Crowbar和Chopper保护对双馈风机低电压穿越的影响分析

Analysis on the Influence of Crowbar and Chopper Protection on Low Voltage Crossing of Doubly-fed Wind Generator

针对在电网低电压故障期间,双馈风力发电机因硬件保护出现离网问题,研究基于Crowbar阻值和增加Chopper保护电路对DFIG的影响。首先,在转子交流侧采用主动型Crowbar电路,可保护转子侧变流器减少暂态冲击电流的影响,直流侧配备卸荷(Chopper)电路,可在暂态过程中维持直流侧电压稳定;其次,在分析电网电压跌落过程中双馈风机的暂态特性基础上,采用基于定子电网电压定向的控制策略,合理的选取Crowbar阻值范围,并分析Crowbar和Chopper投切时刻对双馈风力发电机安全低穿的影响,在MATLAB/Simulink仿真平台中建立1.5 MW双馈风力发电机组模型,验证了Crowbar和Chopper保护电路的有效性。

To address the off-grid problem of the doubly-fed induction generator due to the hardware protection during the low voltage failure of the power grid,the influence of Crowbar resistance value and Chopper circuit protection on doubly-fed induction generator is studied.First,the active Crowbar circuit is adopted on the AC side to protect the rotor-side converter from the impact of transient impulse current,and the DC side is equipped with a chopper circuit to maintain the DC-side voltage stability during the transient process.Secondly,based on the analysis of the transient characteristics of the doubly-fed fan in the grid voltage sagging process,the control strategy for the stator grid voltage orientation is adopted to select the reasonable Crowbar resistance value range and analyze the influen ce of Crowbar and Chopper switching time on doubly-fed induction generator safe low penetration.A 1.5 MW doubly-fed wind generator set model was established in MATLAB/Simulink for verification of the validity of Crowbar and Chopper protection circuit.