摘要
柔性直流输电(voltagesourceconverterbasedhigh voltage direct current transmission,VSC-HVDC)已成为海上风电远距离、大容量送出必然的发展方向。然而,海上风电场汇集升压接入VSC-HVDC换流站的交流线路两端均体现电力电子受控源特征,系统的故障特征发生了根本性变化。近端严重的交流故障可能引起VSC-HVDC换流设备闭锁,此时系统中故障电流持续时间短暂,失去故障特征后传统交流线路保护面临严重的不正确动作风险。针对该问题,提出基于奇异值分解的交流线路保护新原理。对交流线路两侧短路电流分别构造Hankel矩阵,综合利用Hankel矩阵能够快速反映信号及信号的导数奇异性的特点,以及奇异值分解法可以使用短窗提取波形特征的优点以实现故障的快速识别,所提原理可以利用VSC-HVDC换流器闭锁前故障特征可靠实现故障区段、类型的识别,从而解决传统保护因故障特征消失引发的不正确动作问题。在PSCAD中搭建了海上永磁风电场VSC-HVDC并网的精细化电磁暂态模型,通过仿真验证了所提保护原理的有效性。仿真结果表明,所提方法能够快速、可靠地识别区内、外各种类型故障,故障识别时间小于5ms,解决了传统保护在该场景下的不正确动作问题。
The voltage source converter based high voltage direct current transmission(VSC-HVDC)technology has become the inevitable development of the long-distance and large capacity transmission of offshore wind farms.However,the fault characteristics of the VSC-HVDC power system with the offshore wind farm have changed fundamentally because both sides of the AC line are power electronic power sources.Severe AC fault near the converter station may cause the blocking of the converter.This directly results in the short duration of fault current during AC faults,and conventional AC line protection faces serious problems of the incorrect operation.In order to solve this problem,a novel fast AC protection based on the singular value decomposition(SVD)was proposed.The Hankel matrix for fault current on both sides of the AC line has been constructed.Since the Hankel matrix can quickly reflect the singularity of signal and its derivative,and the SVD method can use short time window to extract waveform features,the fast fault identification was realized.The proposed protection can use the fault features before the blocking of the flexible DC converter to reliably identify the fault,so as to solve the problem of incorrect operation caused by the disappearance of the fault features of the traditional protection.A detailed model of VSC-HVDC system with offshore wind farms was built in PSCAD,and the effectiveness of the proposed protection was verified by simulation.The simulation results show that the proposed method can identify all kinds of faults quickly and reliably.The fault identification time is less than 5 ms,which solves the incorrect operation problem of conventional protection.
作者
郑黎明
贾科
侯来运
毕天姝
ZHENG Liming;JIA Ke;HOU Laiyun;BI Tianshu(State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources(North China Electric Power University),Changping District,Beijing 102206,China)
出处
《中国电机工程学报》
EI
CSCD
北大核心
2020年第S01期75-83,共9页
Proceedings of the CSEE
基金
国网公司科技项目(面向柔性直流接入的交流侧新型保护控制设计技术研究)
关键词
奇异值分解
海上风电
柔性直流
交流线路保护
singular value decomposition
offshore wind farm
voltage source converter based high voltage direct current transmission(VSC-HVDC)
AC line protection
作者简介
郑黎明(1996),男,博士研究生,研究方向为新能源电力系统保护与控制,771501846@qq.com;通信作者:贾科(1986),男,教授,博士生导师,研究方向为电力系统保护与控制、新型配电网保护与故障定位,ke.jia@ncepu.edu.cn;侯来运(1996),男,硕士研究生,研究方向为新能源电力系统短路电流计算,1071702153@qq.com;毕天姝(1973),女,教授,博士生导师,研究方向为电力系统保护与控制、广域同步相量测量技术及应用。
