Center for High Voltage Engeneering and Insulating Systems
The research field of high-voltage engeneering and insulation systems is of central importance in modern industrial society. High voltages or high field strengths in the insulation systems are required for the low-loss transmission of electrical energy as well as for a variety of industrial applications from medical to manufacturing to automotive technology.
High-voltage technology includes the control of high electric field strengths in all types of electrical insulation. The simple basic principle is:
Under all conditions, the electrical stress (i.e. the electrical field strength) must always be smaller than the electrical strength of the insulating media.
The task of high-voltage technology is therefore not to generate electrical discharges, even if these are always impressive for visitors to our laboratory, but rather to prevent them in order to ensure the safe operation of devices and systems.
It is now necessary to further exploit insulation systems for technical and economic reasons. That's why a deep understanding of the materials is essential, which is why research in the area of high-voltage insulation materials and systems has now become very much focused on materials science. The direct cooperation of several laboratories involved in the IEHT is a great advantage. Modern analysis methods such as FTIR or Raman spectroscopy are available in the materials science working group and in the chemical-physical laboratory.
The THWS high-voltage laboratory offers for student training, research and cooperation with industrial partners a partially worldwide unique infrasructure. A more detailed description of the equipment can be found on the laboratory's website.
Thematic Fields
Insulating materials and systems for high-voltage direct current transmission (HVDC)
... because in the future three-phase networks worldwide will reach their performance limits and will have to be networked with high-voltage direct current transmission (HVDC) ...
Research fields:
- Investigation of the electrical conductivity of insulating materials under defined boundary conditions
- Investigation of charge carrier generation and recombination as well as charge carrier transport in insulating liquids
- Measuring space charges with the electro-optical Kerr effect
- Measurement of space charges with the Pulsed Electro Acoustic Method (PEA)
- Multiscale modeling of charge transport in liquid and solid insulating materials
- Quantum chemistry
- Molecular dynamics
- Bipolar Charge Transport Models
- FEM simulation of charge transport in insulating materials and systems
Diagnosis, monitoring and condition assessment
... because the networks of industrialized nations were expanded decades ago, so that the safe operation of systems and devices requires reliable diagnostics of the aging condition ...
Research fields:
- Measurement and analysis of partial discharges, e.g. for HVDC applications
- Use of modern PD measurement technology and fault location detection for online and offline diagnosis
- Spectroscopic material analysis
Insulation systems for electrical machines and power electronic applicationsInsulation systems for electrical machines and power electronic applications
...because the new requirements in the area of electrical machines, such as an increase in efficiency, the use of modern, fast-switching power semiconductors and new insulating materials, are leading to increasing loads on the insulating systems...
Research fields:
- Investigation of the TE activity of engine test specimens
- Investigation of the aging behavior of engine insulation systems
- Investigation of the (aging) behavior of insulating materials at high frequencies
Projects
Modeling, simulation and measurement of electric field strength distributions in insulating fluids under transient and steady-state DC loading of layered insulation systems (EFI-DC)
Management Prof. Zink, Prof. Dr. Kobus
Research partners Siemens Energy Global GmbH & Co. KG, Weidmann Electrical Technology AG
Duration 2018-2025
As a result of the energy transition and the restructuring of energy networks, high-voltage direct current transmission (HVDC) is becoming increasingly important and brings with it increasing demands on operating resources. The insulation systems of HVDC equipment, especially transformers, are of particular interest. The main components of such insulation systems are insulating fluids and oil-impregnated pressboard made of cellulose, which exhibit complex electrical conduction and polarization mechanisms under direct voltage stress that have not yet been studied in depth. Conventional RC circuit models are only partially suitable for the dielectric description of these materials and the mechanisms that occur. Rather, multiphysical modeling approaches are required that take different physical-chemical effects into account. These mainly include the Poisson-Nernst-Planck (PNP) system of equations. However, there has so far been no clear consensus regarding the parameterization when using it and the parameters on which the simulation is based are often only meaningfully estimated or varied empirically.
As part of the EFI-DC project, the layered insulation system will therefore be examined with different DC loads and configurations of the insulation system in order to gain a deeper understanding of the dominant charge carrier phenomena. Additional environmental parameters (temperature, pressure, etc.) can be varied, which can be used to test various hypotheses. The primary measurement methods for verification are the simultaneous measurement of the transient polarization current (PDC measurement) and the stationary and transient field strength in existing transparent areas of the insulating medium. Field and current curves resulting from these measurements can be used to parameterize or verify the existing models. With an accurate model and the understanding gained from it, the design of the insulation system of various equipment under DC load can be designed more effectively in terms of weak points and a potential reduction in the installation space of the transformers, which at the same time significantly increases the competitiveness of HVDC technology.
Elastomers with specific conductivity and their aging behavior (ELSA)
Management Prof. Zink, Prof. Kobus
Research partner Pfisterer contact systems
Duration 2022-2025
Elastomers, among other things, are used as insulating materials in complex insulation systems for cable applications (cable sleeves) in high-voltage direct current (HVDC) transmission. The selection and qualification of suitable materials for specific applications is challenging. In addition to the electrical parameters that are important for the design, knowledge about the aging behavior of these materials also plays a central role. In particular, construction and assembly-related situations in a cable sleeve, such as the "noble joint", or additives (lubricants) required for assembly can significantly influence the service life behavior. The combination or layering of various insulating materials such as silicones or EPDM (ethylene-propylene-diene rubbers) with the XLPE (Cross-linked Polyethylene) used in the cable as part of HVDC also brings with it new challenges for the insulation systems. The electrical conductivity has a decisive influence on the field distribution within the layer insulation system. However, this is significantly influenced by its dependence on various influencing factors such as the ambient temperature, the applied electrical field or production-related defects.
