A wind farm reactive voltage control method and system for preventing and controlling fault ride-through actions under large and rapid fluctuations in wind power output

Abstract

The present invention discloses a wind farm reactive voltage control method and system for preventing and controlling fault ride-through actions under large and rapid fluctuations in wind power output, and belongs to the field of new energy grid connection technology. The method of the present invention includes: establishing a wind farm group access grid model, generating a data file for simulation calculation based on the access grid model; establishing a reactive voltage control mode that coordinates the wind farm group's fixed-period steady-state reactive voltage control and the wind farm group's SVG equipment-level constant voltage response control; dynamically simulating the rapid and large-scale change characteristics of the wind farm group's output according to the data file, and obtaining simulation analysis results that have a dynamic impact on the wind power grid connection point and the wind turbine terminal voltage; and preventing and controlling fault ride-through actions under large and rapid fluctuations in wind power output. The present invention standardizes the actions of reactive equipment such as multiple SVGs and multiple wind turbines in wind farms, optimizes the reactive voltage control of wind farm groups under gradually increasing grid connection capacity and low short-circuit ratio, and promotes the acceptance of new energy.

Description

Technical Field

[0001] The present invention relates to the field of new energy grid connection technology, and more specifically, to a wind farm reactive voltage control method and system for preventing and controlling fault ride-through actions under large and rapid fluctuations in wind power output. Background Art

[0002] After being connected to the grid, a wind farm should meet operational objectives such as reactive power stratification and zoning balance, voltage safety, and voltage quality. According to the "Technical Regulations for Wind Farm Connection to the Power System," wind farms must be equipped with reactive power sources of a certain capacity and different types, including wind turbines capable of outputting reactive power and reactive compensation devices such as static VAR generators (SVGs). After a wind farm is put into operation, reactive power and voltage control must be performed to optimize the reactive power output of on-site wind turbines or reactive power sources such as SVGs. This ensures that the voltage amplitude and voltage fluctuation rate at the wind farm's grid connection point remain within reasonable ranges under various operating conditions, and that the on-site voltage meets upper and lower constraints. Furthermore, the wind farm should provide dynamic reactive power support to the grid based on grid demand, maintaining voltage stability and reliable operation of the wind farm's connected units.

[0003] Research on wind farm reactive voltage control has been conducted in the following areas, including: wind farm reactive voltage control modes and coordinated control modes with the main grid; wind farm reactive voltage control optimization models and control strategy solutions; 1) wind farm reactive voltage control with different control objectives and constraints; 2) wind farm reactive voltage coordinated control taking into account different reactive control methods, including wind turbines, dynamic reactive compensation, and other methods; 3) control strategy solution methods. In my country's three-level voltage control system, the reactive voltage of wind farm clusters generally falls under the regional voltage control level. The upper level of reactive voltage control usually takes grid losses, voltage quality, and voltage safety as optimization objectives, considers the coordination of various reactive sources, and optimizes the voltage control target value or range for each wind farm control bus (usually the grid-connected bus). The target voltage of the control bus is sent to each area containing a wind farm cluster to perform regional reactive voltage control. The control cycle is generally minute-level. Based on the active / reactive power and voltage conditions of the power grid in the control area, and taking into account controllable reactive sources such as wind farms, conventional generators, and various substations in the area, the reactive voltage optimization of this area is carried out. In addition to tracking the voltage of each wind farm grid connection point, the regional reactive voltage control containing the wind farm cluster can also consider more optimization objectives and constraints related to the wind farm to achieve refined coordinated control of the wind farm's reactive equipment. The content of this patent belongs to the technical field of regional reactive voltage control of wind farm clusters.

[0004] As wind power grid-connected capacity increases, wind power short-circuit ratios continue to decrease, and the "solid voltage" capacity of wind power access areas declines. Fault disturbances can lead to greater voltage fluctuations, easily causing voltage limits at the grid connection point and at the wind turbine terminals. Due to the limited voltage withstand and overload capacity of wind turbine power electronic equipment, wind turbines require high / low voltage fault ride-through control and protection. When a disturbance causes the terminal voltage to reach the fault ride-through threshold, dynamic reactive power and reactive power control activates to assist the wind turbine in successfully riding through the fault. However, if the fault disturbance is severe or the connected grid is weak, the wind turbine may still be unable to ride through the fault after a period of time. In this case, the fault ride-through protection activates and disconnects the wind turbine. Wind power output fluctuations can also be considered a disturbance, characterized by rapid, large, and intermittent variations. In the case of a weak grid, voltage fluctuations can occur dramatically. If the wind farm fails to implement timely and effective reactive power and voltage control, voltage fluctuations may trigger high / low voltage fault ride-through control and protection for the wind turbine, impacting grid stability. Therefore, as larger capacity wind power is connected to the grid in the future and the short-circuit ratio continues to decrease, preventing and controlling wind turbine fault ride-through is a major goal of wind farm reactive power and voltage control to further improve the reliability and safety of wind power grid-connected operation.

[0005] The main reactive power devices in a wind farm include wind turbines and SVGs. These two types of reactive power devices have different characteristics: ① The capacity of a single wind turbine is relatively small, while the number of wind turbines in a wind farm is large. A typical 300MW wind farm has a total of 48 wind turbines with a single capacity of 6.25MW, while SVGs are generally configured with around 2 to 3 sets, a relatively small number. ② The reactive power output of the wind turbine must be coordinated with the active power of the unit, while SVGs only output reactive power, which has relatively fewer regulation constraints and is more convenient to control. ③ The reactive voltage response time of the wind turbine converter is generally 20 to 60ms, while the reactive voltage response time of SVGs is generally around 20ms. Relatively speaking, SVGs are more adaptable to regulation under rapidly changing operating conditions. When wind power output in a weak power grid changes rapidly and significantly, the prevention and control of reactive voltage fluctuations that trigger wind power fault ride-through generally requires the reactive equipment of the wind farm to respond in a timely manner. The rapid reactive voltage control can be implemented by referring to the AVR constant voltage response control of thermal power plant units. That is, when the wind farm has sufficient reactive power, the reactive equipment adopts constant voltage response closed-loop control to track and control changes in the target bus voltage, automatically adjust the reactive output of the equipment, and maintain the control target bus voltage constant. However, wind farms are different from conventional thermal power plants. The reactive equipment on the farm is small in capacity, numerous in number, and is power electronic equipment. The autonomous response actions of multiple power electronic equipment under weak power grids and low short-circuit ratios have exposed some risks in actual operation. When formulating reactive power and voltage control strategies, the following must be taken into consideration: ① The reactive output of the reactive equipment's responsive control causes a large jump in operating conditions such as voltage. If the responsive control strategies and parameter settings of multiple sets of reactive equipment are mismatched and uncoordinated, the interaction between multiple devices may cause control oscillation problems such as frequent switching / action of equipment; ② The response actions of multiple power electronic equipment such as wind turbines or SVGs in wind farm groups, which have a ms-level or even faster time scale, are prone to excite broadband oscillations and other problems, posing hidden dangers to the safe and stable operation of the power grid. Therefore, under the condition of large and rapid changes in the output of wind farm groups in weak power grids, taking into account the prevention and control of dynamic and transient reactive voltage problems such as wind power fault ride-through and oscillation, and coordinating and integrating with the optimization of steady-state reactive voltage, the relevant wind farm reactive voltage control models, control modes and strategies still need to be further studied, so as to more fully coordinate and standardize the actions of multiple power electronic reactive equipment in wind farms, so as to achieve multiple goals such as further improving the economy, reliability and safety of wind power grid-connected reactive voltage operation. Summary of the Invention

[0006] To address the above issues, the present invention proposes a method for preventing and controlling fault ride-through actions under large and rapid fluctuations in wind power output, comprising:

[0007] Establishing a grid access model for a group of wind farms, and generating a data file for simulation calculation based on the grid access model;

[0008] Establish a reactive voltage control mode that coordinates the fixed-cycle steady-state reactive voltage control of the wind farm group with the fixed-voltage response control of the SVG equipment level of the wind farm group;

[0009] Based on the data file, dynamically simulate the rapid and large-scale change characteristics of the wind farm group output, and obtain simulation analysis results of the dynamic impact on the wind power grid connection point and the wind turbine terminal voltage;

[0010] Based on the simulation analysis results, it is determined whether the wind turbines in the wind farm group have experienced fault ride-through action. If so, the wind farm group is controlled using the reactive voltage control mode to prevent and control the fault ride-through action under large and rapid fluctuations in wind power output.

[0011] Optionally, establishing a wind farm group access grid model includes: establishing steady-state and transient equivalent aggregation models of the wind farm, and establishing a steady-state model and a transient model of the wind farm group accessing the main grid based on the steady-state and transient equivalent aggregation models of the wind farm.

[0012] Optionally, establishing steady-state and transient equivalent aggregation models of the wind farm, and establishing a steady-state model and a transient model of the wind farm group connected to the main grid based on the steady-state and transient equivalent aggregation models of the wind farm, including:

[0013] Based on the wind conditions, turbine types, and internal wiring forms within the wind farm, multiple wind turbines within the wind farm are aggregated to generate equivalent aggregate models for the wind farm's steady-state and transient states.

[0014] Based on the steady-state and transient equivalent aggregation models of the wind farm, the wind power unit transformer, internal cables, grid-connected step-up transformer, supporting SVG and grid-connected lines are modeled. The main grid with a close electrical distance to the wind farm is modeled in detail, and the remaining main grids are modeled in an equivalent simplified manner to generate a steady-state model and a transient model of the wind farm group connected to the main grid.

[0015] The optional reactive voltage control mode includes: reserving the dynamic reactive margin of the wind farm group SVG, and using the wind farm group SVG equipment-level constant voltage response control to track voltage changes, automatically calling out the reserved dynamic reactive margin of the wind farm group SVG for preventing and controlling fault ride-through actions, and performing fixed-period steady-state reactive voltage control of the wind farm group based on the remaining SVG capacity after reserving the dynamic reactive margin of the wind farm group SVG and the reactive output of the wind turbines.

[0016] Optionally, based on the data file, a dynamic simulation of the rapid and large-scale change characteristics of the wind farm group output is performed, including:

[0017] Determine the basic output of the wind farm group based on the data file Wind conditions and historical output of wind farm groups;

[0018] Based on the basic output of wind farm groups Based on the wind conditions and historical output of the wind farm group, the rapid and large changes in the output of the wind farm group are predicted;

[0019] Dynamically simulate the rapid and drastic changes in wind farm output.

[0020] Optional dynamic simulation results include: simulation curves of wind farm group output changes.

[0021] Optionally, based on the dynamic simulation results, obtain simulation analysis results, including:

[0022] Based on the dynamic simulation results, according to the basic output of the wind farm group The simulation determines the rapid and large-scale change characteristics of the wind farm group output under the operating status, and the dynamic impact on the wind power grid connection point and the voltage fluctuation of the wind turbine terminal. Based on the dynamic impact, the simulation curves and event information of the wind turbine fault ride-through action and the impact on the safety and stability of the power grid are determined.

