Enhanced Line Pilot Impedance Algorithm Based on Parameter Identification

摘要

This paper proposes a novel enhanced transmission line pilot impedance algorithm based on parameter identification, which is defined by the fault component sampling values of voltages and currents at both terminals of this line, and is used to distinguish the internal faults from the external faults. For the external fault, the magnitude of the computing inductance or resistance are greater than the determining data based on the series positive sequence inductance or resistance of the protected line, whereas they are smaller than the aforesaid setting values for the internal faults. The algorithm eliminates the inter-phase coupling caused by the unbalanced grounding fault, so it is the individual phase protection algorithm and possesses the high stability and reliability and immunes to the influence of load state and fault resistance. Performance analysis shows that the algorithm can be used various length lines through the line capacitances time domain compensation and may directly apply the line including the series compensating capacitors. Because the algorithm uses the short data window criterion, it has the short operating time and the little influence of transient components. It builds 1000kV 500km line model on EMTP, uses a laboratory model simulation data of a power system from Lan Zhou Dong to Xian Yang 750kV, executes the simulations under each fault. The simulation results indicate the fact that this algorithm can judge the aforesaid various fault state.