As part of the ELSA project (elastomers with specific conductivity and their aging behavior), different aging mechanisms of different elastomers are being investigated in collaboration with the project partner Pfisterer. By using dielectric diagnostic methods, such as polarization and depolarization measurements or space charge measurements using the PEA method, the condition of the insulating material is assessed over its service life. By additionally interpreting the dielectric properties using spectral investigation methods such as infrared and Raman spectroscopy, which allow information to be drawn about the bonding situation in the polymer, a uniform picture of the aging stage can be obtained.
This newly gained knowledge should make a significant contribution to the better qualification and testing of insulating materials, which should lead to advanced and more reliable fittings.
Conductivity investigation of insulating materials with field strength-dependent behavior (LUISE)
Management Prof. Zink
Internal research partner
Duration 2023-2026
The development of energy transmission with high-voltage direct current (HVDC) is a central element of the energy transition. A particular challenge is the safe design of high-voltage insulation systems, whose task is to safely control the high voltages and field strengths within the equipment. While in applications for alternating voltage the electric field (displacement field) can be controlled by the geometry of the electrodes and interfaces, this is not possible for direct voltage (flow field). The conductivities of the insulating materials determine the field distribution in the insulation system. However, the conductivities of the insulating materials are not only very different from one another, but are also highly dependent on the parameters field strength and temperature, whereas this dependence does not apply to the permittivity, which makes the design in the displacement field easier than in the flow field. During operation of the insulation systems, especially when, for example, the temperature distribution changes or temperature gradients develop, the above-mentioned dependencies can lead to the formation of space or surface charge zones, which can drastically change the field strength distribution in the insulation system, so-called field migration or inversion, see . Figure 1. Under certain circumstances, this can lead to the formation of (partial) discharges, which can then erode the materials and damage the insulation system to the point of total failure. Such problems occur not only in the insulation systems of HVDC equipment, but also, for example, in high-tech applications with high direct voltage, such as fundamental physics, semiconductor technology or microscopy. An innovative approach to improve the problems described lies in the use of so-called field grading materials (FGM) with a specifically adjusted or even field strength-dependent electrical conductivity. With these materials, areas with higher field strength can be automatically relieved and the field distribution in the insulation system can be evened out. Such materials are based on a carrier material, e.g. varnish or epoxy resin, in which filling materials (e.g. silicon carbides or metal oxides) are embedded, which show a field strength-dependent, varistor-like conductivity behavior.
Measurement of Motorettes (MEMO)
Management Prof. Zink, Prof. Rahimpour
Research partner NN
Duration 2023-2024
The transformation of the automotive industry towards fully electric vehicles brings with it various challenges in the design and development of individual components. Due to ever-increasing electrical consumers, the need for high voltages in the on-board electrical system is increasing in order to keep currents low and thus enable economical design of the machines. This results in a high electrical load on the insulating materials in the drive train, which is why proven insulation systems are often no longer sufficient. In order to ensure reliable operation over the service life in the future, it is important to examine the aging behavior of the insulation systems.
In the MEMO research project, the aging mechanisms under different types of stress are to be investigated in order to gain knowledge about the dominant aging factors. The accelerated aging tests take place on complete stators and motor formats with various insulation systems. In order to evaluate the aging condition of the test specimens in the individual aging stages, various non-destructive dielectric measurements from high-voltage technology are used. Among other things, the measurement of the insulation resistance (PDC measurement), the loss factor, the partial discharge activity at surge and alternating voltage as well as the frequency domain measurement (FDS) are used to determine the aging condition. If necessary, additional breakdown tests (HiPot) are used to determine the degradation of the insulation systems.
The characteristic values resulting from the tests should be used to parameterize a service life model. Particular attention is also paid to the partial discharge behavior of the test specimens in different aging states, which will be investigated using phase-resolved partial discharge analysis (PRPDA) and pulse sequence analysis (PSA). This serves to further understand the aging mechanisms of the insulation systems and offers the cooperation partner the opportunity to continue to guarantee the usual and required reliability. The results of the investigations show the limits of the insulation systems and offer a comparison with each other. In addition, the tests used can be used in the qualification and manufacturing process of a new product.
