通信限制下多DG接入配网的新型电流差动保护

A novel current differential protection for multiple DGs accessing a distribution network with a communication limitation

差动保护是解决分布式电源(distributed generation, DG)接入下配电网保护难题的有效手段,然而配网现有通信建设水平很大程度上制约了差动保护的构建。首先,融合电流相位与相量差动保护思想,同时将电流相位信息进行变换,实现通信信息降容。应用递推最小二乘法实现短路电流相位参数的快速估计,提出了短路电流相位修正策略,以应对CT饱和与直流分量对保护的干扰。最后,提出适用于含多DG配网的新型电流差动保护构建原则与保护判据。基于PSACD/EMTDC平台搭建仿真模型,验证了所提出的电流相位参数预测方法的精度与新型差动保护的性能。算例结果表明:所提电流相位参数预测方法速度快、精度高,具有良好的抗CT饱和能力;所提新型差动保护原理具有良好的性能。

Differential protection is an effective means of solving the problem of distribution network protection with DG access.However,the existing communication construction level of a distribution network greatly restricts the construction of differential protection.In this paper,the idea of current phase and phasor differential protection is integrated,and the current phase information is transformed to reduce the capacity of communication information.It applies the recursive least squares method to achieve fast estimation of short-circuit current phase parameters,and proposes a short-circuit current phase correction strategy to address the interference of CT saturation and DC component with protection.Finally,the construction principle and protection criterion of new current differential protection suitable for a distribution network with multiple DGs are proposed.Based on the PSACD/EMTDC platform,a simulation model is built to verify the prediction accuracy of the proposed current phase parameters and the performance of the new differential protection.The results show that the proposed current phase parameter prediction method is fast,has high precision and good anti-CT saturation ability.The proposed new differential protection principle shows good performance。