Wind field reactive voltage control method and system for preventing and controlling fault ride-through action under large-amplitude rapid fluctuation of wind power output

Abstract

The invention discloses a wind field reactive voltage control method and system for preventing and controlling a fault ride-through action under large-amplitude rapid fluctuation of wind power output, and belongs to the technical field of new energy grid connection. The method comprises the steps that a wind power plant group access power grid model is established, and a data file used for simulation calculation is generated based on the access power grid model; establishing a reactive voltage control mode in which wind power plant group fixed-period steady-state reactive voltage control and wind power plant group SVG equipment-level fixed voltage response control are coordinated; according to the data file, carrying out dynamic simulation on the rapid and large-amplitude change characteristics of the output of the wind power plant group, and obtaining a simulation analysis result having dynamic influence on the voltage of a wind power grid-connected point and the voltage of a wind motor; and the fault ride-through action under great and rapid fluctuation of wind power output is prevented and controlled. According to the method, actions of reactive equipment such as multiple SVGs and multiple wind turbine generators of the wind power plant are standardized, reactive voltage control of the wind power plant group under the condition that the grid-connected capacity is gradually increased and the short-circuit ratio is low is optimized, and new energy acceptance is promoted.

Description

Technical Field

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

[0002] After the wind farm is connected to the power grid, it should meet the operating objectives such as reactive layering and zoning balance, voltage safety and voltage quality. According to the requirements of the standard "Technical Regulations for Wind Farm Access to Power System", the wind farm needs to be equipped with reactive sources of certain capacity and different types, including wind turbines that can output reactive power and reactive compensation devices such as static VAR generators (SVG). After the wind farm is put into operation, it is necessary to control the reactive voltage of the wind farm, optimize the reactive output of the wind turbine units or reactive sources such as SVG in the field, and achieve the voltage amplitude and voltage fluctuation rate of the wind farm grid connection point under various operating conditions within a reasonable range, and the voltage in the field meets the upper and lower limit constraints and other operating objectives; moreover, the wind farm should provide dynamic reactive support for the power grid according to the needs of the power grid, and maintain the voltage stability of the wind farm connected to the power grid and the reliable operation of the units.

[0003] The following aspects of wind farm reactive voltage control have been studied, including: research on wind farm reactive voltage control mode and coordinated control mode with the main grid; research on wind farm reactive voltage control optimization model and control strategy solution, etc.: 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 means of wind farms, including wind turbines, dynamic reactive compensation and other means; 3) control strategy solution method, etc. In my country's three-level voltage control system, the reactive voltage of wind farm groups generally belongs to the regional voltage control level. The reactive voltage control of the upper level usually takes grid loss, voltage quality and voltage safety as optimization goals, considers the coordination of various reactive sources, and optimizes the voltage control target value or range of each wind farm control bus (usually the grid-connected bus). The target voltage of the control bus is sent to each area containing the wind farm group to control the regional reactive voltage. The control cycle is generally in the minute level. According to the active / reactive power, voltage and other working conditions of the power grid in the control area, the reactive voltage optimization of this area is carried out taking into account the wind farm, conventional generator sets, various substations and other controllable reactive sources in the area. In addition to tracking the voltage of each wind farm grid connection point sent down, more optimization goals and constraints related to the wind farm can also be considered to achieve refined coordinated control of wind farm reactive equipment. The patent content of this invention belongs to the technical field of regional reactive voltage control of wind farm groups.

[0004] As the capacity of wind power grid connection increases gradually, the short-circuit ratio of wind power continues to decrease, the "fixed voltage" capacity of wind power access areas decreases, and fault disturbances bring greater voltage fluctuations, which can easily cause the voltage at the grid connection point and the voltage at the wind turbine end to exceed the limit. Since the voltage resistance and overload capacity of power electronic equipment of wind turbines are weak, high / low voltage fault ride-through control and protection functions are required. When the disturbance causes the terminal voltage to reach the fault ride-through threshold, the fault ride-through reactive dynamic control action is used to assist the wind turbine to successfully complete the fault ride-through. However, if the fault disturbance is more serious or the grid structure of the connected power grid is weak, the wind turbine cannot complete the fault ride-through after a period of time. At this time, the fault ride-through protection action is activated and the wind turbine is cut off. The change of wind power output can also be regarded as a disturbance. It has the characteristics of rapid, large, and intermittent changes. When the grid structure of the connected power grid is weak, the voltage will change sharply. If the wind farm cannot take timely and effective reactive voltage control, the voltage fluctuation may trigger the high / low voltage fault ride-through control and protection action of the wind turbine, affecting the stable operation of the power grid. 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 voltage control to further improve the reliability and safety of wind power grid-connected operation.

