某光伏电站35 kV同塔四回送出线路零序电流过大原因分析及改善措施

Cause Analysis and Improvement Measures about Excessive Zero-Sequence Current of 35 kV Quadruple-Circuit Transmission Lines on the Same Tower in a Photovoltaic Power Station

广西某光伏电站采用35 kV同塔四回架空线路送出,电站扩容并网后,多次发生零序过流跳闸事故,严重影响电站电能送出。笔者采用理论分析和数值仿真相结合的方法,分析零序过流跳闸的原因,并提出相序优化布置方案,采用数值仿真工具验证所提方案的有效性;分析同塔四回线路在n-1故障状态下存在的问题,提出避开零序过流保护误动的建议。结果表明:跳闸故障是由于同塔四回线路相序布置不当引起的;优化方案的实施可有效解决送出线路中零序过流问题,现场测量结果与仿真计算结果基本一致,验证所提优化方案的正确性和有效性。研究成果可为同塔多回线路零序过流问题的分析和处理提供借鉴。

A photovoltaic power station in Guangxi is sent out by 35 kV quadruple-circuit transmission lines on the same tower.After the expansion and grid connection of the power station,zero-sequence overcurent tripping accidents occurred many times,which seriously affected the power transmission of the power station.In this paper,the causes of zero-sequence overcurrent tripping are analyzed by combining theoretical analysis with numerical simulation,and the phase sequence optimization layout scheme is proposed.The efectiveness of the proposed scheme is verified by numerical simulation tools.The problems existing in the n-1 fault state of the quadruple-circuit transmission lines on the same tower are analyzed,and the suggestion of avoiding the misoperation of zero-sequence overcurrent protection is put forward.The results show that the tripping fault is caused by improper phase sequence arrangement of quadruple-circuit transmission lines on the same tower;The implementation of the optimization scheme can effectively solve the problem of zero-sequence overcurrent in the transmission line,The field measurement results are basically consistent with the simulation results,which verifies the correctness and effectiveness of the proposed optimization scheme.The research results can provide reference for the analysis and treatment of zero--sequence overcurrent problem of multi-circuit transmission lines on the same tower.