A reactive power and voltage coordinated control method for new energy station based on active disturbance feedforward

Abstract

The present application relates to a kind of active disturbance feedforward-based reactive power voltage coordination control method of new energy station, belong to new energy grid-connected and power electronic control technical field.Solve feedback regulation action lag, active disturbance information is not fully utilized and the problem that energy storage reactive power regulation capability is not fully played out.Method is applied to the new energy station containing wind power, photovoltaic and energy storage branch, and energy storage adopts network type control.Wind power and photovoltaic steady state and real-time active power are calculated disturbance, and based on the voltage of common grid connection point, the voltage sensitivity coefficient of wind power active, photovoltaic active and energy storage reactive power is determined feedforward coefficient and compensation amount.According to the deviation of voltage target value and measured voltage, the feedback reactive correction amount is obtained by proportional integral.The feedforward reactive compensation amount and feedback reactive correction amount are added to obtain the energy storage reactive reference value, which is sent into the network type controller after limiting to adjust the output.The effect is to adjust reactive power in advance to reduce lag, match disturbance influence degree, feedback correction to improve accuracy and increase robustness, and enhance voltage suppression capability.

Description

Technical Field

[0001] This invention belongs to the field of new energy grid connection and power electronic control technology, and relates to a reactive voltage coordination control method for new energy power plants based on active power disturbance feedforward. Background Technology

[0002] With the continuous growth of installed capacity of new energy power generation, the proportion of new energy power plants such as wind power and photovoltaic power stations in the power system is constantly increasing. Large-scale new energy power plants are usually connected to the end of the grid or in areas with weak support, and are characterized by long collection lines and high grid impedance. When the short-circuit capacity of the external power grid is low, the power output fluctuation of the power plant can easily cause voltage deviation at the common grid connection point, resulting in insufficient reactive power support or voltage exceeding the limit.

[0003] Wind and solar power output is affected by natural conditions such as wind speed and sunlight, exhibiting randomness and volatility. When the active power of wind or solar power changes rapidly, the power flow, branch current, and line voltage drop within the power station change accordingly. These changes are transmitted to the common grid connection point through the collecting lines, step-up transformers, and grid connection impedance, thereby causing voltage fluctuations at the common grid connection point.

[0004] Existing reactive power voltage control at renewable energy power plants typically relies on feedback regulation based on the deviation between the voltage at the common grid connection point and the target value. While this type of feedback control is simple in structure and can improve steady-state error, the control action only occurs after the voltage deviation has formed. In scenarios with rapid fluctuations in active power from wind and solar power, it is prone to response lag and difficulty in timely suppressing transient deviations in the voltage at the common grid connection point.

[0005] Existing voltage control methods for renewable energy power plants include reactive power optimization allocation, voltage limit control, multi-timescale coordinated control, and model predictive control. These methods can improve grid-connected voltage quality to some extent, but they do not pay enough attention to short-term voltage disturbances caused by rapid changes in wind and solar active power. The active power disturbance information of wind power, active power disturbance information of solar power, and the rapid reactive power regulation capability of energy storage branches have not been fully utilized in a coordinated manner.

[0006] Energy storage converters are characterized by fast response and flexible adjustment. Energy storage branches using grid-connected control can also provide strong voltage support capabilities. Therefore, a reactive power and voltage control method for new energy power plants is needed. This method utilizes active power disturbance information from wind and solar power to generate reactive power compensation for energy storage in advance, and uses voltage feedback from the common grid connection point to correct compensation errors, thus balancing voltage regulation speed and steady-state control accuracy. Summary of the Invention

[0007] In view of this, the purpose of this invention is to provide a reactive power and voltage coordination control method for new energy power plants based on active power disturbance feedforward, so as to solve the problems of existing feedback regulation having action lag, insufficient utilization of active power disturbance information of wind power and photovoltaic power, and insufficient utilization of reactive power regulation capability of energy storage branch.