Contact
Contact
Prof. Dr. Ebrahim Rahimpour
97421 Schweinfurt
On appointment
Electrical energy supply
High voltage engineering
Head of laboratory for electrical energy supply
Head of Center for High Voltage Technology and Insulation Systems
Teaching Areas
Current courses
- Hochspannungsisolierwerkstoffe und -systeme (Universität Würzburg, Masterstudiengang Funktionswerkstoffe), Sommersemester
- Electrical Engineering 1 (IBE 4. Semester), Sommersemester
- Elektrotechnik (BWT 2. Semester), Sommersemester
- Grundlagen der Elektrotechnik (BTM 4. Semester), Sommersemester
- Elektrotechnik / Elektronik (BM 1. Semester), Sommersemester & Wintersemester
- Energie- und Antriebstechnik (BWW 5. - 7. Semester), Wintersemester
- Energy and Drives (IBE 5. - 7. Semester), Wintersemester
- Praktikum Hochspannungstechnik (BET 5. Semester), Wintersemester
- Praktikum Messtechnik (BET 1. Semester), Wintersemester
Publications
PUBLICATIONS: JOURNALS / CONFERENCES / BOOKS
JOURNAL PAPERS
1. B. Gustavsen, E. Rahimpour, et. al., „High-Frequency Transformer and Reactor Models for Network Studies, Part A: White-Box Models“, CIGRE TB 900, ISBN: 978-2-85873605-8, pp. 1-203, April 2023
2. B. Gustavsen, E. Rahimpour, et. al., „High-Frequency Transformer and Reactor Models for Network Studies, Part B: Black-Box Models“, CIGRE TB 901, ISBN: 978-2-85873606-5, pp. 1-88, April 2023
3. B. Gustavsen, E. Rahimpour, et. al., „High-Frequency Transformer and Reactor Models for Network Studies, Part C: Grey Box Models“, CIGRE TB 902, ISBN: 978-2-85873607-2, pp. 1-102, April 2023
4. B. Gustavsen, E. Rahimpour, et. al., „High-Frequency Transformer and Reactor Models for Network Studies, Part D: Model interfacing and specifications“, CIGRE TB 903, ISBN: 978-2-85873608-9, pp. 1-43, April 2023
5. B. Gustavsen, E. Rahimpour, et. al., „High-Frequency Transformer and Reactor Models for Network Studies, Part E: Measurements and transformer design details“, CIGRE TB 904, ISBN: 978-2-85873609-6, pp. 1-140, April 2023
6. R. Aghmasheh, V. Rashtchi and E. Rahimpour, „Gray Box Modeling of Power Transformer Windings based on Design Geometry and Particle Swarm Optimization Algorithm“, IEEE Transactions on Power Delivery, Vol.33, No.5, pp. 2384-2393, February 2018
7. E. Rahimpour, V. Rashtchi and R. Aghmasheh, „Transiente Vorgänge: Identifikation der Induktivität mit der Kurvenanpassung“, EW: das Magazin für die Energie Wirtschaft, pp. 48-50, December 2017
8. R. Aghmasheh, V. Rashtchi and E. Rahimpour, „Gray Box Modeling of Power Transformer Windings for Transient Studies“, IEEE Transactions on Power Delivery, Vol.32, No.5, pp. 2350-2359, January 2017
9. S. E. Zirka, Y. I. Moroz and E. Rahimpour, „Towards a Transformer Transient Model as a Lumped-Distributed Parameter System“, COMPEL, Vol.36, No.3, pp. 741-750, January 2017
10. V. Behjat, M. Mahvi and E. Rahimpour, „New Statistical Approach to Interpret Power Transformer Frequency Response Analysis: Non-Parametric Statistical Methods“, IET Science, Measurement & Technology, Vol.10, No.4, pp. 364-369, July 2016
11. M. Bigdeli, D. Azizian and E. Rahimpour, „An Improved Big Bang-Big Crunch Algorithm for Estimating Three-Phase Induction Motors Efficiency“, Journal of Operation and Automation in Power Engineering, Vol.4, No.1, pp. 83-92, 2016
12. B. Gustavsen, E. Rahimpour, et. al., „Electrical Transient Interaction between Transformer and the Power System, Part I: Expertise“, CIGRE TB 577A, ISBN: 978-2-85873272-2, pp. 1-175, April 2014
13. B. Gustavsen, E. Rahimpour, et. al., „Electrical Transient Interaction between Transformer and the Power System, Part II: Case Studies“, CIGRE TB 577B, ISBN: 978-2-85873272-2, pp. 1-123, April 2014
14. B. Gustavsen, E. Rahimpour, et. al., „Electrical Transient Interaction between Transformer and the Power System“, Electra, No.273, pp. 96-103, April 2014
15. J. Smajic, R. Obrist, M. Rüegg, B. Cranganu-Cretu, C. Roy, B. Weber and E. Rahimpour, „Lightning Impulse Modeling and Simulation of Dry-Type and Oil-Immersed Power- and Distribution Transformers“, Journal of Energy: Energija, Vol.63, No.1-4, 2014
16. A. Lotfi and E. Rahimpour, „Optimum Design of Core Blocks and Analyzing the Fringing Effect in Shunt Reactors with Distributed Gapped-Core“, Electric Power Systems Research, Elsevier, Vol.101, pp. 63-70, August 2013
17. M. Bigdeli, E. Rahimpour and D. Azizian, „Combination of Mathematical Indices and Probabilistic Neural Network to Detect the Type of Winding Fault in Transformers“, Journal of Electrical Systems, Vol.9, No.2, pp. 167-178, June 2013
18. M. Bigdeli, M. Vakilian and E. Rahimpour, „A Probabilistic Neural Network Classifier-Based Method for Transformer Winding Fault Identification through its Transfer Function Measurement“, European Transactions on Electrical Power (ETEP), Vol.23, No.3, pp. 392-404, April 2013