[0005] The main reactive equipment in a wind farm includes wind turbines and SVG, which have different characteristics: ① The capacity of a single wind turbine is relatively small, but there are many wind turbines in a wind farm. For a typical 300MW wind farm, there are 48 wind turbines with a single capacity of 6.25MW, while SVG is generally configured with 2 to 3 sets, which is a relatively small number; ② The reactive power output by the wind turbine needs to be coordinated with the active power of the unit, while SVG only outputs reactive power, with relatively fewer regulation constraints and more convenient control; ③ The reactive voltage response time of the wind turbine converter is generally 20 to 60ms, while the reactive voltage response time of SVG is generally around 20ms. Relatively speaking, SVG is more adaptable to regulation under rapidly changing working conditions. In the case of rapid and substantial changes in wind power output in weak power grids, prevention and control of reactive voltage fluctuations that trigger wind power fault ride-through generally requires that the reactive equipment in the wind farm 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 in the farm is small in capacity, large 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. The following should be considered in the formulation of reactive voltage control strategies: ① The reactive output of reactive equipment responsive control causes a large jump in voltage and other operating conditions. If the responsive control strategies and parameter settings of multiple sets of reactive equipment are not matched or coordinated, the interaction of 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 SVG in wind farm groups on a ms or even faster time scale are prone to induce 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 weak power grid wind farm groups, 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 steady-state reactive voltage optimization, the relevant wind farm reactive voltage control models, control modes and strategies need to be further studied, so as to more fully coordinate and standardize the actions of multiple power electronic reactive equipment in the wind farm, so as to further improve the economy, reliability and safety of wind power grid-connected reactive voltage operation. Summary of the invention

[0006] In view of the above problems, 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-connected model for a group of wind farms, and generating a data file for simulation calculation based on the grid-connected model;

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

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

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

[0011] Optionally, establishing a model for connecting a group of wind farms to a power grid includes: establishing steady-state and transient equivalent aggregation models of the wind farms, and establishing a steady-state model and a transient model for connecting the group of wind farms to a main grid based on the steady-state and transient equivalent aggregation models of the wind farms.

[0012] Optionally, 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, including:

[0013] According to the wind conditions, unit types and internal wiring forms in the wind farm, multiple wind turbines in the wind farm are aggregated to generate equivalent aggregation models of the wind farm in steady state and transient state;

[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 that is close to the wind farm in electrical distance 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] Optional reactive voltage control mode, including: reserving dynamic reactive margin of wind farm group SVG, and using wind farm group SVG equipment-level constant voltage response control to track voltage changes, automatically calling out the reserved dynamic reactive margin of 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, according to the data file, a dynamic simulation is performed on the rapid and large-scale change characteristics of the wind farm group output, including:

[0017] According to the data file, determine the basic output of the wind farm group Wind conditions and historical output of wind farm groups;

[0018] 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;

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

[0020] Optionally, 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 wind farm groups 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 unit 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 the voltage fluctuation changes at the wind power grid connection point and the wind turbine generator set terminal, the wind turbine generator set and the 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 threshold and duration of the action voltage are given for each discrete point, and multiple discrete points and the corresponding threshold and duration of the action voltage are filled into the high / low voltage fault ride-through protection model of the wind turbine;

[0027] Simulation is performed through 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, including: event information of high / low voltage fault ride-through control and protection action of wind turbine.

[0030] Optionally, according to the simulation analysis results, it is determined whether the wind turbines in the wind farm group have a fault ride-through action. If so, the wind farm group is controlled in the reactive voltage control mode to prevent and control the fault ride-through action under the large and rapid fluctuation of 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 set according to the reactive voltage control mode. Update the SVG reactive power upper limit, and based on the updated SVG reactive power upper limit, perform wind farm group output according to a fixed control cycle under the reactive power voltage control model. The steady-state reactive voltage control model 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 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 power margin to is 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 power upper limit, and based on the updated SVG reactive power upper limit, perform wind farm group output according to a fixed control cycle under the reactive power voltage control model. The steady-state reactive voltage control model 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.

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

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

[0035] A simulation unit, for dynamically simulating the rapid and large-scale change characteristics of the wind farm group output according to the data file, and obtaining 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 fault ride-through action 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 action under the condition of large and rapid fluctuations in wind power output.

[0037] Optionally, establishing a model for connecting a group of wind farms to a power grid includes: establishing steady-state and transient equivalent aggregation models of the wind farms, and establishing a steady-state model and a transient model for connecting the group of wind farms to a main grid based on the steady-state and transient equivalent aggregation models of the wind farms.

[0038] Optionally, 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, including:

[0039] According to the wind conditions, unit types and internal wiring forms in the wind farm, multiple wind turbines in the wind farm are aggregated to generate equivalent aggregation models of the wind farm in steady state and transient state;

[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 that is close to the wind farm in electrical distance 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] Optional reactive voltage control mode, including: reserving dynamic reactive margin of wind farm group SVG, and using wind farm group SVG equipment-level constant voltage response control to track voltage changes, automatically calling out the reserved dynamic reactive margin of 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, according to the data file, a dynamic simulation is performed on the rapid and large-scale change characteristics of the wind farm group output, including:

[0043] According to the data file, determine the basic output of the wind farm group Wind conditions and historical output of wind farm groups;

[0044] 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;

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

[0046] Optionally, 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 wind farm groups 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 unit 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 the voltage fluctuation changes at the wind power grid connection point and the wind turbine generator set terminal, the wind turbine generator set and the 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 threshold and duration of the action voltage are given for each discrete point, and multiple discrete points and the corresponding threshold and duration of the action voltage are filled into the high / low voltage fault ride-through protection model of the wind turbine;

[0053] Simulation is performed through 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, including: event information of high / low voltage fault ride-through control and protection action of wind turbine.

