双馈风电场群短路电流计算与故障分析方法

Short circuit current calculation and fault analysis method of DFIG wind-farm groups

由于风电场群内各风电场的暂态特性存在较大差异,且各风电场及系统间存在较强的耦合关系,这些因素增加了风电场群接入后电力系统故障分析的复杂度。基于变流器的输入-输出外特性等值了变流器的数学模型,进一步给出了计及变流器控制影响的双馈风电机组暂态模型,分析了低电压穿越控制策略对短路电流的影响机理,并建立了双馈风电机组的短路电流计算模型。分析了故障期间风电场间的相互影响机理,提出了双馈风电场群的短路电流计算方法。采用RTDS建立含双馈风电机组实际控制器的物理实验平台,验证了所提出的双馈风电场群短路电流计算方法的准确性。在此基础上对双馈风电场群接入后的电网故障分析方法进行了探讨与分析。

The transient characteristics of different wind farms in wind-farm groups are quite different and the coupling relation between each wind farm and grid is quite strong,which make the failure analysis of the grid with wind-farm groups more complicate. An equivalent inverter model is established based on the external characteristics of its inputs and outputs,a DFIG transient model considering the influence of inverter control is provided,the influence of LVRT control strategy on the short circuit current is analyzed, and a short circuit current calculation model of DFIG wind unit is built. The interaction among wind farms during a fault is analyzed and a method for calculating the short circuit current of DFIG wind-farm groups is proposed. A physical experimental platform with DFIG wind unit controller is established based on RTDS to verify the correctness of the proposed short circuit current calculation method. The fault analysis method of the grid with DFIG wind-farm groups is discussed and analyzed.