电网故障下计及撬棒保护的双馈感应发电机暂态解析修正模型

Corrected Transient Analysis Model of Doubly Fed Induction Generator With Crowbar Protection Under Grid Fault

建立双馈感应发电机(doubly-fed induction generator,DFIG)在电网故障时的暂态解析模型是分析风电机组低电压穿越(low voltage ride through,LVRT)能力的基础,也是提高电力系统故障计算效率的有效手段。传统解析模型中忽略了定、转子磁链间的耦合,对撬棒保护接入后DFIG的暂态理论分析带来较大的误差。该文提出了一种电网故障下计及撬棒保护的DFIG暂态解析修正模型。从DFIG的空间矢量数学模型出发,通过状态方程的特征根定义了反映定、转子磁链耦合的修正系数;利用修正系数分析了Crowbar电阻对DFIG暂态特性的影响;求解状态方程得到了DFIG暂态解析修正模型。仿真验证了修正系数分析的正确性和暂态解析模型的准确性。

Establishment of the transient analytic model of doubly-fed induction generator （DFIG） in power grid under fault occurrence is the basis of analyzing the low voltage ride through （LVRT） capability of wind turbines, and also is an effective way to improve the efficiency of power system fault calculation. Traditional analytic model usually ignores the magnetic coupling between stator and rotor, which brings errors to the DFIG transient model when bypass resistors are connected to protect the converter. A correction model for transient analysis of doubly-fed induction generator with crowbar protection under fault was presented. Based on the space vector model of DFIC, the correction factor was defined for the magnetic coupling between stator and rotor by characteristic roots of state-space equation. The influence of crowbar protection on the transient characteristics of DFIG was analyzed by using the correction factor. Transient analysis modified model of DFIG was derived by solving the statespace equation. The simulation results verify the correctness of the correction factor and the accuracy of the correction transient analysis model.