[0056] Optionally, according to the simulation analysis results, it is determined whether the wind turbines in the wind farm group have a fault ride-through action. If so, the wind farm group is controlled in the reactive voltage control mode to prevent and control the fault ride-through action under the large and rapid fluctuation of 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 set according to the reactive voltage control mode. Update the SVG reactive power upper limit, and based on the updated SVG reactive power upper limit, perform wind farm group output according to a fixed control cycle under the reactive power voltage control model. The steady-state reactive voltage control model 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 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 power margin to is 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 power upper limit, and based on the updated SVG reactive power upper limit, perform wind farm group output according to a fixed control cycle under the reactive power voltage control model. The steady-state reactive voltage control model 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.

[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 yet 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 actions under large and rapid fluctuations in wind power output, including: 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; according to the data file, dynamically simulating the rapid and large-scale change characteristics of the wind farm group's output, and obtaining simulation analysis results that have a dynamic impact on the wind power grid connection point and the wind turbine terminal voltage; according to the simulation analysis results, determining whether the wind turbines of the wind farm group have a fault ride-through action, and if so, controlling the wind farm group with the reactive voltage control mode to prevent and control the fault ride-through action 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-connected capacity and low short-circuit ratio, promotes the acceptance of new energy, and improves the safety of the power grid. 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 A simulation curve diagram showing rapid and substantial changes in wind farm output according to an embodiment of the method of the present invention;

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

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

[0070] Figure 6 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 method embodiment 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] Fig. 9 It 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] Fig.10 It is a simulation curve diagram of the terminal voltage of the wind turbine generator set in the dlf wind farm of the method embodiment of the present invention;

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

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

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

[0078] Fig.14 A schematic diagram of wind farm wind power, SVG reactive output, wind turbine terminal, grid connection point voltage and access power flow distribution after reactive voltage optimization of wind farm group in an embodiment of the method of the present invention;

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

[0080] Fig.16 A schematic diagram of simulation results of the voltages of the wind turbine terminals, the grid-connected bus and the main grid bus of the wind farm when the wind farm group output changes significantly and rapidly, for the electric farm group SVG of the method embodiment of the present invention, with dynamic reactive power reserved and a constant voltage response control strategy adopted;

[0081] Fig.17 It is a schematic diagram of the simulation of the dynamic reactive power output of the SVG of the wind farm group when the output of the wind farm group changes greatly and rapidly according to the method embodiment of the present invention;

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

[0083] Now, exemplary embodiments of the present invention are described with reference to the accompanying drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are provided to disclose the present invention in detail and completely and to fully convey the scope of the present invention to those skilled in the art. The terms used in the exemplary embodiments shown in the accompanying drawings are not intended to limit the present invention. In the accompanying drawings, the same units / elements are marked with the same reference numerals.

[0084] Unless otherwise specified, the terms (including technical terms) used herein have the commonly understood meanings to those skilled in the art. In addition, it is understood that the 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] Embodiment 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 As 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-period steady-state reactive voltage control with the wind farm group's SVG equipment-level constant voltage response control;

[0089] Step 3: According to the data file, dynamically simulate the rapid and large-scale change characteristics of the wind farm group output, and obtain simulation analysis results that have a 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 a fault ride-through action according to the simulation analysis results. If so, control 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.

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

[0092] Among them, 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, including:

[0093] According to the wind conditions, unit types and internal wiring forms in the wind farm, multiple wind turbines in the wind farm are aggregated to generate equivalent aggregation models of the wind farm in steady state and transient state;

[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 that is close to the wind farm in electrical distance 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 adopting 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.

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

[0097] According to the data file, determine the basic output of the wind farm group Wind conditions and historical output of wind farm groups;

[0098] 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;

[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 wind farm groups 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 unit 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] Among them, 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 threshold and duration of the action voltage are given for each discrete point, and multiple discrete points and the corresponding threshold and duration of the action voltage are filled into the high / low voltage fault ride-through protection model of the wind turbine;

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

[0108] The simulation curves include: wind turbine terminal voltage simulation curve, wind turbine active power and reactive power simulation curve, grid-connected point bus voltage simulation curve, and grid-connected 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 wind turbines.

[0110] According to the simulation analysis results, it is determined whether the wind turbines in the wind farm group have a fault ride-through action. If so, the wind farm group is controlled in the reactive voltage control mode to prevent and control the fault ride-through action under the large and rapid fluctuation of 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 set according to the reactive voltage control mode. Update the SVG reactive power upper limit, and based on the updated SVG reactive power upper limit, perform wind farm group output according to a fixed control cycle under the reactive power voltage control model. The steady-state reactive voltage control model 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 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 power margin is 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 power upper limit, and based on the updated SVG reactive power upper limit, perform wind farm group output according to a fixed control cycle under the reactive power voltage control model. The steady-state reactive voltage control model 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.

