@inproceedings{RahimpourChristianFeseretal., author = {Rahimpour, Ebrahim and Christian, Jochen and Feser, K. and Mohseni, Hossein}, title = {Calculation of the Transfer Function to Diagnose Axial Displacement and Radial Deformation of Transformer Windings}, series = {12th International Symposium on High Voltage Engineering, Bangalore, India, 20-24 August 2001}, volume = {5}, booktitle = {12th International Symposium on High Voltage Engineering, Bangalore, India, 20-24 August 2001}, number = {7-41}, pages = {1199-1202}, language = {en} } @inproceedings{RahimpourChristianFeseretal., author = {Rahimpour, Ebrahim and Christian, Jochen and Feser, K. and Mohseni, Hossein}, title = {Modeling of transformer windings for the calculation of the transfer function for the monitoring of transformers}, series = {15th International Power System Conference, Tehran, Iran, November 2000}, booktitle = {15th International Power System Conference, Tehran, Iran, November 2000}, language = {en} } @book{Rahimpour, author = {Rahimpour, Ebrahim}, title = {Hochfrequente Modellierung von Transformatoren zur Berechnung der {\"U}bertragungsfunktione}, publisher = {Shaker}, address = {Aachen, Germany}, isbn = {3826592271}, language = {de} } @article{GhorbalMirzaeiRahimpour, author = {Ghorbal, Mohammed Bilal and Mirzaei, Hassan Reza and Rahimpour, Ebrahim}, title = {Precise Modeling of Chopped Lightning Impulse Test of Power Transformers}, series = {Electric Power Systems Research}, volume = {230}, journal = {Electric Power Systems Research}, number = {110207}, publisher = {Elsevier}, doi = {10.1016/j.epsr.2024.110207}, abstract = {Performing insulation tests on power transformers is one of the most essential topics in high-voltage laboratories. According to international standards like IEC 60,076, full and chopped wave Lightning Impulse (LI) voltages must be applied to high voltage transformers. Since the wave shape parameters of the applied impulses must comply with the constraints that are specified in these standards, the setting of the impulse generator and test circuit must be modified correctly by test engineers. An accurate computerized simulation method is very desirable to help them accomplish this duty quickly and enhance the outcome results. Therefore, this paper proposes a method that is capable of simulating both Full Wave (FW) and Chopped Wave (CW) impulses in the time domain accurately. In this method, the frequency response of the transformer is measured and then the Vector Fitting (VF) technique is used to obtain its admittance model. Additionally, the transformer's impulse test circuit elements are precisely modelled. Afterwards, by solving the equations of the equivalent circuit in the state-space system, the time domain signals of all state variables are calculated. Finally, the output impulse voltages are computed. Several practical tests are accomplished on two power transformers to ensure the correctness of the proposed method.}, language = {en} } @inproceedings{FilipovićGrčićFrolovJurisicetal., author = {Filipović-Grčić, Bozidar and Frolov, Mikhail and Jurisic, Bruno and Manthe, Thomas and Matveev, Daniil and Rahimpour, Ebrahim}, title = {Consideration of Non-Standard Overvoltages Compared with Standard Overvoltages in Power Transformers}, series = {6th International Colloquium Transformer Research and Asset Management, Split, Croatia}, booktitle = {6th International Colloquium Transformer Research and Asset Management, Split, Croatia}, abstract = {Overvoltages that exist in the power system differ from the standard overvoltages (OVs) waveshape, that are used to test power equipment. In the paper typical OV waveshapes that occurs in the power system are analyzed, using the methods available in the literature: frequency domain severity factor (FDSF), time domain severity factor (TDSF) and the method from IEC 60071-2: 2018, Annex I. General remarks about applicability of these methods are given in the paper. It can be concluded that without the knowledge of transformer design and dielectric strength of an insulation system elements, the reliable estimation of non-standard overvoltages severity cannot be made. The results of the paper are in line with the conclusion of CIGRE WG A2.63: Transformer Impulse Testing.}, language = {en} } @inproceedings{RahimpourGhorbalMirzaei, author = {Rahimpour, Ebrahim and Ghorbal, Mohammed Bilal and Mirzaei, Hassan Reza}, title = {Evaluating the Influence of External Compensators on Chopped Impulse Waves in Power Transformer Testing}, series = {2024 IEEE International Conference on High Voltage Engineering and Applications, Berlin, Germany}, booktitle = {2024 IEEE International Conference on High Voltage Engineering and Applications, Berlin, Germany}, publisher = {IEEE}, isbn = {979-8-3503-7498-8}, doi = {10.1109/ICHVE61955.2024.10676122}, pages = {969 -- 972}, abstract = {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.}, language = {en} } @inproceedings{GhorbalMirzaeiRahimpouretal., author = {Ghorbal, Mohammed Bilal and Mirzaei, Hassan Reza and Rahimpour, Ebrahim and Rabih, S.}, title = {Analyzing the Possibility of Improving Waveform Shape in Lightning Impulse Testing of Distribution Transformers}, series = {28th Electrical Power Distribution Conference, Zanjan, Iran}, booktitle = {28th Electrical Power Distribution Conference, Zanjan, Iran}, pages = {1 -- 5}, language = {en} } @inproceedings{RahimpourAlAbadiGamil, author = {Rahimpour, Ebrahim and Al-Abadi, A. and Gamil, A.}, title = {Dynamisches Feuchtigkeitsgleichgewicht in fl{\"u}ssigkeitsgef{\"u}llten Transformatoren}, series = {17th Transformer-Life-Management Konferenz, Zeulenroda, Germany, 16-17 September 2024}, booktitle = {17th Transformer-Life-Management Konferenz, Zeulenroda, Germany, 16-17 September 2024}, language = {de} } @inproceedings{Rahimpour, author = {Rahimpour, Ebrahim}, title = {Herausforderungen der Blitzstoßspannungspr{\"u}fung an Leistungstransformatoren - {\"U}berblick {\"u}ber die CIGRE Arbeitsgruppe A2.63}, series = {16th Transformer-Life-Management Konferenz}, booktitle = {16th Transformer-Life-Management Konferenz}, language = {de} } @article{GustavsenRahimpour, author = {Gustavsen, B. and Rahimpour, Ebrahim}, title = {High-Frequency Transformer and Reactor Models for Network Studies, Part E: Measurements and transformer design details}, series = {Conseil International des Grands R{\´e}seaux {\´E}lectriques (CIGRE) TB 904}, journal = {Conseil International des Grands R{\´e}seaux {\´E}lectriques (CIGRE) TB 904}, isbn = {978-2-8587-3609-6}, pages = {1 -- 140}, language = {en} }