Lumped Parameter Model for High Frequency Partial Discharge Estimation in High Voltage Transformer

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Description/Abstract

The lumped parameter model is well known in solving high frequency signal propagation in high voltage transformer windings. At the University of Southampton, a modelling technique has been developed and employed to locate partial discharges (PD) that occur inside transformer windings. Firstly, a lumped capacitive parameter model was considered and secondly a transmission line lumped parameter approach developed. A technique of split winding analysis is introduced for both types of model. The derivation of the capacitive network considers the source location of a PD by defining the PD signal propagation in two directions. At the source, the currents are equal in magnitude and are attenuated as they flow in each direction. This provides information for a fixed distribution model equation. Under transmission line lumped parameter models, split winding analysis explains the development of accumulated harmonic waveforms of the PD propagation signal towards the neutral and bushing tappoint. Results indicate that this approach can also estimate the magnitude of PDs that occur within transformer windings.