[0113] The present invention is further described below in conjunction with specific implementation cases:

[0114] Specific implementation case process is as follows Figure 2 As 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 to generate data files for simulation calculations.

[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 constant 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 changes in the output of the wind farm group are predicted, and the PSD simulation program is used to dynamically simulate the rapid and large changes in the output of the wind farm group.

[0118] (4) Using the PSD simulation program, based on the basic output of the wind farm group The reactive voltage, active phase angle and other operating conditions under the simulated conditions are taken into consideration. The wind turbines and SVG maintain the initial reactive values ​​unchanged. The simulation analyzes the dynamic impact of the rapid and substantial changes in the output of the wind farm group on the voltage fluctuations 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 no wind turbine fault ride-through occurs, set the SVG dynamic reactive power margin to is 0, and jumps 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 occurs and affects the stable operation of the power grid, the SVG dynamic reactive margin is performed , 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 fixed 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 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 action under large and rapid fluctuations in wind power output.

[0122] Preferably, the step (1) comprises:

[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 a 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 impact range of wind farm group aggregation, access and transmission, the main grid is modeled in detail or simplified. Generally, the regional power grid to which the wind farm group is connected needs to be modeled in detail, and the main grid outside the regional power grid can be modeled in an equivalent and simplified manner according to the situation.

[0124] Preferably, the step (2) comprises:

[0125] The reactive voltage control mode of the wind farm group fixed-period steady-state reactive voltage control coordinated with the wind farm SVG equipment-level constant voltage response control is further explained, namely: when the wind farm SVG has sufficient reactive power, the SVG equipment-level constant voltage response control 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 wind farm grid connection point and the terminal voltage within a given range, and deal with the fault ride-through problem that may occur due to voltage fluctuations; after reserving the dynamic reactive capacity of the SVG to deal with fault ride-through, the SVG of 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, and at the same time, multiple objectives such as minimizing the reactive control amount and balancing the reactive control amount among multiple wind turbines in the wind farm and among multiple sets of SVG are achieved.

[0126] Preferably, the step (3) comprises:

[0127] Based on the PSD power system dynamic simulation program, the IGV model of renewable energy power generation output 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 characterize the change in wind power output are filled into the IGV model. By running the PSD program, a simulation curve of 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) comprises:

[0129] Based on the PSD program, a high / low voltage fault ride-through control and protection model for wind turbines is established. Based on the PSD program, a dynamic model of a wind turbine with multiple control function modules is established. The structure of the dynamic model of a wind turbine 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——doubly fed, direct drive generator models;

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

[0132] WEV model——fault-travel 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 of a wind turbine 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 such as Figure 5 As shown:

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

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

[0143] Wind turbine terminal voltage simulation curve;

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

[0145] Grid connection point bus voltage simulation curve;

[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) comprises:

[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 basic operating state is set, and the wind farm SVG is set as the response control strategy for the target bus voltage (generally the grid connection point). The upper and lower limits of SVG reactive power are set to a custom larger value (the SVG output reactive power will not reach the upper limit due to the set limit being too small). Based on the PSD dynamic simulation analysis program, the reactive output increment of 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 wind farm SVG are established based on the PSD program. The control strategy adopted by SVG is a responsive control strategy that sets the target bus voltage as a given value. This strategy simulates the dynamic function of automatically adjusting the reactive output within the upper and lower limits of SVG reactive power to maintain the target bus voltage to a given value when the voltage fluctuates due to rapid changes in wind power output.

[0153] The SVG model structure is as follows Figure 6 As shown, 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 leading time constant (seconds);

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

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

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

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

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

[0166] K D , the slope of the VI characteristic curve of SVG 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 when the wind power output changes rapidly and significantly. 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 substantial 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) comprises:

[0176] The steady-state reactive voltage optimization control of the regional wind farm group is based on the principle of giving priority to the SVG of 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 goals, 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, which represents the reactive power regulation of the equipment; the subscript w represents the wind turbine, and the subscript s represents the SVG. The upper and lower limits of the reactive power of the i-th wind turbine in the wind farm should be dynamically adjustable within the range of leading 0.95 to lagging 0.95 under the rated active power output according to the grid connection guidelines, 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 a 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] The following constraints are met:

[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 vector 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; They are 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; is the voltage optimization setting value of each wind farm control bus (generally the grid connection point), which 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 the objective function (5); 2) the reactive adjustment of wind turbines and SVG in the wind farm is minimized, corresponding to the second and third items in the objective function (5); 3) the reactive adjustment of wind turbines in the wind farm is evenly distributed among multiple wind turbines, and the reactive adjustment of SVG is evenly distributed among multiple SVGs, corresponding to the fourth item in the objective function (5). W c , W qw , W qs and W m are the weights of each sub-objective function. Since the wind farm SVG has the characteristics of a small number of units, only reactive power output and fast action speed, from the perspective of meeting the timeliness of voltage control under rapid and large wind power changes, and the response action of a small number of power electronic equipment can reduce the risks of control oscillation and broadband oscillation, and considering the advantages of SVG only outputting reactive power such as control decoupling, this patent selects SVG to take precedence over wind turbines for steady-state reactive voltage regulation after reserving SVG dynamic reactive power, and realizes the action priority by setting the weights of wind turbine and SVG adjustment amount in objective function (5), that is: W qs The weight is much smaller than W qw .

