Research On Control Strategy Of Wind Farm Voltage Support Based On SVG And DFIG

In recent years,with the gradual increase of the penetration rate of wind power generation,the problem of reactive voltage caused by grid connection of wind power has seriously affected the safe and stable operation of the power grid,and researchers have gradually paid attention to the reactive power adjustment capability of wind turbines.When traditionally dealing with the problem of reactive voltage caused by grid connection of wind power,it relies too much on reactive power compensation devices.At present,most of China’s wind power bases are concentrated in the relatively underdeveloped northwestern region of China,and excessive reliance on dynamic reactive power compensation devices to solve reactive voltage problems has increased the construction cost of wind farms.This paper considers the combined use of Doubly Fed Induction Generator(DFIG)and Static Var Generator(SVG)to participate in the voltage regulation of wind power systemsThis article analyzes and introduces the mathematical model of each component of DFIG,the internal power flow,and the control strategies of the control system.Then through the analysis of the DFIG rotor side under the grid side voltage fault,and the analysis of the DFIG’s reactive power regulation capability under the grid side normal working conditions and the low voltage caused by the fault,it was found that the grid side fault caused the voltage to be too low The existing rotor-side control strategy has some shortcomings in supporting the voltageThe dissertation designs an improved control scheme for the shortcomings of the existing rotor-side control strategies.An adaptive power limiting factor control strategy is further proposed.Based on the Matlab/Simulink platform,a simulation case model of a single wind farm system was built,and the improvement scheme and power factor control strategy were simulated and verified.The simulation results prove that when the grid side fault causes the voltage to be too low,under the original control strategy,DFIG’s reactive power adjustment capability will be affected.DFIG may completely lose its reactive power adjustment capability when the voltage drops severely.The improved rotor side control scheme can help DFIG maintain the reactive power adjustment capability before the fault as much as possible.With the help of the adaptive power-limiting factor control strategy,as long as the DFIG works stably,it assists the restoration of the grid voltage as much as possible.The simulation results show that when the grid-side working conditions are normal,DFIG’s own reactive power adjustment capability alone can meet the needs of normal operation of the wind farmFinally,the working principle and control method of SVG are introduced,and the reactive power loss in a doubly-fed wind farm is analyzed in detail.A control scheme of SVG and DFIG to assist system voltage regulation is designed.Then,the collaborative control strategy is verified through simulation.The simulation results prove that the SVG and DFIG proposed in this paper have a good effect on system voltage regulation.When there is a reactive power shortage in the grid-side system,DFIG first operates,and the DFIG power factor reaches±0.95.After fully utilizing the DFIG’s reactive power adjustment capability,if the voltage does not recover,SVG is called to start work.This scheme proves that the use of DFIG’s reactive power adjustment capability can effectively reduce the capacity of the reactive power compensation device to be deployed in the wind farm,thereby effectively reducing the investment cost of the wind farm construction,and has important economic value for the construction of the wind farm.