[0023] Optional, operating status, including: reactive voltage and active phase angle.

[0024] Optionally, when simulating and determining the rapid and large-scale change characteristics of the wind farm group output and the dynamic impact of voltage fluctuations at the wind power grid connection point and wind turbine terminal, the wind turbine and SVG maintain the initial reactive power value unchanged.

[0025] Optionally, the method further includes: establishing a high / low voltage fault ride-through control and protection model for the wind turbine;

[0026] The typical envelope corresponding to the high / low voltage fault ride-through protection function of the wind turbine is discretized, and the action voltage threshold and duration are given for each discrete point. Multiple discrete points and the corresponding action voltage thresholds and durations are then entered into the high / low voltage fault ride-through protection model of the wind turbine.

[0027] Simulation is performed using the high / low voltage fault ride-through control and protection model of wind turbines.

[0028] Optionally, the simulation curves include: a wind turbine terminal voltage simulation curve, a wind turbine active power and reactive power simulation curve, a grid-connected point bus voltage simulation curve, and a grid-connected line active power and reactive power simulation curve.

[0029] Optional event information includes: event information of high / low voltage fault ride-through control and protection action of wind turbine.

[0030] Optionally, based on the simulation analysis results, it is determined whether the wind turbines in the wind farm group have experienced a fault ride-through action. If so, the wind farm group is controlled using the reactive voltage control mode to prevent and control the fault ride-through action under large and rapid fluctuations in wind power output, including:

[0031] Calculating SVG dynamic reactive power margin The wind farm group is controlled in the reactive voltage control mode, and the SVG dynamic reactive margin is adjusted according to the SVG dynamic reactive margin. Update the SVG reactive upper limit, and based on the updated SVG reactive upper limit, perform wind farm group output according to a fixed control cycle under the reactive voltage control model. The steady-state reactive voltage control model is modeled and solved, and the reactive output values ​​of wind turbines and SVGs obtained are regularly sent to wind farms. The dynamic reactive reserve reserved by SVG is used to prevent and control fault ride-through actions under large and rapid fluctuations in wind power output.

[0032] Optionally, based on the simulation analysis results, determine whether the wind turbines in the wind farm group have experienced fault ride-through action. If not, set the SVG dynamic reactive margin to =0, the wind farm group is controlled by the fixed-cycle steady-state reactive voltage control of the wind farm group, and the dynamic reactive margin is set according to the SVG being 0. Update the SVG reactive upper limit, and based on the updated SVG reactive upper limit, perform wind farm group output according to a fixed control cycle under the reactive voltage control model. The steady-state reactive power and voltage control model is modeled and solved, and the reactive power output values ​​of wind turbines and SVGs obtained by the solution are regularly sent to the wind farm.

[0033] On the other hand, the present invention also proposes a system for preventing and controlling fault ride-through actions under large and rapid fluctuations in wind power output, comprising:

[0034] The initialization unit is used to establish a grid access model for a wind farm group and generate a data file for simulation calculation based on the grid access model; establish a reactive voltage control mode that coordinates the fixed-period steady-state reactive voltage control of the wind farm group with the fixed voltage response control of the SVG equipment level of the wind farm group;

[0035] A simulation unit, configured to dynamically simulate the rapid and substantial changes in wind farm group output characteristics based on the data file, and obtain simulation analysis results of the dynamic impact on the wind power grid connection point and the wind turbine terminal voltage;

[0036] The control unit is used to determine whether the wind turbines in the wind farm group have experienced fault ride-through action based on the simulation analysis results. If so, the wind farm group is controlled in the reactive voltage control mode to prevent and control the fault ride-through action under large and rapid fluctuations in wind power output.

[0037] Optionally, establishing a wind farm group access grid model includes: establishing steady-state and transient equivalent aggregation models of the wind farm, and establishing a steady-state model and a transient model of the wind farm group accessing the main grid based on the steady-state and transient equivalent aggregation models of the wind farm.

[0038] Optionally, establishing steady-state and transient equivalent aggregation models of the wind farm, and establishing a steady-state model and a transient model of the wind farm group connected to the main grid based on the steady-state and transient equivalent aggregation models of the wind farm, including:

[0039] Based on the wind conditions, turbine types, and internal wiring forms within the wind farm, multiple wind turbines within the wind farm are aggregated to generate equivalent aggregate models for the wind farm's steady-state and transient states.

[0040] Based on the steady-state and transient equivalent aggregation models of the wind farm, the wind power unit transformer, internal cables, grid-connected step-up transformer, supporting SVG and grid-connected lines are modeled. The main grid with a close electrical distance to the wind farm is modeled in detail, and the remaining main grids are modeled in an equivalent simplified manner to generate a steady-state model and a transient model of the wind farm group connected to the main grid.

[0041] The optional reactive voltage control mode includes: reserving the dynamic reactive margin of the wind farm group SVG, and using the wind farm group SVG equipment-level constant voltage response control to track voltage changes, automatically calling out the reserved dynamic reactive margin of the wind farm group SVG for preventing and controlling fault ride-through actions, and performing fixed-period steady-state reactive voltage control of the wind farm group based on the remaining SVG capacity after reserving the dynamic reactive margin of the wind farm group SVG and the reactive output of the wind turbines.

[0042] Optionally, based on the data file, a dynamic simulation of the rapid and large-scale change characteristics of the wind farm group output is performed, including:

[0043] Determine the basic output of the wind farm group based on the data file Wind conditions and historical output of wind farm groups;

[0044] Based on the basic output of wind farm groups Based on the wind conditions and historical output of the wind farm group, the rapid and large changes in the output of the wind farm group are predicted;

[0045] Dynamically simulate the rapid and drastic changes in wind farm output.

[0046] Optional dynamic simulation results include: simulation curves of wind farm group output changes.

[0047] Optionally, based on the dynamic simulation results, obtain simulation analysis results, including:

[0048] Based on the dynamic simulation results, according to the basic output of the wind farm group The simulation determines the rapid and large-scale change characteristics of the wind farm group output under the operating status, and the dynamic impact on the wind power grid connection point and the voltage fluctuation of the wind turbine terminal. Based on the dynamic impact, the simulation curves and event information of the wind turbine fault ride-through action and the impact on the safety and stability of the power grid are determined.

[0049] Optional, operating status, including: reactive voltage and active phase angle.

[0050] Optionally, when simulating and determining the rapid and large-scale change characteristics of the wind farm group output and the dynamic impact of voltage fluctuations at the wind power grid connection point and wind turbine terminal, the wind turbine and SVG maintain the initial reactive power value unchanged.

[0051] Optionally, based on the dynamic simulation results, obtaining simulation analysis results also includes: establishing a high / low voltage fault ride-through control and protection model for the wind turbine;

[0052] The typical envelope corresponding to the high / low voltage fault ride-through protection function of the wind turbine is discretized, and the action voltage threshold and duration are given for each discrete point. Multiple discrete points and the corresponding action voltage thresholds and durations are then entered into the high / low voltage fault ride-through protection model of the wind turbine.

[0053] Simulation is performed using the high / low voltage fault ride-through control and protection model of wind turbines.

[0054] Optionally, the simulation curves include: a wind turbine terminal voltage simulation curve, a wind turbine active power and reactive power simulation curve, a grid-connected point bus voltage simulation curve, and a grid-connected line active power and reactive power simulation curve.

[0055] Optional event information includes: event information of high / low voltage fault ride-through control and protection action of wind turbine.

[0056] Optionally, based on the simulation analysis results, it is determined whether the wind turbines in the wind farm group have experienced a fault ride-through action. If so, the wind farm group is controlled using the reactive voltage control mode to prevent and control the fault ride-through action under large and rapid fluctuations in wind power output, including:

[0057] Calculating SVG dynamic reactive power margin The wind farm group is controlled in the reactive voltage control mode, and the SVG dynamic reactive margin is adjusted according to the SVG dynamic reactive margin. Update the SVG reactive upper limit, and based on the updated SVG reactive upper limit, perform wind farm group output according to a fixed control cycle under the reactive voltage control model. The steady-state reactive voltage control model is modeled and solved, and the reactive output values ​​of wind turbines and SVGs obtained are regularly sent to wind farms. The dynamic reactive reserve reserved by SVG is used to prevent and control fault ride-through actions under large and rapid fluctuations in wind power output.

[0058] Optionally, based on the simulation analysis results, determine whether the wind turbines in the wind farm group have experienced fault ride-through action. If not, set the SVG dynamic reactive margin to =0, the wind farm group is controlled by the fixed-cycle steady-state reactive voltage control of the wind farm group, and the dynamic reactive margin is set according to the SVG being 0. Update the SVG reactive upper limit, and based on the updated SVG reactive upper limit, perform wind farm group output according to a fixed control cycle under the reactive voltage control model. The steady-state reactive power and voltage control model is modeled and solved, and the reactive power output values ​​of wind turbines and SVGs obtained by the solution are regularly sent to the wind farm.

[0059] In yet another aspect, the present invention further provides a computing device comprising: one or more processors;

[0060] a processor for executing one or more programs;

[0061] When the one or more programs are executed by the one or more processors, the above-described method is implemented.

[0062] In another aspect, the present invention further provides a computer-readable storage medium having a computer program stored thereon, wherein when the computer program is executed, the method described above is implemented.

