish the rotor motion equivalent equation, active power loop control equation, and reactive power loop control equation for the synchronous generator;

[0016] Combining the traditional small-signal model analysis method of synchronous generators, the closed-loop transfer function of the VSG active power loop is derived;

[0017] Determine the natural oscillation angular frequency and damping ratio;

[0018] Based on the underdamped state of the system, the maximum overshoot and settling time of the synchronous generator are analyzed.

[0019] Preferably, in step S1, when the microgrid is operating normally, the rotor's equation of motion is equivalent to:

[0020]

[0021] Where J is the virtual moment of inertia of the VSG, D is the damping coefficient, and T... m T e T d These are mechanical torque, electromagnetic torque, and damping torque, respectively, P e P mThese represent electromagnetic power and mechanical power, respectively; ω and ω0 represent the actual angular velocity and rated angular velocity of the VSG, respectively; and δ represents the power angle of the synchronous generator.

[0022] The active power loop control equation of the VSG is:

[0023] P m =P ref -K f (ω-ω0)

[0024] Among them, P ref K is a reference value for active power. f This is the primary frequency modulation coefficient;

[0025] The reactive power loop control equation for the VSG is:

[0026] E = E0 + K n (Q ref -Q)+K u (U ref -U)

[0027] Where E0 is the no-load electromotive force of VSG, and Q ref U is the reference value for reactive power, Q is the actual value of reactive power, and U is the reference value for reactive power. ref U and K represent the set value and measured value of the VSG output voltage, respectively. n and K u These are the reactive power droop coefficient and the voltage compensation coefficient, respectively.

[0028] The closed-loop transfer function of the VSG active power loop is:

[0029]

[0030] Where X is the line equivalent reactance;

[0031] Natural oscillation frequency ω n The damping ratio ξ is:

[0032]

[0033] The maximum overshoot and settling time are as follows:

[0034]

[0035] Preferably, the adaptive control strategy optimized by the arctangent function in step S2 is as follows:

[0036]

[0037] Where J0 and D0 are the moment of inertia and damping coefficient of the system in the initial steady state, respectively, and K... j K is the adjustment coefficient for the moment of inertia.d T is the adjustment coefficient for the damping coefficient. j T is the threshold value for the rate of change of angular velocity. d K is the threshold for frequency variation, i.e., deviation. Δ ω is the frequency compensation coefficient.

[0038] Preferably, in step S3, after adding the feedforward compensation control strategy, the active power compensation expression and rotor motion equation of the AFC-VSG are:

[0039]

[0040] Among them, K AFC T is the compensation coefficient for AFC-VSG. f This is the filtering time constant.

[0041] Preferably, the active power reference value P ref The small-signal model under disturbance is as follows:

[0042]

[0043] in,

[0044]

[0045] Preferably, in order to improve the working efficiency of the VSG, the moment of inertia J satisfies the following condition:

[0046]

[0047] Adjustment coefficient K of rotational inertia j The adjustment coefficient K of the damping coefficient d Conditions met:

[0048]

[0049] A computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the aforementioned VSG coordinated control method based on improved adaptive and feedforward compensation.

[0050] A processing terminal includes a memory and a processor. The memory stores a computer program that can run on the processor. When the processor executes the computer program, it implements the aforementioned VSG coordinated control method based on improved adaptive and feedforward compensation.

[0051] As can be seen from the above technical solutions, compared with the prior art, the present invention discloses a VSG coordinated control method and device based on improved adaptive and feedforward compensation. A model of the photovoltaic storage system and VSG is built. By introducing the arctangent function to optimize the traditional adaptive control method, the continuous differentiability of the function is used to achieve smooth adjustment of the moment of inertia. A feedforward compensation link is added to the VSG controller to coordinate with the adaptive control. The collected signal is superimposed on the active power reference value for advance adjustment. The transfer function is reconstructed to change the zero-pole pair configuration, optimize the dynamic performance of the VSG, and enhance the system response speed and stability. Attached Figure Description

[0052] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0053] Figure 1 A schematic diagram of a VSG coordinated control method based on improved adaptive and feedforward compensation provided by the present invention;

