VSG coordination control method and device based on improved self-adaption and feed-forward compensation

Abstract

The invention discloses a VSG coordinated control method and device based on improved self-adaption and feed-forward compensation, and the method comprises the steps: building a model of a VSG optical storage grid-connected system, and analyzing a power angle characteristic and a frequency oscillation curve; introducing an arc tangent function to optimize a traditional adaptive control strategy, and smoothly adjusting rotational inertia and a damping coefficient; a feed-forward compensation control strategy is added, an active compensation expression and a rotor motion equation are established, a compensation coefficient and a filtering time constant are set in a coordinated mode, and configuration of a small-signal model change zero-pole pair of an active power reference value under disturbance is reconstructed; adjusting virtual rotational inertia and a damping coefficient based on the optimized adaptive control strategy, and correcting a power reference value in advance by predicting frequency fluctuation based on a feed-forward compensation control strategy; according to the method, power overshoot and frequency change deviation are effectively suppressed, smooth adjustment of rotational inertia and VSG dynamic performance optimization are realized, and the system response speed and stability are enhanced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of micro-grid coordinated control, and more particularly to a VSG coordinated control method and device based on an improved adaptive and feedforward compensation. BACKGROUND

[0002] With the increasingly serious energy and environmental problems, the penetration rate of renewable energy is constantly increasing, and the new power system with "double high" as the core is developing rapidly. The role of the light storage system in new energy power generation and power system is also increasingly significant. However, most power electronic devices lack inertia and damping characteristics, and the ability to suppress system fluctuations is poor, thereby reducing the efficiency of energy utilization. In view of the above problems, relevant scholars propose the emerging technology of virtual synchronous generator (VSG) to control the inverter, which provides the required inertia and damping for the micro-grid system, so as to better solve the problems of frequency and voltage regulation, and enhance the stability of the system.

[0003] The flexibility and adjustability of the VSG control strategy enable the light storage micro-grid system to better adapt to the demand of the power grid, and realize efficient energy conversion and management. However, in the traditional VSG control, the rotational inertia and damping coefficient are constant values, which has limitations.

[0004] In the prior art, in the 6th issue of 2023, the "Improved virtual synchronous control strategy of multi-parameter cooperative self-adaptation" of the Power Grid Technology comprehensively considers the change law of the moment of inertia, the damping coefficient and the droop coefficient, realizes the adaptive cooperative control of the three, in the 1st issue of 2020, the "Adaptive virtual synchronous generator control strategy based on fuzzy control" of Guangdong Electric Power proposes a VSG control scheme based on fuzzy algorithm, which uses a new fuzzy controller to set parameters, but needs to rely on experience design rule base, in the 2nd issue of 2024, the "VSG virtual inertia and dynamic damping compensation adaptive control based on RBF" of Power System Protection and Control introduces a neural network to take the damping coefficient and the damping compensation as the equivalent damping coefficient of the system, thereby realizing the decoupling between the parameters and enabling the system to adaptively adjust according to the change of frequency, in the 1st issue of 2021, the "VSG voltage control strategy based on adaptive inertia coefficient and droop coefficient" of Engineering Mathematics Problems adjusts the inertia coefficient and the droop coefficient in real time according to the voltage deviation, which can reduce the frequency fluctuation when the load is switched, while ensuring the stable operation of the system, in the 2nd issue of 2024, the "Energy storage VSG grid-connected active response optimization strategy based on frequency feedforward compensation" of the Journal of Solar Energy introduces a frequency compensation transfer function into the rotor motion equation, enhances the system damping, and effectively suppresses the frequency overshoot problem, in the 9th issue of 2019, the "VSG active control based on angular frequency deviation compensation" of Power Grid Technology adjusts the active power output of VSG by compensating the angular frequency deviation, and improves the speed of VSG following the change of active power instruction.

[0005] Although the above methods can alleviate the overshoot problem, they cannot well balance the requirements of parameter smooth adjustment and system fast response, and the VSG has problems such as power overshoot and frequency oscillation when the light storage system is disturbed.

[0006] Therefore, how to provide a VSG coordinated control strategy to suppress power overshoot and frequency deviation, realize smooth adjustment of the moment of inertia and optimization of the dynamic performance of the VSG, and enhance the response speed and stability of the system is a problem that those skilled in the art need to solve. SUMMARY

[0007] Therefore, the present application provides a VSG coordinated control method and device based on improved adaptive and feedforward compensation to solve the technical problems mentioned in the background art.

