Interaction and Coordination Between Reactive Compensation and Harmonic Suppression for Three-Phase Buck-Type Dynamic Capacitor

Dynamic capacitor (D-CAP) could be designed to compensate reactive power and suppress harmonic currents simultaneously by means of regulating DC and harmonic terms in duty-ratio modulation signal. However, the main constraint is that the amplitudes of DC and harmonic terms are always correlative, leading to the interaction between reactive and harmonic currents of D-CAP. To minimise mutual effects between reactive and harmonic currents, this study presents coordinated control between reactive compensation and harmonic suppression for buck-type D-CAP. The major concern of coordinated algorithm is to pre-estimate and select the DC and harmonic terms reasonably according to their inter-constraint relationship. Thus, D-CAP can optimise the generation of reactive and harmonic current references in different scenarios. Meanwhile, selective current control in multiple synchronous reference frames is employed to regulate reactive and harmonic current effectively. A series of experimental results are provided to verify the correctness of proposed coordinated control.