Method for Determining the Complex Value of the Total Power Losses in the Power Supply System

Abstract

The article proposes a method for calculating the total losses in the equipment of the power supply system used to transport electrical energy. The developed method takes into account the totality of the elements of the power supply system and the loads associated with the general operating mode, in contrast to the known methods, in which losses are calculated separately according to the components and to the type of equipment. The method is based on the equivalent circuit of the power supply system, in which a reduced symmetrical T-shaped equivalent circuit of one phase is used for a power three-phase two-winding transformer. It has been analytically proved that consideration of issues related to the losses calculation in the power supply system separately in the power line and in the power two-winding transformer without taking into account their mutual influence on each other leads to inaccurate calcula-tions. An estimation of the error in the losses calculations and the full power consumption using the proposed method was made in comparison with the mathematical model. The mathematical model was developed in the Multisim soft-ware package. As an example for performing calculations, a power supply system was adopted, consisting of a source with a rated voltage of 10 kV + 10 %, a power line made using a three-core cable and a power three-phase two-winding transformer of the TMG11 brand with a rated power and load of 250 kVA. The calculated values when using the developed method practically coincide with the data obtained from the results of the mathematical model. The cal-culation of the total losses of active power, in the power supply system adopted for the mathematical model is carried out when calculating separately the load losses in the power line and conditionally constant and load losses in the power transformer. The relative error of the calculating results of the active power total losses in this case was 12.6 %. It is proved that using the developed method will improve the accuracy of calculating the total losses and make it pos-sible to carry out further studies aimed at assessing the influence of the power transmission line parameters as well as the load and the magnitude of the network supply voltage on the total losses in the equipment of the power supply sys-tem used to transport electric energy.