双馈风力发电机组无功调节机理及无功控制策略

The Reactive Power Adjusting Mechanism & Control Strategy of Doubly Fed Induction Generator

以双馈感应发电机组(doubly fed induction generator,DFIG)等效电路为基础,分析DFIG定子和网侧换流器的无功调节机理。对比两者动态过程和稳态效果,确定两者无功调用的优先级,并根据两者无功调节能力制定DFIG的无功控制策略。当无功需求大于DFIG无功出力极限时,通过减小有功出力来扩大DFIG无功出力范围,并采用基于无功缺额的定子有功功率附加控制器,以机组无功出力极限与电网需求相等和机组出力最大为控制目标,最小限度地降低机组出力,提高机组的无功出力极限。基于PSCAD/EMTDC的数字仿真结果验证了理论分析和控制策略的正确性。

Based on the equivalence circuit of a doubly fed induction generator （DFIG）, the paper analyzed the reactive power adjusting mechanism of the stator and the grid side converter. Contrasting the dynamic with steady state, the reactive power adjusting priority between the stator and the grid side converter was decided. Based on the analysis of reactive power limits, the reactive power control strategy was presented. When the grid reactive need exceeds the ultimate reactive capacity of DFIG, it is used to diminish the active power of DFIG for enlarging the ultimate reactive capacity. The additional control of stator active power based on the reactive power vacancy was also presented, in which the control aim is to find out the minimal active power reduction to expand the reactive power limits of DFIG, and the reactive limits equal to the grid reactive power needed in the final. The simulations performed in PSCAD/EMTDC to verify the theoretical analysis and the reactive power control strategy.