[0063] Compared with the prior art, the present invention has the following beneficial effects:

[0064] The present invention provides a wind farm reactive voltage control method for preventing and controlling fault ride-through under conditions of large and rapid fluctuations in wind power output. The method comprises: establishing a grid-connected model for a wind farm group, generating a data file for simulation calculation based on the grid-connected model; establishing a reactive voltage control mode that coordinates fixed-period steady-state reactive voltage control for the wind farm group with constant voltage response control at the SVG device level for the wind farm group; dynamically simulating the rapid and large fluctuations in the wind farm group's output based on the data file, and obtaining simulation analysis results that dynamically impact the voltage at the wind power grid connection point and at the wind turbine terminal; determining, based on the simulation analysis results, whether wind turbines in the wind farm group are experiencing fault ride-through; and if so, controlling the wind farm group using the reactive voltage control mode to prevent and control fault ride-through under conditions of large and rapid fluctuations in wind power output. The present invention standardizes the operation of reactive equipment such as multiple SVGs and wind turbines in a wind farm, optimizes reactive voltage control for wind farm groups under conditions of gradually increasing grid-connected capacity and low short-circuit ratios, promotes the adoption of new energy, and enhances grid security. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] Figure 1 is a flow chart of the method of the present invention;

[0066] Figure 2 is a flow chart of an embodiment of the method of the present invention;

[0067] Figure 3 This is a simulation curve diagram of a wind farm output that changes rapidly and significantly according to an embodiment of the method of the present invention;

[0068] Figure 4 A typical model structure diagram of a wind turbine generator system according to an embodiment of the method of the present invention;

[0069] Figure 5 This is an envelope diagram of the low voltage ride through protection action of a wind turbine generator set according to an embodiment of the method of the present invention;

[0070] Figure 6 This is a typical model structure and parameter diagram of SVG constant voltage control in an embodiment of the method of the present invention;

[0071] Figure 7 The SVG dynamic reactive output simulation curve and ΔQ of the embodiment of the method of the present invention are shown in FIG. s d The computational graph of

[0072] Figure 8 A schematic diagram of the power flow distribution of a typical mode in which a wind farm group is connected to a power grid and a wind farm has a uniform output of 80% according to an embodiment of the method of the present invention;

[0073] Figure 9 This is a simulation curve diagram of the rapid and substantial increase in the output of the hlf wind farm according to the method embodiment of the present invention;

[0074] Figure 10 This is a simulation curve diagram of the terminal voltage of the wind turbine generator set in the DLF wind farm according to the method embodiment of the present invention;

[0075] Figure 11 A simulation curve diagram of the wind farm grid-connected bus voltage and the main grid bus voltage according to an embodiment of the method of the present invention;

[0076] Figure 12 This is a simulation curve diagram of the active power transmitted by the main grid 500kV transformer mld according to the embodiment of the method of the present invention;

[0077] Figure 13 This is a simulation curve diagram of dynamic reactive power output of a single SVG with a capacity of 23Mvar in an hlf wind farm according to an embodiment of the method of the present invention;

[0078] Figure 14 This is a schematic diagram of the distribution of wind power, SVG reactive output, wind turbine terminal, grid connection point voltage, and access power flow after the reactive voltage of the wind farm group is optimized according to the method embodiment of the present invention;

[0079] Figure 15 The wind farm group SVG of the embodiment of the method of the present invention reserves dynamic reactive power to cope with large and rapid changes in the output of the wind farm group. Taking hlf as an example, a simulation curve diagram of the rapid and large changes in the wind farm output is shown;

[0080] Figure 16 A schematic diagram showing simulation results of the voltages at the wind turbine terminals, grid-connected bus, and main grid bus of the wind farm group SVG under rapid and significant changes in wind farm group output, with dynamic reactive power reserved and a constant voltage response control strategy adopted for the method embodiment of the present invention;

[0081] Figure 17 Schematic diagram of the simulation of dynamic reactive power output of SVG of a wind farm group under the condition of a large and rapid change in the output of the wind farm group according to the method embodiment of the present invention;

[0082] Figure 18 It is a structural diagram of the system of the present invention. DETAILED DESCRIPTION

[0083] Exemplary embodiments of the present invention will now be described with reference to the accompanying drawings. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein. These embodiments are provided to provide a thorough and complete disclosure of the present invention and to fully convey the scope of the present invention to those skilled in the art. The terminology used in the exemplary embodiments shown in the accompanying drawings is not intended to limit the present invention. In the accompanying drawings, identical elements are denoted by the same reference numerals.

[0084] Unless otherwise specified, the terms used herein (including technical terms) have the meanings commonly understood by those skilled in the art. In addition, it is understood that terms defined in commonly used dictionaries should be understood to have the same meanings as those in the context of the relevant fields, and should not be understood as idealized or overly formal meanings.

[0085] Example 1:

[0086] The present invention proposes a method for preventing and controlling fault ride-through actions under large and rapid fluctuations in wind power output, such as Figure 1 Shown, including:

[0087] Step 1: Establish a grid-connected model for a wind farm group, and generate a data file for simulation calculation based on the grid-connected model;

[0088] Step 2: Establish a reactive voltage control mode that coordinates the wind farm group's fixed-cycle steady-state reactive voltage control with the wind farm group's SVG equipment-level constant voltage response control;

[0089] Step 3: Dynamically simulate the rapid and large-scale change characteristics of the wind farm group output according to the data file, and obtain simulation analysis results of the dynamic impact on the wind power grid connection point and the wind turbine terminal voltage;

[0090] Step 4: Determine whether the wind turbines in the wind farm group have experienced fault ride-through based on the simulation analysis results. If so, control the wind farm group using the reactive voltage control mode to prevent and control fault ride-through under large and rapid fluctuations in wind power output.

[0091] Among them, establishing a wind farm group access grid model includes: establishing steady-state and transient equivalent aggregation models of wind farms, and establishing steady-state models and transient models of wind farm group access to the main grid based on the steady-state and transient equivalent aggregation models of wind farms.

[0092] The method includes establishing a steady-state and transient equivalent aggregation model of the wind farm, and establishing a steady-state model and a transient model of the wind farm group connected to the main grid based on the steady-state and transient equivalent aggregation model of the wind farm. The method includes:

[0093] Based on the wind conditions, turbine types, and internal wiring forms within the wind farm, multiple wind turbines within the wind farm are aggregated to generate equivalent aggregate models of the wind farm in steady and transient states.

[0094] Based on the steady-state and transient equivalent aggregation models of the wind farm, the wind power unit transformer, internal cables, grid-connected step-up transformer, supporting SVG and grid-connected lines are modeled. The main grid with a close electrical distance to the wind farm is modeled in detail, and the remaining main grids are modeled in an equivalent simplified manner to generate a steady-state model and a transient model of the wind farm group connected to the main grid.

[0095] Among them, the reactive voltage control mode includes: reserving the dynamic reactive margin of the wind farm group SVG, and using the wind farm group SVG equipment-level constant voltage response control to track voltage changes, automatically adjusting the reserved dynamic reactive margin of the wind farm group SVG to prevent and control fault ride-through actions, and performing fixed-cycle steady-state reactive voltage control of the wind farm group based on the remaining SVG capacity after reserving the dynamic reactive margin of the wind farm group SVG and the reactive output of the wind turbines.

[0096] According to the data file, a dynamic simulation of the rapid and large-scale change characteristics of the wind farm group output is performed, including:

[0097] Determine the basic output of the wind farm group based on the data file Wind conditions and historical output of wind farm groups;

[0098] Based on the basic output of wind farm groups Based on the wind conditions and historical output of the wind farm group, the rapid and large changes in the output of the wind farm group are predicted;

[0099] Dynamically simulate the rapid and drastic changes in wind farm output.

[0100] The dynamic simulation results include: simulation curves of wind farm group output changes.

[0101] Among them, based on the dynamic simulation results, the simulation analysis results are obtained, including:

[0102] Based on the dynamic simulation results, according to the basic output of the wind farm group The simulation determines the rapid and large-scale change characteristics of the wind farm group output under the operating status, and the dynamic impact on the wind power grid connection point and the voltage fluctuation of the wind turbine terminal. Based on the dynamic impact, the simulation curves and event information of the wind turbine fault ride-through action and the impact on the safety and stability of the power grid are determined.

[0103] The operating status includes reactive voltage and active phase angle.

[0104] Among them, the simulation determines the rapid and large-scale change characteristics of the wind farm group output, and the dynamic impact of the voltage fluctuation changes at the wind power grid connection point and the wind turbine terminal, while the wind turbine and SVG maintain the initial reactive power value unchanged.

[0105] The method further includes: establishing a high / low voltage fault ride-through control and protection model for wind turbines;

[0106] The typical envelope corresponding to the high / low voltage fault ride-through protection function of the wind turbine is discretized, and the action voltage threshold and duration are given for each discrete point. Multiple discrete points and the corresponding action voltage thresholds and durations are then entered into the high / low voltage fault ride-through protection model of the wind turbine.

[0107] Simulation is performed using the high / low voltage fault ride-through control and protection model of wind turbines.

[0108] Among them, the simulation curves include: wind turbine terminal voltage simulation curve, wind turbine active power and reactive power simulation curve, grid connection point bus voltage simulation curve and grid connection line active power and reactive power simulation curve.

[0109] The event information includes: event information of high / low voltage fault ride-through control and protection action of the wind turbine.

[0110] According to the simulation analysis results, it is determined whether the wind turbines in the wind farm group have experienced fault ride-through. If so, the wind farm group is controlled using the reactive voltage control mode to prevent and control the fault ride-through under large and rapid fluctuations in wind power output, including:

[0111] Calculating SVG dynamic reactive power margin The wind farm group is controlled in the reactive voltage control mode, and the SVG dynamic reactive margin is adjusted according to the SVG dynamic reactive margin. Update the SVG reactive upper limit, and based on the updated SVG reactive upper limit, perform wind farm group output according to a fixed control cycle under the reactive voltage control model. The steady-state reactive voltage control model is modeled and solved, and the reactive output values ​​of wind turbines and SVGs obtained are regularly sent to wind farms. The dynamic reactive reserve reserved by SVG is used to prevent and control fault ride-through actions under large and rapid fluctuations in wind power output.

[0112] Among them, according to the simulation analysis results, determine whether the wind turbines in the wind farm group have fault ride-through action. If not, set the SVG dynamic reactive margin to =0, the wind farm group is controlled by the fixed-cycle steady-state reactive voltage control of the wind farm group, and the dynamic reactive margin is set according to the SVG being 0. Update the SVG reactive upper limit, and based on the updated SVG reactive upper limit, perform wind farm group output according to a fixed control cycle under the reactive voltage control model. The steady-state reactive power and voltage control model is modeled and solved, and the reactive power output values ​​of wind turbines and SVGs obtained by the solution are regularly sent to the wind farm.

[0113] The present invention will be further described below with reference to specific implementation cases:

[0114] Specific implementation case process is as follows Figure 2 Shown, including:

[0115] (1) Based on power system simulation programs such as PSD, steady-state and dynamic (transient) models of wind farm groups connected to the main grid are established, and data files for simulation calculations are generated respectively.

[0116] (2) Establish a reactive voltage control mode that coordinates the fixed-period steady-state reactive voltage control of the wind farm group and the fixed voltage response control of the wind farm SVG equipment level to prevent and control the fault ride-through action under the rapid and large changes in the output of the weak power grid wind farm group.

[0117] (3) Based on the basic output of wind farm groups According to the wind conditions and historical output of the wind farm group, the rapid and large-scale change characteristics of the wind farm group output are predicted, and the PSD simulation program is used to dynamically simulate the rapid and large-scale change characteristics of the wind farm group output.

[0118] (4) Using PSD simulation program, based on the basic output of wind farm group Under the reactive voltage, active phase angle and other operating conditions, the wind turbine and SVG maintain the initial reactive value unchanged. The simulation analyzes the dynamic impact of the rapid and substantial changes in the output of the wind farm group on the voltage fluctuation changes at the wind power grid connection point and the wind turbine terminal, and evaluates the fault ride-through action of the wind turbine and its impact on the safety and stability of the power grid.