[0054] Figure 2 A schematic diagram of the overall structure of the VSG photovoltaic-storage grid-connected system provided by the present invention;

[0055] Figure 3 A schematic diagram illustrating the active and reactive power control principles of the VSG provided by this invention;

[0056] Figure 4 This is a schematic diagram of the traditional VSG small-signal model provided by the present invention;

[0057] Figure 5 A schematic diagram of the power angle curve and frequency oscillation curve provided by the present invention;

[0058] Figure 6 A schematic diagram illustrating the selection principles for virtual inertia and damping coefficient provided by this invention;

[0059] Figure 7 A schematic diagram of the AFC-VSG grid-connected active power equivalent control principle provided by the present invention;

[0060] Figure 8 K provided for the present invention AFC Schematic diagram of the change in root locus as the number increases;

[0061] Figure 9 This is a schematic diagram of the root locus change when J and D change, as provided by the present invention.

[0062] Figure 10 A schematic diagram of active power variation curves under four different control strategies provided by this invention;

[0063] Figure 11 Schematic diagram of frequency oscillation variation curves under four different control strategies provided by the present invention;

[0064] Figure 12 A comparative diagram of the changes in rotational inertia provided by the present invention;

[0065] Figure 13 This is a schematic diagram of the damping coefficient variation provided by the present invention;

[0066] Figure 14 The conventional VSG output current waveform diagram provided by this invention;

[0067] Figure 15 The output current waveform of VSG based on improved adaptive and feedforward compensation is provided for this invention. Detailed Implementation

[0068] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0069] This invention discloses a VSG coordinated control method based on improved adaptive and feedforward compensation, such as... Figure 1 This includes the following steps:

[0070] S1. Based on the model foundation of photovoltaic-storage microgrid and the dynamic response characteristics under different operating conditions, a model of VSG photovoltaic-storage grid-connected system including hybrid energy storage unit and inverter is established, and the power angle characteristics and frequency oscillation curve are analyzed.

[0071] S2. Divide the power angle and angular frequency of the VSG into multiple intervals, analyze the characteristics of angular velocity change caused by the change of input power in each interval, determine the adjustment direction of the moment of inertia and damping coefficient, and use the characteristic of continuous differentiability of the arctangent function to design an improved adaptive control equation to achieve smooth adjustment of both.

[0072] S3. Add a feedforward compensation circuit to the VSG controller to superimpose the collected grid frequency or power disturbance signal onto the active power reference value to achieve advance adjustment and work in coordination with the improved adaptive control; establish the active power compensation expression and rotor motion equation of AFC-VSG, coordinate the setting of compensation coefficient and filter time constant, and optimize the zero-pole pair configuration.

[0073] S4. Real-time data acquisition: Based on the feedforward compensation control strategy, the power reference value is corrected in advance by predicting frequency fluctuations, and the virtual rotational inertia and damping coefficient of the VSG are adjusted based on the optimized adaptive control strategy to achieve dynamic matching between the two under different operating conditions and suppress deviations caused by frequency and power disturbances.

[0074] In this embodiment, a VSG photovoltaic-storage grid-connected system model including a hybrid energy storage unit and an inverter is established as follows: Figure 2 As shown, the collected voltage and current are input into the voltage and current dual closed-loop control system. After sinusoidal pulse width modulation, the output signal controls the switching on and off of the inverter. The photovoltaic array adopts a maximum power point tracking strategy, enabling it to efficiently output the maximum possible power under various lighting conditions. Since a single battery cannot simultaneously possess the advantages of multiple energy storage devices, in order to improve output performance and extend cycle life, a photovoltaic-energy storage system combining batteries and supercapacitors is adopted. An active parallel topology is selected and connected to the same DC bus. This method helps to smooth out bus voltage fluctuations and optimize energy distribution and utilization.

[0075] Figure 2 In the middle, C dc For voltage regulation capacitors, L and C represent filter inductors and filter capacitors, respectively, and Z... line Let Z be the line impedance, Z be the load, and P and Q be the active and reactive power outputs of the VSG, respectively. ref Q ref These are the reference values ​​for active power and reactive power, respectively. Lab c is the inductor current, u c This is the capacitor voltage.

