面向多端直流电网的相继速动判据  

Dead Zone Acceleration Principle for the Multi-terminal DC System

作　　者：郑宇超 童宁[1] 林湘宁[1] 随权 汪致洵 李正天[1] ZHENG Yuchao;TONG Ning;LIN Xiangning;SUI Quan;WANG Zhixun;LI Zhengtian(State Key Laboratory of Advanced Electromagnetic Engineering and Technology,Huazhong University of Science and Technology,Wuhan 430074,Hubei Province,China)

机构地区：[1]强电磁工程与新技术国家重点实验室(华中科技大学),湖北省武汉市430074

出　　处：《中国电机工程学报》2020年第23期7622-7634,共13页Proceedings of the CSEE

基　　金：国家自然科学基金项目(51907069);国家电网公司科技项目(5100-201999331A-0-0-00)。

摘　　要：基于单端量的保护现今成为多端直流电网的主保护,但由于其自身特点无法保证对线路上所有位置故障有相同灵敏性,因此一旦在不灵敏区发生故障,会造成本侧保护拒动,换流器可能会因故障不完全隔离而无选择性闭锁,影响系统稳定性。该文在深入分析故障产生的一次波过程与直流断路器动作催生的二次波过程特征的基础上,利用两次波过程首波头的时域差异性构造一种新型时差判据;同时,利用二次波过程在区内/区外故障工况下的频域差异性构造一种过零点计数判据。两判据保护范围互相补充,可保证死区故障加速跳开,形成一种类似于交流主网相继速动的原理。仿真结果表明,该文原理可以不依赖通信系统独立动作,经速动性分析,该原理可在换流器闭锁前完成死区故障快速隔离,通过与现今主保护配合可使得多端直流电网运行水平进一步提升。The single-ended protection has become the main protection of multi-terminal DC grid. However it cannot have the same sensitivity for each fault location of the protected line because of self-feature. Therefore, if the fault happens in the one-sided dead zone, the local protection will refuse to act. The inverter won’t be selectively blocked due to incomplete isolation of faults, and will affect the stability of system. Based on the deep analysis of the characteristics of first wave induced by fault and the secondary wave induced by DC breaker action, this article proposed a new time difference criterion by using the difference of two wave processes in time domain, and a zero-crossing count criterion by using the frequency difference of the secondary wave process in frequency domain. The applicable scope of two criteria covers each other and guarantee accelerating removing the dead zone fault. The proposed criteria form a fast sequential acting principle similar to the AC main network. The results of simulation show that the proposed principle can achieve the fast sequential acting without communication system. After the analysis of the protection quickness, the protection can complete fast fault isolation before the converter is turned off. It also can be used in conjunction with the existing main protection to further improve the operation level of the multi-terminal DC grid.

关 键 词：单端保护 行波 多端直流电网 直流断路器 

分 类 号：TM77[电气工程—电力系统及自动化]