TY - CHAP A1 - Volkova, Anna A1 - Schmidhuber, Julian A1 - de Meer, Hermann A1 - Hess, Robin A1 - Schilling, Klaus A1 - Wellhöfer, Anatoli A1 - Zink, Markus T1 - Design and Simulation of LEO Satellite Communication Networks for Reliable Monitoring and Control in Power Systems T2 - The 14th DACH+ Conference on Energy Informatics Y1 - 2025 UR - https://energy.acm.org/eir/design-and-simulation-of-leo-satellite-communication-networks-for-reliable-monitoring-and-control-in-power-systems/ ER - TY - CHAP A1 - Rahimpour, Ebrahim A1 - Ghorbal, Mohammed Bilal A1 - Mirzaei, Hassan Reza T1 - Evaluating the Influence of External Compensators on Chopped Impulse Waves in Power Transformer Testing T2 - 2024 IEEE International Conference on High Voltage Engineering and Applications, Berlin, Germany N2 - Applying lightning impulse tests on high-voltage transformers plays a crucial role in evaluating their insulation system. The performance of the dielectric system in newly produced power transformers must satisfy the requirements of both full and chopped wave tests. To conduct these tests, standard full and chopped impulses are generated using the well-known Marx generator. The wave shape parameters of these impulses must fulfil the requirements that are specified in international standards such as IEC 60076. The excessive voltage collapse rate as well as the high amplitude of the first peak of the resulting overswing following the chopping time, highly stress the dielectric system of the power transformers. To resolve these issues, external elements may be added to the chopping circuit. These additional elements are essential in stabilizing the waveform by preventing excessive voltage collapse rate and controlling the peak of the first swing after chopping. Furthermore, some transformers with high power ratings may possess windings with very low inductance or high capacitance, which can undesirably impact the shape and parameters of the resulting full wave. To address these critical situations and bring the full wave parameters within the allowed limits, engineers in high-voltage laboratories employ some compensators like the Glaninger circuit in impulse circuits. It is important to study the effects of such compensators on chopped impulse parameters. This paper aims to investigate the impact of the mentioned external elements and compensators on the parameters of the chopped wave impulses. Specifically, the study focuses on assessing the influence of these compensators on voltage collapse and the peak amplitude of the first swing after chopping. By analyzing and understanding these effects, researchers and engineers can gain valuable insights into the performance and optimization of lightning impulse tests on power transformers, ultimately contributing to the advancement of high-voltage laboratory practices. KW - Marx impulse generator KW - Lightning impulse test KW - chopped wave KW - Overswing KW - Compensator Y1 - 2024 SN - 979-8-3503-7498-8 U6 - https://doi.org/10.1109/ICHVE61955.2024.10676122 SP - 969 EP - 972 PB - IEEE ER - TY - CHAP A1 - Rahimpour, Ebrahim A1 - Al-Abadi, A. A1 - Gamil, A. T1 - Dynamisches Feuchtigkeitsgleichgewicht in flüssigkeitsgefüllten Transformatoren T2 - 17th Transformer-Life-Management Konferenz, Zeulenroda, Germany, 16-17 September 2024 Y1 - 2024 ER - TY - CHAP A1 - Krieg, Andreas A1 - Lala, Gjergj A1 - Schober, Fabian A1 - Wiener, Johannes A1 - Paulus, Johannes A1 - Küchler, Andreas A1 - Zink, Markus H. A1 - Liebschner, Marcus T1 - FEM model for describing the dielectric behavior of oil-impregnated pressboard under DC stresses T2 - Papers of 33rd International Scientific Conference "Science in Practice" N2 - 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. KW - electrical conduction KW - FEM simultation KW - HVDC KW - polarization KW - oil-impregnated pressboard Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:863-opus-2609 SP - 62 EP - 66 ER - TY - CHAP A1 - Targitay, Deniz A1 - Roth, Lisa A1 - Zink, Markus H. A1 - Küchler, Andreas A1 - Bier, Markus A1 - Kobus, Maja A1 - Geißler, Michael A1 - Schlittler, Balz T1 - An FEM simulation model of oil-pressboard insulating systems for HVDC transformers T2 - 23rd International Symposium on High Voltage Engineering (ISH 2023) N2 - 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. KW - Mineral oil KW - Oil-impregnated pressboard KW - Poisson-Nernst-Planck theory KW - Ion drift KW - Electric current Y1 - 2023 UR - https://doi.org/10.1049/icp.2024.0488 PB - Institution of Engineering & Technology ER - TY - CHAP A1 - Frauenknecht, Dominik A1 - Schweinshaut, Bernd A1 - Raab, Alexander A1 - Mehlmann, Gert A1 - Luther, Matthias A1 - Wiest, Pascal A1 - Heyde, Chris Oliver A1 - Wellhöfer, Anatoli ED - VDE ETG, T1 - Stability Analysis of Converter-Dominated Power Systems by Phasor-Based and Electromagnetic Transient Simulation T2 - 15. VDE ETG/VDI/VDE-GMA-Fachtagung „Netzregelung und Systemführung“ Y1 - 2024 SN - 978-3-8007-6292-7 ER - TY - CHAP A1 - Kobus, Maja T1 - Analysis of Electric-Field-Dependent Polarization of Triglyceride Ester Oil Molecules Using DFTB-MD Simulations T2 - 2025 IEEE International Conference on Dielectric Liquids (ICDL) Y1 - 2025 U6 - https://doi.org/https://doi.org/10.1109/ICDL63868.2025.11068245 SP - 1 EP - 4 PB - IEEE ER - TY - JOUR A1 - Walle Biyazne, Likenesh A1 - Berhanu Tuka, Milkias A1 - Mekonnen Abebe, Yoseph A1 - Wellhöfer, Anatoli T1 - Enhancing MPPT performance of a grid-connected Doubly-Fed induction generator-based wind power plant using hybrid ANFIS-PI control strategy JF - Nature Scientific Reports N2 - This paper focuses on an effective control technique for enhancing the Maximum Power Point Tracking (MPPT) performance of a grid-connected DFIG-based wind power plant under continuously varying wind conditions. However, rapid fluctuations in wind speeds, uncertainties in parameters, and grid disturbances are key challenges to enhancing the MPPT performance capability. Considering these struggles, this study aims to model a modified dynamic DFIG-based wind turbine system and develop a hybrid Adaptive Neuro-Fuzzy Inference System (ANFIS) with a Proportional-Integral (PI) controller on the back-to-back converter at the rotor and grid sides. The actual limited ranges of wind speed and output power generation data of the Adama II wind power plant in Ethiopia are utilized as input and output variables for the ANFIS controller. The simulation results from the latest version of R2024a MATLAB-Simulink software show that the proposed ANFIS-PI reached an MPPT of 2.22 MW compared to the FLC-PI controller attained 2.2 MW using the benchmark as the reference value of 1.561 MW in the PI controller, by improving the maximum power coefficient of 0.5504 compared to 0.5473 using the baseline as the reference value of 0.4109, respectively, at a rated wind speed of 12.5 m/s and an optimal pitch angle of 0°. KW - Adaptive Neuro-Fuzzy inference system KW - Doubly-Fed induction generator KW - MATLAB-Simulink software KW - Maximum power point tracking KW - Proportional-Integral Y1 - 2026 UR - https://doi.org/10.1038/s41598-026-36021-3 VL - 16 ER -