[0076] To further implement the above technical solution, step S1 specifically includes:

[0077] Establish the rotor motion equivalent equation, active power loop control equation, and reactive power loop control equation for the synchronous generator;

[0078] Combining the traditional small-signal model analysis method of synchronous generators, the closed-loop transfer function of the VSG active power loop is derived;

[0079] Determine the natural oscillation angular frequency and damping ratio;

[0080] Based on the underdamped state of the system, the maximum overshoot and settling time of the synchronous generator are analyzed.

[0081] To further implement the above technical solution, in step S1, when the microgrid is operating normally, the rotor's motion equation is equivalent to:

[0082]

[0083] Where J is the virtual moment of inertia of the VSG, D is the damping coefficient, and T... m T e T d These are mechanical torque, electromagnetic torque, and damping torque, respectively, P e P m These represent electromagnetic power and mechanical power, respectively; ω and ω0 represent the actual angular velocity and rated angular velocity of the VSG, respectively; and δ represents the power angle of the synchronous generator.

[0084] like Figure 3 The active power loop control equation of the VSG is:

[0085] P m =P ref -K f (ω-ω0)

[0086] Among them, P ref K is a reference value for active power. f This is the primary frequency modulation coefficient;

[0087] The reactive power loop control equation for the VSG is:

[0088] E = E0 + K n (Q ref -Q)+K u (U ref -U)

[0089] Where E0 is the no-load electromotive force of VSG, and Q ref U is the reference value for reactive power, Q is the actual value of reactive power, and U is the reference value for reactive power. ref U and K represent the set value and measured value of the VSG output voltage, respectively. n and K u These are the reactive power droop coefficient and the voltage compensation coefficient, respectively.

[0090] like Figure 4 Combining the traditional small-signal model analysis method for synchronous generators, the closed-loop transfer function of the VSG active power loop is derived as follows:

[0091]

[0092] Where X is the line equivalent reactance;

[0093] Natural oscillation frequency ω n The damping ratio ξ is:

[0094]

[0095] The maximum overshoot and settling time are as follows:

[0096]

[0097] In this embodiment, after receiving the active and reactive power commands from the VSG, the dynamic response of the system is mainly affected by the moment of inertia J, the damping coefficient D, and the frequency modulation coefficient K. f Three key parameters have an impact, and in practice, K f Generally kept constant, the dynamic performance of the system is mainly adjusted by changes in J and D. When J is kept constant, increasing D will increase the system damping ratio ξ, thereby reducing the overshoot σ% and shortening the settling time t. s When D remains constant, increasing J will lead to a decrease in ξ, which in turn leads to an increase in σ% and a longer settling time t. s The power angle and frequency oscillation curves of the VSG are as follows: Figure 5 As shown, the selection criteria for the two parameters under different conditions are derived, and the selection principles for virtual inertia and damping coefficient are as follows: Figure 6 As shown.

[0098] To further implement the above technical solution, step S2 introduces an adaptive control strategy optimized by the arctangent function, specifically as follows:

[0099]

[0100] Where J0 and D0 are the moment of inertia and damping coefficient of the system in the initial steady state, respectively, and K... j K is the adjustment coefficient for the moment of inertia. d T is the adjustment coefficient for the damping coefficient. j T is the threshold value for the rate of change of angular velocity. d K is the threshold for frequency variation, i.e., deviation. Δ ω is the frequency compensation coefficient.

[0101] In practical power systems, fixed moments of inertia and damping coefficients are usually set, which limits the adaptability and flexibility of VSG in response to different disturbances. In this embodiment, by introducing adaptive control technology, the J and D of VSG can be adjusted according to real-time conditions, enabling VSG to more accurately match the needs of the system. In particular, when disturbances occur, it can quickly adjust its own parameters to enhance dynamic regulation capabilities.

[0102] To further implement the above technical solution, in step S3, after adding the feedforward compensation control strategy, the active power compensation expression and rotor motion equation of AFC-VSG are as follows:

[0103]

[0104] Among them, K AFC T is the compensation coefficient for AFC-VSG. f This is the filtering time constant.

