Research On Coordinated Control Of Reactive Power And Voltage In Power Grid Considering Wind Power Regulation Capability

The use of wind energy is one of the effective means to solve the serious problem of energy shortage and environmental degradation,and wind power generation technology is becoming more and more mature.However,with the continuous expansion of the scale of wind farms and the significant increase of the proportion of wind power in the power generation structure,the reactive power and voltage problems caused by the instability and fluctuation of wind energy have become increasingly prominent,which has attracted the attention of all countries in the world.The large-scale development of wind power cluster and long-distance centralized transmission in China make this problem more serious.In order to solve this problem effectively,this thesis focuses on the coordinated control strategy of reactive power and voltage in the power grid considering the wind power regulation capability,so as to give full play to the reactive power support capability of wind farms,make it work in coordination with dynamic reactive power compensation device to improve the system voltage balance.Firstly,based on the working principle and mathematical model of direct-drive permanent magnet synchronous generator(PMSG)and doubly-fed induction generator(DFIG),the analytical expressions of the reactive power limit of PMSG and DFIG are given.Then the reactive power limit diagram of typical units is drawn in PSASP platform.The results indicate that the theoretical calculation value of the reactive power limit of PMSG is consistent with the simulation results,while the theoretical calculation value of the reactive power limit of DFIG deviates greatly from the simulation results.In view of this problem,the input parameter of simulation model in PSASP is optimized,which makes the theoretical calculation value and simulation results of reactive power limit of DFIG match well.It verifies the accuracy of the calculation formula and provides a theoretical basis for the formulation of reactive power control strategy of wind farm s.Secondly,the principle of reactive power compensation devices for different types and capacities of wind farms is described,the simulation model of static var generator(SVG)in typical wind farms is established,and the influence of SVG capacity and controller parameters on its response characteristics is analyzed.According to the analysis of SVG response characteristics,the relevant control parameters and capacity of SVG are determined.Then the basic functions of constant voltage control and constant reactive power control,as well as voltage characteristics and dynamic response characteristics are verified.The simulation results prove that the functions and characteristics can meet the requirements of relevant standards.Finally,a reactive power and voltage control strategy based on sensitivity method is proposed,a mathematical model of reactive power and voltage coordination optimization of wind farms is established,and particle swarm optimization(PSO)algorithm is applied to solve the corresponding optimization problem.The strategy is beneficial to reduce the search space and improve the calculation efficiency.The simulation results demonstrate that the proposed reactive power and voltage control strategy can make the voltage meet the control objectives,reduce the network loss of wind farm group system,which is conducive to improve the voltage regulation level and economic benefits in the wind power grid connected area.