一种改进型配网自适应过流保护方法

在DG构成的配电网系统中,通常采用电流保护作为配网的主保护。其中电流保护的整定值为定值,随着DG的接入,配电网结构发生变化,DG并入位置不同会带来故障点无法准确判定的问题。针对此问题,提出了一种基于通信的故障定位方案,具体是引入方向元件并建立信息传递通道检测电流流向来准确判定故障点位置。由于DG接入容量的不同和故障前后DG所发出电流数值变化,造成配网原有电流保护失配。针对此问题,提出一种改进型自适应过流保护算法,具体是通过检测故障电流正、负序含量,确定故障类型,采用不同的整定值,使得电流保护的整定值时刻变化,增强保护动作可靠性。将上述策略通过PCSAD/EMTDC仿真和动模实验室搭建实验模型来验证所提方案可以有效提高DG并网带来的保护动作准确性能。

A novel adaptive overcurrent protection method for a distribution network

In a distribution network system composed of DG, current protection is usually adopted as its main protection. The setting value of current protection is a fixed value. With the access of DG, the structure of the network changes. Different locations of DG merging into it will bring the problem that the fault point cannot be accurately determined. In response to this, we propose a communication-based fault location scheme. It introduces directional components to detect the current flow to accurately determine the location of the fault point. The difference in DG access capacity and the change in the current value sent by DG before and after the fault cause an original current protection mismatch in the distribution network. We propose an improved adaptive overcurrent protection algorithm. By detecting the fault current positive and active sequence components, it determines the type of fault, and then uses different setting values, so that the setting value of current protection changes at any time, enhancing the reliability of protection action. The above strategy is verified by PCSAD/EMTDC simulation and experiment and shows that the proposed scheme can effectively improve the accuracy of the protection action brought by DG grid connection. This work is supported by the Youth Fund of National Natural Science Foundation of China (No. 51807114).