考虑Crowbar动作特性的DFIG风电场动态等值研究

Dynamic Equivalence of Wind Farm Composed of Double Fed Induction Generators Considering Operation Characteristic of Crowbar

加装Crowbar电路是双馈感应风力发电机实现低电压穿越的常用措施。为考虑低电压穿越对风电场动态等值的影响,首先分析了Crowbar的动作特性,对比了两种常用投切策略对电网稳定性的影响,以及同种投切策略下Crowbar不同退出时间对风电场出口处动态特性的影响。然后研究了风电机组不同运行状态对Crowbar启动时间的影响。仿真结果表明,凡是Crowbar发生动作的机组,在机电暂态仿真步长下其Crowbar启动时间几乎是一致的。在此基础上,提出了基于Crowbar动作区域曲线判断Crowbar动作情况,并以Crowbar是否动作作为分群准则的风电场分群等值方法。最后在DigS ILENT平台上搭建算例,验证了等值方案的有效性。

The crowbar circuit is commonly applied in doubly fed induction generators （DFIG） to implement the low voltage ride through （LVRT）. To consider the impact on LVRT on dynamic equivalence of wind farm, firstly the operation characteristic of crowbar circuit is analyzed and the impacts of two kinds of commonly used switching on/off strategies for the crowbar circuit on power grid stability are compared, and the impacts of different quit time of crowbar circuit under the same switching strategy on the dynamic characteristics at the outlet of wind farm are researched. Secondly, the impacts of different wind farm operation conditions on the starting time of the crowbar circuit are researched. Simulation results show that the crowbar circuit starting times of all DFIG sets, where the action of crowbar circuit occurs, are almost coincident under electromechanical transient simulation step. On this basis, an equivalent clustering method for wind farm, which judges the action situation of crowbar circuits according to their action area curves and takes whether the crowbar circuits acts or not as the criterion of the clustering, is proposed. Finally, a calculation case is constructed on DigSILENT platform and the simulation results show that the proposed equivalent scheme is effective.