A study on accuracy of fault locator in distribution system with distributed generations

A fault locator system in a loop-shaped distribution system with inverter based distributed generations is proposed. An algorithm of proposed fault locator system is based on the impedance obtained by the phase-voltage and line-current at the transformer feeder in the power distribution substation. We have proposed the quadratic equation expressed in terms of fault location. The quadratic equation represents the impedance from the substation to the fault location. Inserting the impedance obtained by the voltage and current at the transformer feeder into the quadratic equation, two candidates of the fault location are obtained. We can select the true fault location from the two candidates by using the characteristics of impedance calculated by the voltage and current at the incoming feeder of distributed generation. The validity of the fault locator system was investigated by PSCAD/EMTDC simulations. As a result, it was found that impedance obtained by the information of the substation and distributed generations are useful for searching the fault location in the loop-shaped distribution system.