[0105] Since adaptive control is generally more complex than fixed-parameter control, and to avoid overshooting or oscillations that could lead to overly conservative parameter design, K is added. Δ ω, when a feedforward compensation stage is added, the VSG can respond to grid frequency fluctuations more quickly and adjust its output power in a timely manner, therefore in Figure 4 Based on the closed-loop transfer function of the traditional VSG active power loop, the AFC-VSG control block diagram is improved, as shown below. Figure 7 As shown.

[0106] To further implement the above technical solution, the active power reference value P ref The small-signal model under disturbance is as follows:

[0107]

[0108] in,

[0109]

[0110] Because proportional and integral control elements were added to the feedforward control loop, the system gained an additional zero and a pole, and the positions of the poles also changed. Therefore, it is necessary to set T appropriately. f and K AFC The value of T should not be too small, otherwise the dynamic response characteristics of the system cannot be improved, and usually T f The value should not be too large, otherwise it will cause system delays.

[0111] With K AFC Taking the increase from 0 to 2000 as an example, the system root locus change graph is as follows: Figure 8 As shown:

[0112] Depend on Figure 8 It can be seen that since the zeros and poles are always located in the left half of the complex plane, introducing feedforward compensation will not affect the stability of the system; when K AFC As the voltage increases, the distance between zero Z1 and pole p1 becomes almost zero, forming a dipole pair. Their effects cancel each other out and are negligible. Meanwhile, zero Z2 moves horizontally to the left, indicating an improved dynamic response of the system. Poles p2 and p3 gradually approach each other from left to right but remain in the left half-plane, changing from an overdamped state to an underdamped state, thus increasing the response speed. The poles and zeros cooperate to achieve a good balance between velocity and stability, but K... AFC It cannot be increased indefinitely, otherwise it may lead to overshoot and affect the dynamic performance of the system; K Δ ω and K AFC The function is similar; when one parameter is restricted from being increased or decreased, the other parameter can be set appropriately to improve the system's robustness to parameter changes and external disturbances.

[0113] The root loci of J and D when they change are as follows: Figure 9 As shown, by Figure 9 It can be seen that when D is fixed at 15, as J increases from 0 to 15, its conjugate complex roots p4 and p5 move to the left in the direction of the arrow in the figure, and the system response speed slows down. Therefore, the value of J cannot be too large. When J is constant, as D increases from 0 to 40, p6 and p7 first move away from the imaginary axis and move closer to the real axis. At this time, the system is in an underdamped state, and the overshoot decreases. As D continues to increase, p6 and p7 move in the opposite direction along the negative real axis. At this time, the system settling time becomes longer. Therefore, the value of D cannot be too large either. The values ​​of both should be considered in combination with various conditions.

[0114] To further implement the above technical solution and improve the working efficiency of VSG, the condition that the moment of inertia J must satisfy is:

[0115]

[0116] By adjusting the adjustment coefficient K of the moment of inertia and damping coefficient j and K d It can help VSG respond more accurately to changes in grid power and frequency, and the adjustment coefficient K of the moment of inertia. j The adjustment coefficient K of the damping coefficient d Conditions met:

[0117]

[0118] In another embodiment, the VSG coordinated control method based on the improved adaptive and feedforward compensation of the present invention is compared with the simulation of three existing control strategies: traditional VSG, improved adaptive strategy, and FFC-VSG.

[0119] Assuming the initial reference power of the VSG is 15kW, when the power changes, it suddenly increases to 20kW at 0.5s, and finally changes back to 15kW at 0.8s. The output power changes of the VSG under four control strategies are as follows: Figure 8 As shown:

[0120] Depend on Figure 10It can be seen that the active power overshoot of the traditional control strategy is 7.1% and the settling time is about 0.31s; the active power overshoot of the improved adaptive control strategy is 3.3% and the settling time is about 0.21s; although the active power of the FFC-VSG control method has no overshoot, the recovery time to stability is too long, about 0.24s; while the active power overshoot of the control strategy proposed in this invention is only 0.5% and the settling time is about 0.09s; when the power recovers to 15kW in 0.8s, it can also be clearly seen that the control strategy proposed in this invention can better reduce the settling time, effectively suppress the active power overshoot, and enable the system to quickly recover to a stable state.