[0194] The present invention adopts sequential linear programming (SLP) to solve control models (5) to (8), linearizes the above nonlinear optimization problem multiple times, and solves it based on linear programming, that is, adopts SLP 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 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 conduct risk assessment of wind power high / low voltage fault ride-through with large and rapid changes in wind farm group output under weak power grid. In view of possible fault ride-through problems, a reactive voltage control mode that coordinates wind farm group fixed-cycle steady-state reactive voltage control with wind farm SVG equipment-level constant voltage response control is proposed, giving full play to SVG's advantages such as fast action speed, small number of sets in the field, and only reactive output. Advantages, using SVG to reserve dynamic reactive margin and perform constant voltage response control strategy to prevent and control fault ride-through action; considering SVG to reserve part of the dynamic reactive capacity, and then coordinate the fixed-period steady-state reactive voltage optimization control of the remaining SVG capacity and wind turbines and other reactive equipment. Steady-state reactive voltage control also takes SVG as the principle of priority action, and then coordinates the reactive output of multiple wind turbines to achieve steady-state reactive voltage multi-objective optimization, including: grid-connected point voltage maintains a given value, and the reactive control amount is minimized and the equipment control amount is evenly distributed. In the proposed control mode, a smaller number of power electronic equipment SVGs take precedence over a larger number of power electronic equipment wind turbines, which can further reduce the dynamic (transient) risks such as switching control oscillation and broadband oscillation. Combining the above aspects, a more reasonable optimization and coordination of steady-state and dynamic (transient) reactive voltages is carried out from the aspects of reactive voltage modeling and control mode formulation.

[0197] 2) A calculation method for the dynamic reactive power reserved by SVG is proposed, which can be used to decompose and coordinate the steady-state reactive voltage control and the dynamic reactive voltage control for preventing and controlling the fault ride-through action: First, the SVG constant voltage response control strategy is simulated based on the PSD dynamic program, and the dynamic reactive power that should be reserved for the fault ride-through action under the prevention and control of unexpected large and rapid changes in wind power output is calculated and quantified. Then, taking into account the SVG after reserving a part of reactive power, the reactive power coordinated optimization output of the wind farm group wind turbines and SVG under a fixed control cycle is carried out, realizing the decomposition and coordination of steady-state and dynamic (transient) reactive voltage control. At the same time, the dynamic response of SVG is simulated by the power system dynamic simulation program, and the dynamic reactive power reserve of SVG can be calculated more accurately.

[0198] 3) A method of integrating reactive voltage dynamic simulation 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 in 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 with gradually increasing grid-connected capacity and low short-circuit ratio is optimized, which promotes the acceptance of new energy and improves the safety of the power grid.

[0200] The following takes the access of a certain wind farm group to the power grid as an example to further describe the specific implementation mode 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 are 200MW respectively, and the installed capacity of hlf and dlf wind farms are 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 collected and connected to the 35 / 220kV booster stations mq, hn, hl, and dl in each wind farm, boosted to 220kV and connected to the grid. The mqf and hnf wind farms are each equipped with two SVGs with a single capacity of 18Mvar on the 35kV side of their respective booster transformers mq and hn. The total amount of SVG in each farm is 36Mvar, and the upper and lower limits of SVG reactive capacity are 36Mvar and -36Mvar respectively; the hlf and dlf wind farms are each equipped with two SVGs with a single capacity of 23Mvar on the 35kV side of their respective booster transformers hl and dl. The total amount of SVG in each farm is 46Mvar, and the upper and lower limits of SVG reactive capacity are 46Mvar and -46Mvar respectively. The upper and lower limits of the reactive power of the wind farm are dynamically adjustable within the range of 0.95 leading to 0.95 lagging according to the power factor under the rated active power of the wind farm. The upper and lower limits of the reactive power of the mqf and hnf wind farms are 66Mvar and -66Mvar respectively; the upper and lower limits of the reactive power of the hlf and dlf wind farms are 99Mvar and -99Mvar respectively. After part of the installed capacity wind power is consumed by the local load, the remaining power is sent through the 500kV substation mld. The regional power grid where the wind farm group is connected has no conventional power sources such as thermal power plants directly connected, only a 1000MW wind farm group.

