Simulation of Negative Sequence Voltage Source Determination in Power Supply Systems

The article presents power quality issues in the power supply systems. It is shown that the quality of electrical energy in certain cases depends not only on the producers and suppliers of electricity, but also on the consumers. The occurrence of the deviations from the norm leads to the emergence of negative effects on electrical equipment of energy consumption organizations and electricity consumers thereby creating the conditions for the technological and electromagnetic damage occurrence, which are the reasons for the occurrence of losses and other negative consequences in case of violations of the electricity quality. The results of measurements of the voltage unbalance coefficients in negative sequences obtained by the authors of the article during electricity quality monitoring are presented. These results show that voltage unbalance in the negative sequence is present in the electrical networks with a voltage of 0.38 kV. It is shown on a computer model of a simple power supply system that the use of load currents and voltages can be used to identify the causes of asymmetry - different values of power (resistance) of a three-phase load or different values of the phase voltages of the supply network. The use of monitoring the resistance values in combination with the determination of the modulus and phase angle of the negative sequence voltage allows with the sufficient accuracy to determine the cause of the voltage unbalance.