Symmetrization of asymmetrical three-phase load supplied from asymmetrical non-ideal voltage source with periodic nonsinusoidal waveforms

Abstract

The problems presented in the paper deal with a three-phase four-wire system. The considered system is composed of: the three-phase asymmetrical voltage source with periodical nonsinusoidal waveforms, inner impedances of the voltage source and asymmetrical linear three-phase loads. In contrast to earlier approaches the voltage source is not symmetrical. In the paper a method of symmetrization of these systems has been proposed. After symmetrization it is possible to obtain symmetrical line currents of the system. Their RMS values and active power losses on source impedances can be lower. Moreover, the source can generate greater active power than before symmetrization. The working point after symmetrization can be obtained by means of connection of a symmetrizing system. The main goal is to use the symmetrizing system composed of LC one-ports, but generally it is necessary to use the active symmetrizing system. Their structure is determined as a result of a synthesis process. In this paper the symmetrization problem has been solved by using the symmetrical components theory and compensation of reactive power for each harmonic of the voltage under consideration.