Active Compensation of Unbalanced Currents and Current Harmonics Taken by a Non Linear Unbalanced Load Fed by a Distorted AC Mains

F. Labrique, A. Bricteux, and B. Janssens (Belgium)


Active filter, network harmonics, power factor, power electronic applications, unbalance compensation.


: The compensation by an active filter of the distorted currents of a dynamic non linear unbalanced load strongly depends on the capability of determining in real time the harmonic currents and the unbalance the filter must compensate. If the voltage of the AC source feeding the load shows itself non negligible harmonic distortion and/or unbalance (which may be the case inside the network of a plant) the identification of the compensation current the filter must deliver is not obvious. In this paper we describe a method to determine the currents which is based on the identification of the instantaneous positive-sequence component of the fundamental components of the AC voltage, keeping a power balance. Generation of compensation currents by a PWM controlled parallel active filter is then analysed. Simulations show the good performance expected from the method when compared with others and especially when AC mains voltages are significantly distorted.

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