[0202] Based on the typical access mode of wind farm groups, the research is carried out. 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 have an average output of 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 transmitted through 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 in the four wind farms mqf, hlf, dlf, and hnf is 0, and the reactive output of the SVG 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 sends the wind farm grid connection point to control the bus voltage setting range between 230 and 232kV, of which mq is 230.3kV, hl is 231.7kV, dl is 231.8kV, and hn is 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 Fig. 9 As shown:

[0206] Based on the rapid growth of the wind farm group's basic output of 800MW, the initial reactive power of wind turbines in each wind farm is 0Mvar, and the initial reactive power of SVG in mqf, hlf, dlf, and hnf wind farms is 24Mvar, 26Mvar, 26Mvar, and 22Mvar respectively. During the growth of wind power output, the reactive power of wind turbines and SVG remains unchanged at the initial value. The PSD dynamic simulation program is used to evaluate the risk of wind turbine fault ride-through caused by the rapid and substantial growth of wind power output. Through simulation analysis, in the process of rapid growth of wind power output, since the wind farm did not provide dynamic reactive power support in time, the voltage of each wind farm grid connection point and wind turbine continued to drop, triggering the dynamic control action of wind turbine fault ride-through. Wind turbines frequently enter and exit low-voltage fault ride-through, and wind turbines cannot operate reliably. At the same time, the main grid bus voltage and active power flow oscillate, affecting the stable operation of the power grid. Taking the dlf wind farm as an example, the simulation curve output of the wind turbine terminal voltage, grid-connected bus voltage, main grid 500kV station mld bus voltage, and active power through the mld station is as follows Fig.10 , 11 and 12;

[0207] A reactive voltage control mode that coordinates fixed-cycle reactive voltage optimization control at the station level with constant voltage response control at the SVG equipment level is established to prevent and control fault ride-through actions under rapid and significant changes in the output of weak power grid wind farm groups. The key to the SVG constant voltage response control strategy is to calculate the dynamic reactive power margin that needs to be reserved 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-connected bus), and the upper and lower limits of SVG reactive power are given to a larger value (to ensure that the actual SVG output reactive power will not reach the limit value). The simulation simulates the rapid and substantial increase in the output of the wind farm group. In order to maintain the grid-connected bus voltage at a given value, the maximum reactive power output of each wind farm SVG is subtracted from 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 power output simulation curve of a single SVG with a rated capacity of 23Mvar is as follows: Fig.13 As shown:

[0208] The hlf wind farm has a single SVG with a capacity of 23Mvar, an initial output of 13Mvar, and a maximum dynamic reactive output of 27.8Mvar. The dynamic reactive margin of the SVG required to be reserved for the fault ride-through action is 14.8Mvar. The dynamic reactive margin reserved by the two SVGs in the hlf wind farm is a total of 29.6Mvar, which can be given as 30Mvar. After calculation, the dynamic reactive margin reserved by the two SVGs in the other dlf, mqf, and hnf wind farms is 30Mvar, 23Mvar, and 30Mvar respectively.

[0209] Through the following formula Update SVG reactive caps where is the rated capacity of the wind farm SVG, Dynamic reactive power margin is reserved for wind farm SVG. The rated capacities of SVG for hlf, dlf, mqf and hnf wind farms are 46Mvar, 46Mvar, 36Mvar and 36Mvar respectively, and 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 They are 16Mvar, 16Mvar, 13Mvar, and 6Mvar respectively. Each wind farm has two SVGs. Therefore, the power of a single SVG is They are 8Mvar, 8Mvar, 6Mvar (rounded to 6.5Mvar), and 3Mvar respectively. The upper and lower limits of the capacity of a single SVG in each wind farm of hlf, dlf, mqf, and hnf are -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 amplitude in the "Schematic diagram of power flow distribution of wind farm group access to the grid and wind farm uniform output 80% typical mode"; in this mode hlf, dlf, mqf, hnf, the current reactive output of wind turbines in each wind farm is 0Mvar, and the reactive output of SVG is 26Mvar (single 13Mvar), 26Mvar (single 13Mvar), 24Mvar (single 12Mvar), 22Mvar (single 11Mvar) respectively; the sensitivity of the wind farm grid connection point voltage and wind turbine terminal voltage to the reactive power of wind turbines and wind farm SVG in the current mode is calculated, and the calculation 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 voltage optimization control model (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 controls the busbar, i.e. the target setting range of the grid connection point voltage It is 230~232kV.

[0214] Through the equivalent aggregation method, multiple wind turbines in each wind farm are equivalent to two wind turbines, and their initial reactive power is Q w1 , Q w2 , the wind farm SVG maintains the original number of sets, each wind farm has 2 sets of SVG, and 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 value of the wind farm grid connection point voltage are shown in Table 3:

[0219] Table 3

[0220]

[0221] In order to deal 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 by 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 s max They are 8Mvar, 8Mvar, 6Mvar (6.5Mvar rounded), and 3Mvar respectively. The initial single SVG reactive power of 13Mvar, 13Mvar, 12Mvar, and 11Mvar has exceeded the maximum value of SVG. Therefore, it is necessary to optimize the steady-state reactive power of the wind farm group, and re-optimize the distribution of wind farm reactive power between the wind farm SVG and wind turbines under the condition of minimum change in wind farm reactive power adjustment. At the same time, ensure that the SVG reactive power is evenly distributed between each set of SVG in the field, and the wind turbine reactive power is evenly distributed between each wind turbine in the field, so as to achieve the optimization goal of maintaining the voltage of the wind power grid connection point within the set range of 230-232kV.

