对称故障且crowbar保护未动作情况下双馈感应发电机转子电流增量分析

定量分析双馈感应发电机在机端发生对称短路故障过程中转子电流增量特性,对风电场的规划设计、保护配置以及降低连锁脱网故障风险具有重要意义。以机端发生对称短路期间转子转速、初相以及定转子励磁电压恒定为研究条件,分析了crowbar保护（撬棒保护）未动作情况下双馈感应发电机的电磁暂态过程,并根据叠加原理,提出了机端发生对称短路故障下的转子电流增量最大值的计算方法,并且在忽略定子绕组和转子绕组的基础上,推导了机端电压增量与转子电流增量之间的解析计算模型。通过不同机型的风电机组的数值计算结果进行对比,解析计算模型的计算误差小于10%,验证了解析计算模型的有效性。

Rotor Current Increment Analysis of Doubly-Fed Induction Generator During Symmetrical Faults Before Crowbar Protection Trigger

It is important to analyze rotor current increment characteristics quantitatively for doubly-fed induction generators(DFIG) initiated by terminal voltage symmetrically dip for wind farm planning, relay protection configuration and cascading trip-off risk reduction. Under conditions of constant rotor speed, excitation voltage in early phase, the electromagnetic transient process of DFIG before crowbar protection triggered is analyzed in detail. By using superposition principle, a maximum rotor current increment calculation method for DFIG initiated by terminal voltage dip is proposed. Furthermore, analytic model to calculate maximum increment of rotor current for DFIG initiated by terminal voltage dip without consideration of stator and rotor winding resistance is derived. Calculating results of different kinds of generators are within 10% error margin compared with iterative calculation results, which show effectiveness of proposed analytical method.