[0119] (5) Analyze the simulation results. If there is no wind turbine fault ride-through action, set the SVG dynamic reactive power margin to =0, and jump to step (6) to perform steady-state reactive voltage control of the wind farm group at a fixed period; if a wind turbine fault ride-through action occurs and affects the stable operation of the power grid, perform SVG dynamic reactive margin , and jump to step (6) to perform reactive voltage control that coordinates the steady-state reactive voltage control of the wind farm group with the constant period and the constant voltage response control of the wind farm SVG equipment level.

[0120] (6) Update SVG reactive power limit, in is the maximum capacitive reactive power determined according to the rated capacity of SVG, and jumps to step (7).

[0121] (7) According to the fixed control cycle, the wind farm group output The steady-state reactive voltage control model under the proposed scheme is modeled and solved, and the reactive output values ​​of wind turbines and SVG obtained by the solution are regularly sent to the wind farm. The dynamic reactive reserve reserved by SVG can meet the prevention and control of fault ride-through actions under large and rapid fluctuations in wind power output.

[0122] Preferably, the step (1):

[0123] The wind farm adopts an equivalent aggregation model, and aggregates multiple wind turbines in the field according to the wind conditions, unit types, internal wiring, etc. of the wind farm. For a typical 300MW wind farm with a total of 48 wind turbines with a single unit capacity of 6.25MW, it is generally aggregated into 2-4 equivalent wind turbines, and the equivalent wind turbine capacity is a multiple of a single wind turbine. The dynamic (transient) model of the aggregated wind turbine adopts the control model, structure and parameters of the typical wind turbine type; in addition to wind turbines, the wind farm access modeling also includes the modeling of wind power unit transformers, internal cables, grid-connected boost transformers, supporting SVGs and grid-connected lines; according to the influence range of the wind farm group's aggregation, access and external transmission, the main grid is modeled in detail or simplified. Generally, the regional power grid to which the wind farm group is connected requires detailed modeling, and the main grid outside the regional power grid can be modeled in an equivalent simplified manner according to the situation.

[0124] Preferably, the step (2):

[0125] The reactive voltage control mode that coordinates the fixed-period steady-state reactive voltage control of the wind farm group with the constant voltage response control of the SVG equipment level in the wind farm is further explained. That is, when the reactive power of the SVG in the wind farm is sufficient, the constant voltage response control at the SVG equipment level is adopted to track the voltage fluctuation caused by the large and rapid changes in wind power output, automatically adjust the reactive power output, maintain the voltage at the wind farm grid connection point and the terminal within a given range, and deal with the fault ride-through problem that may arise from voltage fluctuations; after reserving the dynamic reactive capacity of the SVG to deal with fault ride-through, the SVG with the remaining reactive capacity is taken into account, and coordinated with the reactive output of multiple wind turbines in the wind farm, a steady-state reactive voltage optimization control model under a fixed control period is established, and the wind power voltage amplitude and fluctuation under the predictable output changes of the wind farm group are controlled within a given target value or target range. At the same time, multiple objectives such as minimizing the reactive power control amount and balancing the reactive power control amount among multiple wind turbines in the wind farm and among multiple sets of SVG are achieved.

[0126] Preferably, the step (3):

[0127] The simulation is based on the PSD power system dynamic simulation program. The renewable energy power generation output IGV model in the program can simulate the large and rapid changes in wind power output. The continuous change curve of wind power output is discretized into several moments and the wind power size at the corresponding moments, and these multiple discrete power points and discrete moments that represent the change in wind power output are filled into the IGV model. By running the PSD program, a simulation curve of the wind farm output change can be obtained. The output of a wind farm with a simulated installed capacity of 200MW increases rapidly and significantly from 170MW at 1s to a maximum of 200MW at 5s. The simulation curve is as follows Figure 3 As shown:

[0128] Preferably, the step (4):

[0129] The wind turbine high / low voltage fault ride-through control and protection model is established based on the PSD program. The wind turbine dynamic model containing multiple control function modules is established based on the PSD program. The structure of the wind turbine dynamic model is as follows Figure 4 As shown in the figure, the wind turbine fault ride-through control related models are: WEV, WLP, and WLQ.

[0130] WDF, WFC models - double-fed, direct-drive generator models;

[0131] WES model - converter current control and limiting model;

[0132] WEV model - fault ride-through state judgment model;

[0133] WLP model - active power control model under fault ride-through state;

[0134] WLQ model - reactive power control model under fault ride-through state;

[0135] WME model - axis model;

[0136] WTG model - wind power model;

[0137] WGF model - pitch angle control model;

[0138] WEP model - active power control model under normal operating conditions;

[0139] WEQ model - reactive power control model under normal operating conditions.

[0140] Based on the PSD program, a high / low voltage fault ride-through protection model RE for wind turbines is established. The main parameters of the RE model are the voltage threshold inverse time envelope setting values ​​of the high and low voltage protection actions. The low voltage fault ride-through protection function of the wind turbine of the present invention has a typical envelope as shown in FIG. Figure 5 As shown:

[0141] The envelope is discretized, and the action voltage threshold and duration are given for each discretized point. Multiple discrete points are filled into the RE model.

[0142] Run the PSD dynamic simulation program and output the following simulation curves of key physical quantities and key event information:

[0143] Wind turbine terminal voltage simulation curve;

[0144] Wind turbine active power and reactive power simulation curves;

[0145] Simulation curve of bus voltage at the grid connection point;

[0146] Active power and reactive power simulation curves of grid-connected lines;

[0147] Event information of high / low voltage fault ride-through control and protection action of wind turbines.

[0148] Based on the simulation curve and event information, it is determined whether the high and low voltage fault ride-through protection of the wind turbine is activated, whether the turbine is tripped, and the impact on the safety and stability of the power grid is evaluated.

[0149] Preferably, the step (5):

[0150] In case of wind turbine fault ride-through and affecting the stable operation of the power grid, SVG dynamic reactive margin is used. The calculation is as follows:

[0151] Based on wind farm group output The wind farm SVG is set as the basic operating state, and the response control strategy of the target bus voltage (usually the grid connection point) is set. The upper and lower limits of the SVG reactive power are set to a custom larger value (the set limit will not cause the SVG output reactive power to reach the upper limit). Based on the PSD dynamic simulation analysis program, the reactive output increment of the SVG is simulated and analyzed to maintain the target bus voltage constant and ensure that the wind turbine does not trigger the fault ride-through action when the wind farm group output changes rapidly and significantly. This increment is The additional value is the dynamic reactive power margin reserved for SVG. The key strategies and parameter settings are as follows:

[0152] The dynamic simulation models VG and VG+ of the wind farm SVG are established based on the PSD program. The control strategy adopted by the SVG is a responsive control strategy that sets the target bus voltage to a given value. This strategy simulates the dynamic function of automatically adjusting the reactive output within the upper and lower limits of the SVG reactive power to maintain the target bus voltage at a given value when voltage fluctuations are caused by rapid changes in wind power output.

[0153] The SVG model structure is as follows Figure 6 The specific parameters are as follows:

[0154] BNAME, the name of the node connected to the system;

[0155] BASE, the reference voltage of the node connected to the system (kV);

[0156] MVABASE, rated capacity (MVA);

[0157] T 1V , time constant of constant voltage control filter and measurement circuit (seconds);

[0158] T 2V, constant voltage control first stage leading time constant (seconds);

[0159] T 3V , constant voltage control first stage hysteresis time constant (seconds);

[0160] T 4V , constant voltage control second stage advance time constant (seconds);

[0161] T 5V , constant voltage control second stage hysteresis time constant (seconds);

[0162] T PV , time constant of constant voltage control proportional link (seconds);

[0163] T SV , constant voltage control STATCOM response delay (seconds);

[0164] K PV , constant voltage control proportional link amplification factor;

[0165] K IV , the amplification factor of the constant voltage control integral link;

[0166] K D , the slope of the SVG's VI characteristic curve must be greater than or equal to 0;

[0167] REF_BNAME, control node name;

[0168] BASE, control node reference voltage;

[0169] V MAX , the upper limit of the voltage limiting link (pu);

[0170] V MIN , the lower limit of the voltage limiting link (pu);

[0171] I CMAX , maximum capacitive current (pu, based on SVG rated capacity);

[0172] I LMAX , maximum inductive current (pu, based on SVG rated capacity);

[0173] SVG control mode, distinguished by flags 0 and 1, 0-constant voltage control, 1-constant reactive power control.

[0174] Set the rated capacity parameter MVABASE (the upper and lower limits of reactive power output) in the SVG model to a large value; and set the initial value of SVG to Under the given set voltage of SVG control bus, the PSD dynamic simulation program is used to simulate the dynamic reactive output curve of SVG in order to maintain the control bus voltage constant under the rapid and large changes of wind power output. The maximum value of SVG dynamic reactive output is compared with the initial reactive value of SVG. Subtract and get the dynamic reactive power increment of SVG It is used as the dynamic reactive power margin reserved by SVG to cope with the rapid and large changes in wind power output. Typical SVG dynamic reactive power output simulation curve and The request is as follows Figure 7 As shown:

[0175] Preferably, the step (7):

[0176] The steady-state reactive voltage optimization control of regional wind farm groups is based on the principle of priority action of SVG in each wind farm, with the grid connection point voltage as a given value, the minimum reactive power control amount in the field, the balanced distribution of reactive power control amount among multiple wind turbines in the field, and the balanced distribution among multiple SVGs as optimization objectives, and the dynamic reactive power margin of SVG in step (5) is considered. The reservation is used to take into account the goal of preventing and controlling fault crossing.

[0177] Define the reactive margin M of the i-th wind turbine and SVG or other reactive equipment in a wind farm w,i 、M s,i :

[0178]

[0179]

[0180] Where: Q i 、 are the reactive current value, reactive upper limit, and reactive lower limit of the i-th device respectively; ΔQ i is the optimization variable, representing the amount of reactive power regulation of the equipment; the subscript w represents the wind turbine, and the subscript s represents the SVG. According to the grid connection guidelines, the upper and lower limits of the reactive power of the i-th wind turbine in the wind farm should meet the requirements of dynamically adjusting the power factor within the range of 0.95 leading to 0.95 lagging at rated active power output, that is: The reactive power lower limit vector of multiple SVGs in a wind farm is generally determined according to the rated capacity, that is: The SVG reactive upper limit vector is determined by deducting the dynamic reactive margin reserved for large and rapid changes in wind power output from the rated capacity, that is:

[0181] Define the average reactive power margin of wind turbines and reactive equipment such as SVG in a wind farm

[0182]

[0183]

[0184] Where: Z is the wind turbine or SVG equipment set, where Z w For wind turbines, Z s is SVG, i is the i-th wind turbine or SVG device.

