Reactive Power Optimization Control Of Wind Farm With Front-end Speed Controlled Wind Turbine

With the increase of energy consumption in the world,the utilization of wind energy is becoming more mature,and wind power technology is developing rapidly.The front-end speed controlled wind turbine is a new type of generating unit,which has the advantages of reactive power output,low voltage ride through and good power quality.However,the research on reactive power optimization of wind farms with front-end speed controlled wind turbines is still lacking.With the increase of the capacity of the wind turbine assembly,the self reactive power regulation ability of the wind farm is greatly challenged,which requires front-end speed controlled wind turbines with strong reactive power output to participate in the reactive power optimization control of the wind farm.The research on reactive power optimization control of wind farm with front-end speed controlled wind turbines is of great significance for the promotion of the unit in China and for the development of wind power technology in China.In order to obtain the reactive output range of the speed controlled wind turbine,the theory of operation of the front-end speed controlled wind turbine is analyzed in this thesis,and establishes the wind turbine model,transmission chain model,excitation system model,and synchronous generator model of the front-end speed controlled wind turbine.The mathematical model and output power equation of the front-end speed controlled wind turbine are obtained.Combined with the reactive power constraints of the synchronous generator,the reactive output range of the front-end speed controlled wind turbine is analyzed and a robust excitation controller is designed to control the reactive power of turbines.The structure and operating principle of mainstream reactive power compensation devices for wind farms are analyzed,and reactive power compensation devices are selected through simulation and comprehensive comparison.In order to improve the distribution of reactive power flow in wind farms and reduce network loss in the field,with the objective of minimizing the active energy loss and the annual cost of compensation devices,the voltage is used as a constraint,and an improved Genetic Algorithm(GA)is applied to wind farms.After optimization of reactive power planning,the optimized installation position of reactive power compensation and the reactive power capacity of the compensation device were first established.Based on this,a reactive power stratified hierarchical control strategy for wind farms is proposed,and the reactive power output capacity of the front speed controlled wind turbines or reactive compensation devices are allocated by the optimization results in each scene,and the reactive power output of the units and the reactive compensation devices are controlled to achieve the bottom control of reactive power.Through the reactive power optimization control of wind farms,the economic and voltage stability of wind farms can be achieved.