Area Automatic Voltage Control of Large-Scale Wind Farms

In recent years, wind power in China is developing rapidly, with specific characteristics of large- scale, high concentration and remote distance. With large scale wind farms integrated into grid, the voltage and reactive power problem is worth concentrating on. Based on this situation, a strategy of area automatic voltage control (Area- AVC) is proposed to solve it. AVC is divided into three hierarchies: system-wide control, wind farm level control, wind turbines and equipment level control. System-wide control gives the reference voltage value of the pivot bus to the wind farm level control based on optimal power flow. Wind farm level control makes control strategies taking into account both the voltage difference and static voltage stability. Because of the contradiction of the multi-objective, non-domination sorting genetic algorithm (NSGA-II) is used to solve this problem. Wind turbines and reactive power equipment, as the bottom level, act according to the strategies of wind farm level. Finally, a case with typical topology of wind farms integrated into grid in China demonstrated its validity in insuring the security and economy.