This thesis presents an on-site partial discharge (PD) measurement tools which is one of the best methods in providing early detection before the occurrence of power breakdown in the major part of electrical distribution system. The repetition of PD operation at the defect site could cause insulation breakdown as the defect would extends until it crosses the electrodes between the insulation, and ended up with the entire network breakdown. In this study, an on-site PD measurement has been conducted at eight substation that used 11 kV cross link polyethylene (XLPE) underground power cables in order to assess the insulation condition that is based on the International Electro-technical Committee (IEC) 60270 standard. As insulation failure usually begins with PD activities, which is not only one of the primary reasons to cause the deterioration of the cable insulation, but also the characteristic scalar to describe the condition of cable insulation. Thus, IEC, IEEE and CIGRE propose PD diagnosis as an appropriate tool for determining the properties of the condition of cable insulation. In order to study the PD characteristics of the typical defects in XLPE power cable, four characteristics as rise time, zero crossing, peak amplitude and resonant frequency in main insulation were analysed based on the PD measurement established.The Rogowski coil (RC) has been developed and used as a PD measuring sensor in this measurement. In order to figure out the capability of the proposed measurement technique, the 11 kV distribution network with real parameters has been modelled using Electromagnetic Transient Program-Alternative Transient Program (EMTP-ATP). Next, the denoising process is based on Discreate Wavelet Transform (DWT) technique that has been conducted to discriminate between the interference noise and PD signal from the measured data. From the work conducted, it was found that, the technique and the RC sensor had indicated good significance for the PD measurement in both modelling and in on-site situations. Based on the on-site measurement results, it shows a similar PD pattern between the techniques conducted as compared to the conventional technique, which is recently practiced by electrical utility company. For the denoising technique, the Daubechies level 2 is found to be the best mother wavelet as compared to Symlet and Coiflet mother wavelets based on the analysis conducted. The characteristics of PD signal founded in this work within range 200 MHz are important in providing a good guideline for PD measurement activities in power cables especially during the utility maintenance work in the future. Additionally, the innovative portable PD monitoring system, which is integrated with the RC sensor, provides a reliable system for early detection prior to power breakdown in the electrical distribution system in the future.