19. D. Gorzin, E. Rahimpour and A. Gorzin „A New Approach on Fault Discrimination for Diagnosis of Two-Winding Transformers using Transfer Function Method“, International Review on Modelling and Simulations, Vol.5, No.5, pp. 1987-1994, October 2012
20. M. Bigdeli, M. Vakilian and E. Rahimpour, „Transformer Winding Faults Classification based on Transfer Function Analysis by Support Vector Machine“, IET Electric Power Applications, Vol.6, No.5, pp. 268-276, May 2012
21. M. Bigdeli and E. Rahimpour, „Optimized Modeling of Transformer in Transient State with Genetic Algorithm“, International Journal of Energy Engineering, Vol.2, No.3, pp. 108-113, May 2012
22. V. Rashtchi, E. Rahimpour and H. Shahrouzi, „Model Reduction of Transformer Detailed R-C-L-M Model using the Imperialist Competitive Algorithm“, IET Electric Power Applications, Vol.6, No.4, pp. 233-242, April 2012
23. M. Bigdeli, M. Vakilian and E. Rahimpour, „Comparison of Transfer Functions using Estimated Rational Functions to Detect Winding Mechanical Faults in Transformers“, Archives of Electrical Engineering, Vol.61, No.1, pp. 85-99, March 2012
24. M. Bigdeli, M. Vakilian, E. Rahimpour and D. Azizian, „Theoretical and Experimental Investigation of Transformer Winding Fault Detection using Comparison of Transfer Function Coefficients“, ECTI Transactions on Electrical Engineering, Electronics, and Communications (ECTI - EEC), Vol.10, No.1, pp. 107-113, February 2012
25. K. Pourhossein, G. B. Gharehpetian, E. Rahimpour and B. N. Araabi, „A Vector-based Approach to Discriminate Radial Deformation and Axial Displacement of Transformer Winding and Determine Defect Extent“, Electric Power Components and Systems, Taylor & Francis, Vol.40 (2012), No.6, pp. 597-612
26. E. Rahimpour, V. Rashtchi and H. Shahrouzi, „Applying Artificial Optimization Methods for Transformer Model Reduction of Lumped Parameter Models“, Electric Power Systems Research, Elsevier, Vol.84 (2012), No.1, pp. 100-108
27. K. Pourhossein, G. B. Gharehpetian, E. Rahimpour and B. N. Araabi, „A Probabilistic Feature to Determine Type and Extent of Winding Mechanical Defects in Power Transformers“, Electric Power Systems Research, Elsevier, Vol.82 (2012), No.1, pp. 1-10
28. E. Rahimpour, „Fehlererkennung bei Transformatoren: Vergleichen der Übertragungsfunktionen“, EW: das Magazin für die Energie Wirtschaft, Vol.110, No.24, pp. 30-32, November 2011
29. E. Ataei, R. Afshari and E. Rahimpour, „Design and Implementation of an Intelligent Solar Power Plant based on Fuzzy Logic“, International Review of Automatic Control, Vol.4, No.6, pp. 938-942, November 2011
30. V. Rashtchi, E. Rahimpour and S. Fazli, „Genetic Algorithm Application to Detect Broken Rotor Bar in Three Phase Squirrel Cage Induction Motors“, International Review of Electrical Engineering, Vol.6, No.5, pp. 2286-2292, October 2011
31. V. Rashtchi and E. Rahimpour, „Detection and Localization of Turn-to-Turn Short Fault in Power Transformers by Analyzing of Transfer Function using an Artificial Neural Network“, International Review on Modelling and Simulations, Vol.4, No.5, pp. 2159-2163, October 2011
32. E. Rahimpour and S. Tenbohlen, „Fault Diagnosis of Actual Large-Power High-Voltage Windings using Transfer Function Method“, Archives of Electrical Engineering, Vol.60, No.3, pp. 269-281, September 2011
33. V. Rashtchi, E. Rahimpour and J. Mirzaei, „Using Particle Swarm Optimization Algorithm for Transformer Transient Study“, International Review of Electrical Engineering, Vol.6, No.3, pp. 1174-1180, May-June 2011
34. M. Bigdeli, M. Vakilian and E. Rahimpour, „A New Method for Detection and Evaluation of Winding Mechanical Faults in Transformer through Transfer Function Measurements“, Advances in Electrical and Computer Engineering, Vol.11, No.2, pp. 23-30, May 2011
35. R. Afshari and E. Rahimpour, „Design and Implementation of a Machine to Increase the Life of Oil Immersed Transformers by Automatic Restoration of Silica Gel“, Recent Patents on Electrical Engineering, Vol.4, No.2, pp. 108-113, May 2011
36. E. Rahimpour, V. Rashtchi and H. Shahrouzi, „Hochfrequenz-Modellierung: Identifikation von Modellparametern der Leistungstransformatoren“, EW: das Magazin für die Energie Wirtschaft, Vol.110, No.4, pp. 44-47, February 2011
37. V. Rashtchi, E. Rahimpour and H. Fotoohabadi, „Parameter Identification of Transformer Detailed Model based on Chaos Optimization Algorithm“, IET Electric Power Applications, Vol.5, No.2, pp. 238-246, February 2011
38. M. Bigdeli, E. Rahimpour and M. Khatibi, „Transient-State Modeling of Distribution Transformers“, International Review on Modelling and Simulations, Vol.4, No.1, pp. 295-302, February 2011
