Need of technical accounting at electric energy quality reduction under conditions of AC traction substation

Abstract

Purpose. Justification of the need for electrical energy quality technical accounting based on the results of monitoring a 10 kV traction substation transformer mode. Methodology. Measurements of the current and voltage at secondary busbars of a 10 kV traction substation and monitoring of the electrical energy parameters in the observation interval were carried out. Using the Fourier analysis methods, a current and voltage harmonics level was analyzed. For the current and voltage fundamental harmonic, the positive, negative and zero sequences components are analyzed using the Fortescue transformation. Based on the secondary voltage side current discrete spectrum, the calculation of power loss growth in cable line and transformer windings was carried out. Findings. As a result of measuring the electrical mode parameters on the transformer secondary voltage busbars, a significant distortion of current and voltage, as well as significant fluctuations in active and reactive power, were established. During the observation interval, significant changes in the power factor are noted. Based on the calculation of additional losses from current higher harmonics in the cable line, it has been established that the current load of the line can be reduced by 10% while eliminating the current higher harmonics. A similar calculation of loss growth carried out for the traction transformer showed that in the analyzed case its load should not exceed 87.8% of the nominal one. Originality. A significant level of harmonic current distortion on secondary voltage busbars of the traction transformer leads to its underutilization, whereas the voltage distortion level, as an electrical energy quality indicator in accordance with current standards, remains within the permissible range. This requires a revision of electrical energy quality indicators, from the standpoint of power, which is due to both current and voltage. Practical value. The indicators obtained as a result of calculations can be used to correct the load of traction substation transformers. The introduction of the obtained indicators into the set of parameters for electrical energy technical metering is a prerequisite for the development of measures to improve the electrical energy quality.