基于估算对侧电源阻抗的自适应距离保护算法

Adaptive Distance Protection Algorithm Based on Estimation of Contralateral Source Impedance

在系统两端电源电势幅值比相等的假设下,基于故障前电源电势与负荷电流之间的相位关系合理地估算出对侧电源阻抗值。利用传统距离保护的测量阻抗和保护处实时相量建立起计算线路故障电抗和电阻的自适应数学模型,2个模型都为正序电流分支系数的相角的函数。根据测量阻抗的电抗分量和电阻分量与正序电流分支系数的相角之间的增减关系分别提出了防止保护拒动和超越的解决办法。仿真结果证明,这种距离保护性能令人满意,提高了保护的可靠性和灵敏度。

Under the assumption of equal electromotive force（EMF） amplitude ratio of both ends in power systems,based on the pre-fault phase relationship between EMF and load current the contra-lateral source impedance is legitimately estimated.With measured impedance of traditional distance protection and real-time phasors on protection location,adaptive math models for calculating both resistance and reactance of line fault are established.Both models are functions of positive-sequence current branch coefficient phase angle.According to increase or decrease relationship between reactance,resistance components of measured impedance and positive-sequence current branch coefficient phase angle,two cases solutions are separately proposed in order to prevent overreaching and under-reach problems of distance relay.Simulation results show that the adaptive distance protection has satisfactory performance,enhanced reliability and high sensitivity.