[0008] To achieve the above objectives, the present invention provides the following technical solution: A reactive power and voltage coordinated control method for new energy power plants based on active power disturbance feedforward is applied to a new energy power plant including wind power branches, photovoltaic branches, and energy storage branches. The wind power branches, photovoltaic branches, and energy storage branches converge at a common grid connection point, and the energy storage branches employ grid-based control. The method is characterized by the following steps: Obtain the steady-state active power of wind power and steady-state active power of photovoltaic power at a preset steady-state operating point. Also obtain the real-time active power of wind power, real-time active power of photovoltaic power, common grid connection point voltage, and the target value of the common grid connection point voltage. Determine the wind power active power disturbance ΔPw based on the difference between the real-time active power of wind power and the steady-state active power of wind power. Similarly, determine the photovoltaic active power disturbance ΔP based on the difference between the real-time active power of photovoltaic power and the steady-state active power of photovoltaic power. pv ; Near the preset steady-state operating point, the voltage sensitivity coefficients of the common grid connection point voltage to wind power active power, photovoltaic active power, and energy storage reactive power are obtained respectively, and the three voltage sensitivity coefficients are denoted as follows: U PCC / P w , U PCC / P pv and U PCC / Q ess ; The wind power feedforward coefficient K is determined according to the following formula. w and photovoltaic feedforward coefficient K pv : K w = ( U PCC / P w ) / ( U PCC / Q ess ); K pv = ( U PCC / Ppv ) / ( U PCC / Q ess ); The feedforward reactive power compensation amount Q is determined according to the following formula. ff * : Q ff * =K w ·ΔP w +K pv ·ΔP pv ; The feedback reactive power correction amount is obtained by performing proportional-integral adjustment based on the difference between the target value of the common grid connection point voltage and the common grid connection point voltage. The feedforward reactive power compensation amount and the feedback reactive power correction amount are added to obtain the energy storage reactive power reference value. The energy storage reactive power command value is determined based on the energy storage reactive power reference value, and the energy storage reactive power command value is input into the grid-type controller of the energy storage branch to adjust the reactive power output of the energy storage branch.

[0009] Furthermore, the wind power branch, the photovoltaic branch, and the energy storage branch each include a converter, a step-up transformer, and an equivalent circuit connected in sequence. The equivalent circuit is connected to the common grid connection point, which is connected to the external power grid via the main transformer.

[0010] Furthermore, in the first-order linearized model of the preset steady-state operating point, the change in the voltage at the common grid connection point is determined according to the following formula: ΔU PCC =( U PCC / P w )·ΔP w +( U PCC / P pv )·ΔP pv +( U PCC / Q ess )·ΔQ ess ; Wherein, ΔU PCC ΔP is the change in voltage at the common grid connection point. w Let ΔP be the disturbance to the active power of the wind power. pv Let ΔQ be the disturbance of the photovoltaic active power. ess This represents the change in reactive power of energy storage. U PCC / P w The voltage sensitivity coefficient of the common grid connection point voltage to the active power of the wind power is given. U PCC / P pv The voltage sensitivity coefficient of the common grid connection point voltage to the photovoltaic active power is given. U PCC / Q ess The voltage sensitivity coefficient of the common grid connection point voltage to the energy storage reactive power.

[0011] Furthermore, the wind power active power disturbance and the photovoltaic active power disturbance are determined according to the following formulas: ΔP w =P w P w0 ; ΔP pv =P pv P pv0 ; Among them, P w P represents the real-time active power of the wind power. w0 Let P be the steady-state active power of the wind power. pv P represents the real-time active power of the photovoltaic system. pv0 The photovoltaic steady-state active power is denoted as .

[0012] Furthermore, the voltage sensitivity coefficient is obtained through disturbance testing or simulation identification. Wind power active power disturbance, photovoltaic active power disturbance and energy storage reactive power disturbance are applied near the preset steady-state operating point, and the coefficient is calculated based on the voltage response of the common grid connection point corresponding to each disturbance.

[0013] Furthermore, before determining the wind power active power disturbance and the photovoltaic active power disturbance, the acquired real-time wind power and the real-time photovoltaic active power are filtered, and the filtered wind power active power and the filtered photovoltaic active power are used to determine the corresponding active power disturbance.

[0014] Furthermore, the feedback reactive power correction amount is determined according to the following formula: e U =U PCC * U PCC ; Q fb * =K p ·e U +Ki ·∫ e U dt; Among them, e U For the voltage deviation at the common grid connection point, U PCC * U is the target voltage value at the common grid connection point. PCC Q is the voltage at the common grid connection point. fb * K is the feedback reactive power correction amount. p K is the proportionality coefficient. i is the integral coefficient.

