双馈风力发电机低电压过渡的相角补偿控制策略

基于撬棒保护(crowbar)的控制方法是双馈风电机组(doubly-fed induction generator，DFIG)实现低电压过渡(low voltage ride through，LVRT)的主要方式之一。在撬棒保护退出后，故障恢复过渡过程中，转子过电流仍有可能损坏变流器。针对上述问题，通过双馈电机的动态等效模型构建故障过程系统分析模型，深入分析故障发生和电网电压恢复过程中的机端电压相角跳变机制及其对矢量定向精度的影响。在此基础上，提出相角补偿控制原理，改进现有 LVRT控制策略，将控制流程分为正常运行、撬棒保护投入、撬棒保护退出和电网电压恢复4个阶段。在正常运行及撬棒保护退出阶段，采用定子磁链定向控制；在撬棒保护投入阶段，封闭转子侧变流器绝缘栅双极型功率管(insulated gate bipolar transistor，IGBT)的脉冲，网侧变流器保持正常工作；在电网电压恢复阶段采用相角补偿控制。仿真结果表明，所提控制策略能够有效抑制电网电压恢复过程中的过电流。

Phase Angle Compensation Control Strategy for Low-voltage Ride Through ofDoubly-fed Induction Generator

The crowbar-based control is one of the main low-voltage ride through (LVRT) control methods for doubly-fed induction generators (DFIG), but the converter is still at risk of being damaged by the over-current on the rotor side after the crowbar exits during the fault recovery period. To solve such issues, a model for the fault process analysis based on the equivalent dynamic model of DFIG is established. The mechanism of the phase angle jumping when a fault occurs and the grid voltage recovers and its impact on the vector orientated precision are analyzed. Based on this, the jumping phase angle compensation principle is proposed to improve the existing LVRT control strategy. Then the process of control is divided into four periods, i.e., the normal operation period, the crowbar switching period, the crowbar exiting period and the grid voltage recovering period. In the normal operation and the crowbar exiting period, the stator flux orientation control of DFIG is applied. In the crowbar switching period, IGBT pulses of the rotor side converter are locked, but the grid-side converter maintains the normal operation. In the grid voltage recovering period, phase angle compensation control is used. Simulation results show that the over-current in the grid voltage recovering period can be effectively limited by the proposed control strategy.