Evaluation of probability functions related to short circuit random variables using power quality meters

This paper deals with a methodology to obtain the probability functions related to variables involved in the short circuits in power systems, namely impedance, location, duration and type of fault. This information is obtained from real measurements taken from power quality monitors in distribution substations. The proposed methodology makes use of a fault location algorithm (FLA) in radial networks, which deals with the waveforms acquired whenever a behavior alteration is detected. In this case an event is generated to obtain: i) the voltage and currents waveform prior and during the fault, ii) the type of fault and iii) the fault duration. The FLA uses voltage and current values to obtain the possible fault location and impedance. Different events in a real distribution network are evaluated during the monitoring period, which allows for the evaluation of probability functions for each studied variable, thus showing the adequate statistic parameters for short circuit and power quality studies.