Pd Patterns Recognition in Xlpe Cable under Various Thermal Conditions Using Statistical Technique

Condition monitoring of partial discharge (PD) has become a preferred method in the design of HV apparatus. Power cable is one of the HV apparatus affected by PD activity. Although, the phenomenon of PD in power cables are well known, the effect of soil thermodynamics on PD is not yet well established. Thus, an experiment has been carried out to assess the effect of soil thermal resistivity on various PD parameters at different temperatures. Cable sample studied is an 11kV, single core, 240mm 2 XLPE cable. Classification is firstly carried out using the conventional method “Recognition Rate”. A proposed method, which is called “Hitting Pattern”, is then introduced to overcome the limitation of “Recognition Rate”. Classification using “Hitting Pattern” emphasises on the patterns of discharge, which is not considered by the “Recognition Rate”. These two techniques are developed with the help of 27 statistical parameters, so called “classifiers”, which are calculated using PD Analyzer Programme developed in-house. The values of classifiers of standard physical condition are used to classify PD patterns of non-standard physical conditions. The authors have also discussed about the simplified version of “Recognition Rate”, which is called “Fingerprint”, for the easier observation purposes.