双馈感应风力发电系统低电压穿越控制策略研究及其分析

Low voltage ride through control strategy and its analysis of doubly fed induction generator

基于双馈感应发电机(DFIG)风力发电系统模型,通过分析电网电压跌落情况下的各种运行状况,提出在电网严重故障期间,采用Active Crowbar电路和直流侧卸荷电路保护变流器和避免直流侧电压过压。在电网故障恢复期间,Crowbar电路的再次投入使得系统无功需求增大。并在网侧变流器的功率容量范围内,提出一种网侧变流器无功功率的控制策略来实现对电网无功支持,以助于电网故障恢复以及加快机端电压恢复。基于PSCAD/EMTDC平台建立了仿真系统模型并验证了该控制策略的有效性。该控制策略满足了风电机组并网的低电压穿越,有效提高了DFIG风电机组运行的可靠性。

Based on double fed induction generator （DFIG） wind power system model, by analyzing the grid voltage drop under various operational performance, this paper proposes the use of Active Crowbar Circuit and DC-chopper in order to protect the converter and avoid DC-link over-voltages during grid serious faults. Crowbar circuit being into again makes the demand of the reactive power increase during the recovery of the grid voltage; grid-side converter （GSC） in the range of power capacity, a new control strategy for GSC reactive power is proposed to achieve the reactive power support to help the recovery of the grid faults and the stator voltage. Simulation system model is built by using PSCAD/EMTDC and the validity of the proposed control strategy is proved. The control strategy meets low voltage ride through （LVRT） of DFIG, and effectively improves the reliability of the DFIG operation.