逆变型分布式电源T接线路后纵联差动保护的改进方案  

An Improved Scheme of Longitudinal Differential Protection for Teed Lines With Inverter-Based Distributed Generations

作　　者：刘幸蔚 李永丽[1] 陈晓龙[1] 张惠智 

机构地区：[1]智能电网教育部重点实验室(天津大学),天津市南开区300072

出　　处：《电网技术》2016年第4期1257-1264,共8页Power System Technology

基　　金：国家自然科学基金项目(51177108);中国南方电网公司重点科技项目(K-KY2013-116)~~

摘　　要：当逆变型分布式电源(distributed generation,DG)以T接的方式接入高压配电网时,仅依靠提高电流纵联差动保护的整定值可能导致保护拒动。首先分析了逆变型DG的接入对电流纵联差动保护带来的影响。然后,利用线路母线电压互感器的信息,提出了以线路两端正序补偿电压的差值作为辅助判据的解决方案,并利用正序补偿电压和正序差动电流的相位关系消除动作死区。该方案简单易行,能够实现全线速动,并且不受DG容量、过渡电阻及两侧系统电势相角差等因素的影响。最后,基于PSCAD仿真平台搭建了含逆变型DG的110 k V高压配电网模型,对传统的电流纵差保护及改进的纵差保护进行了对比,验证了改进后保护方案的可靠性和有效性。When inverter-based distributed generation（DG） is connected to distribution network with a teed line, longitudinal differential protection may fail to operate only by raising setting values. Based on information from potential transformers on high voltage bus, a protection scheme was proposed, using difference between positive-sequence compensating voltages as an assistant criterion. Using phase difference between positive-sequence compensating voltage and positive-sequence differential current, fault dead zone can be eliminated. This protection scheme is simple and practicable. The new scheme could not only realize immediate trip, but be immune to influence from capacity of DG, transient resistance, angular phase difference of the system potential, etc. At last, a case model of 110 kV high voltage distribution network with inverter-based DG was built in PSCAD. Compared with traditional longitudinal differential protection, reliability and effectiveness of the improved scheme was verified.

关 键 词：逆变型分布式电源 T接线路 正序补偿电压 正序差动电流 相位差 

分 类 号：TM65[电气工程—电力系统及自动化]