Research On The Reactive Power Optimization Control Strategy Of AVC In DFIG-based Wind Farms Based On DIgSILENT

The current world energy crisis and environmental deterioration, scholars from various countries committed to finding clean energy, which gives wind and solar and other renewable energy sources an opportunity to rapidly develop. In particular, wind energy is abundant, have high available rate and costs the same with traditional energy generation. Wind power network capacity is increased year by year. But wind power is volatile and intermittent, which leads to the voltage stability of power systems. The study of wind farm grid automatic voltage control is particularly important. Currently, the installation of reactive power compensation equipment is one of the primary means of improving the voltage stability of grid containing the wind farm. But with the amount of reactive power compensation devices increases, decentralized independent control strategy has been unable to meet the dynamic coordination of grid voltage control needs. So the study of control strategy to optimize the wind farm AVC system is necessary.Firstly, the paper starts with the basic unit of the wind power generation system-wind turbines, establishes a model of mainstream models that doubly fed induction wind turbines and analyzes the decoupled control principle of RSC and GSC. Doubly-fed induction wind turbine model is built in DIgSILENT. Secondly, paper analyzes the reactive power limit of DFIG-based wind farms, which provides technical support for further study of wind farm AVC strategy.Aiming at the wind farm consists of double-fed wind turbines and SVG, a simplified AVC strategy is proposed that is based on seven-zone diagram and also use graded regulator principle, in order to realize voltage stability of each node in the wind farms.Finally, build a simulation model of a wind farm in northern Hebei Province on DIgSILENT simulation platform and use the control strategy to dynamically regulate the reactive power output of SVG and DFIG Simulation examples show that the control strategy can maintain the wind farm PCC voltage stability and also improve stability margin of the voltage.