Research Papers - Department of Electrical and Electronic Engineering

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Author: search.filters.author.Darwin, A

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    An electrical PD location method applied to a continuous disc type transformer winding
    (IEEE, 2003-06-01) Hettiwatte, S. N; Wang, Z. D; Crossley, P. A; Jarman, P; Edwards, G; Darwin, A
    A 6.6 kV continuous disc type winding of a distribution transformer is used to investigate the propagation of partial discharges (PD) with the aim of location. The winding was modelled, as multiconductor transmission lines with each turn represented by a transmission line. This approach results in the model being valid up to a few MHz in frequency. The validity of the model was confirmed by impedance measurements on the winding. The transfer functions calculated between probable PD source locations to winding terminals showed that the troughs (or zeros) change in frequency with the location of PD source and hence can be used for the location of PD. Transfer functions obtained experimentally using a discharge calibrator as the PD source, showed very good agreement with the calculations.
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    Experimental investigation into the propagation of partial discharge pulses in transformers
    (IEEE, 2012-01-27) Hettiwatte, S. N; Wang, Z. D; Crossley, P. A; Darwin, A; Edwards, G
    An experimental investigation into the propagation behaviour of partial discharge (PD) pulses in a continuous disc type 6.6kV transformer winding is described in this paper. PD pulses were injected into the winding using a calibrator and the resulting current signals at the line and neutral end terminals measured using wide band current transformers. The location of the troughs (or zeros) in the frequency spectra of the measured signals change in accordance with the position of the injected pulse. The crests (or poles) in the spectra convey information about the resonance frequencies of the winding and are not affected by the position of the injected pulse. The measured spectra are compared with the spectra generated by a simulation model and although differences exist the overall shape and location of the poles and zeros are similar.
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    Simulation of a transformer winding for partial discharge propagation studies
    (IEEE, 2002-01-27) Hettiwatte, S. N; Crossley, P. A; Wang, Z. D; Darwin, A; Edwards, G
    A simulation model of a continuous disc type 6.6 kV transformer winding was used to study the propagation behaviour of partial discharge (PD) pulses. The model based on multi-conductor transmission line theory uses a single turn as a circuit element with the capacitance, inductance, and losses calculated as distributed parameters. Transfer functions that describe how the location of the PD source affects the current signals measured at the terminals of the winding were calculated. The paper shows how the position of the zeros in the frequency response of the measured current signals can be used to locate the source of the discharge. Sensitivity studies on the parameters of the model were used to investigate the effect of inaccuracies in the model on the position of the zeros and hence the location of the discharge.