含逆变型分布式电源的配电网智能分布式保护

Intelligent Distributed Protection for Distribution Network with Inverter-based Distributed Generation

为解决含分布式电源配电网的保护选择性问题,提出一种基于通信的智能分布式保护方案。本文分析了逆变型分布式电源的双闭环控制策略及抑制负序电压的控制方案。基于这类电源在系统发生不对称故障时只输出正序电流及对原有配电网负序电流分布和大小没有影响的特征,利用两段式负序电流保护和两段式正序方向电流保护分别反应不对称故障和三相短路的智能分布式保护方案。该方案仅在每条线路的电源侧设置保护装置,借助于通信通道和保护装置整定值的相互配合实现全线路故障的0 s跳闸,不需要随着分布式电源的接入与否改变整定值。PSCAD/EMTDC仿真验证了该保护方案的有效性。

To solve the problem of protection selectivity in distribution network with distributed generation(DG),a communication-based intelligent distributed protection scheme is proposed in this paper.The double closed-loop control strategy for inverter-based DG and the control scheme for restraining negative-sequence voltage are analyzed.Based on the characteristics that this kind of power source only outputs positive-sequence current under an asymmetric fault in the system and has no effect on the distribution and magnitude of negative-sequence current in the original distribution network,the intelligent distributed protection scheme is adopted,in which two-stage negative-sequence current protection and two-stage positive-sequence current protection are used to reflect the asymmetric fault and three-phase short-circuit fault,separately.In this protection scheme,the protection device is only installed on the source-side of each line,the instant tripping under fault on the whole line is realized by means of communication channels and the cooperation of protection setting values,and the setting value does not need to be changed with the access of inverter-based DG.The simulation results on PSCAD/EMTDC verify the effectiveness of the proposed protection scheme.