含逆变型分布式电源的配电网新型纵联保护

Novel pilot protection for distribution networks with inverter interfaced distributed generation

为提升含逆变型分布式电源(inverter interfaced distributed generation, IIDG)的配电网电流差动保护的灵敏度,分析IIDG与同步发电机故障电流波形差异,当线路发生区内故障时,两侧电流波形差异很大;当线路发生区外故障时,两侧电流波形差异较小,从而提出了一种基于线路两侧电流波形相似度系数的纵联保护方案。利用线路两侧电流的余弦相似度的差异,构造相似度系数,从而实现保护的整定。仿真结果表明:该保护方案能正确识别区内、区外故障,耐受过渡电阻及抗同步误差的能力良好,与传统电流差动保护相比,灵敏度得到有效提高。

To improve the sensitivity of current differential protection for distribution networks with inverter interfaced distributed generation(IIDG),this paper analyzes the differences in fault current waveforms between IIDG and synchronous generators.There are huge differences in current waveforms on both sides when in-area faults occur on the line,and relatively small differences in current waveforms on both sides when out-of-area faults occur on the line.A longitudinal protection scheme is proposed based on the similarity coefficient of current waveforms on both sides of the line.The similarity coefficient is built by utilizing the differences of cosine similarity between the two sides of the line currents,so as to realize the adjustment of the protection.The simulation results show the protection scheme correctly identifies in-area and out-of-area faults,deals well with transition resistance and synchronization error.Moreover,it effectively improves the protection sensitivity compared with the traditional current differential protection.