SINGLE-PHASE EARTH-FAULT DIAGNOSIS METHOD FOR ULTRA-HIGH-VOLTAGE ALTERNATING-CURRENT TRANSMISSION LINE

摘要

A single-phase earth-fault diagnosis method for an ultra-high-voltage alternating-current transmission line. In the method, the lumped-parameter model is first used to build a model, then fault distance is calculated on the basis of the linear relationship between the voltage drop from the relay location of the ultra-high-voltage alternating-current transmission line to the single-phase earth-fault point and on the basis of the fault distance. Next, a long-line equation is used to precisely describe the physical properties of the voltage and current transmission of the ultra-high-voltage alternating-current transmission line; and the calculated fault distance is used to calculate the compensation current of the transmission line. Thus, ultra-high-voltage alternating-current transmission line single-phase earth-fault diagnosis criteria are used for precision diagnosis of a single-phase earth-fault on an ultra-high-voltage alternating-current transmission line. The method is suitable for use in single-phase low/medium/high resistance earth-fault diagnosis during the overall fault process of an ultra-high alternating-current transmission line. Diagnosis is not affected by such factors as transition resistance, load current, and system operation mode.