基于相电流间相位关联特征的馈线单相接地保护新原理

配电网单相接地故障时,故障馈线上的故障相暂态电流分量包含了所有馈线上非故障相的暂态电流分量,经复小波变换后故障馈线的各相之间形成幅值和相位之间相对关联特征.依据此特征提出了基于组合复小波频带等效相位判据构成单相接地保护新原理.该保护是依据三相暂态电流之间存在相位关联特征,经组合复小波变换提取频带等效相位特征构成保护相位特征判据,并在判据中引入消除坏数据影响的风险系数.大量仿真验证了所提出的保护原理能够准确地判别单相接地故障,具有较高的可靠性和灵敏度,无须整定计算,自适应能力强,适合于非有效接地方式的各种配电网;保护方式可直接融合于间隔单元中,并作用于一次性重合方式,可大大提高供电可靠性.

NEW PRINCIPLE OF SINGLE-PHASE-TO-GROUND FAULT PROTECTION FOR FEEDERS BASED ON THE PHASE ASSOCIATED FEATURE OF PHASE TRANSIENT CURRENT

The faulty phase transient current component (TCC) of faulty feeder is composed of the healthy phase TCCs of all feeders including the faulty one, and then a combinatorial complex wavelet transform (CCWT) sequence is formed in every phase of the faulty feeder, which will lead to relative associated features of magnitude and argument between the phases when single-phase-to-ground fault occurs in the distribution network. First a new principle of single-phase-to-ground fault protection for the faulty feeder is proposed by extracting the equivalent band phase features between the phase CCWT sequences and regards it as the protection criterion. A risk coefficient is introduced into this criterion to eliminate bad data in the CCWT sequences. It has been verified by ATP simulations that the protection principle proposed can correctly distinguish single-phase-to-ground fault and is highly reliable, sensitive and adaptable without the need for setting calculation and is used for all kinds of distribution systems. This kind of protective mode can be merged with the gap units and conveniently realize the disposable auto-reclosing mode to greatly enhance the reliability of power supply.