Measuring PD propagation in complex MV distribution network configurations

Abstract

The presence of Partial Discharge (PD) activity in an electrical network indicates potential future failures that could be prevented knowing the PD source location. Although several location techniques are used, the accurate location in complex configurations is a difficult task because the PD pulse is attenuated, dispersed and reflected according to the cable system configuration. The pulse shape is also distorted and measurements are influenced by high amplitude noise and other external interference. This paper investigates the behaviour of PD pulses propagation in a laboratory controlled medium voltage network that allows reconfiguration and repeatability under the same conditions. An online PD monitoring system is used to register the PD activity and a time-of-flight (TOF) method is applied to determine the time of arrival of pulses at different points of this network. The pulse propagation velocity is subsequently calculated. The main objective is to determine if the presence of different components, like transformers, switchgears, substations, busbars, etc. significantly affects propagation. An average propagation velocity throughout the cable system will be calculated. It will be determined if this value is useful in determining PD source location and its relative error.