[0015] Furthermore, before inputting the energy storage reactive power command value into the grid-type controller, the energy storage reactive power reference value is limited according to the reactive power capacity of the energy storage branch. The energy storage reactive power reference value and the limited energy storage reactive power command value are determined according to the following formulas: Q ess * =Q ff * +Q fb * ; Q ess,cmd * =sat(Q ess * ); Among them, Q ff * Q is the feedforward reactive power compensation amount. fb * Q is the feedback reactive power correction amount. ess * Q is the reference value for the energy storage reactive power. ess,cmd * The reactive power command value for energy storage is denoted as sat, where sat is the limiting operation performed based on the reactive power capacity of the energy storage branch.

[0016] Furthermore, both the wind power branch and the photovoltaic branch adopt grid-following control, which tracks the voltage phase of the common grid connection point through a phase-locked loop, and realizes active power and reactive power output through current control.

[0017] The beneficial effects of this invention are as follows: (1) Based on the active power disturbance of wind power and the active power disturbance of photovoltaic power, the feedforward reactive power compensation amount is generated so that the energy storage branch can adjust the reactive power output before the voltage deviation at the common grid connection point is significantly formed, thereby reducing the response lag caused by simply using voltage feedback regulation.

[0018] (2) Using the voltage sensitivity coefficients of the common grid connection point voltage to the active power of wind power, the active power of photovoltaic power and the reactive power of energy storage respectively, establish the mapping relationship between the disturbance of active power of wind power and photovoltaic power and the compensation of reactive power of energy storage, so that the amount of feedforward reactive power compensation matches the degree of influence of different disturbance sources on the voltage of the common grid connection point.

[0019] (3) By superimposing feedback reactive power correction on the basis of feedforward reactive power compensation, the voltage sensitivity coefficient approximation error, operating state change, parameter deviation and residual voltage deviation caused by system nonlinearity can be dynamically corrected, thereby improving the steady-state control accuracy and control robustness of the common grid connection point voltage.

[0020] (4) The grid-type controller of the energy storage branch is input after the energy storage reactive power reference value is limited. There is no need to change the underlying control structure of the grid-type controller. Only active disturbance feedforward and voltage feedback coordination links need to be added to the outer layer, which is convenient for implementation in new energy power plants.

[0021] (5) Under the same wind speed and light disturbance conditions, simulation results show that the present invention can reduce the maximum deviation and integral absolute error of the common grid connection point voltage and improve the voltage smoothing capability of the common grid connection point of new energy power plants.

[0022] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0023] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein: Figure 1 This is a schematic diagram of the grid connection structure of a new energy power station in an embodiment of the present invention; Figure 2 This is a diagram of the reactive voltage coordination control structure in an embodiment of the present invention; Figure 3 The above are the new energy output fluctuation curves used in the embodiments of the present invention, wherein (a) is the wind speed variation curve and (b) is the solar radiation amplitude variation curve. Figure 4 These are the common grid connection point voltage response curves under different control strategies in the embodiments of the present invention; Figure 5 The figures show the reactive power output curves of energy storage under different control strategies in the embodiments of the present invention. Detailed Implementation The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0024] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual images. They should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0025] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0026] I. Grid Connection Structure of New Energy Power Stations like Figure 1 As shown, the new energy power station in this embodiment includes a wind power branch, a photovoltaic branch, and an energy storage branch. The wind power branch, photovoltaic branch, and energy storage branch are respectively connected to the Point of Common Coupling (PCC) via corresponding converters, step-up transformers, and equivalent lines. The PCC is connected to the external power grid via the main transformer.

[0027] In this embodiment, the wind power branch, photovoltaic branch and energy storage branch are all connected to a common grid connection point with a voltage level of 33kV through a 690V / 33kV step-up transformer. The common grid connection point is then connected to the external power grid through a 33kV / 220kV main transformer. Figure 1 Middle,U G Z represents the equivalent voltage of the external power grid. G Z represents the equivalent impedance of the external power grid. W Z PV and Z ESSThese represent the equivalent line impedances of the wind power branch, photovoltaic branch, and energy storage branch, respectively.