[0008] In order to achieve the above-mentioned purpose, the present application adopts the following technical scheme:

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

[0010] S1. According to the model basis of the optical storage micro-grid and the dynamic response characteristics under different working conditions, the model of the VSG optical storage grid-connected system including the hybrid storage unit and the inverter is established, and the power angle characteristics and frequency oscillation curve are analyzed;

[0011] S2. The power angle and angular frequency of the VSG are divided into multiple intervals, the angular velocity variation characteristics caused by the input power variation in each interval are analyzed, the adjustment direction of the moment of inertia and the damping coefficient is determined, and the improved adaptive control equation is designed by using the continuous and derivable characteristics of the arctangent function, so that smooth adjustment of the two is realized.

[0012] S3. A feedforward compensation link is added to the VSG controller, the collected grid frequency or power disturbance signal is superimposed on the active power reference value, early adjustment is realized, and the improved adaptive control works cooperatively; the active compensation expression and the rotor motion equation of the AFC-VSG are established, the compensation coefficient and the filter time constant are set coordinately, and the zero-pole pair configuration is optimized.

[0013] S4. Real-time data is collected, the power reference value is corrected in advance based on the feedforward compensation control strategy by predicting frequency fluctuation, and the virtual moment of inertia and the damping coefficient of the VSG are adjusted based on the optimized adaptive control strategy, so that dynamic matching of the two under different working conditions is realized, and the deviation caused by frequency and power disturbance is suppressed.

[0014] Preferably, step S1 specifically comprises:

[0015] The rotor motion equivalent equation, the active ring control equation and the reactive ring control equation of the synchronous generator are established.

[0016] The closed-loop transfer function of the VSG active ring is derived in combination with the small signal model analysis method of the traditional synchronous generator.

[0017] The natural oscillation angular frequency and the damping ratio are determined.

[0018] Based on the under-damped state of the system, the maximum overshoot of the power angle and the regulation time of the synchronous generator are analyzed.

[0019] Preferably, in step S1, when the micro-grid is normally operated, the motion equation of the rotor is equivalent to:

[0020]

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

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

[0023] P m = P ref -K f (ω-ω0)

[0024] Wherein, P ref is the reference value of the active power, K f is the primary frequency modulation coefficient;

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

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

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

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

[0029]

[0030] Wherein, X is the equivalent reactance of the line;

[0031] The natural oscillation angular frequency ω n and the damping ratio ξ are:

[0032]

[0033] The maximum overshoot and the regulation time are:

[0034]

[0035] Preferably, the step S2 introduces the inverse tangent function optimized adaptive control strategy, which is specifically:

[0036]

[0037] Wherein, J0 and D0 are the moment of inertia and the damping coefficient of the system in the initial stable state, K j is the adjustment coefficient of the moment of inertia, and Kd is the adjustment coefficient of damping coefficient, T j is the threshold of angular velocity change rate, T d is the threshold of frequency change, K Δ ω is the frequency compensation coefficient.

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

[0039]

[0040] wherein, K AFC is the compensation coefficient of the AFC-VSG, T f is the filter time constant.

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

[0042]

[0043] wherein,

[0044]

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

[0046]

[0047] The adjustment coefficient K j of the moment of inertia and the adjustment coefficient K d of the damping coefficient satisfy the condition:

[0048]

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

[0050] A processing terminal, comprising a memory and a processor, the memory storing a computer program executable on the processor, and the processor implementing the VSG coordination control method based on the improved adaptive and feedforward compensation when executing the computer program.

[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 value 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 typically 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 parameters of the VSG can be adjusted according to real-time conditions, enabling the 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 locus of J and D when they change is 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 link, 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 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.

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: 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. The active power loop control equation of the VSG is: P m =P ref -K f (oh-oh0) 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: E=E0+K n (Q ref -Q)+K u (U ref -U) 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. The closed-loop transfer function of the VSG active power loop is: Where X is the line equivalent reactance; Natural oscillation frequency ω n The damping ratio ξ is: 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, 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. Δ ω is the frequency compensation coefficient.

5. The VSG coordinated control method based on improved adaptive and feedforward compensation according to claim 1, characterized in that, 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 This is the filtering time constant.

6. 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, 7. The VSG coordinated control method based on improved adaptive and feedforward compensation according to claim 5, 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:

8. 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.

9. 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 1-8.

10. 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 1-8.

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