@inproceedings{TargitayRothZinketal., author = {Targitay, Deniz and Roth, Lisa and Zink, Markus H. and K{\"u}chler, Andreas and Bier, Markus and Kobus, Maja and Geißler, Michael and Schlittler, Balz}, title = {An FEM simulation model of oil-pressboard insulating systems for HVDC transformers}, series = {23rd International Symposium on High Voltage Engineering (ISH 2023)}, booktitle = {23rd International Symposium on High Voltage Engineering (ISH 2023)}, publisher = {Institution of Engineering \& Technology}, pages = {7}, abstract = {In this contribution, a simulation model for the description of the nonlinear dielectric behaviour of an insulation system composed of mineral oil and oil-impregnated pressboard is presented. The model was verified by comparing the simulation results with electric field and current measurements. At the outset, the ideal case, where a homogeneous initial charge carrier distribution according to the definition of ohmic conductivity is present, is analysed to establish the preliminary foundations pertaining to a typical measurement. Following that, the influence of distinct charge carriers on the measured quantities are investigated by altering their parametrisations. In contrast to the ideal case, a real measurement reveals a current trend, that can be explained by an excess amount of initial charge carriers related to the oil-impregnated pressboard layers. Potential possibilities to the origin of the surplus are discussed. Furthermore, it is shown that the dissociable and intrinsic charge carriers alone can reconstruct the measured quantities in terms of the transient behaviour. This points out that, for the field strength studied here ( E ≤ 1 kV/mm ), the charging of the highly resistive pressboard barriers is dominated by the dissociation of charge carriers in the oil gaps.}, language = {en} } @inproceedings{HartmannHarrerDotterweichetal., author = {Hartmann, J{\"u}rgen and Harrer, S. and Dotterweich, C. and Zink, Markus H. and Hemberger, Frank and Ebert, Hans-Peter and Schnitzler, Tim}, title = {Phase change materials for use in thermally and electrically stressed insulation for high voltage applications}, series = {2016 IEEE Electrical Insulation Conference}, booktitle = {2016 IEEE Electrical Insulation Conference}, publisher = {IEEE}, isbn = {978-1-4673-8706-4}, pages = {605 -- 608}, abstract = {The temperature of high voltage equipment is often the limiting factor when transmitting electrical energy because the electrical insulation can get severely aged when the temperature is exceeding a certain limit. Hence, cooling has to be improved or heat generation must be reduced to avoid damage of the insulation. In this paper a new method was examined by investigating electrically insulating phase change materials which are able to store latent heat during a phase change from the solid to liquid state in times of high energy demand. To verify the electrically insulating properties of paraffins, one class of phase change materials, a special test cell was designed allowing the determination of breakdown voltage of phase change materials. The measurements on one paraffin sample proved the promising electrical insulating properties and it was shown that the breakdown voltage in the liquid state is comparable …}, language = {en} } @inproceedings{HartmannHarrerDotterweichetal., author = {Hartmann, J{\"u}rgen and Harrer, S. and Dotterweich, C. and Zink, Markus H.}, title = {On the conduction process of dielectric liquids based on mineral oil}, address = {Buenos Aires (Argentinien)}, language = {en} } @inproceedings{ZinkDotterweichHartmannetal., author = {Zink, Markus H. and Dotterweich, C. and Hartmann, J{\"u}rgen and Harrer, S. and Hemberger, F. and Ebert, Hans-Peter and Schnitzler, Tim}, title = {Phase Change Materials for Use in Thermally and Electrically Stressed Insulation for High Voltage Applications}, series = {IEEE Electrical Insulation Conference}, volume = {2016}, booktitle = {IEEE Electrical Insulation Conference}, pages = {605 -- 608}, language = {en} } @inproceedings{KuechlerKriegLalaetal., author = {K{\"u}chler, Andreas and Krieg, A. and Lala, G. and Schober, F. and Wiener, J. and Paulus, J. and Zink, Markus H. and Liebschner, M.