[0028] Both the wind power branch and the photovoltaic branch adopt grid-following control, tracking the voltage phase of the common grid connection point through a phase-locked loop, and realizing active and reactive power output through current control. The active power of wind power varies with wind speed, and the active power of photovoltaic power varies with sunlight. Therefore, the wind power branch and the photovoltaic branch serve as the sources of active power disturbance in this embodiment.

[0029] The energy storage branch adopts grid-type control and serves as the execution unit for reactive power and voltage regulation at the common grid connection point. The energy storage branch receives the reactive power command value generated by the outer reactive power and voltage control loop, and the grid-type controller regulates the reactive power output of the energy storage branch.

[0030] II. Determination of Voltage Sensitivity Coefficient This embodiment first determines the impact of changes in active and reactive power on the voltage at the common grid connection point near a preset steady-state operating point. Under small disturbance conditions, the change in the voltage at the common grid connection point can be approximated as: ΔU PCC ≈S UP ·ΔP+S UQ ·ΔQ(1) In the formula, ΔU PCC S represents the change in voltage at the common grid connection point, ΔP and ΔQ represent the changes in active power and reactive power of the renewable energy power plant, respectively. UP and S UQ These represent the sensitivity of the common grid connection point voltage to active power and reactive power, respectively.

[0031] against Figure 1 The wind-solar-storage new energy power station shown, in the first-order linearized model of the preset steady-state operating point, takes the active power of wind power, the active power of photovoltaic power, and the reactive power of energy storage as inputs, and the change in voltage at the common grid connection point is expressed as: ΔU PCC =( U PCC / P w )·ΔP w +( U PCC / P pv )·ΔP pv +( U PCC / Q ess )·ΔQ ess (2) In the formula, ΔP w Let ΔP be the active power disturbance of wind power.pv Let ΔQ be the disturbance of photovoltaic active power. ess This represents the change in reactive power of energy storage. U PCC / P w This is the voltage sensitivity coefficient of the public grid connection point voltage to the active power of wind power. U PCC / P pv This is the voltage sensitivity coefficient of the public grid connection point voltage to the photovoltaic active power. U PCC / Q ess This is the voltage sensitivity coefficient of the common grid connection point voltage to the reactive power of energy storage.

[0032] The three voltage sensitivity coefficients mentioned above can be obtained through disturbance tests or simulations. Specifically, small disturbances in wind power active power, photovoltaic active power, and energy storage reactive power are applied near a preset steady-state operating point, and the voltage response at the common grid connection point corresponding to each disturbance is recorded. Each time a disturbance is applied, other input quantities are kept constant or maintained at their corresponding steady-state values, and the corresponding voltage sensitivity coefficient is calculated based on the ratio of the disturbance quantity to the voltage response at the common grid connection point.

[0033] For example, using δP respectively w δP pv and δQ ess This represents the small disturbances in active power from wind power, active power from photovoltaic power, and reactive power from energy storage applied during the identification process, expressed as ΔU. PCC,w , ΔU PCC,pv and ΔU PCC,ess Let represent the voltage response at the corresponding common grid connection point. Then, the three voltage sensitivity coefficients can be approximately calculated using the following formula: U PCC / P w ≈ΔU PCC,w / δP w (3) U PCC / P pv ≈ΔU PCC,pv / δP pv (4) U PCC / Q ess ≈ΔU PCC,ess / δQ ess (5) The three voltage sensitivity coefficients obtained in this way all correspond to the same preset steady-state operating point, so that the wind power feedforward coefficient and the photovoltaic feedforward coefficient have a unified calculation benchmark.

[0034] III. Active Disturbance Feedforward Compensation Obtain the steady-state active power P of wind power at the preset steady-state operating point w0 and photovoltaic steady-state active power P pv0 And obtain the real-time active power P of wind power. w Real-time active power P of photovoltaic pv The active power disturbances of wind power and photovoltaic power are determined according to the following formulas: ΔP w =P w P w0 (6) ΔP pv =P pv P pv0 (7) The active power disturbances of wind power and photovoltaic power are used as feedforward inputs, so that the feedforward channel responds to the change in active power relative to the preset steady-state operating point, rather than directly responding to the absolute active power level.

