Partial Discharge Localization along Medium Voltage Cables

Statistics indicate that more than 85% of equipment failures are related to insulation failure. Such faults can lead to brownouts and blackouts and in the transportation electrification context can also impact the safety of personnel or jeopardize missions, which is highly unacceptable. In this regard, predicting a fault before it occurs to do planned maintenance is needed where partial discharge (PD) activity can be used as an indicator. The paper presents a model based on the time of arrival (ToA) approach for PD localization in medium voltage (MV) cables which are a critical component in powertrains and distribution grid connections. The cable considered, which is a three-phase MV cable with three single-core armored copper conductors is modeled using a frequency-dependent wideband model in EMTP. The model accurately represents the cable's behavior by incorporating the skin effect and the impact of semiconducting layers on signal propagation. The attenuation coefficient is calculated for varying frequencies and lengths to evaluate the effect of the semiconducting metallic screen and attenuation voltages. An empirical relationship is developed by injecting PD signals at predefined locations and analyzing arrival time differences at cable terminals, linking propagation velocity, cable length, and ToA. The proposed methodology ensures precise PD localization, highlighting its potential for enhancing diagnostic accuracy in cable systems.