含分布式电源的配网自适应保护方案

摘要

For a distribution system with the interconnection of distributed generations (DG), DG may bring about negative effects on the power distribution system, especially the power system protection. The changing of direction and levels of fault currents will cause de-sensitivity and mal-operation of protection relays. In order to solve the problems, this paper summarizes the characteristic of the inverter-based DG (IIDG) during a fault, and then analyzes the relationship between the fault current and the I IDG capacity, which proves that the IIDG power output variation is in proportion to the fault current variation the relay feels. Based on the analysis results above, this paper presents an adaptive protection method, enabling the relay setting changes itself with the fault current level. The protection scheme has the advantages of simple principle, high-sensitivity, feasibility and practicability. Results of implementation of this scheme on an actual 10 kV distribution feeder using PSCAD/EMTDC prove its effectiveness and rationality.%针对分布式电源接入配网引起的短路电流方向及大小变化造成的保护误动、灵敏度降低等问题,总结了逆变型分布式电源故障特点、并分析了故障电流与分布式电源容量变化关系.分析结果证明三相短路故障时,逆变型分布式电源功率输出变化量与保护感受到的故障电流变化量成正比例关系.在此基础上,提出一种保护整定值随DG功率输出水平、故障电流水平同进退的配网保护新策略.该方案具备保护原理简单可行、灵敏度不受分布式电源影响、经济性好、实用性高的优点.最后应用PSCAD/EMTDC软件以10 kV实际配网系统为对象验证其具有有效性和合理性.