基于正序阻抗角的海上DFIG定子绕组匝间短路故障辨识

Inter-turn Short-circuit Fault Identification of Stator Winding for Offshore DFIG Based on Positive Sequence Impedance Angle

为了保证海上双馈风力发电系统的安全可靠运行,提高海上DFIG定子绕组匝间短路故障辨识的精准度,文中提出一种以定子侧正序阻抗角为故障特征量的定子绕组匝间短路故障辨识方法。由于故障后各序分量不再对称,首先基于DFIG定子匝间短路故障状态下的序分量模型,推导得出DFIG定子侧正序阻抗角的表达式;然后分析电网电压不平衡、负载和转差率变化等非理想工况对该故障特征的影响规律,提出合理的故障辨识阈值。仿真与实验结果表明,该故障特征对电网电压不平衡具有鲁棒性,且通过合理设置故障阈值可实现对海上DFIG定子绕组匝间短路故障的精确辨识。

In order to ensure the safe and reliable operation of offshore doubly-fed wind power generation system and improve the accuracy of inter-turn short-circuit fault identification of offshore doubly-fed induction generator(DFIG)stator winding,a stator inter-turn short-circuit fault identification method based on positive sequence impedance angle on stator side is proposed.Since the sequence components are no longer symmetrical after fault,the expression of positive sequence impedance angle of DFIG stator side is derived based on the sequence component model of DFIG stator inter-turn short-circuit fault.Then the influence of nonideal conditions such as unbalanced voltage,load and slip rate on the fault characteristics is analyzed,and a reasonable fault identification threshold is proposed.The simulation and experimental results show that the fault feature is robust to the unbalanced voltage of power grid,and the accurate identification of DFIG stator winding inter-turn short-circuit fault can be achieved by setting the fault threshold reasonably.