基于电压相量的直驱风电场联络线单相自适应接地距离保护

Single-Phase Adaptive Grounding Distance Protection for Tie Line of PMSG Wind Farm Based on Voltage Phasors

针对过渡电阻造成阻抗测量不准确引起风电场联络线单相接地距离保护拒动或超越的问题,分析了双电源系统电压相量平面特性。在此基础上,基于故障点与保护安装处的序电流关系,结合风电场侧的零序阻抗特点,建立了测量电压与故障点电压相位关系的表达式。根据故障点电压和整定电压的相位特性,考虑双馈风电机组的频率偏移特性,提出了直驱风电场联络线单相自适应接地距离保护方案,并对其动作性能进行了仿真验证。大量仿真结果表明,该保护方案判别原理简单可靠,有较强的耐受过渡电阻能力,不受风电场侧运行工况多变的影响,能够准确判别区内及区外故障。

In allusion to mal-operation or miss operation problems of single-phase grounding distance protection for wind farm tie line caused by transition resistance bringing about inaccurate impedance measurement, voltage vector plane characteristics of double-supply systems are analyzed. Based on sequence current relationship of fault point and relay installation location, combined with wind farm side＇s zero sequence impedance characteristics, relationship expressions of measured voltage and fault point voltage are set up. According to phase angle characteristics of fault point voltage and setting voltage, a novel single-phase adaptive grounding distance protection scheme for tie line of PMSG wind farm, considering frequency deviation characteristics of DFIG, is put forward. Its operating performance is validated with simulations. Simulation results show that the proposed scheme is simple, reliable and immune to transition resistance. Besides, it is not affected by various operation conditions of wind farm, and can discriminate internal and external fault correctly.