Analysis of the impact of non-sinusoidal voltage levels in the power grid of apartment buildings on the reliability and efficiency of transformers

The effects of mass implementation of energy-saving lighting on the permissible level of loading of the supply transformer were analyzed. The influence of non-sinusoidal voltages and currents on transformer wear was analyzed. Distortions of sinusoidal shape of voltages and currents lead to additional power losses in transformer. They cause heating of the insulation and windings of the transformer, increased losses and accelerated wear and tear. Higher harmonic components of voltage and current in a 0.4 kV network are caused by the presence of various energy-saving lighting lamps with non-linear volt-ampere characteristic, which include compact fluorescent and LED light sources. As a result, the transformer designed to operate at a frequency of 50 Hz experiences an additional adverse effect in the form of power losses and accelerated wear of electrical insulation, which leads not only to the deterioration of its technical and economic performance characteristics, but also to a significant decrease in reliability associated with the influence of higher harmonic components of voltage and current on equipment failure. It is shown that the lack of power factor correction schemes for low-power compact fluorescent and LED lamps causes the growth of nonsinusoidal voltage and current as they spread, which in turn causes the need to adjust the limit load of transformers to ensure their rated thermal mode. One way to maintain operational reliability under such conditions is to limit the transformer load depending on the level of higher harmonics in the network, as well as to predict the residual life of the operating transformer. Measuring the values of current transformer load and current levels of higher harmonic components of voltage and current will allow not only to calculate an acceptable load factor of the transformer (for the condition of insulation wear), but also to estimate the current residual life of transformer equipment using a neural network model.

1. GOST 14209-85 (IEC 354-91) Interstate Standard. Guidelines for loading of power oil transformers.

2. Bondarenko N. E., Latyshov K. V., Strizhichenko A. V. Influence of higher harmonic components of voltage on power losses in transformer. // Energy and resource saving: industry and transport 2019; (2): 10 – 13.

3. Assessment of the influence of higher harmonic components of current on the rate of relative wear of winding insulation of power transformer / N. E. Bondarenko, K. V. Latyshov, E. G. Zenina, A. V. Strizhichenko. International scientific and practical conference, Volzhsky, October 23 – 26, 2019: abstracts. – Volzhskiy: Branch of Federal State Budgetary Educational Institution of Higher Professional Education "National Research University "MPEI" in Volzhskiy 2020;: 40 – 42.

4. Assessment of reliability of electrical equipment in the presence of higher harmonics currents and voltages / M. M. Sultanov, E. G. Zenina, V. G. Kulkov, O. I. Zhelaskova / Electrotekhnika 2021(8): 62 – 68.

5. GOST 32144-2013 Electrical Energy. Compatibility of technical means electromagnetic. Quality standards of electric energy in general purpose power supply systems.

6. Influence of power quality parameters on reliability of power transformer equipment of power plants and distribution networks / The third conference "Problems of thermal physics and power engineering" / A. V. Strizhichenko, E. G. Zenina, M. M. Sultanov, O. I. Zhelyaskova / Journal of physics: conference series 2020; 1683: 1 – 5.

7. C57.110:2008 "IEEE recommended practice for establishing liquid-filled and dry-type power and distribution transformer capability when supplying non sinusoidal load currents – red line", 2008.

8. Investigation on dielectric breakdown behavior of thermally aged cross-linked polyethylene cable insulation / Ch. Kim, P. Jiang, F. Liu, S. Hyon, M. Ri, Y. Yu, M. Ho // Polymer Testing 2019;: 80.

9. Development of a centralized system for data storage and processing on operation modes and reliability indicators of power equipment / M. M. Sultanov, Y. A. Gorban, A. A. Smirnov, V. A. Yurov / Proceedings of the 3rd 2021 International Youth Conference on Radio Electronics, Electrical and Power Engineering, REEPE 2021, 2021, 9388022.

10. Development of complex system of estimation of technical state of generating equipment with use of neural network simulation // P. V. Shamigulov, M. M. Sultanov, Sh. M. Militonyan,Yu. Gorban 2022. №6: 136 – 145. DOI: 10.24160/1993-6982-2022-6-136-145.