39. E. Rahimpour, M. Jabbari and S. Tenbohlen, „Mathematical Comparison Methods to Assess Transfer Functions of Transformers to Detect Different Types of Mechanical Faults“, IEEE Transactions on Power Delivery, Vol.25, No.4, pp. 2544-2555, October 2010
40. E. Rahimpour and S. Tenbohlen, „Experimental and Theoretical Investigation of Disc Space Variation in Real High-Voltage Windings using Transfer Function Method“, IET Electric Power Applications, Vol.4, No.6, pp. 451-461, July 2010
41. V. Rashtchi, H. Shayeghi, M. Mahdavi, A. Kimiyaghalam and E. Rahimpour, „Using an Improved PSO Algorithm for Parameter Identification of Transformer Detailed Model“, International Journal of Electrical Power and Energy Systems Engineering, Vol.1, No.3, pp. 138-144, January 2008
42. E. Rahimpour and D. Azizian, „Analysis of Temperature Distribution in Cast-Resin Dry-Type Transformers“, Archiv für Elektrotechnik (Electrical Engineering), Vol.89 (2007), No.4, pp. 301-309
43. E. Rahimpour, M. Barati and M. Schäfer, „An Investigation of Parameters Affecting the Temperature Rise in Windings with Zigzag Cooling Flow Path“, Applied Thermal Engineering, Elsevier, Vol.27 (2007), No.11-12, pp. 1923-1930
44. E. Rahimpour, V. Rashtchi and M. Pesaran, „Parameter Identification of Deep-Bar Induction Motors using Genetic Algorithm“, Archiv für Elektrotechnik (Electrical Engineering), Vol.89 (2007), No.7, pp. 547-552
45. E. Rahimpour, V. Rashtchi and E. M. Rezapour, „Parameter Tuning of Transformer by using of Genetic Algorithm“, Journal of Faculty of Engineering of Tehran University, Vol.41 (2007), No.5, pp. 615-622
46. E. Rahimpour and D. Gorzin, „A New Method for Comparing the Transfer Function of Transformers in order to Detect the Location and Amount of Winding Faults“, Archiv für Elektrotechnik (Electrical Engineering), Vol.88 (2006), No.5, pp. 411-416
47. V. Rashtchi, E. Rahimpour and E. M. Rezapour, „Using a Genetic Aalgorithm for Parameter Identification of Transformer R-L-C-M Model“, Archiv für Elektrotechnik (Electrical Engineering), Vol.88 (2006), No.5, pp. 417-422
48. E. Rahimpour and N. Hamidi, „The Effects of Axial Displacement of Transformer Windings on Impulse and Transferred Voltage Distribution“, Electric Power Systems Research, Elsevier, Vol.76 (2006), No.6-7, pp. 509-514
49. E. Rahimpour, J. Christian, K. Feser and H. Mohseni, „Transfer Function Method to Diagnose Axial Displacement and Radial Deformation of Transformer Windings“, IEEE Transactions on Power Delivery, Vol.18, No.2, pp. 493-505, April 2003
50. E. Rahimpour, H. Lesani, H. Mohseni, J. Christian and K. Feser, „Calculation of Parameters for the Detailed Modelling of Deformed Windings in Frequency Response Analysis“, Journal of Faculty of Engineering of Tehran University, Vol.36 (2003), No.4, pp. 505-516
51. E. Rahimpour, J. Christian, K. Feser and H. Mohseni, „Ability of Transfer Function Method to Diagnose Axial Displacement of Transformer Windings“, European Transactions on Electrical Power (ETEP), Vol.12, No.3, pp. 225-234, May/June 2002
52. E. Rahimpour, J. Christian, K. Feser und H. Mohseni, „Die Fähigkeit eines detaillierten Modells zur Diagnose axialer Verschiebungen in Transformatorwicklungen mit Hilfe von Übertragungsfunktionen“, Archiv für Elektrotechnik (Electrical Engineering), Vol.83 (2001), No.1-2, pp. 55-61
53. E. Rahimpour, J. Christian, K. Feser und H. Mohseni, „Modellierung der Transformatorwicklung zur Berechnung der Übertragungsfunktion für die Diagnose von Transformatoren“, Elektrie, Berlin 54 (2000), No.1-2, pp.18-30
CONFERENCE PAPERS
1. B. Filipović-Grčić, M. Frolov, B. Jurisic, T. Manthe, D. Matveev, and E. Rahimpour, „Consideration of Non-Standard Overvoltages Compared with Standard Overvoltages in Power Transformers“, 6th International Colloquium Transformer Research and Asset Management, Split, Croatia, 29 November – 2 December 2023, Paper No. 144
2. E. Rahimpour, „Herausforderungen der Blitzstoßspannungsprüfung an Leistungstransformatoren - Überblick über die CIGRE Arbeitsgruppe A2.63“, 16th Transformer-Life-Management Konferenz, Schweinfurt, Germany, 18-19 September 2023
3. E. Rahimpour, V. Rashtchi and R. Aghmasheh, “Estimation of Number of Model Units in Transformer Detailed RCLM Model based on Terminal Measurement in the Case of Unavailable Design Data”, 21st International Symposium on High Voltage Engineering, Budapest, Hungary, 26-30 August 2019, Paper No. 721
4. E. Rahimpour, V. Rashtchi and R. Aghmasheh, „Dimension Estimation of Transformer Windings based on Frequency Response Measurement“, 21st International Symposium on High Voltage Engineering, Budapest, Hungary, 26-30 August 2019, Paper No. 720
5. S. Tenbohlen, M. Tahir, E. Rahimpour, B. Poulin and S. Miyazaki, „A New Approach for High Frequency Modelling of Disc Windings“, CIGRE 2018, Paper No. A2-214, August 2018
