分布式电源并网条件下配电网继电保护方案设计

Design of relay protection scheme of distribution network with DG

分析了DG并网对配电网故障电流的影响,并提出一种改进保护方案。方案利用含DG配电网的故障电流特征,采用两侧电流的相角变化量作为判据进行故障定位,由始端保护装置实现主电源到DG接入点之间故障的判别。方案对电流幅值的精确度要求不高,能有效避免系统运行方式变化产生的影响,简单可靠;仅需要传输反映电流相角变化方向的数字信号和保护决策信号,对通信通道要求不高;仅需要采集故障前后的电流信息量,节省了电压互感器,对配电网而言具有良好的经济性。仿真实验证明其可行性。

This paper analyses the effects of DG supply to distribution network＇s fault current, and proposes an improved protection scheme. The scheme utilizes the fault current characteristics of the DG distribution network, refers to the phase angle change of the current at both sides of the line, control from the beginning, to determine the fault between the main power supply and the DG access point. The request of current amplitude＇s accuracy is not high, and it is not influenced by the system operation mode, simple and reliable; only the digital signal reflects the change direction of current phase angle and protection decision signal need to transmit, communication channel requirement is not high; only the current information collected before and after the fault is required, saving the voltage transformer and having a good economy for the distribution network. The simulation experiment proves its feasibility.