[0035] To offset the voltage changes at the common grid connection point caused by active power disturbances from wind power and photovoltaic power using changes in reactive power from energy storage, the sum of the active power disturbance term from wind power, the active power disturbance term from photovoltaic power, and the reactive power compensation term from energy storage is made zero in the first-order linearized model, i.e.: ( U PCC / P w )·ΔP w +( U PCC / P pv )·ΔP pv +( U PCC / Q ess )·Q ff * ≈0 (8) The feedforward reactive power compensation amount Q is determined according to the above formula. ff * : Q ff * =K w ·ΔP w +K pv ·ΔP pv (9) In the formula, K w K is the wind power feedforward coefficient. pv This refers to the photovoltaic feedforward coefficient. The wind power feedforward coefficient and the photovoltaic feedforward coefficient are determined by the negative ratio of the corresponding active power voltage sensitivity coefficient to the reactive power voltage sensitivity coefficient of energy storage. K w = ( U PCC / P w ) / ( U PCC / Q ess (10) K pv = ( U PCC / P pv ) / ( U PCC / Q ess (11) The negative sign in the feedforward coefficient is used to ensure that the reactive power adjustment direction of the energy storage branch is opposite to the direction of the voltage change at the common grid connection point caused by active power disturbances from wind power and photovoltaics. The values ​​and signs of the three voltage sensitivity coefficients are determined by the identification results near the same preset steady-state operating point.

[0036] To reduce the impact of measurement noise on active power disturbances, the real-time active power of wind power and photovoltaic power can be filtered before determining their disturbances. The filtered active power and photovoltaic power are then subtracted from their corresponding steady-state active power values. The filtering parameters are set based on the power measurement noise and the required dynamic response speed.

[0037] IV. Voltage Feedback Correction at Common Grid Connection Point The feedforward reactive power compensation can adjust the energy storage reactive power in advance according to the active power disturbance. However, the voltage sensitivity coefficient is determined based on the first-order linearization relationship near the preset steady-state operating point. Changes in operating state, parameter deviations, and system nonlinearity may cause compensation errors. Therefore, this embodiment further utilizes the common grid connection point voltage for feedback correction.

[0038] Obtain the target voltage value U at the common grid connection point PCC * and the voltage U at the public grid connection point PCC The voltage deviation e at the common grid connection point is determined according to the following formula. U : e U =UPCC * U PCC (12) The proportional-integral regulation is applied to the voltage deviation at the common grid connection point to obtain the feedback reactive power correction quantity Q. fb * : Q fb * =K p ·e U +K i ·∫ e U dt(13) In the formula, K p K is the proportionality coefficient. i These are the integral coefficients. The proportional term is used to quickly generate a correction based on the current common grid connection point voltage deviation, while the integral term is used to reduce the steady-state residual deviation.

[0039] V. Coordinated Implementation of Feedforward Compensation and Feedback Correction like Figure 2 As shown, the feedforward reactive power compensation amount Q ff * With feedback reactive power correction Q fb * Adding them together, we obtain the reference value Q for the energy storage reactive power. ess * : Q ess * =Q ff * +Q fb * (14) The reactive power reference value of energy storage is limited based on the reactive power capacity of the energy storage branch to obtain the reactive power command value Q of energy storage. ess,cmd * : Q ess,cmd * =sat(Q ess * (15) In the formula, *sat* represents the limiting calculation performed based on the reactive power capacity of the energy storage branch. Let the lower and upper limits of the reactive power output allowed by the energy storage branch be Q, respectively. ess,min and Q ess,max Then the limiting operation can be expressed as: when Q ess * Less than Q ess,min When, make Q ess,cmd * equals Q ess,min When Q ess * Located in Qess,min With Q ess,max In between, make Q ess,cmd * equals Q ess * When Q ess * Greater than Q ess,max When, make Q ess,cmd * equals Q ess,max .

[0040] The reactive power command value of the energy storage branch is input into the grid-type controller of the energy storage branch, and the grid-type controller adjusts the reactive power output of the energy storage branch. This control structure sets an active power disturbance feedforward compensation channel and a common grid connection point voltage feedback correction channel on the outer layer of the grid-type controller, without changing the underlying control structure of the grid-type controller.

