FIELD: electricity.
SUBSTANCE: invention relates to power industry, namely to distribution networks relay protection and automatics, operating in mode with insulated neutral. Summary: controlled feeder model is used. Input values - complex phase currents and voltages, obtained as result of observation of feeder in its beginning. At point of assumed damage load-carrying part of feeder model is exposed to three-phase voltage source, obtained for this point. Reaction of model loading part is fixed in form of normal feeder currents. Finding local currents feeder as difference of phase currents, obtained for this point, and components of normal currents. Comparing levels of feeder local phase currents at its input. Two phases of feeder with higher levels of local currents are identified as damaged. Currents of assumed faults in damaged phases are determined as difference of damaged phase local current and intact third phase local current in place of assumed fault. Assumed fault phase voltage and current of each of two damaged phases are converted in two information parameters of assumed fault point. Nearest to beginning of feeder place of transition of one of information parameters through zero value are determined as first feeder fault point, and phase of feeder, which belongs to this parameter is identified as first damaged feeder phase. Feeder model is shortened by length of intact part from feeder input to first fault point. Input voltages of shortened model are represented by phase voltages at point of first fault. Input currents of second and third phases of shortened model are represented by phase currents at point of first fault. Input current of first phase is represented by difference between corresponding phase current and fault current. In short feeder model its input currents and voltages are converted into secondary phase values of second expected fault point. Second fault current is determined, secondary phase voltage of second damaged feeder phase and second fault current are converted into assumed faults points of this phase information parameters and second fault to ground coordinate is determined.
EFFECT: simple method and enlarging its functional capabilities.
5 cl, 10 dwg