[0185] The objective function of steady-state reactive power and voltage control of wind farm group is as follows:

[0186]

[0187] Satisfy the following constraints:

[0188] G(ΔQ)≤0

[0189] The constraints are expanded as follows:

[0190]

[0191]

[0192] Q min ≤Q+ΔQ≤Q max (8)

[0193] Where V w 、 and are the current value, lower limit and upper limit vectors of the bus voltage at the wind turbine terminal of each wind farm; V c 、 and are the current value, lower limit and upper limit vectors of the voltage of the control busbar (generally the grid connection point) of each wind farm; Q, Q min and Q max are the current reactive value, reactive lower limit and upper limit vectors of reactive equipment such as wind turbines and SVG in each wind farm; ΔQ is the regulation quantity vector of reactive equipment; The sensitivity matrices of the voltage at the grid connection point of each wind farm and the voltage at the wind turbine terminal of each wind farm to the reactive output of the reactive equipment (SVG, wind turbine) of each wind farm; The voltage optimization setting value of each wind farm control bus (generally the grid connection point) is generally given by the previous level AVC. The optimization target is a multi-objective function, and the following multiple targets are achieved through wind farm reactive voltage control: 1) The wind farm control bus voltage is the setting value, corresponding to the first item in objective function (5); 2) The reactive power adjustment of wind turbines and SVGs in the wind farm is minimized, corresponding to the second and third items in objective function (5); 3) The reactive power adjustment of wind turbines in the wind farm is evenly distributed among multiple wind turbines, and the reactive power adjustment of SVGs is evenly distributed among multiple SVGs, corresponding to the fourth item in objective function (5). W c 、W qw 、W qs and W m are the weights of each sub-objective function respectively. Since the wind farm SVG has the characteristics of a small number of units, only outputting reactive power and fast action speed, from the perspective of meeting the voltage control timeliness under rapid and large wind power changes, and the response action of the power electronic equipment with a small number of units can reduce the risk of control oscillation, broadband oscillation, etc., and considering the advantages of SVG only outputting reactive power such as control decoupling, this patent selects SVG to take precedence over wind turbines in steady-state reactive voltage regulation after reserving SVG dynamic reactive power, and realizes the action priority by setting the weights of the wind turbine and SVG adjustment amount of the objective function (5), that is: W qs The weight is much smaller than W qw .

[0194] The present invention adopts the sequential linear programming method (SLP) to solve the control models (5) to (8), linearizes the above nonlinear optimization problem multiple times, and solves it based on the linear programming method, that is, adopts the SLP method to obtain the control solution ΔQ.

[0195] The main effects of the present invention are as follows:

[0196] 1) A wind farm reactive voltage control model and control mode with multiple objectives and multiple constraints, such as integrated steady-state and dynamic (transient) reactive voltage, was established: The proposed wind farm reactive voltage control model can be used to assess the high / low voltage fault ride-through risk of wind power with large and rapid changes in wind farm group output under weak power grid. In response to the possible fault ride-through problem, a reactive voltage control mode that coordinates the wind farm group fixed-cycle steady-state reactive voltage control with the wind farm SVG equipment-level constant voltage response control is proposed, giving full play to the advantages of SVG such as fast action speed, small number of sets in the field, and only output of reactive power. Advantages include using SVG to reserve dynamic reactive margin and implementing a constant voltage response control strategy to prevent and control fault ride-through. After considering the SVG's reserved dynamic reactive capacity, a fixed-period steady-state reactive voltage optimization control is then performed, coordinating the remaining SVG capacity with multiple reactive devices, such as wind turbines. Steady-state reactive voltage control also prioritizes SVG operation, and then coordinates the reactive output of multiple wind turbines to achieve multi-objective steady-state reactive voltage optimization, including maintaining a given grid connection point voltage, minimizing reactive control, and balancing device control. In the proposed control mode, a smaller number of power electronic devices, SVG, prioritize operation over a larger number of power electronic devices, such as wind turbines, further mitigating dynamic (transient) risks such as switching control oscillations and broadband oscillations. Combining these multiple aspects, a more rational steady-state and dynamic (transient) reactive voltage optimization coordination is achieved through reactive voltage modeling and control mode formulation.

[0197] 2) A method for calculating the dynamic reactive power reserve of the SVG is proposed, enabling a decomposition and coordination of steady-state reactive power and voltage control and dynamic reactive power and voltage control for fault ride-through prevention and control. First, the SVG constant voltage response control strategy is simulated using a PSD dynamic program, and the dynamic reactive power that should be reserved for fault ride-through prevention and control to prevent unexpected large and rapid changes in wind power output is quantified. Then, taking into account the SVG after a portion of the reactive power is reserved, the reactive power output of the wind farm group turbines and the SVG is coordinated and optimized under a fixed control cycle, achieving a decomposition and coordination of steady-state and dynamic (transient) reactive power and voltage control. Furthermore, the dynamic response of the SVG is simulated using a power system dynamic simulation program, enabling a more accurate calculation of the SVG's dynamic reactive power reserve.

[0198] 3) A method of integrating dynamic simulation of reactive voltage into steady-state reactive voltage control modeling is proposed, which can more accurately simulate dynamic characteristics such as wind power fault ride-through and SVG response control: the dynamic simulation of reactive voltage is coordinated and integrated into the steady-state reactive voltage control modeling and solution, and the fault ride-through action risk of wind farms under weak power grids is simulated and evaluated, and the dynamic reactive output characteristics under the SVG response control strategy are simulated. Combined with the steady-state reactive voltage control, the credibility and availability of the reactive voltage control strategy and control results are increased.

[0199] The present invention takes into account multiple objectives such as dynamic (transient) and steady-state reactive voltage, and models the coordinated control of reactive voltage of multiple devices in a wind farm group. Taking into account the characteristics of different reactive devices in the field, a coordinated control mode is formulated, and a model solving method is given. The action of reactive equipment such as multiple SVGs and multiple wind turbines in a wind farm is standardized, and the reactive voltage control of a wind farm group is optimized under gradually increasing grid-connected capacity and low short-circuit ratio, which promotes the acceptance of new energy and improves the security of the power grid.

[0200] The following takes the connection of a wind farm group to the power grid as an example to further describe the specific implementation methods of the present invention in detail.

[0201] The schematic diagram of the grid structure of wind farm group connected to the power grid is as follows: Figure 8 As shown, the installed capacity of MQF and HNF wind farms is 200MW respectively, and the installed capacity of HLF and DLF wind farms is 300MW respectively. The total installed capacity of this wind farm group is 1000MW; the capacity of a single wind turbine is 6.25MW, so there are 32 wind turbines in the 200MW wind farm and 48 wind turbines in the 300MW wind farm. The wind turbines in each wind farm are boosted to 35kV through unit transformers. The 35kV medium-voltage cables are then connected to the 35 / 220kV booster stations MQ, HN, HL, and DL in each wind farm, where they are boosted to 220kV and connected to the grid. The MQF and HNF wind farms are each equipped with two SVGs, each with a capacity of 18Mvar, on the 35kV side of their respective booster transformers MQ and HN. The total SVG capacity for each farm is 36Mvar, with the upper and lower limits of the SVG reactive capacity being 36Mvar and -36Mvar, respectively. The HLF and DLF wind farms are each equipped with two SVGs, each with a capacity of 23Mvar, on the 35kV side of their respective booster transformers HL and DL. The total SVG capacity for each farm is 46Mvar, with the upper and lower limits of the SVG reactive capacity being 46Mvar and -46Mvar, respectively. The wind farm's upper and lower reactive power limits are dynamically adjustable within a range of 0.95 leading to 0.95 lagging based on the wind farm's rated active power factor. For example, the upper and lower reactive power limits for MQF and HNF wind farms are 66 Mvar and -66 Mvar, respectively; for HLF and DLF wind farms, they are 99 Mvar and -99 Mvar, respectively. After a portion of the installed wind power is consumed by local loads, the remaining power is transmitted through a 500 kV substation (MLD). The regional power grid to which the wind farm cluster is connected has no direct connection to conventional power sources such as thermal power plants, and only has a 1000 MW wind farm cluster.

[0202] Based on the typical access mode of wind farm groups, the research is conducted. The active and reactive power flow of the power grid and the node voltage are shown in the figure below: (1) The active power flow is as follows. The wind farms in the 1000MW wind farm group are evenly outputting 80% of the installed capacity. Specifically, the mqf wind farm is 160MW, the hlf wind farm is 240MW, the dlf wind farm is 240MW, and the hnf wind farm is 160MW. The wind power output of the wind farm group is relatively large, totaling 800MW. After a part of the local 220kV load is consumed, the remaining wind power of about 416MW is sent to the 500kV substation mld. The 220kV power stations with larger load power are: ml station is 70MW, arq station is 99.8MW, ay station is 37.8MW, tjb station is 15MW, hzx station is 89.3MW, and mgq station is 31.5MW. (2) The reactive voltage situation is as follows: The reactive output of the wind turbines at the four wind farms mqf, hlf, dlf, and hnf is 0. The reactive output of the SVGs connected to the low-voltage side of the 220kV wind farm booster stations mq, hl, dl, and hn are 24Mvar, 26Mvar, 26Mvar, and 22Mvar, respectively. The upper-level AVC controls the bus voltage at the wind farm grid connection point within a range of 230 to 232kV, with mq at 230.3kV, hl at 231.7kV, dl at 231.8kV, and hn at 230.4kV.

[0203] The specific implementation includes the following steps:

[0204] Based on the grid structure and arrangement of the above-mentioned wind farm group access to the power grid, steady-state and dynamic (transient) modeling of the wind farm group access is carried out to form the data files required for calculation and analysis.