[0222] The reactive power voltage optimization model (1) to (8) is 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: Fig.14 As shown in FIG. 1 , the wind farm group SVG reserves dynamic reactive power to cope with the large and rapid changes in the output of the wind farm group. Taking hlf as an example, the simulation curve of the rapid and large changes in the output of the wind farm is shown in FIG. Fig.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 terminal, grid-connected bus and main grid bus of the wind farm when the output of the wind farm group changes rapidly are as follows: Fig.16As shown in the figure, when the wind farm group output changes rapidly, the simulation results of the dynamic reactive power output of the wind farm group SVG are as follows: Fig.17 shown.

[0229] From the above simulation result curve, it can be seen 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 of 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 of 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), and tracks the voltage change through the wind farm group SVG constant voltage response control to automatically output reactive power to maintain the fluctuation of the voltage at the wind farm grid connection point and the terminal under the substantial and rapid increase in the output of the wind farm group. From the above bus voltage simulation results, it can be seen that when the wind farm has sufficient reactive power, the automatic output of the dynamic reactive power reserved by the SVG can smooth the voltage fluctuation under the rapid and substantial change of wind power output, and maintain the voltage in a basically unchanged range, which effectively prevents and controls the action of wind power fault ride-through.

[0230] Embodiment 2:

[0231] The present invention also proposes a fault ride-through prevention and control system 200 for wind power output with large and rapid fluctuations, such as Fig.18 As shown, including:

[0232] Initial 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 fixed-period steady-state reactive voltage control and the wind farm group 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 the 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 fault ride-through action 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 action under the large and rapid fluctuation of wind power output.

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

[0236] Among them, 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, including:

[0237] According to the wind conditions, unit types and internal wiring forms in the wind farm, multiple wind turbines in the wind farm are aggregated to generate equivalent aggregation models of the wind farm in steady state and transient state;

[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 that is close to the wind farm in electrical distance 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 adopting 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.

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

[0241] According to the data file, determine the basic output of the wind farm group Wind conditions and historical output of wind farm groups;

[0242] 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;

[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 wind farm groups 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 unit 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] Among them, 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 threshold value and duration of the action voltage are given for each discrete point, and multiple discrete points and the corresponding threshold value and duration of the action voltage are filled into the high / low voltage fault ride-through protection model of the wind turbine;

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

[0252] The simulation curves include: wind turbine terminal voltage simulation curve, wind turbine active power and reactive power simulation curve, grid-connected point bus voltage simulation curve, and grid-connected 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 wind turbines.

[0254] According to the simulation analysis results, it is determined whether the wind turbines in the wind farm group have a fault ride-through action. If so, the wind farm group is controlled in the reactive voltage control mode to prevent and control the fault ride-through action under the large and rapid fluctuation of 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 set according to the reactive voltage control mode. Update the SVG reactive power upper limit, and based on the updated SVG reactive power upper limit, perform wind farm group output according to a fixed control cycle under the reactive power voltage control model. The steady-state reactive voltage control model 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 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 power margin is 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 power upper limit, and based on the updated SVG reactive power upper limit, perform wind farm group output according to a fixed control cycle under the reactive power voltage control model. The steady-state reactive voltage control model 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.

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

[0258] Embodiment 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 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, and is specifically suitable for loading and executing one or more instructions in the computer storage medium to implement the corresponding method flow or corresponding functions, so as to implement the steps of the method in the above embodiment.

[0260] Embodiment 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 is understandable that the computer-readable storage medium here can include both a built-in storage medium in a computer device and an extended storage medium supported by the computer device. The computer-readable storage medium provides a storage space, which stores the operating system of the terminal. In addition, one or more instructions suitable for being loaded and executed by a processor are also stored in the storage space, and 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 appreciated by those skilled in the art that 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. Moreover, 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 codes. The schemes in the embodiments of the present invention may be implemented in various computer languages, for example, object-oriented programming language Java and literal scripting language JavaScript, etc.

[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 flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, 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 flowchart and / or block diagram. 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 capable of directing a computer or other programmable data processing device to operate 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 A 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 operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process in the computer or other programmable device. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0266] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other 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 can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

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-connected model for a group of wind farms, and generating a data file for simulation calculation based on the grid-connected model; Establish a reactive voltage control mode that coordinates the fixed-period steady-state reactive voltage control of the wind farm group and the SVG equipment-level constant voltage response control of the wind farm group; According to the data file, dynamically simulate the rapid and large-scale change characteristics of the wind farm group output, and obtain simulation analysis results that have a dynamic impact on the wind power grid connection point and the wind turbine terminal voltage; According to the simulation analysis results, it is determined whether the wind turbines in the wind farm group have fault ride-through action. If so, the wind farm group is controlled in the reactive voltage control mode to prevent and control the fault ride-through action under the large and rapid fluctuation of wind power output.

