基于无功判定法的Crowbar保护电路退出控制

Crowbar protection circuit quitting control based on the reactive power judgment

'并网难'已成为风电发展的瓶颈,而低电压穿越(Low Voltage Ride Through,LVRT)是风电并网中的核心技术,目前主要采用Crowbar保护电路实现风电机组在大干扰下也具有LVRT能力,而Crowbar电路退出时间对电网故障恢复有很大的影响。根据我国风电大规模远距离的特点,在DIgSILENT中建立了双馈风力发电机组(Doubly-Fed Induction Generator,DFIG)的动态模型,并经过远距离输电线与IEEE9节点电力系统相连,仿真分析了DFIG在各种短路故障条件下的运行特性,提出一种基于无功功率判定的Crowbar退出控制方法,能实现Crowbar电路在故障切除后立刻退出,提高了DFIG的LVRT能力。

＂Difficult grid-connection＂ has become the bottleneck of wind power generation development. And the low voltage ride through （LVRT） is the core technology of grid-connected wind power generation. At present the Crowbar protection circuit is mainly used to realize the LVRT capability of wind generator under large disturbances. And the quitting time of the Crowbar protection circuit has important effect on electric network fault restoration. According to the characteristics of large scale and long distance of China＇s wind power generation, in this paper, a dynamic model of doubly-fed induction generator （DFIG） which is connected with the IEEE9 nodes power system through the long distance transmission line has been established in DIgSILENT. The operational characteristics of DFIG under various short circuit fault conditions are simulated and analyzed. A Crowbar protection circuit quitting control method based on the reactive power judgment is presented, which can realize Crowbar protection circuit quitting immediately after fault clearance and can improve the LVRT capability of DFIG.