Investigation of conduction processes of dielectric liquids by means of simulation, electro-optic Kerr-effect measurements and PDC measurements

Conference: VDE-Hochspannungstechnik 2018 - ETG-Fachtagung
11/12/2018 - 11/14/2018 at Berlin, Deutschland

Proceedings: ETG-Fb. 157: VDE-Hochspannungstechnik

Pages: 6Language: englishTyp: PDF

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Authors:
Oeftering, Hans-Peter; Kuechler, Andreas (FHWS University of Applied Sciences Würzburg-Schweinfurt, Schweinfurt, Germany)
Rumpelt, Patrick; Jenau, Frank (Technische Universität Dortmund, Dortmund, Germany)
Fritsche, Ronny (Siemens AG, Nürnberg, Germany)

Abstract:
In order to guarantee a successful and accurate operation of high-voltage direct current (HVDC) plants, the equipment has to be designed economical and efficient. The design of the insulation system is a challenging task, because the components are stressed both by AC and by DC voltages. Therefore, further parameters, like the electrical conductivity, become more important. Based on polarization and depolarization current (PDC) measurements, the characterization and the prediction of the electrical conductivity is fundamental. Modelling of insulation systems under the mentioned voltage stress is very time-consuming and cannot be solved by a usual RC model. Under the influence of high DC voltages, mineral oil has strong non-linear properties, so a constant resistance cannot model the electrical conduction behavior. Thus, the Poisson-Nernst-Planck (PNP) model is used, whereby the behavior of the individual charge carriers is considered. By modelling the physical processes, it is possible to predict the behavior of an insulation system, e.g. a mineral oil duct. Beside of this physical approach to model the behavior of an oil duct, measurements are done in order to verify the predicted dielectric behavior of the mineral oil. PDC measurements help to get a profound knowledge about the timedependent conduction processes. Electro-optic Kerr-effect measurements are done in order to characterize the steady state electric field distortion in a 5 mm oil gap. The developed simulation model, based on the PNP equation, is used to predict the electric field distribution as well as the time-dependent current with one set of parameters.