基于零序电流群体比幅比相的选择性漏电保护新方案

New selective earth leakage protection scheme based on zero-sequence current amplitude and phase comparison

推导了煤矿井下低压电网不同位置发生单相漏电时的零序电流计算公式,用电流相量的实部和虚部比较了各零序电流的幅值关系与相位关系,并提出了一种新的选择性漏电保护方案。通过Matlab仿真与快速傅里叶变换(FFT,Fast Fourier Transform)对该方案进行了验证。结果表明,此方法不仅可以实现漏电保护的横向、纵向选择性,而且无需采集零序电压,既提高了漏电保护的可靠性,又降低了硬件成本。

Deduced zero-sequence current formulae when single-phase earth leakage happened in underground low voltage distribution networks＇ different places,compared zero-sequence current amplitude relationships and phase relationships with current phasor＇s real part and imaginary part,and proposed a new selective earth leakage protection scheme.The scheme was verified by simulation via Matlab and calculation via Fast Fourier Transform.The results indicate that this method achieves lateral and longitudinal selectivity,avoids zero-sequence voltage＇s collection,enhances protection reliability,and cuts hardware＇s cost.