[0121] Figure 11 The graphs show the frequency variation caused by power disturbances under four different control strategies for the VSG: Figure 9 It can be seen that when the power suddenly increases from 15kW to 20kW, the maximum output frequency deviation of the traditional control strategy is 0.2Hz, and the adjustment time is about 0.22s. The maximum output frequency deviation of the improved adaptive control strategy is 0.14Hz, and the adjustment time is about 0.18s. The maximum output frequency deviation of the FFC-VSG is 0.07Hz, and the adjustment time is about 0.2s. However, under the control strategy proposed in this invention, the maximum output frequency deviation is only 0.1Hz, and the adjustment time is about 0.098s. Therefore, the control strategy proposed in this invention has advantages in suppressing the rate of frequency change and reducing the duration of frequency oscillation, and the control effect is better.

[0122] Figure 12 and Figure 13 This invention demonstrates that, when an active power disturbance occurs, the moment of inertia and damping coefficient can be adjusted as needed, wherein the range of variation of the moment of inertia is approximately 0.1 to 0.43 kg·m. 2 The damping coefficient varies from approximately 15 to 21.5 N·m·s / rad. It can be seen that the two parameters, rotational inertia J and damping coefficient D, in the strategy proposed in this paper can change smoothly. However, the response speed and stability of the improved adaptive control are slightly worse, and spikes appear. On the other hand, it also indicates that the energy storage system can provide additional energy to supplement or absorb the excess or insufficient power caused by frequency changes.

[0123] Figure 14 and Figure 15 The graphs show a comparison of current waveforms under different control strategies: (The graphs are from...) Figure 11 It is known that when the system power suddenly increases or decreases, the current output by a traditional VSG will fluctuate drastically and be accompanied by a large overshoot. In contrast, the control strategy proposed in this invention can significantly improve the situation of rapid current changes and enable it to quickly transition to a stable state.

[0124] Simulation results in this embodiment demonstrate that the control strategy proposed in this invention has significant advantages over the other three control schemes. By dynamically adjusting the moment of inertia and damping coefficient, the VSG can not only significantly slow down the rate of frequency change, but also effectively control the frequency offset amplitude, thereby reducing frequency overshoot. After adding the feedforward compensation control loop, the output power can also be adjusted in advance, thereby accelerating the dynamic response speed of the system.

[0125] A computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements a VSG coordinated control method based on an improved adaptive and feedforward compensation.

[0126] A processing terminal includes a memory and a processor. The memory stores a computer program that can run on the processor. When the processor executes the computer program, it implements a VSG coordinated control method based on an improved adaptive and feedforward compensation.

[0127] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0128] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A VSG coordinated control method based on improved adaptive and feedforward compensation, characterized in that, Includes the following steps: S1. Based on the model foundation of photovoltaic-storage microgrid and the dynamic response characteristics under different operating conditions, a model of VSG photovoltaic-storage grid-connected system including hybrid energy storage unit and inverter is established, and the power angle characteristics and frequency oscillation curve are analyzed. S2. Divide the power angle and angular frequency of the VSG into multiple intervals, analyze the characteristics of angular velocity change caused by the change of input power in each interval, determine the adjustment direction of the moment of inertia and damping coefficient, and use the characteristic of continuous differentiability of the arctangent function to design an improved adaptive control equation to achieve smooth adjustment of both. S3. Add a feedforward compensation circuit to the VSG controller to superimpose the collected grid frequency or power disturbance signal onto the active power reference value to achieve advance adjustment and work in coordination with the improved adaptive control; establish the active power compensation expression and rotor motion equation of AFC-VSG, coordinate the setting of compensation coefficient and filter time constant, and optimize the zero-pole pair configuration. S4. Real-time data acquisition: Based on the feedforward compensation control strategy, the power reference value is corrected in advance by predicting frequency fluctuations, and the virtual rotational inertia and damping coefficient of VSG are adjusted based on the optimized adaptive control strategy to achieve dynamic matching between the two under different operating conditions and suppress deviations caused by frequency and power disturbances. Step S2 introduces the adaptive control strategy optimized by the arctangent function as follows: Where J0 and D0 are the moment of inertia and damping coefficient of the system in the initial steady state, respectively, and K... j K is the adjustment coefficient for the moment of inertia. d T is the adjustment coefficient for the damping coefficient. j T is the threshold value for the rate of change of angular velocity. d K is the threshold for frequency variation, i.e., deviation. Δω Here, ω is the frequency compensation coefficient, and ω is the actual angular velocity of the VSG. Step S3, after adding the feedforward compensation control strategy, the active power compensation expression and rotor motion equation of the AFC-VSG are: Among them, K AFC T is the compensation coefficient for AFC-VSG. f P is the filtering time constant. ref P is the reference value for active power. e This refers to electromagnetic power.

