EVALUATION METHOD FOR DETERMINING OF THE PROBABILITY OF AN ASYMMETRICAL FAULT LOCATION IN A DISTRIBUTION NETWORK AND A MONITORING SYSTEM FOR PERFORMING SUCH METHOD

摘要

Monitoring system for localisation of asymmetrical faults, comprising at least one monitoring unit and one evaluation unit, wherein a bi-directional communication is used between the evaluation unit and the monitoring unit and a control communication is used between the evaluation unit and a control unit, where the monitoring unit comprises at least one monitoring unit (1) of a negative sequence voltage and at least one monitoring unit (2) of a negative sequence current, wherein the monitoring unit (1) of a negative sequence voltage is intended for monitoring of time synchronised waveforms of the change of negative sequence voltage measured on a secondary side of distribution transformers (MV/LV) in a monitored section of a distribution network, the monitoring unit (2) of a negative sequence current is intended for monitoring and recording of time synchronised waveforms of the change of negative sequence current flowing through a supply transformer (HV/MV), the evaluation unit (3) is intended for determination of probability of asymmetrical fault presence or presence of a source of voltage/current unbalance in a monitored network on the basis of the changes of negative sequence voltage ” �¢ U S x 2 recorded by the monitoring units for given co-ordination time of a fault occurrence.