考虑不同转差的双馈风力发电机短路计算序分量模型

Sequence Component Models for Short-circuit Calculation of DFIG with Different Slips

双馈风力发电机(doubly fed induction generator,DFIG)大规模接入电网对短路电流的影响逐渐显现。常规的短路计算中,将DFIG忽略或作为负荷的方式会对短路计算的结果产生较大误差。为此通过分析DFIG短路计算模型的外特性,提出求解短路计算模型的方法;利用DFIG的数学模型,推导电网电压跌落下DFIG短路电流的解析表达式;根据不同的转差,提出相应的DFIG短路计算序分量模型。分析的结果表明:转差较大的DFIG可等效为一恒定阻抗负荷,而转差较小的DFIG则应等效为一同步电机,会给电网注入短路电流。最后通过MATLAB/Simulink仿真,验证了这种基于不同转差的DFIG短路计算序分量模型能保证短路计算的精确性。

Effect of large-scale accessing of the double fed induction generator （DFIG） into the power grid on short-circuit current is gradually appearing. In conventional short-circuit calculation, it may cause great errors due to neglecting DFIG or taking DFIG as load. Thus, this paper analyzes the external characteristic of the DFIG short-circuit calculation model and presents a kind of method for solving the model. By using the DFIG mathematical model, it deduces the analytic expression of DFIG at the time of voltage sag, and according to different slips, it proposes relevant sequence component models for DFIG short-circuit calculation. The analysis results indicate as slips are large, the DFIG could be equivalent to constant im- pedance load while as slips are small, the DFIG should be equivalent to a synchronous generator which could inject short-cir- cuit current into the power grid. MATEAB/SImulink simulation has verified this sequence component model for DFIG short- circuit calculation based on different slips can ensure accuracy of short-circuit calculation.