[0205] Based on the maximum basic output of 800MW of the wind farm group, the PSD power system dynamic program is used to simulate the rapid increase of wind power output. The output of the farm group increases rapidly to the full output of 1000MW. Among them, the output of the MQF and HNF wind farms increases rapidly from the initial 160MW to the full output of 200MW; the output of the HLF and DLF wind farms increases rapidly from the initial 240MW to the full output of 300MW. Taking the HLF wind farm as an example, the simulation curve diagram is given as follows Figure 9 As shown:

[0206] Based on the rapid growth of the wind farm cluster's base output to 800MW, the initial reactive power of the wind turbines at each wind farm was 0Mvar. The initial reactive power of the SVGs at the MQF, HLF, DLF, and HNF wind farms was 24Mvar, 26Mvar, 26Mvar, and 22Mvar, respectively. During this period of wind power output growth, the reactive power of the wind turbines and SVGs remained constant at their initial values. A PSD dynamic simulation program was used to assess the risk of wind turbine fault ride-through caused by the rapid and substantial increase in wind power output. Simulation analysis revealed that during this period of rapid wind power output growth, the voltages at the grid connection points and wind turbines at each wind farm continued to drop due to the lack of timely dynamic reactive power support provided by the wind farms. This triggered the dynamic control of wind turbine fault ride-through, causing the wind turbines to frequently enter and exit low-voltage fault ride-through, resulting in unreliable operation of the wind turbines. Furthermore, the main grid bus voltage and active power flow experienced oscillations, impacting the stable operation of the power grid. Taking the DLF wind farm as an example, the simulation curves of the wind turbine terminal voltage, grid-connected bus voltage, main grid 500kV station MLD bus voltage, and active power passing through the MLD station are output as follows Figure 10 、 11 and 12;

[0207] A reactive voltage control mode that coordinates station-level fixed-cycle reactive voltage optimization control with SVG equipment-level constant voltage response control is established to prevent and control fault ride-through actions under rapid and significant changes in the output of weak grid wind farm groups. The key to the SVG constant voltage response control strategy is to calculate the dynamic reactive power margin required to prevent and control fault ride-through actions. The PSD dynamic simulation program is used for calculation. The SVG of each wind farm is set to a constant voltage response control strategy (the control bus is the wind farm grid bus), and the upper and lower limits of the SVG reactive power are given a larger value (to ensure that the actual SVG output reactive power will not reach the limit). The simulation simulates the rapid and substantial increase in the output of the wind farm group. In order to maintain the grid bus voltage at a given value, the maximum reactive power output of each wind farm SVG is calculated, and the difference is made with the initial reactive power of the SVC to obtain the dynamic reactive power margin that should be reserved. Taking the hlf wind farm as an example, the dynamic reactive output simulation curve of a single SVG with a rated capacity of 23Mvar is as follows: Figure 13 As shown:

[0208] The hlf wind farm has a single 23Mvar SVG with an initial output of 13Mvar and a maximum dynamic reactive output of 27.8Mvar. Therefore, the dynamic reactive margin required for the SVG to prevent and control fault ride-through is 14.8Mvar. The total dynamic reactive margin reserved for the two SVGs at the hlf wind farm is 29.6Mvar, which can be calculated as 30Mvar. Calculations show that the total dynamic reactive margin reserved for the two SVGs at the dlf, mqf, and hnf wind farms is 30Mvar, 23Mvar, and 30Mvar, respectively.

[0209] Through the following formula Update SVG reactive caps where is the wind farm SVG rated capacity, Reserve dynamic reactive power margin for wind farm SVG. The rated capacities of SVG for hlf, dlf, mqf, and hnf wind farms are 46Mvar, 46Mvar, 36Mvar, and 36Mvar respectively. The dynamic reactive power margin reserved for SVG for each wind farm is 30Mvar, 30Mvar, 23Mvar, and 30Mvar respectively. Therefore, the dynamic reactive power margin of SVG for hlf, dlf, mqf, and hnf wind farms is 46Mvar, 46Mvar, 36Mvar, and 36Mvar respectively. They are 16Mvar, 16Mvar, 13Mvar and 6Mvar respectively. There are two SVGs in each wind farm. Therefore, the power of a single SVG is They are 8Mvar, 8Mvar, 6Mvar (6.5Mvar rounded up), and 3Mvar respectively. Let the upper and lower limits of the capacity of a single SVG in each wind farm hlf, dlf, mqf, and hnf be -23Mavr~8Mvar, -23Mvar~8Mvar, -18Mvar~6Mvar, and -18Mvar~3Mvar respectively; the upper and lower limits of the total reactive power of each wind farm are -99Mavr~99Mvar, -99Mavr~99Mvar, -66Mvar~66Mvar, and -66Mvar~66Mvar respectively; the upper and lower limits of the reactive power of a single wind turbine in each wind farm are -2.06Mvar~2.06Mvar (total reactive power of the wind farm / number of wind turbines). According to the fixed control cycle, the wind farm group output is carried out. Modeling and solving of steady-state reactive power and voltage control model under . and The upper and lower limits of the wind turbine terminal voltage are 0.97pu and 1.07pu respectively; and The upper and lower limits of the grid connection point voltage are also 0.97pu and 1.07pu respectively. w , grid-connected bus voltage V c They are respectively Figure 8The corresponding bus voltage amplitudes in the "Schematic diagram of power flow distribution for a typical wind farm cluster connected to the grid and with 80% uniform output" are shown. Under these modes, the total reactive output of the wind turbines in each wind farm hlf, dlf, mqf, and hnf is 0 Mvar, and the total reactive output of the SVG is 26 Mvar (13 Mvar per unit), 26 Mvar (13 Mvar per unit), 24 Mvar (12 Mvar per unit), and 22 Mvar (11 Mvar per unit), respectively. The sensitivity of the wind farm grid connection point voltage and wind turbine terminal voltage to the wind turbine reactive power and wind farm SVG reactive power under this mode is calculated, and the results are shown in Table 1.

[0210] Table 1

[0211] <![CDATA[Sensitivity S vq > <![CDATA[△Q w,hlf ]]> <![CDATA[△Q w,dlf ]]> <![CDATA[△Q w,mqf ]]> <![CDATA[△Q w,hnf ]]> <![CDATA[△Q s,hlf ]]> <![CDATA[△Q s,dlf ]]> <![CDATA[△Q s,mqf ]]> <![CDATA[△Q s,hnf ]]> <![CDATA[△V c,hlf ]]> 0.1 0.08 0.08 0.06 0.1 0.08 0.08 0.06 <![CDATA[△V c,dlf ]]> 0.06 0.1 0.06 0.04 0.06 0.1 0.06 0.04 <![CDATA[△V c,mqf ]]> 0.06 0.06 0.12 0.06 0.06 0.06 0.12 0.06 <![CDATA[△V c,hnf ]]> 0.06 0.06 0.06 0.08 0.06 0.06 0.06 0.08 <![CDATA[△V w,hlf ]]> 0.22 0.06 0.06 0.06 0.18 0.06 0.06 0.06 <![CDATA[△V w,dlf ]]> 0.08 0.24 0.08 0.06 0.08 0.2 0.08 0.06 <![CDATA[△V w,mqf ]]> 0.08 0.08 0.32 0.06 0.08 0.08 0.26 0.06 <![CDATA[△V w,hnf ]]> 0.06 0.06 0.06 0.28 0.06 0.06 0.06 0.2

[0212] Substitute the following parameters into the reactive power and voltage optimization control models (1) to (8):

[0213] Wind turbine terminal voltage upper and lower limits Wind farm grid connection point voltage upper and lower limits Reactive power upper and lower limits Q of wind turbines and wind farm SVG min , Q max , the sensitivity of wind farm grid connection point and wind turbine terminal voltage to wind farm SVG and wind turbine reactive power etc.; Each wind farm control bus, i.e. the target setting range of the grid connection point voltage It is 230~232kV.

[0214] The multiple wind turbines in each wind farm are equivalent to two wind turbines through equivalent aggregation method, and the initial reactive power is Q w1 , Q w2 The number of SVGs in the wind farms remains the same, with two sets of SVGs in each wind farm. The initial reactive power is Q s1 , Q s2 The equivalent wind farm wind turbines and SVG reactive initial values ​​are shown in Table 2:

[0215] Table 2

[0216]

[0217]

[0218] The equivalent wind farm wind turbine terminal voltage and the initial values ​​of the wind farm grid connection point voltage are shown in Table 3:

[0219] Table 3

[0220]

[0221] In order to cope with the fault ride-through problem caused by the voltage fluctuation of wind power under the rapid and large changes in the output of wind farm groups, it has been calculated that the dynamic reactive margin reserved for the SVG of hlf, dlf, mqf, and hnf wind farms is 30Mvar, 30Mvar, 23Mvar, and 30Mvar respectively. Therefore, the Q of each wind farm SVG is s max They are 16Mvar, 16Mvar, 13Mvar, and 6Mvar respectively. The Q of a single SVG is s max The initial reactive power of a single SVG unit, 13 Mvar, 13 Mvar, 12 Mvar, and 11 Mvar, exceeded the maximum value of the SVG. Therefore, steady-state reactive power optimization of the wind farm cluster was required to re-optimize the reactive power distribution between the wind farm SVGs and wind turbines, while minimizing the change in the wind farm's reactive power adjustment. This ensured that the SVG reactive power was evenly distributed among all SVGs within the farm, and that the wind turbine reactive power was evenly distributed among all wind turbines within the farm. This ultimately achieved the goal of maintaining the voltage at the wind farm connection point within the set range of 230 to 232 kV.

[0222] The reactive power and voltage optimization models (1) to (8) are solved by using the sequential linear programming algorithm, and the reactive power adjustment ΔQ of each wind farm SVG and wind turbine is obtained as shown in Table 4:

[0223] Table 4

[0224]

[0225] The reactive power variation ΔQ of each wind farm SVG and wind turbine is superimposed on the initial reactive power to obtain the final optimized solution of the wind farm SVG and wind turbine reactive power, as shown in Table 5:

[0226] Table 5

[0227] wind farm <![CDATA[Q w1,hlf ]]> <![CDATA[Q w2,hlf ]]> <![CDATA[Q w1,dlf ]]> <![CDATA[Q w2,dlf ]]> <![CDATA[Q w1,mqf ]]> <![CDATA[Q w2,mqf ]]> <![CDATA[Q w1,hnf ]]> <![CDATA[Q w2,hnf ]]> Fan reactive power 5 5 5 5 6 6 8 8 wind farm <![CDATA[Q s1,hlf ]]> <![CDATA[Q s2,hlf ]]> <![CDATA[Q s1,dlf ]]> <![CDATA[Q s2,dlf ]]> <![CDATA[Q s1,mqf ]]> <![CDATA[Q s2,mqf ]]> <![CDATA[Q s1,hnf ]]> <![CDATA[Q s2,hnf ]]> SVG reactive 8 8 8 8 6 6 3 3

[0228] Among them, after the reactive voltage of the wind farm group is optimized, the wind farm wind power, SVG reactive output and wind turbine terminal, grid connection point voltage and access flow distribution are as follows: Figure 14 As shown in Figure 2, the wind farm group SVG reserves dynamic reactive power to cope with the rapid and large changes in the wind farm group output. Taking hlf as an example, the simulation curve of the rapid and large changes in the wind farm output is as follows: Figure 15 As shown in the figure, the SVG of the wind farm group reserves dynamic reactive power and adopts a constant voltage response control strategy. The simulation results of the voltages of the wind turbine terminals, grid-connected bus and main grid bus in the case of large and rapid changes in the output of the wind farm group are as follows: Figure 16As shown in the figure, the simulation results of the dynamic reactive power output of the wind farm group SVG under the rapid and large changes in the wind farm group output are as follows: Figure 17 shown.

