自适应幅值比的有源配电网差动保护方案

Adaptive distribution network differential protection scheme with adaptive amplitude ratio

分布式电源大量接入配电网,改变了传统配电网单侧电源结构,易导致配网线路中出现双向潮流、电压越限和潮流波动等问题。文章首先分析了基于恒定功率控制的逆变型分布式电源故障特性以及有源配电网故障特性,提出了具有自适应幅值比的有源配电网差动保护方案。利用端电流的相位差自适应调整保护方案的幅值约束条件:在区内发生故障时,可以减少制动范围,防止保护拒动;在区外发生故障时,则可以增加制动范围,防止保护误动。最后,在PSCAD中搭建相关仿真模型,对所提有源配电网保护方案进行验证,结果表明该保护方案具有良好的适应性。

A large number of distributed power sources are connected to the distribution network,which changes the single-side power supply structure of the traditional distribution network,resulting in bidirectional currents,voltage overshoots,and tidal fluctuations in distribution network lines.Firstly,the fault characteristics of inverter-type distributed power supply based on constant power control and the fault characteristics of active distribution network are studied.The differential protection scheme of active distribution network with adaptive amplitude ratio is proposed in this paper.The phase difference of the terminal current is adopted to adaptively adjust the amplitude constraint of the protection.When the fault occurs in the zone,the braking range is reduced to prevent the protection from being rejected.In the case of an out-of-zone fault,the braking range is increased to prevent the protection from malfunctioning.Finally,the simulation model is built in PSCAD to verify the proposed protection scheme of active distribution network.The simulation results show that the proposed protection scheme has good adaptability.