6. E. Rahimpour, V. Rashtchi and R. Aghmasheh, „Estimation of Series Resistance of Transformer Winding for Fast Transient Analysis“, 20th International Symposium on Electrical Apparatus and Technologies, Bourgas, Bulgaria, 3-6 June 2018
7. E. Rahimpour, V. Rashtchi and R. Aghmasheh, „Parameters Estimation of Transformers Gray Box Model“, IEEE International Conference on Modern Electrical and Energy Systems, Kremenchuk, Ukraine, 15-17 November 2017
8. S. E. Zirka, Y. I. Moroz and E. Rahimpour, „Towards a Transformer Transient Model as a Lumped-Distributed Parameter System“, 24th Symposium on Electromagnetic Phenomena in Nonlinear Circuits, Helsinki, Finland, 28 June – 1 July 2016
9. J. Smajic, R. Obrist, M. Rüegg, B. Cranganu-Cretu, C. Roy, B. Weber and E. Rahimpour, „Lightning Impulse Modeling and Simulation of Dry-Type and Oil-Immersed Power- and Distribution Transformers“, 3rd CIGRE International Colloquium Transformer Research and Asset Management, Split, Croatia, 15-17 October 2014
10. S. Behzadpoor, V. Rashtchi, M. Hashemi and E. Rahimpour, „Using Imperialist Competitive Algorithm for Parameter Identification of Transformer R-L-C-M Model“, International Transformer Conference and Exhibition, Paper No. 14, Tehran, Iran, 16-17 September 2014
11. A. Lotfi, H. K. Hoidalen, N. Chiesa and E. Rahimpour, „Calculation of Off-Core Inductance in Dual-Circuit Model of Transformer“, Power Systems Computation Conference, Wroclaw, Poland, 18-22 August 2014
12. M. Bigdeli, M. Vakilian and E. Rahimpour, „Detection of Winding Faults in Power Transformers using Transfer Function Method based on Probabilistic Neural Networks“, 20th Iranian Conference on Electrical Engineering, Tehran, Iran, 15-17 May 2012
13. K. Pourhossein, G. B. Gharehpetian and E. Rahimpour, „Determining Intensity of Radial Deformation and Axial Displacement of Transformer Winding using Angular Proximity Index“, 26th International Power System Conference, Paper No. 11-E-TRN-1315, Tehran, Iran, 31 October - 2 November 2011
14. K. Pourhossein, G. B. Gharehpetian and E. Rahimpour, „Extracting Indices to Detect Mechanical Fault Extent in Transformers: A Probabilistic Approach“, 26th International Power System Conference, Paper No. 11-E-TRN-1273, Tehran, Iran, 31 October - 2 November 2011
15. M. Bigdeli, M. Vakilian, E. Rahimpour and D. Azizian, „A New Method for Determination the Type of Winding Fault in Transformer using Transfer Function Measurement“, Conference: Soft magnetic material (SMM20), Kos, Greece, September 2011
16. V. Rashtchi, E. Rahimpour and H. Shahrouzi, „Application of Adaptive Step Length Bacterial Foraging Algorithm for Parameter Identification of Transformer Detailed Model“, 17th International Symposium on High Voltage Engineering, Hannover, Germany, 22-26 August 2011, Paper No. B-027
17. V. Rashtchi, E. Rahimpour and H. Shahrouzi, „Transformer Model Reduction of Lumped Parameters Models using Imperialist Competitive Algorithm“, 17th International Symposium on High Voltage Engineering, Hannover, Germany, 22-26 August 2011, Paper No. B-028
18. M. Bigdeli, M. Vakilian, E. Rahimpour and D. Azizian, „Transformer Winding Diagnosis using Comparison of Transfer Function Coefficients“, 8th International Conference by Electrical Engineering / Electronics, Computer, Telecommunications and Information Technology Association (ECTI-CON), Khon Kaen, Thailand, 17-19 May 2011
19. K. Pourhossein, G. B. Gharehpetian and E. Rahimpour, „Buckling Severity Diagnosis in Power Transformer Windings using Euclidean Distance Classifier“, 19th Iranian Conference on Electrical Engineering, Tehran, Iran, 17-19 May 2011
20. K. Pourhossein, G. B. Gharehpetian and E. Rahimpour, „Axial Displacement Extent Determination in Power Transformer Windings using an Adjustable Index“, 25th International Power System Conference, Paper No. 10-F-TRN-1216, Tehran, Iran, 8-10 November 2010
21. K. Pourhossein, G. B. Gharehpetian and E. Rahimpour, „Discrimination of Axial Displacement and Radial Deformation in Power Transformer Windings using Manhattan Distance Function“, 25th International Power System Conference, Paper No. 10-F-TRN-1217, Tehran, Iran, 8-10 November 2010
22. M. Bigdeli, D. Azizian, H. Bakhshi and E. Rahimpour, „Identification of Transient Model Parameters of Transformer using Genetic Algorithm“, IEEE International Conference on Power System Technology (POWERCON), Zhejiang, China, 24-28 October 2010
23. M. Faridi, M. Kharezy, E. Rahimpour, H. R. Mirzaei and A. Akbari, „Localization of Turn-to-Turn Fault in Transformers using Artificial Neural Network and Winding Transfer Function“, 10th IEEE International Conference on Solid Dielectrics (ICSD), Potsdam, Germany, 4-9 July 2010
24. M. Bigdeli and E. Rahimpour, „Estimation of Simplified Transient Model Parameters using Genetic Algorithm“, 18th Iranian Conference on Electrical Engineering, Isfahan, Iran, 11-13 May 2010
