考虑低电压穿越影响的双馈感应发电机谐波电流特性

摘要

Double fed induction generator (DFIG) is the most widely used wind generator. Because of its special struc-tural design the operating characteristic of DFIG becomes much complicated during fault,especially under the low voltage ride through,and the output of DFIG has caused a series of effects on the safe operation of power grid and relay protection. At present a lot of research has focused on the short-current characteristic of DFIG,but the study of the harmonic current is rarely reported. This paper studies on the stator harmonic current and rotor harmonic current of DFIG during asymmetric fault with consideration of the effect of LVRT. From the perspective of electromagnetic transients,the analytic expressions of the DFIG stator harmonic current are derived in detail under the condition of Crowbar action. The generation mechanism of the harmonic current on the stator and rotor of DFIG caused by the converter control is researched under the condition of the crow-bar inaction. The conclusion made is verified by simulation.%双馈感应发电机（DFIG）作为当前应用最广泛的风力发电机，其特殊的结构使其故障运行特性十分复杂，尤其在低电压穿越（LVRT）运行状态下，已对电网安全运行和保护控制的顺利实施造成一系列影响。目前对DFIG的短路电流特性已有大量研究，但是针对定转子电流谐波特性的研究还鲜有报道。考虑LVRT的影响，对电网不对称故障情况下DFIG定、转子谐波电流的特性进行研究。从电磁暂态过程的角度详细推导了Crowbar动作后的DFIG定子谐波电流的解析表达式；在Crowbar未动作时，从转子侧变流器影响机理出发，研究了由变流器控制引起的定、转子谐波电流的产生机理。所得结论通过仿真进行了验证。