[0229] From the above simulation result curve, we can see that the initial reactive power of a single SVG in the hlf and dlf wind farms gradually increases from 8Mvar to 22.5Mvar (each wind farm releases 29Mvar of the 30Mvar dynamic reactive power reserved by two SVGs), the initial reactive power of a single SVG in the mqf wind farm gradually increases from 6Mvar to 17.2Mvar (the wind farm releases 22.4Mvar of the 23Mvar dynamic reactive power reserved by two SVGs), and the initial reactive power of a single SVG in the hnf wind farm gradually increases from 3Mvar to 1. 8Mvar (the wind farm fully releases the 30Mvar dynamic reactive power reserved by the two SVGs). The wind farm group SVG's constant voltage response control tracks voltage changes and automatically outputs reactive power to maintain voltage fluctuations at the wind farm connection point and at the generator end under the rapid and substantial increase in wind farm group output. The above bus voltage simulation results show that when the wind farm has sufficient reactive power, the automatic output of the dynamic reactive power reserved by the SVG can smooth out voltage fluctuations under rapid and substantial changes in wind power output, maintaining the voltage within a relatively constant range and effectively preventing and controlling wind power fault ride-through.

[0230] Example 2:

[0231] The present invention also proposes a fault ride-through prevention and control system 200 under large and rapid fluctuations in wind power output, such as Figure 18 Shown, including:

[0232] Initialization unit 201 is used to establish a wind farm group access grid model, generate a data file for simulation calculation based on the access grid model; establish a reactive voltage control mode that coordinates the wind farm group's fixed-period steady-state reactive voltage control and the wind farm group's SVG device-level constant voltage response control;

[0233] The simulation unit 202 is used to dynamically simulate the rapid and large-scale change characteristics of the wind farm group output according to the data file, and obtain simulation analysis results of the dynamic impact on the wind power grid connection point and the wind turbine terminal voltage;

[0234] The control unit 203 is used to determine whether the wind turbines in the wind farm group have experienced fault ride-through according to the simulation analysis results. If so, the wind farm group is controlled in the reactive voltage control mode to prevent and control the fault ride-through under large and rapid fluctuations in wind power output.

[0235] Among them, establishing a wind farm group access grid model includes: establishing steady-state and transient equivalent aggregation models of wind farms, and establishing steady-state models and transient models of wind farm group access to the main grid based on the steady-state and transient equivalent aggregation models of wind farms.

[0236] The method includes establishing a steady-state and transient equivalent aggregation model of the wind farm, and establishing a steady-state model and a transient model of the wind farm group connected to the main grid based on the steady-state and transient equivalent aggregation model of the wind farm. The method includes:

[0237] Based on the wind conditions, turbine types, and internal wiring forms within the wind farm, multiple wind turbines within the wind farm are aggregated to generate equivalent aggregate models of the wind farm in steady and transient states.

[0238] Based on the steady-state and transient equivalent aggregation models of the wind farm, the wind power unit transformer, internal cables, grid-connected step-up transformer, supporting SVG and grid-connected lines are modeled. The main grid with a close electrical distance to the wind farm is modeled in detail, and the remaining main grids are modeled in an equivalent simplified manner to generate a steady-state model and a transient model of the wind farm group connected to the main grid.

[0239] Among them, the reactive voltage control mode includes: reserving the dynamic reactive margin of the wind farm group SVG, and using the wind farm group SVG equipment-level constant voltage response control to track voltage changes, automatically adjusting the reserved dynamic reactive margin of the wind farm group SVG to prevent and control fault ride-through actions, and performing fixed-cycle steady-state reactive voltage control of the wind farm group based on the remaining SVG capacity after reserving the dynamic reactive margin of the wind farm group SVG and the reactive output of the wind turbines.

[0240] According to the data file, a dynamic simulation of the rapid and large-scale change characteristics of the wind farm group output is performed, including:

[0241] Determine the basic output of the wind farm group based on the data file Wind conditions and historical output of wind farm groups;

[0242] Based on the basic output of wind farm groups Based on the wind conditions and historical output of the wind farm group, the rapid and large changes in the output of the wind farm group are predicted;

[0243] Dynamically simulate the rapid and drastic changes in wind farm output.

[0244] The dynamic simulation results include: simulation curves of wind farm group output changes.

[0245] Among them, based on the dynamic simulation results, the simulation analysis results are obtained, including:

[0246] Based on the dynamic simulation results, according to the basic output of the wind farm group The simulation determines the rapid and large-scale change characteristics of the wind farm group output under the operating status, and the dynamic impact on the wind power grid connection point and the voltage fluctuation of the wind turbine terminal. Based on the dynamic impact, the simulation curves and event information of the wind turbine fault ride-through action and the impact on the safety and stability of the power grid are determined.

[0247] The operating status includes reactive voltage and active phase angle.

[0248] Among them, the simulation determines the rapid and large-scale change characteristics of the wind farm group output, and the dynamic impact of the voltage fluctuation changes at the wind power grid connection point and the wind turbine terminal, while the wind turbine and SVG maintain the initial reactive power value unchanged.

[0249] Among them, based on the dynamic simulation results, obtaining simulation analysis results also includes: establishing a high / low voltage fault ride-through control and protection model for wind turbines;

[0250] The typical envelope corresponding to the high / low voltage fault ride-through protection function of the wind turbine is discretized, and the action voltage threshold and duration are given for each discrete point. Multiple discrete points and the corresponding action voltage thresholds and durations are then entered into the high / low voltage fault ride-through protection model of the wind turbine.

[0251] Simulation is performed using the high / low voltage fault ride-through control and protection model of wind turbines.

[0252] Among them, the simulation curves include: wind turbine terminal voltage simulation curve, wind turbine active power and reactive power simulation curve, grid connection point bus voltage simulation curve and grid connection line active power and reactive power simulation curve.

[0253] The event information includes: event information of high / low voltage fault ride-through control and protection action of the wind turbine.

[0254] According to the simulation analysis results, it is determined whether the wind turbines in the wind farm group have experienced fault ride-through. If so, the wind farm group is controlled using the reactive voltage control mode to prevent and control the fault ride-through under large and rapid fluctuations in wind power output, including:

[0255] Calculating SVG dynamic reactive power margin The wind farm group is controlled in the reactive voltage control mode, and the SVG dynamic reactive margin is adjusted according to the SVG dynamic reactive margin. Update the SVG reactive upper limit, and based on the updated SVG reactive upper limit, perform wind farm group output according to a fixed control cycle under the reactive voltage control model. The steady-state reactive voltage control model is modeled and solved, and the reactive output values ​​of wind turbines and SVGs obtained are regularly sent to wind farms. The dynamic reactive reserve reserved by SVG is used to prevent and control fault ride-through actions under large and rapid fluctuations in wind power output.

[0256] Among them, according to the simulation analysis results, determine whether the wind turbines in the wind farm group have fault ride-through action. If not, set the SVG dynamic reactive margin to =0, the wind farm group is controlled by the fixed-cycle steady-state reactive voltage control of the wind farm group, and the dynamic reactive margin is set according to the SVG being 0. Update the SVG reactive upper limit, and based on the updated SVG reactive upper limit, perform wind farm group output according to a fixed control cycle under the reactive voltage control model. The steady-state reactive power and voltage control model is modeled and solved, and the reactive power output values ​​of wind turbines and SVGs obtained by the solution are regularly sent to the wind farm.

[0257] The present invention standardizes the operation of reactive equipment such as multiple SVGs and multiple wind turbines in wind farms, optimizes the reactive voltage control of wind farm groups with gradually increasing grid-connected capacity and low short-circuit ratio, promotes the acceptance of new energy, and improves grid security.

[0258] Example 3:

[0259] Based on the same inventive concept, the present invention also provides a computer device, which includes a processor and a memory, wherein the memory is used to store a computer program, the computer program includes program instructions, and the processor is used to execute the program instructions stored in the computer storage medium. The processor may be a central processing unit (CPU), or may be other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, etc. It is the computing core and control core of the terminal, which is suitable for implementing one or more instructions, specifically suitable for loading and executing one or more instructions in the computer storage medium to implement the corresponding method flow or corresponding function, so as to implement the steps of the method in the above embodiment.

[0260] Example 4:

[0261] Based on the same inventive concept, the present invention also provides a storage medium, specifically a computer-readable storage medium (Memory), which is a memory device in a computer device for storing programs and data. It can be understood that the computer-readable storage medium here can include both built-in storage media in the computer device and, of course, extended storage media supported by the computer device. The computer-readable storage medium provides a storage space that stores the operating system of the terminal. In addition, one or more instructions suitable for being loaded and executed by the processor are also stored in the storage space. These instructions can be one or more computer programs (including program codes). It should be noted that the computer-readable storage medium here can be a high-speed RAM memory or a non-volatile memory, such as at least one disk memory. The processor can load and execute one or more instructions stored in the computer-readable storage medium to implement the steps of the method in the above embodiment.

[0262] It will be understood by those skilled in the art that the embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code. The solutions in the embodiments of the present invention may be implemented in various computer languages, for example, the object-oriented programming language Java and the interpreted scripting language JavaScript.

[0263] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowcharts and / or block diagrams, as well as combinations of processes and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowcharts and / or block diagrams. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0264] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0265] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0266] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0267] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A method for preventing and controlling fault ride-through actions under large and rapid fluctuations in wind power output, characterized in that: include: Establishing a grid access model for a group of wind farms, and generating a data file for simulation calculation based on the grid access model; Establish a reactive voltage control mode that coordinates the fixed-cycle steady-state reactive voltage control of the wind farm group with the fixed-voltage response control of the SVG equipment level of the wind farm group; Based on the data file, dynamically simulate the rapid and large-scale change characteristics of the wind farm group output, and obtain simulation analysis results of the dynamic impact on the wind power grid connection point and the wind turbine terminal voltage; Based on the simulation analysis results, it is determined whether the wind turbines in the wind farm group have experienced fault ride-through action. If so, the wind farm group is controlled using the reactive voltage control mode to prevent and control the fault ride-through action under large and rapid fluctuations in wind power output.

2. The method according to claim 1, characterized in that The establishment of a wind farm group access grid model includes: establishing steady-state and transient equivalent aggregation models of the wind farm, and establishing a steady-state model and a transient model of the wind farm group accessing the main grid based on the steady-state and transient equivalent aggregation models of the wind farm.

3. The method according to claim 2, characterized in that The step of establishing the equivalent aggregation model of the wind farm in steady state and transient state, and establishing the steady state model and transient model of the wind farm group connected to the main grid based on the equivalent aggregation model of the wind farm in steady state and transient state, includes: Based on the wind conditions, turbine types, and internal wiring forms within the wind farm, multiple wind turbines within the wind farm are aggregated to generate equivalent aggregate models of the wind farm in steady and transient states. Based on the steady-state and transient equivalent aggregation models of the wind farm, the wind power unit transformer, internal cables, grid-connected step-up transformer, supporting SVG and grid-connected lines are modeled. The main grid with a close electrical distance to the wind farm is modeled in detail, and the remaining main grids are modeled in an equivalent simplified manner to generate a steady-state model and a transient model of the wind farm group connected to the main grid.