}, title = {FEM model for describing the dielectric behavior of oil-impregnated pressboard under DC stresses}, series = {33rd International Conference "Science in Practice"}, booktitle = {33rd International Conference "Science in Practice"}, address = {Schweinfurt}, language = {en} } @inproceedings{WirthReumannZinketal., author = {Wirth, Isabell and Reumann, Andreas and Zink, Markus H. and K{\"u}chler, Andreas and Langens, Achim and Schnitzler, Tim}, title = {Messung elektrischer und thermischer Transienten an Hochspannungsgleichstromdurchf{\"u}hrungen}, series = {Highvolt Kolloquium, Dresden, 2015 (Poster)}, booktitle = {Highvolt Kolloquium, Dresden, 2015 (Poster)}, language = {de} } @inproceedings{SturmWirthPaulusetal., author = {Sturm, Sebastian and Wirth, Isabell and Paulus, Johannes and Zink, Markus H. and K{\"u}chler, Andreas and Berger, Frank}, title = {Transient dielectric simulation in time domain with FEM in comparison with circuit models}, series = {XIX International Symposium on Theoretical Electrical Engineering, Ilmenau, 2017}, booktitle = {XIX International Symposium on Theoretical Electrical Engineering, Ilmenau, 2017}, language = {en} } @inproceedings{ZinkBergerKlipfeletal., author = {Zink, Markus H. and Berger, Frank and Klipfel, V. and K{\"u}chler, Andreas}, title = {Ageing Condition Assessment of 400 kV OIP Generator Transformer Bushings}, series = {17th ISH International Symposium on High Voltage Engineering}, booktitle = {17th ISH International Symposium on High Voltage Engineering}, address = {Hannover}, language = {en} } @incollection{KuechlerWirthReumannetal., author = {K{\"u}chler, Andreas and Wirth, Isabell and Reumann, Andreas and Zink, Markus H. and Schnitzler, Tim and Langens, Achim and Berger, Frank}, title = {Steady-state and Transient Electrical Potential Distributions in HVDC Bushings Measured under Different Thermal Conditions}, series = {19th International Symposium on High Voltage Engineering}, booktitle = {19th International Symposium on High Voltage Engineering}, address = {Pilsen, Czech Repbulic}, abstract = {High voltage DC (HVDC) applications become more and more important and the voltage level for energy transportation increases steadily. Hence the design of the DC insulation systems becomes more and more difficult. The difference between HVDC and HVAC insulation systems is that in HVAC the electrical field is distributed according to the permittivities of the materials. Permittivity is only weakly dependent on temperature, so there is no significant difference between the electrical field distribution at room temperature and operating temperature of the insulation system. In HVDC however the electrical field is distributed according to the conductivities of the insulation materials whereas the conductivity is strongly dependent on temperature. This can lead to completely different field distributions at varying temperatures. The investigations presented here show simulation results of HVDC bushing cores in comparison with measurements on those test objects. Simulations and measurements were performed both for temperature distributions and electric potentials of the grading layers in the bushing at DC voltage. For the first time, it was shown by experiment that the FEM simulation can reproduce real DC field distributions very well. It was also shown, that there is a strong influence of temperature gradients or temperature transients on transient and steady-state electrical potential distribution inside the insulation.}, language = {en} } @inproceedings{KriegLalaSchoberetal., author = {Krieg, Andreas and Lala, Gjergj and Schober, Fabian and Wiener, Johannes and Paulus, Johannes and K{\"u}chler, Andreas and Zink, Markus H. and Liebschner, Marcus}, title = {FEM model for describing the dielectric behavior of oil-impregnated pressboard under DC stresses}, series = {Papers of 33rd International Scientific Conference "Science in Practice"}, booktitle = {Papers of 33rd International Scientific Conference "Science in Practice"}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:863-opus-2609}, pages = {62 -- 66}, abstract = {According to the worldwide growing demand for electric energy, it is necessary to construct safe and efficient power systems. HVDC (high voltage direct current) applications become more and more important due to larger distances for the energy transportation and the increasing demand for reactive power transportation. Appropriate insulation materials, i.e. mineral oil and pressboard, are widely used in HVDC components, mainly in power transformers though the knowledge about dielectric behavior of oil-impregnated pressboard under DC stresses in time domain is not sufficient. In this paper, a Finite Element Method (FEM) model is presented to describe the electrical conduction behavior of the material by separate consideration of mineral oil and pressboard. With this model the electric potential distribution under DC stress was simulated to analyze polarization and electrical conduction. The model parameters volume ratio as well as angle variations of FEM model are investigated and their influences on the current through the model are evaluated. Furthermore, geometrical and physical parameters are estimated and the results are compared to currents that are measured on oil-impregnated pressboard samples in time domain.}, language = {en} }