Ngo Van Kyong, Kovernikova Lidiya Ivanovna. Prognozirovanie vliyaniya nesinusoidal'nogo rezhima seti na silovye transformatory [Prediction of the influence of the non-sinousoidal network mode on power transformers]. Sovremennye tekhnologii. Sistemnyi analiz. Modelirovanie [Modern Technologies. System Analysis. Modeling], 2019. Vol. 64, No. 4. Pp. 36–43. DOI: 10.26731/1813-9108.2019.4(64).36-43
At present, the electric network mode parameters often do not meet the requirements of GOST 32144-2013 in Russia and the guidelines No.39/2015/TT-BCT and No.25/2016/TT-BCT in Vietnam. In real operating conditions, there is very often a non-sinusoidal mode in electrical networks, the consequences of which are voltage and current harmonics. The harmonics cause overheating and damage to power transformers because they create additional active power losses, including no-load losses, load-resistive and eddy current losses in the windings, eddy current losses in other transformer elements. Additional losses cause the release of additional heat, which accelerates the aging process of winding insulation, magnetic circuits of power transformers and, as a result, the reduced service life of the power transformer. The problem of the negative influence of voltage and current harmonics on electrical equipment, on the efficiency of electric energy use, has recently been increasingly represented in Russian publications, at conferences, in government bodies. Consumers are increasingly applying to courts with claims against energy providers that supply them with electrical energy that does not meet the requirements of GOST 32144-2013. Therefore, there is a need to develop scientific methods that would show that low-quality electrical energy can lead, for example, to a reduction in the service life of electrical equipment. At present, automated systems for continuous monitoring of electrical energy quality indices and mode parameters in electrical networks are being developed. They can be supplemented by programs for calculating characteristics that predict the effect of voltage and current harmonics on various electrical equipment of both energy providers and electrical energy consumers. To predict the effect of voltage and current harmonics on power transformers, one can use a computer program developed and presented in this article. The program uses the characteristics offered in numerous publications, with the help of which the influence of voltage and current harmonics on power transformers is estimated and predicted. The program is developed using MS Excel and Matlab. As an example, the predictions of the effect of voltage and current harmonics on the power transformer installed at one of the railway traction substations were calculated with the help of the program. The parameters of the voltage and current harmonics used in the calculation were obtained as a result of measurements at the node connecting the traction transformer to the supply network. The results of the calculations show that the level of voltage and current harmonics that occurred at the time of the measurements can lead to a reduction in the service life of the power transformer by 6,98 years.
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