[0041] The feedforward reactive power compensation is used to improve the response speed to active power disturbances from wind power and photovoltaics, while the feedback reactive power correction is used to correct the feedforward compensation error. Together, they form the energy storage reactive power reference value, thus enabling the reactive power output of the energy storage branch to have both fast response capability and steady-state correction capability.

[0042] VI. Simulation Verification To verify the effectiveness of the method described in this invention, a grid-connected simulation model of a wind-solar-storage renewable energy power station was built on the MATLAB / Simulink platform. The model includes a wind power branch, a photovoltaic branch, an energy storage branch, a 33kV common grid connection point, a step-up grid connection link, and an equivalent portion of the external power grid. The wind power branch, photovoltaic branch, and energy storage branch are connected to the 33kV common grid connection point via 690V / 33kV step-up transformers, and the common grid connection point is then connected to the external power grid via a 33kV / 220kV main transformer.

[0043] To construct scenarios of active power fluctuations in wind and solar power, random variations in wind speed and solar illumination were set, with a signal update step of 0.05s and a total simulation duration of 6s. The initial steady-state phase was from 0 to 1s, the disturbance phase of renewable energy output was from 1 to 5s, and the recovery and maintenance phase was from 5 to 6s after the disturbance ended. After the disturbance ended, wind speed and solar illumination returned to their initial operating conditions. Figure 3 (a) and (b) in the figure show the wind speed variation curve and the light intensity variation curve, respectively.

[0044] The target voltage at the common grid connection point is set to 1.0 pu, corresponding to an actual voltage of 33 kV. The voltage response curve at the common grid connection point is expressed in per-unit values. The maximum deviation and integral absolute error are calculated based on the actual voltage at the common grid connection point, and the statistical window for the indicators is 1–5 s.

[0045] Maximum voltage deviation ΔV at common grid connection pointmax Defined as the actual value of the voltage at the common grid connection point within the statistical window, V. PCC (t) relative to the reference voltage V ref The maximum absolute deviation, where t1 and t2 are the start and end times of the statistical window for the indicator, respectively: ΔV max =max t∈[t1,t2] |V PCC (t) V ref |(16) The integral absolute error (IAE) is defined as the time integral of the absolute value of the difference between the actual voltage at the common grid connection point and the reference voltage within the statistical window. IAE=∫ t1 t 2|V PCC (t) V ref |dt(17) Recovery time is calculated starting 5 seconds after the disturbance ends. The system is considered fully recovered once the voltage at the common grid connection point enters the error band near the reference value and remains there for a preset time. In this embodiment, the recovery criterion bandwidth is 10. -4 The continuous holding time is 0.1s.

[0046] This embodiment obtains the wind power feedforward coefficient K by applying a small disturbance near a preset steady-state operating point through simulation identification. w and photovoltaic feedforward coefficient K pv The proportional coefficient K was tuned through simulation. p and integral coefficient K i To balance the dynamic response and steady-state error suppression of the common grid connection point voltage, the main control parameters are shown in Table 1.

[0047] Table 1 Main control parameters of the simulation system

[0048] Three control strategies were compared under the same wind speed and solar radiation disturbance conditions. Strategy A was no additional control, meaning the energy storage branch did not engage any additional reactive power compensation for voltage fluctuations at the common grid connection point; Strategy B was active power disturbance feedforward compensation control, which generated reactive power compensation for energy storage based on the active power disturbances of wind power and photovoltaic power; Strategy C was the control strategy combining feedforward compensation and voltage feedback correction of this invention, which introduced a proportional-integral feedback loop for the common grid connection point voltage based on Strategy B.

[0049] Figure 4The diagram illustrates the voltage response at the common grid connection point (CBP) under three control strategies. Under Strategy A, the CBP voltage is significantly affected by fluctuations in wind and solar power output, exhibiting substantial voltage fluctuations during disturbance phases. Strategy B utilizes wind and solar active power disturbance information to generate feedforward reactive power compensation in advance, significantly reducing the amplitude of CBP voltage fluctuations. Strategy C, based on feedforward compensation, uses the CBP voltage deviation for feedback correction, further bringing the CBP voltage closer to the target value.

