双馈风机风电场联络线出口故障方向判别

由于双馈风机风电场故障特性与传统同步机存在较大差别,因此传统方向元件应用于双馈风机风电场时存在适应性问题。针对双馈风机风电场存在的频率偏移、等值内阻抗不稳定和弱馈等特点,提出一种基于时域波形相似度的故障方向元件。根据推算的联络线对侧电压与保护安装处记忆电压波形的余弦相似度判断故障方向,能够有效解决双馈风机风电场出口故障方向判别存在的问题。在PSCAD/EMTDC中搭建典型的双馈风机接入系统,仿真结果表明,所提故障方向元件针对不同的故障类型均能有效判断故障方向。

Fault Direction Identification for Outgoing Line of DFIG-based Wind Farm

Due to the substantial difference between the fault characteristics of a doubly-fed induction generator(DFIG)-based wind farm and those of a conventional synchronous generator(SG),the traditional directional element fails to provide the correct fault direction when it is applied to the DFIG-based wind farm.Considering the characteris?tics such as frequency deviation,unstable equivalent internal impedance,and weak feed,a solution based on wave?form similarity in time domain is proposed.According to the cosine similarity between the opposite-side voltage of the transmission line and the waveform of memory voltage at the protection site,the problem with the fault direction identifi?cation for the outgoing line of the DFIG-based wind farm can be effectively solved.A typical DFIG-based system is built in PSCAD/EMTDC,and simulation results show that the proposed fault directional element can effectively identify the fault direction under different types of fault.