4. The method according to claim 1, wherein The reactive voltage control mode includes: reserving a dynamic reactive margin of the wind farm group SVG, and using the wind farm group SVG device-level constant voltage response control to track voltage changes, automatically calling out the reserved dynamic reactive margin of the wind farm group SVG for preventing and controlling fault ride-through actions, and performing fixed-cycle steady-state reactive voltage control of the wind farm group based on the remaining SVG capacity after reserving the dynamic reactive margin of the wind farm group SVG and the reactive output of the wind turbines.

5. The method according to claim 1, wherein The method of dynamically simulating the rapid and substantial changes in wind farm group output according to the data file includes: Determine the basic output of the wind farm group based on the data file Wind conditions and historical output of wind farm groups; Based on the basic output of wind farm groups Based on the wind conditions and historical output of the wind farm group, the rapid and large changes in the output of the wind farm group are predicted; Dynamically simulate the rapid and drastic changes in wind farm output.

6. The method according to claim 1, wherein The dynamic simulation results include: simulation curves of wind farm group output changes.

7. The method according to claim 1, characterized in that The obtaining of simulation analysis results based on the dynamic simulation results includes: Based on the dynamic simulation results, according to the basic output of the wind farm group The simulation determines the rapid and large-scale change characteristics of the wind farm group output under the operating status, and the dynamic impact on the wind power grid connection point and the voltage fluctuation of the wind turbine terminal. Based on the dynamic impact, the simulation curves and event information of the wind turbine fault ride-through action and the impact on the safety and stability of the power grid are determined.

8. The method according to claim 7, characterized in that The operating status includes reactive voltage and active phase angle.

9. The method according to claim 7, characterized in that When simulating and determining the rapid and large-scale changes in the output of the wind farm group and the dynamic impact of voltage fluctuations at the wind power grid connection point and wind turbine terminal, the wind turbine and SVG maintain the initial reactive power value unchanged.

10. The method according to claim 7, characterized in that The method further includes: establishing a high / low voltage fault ride-through control and protection model for the wind turbine; The typical envelope corresponding to the high / low voltage fault ride-through protection function of the wind turbine is discretized, and the action voltage threshold and duration are given for each discrete point. Multiple discrete points and the corresponding action voltage thresholds and durations are then entered into the high / low voltage fault ride-through protection model of the wind turbine. Simulation is performed using the high / low voltage fault ride-through control and protection model of wind turbines.

11. The method according to claim 7, characterized in that The simulation curves include: a wind turbine terminal voltage simulation curve, a wind turbine active power and reactive power simulation curve, a grid-connected point bus voltage simulation curve, and a grid-connected line active power and reactive power simulation curve.

12. The method according to claim 7, characterized in that The event information includes: event information of high / low voltage fault ride-through control and protection action of the wind turbine generator set.

13. The method according to claim 1, wherein The method further comprises: determining whether the wind turbines in the wind farm group have experienced a fault ride-through action based on the simulation analysis results; and if so, controlling the wind farm group in the reactive voltage control mode to prevent and control the fault ride-through action under the condition of large and rapid fluctuations in wind power output, including: Calculating SVG dynamic reactive power margin The wind farm group is controlled in the reactive voltage control mode, and the SVG dynamic reactive margin is adjusted according to the SVG dynamic reactive margin. Update the SVG reactive upper limit, and based on the updated SVG reactive upper limit, perform wind farm group output according to a fixed control cycle under the reactive voltage control model. The steady-state reactive voltage control model is modeled and solved, and the reactive output values ​​of wind turbines and SVGs obtained are regularly sent to wind farms. The dynamic reactive reserve reserved by SVG is used to prevent and control fault ride-through actions under large and rapid fluctuations in wind power output.

14. The method according to claim 13, characterized in that According to the simulation analysis results, it is determined whether the wind turbines in the wind farm group have experienced fault ride-through action. If not, the SVG dynamic reactive margin is set to =0, the wind farm group is controlled by the fixed-cycle steady-state reactive voltage control of the wind farm group, and the dynamic reactive margin is set according to the SVG being 0. Update the SVG reactive upper limit, and based on the updated SVG reactive upper limit, perform wind farm group output according to a fixed control cycle under the reactive voltage control model. The steady-state reactive power and voltage control model is modeled and solved, and the reactive power output values ​​of wind turbines and SVGs obtained by the solution are regularly sent to the wind farm.

15. A system for preventing and controlling fault ride-through under large and rapid fluctuations in wind power output, characterized in that: include: An initialization unit is used to establish a grid access model for a group of wind farms and generate a data file for simulation calculation based on the grid access model; Establish a reactive voltage control mode that coordinates the fixed-cycle steady-state reactive voltage control of the wind farm group with the fixed-voltage response control of the SVG equipment level of the wind farm group; A simulation unit, configured to dynamically simulate the rapid and substantial changes in wind farm group output characteristics based on the data file, and obtain simulation analysis results of the dynamic impact on the wind power grid connection point and the wind turbine terminal voltage; The control unit is used to determine whether the wind turbines in the wind farm group have experienced fault ride-through action based on the simulation analysis results. If so, the wind farm group is controlled in the reactive voltage control mode to prevent and control the fault ride-through action under large and rapid fluctuations in wind power output.

16. The system according to claim 15, wherein: The establishment of a wind farm group access grid model includes: establishing steady-state and transient equivalent aggregation models of the wind farm, and establishing a steady-state model and a transient model of the wind farm group accessing the main grid based on the steady-state and transient equivalent aggregation models of the wind farm.

17. The system according to claim 16, wherein: The step of establishing the equivalent aggregation model of the wind farm in steady state and transient state, and establishing the steady state model and transient model of the wind farm group connected to the main grid based on the equivalent aggregation model of the wind farm in steady state and transient state, includes: Based on the wind conditions, turbine types, and internal wiring forms within the wind farm, multiple wind turbines within the wind farm are aggregated to generate equivalent aggregate models of the wind farm in steady and transient states. Based on the steady-state and transient equivalent aggregation models of the wind farm, the wind power unit transformer, internal cables, grid-connected step-up transformer, supporting SVG and grid-connected lines are modeled. The main grid with a close electrical distance to the wind farm is modeled in detail, and the remaining main grids are modeled in an equivalent simplified manner to generate a steady-state model and a transient model of the wind farm group connected to the main grid.

18. The system according to claim 15, wherein: The reactive voltage control mode includes: reserving a dynamic reactive margin of the wind farm group SVG, and using the wind farm group SVG device-level constant voltage response control to track voltage changes, automatically calling out the reserved dynamic reactive margin of the wind farm group SVG for preventing and controlling fault ride-through actions, and performing fixed-cycle steady-state reactive voltage control of the wind farm group based on the remaining SVG capacity after reserving the dynamic reactive margin of the wind farm group SVG and the reactive output of the wind turbines.

19. The system according to claim 15, wherein: The method of dynamically simulating the rapid and substantial changes in wind farm group output according to the data file includes: Determine the basic output of the wind farm group based on the data file Wind conditions and historical output of wind farm groups; Based on the basic output of wind farm groups Based on the wind conditions and historical output of the wind farm group, the rapid and large changes in the output of the wind farm group are predicted; Dynamically simulate the rapid and drastic changes in wind farm output.

20. The system according to claim 15, wherein: The dynamic simulation results include: simulation curves of wind farm group output changes.

21. The system according to claim 15, wherein: The obtaining of simulation analysis results based on the dynamic simulation results includes: Based on the dynamic simulation results, according to the basic output of the wind farm group The simulation determines the rapid and large-scale change characteristics of the wind farm group output under the operating status, and the dynamic impact on the wind power grid connection point and the voltage fluctuation of the wind turbine terminal. Based on the dynamic impact, the simulation curves and event information of the wind turbine fault ride-through action and the impact on the safety and stability of the power grid are determined.

22. The system according to claim 21, wherein: The operating status includes reactive voltage and active phase angle.

23. The system according to claim 21, wherein: When simulating and determining the rapid and large-scale changes in the output of the wind farm group and the dynamic impact of voltage fluctuations at the wind power grid connection point and wind turbine terminal, the wind turbine and SVG maintain the initial reactive power value unchanged.

24. The system according to claim 21, wherein: The obtaining of simulation analysis results based on the dynamic simulation results also includes: establishing a high / low voltage fault ride-through control and protection model for the wind turbine; The typical envelope corresponding to the high / low voltage fault ride-through protection function of the wind turbine is discretized, and the action voltage threshold and duration are given for each discrete point. Multiple discrete points and the corresponding action voltage thresholds and durations are then entered into the high / low voltage fault ride-through protection model of the wind turbine. Simulation is performed using the high / low voltage fault ride-through control and protection model of wind turbines.

25. The system according to claim 21, wherein The simulation curves include: a wind turbine terminal voltage simulation curve, a wind turbine active power and reactive power simulation curve, a grid-connected point bus voltage simulation curve, and a grid-connected line active power and reactive power simulation curve.

26. The system according to claim 21, wherein The event information includes: event information of high / low voltage fault ride-through control and protection action of the wind turbine generator set.

27. The system according to claim 21, wherein: The method further comprises: determining whether the wind turbines in the wind farm group have experienced fault ride-through based on the simulation analysis results; and if so, controlling the wind farm group in the reactive voltage control mode to prevent and control the fault ride-through under the condition of large and rapid fluctuations in wind power output, including: Calculating SVG dynamic reactive power margin The wind farm group is controlled in the reactive voltage control mode, and the SVG dynamic reactive margin is adjusted according to the SVG dynamic reactive margin. Update the SVG reactive upper limit, and based on the updated SVG reactive upper limit, perform wind farm group output according to a fixed control cycle under the reactive voltage control model. The steady-state reactive voltage control model is modeled and solved, and the reactive output values ​​of wind turbines and SVGs obtained are regularly sent to wind farms. The dynamic reactive reserve reserved by SVG is used to prevent and control fault ride-through actions under large and rapid fluctuations in wind power output.

28. The system according to claim 27, wherein: According to the simulation analysis results, it is determined whether the wind turbines in the wind farm group have experienced fault ride-through action. If not, the SVG dynamic reactive margin is set to =0, the wind farm group is controlled by the fixed-cycle steady-state reactive voltage control of the wind farm group, and the dynamic reactive margin is set according to the SVG being 0. Update the SVG reactive upper limit, and based on the updated SVG reactive upper limit, perform wind farm group output according to a fixed control cycle under the reactive voltage control model. The steady-state reactive power and voltage control model is modeled and solved, and the reactive power output values ​​of wind turbines and SVGs obtained by the solution are regularly sent to the wind farm.

29. A computer device, characterized in that: include: one or more processors; a processor for executing one or more programs; When the one or more programs are executed by the one or more processors, the method according to any one of claims 1 to 14 is implemented.

30. A computer-readable storage medium, characterized in that A computer program is stored thereon, and when the computer program is executed, the method according to any one of claims 1 to 14 is implemented.

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