Combined time‐domain and frequency‐domain approach to hybrid compensation in unbalanced non‐sinusoidal systems

This paper deals with improving power quality in a situation where this quality is degraded by a low‐quality load that may cause voltage asymmetry, harmonic distortion and variation of the voltage RMS value. The paper discusses a decomposition of the useless component of the supply current into a component compensated with an adaptive passive circuit, of parameters updated to varying load conditions once a cycle, and a component compensated with a continuously controlled current source. Controlling such a hybrid compensator requires that some parameters of the load, defined in the frequency domain, are measured along with instantaneous values of voltages and currents. Compensators with such a structure and control make it possible to circumvent limitations of active power filters with respect to their power rating. Copyright © 1994 John Wiley & Sons, Ltd