计及阻容式撬棒动作时间的双馈风机短路电流分析

Short Circuit Current Analysis of DFIG Considering Resistance-Capacitance Type Crowbar Protection Action Time

首先从机理和磁链角度出发,分析机端电压跌落时双馈式感应发电机短路电流特性。在此基础上,研究电阻串联电容的阻容式撬棒电路对短路电流的影响,并综合考虑撬棒动作时间,将故障过程分为两个阶段。以转子暂态磁链作为连接两个阶段的纽带,对计及阻容式撬棒投入时间的定转子短路电流解析式进行推导,结合解析式并从消除转子短路电流暂态直流分量角度考虑推出电容的表达式。最后,在Matlab/Simulink平台上搭建1.5MW双馈风机动态模型,对短路电流解析式的正确性以及阻容式撬棒在抑制转子浪涌电流、改善无功功率吸收、滤除转子侧故障电流直流分量等方面的有效性进行验证。

Firstly,from the perspective of mechanism and flux linkage,the short-circuit current characteristics of the doubly-fed induction generator(DFIG)when the voltage drops are analyzed.On this basis,the influence of the resistance-capacitance crowbar circuit with resistors and capacitors in series on the short-circuit current is studied,and the action time of the crowbar is comprehensively considered,the fault process is divided into two stages,and the rotor transient flux linkage is used as the connection stage.The analytic formula of the stator and rotor short-circuit current considering the action time of the resistance-capacitance crowbar is derived,combined with the analytic formula,and the capacitance value expression is derived from the perspective of eliminating the transient DC component of the rotor short-circuit current.Finally,a dynamic model of 1.5MW DFIG is built on Matlab/Simulink platform to verify the correctness of short-circuit current analytical formula and the effectiveness of resistance-capacitance crowbar in suppressing rotor surge current,improving reactive power absorption and filtering DC component of rotor side fault current.