Research On Coordinated Control Of Reactive Power In Large Scale Wind Farm Groups

According to the policy of China’s12th Five-Year Plan, energy industry shall be reformed by developing safe, economical and clean new energies. Wind power, as the most mature one in new energy industry, has been enjoying a booming in China. However, the transmission distance to the load center is long since the distribution of wind resources are more concentrated in the terminal of the grid in China. Wind turbine, as a kind of asynchronous generator, has to consume reactive power while generating active power, therefore the reactive voltage becomes a primary issue when several wind farms constitute a large-scale wind power base and access to the grid.The thesis takes the basic unit of wind power system-wind turbines as the object of research and develops a mathematical model of mainstream double-fed wind turbines. Based on the model, the reactive power capacity of double-fed wind turbines is analyzed, laying a foundation for the optimization of reactive power of large-scale wind power bases.The thesis proposes a reactive voltage control strategy for wind farms containing SVC and composed of double-fed wind turbines. Through the cooperation of double-fed wind turbine and SVC, the voltage at point of common coupling (PCC) can track the target voltage automatically. In this way, the reactive power in wind farms is optimized and the reactive power equipment is fully utilized to achieve the stability of nodal voltage in wind farms. The strategy is applied to CSC-800W wind power control system of Beijing Sifang Automation Co.,Ltd. and verified through simulation.Besides, a regional coordinated control strategy is presented for large-scale wind power groups. The strategy, by controlling tracking and dispatching instruction of busbar voltage collected from substations by wind farms and coordinating reactive power of each wind farm, stabilizes the voltage of each wind farm in the region and optimizes the reactive power of the large-scale wind power base. Moreover, a coordinated control system of reactive voltage is developed for wind farm cluster based on the strategy. It is proved by the case of large-scale wind power base in Tongyu, Jilin that the system can help the master station control the reactive power in large-scale wind power bases.