25. M. Bigdeli, M. Vakilian and E. Rahimpour, „A New Method of Comparing Transfer Functions based on Vector Fitting to Detect Winding Faults in Power Transformers“, 18th Iranian Conference on Electrical Engineering, Isfahan, Iran, 11-13 May 2010
26. M. Bigdeli, M. Vakilian and E. Rahimpour, „Analysis of the Methods used to Compare Transfer Functions in order to Fault Diagnostics in Power Transformer Windings“, 24th International Power System Conference, Paper No. 09-F-TRN-0111, Tehran, Iran, November 2009
27. A. Mousavi and E. Rahimpour, „Determining the Traveling Wave Coefficients in Power Transformers using Detailed Model“, IEEE Symposium on Industrial Electronics and Applications (ISIEA), Kuala Lumpur, Malaysia, pp. 349-354, 4-6 October 2009
28. D. Azizian, B. Ahmadzadeh and E. Rahimpour, „The Main Parameters Affecting Temperature of Cast-Resin Transformers“, 12th Iranian Student Conference on Electrical Engineering, Tabriz, Iran, 7-9 August 2009
29. A. Rahimpour, V. Rashtchi and E. Rahimpour, „Study of Turn-to-Turn Short Circuit in High-Voltage Windings using Transfer Function Method“, 17th Iranian Conference on Electrical Engineering, Tehran, Iran, May 2009
30. E. Rahimpour and M. Bigdeli, „Simplified Transient Model of Transformer based on Geometrical Dimensions used in Power Network Analysis and Fault Detection Studies“, IEEE Second International Conference on Power Engineering, Energy and Electrical Drives, Lisbon, Portugal, Paper No. 33, pp. 375-380, 18-20 March 2009
31. E. Rahimpour, M. Mousavi and S. Tenbohlen, „New Hybrid Method based on Correlation Coefficients and Artificial Neural Networks to Detect the Fault in Transformers“, 23rd International Power System Conference, Paper No. 49-F-TRN-734, Tehran, Iran, October 2008
32. V. Rashtchi, J. Mirzaei, A. Kimiyaghalam and E. Rahimpour, „A Particle Swarm Optimization Method to Parameter Identification of Detailed Model“, 23rd International Power System Conference, Paper No. 98-F-TRN-807, Tehran, Iran, October 2008
33. E. Rahimpour, M. Mahdavi and A. Marami, „Identification of Three-Phase Double-Fed Induction Motor Parameters by Evolutionary Techniques“, 11th Iranian Student Conference on Electrical Engineering, Zanjan University, Zanjan, Iran, 27-29 August 2008
34. E. Rahimpour, M. Jabbari and S. Tenbohlen, „Determining the Location and Amount of Disc Space Variation in Transformer Windings using Correlation Factors“, 16th Iranian Conference on Electrical Engineering, Tehran, Iran, May 2008
35. E. Rahimpour, M. Mousavi and S. Tenbohlen, „Detection of Disc Space Variations in Transformer Windings by Evaluation of Current and Voltage Waveforms using Correlation Factors“, 13th Electrical Power Distribution Conference, Zibakenar, Iran, 2008
36. V. Rashtchi, H. Fotoohabadi and E. Rahimpour, „Parameter Identification of Power Transformers using Chaos Mathematics“, 22nd International Power System Conference, Paper No. 98-F-TRN-581, Tehran, Iran, November 2007
37. E. Rahimpour, M. Jabbari and S. Tenbohlen, „Detection the Location and Amount of Disc Space Variation in Power Transformer using Weight Functions“, 22nd International Power System Conference, Paper No. 49-F-TRN-446, Tehran, Iran, November 2007
38. E. Rahimpour, M. Feizi, A. Nateghi and K. Miralikhani, „Determining the Parameters of RLCM Detailed Model of Cast-Resin Dry-Type Transformers using FEM“, 22nd International Power System Conference, Paper No. 98-F-TRN-969, Tehran, Iran, November 2007
39. K. Valipour, M. Bathaee, E. Rahimpour and K. Miralikhani, „Fast Transient Analysis of High Voltage Winding of Cast-Resin Dry-Type Transformer and Comparison with Oil Distribution Transformer“, 22nd International Power System Conference, Paper No. 98-F-TRN-158, Tehran, Iran, November 2007
40. E. Rahimpour and S. Tenbohlen, „A Mathematical Model to Investigate Disc Space Variation in Power Transformer using Transfer Function Analysis“, 15th International Symposium on High Voltage Engineering, Ljubljana, Slovenia, 27-31 August 2007, Paper No. T7-146
41. E. Rahimpour and A. Mousavi, „Determining the Frequency Characteristic of Transformer Reflection and Transmission Coefficients using Detailed Model“, 15th International Symposium on High Voltage Engineering, Ljubljana, Slovenia, 27-31 August 2007, Paper No. T2-66
42. E. Rahimpour, M. Faridi, A. Akbari and K. Miralikhani, „Using the Artificial Neural Network (ANN) for Detection and Localization of Turn to Turn Fault in Distribution Transformers“, 15th Iranian Conference on Electrical Engineering, Tehran, Iran, May 2007
43. E. Rahimpour and M. Bigdeli, „Simplified Transient Model of Transformer based on Geometrical Dimensions for Power Network Analysis“, 15th Iranian Conference on Electrical Engineering, Tehran, Iran, May 2007
