CALCULATION OF THE TEMPERATURES AND LIFETIMES FOR DISTRIBUTION TRANSFORMERS
Mots-clés :
Power transformers, Oil-paper insulation, Oil and hot spot temperatures, Consumed and remaining lifetimesRésumé
The paper presents the methods of exponential functions and differential equations recommended by IEC and IEEE for the calculation of the oil θo and hot spot θh temperatures in power transformers, in the absence and presence of solar radiation. Considering the case of distribution transformers, for which the load factor K shows variations in small time intervals, the authors propose a new (analytical) method for calculating temperatures (θo and θh), both in the absence and in the presence of solar radiation. To highlight the importance of the calculation method and solar radiation, the quantities θo and θh are calculated (in two days from 2019) by three methods, as well as the consumed and remaining lifetimes for two transformers, with the same load and located in areas with different values of temperature and solar radiation. Finally, the influence of solar radiation, place of operation of the transformer, and calculation method on the values of temperatures and lifetimes are analyzed.
Références
(1) M. I. Bey, P. V. Noţingher, C. Stancu, The influence of solar radiation on the lifetimes of power transformers, Electrotehnica, Electronica, Automatica (EEA), 68, 1, pp. 45-58 (2020).
(2) A.N. Jahromi, R. Piercy, S. Cress, R.R.J. Servicee, W. Fan, An approach to power transformer asset management using health index, IEEE Electrical Insulation Magazine, 25, 2, pp. 20-34 (2009).
(3) M. Wang, A.J. Vandermaar, K.D. Srivastava, Review of condition assessment of power transformers in service, IEEE Electrical Insulation Magazine, 18, 6, pp. 12-25 (2002).
(4) P.V. Notingher, L.M. Dumitran, S. Busoi, G. Tanasescu, The use of electrical resistivity to estimate the lifetime of power transformers oils, Electrotehnica, Electronica, Automatica (EEA), 66, 1, pp. 100-108 (2018).
(5) P.V. Notingher, Cristina Stancu, L.M. Dumitran, P. Notingher jr., Aleksandra Rakowska, K. Siodla, Influence of the Ageing State of Insulation Systems on Absorption/Resorption Currents, Revue Roum. Sci. Tech. – Electr. Et Energ., 53, 2, pp. 163-178 (2008).
(6) Al.V. Vasovic, J. Lukic, D. Mihajlovic, B. Pejovic, Z. Radakovic, U. Radoman, A. Orlovic, Aging of transformer insulation – experimental transformers and laboratory models with different moisture contents: Part I – DP and furans aging profiles, IEEE Trans. on Dielectrics and Electrical Insulation, 26, 6, pp. 1840-1846 (2019).
(7) C. Oria, A. Ortiz, D. Ferreño, I. Carrascal, I. Fernández, State-of-the-art review on the performance of cellulosic dielectric materials in power transformers: mechanical response and aging, IEEE Trans. on Dielectrics and Electrical Insulation, 26, 3, pp.939-954 (2019).
(8) P.V. Notingher, L.M. Dumitran, S.A. Busoi, Lifetime estimation of composite insulations by absorption/resorption currents method, Revue Roum. Sci. Tech. – Electr. Et Energ., 55, 4, pp. 365–374 (2010).
(9) S.P. Kennedy, T. Gardner, J.N. Bribe, R. Ringlet, J. Cubin, Hot spot studies for sheet wound transformer windings, 80th International Conf. of Double Clients, pp.1-11, 2013.
(10) J.N. Bribe, J. Cubin, W. Macdiarmid, Transformer winding hot spot temperature determination, pp. 1-10 (2012), https://www.scribd.com/document/ 89232477/ Transformer-Winding-Hot-Spot-Temperature-Determination.
(11) P.V. Notingher C. Stancu, G. Tanasescu, S. Busoi, Determination of lifetime line parameters for power transformer insulation, Electrotehnica, Electronica, Automatica (EEA), 66, 4, pp. 59-65 (2018).
(12) ***IEC 60076-7, Power Transformer-Part 7: Loading Guide for Oil-Immersed Power Transformers, pp. 1-113 (2005).
(13) ***ANSI/IEEE, IEEE Std. C57.91-2011, IEEE guide for loading mineral-oil-immersed transformers and step voltage regulators, pp. 1–172 (2011).
(14) A. Vidja, H. Nayakpara, R. Bhalera, K. Bhargava, Methods for calculating the transformer hot-spot temperature and lifetime prediction, 2018 3rd International Conf. for Convergence in Technology (I2CT), Pune, India, pp. 1-4 (2018).
(15) P.V. Notingher, G. Tanasescu, Determination of estimated, consumed, and remaining lifetimes of paper - oil transformers insulation based on winding insulation resistance, Proc. of 2018 IEEE International Conference on High Voltage Engineering and Application (ICHVE), Atena, 10-13 (2018).
(16) B. Gorgan, P.V. Notingher, J.M. Wetzer, H.F.A. Verhaart, P.A.A.F. Wouters, A. van Schijndel, Influence of solar irradiation on power transformer thermal balance, IEEE Trans. on Dielectrics and Electrical Insulation, 19, 6, pp. 1843-1850 (2012).
(17) H. Nordman, N. Rafsback, D. Susa, Temperature responses to step changes in the load current of power transformers, IEEE Trans. on Power Delivery, 18, 4, pp. 1110-1117 (2003).
(18) G.W. Swift, T.S. Molinski, W. Lehn, A Fundamental Approach to Transformer Thermal Modelling, IEEE Trans. on Power Delivery, 16, 2, pp. 171 – 177 (2011).
(19) ***Painting of Transformers and Circuit Breakers, Facilities Instructions, Standards, and Techniques, 3-7, pp. 1-4 (1991).
(20) V. Badescu, Modeling Solar Radiation at the Earth's Surface. Recent Advances, Springer-Verlag Berlin Heidelberg, 2014.
(21) B. Gorgan, Estimation of degradation conditions and remaining life of power transformers, Ph.D. Thesis, University Politehnica of Bucharest, Bucharest, 2012.
(22) D.Y. Goswami, F. Kreith, J.F. Kreider, Principles of Solar Engineering, Second Edition, Taylor and Francis, 2000, pp. 26-34.
(23) S.V. Szokolay, Solar declination and the equation of time, International Journal of Solar Energy, 5, 3, pp. 143-146 (1984).
(24) K. Diwyacitta, R.A. Prasojo, A. Suwarno, H. Gumilang, Effects of a lifetime and loading factor on dissolved gases in power transformers, International Conf. on Electrical Engineering and Computer Science (ICECOS), Palembang, Indonesia, pp. 243-247, 2017.
(25) M. Mahoor, A. Majzoobi, Z.S. Hosseini, A. Khodaei, Leveraging sensory data in estimating transformer lifetime, North American Power Symposium (NAPS), Morgantown, WV, USA, pp. 1-6, 2017.
(26) N.A. Munir, Y. Mustafa, F. Siagian, Analysis of The Effect of Ambient Temperature and Loading on Power Transformers, 2nd International Conf. on High Voltage Engineering and Power Systems (ICHVEPS), Bali, Indonesia, pp. 1-6, 2019.
(27) G. Tanasescu, B. Gorgan, S. Busoi, A. Badita, P. V. Notingher, Monitoring and diagnosis of electrical equipment using web software. Health index and remaining lifetime estimation, Proceedings of the International Conf. on Diagnostics in Electrical Engineering (Diagnostika ́16), Pilsen, pp. 1-4, 2016.
(28) J. Foros, M. Istad, Risk and remaining lifetime estimation of power transformers, IEEE Trans. on Power Delivery (2020).