[0050] Figure 5 The diagram illustrates the reactive power output of energy storage under three control strategies. In Strategy A, no additional reactive power compensation control is applied to the energy storage branch, resulting in a small fluctuation in the reactive power output. In Strategy B, the reactive power of energy storage can be rapidly adjusted in response to disturbances in the active power of wind and solar power. Strategy C adds a feedback reactive power correction to Strategy B, enabling the reactive power output of energy storage to have both rapid response and error correction capabilities.

[0051] The maximum deviation of the common grid connection point voltage, integral absolute error, and recovery time under the three control strategies are shown in Table 2.

[0052] Table 2 Comparison of voltage stabilization effects under different control strategies

[0053] Compared to Strategy A, Strategy B reduced the maximum deviation of the common grid connection point voltage from 319V to 97.9V, a reduction of 69.31%; the integral absolute error decreased from 360.5V·s to 123V·s, a reduction of 65.88%; and the recovery time shortened from 0.1310s to 0.1228s. These results demonstrate that active power disturbance feedforward compensation can utilize wind and photovoltaic active power disturbance information to proactively adjust the reactive power output of energy storage, thereby reducing the common grid connection point voltage deviation.

[0054] Compared to Strategy A, Strategy C reduces the maximum deviation of the common grid connection point voltage by 74.23% and the integral absolute error by 74.29%. Compared to Strategy B, Strategy C further reduces the maximum deviation of the common grid connection point voltage by 16.04% and the integral absolute error by 24.65%. The recovery time of Strategy C is 0.1238s, which is close to that of Strategy B, while further improving in terms of voltage deviation amplitude and cumulative error.

[0055] The simulation results above show that feedforward reactive power compensation can improve the response speed of the energy storage branch to wind and photovoltaic active power disturbances, and common grid connection point voltage feedback can correct the feedforward compensation error; the combination of the two can improve the control accuracy of the common grid connection point voltage while maintaining a fast response.

[0056] This invention is not limited to the specific parameters shown in the above embodiments. For new energy power stations with different capacities, different access voltage levels, or different grid strengths, three voltage sensitivity coefficients can be re-identified near the corresponding preset steady-state operating point, and the wind power feedforward coefficient and photovoltaic feedforward coefficient can be determined accordingly; the proportional coefficient, integral coefficient, and limiting range can be set according to the reactive power capacity of the corresponding energy storage branch and the voltage control requirements of the common grid connection point.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A reactive power and voltage coordinated control method for new energy power plants based on active power disturbance feedforward, characterized in that: An application to new energy power stations including wind power branches, photovoltaic branches, and energy storage branches, wherein the wind power branches, photovoltaic branches, and energy storage branches converge at a common grid connection point, and the energy storage branches adopt grid-based control, characterized by including the following steps: Obtain the steady-state active power of wind power and steady-state active power of photovoltaic power at a preset steady-state operating point. Also obtain the real-time active power of wind power, real-time active power of photovoltaic power, common grid connection point voltage, and the target value of the common grid connection point voltage. Determine the wind power active power disturbance ΔPw based on the difference between the real-time active power of wind power and the steady-state active power of wind power. Similarly, determine the photovoltaic active power disturbance ΔP based on the difference between the real-time active power of photovoltaic power and the steady-state active power of photovoltaic power. pv ; Near the preset steady-state operating point, the voltage sensitivity coefficients of the common grid connection point voltage to wind power active power, photovoltaic active power, and energy storage reactive power are obtained respectively, and the three voltage sensitivity coefficients are denoted as follows: U PCC / P w , U PCC / P pv and U PCC / Q ess ; The wind power feedforward coefficient K is determined according to the following formula. w and photovoltaic feedforward coefficient K pv : K w = ( U PCC / P w ) / ( U PCC / Q ess ); K pv = ( U PCC / P pv ) / ( U PCC / Q ess ); The feedforward reactive power compensation amount Q is determined according to the following formula. ff * : Q ff * =K w ·ΔP w +K pv ·ΔP pv ; The feedback reactive power correction amount is obtained by performing proportional-integral adjustment based on the difference between the target value of the common grid connection point voltage and the common grid connection point voltage. The feedforward reactive power compensation amount and the feedback reactive power correction amount are added to obtain the energy storage reactive power reference value. The energy storage reactive power command value is determined based on the energy storage reactive power reference value, and the energy storage reactive power command value is input into the grid-type controller of the energy storage branch to adjust the reactive power output of the energy storage branch.

