Author
D. Susa
Other affiliations: University of Helsinki
Bio: D. Susa is an academic researcher from Helsinki University of Technology. The author has contributed to research in topics: Distribution transformer & Transformer. The author has an hindex of 5, co-authored 6 publications receiving 444 citations. Previous affiliations of D. Susa include University of Helsinki.
Papers
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TL;DR: In this article, the authors introduce hot-spot and top-oil temperature thermal models for more accurate temperature calculations during transient states based on data received in a normal heat run test (i.e., the top oil in the tank of the transformer and the average winding-to-average oil gradient).
Abstract: The aim of this paper is to introduce hot-spot and top-oil temperature thermal models for more accurate temperature calculations during transient states based on data received in a normal heat run test (i.e., the top oil in the tank of the transformer and the average winding-to-average oil gradient). Oil viscosity changes and loss variation with temperature are taken into account. The new thermal models will be validated using experimental (fiber-optic test) results obtained at varying load current on a 250-MVA-ONAF-cooled unit, a 400-MVA-ONAF-cooled unit and a 605-MVA-OFAF-cooled unit. The results are also compared with the IEEE-Loading guide (1995) Annex G method.
285 citations
06 Jun 2004
TL;DR: In this paper, the authors introduce hot-spot and top-oil temperature thermal models for more accurate temperature calculations during transient states, based on data received in a normal heat run test (i.e. the top oil in the tank of transformer and the average winding-to-average oil gradient).
Abstract: Summary form only given. The aim of This work is to introduce hot-spot and top-oil temperature thermal models for more accurate temperature calculations during transient states, based on data received in a normal heat run test (i.e. the top oil in the tank of transformer and the average winding-to-average oil gradient). Oil viscosity changes and loss variation with temperature are taken into account. The new thermal models will be validated using experimental (fiber optic test) results obtained at varying load current on a 250 MVA-ONAF-cooled unit, a 400 MVA-ONAF-cooled unit and a 605 MVA-OFAF-cooled unit. The results are also compared with the IEEE-loading guide (1995) Annex G method.
88 citations
TL;DR: In this paper, a comprehensive test program was performed on a 2500-kVA oil natural-air natural cooling mode (ONAN) transformer without external cooling, and the results were verified by thermocouple measurements and tests at varying loading current.
Abstract: A comprehensive test program was performed on a 2500-kVA oil natural-air natural cooling mode (ONAN) transformer without external cooling. It is shown that the hot-spot to top-oil temperature gradient depends on the transformer construction. The top-oil time constant formula, which has already been defined and validated in the authors' previous work related to transformers with external cooling, is modified in order to take into account the basic design differences. The results are verified by thermocouple measurements and tests at varying loading current. The hot-spot and top-oil temperature responses predicted by the IEEE Loading Guide, Annex G, are also compared to the measured values.
80 citations
TL;DR: In this paper, a 40 MVA, oil-forced air-forced (OFAF) transformer unit in service has been upgraded and the permanent online monitoring system has been improved.
Abstract: In order to properly assess operating conditions of a 40 MVA, oil-forced air-forced (OFAF) transformer unit in service the permanent online monitoring system has been upgraded Dissolved gas analysis laboratory measurements are also applied The hot-spot temperature and the top-oil temperature responses predicted by two different thermal methods are compared to measured values
40 citations
Journal Article•
8 citations
Cited by
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TL;DR: In this article, the authors introduce hot-spot and top-oil temperature thermal models for more accurate temperature calculations during transient states based on data received in a normal heat run test (i.e., the top oil in the tank of the transformer and the average winding-to-average oil gradient).
Abstract: The aim of this paper is to introduce hot-spot and top-oil temperature thermal models for more accurate temperature calculations during transient states based on data received in a normal heat run test (i.e., the top oil in the tank of the transformer and the average winding-to-average oil gradient). Oil viscosity changes and loss variation with temperature are taken into account. The new thermal models will be validated using experimental (fiber-optic test) results obtained at varying load current on a 250-MVA-ONAF-cooled unit, a 400-MVA-ONAF-cooled unit and a 605-MVA-OFAF-cooled unit. The results are also compared with the IEEE-Loading guide (1995) Annex G method.
285 citations
TL;DR: A study is presented to assess the impact of PEV charging on a local residential distribution transformer in the US.
Abstract: Due to the characteristics of electric power generation, transmission and distribution in the U.S., experts have identified local distribution as a likely part of the chain to be adversely affected by unregulated PEV (Plug-in Electric Vehicle) charging. This paper presents a study performed to assess the impact of PEV charging on a local residential distribution transformer.
201 citations
TL;DR: The fault diagnosis results of IEC TC 10 database show that the proposed ODGR with SVM may be used as an alternative tool for transformer fault diagnosis and the robustness and generalization ability of ODGR is confirmed.
Abstract: Dissolved gas analysis (DGA) of oil is used to detect the incipient fault of power transformers. This paper presents a new approach for transformer fault diagnosis based on selected gas ratios concentrated in oil and support vector machine (SVM). Firstly, based on IEC TC 10 database, the optimal dissolved gas ratios (ODGR) are obtained by genetic algorithm (GA) that is designed for simultaneous DGA ratios selection and SVM parameters optimization. Three traditional methods, namely, DGA data with SVM and back propagation neural network (BPNN), IEC criteria, and IEC three-key gas ratios with SVM and BPNN are employed for effectiveness comparison. The fault diagnosis results of IEC TC 10 database show that the proposed ODGR with SVM may be used as an alternative tool for transformer fault diagnosis. In addition, the robustness and generalization ability of ODGR is confirmed by the diagnosis accuracy of 87.18% of China DGA samples. The obtained results illustrate that it is preferable to apply the proposed ODGR to transformer fault diagnosis with the assistance of SVM.
170 citations
TL;DR: In this article, the authors conduct a literature survey and reveal general backgrounds of research and developments in the field of transformer design and optimization for the past 35 years, based on more than 420 published articles, 50 transformer books, and 65 standards.
Abstract: With the fast-paced changing technologies in the power industry, new references addressing new technologies are coming to the market. Based on this fact, there is an urgent need to keep track of international experiences and activities taking place in the field of modern transformer design. The complexity of transformer design demands reliable and rigorous solution methods. A survey of current research reveals the continued interest in application of advanced techniques for transformer design optimization. This paper conducts a literature survey and reveals general backgrounds of research and developments in the field of transformer design and optimization for the past 35 years, based on more than 420 published articles, 50 transformer books, and 65 standards.
159 citations
TL;DR: In this article , the authors used horseshoe shape of fin with perforated tape at the bottom of pipe to improve the thermal efficiency of hybrid nano-powders.
148 citations