44. E. Rahimpour and M. Bigdeli, „A Proper Black Box Model for Analyzing Transient Phenomenon in Distribution Transformers“, 15th Iranian Conference on Electrical Engineering, Tehran, Iran, May 2007
45. D. Azizian and E. Rahimpour, „Temperature Prediction in Cast-Resin Dry-Type Transformers Due to Non-Linear Loads“, 15th Iranian Conference on Electrical Engineering, Tehran, Iran, May 2007
46. D. Azizian and E. Rahimpour, „The Effects of Different Parameters and Conditions on the Temperature Distribution of Cast-Resin Transformers“, 21st International Power System Conference, Tehran, Iran, November 2006
47. E. Rahimpour and D. Azizian, „Steady State Thermal Modeling of Cast-Resin Dry-Type Transformers“, 20th International Power System Conference, Tehran, Iran, November 2005
48. E. Rahimpour and N. Hamidi, „The Effects of Axial Displacement of Transformer Windings on Impulse and Transferred Voltage Distribution“, 13th Iranian Conference on Electrical Engineering, Zanjan, Iran, Vol. 4, pp. 413-418, May 2005
49. E. Rahimpour and M. Zeinali, „Different Methods of Elimination or Mitigation of Transformer Inrush Current“, 13th Iranian Conference on Electrical Engineering, Zanjan, Iran, Vol. 4, pp. 510-515, May 2005
50. E. Rahimpour, D. Gorzin and H. Kaiumarzy, „A New Method for Comparing the Transfer Function of Transformers in order to Detect the Location of Winding Faults“, 13th Iranian Conference on Electrical Engineering, Zanjan, Iran, Vol. 4, pp. 368-373, May 2005
51. M. Fathi, E. Rahimpour and K. Zaree, „Modeling of Magnetic Saturation of the Three Phase Induction Motor using the SIMULINK Software Package of MATLAB“, 6th Power System Conference, Tehran, Iran, October 2004
52. E. Rahimpour, H. Lesani, H. Mohseni, J. Christian and K. Feser, „Simulation and Analysis of the Transfer Function to Diagnose Mechanical faults in Transformer Windings“, 10th Iranian Conference on Electrical Engineering, Tabriz, Iran, Vol. 4, pp. 654-659, May 2002
53. E. Rahimpour, J. Christian, K. Feser, H. Lesani and H. Mohseni, „Mathematical Model for Transformer Winding to Diagnose radial Deformation“, 16th International Power System Conference, Tehran, Iran, November 2001
54. E. Rahimpour, J. Christian, K. Feser and H. Mohseni, „Ability of a Detailed Transformer Model to Diagnose Radial Deformation of Windings“, International Conference on Advances in Processing, Testing and Application of Dielectric Materials, Wroclaw, Poland, 17-19 September 2001
55. E. Rahimpour, J. Christian, K. Feser and H. Mohseni, „Calculation of the Transfer Function to Diagnose Axial Displacement and Radial Deformation of Transformer Windings“, 12th International Symposium on High Voltage Engineering, Bangalore, India, Vol.5, No.7-41, pp. 1199-1202, 20-24 August 2001
56. E. Rahimpour, J. Christian, K. Feser and H. Mohseni, „Modeling of Transformer Windings for the Calculation of the Transfer Function for the Monitoring of Transformers“, 15th International Power System Conference, Tehran, Iran, November 2000
57. H. Mohseni and E. Rahimpour, “Calculation of Impulse Voltage Distribution in Transformer Windings”, 5th Iranian Conference on Electrical Engineering, Tehran, Iran, May 1997 (in Persian)
BOOKS
1. E. Rahimpour, „Hochfrequente Modellierung von Transformatoren zur Berechnung der Übertragungsfunktionen“, Shaker Verlag, ISBN: 3826592271, Aachen, Germany, 2001 (Dissertation)
Career
Academic Curriculum Vitae
Since April 2023: Professor for electrical power supply and power system components at the THWS
10/2008 – 03/2023: R&D principal engineer and project leader, ABB AG and Hitachi Energy, Bad Honnef
06/2007 – 09/2008: Academic member at the Institute of Power Transmission and High Voltage Technology (IEH) of Stuttgart University
05/2002 – 05/2007: Associate Professor at the Zanjan University, Zanjan
04/1996 – 04/2002: Ph.D. student at the Institute of Power Transmission and High Voltage Technology (IEH) of Stuttgart university and at the Engineering Faculty of Tehran University
06/1995 – 03/1996: Lecturer at Zanjan University, Zanjan
10/1993 - 05/1995: Master’s degree at the Engineering Faculty of Tehran University
10/1989 - 09/1993: Bachelor’s degree at the Engineering Faculty of Tabriz University
Additional Information
Activities in international committees
IEEE Senior Member
CIGRÉ Member
IEC Member
Full member of CIGRÉ Working Group A2/C4.39 "Electrical transient interaction between transformers and the power system"
Full member of CIGRÉ Working Group A2/C4.52 "High-frequency transformer models for non-standard waveforms"
Convenor of CIGRÉ Working Group A2.63 "Transformer impulse testing"
Full member of IEC MT-60076-4 "Guide to the lightning impulse and switching impulse testing - Power transformers and reactors"