2. The reactive power and voltage coordinated control method for new energy power plants based on active power disturbance feedforward according to claim 1, characterized in that, The wind power branch, the photovoltaic branch, and the energy storage branch each include a converter, a step-up transformer, and an equivalent circuit connected in sequence. The equivalent circuit is connected to the common grid connection point, which is connected to the external power grid via the main transformer.

3. The reactive power and voltage coordinated control method for new energy power plants based on active power disturbance feedforward according to claim 1, characterized in that, In the first-order linearized model of the preset steady-state operating point, the change in the voltage at the common grid connection point is determined according to the following formula: DU PCC =( U PCC / P w )·ΔP w +( U PCC / P pv )·ΔP pv +( U PCC / Q ess )·ΔQ ess ; Where, ΔU PCC ΔP is the change in voltage at the common grid connection point. w Let ΔP be the active power disturbance of the wind power. pv Let ΔQ be the disturbance of the photovoltaic active power. ess This represents the change in reactive power of energy storage. U PCC / P w The voltage sensitivity coefficient of the common grid connection point voltage to the active power of the wind power is given. U PCC / P pv The voltage sensitivity coefficient of the common grid connection point voltage to the photovoltaic active power is given. U PCC / Q ess The voltage sensitivity coefficient of the common grid connection point voltage to the energy storage reactive power.

4. The reactive power and voltage coordinated control method for new energy power plants based on active power disturbance feedforward according to claim 1, characterized in that, The wind power active power disturbance and the photovoltaic active power disturbance are determined according to the following formulas: ΔP w =P w P w0 ; ΔP pv =P pv P pv0 ; Among them, P w P represents the real-time active power of the wind power. w0 Let P be the steady-state active power of the wind power. pv P represents the real-time active power of the photovoltaic system. pv0 The photovoltaic steady-state active power is denoted as .

5. The reactive power and voltage coordinated control method for new energy power plants based on active power disturbance feedforward according to claim 3, characterized in that, The voltage sensitivity coefficient is obtained through disturbance testing or simulation identification. Wind power active power disturbance, photovoltaic active power disturbance and energy storage reactive power disturbance are applied near the preset steady-state operating point, and the coefficient is calculated based on the voltage response of the common grid connection point corresponding to each disturbance.

6. The reactive power and voltage coordinated control method for new energy power plants based on active power disturbance feedforward according to claim 1, characterized in that, Before determining the wind power active power disturbance and the photovoltaic active power disturbance, the acquired real-time wind power and real-time photovoltaic active power are filtered, and the corresponding active power disturbance is determined using the filtered wind power active power and the filtered photovoltaic active power.

7. The reactive power and voltage coordinated control method for new energy power plants based on active power disturbance feedforward according to claim 1, characterized in that, The feedback reactive power correction amount is determined according to the following formula: yes U =U PCC * IN PCC ; Q fb * =K p ·e U +K i ·∫ e U dt; Among them, e U For the voltage deviation at the common grid connection point, U PCC * U is the target voltage value at the common grid connection point. PCC Q is the voltage at the common grid connection point. fb * K is the feedback reactive power correction amount. p K is the proportionality coefficient. i is the integral coefficient.

8. The reactive power and voltage coordinated control method for new energy power plants based on active power disturbance feedforward according to claim 1, characterized in that, Before inputting the energy storage reactive power command value into the grid-type controller, the energy storage reactive power reference value is limited according to the reactive power capacity of the energy storage branch. The energy storage reactive power reference value and the limited energy storage reactive power command value are determined according to the following formulas: Q ess * =Q ff * +Q fb * ; Q ess,cmd * =sat(Q ess * ); Among them, Q ff * Q is the feedforward reactive power compensation amount. fb * Q is the feedback reactive power correction amount. ess * Q is the reference value for the energy storage reactive power. ess,cmd * The reactive power command value for energy storage is denoted as sat, where sat is the limiting operation performed based on the reactive power capacity of the energy storage branch.

9. The reactive power and voltage coordinated control method for new energy power plants based on active power disturbance feedforward according to claim 2, characterized in that, Both the wind power branch and the photovoltaic branch adopt grid-following control, which tracks the voltage phase of the common grid connection point through a phase-locked loop, and realizes active power and reactive power output through current control.

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