2. The method according to claim 1, characterized in that The establishment of a wind farm group access to the power 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 establishing of the steady-state and transient equivalent aggregation models of the wind farm, and establishing the steady-state model and 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, includes: According to the wind conditions, unit types and internal wiring forms in the wind farm, multiple wind turbines in the wind farm are aggregated to generate equivalent aggregation models of the wind farm in steady state and transient state; 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 that is close to the wind farm in electrical distance 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, characterized in that: The reactive voltage control mode includes: reserving a 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 turbine.

5. The method according to claim 1, characterized in that: The method of dynamically simulating the rapid and large-scale change characteristics of the wind farm group output according to the data file includes: According to the data file, determine the basic output of the wind farm group Wind conditions and historical output of wind farm groups; 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; Dynamically simulate the rapid and drastic changes in wind farm output.

6. The method according to claim 1, characterized in that 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 wind farm groups 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 unit 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 state includes reactive voltage and active phase angle.

9. The method according to claim 7, characterized in that: The simulation determines the rapid and large-scale change characteristics of the wind farm group output, and the dynamic impact of the voltage fluctuations 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.

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 threshold and duration of the action voltage are given for each discrete point, and multiple discrete points and the corresponding threshold and duration of the action voltage are filled into the high / low voltage fault ride-through protection model of the wind turbine; Simulation is performed through 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, characterized in that According to the simulation analysis results, determining whether the wind turbines in the wind farm group have a fault ride-through action, 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 large and rapid fluctuation of 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 set according to the reactive voltage control mode. Update the SVG reactive power upper limit, and based on the updated SVG reactive power upper limit, perform wind farm group output according to a fixed control cycle under the reactive power voltage control model. The steady-state reactive voltage control model 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 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 a fault ride-through action. If not, the SVG dynamic reactive power margin is set to is 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 power upper limit, and based on the updated SVG reactive power upper limit, perform wind farm group output according to a fixed control cycle under the reactive power voltage control model. The steady-state reactive voltage control model 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.

15. A fault ride-through prevention and control system for wind power output with large and rapid fluctuations, characterized in that: include: An initialization unit, used to establish a grid access model for a wind farm group, and to 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 and the SVG equipment-level constant voltage response control of the wind farm group; A simulation unit, for dynamically simulating the rapid and large-scale change characteristics of the wind farm group output according to the data file, and obtaining 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 fault ride-through action 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 action under the condition of large and rapid fluctuations in wind power output.

16. The system according to claim 15, characterized in that The establishment of a wind farm group access to the power 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, characterized in that The establishing of the steady-state and transient equivalent aggregation models of the wind farm, and establishing the steady-state model and 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, includes: According to the wind conditions, unit types and internal wiring forms in the wind farm, multiple wind turbines in the wind farm are aggregated to generate equivalent aggregation models of the wind farm in steady state and transient state; 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 that is close to the wind farm in electrical distance 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, characterized in that The reactive voltage control mode includes: reserving a 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 turbine.

19. The system according to claim 15, characterized in that The method of dynamically simulating the rapid and large-scale change characteristics of the wind farm group output according to the data file includes: According to the data file, determine the basic output of the wind farm group Wind conditions and historical output of wind farm groups; 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; Dynamically simulate the rapid and drastic changes in wind farm output.

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

21. The system according to claim 15, 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 wind farm groups 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 unit 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, characterized in that The operating state includes reactive voltage and active phase angle.

23. The system according to claim 21, characterized in that The simulation determines the rapid and large-scale change characteristics of the wind farm group output, and the dynamic impact of the voltage fluctuations 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.

24. The system according to claim 21, characterized in that 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 threshold and duration of the action voltage are given for each discrete point, and multiple discrete points and the corresponding threshold and duration of the action voltage are filled into the high / low voltage fault ride-through protection model of the wind turbine; Simulation is performed through the high / low voltage fault ride-through control and protection model of wind turbines.

25. The system according to claim 21, 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.

26. The system according to claim 21, 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.

27. The system according to claim 21, characterized in that According to the simulation analysis results, determining whether the wind turbines in the wind farm group have a fault ride-through action, 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 large and rapid fluctuation of 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 set according to the reactive voltage control mode. Update the SVG reactive power upper limit, and based on the updated SVG reactive power upper limit, perform wind farm group output according to a fixed control cycle under the reactive power voltage control model. The steady-state reactive voltage control model 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 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, characterized in that According to the simulation analysis results, it is determined whether the wind turbines in the wind farm group have a fault ride-through action. If not, the SVG dynamic reactive power margin is set to is 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 power upper limit, and based on the updated SVG reactive power upper limit, perform wind farm group output according to a fixed control cycle under the reactive power voltage control model. The steady-state reactive voltage control model 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.

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.

Images