Electrical Modeling of High Voltage Windings of Power Transformers for Online Partial Discharge Localization

Partial discharge (PD) is one of the most critical factors contributing to the gradual destruction of transformer insulation, potentially leading to complete insulation failure if left unresolved. Accurate physical localization of PD faults within transformers is essential for effective maintenance and cost management. This paper presents an innovative online technique based on transfer function analysis for detecting and localizing PD within power transformers, which has been experimentally verified. Initially, the study considers transformer windings as single-layer disk windings with an air core. A suitable pulse generator is utilized to simulate PD signals in the laboratory environment. Voltage signals at the bushing and neutral ends are measured and used to derive mathematical equations and winding transfer functions via curve fitting techniques in MATLAB software. By comparing the frequency response with reference values, the precise location of PD is determined. The proposed method has been validated through experiments using a laboratory winding setup consisting of six disks.