2. The VSG coordinated control method based on improved adaptive and feedforward compensation according to claim 1, characterized in that, Step S1 specifically includes: Establish the rotor motion equivalent equation, active power loop control equation, and reactive power loop control equation for the synchronous generator; Combining the traditional small-signal model analysis method of synchronous generators, the closed-loop transfer function of the VSG active power loop is derived; Determine the natural oscillation angular frequency and damping ratio; Based on the underdamped state of the system, the maximum overshoot and settling time of the synchronous generator are analyzed.

3. The VSG coordinated control method based on improved adaptive and feedforward compensation according to claim 2, characterized in that, Step S1, when the microgrid is operating normally, the equivalent equation of motion for the rotor is: in, Let denoted as the virtual moment of inertia of the VSG, D as the damping coefficient, Tm, Te, and Td as the mechanical torque, electromagnetic torque, and damping torque, respectively, Pe and Pm as the electromagnetic power and mechanical power, ω and ω0 as the actual angular velocity and rated angular velocity of the VSG, and δ as the power angle of the synchronous generator. The active power loop control equation of the VSG is: Among them, P ref K is a reference value for active power. f This is the primary frequency modulation coefficient; The reactive power loop control equation for the VSG is: Where E0 is the no-load electromotive force of VSG, and Q ref U is the reference value for reactive power, Q is the actual value of reactive power, and U is the reference value for reactive power. ref U and U are the set value and measured value of the VSG output voltage, respectively, and Kn and Ku are the reactive power droop coefficient and voltage compensation coefficient, respectively. The closed-loop transfer function of the VSG active power loop is: Where X is the line equivalent reactance; Natural oscillating angular frequency Damping ratio for: The maximum overshoot and settling time are as follows: 。 4. The VSG coordinated control method based on improved adaptive and feedforward compensation according to claim 1, characterized in that, Active power reference value P ref The small-signal model under disturbance is as follows: in, 。 5. The VSG coordinated control method based on improved adaptive and feedforward compensation according to claim 1, characterized in that, To improve the efficiency of the VSG, the moment of inertia J must satisfy the following condition: Adjustment coefficient K of rotational inertia j The adjustment coefficient K of the damping coefficient d Conditions met: 。 6. The VSG coordinated control method based on improved adaptive and feedforward compensation according to claim 1, characterized in that, The specific content of step S4 is as follows: S41. Collect the actual operating frequency of the VSG and the rated frequency of the system, and calculate the frequency deviation; S42. Collect the current output active power of VSG and the set active power reference value for reference calculation in the feedforward compensation stage; S43. By monitoring power deviation and its trend, and combining it with the prediction of frequency fluctuations, the power reference value is corrected in advance, and the feedforward compensation signal is superimposed on the reference value to achieve a rapid response to power disturbances. S44. Combine the conditional threshold to determine the current interval, and adjust the virtual moment of inertia and damping number of VSG in real time through adaptive control equations to achieve dynamic matching between the two under different operating conditions and suppress deviations caused by frequency and power disturbances.

7. A computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by a processor, the computer program implements a VSG coordinated control method based on an improved adaptive and feedforward compensation as described in any one of claims 1-6.

8. A processing terminal, comprising a memory and a processor, wherein the memory stores a computer program executable on the processor, characterized in that, When the processor executes the computer program, it implements a VSG coordinated control method based on any one of claims 1-6.

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