Leszek S. Czarnecki

Power variation of a customer load can disturb other loads in distribution systems and compensators for such loads are sometimes needed. Voltages and currents in systems with such loads can be asymmetrical, nonperiodic, distorted and even unpredictable. Consequently, reference signals for the compensator control have to be generated in a situation where the power properties of the load are not well specified.

Voltages and currents in systems with time-varying loads, although nonperiodic, can be treated as quantities with a disturbed periodicity. These are referred to as semi-periodic quantities. Under such an assumption, the Current Physical Components (CPC) power theory can by used for estimation of the power properties of such loads. In such a case, the CPC power theory provides fundamentals for a quasi-instantaneous generation of reference signals for the compensator control, based both on the frequency- and on the time-domain approach. The paper presents fundamentals of generation of reference signals for unbalanced loads with semi-periodic voltages and currents.