Modelling for on-line partial discharge monitoring on MV cables by using a modified Universal Line Model

The overall cable insulation condition can be monitored continuously by the implementation of an on-line partial discharge (PD-OL) monitoring system. It can both detect and locate the sources of PDs and also assess the insulation condition by using past data. The utilization of an accurate electromagnetic transient model is crucial for the accuracy of the system. Therefore, the well known Universal Line Model (ULM) is chosen to be used for the modelling of PDs propagation through underground medium voltage (MV) cables. For that purpose the ULM is properly modified in order to be able to take into account the PDs occurring among the two terminals of a cable section. The proposed approach also indicates the way that frequency dependent cable terminations can be included as well as the time varying noise existent at the points of measurements.