dPLL-based control of a hybrid wind-solar grid connected inverter in the distribution system

A novel differentiation phase locked loop (dPLL)-based control technique is used for control of a three-phase hybrid wind-solar grid connected inverter (HWS-GCI) with a capacitor-supported DC link. The DC link is simultaneously interfaced to a solar photovoltaic and permanent magnet brushless DC wind generator via unidirectional DC-DC converters, in a two-stage topology, to channelise excess power generation to the grid, thus increasing the energy conversion capability. In addition, the HWS-GCI is used as a distribution static compensator to enhance the dynamic performance of the system, by the use of a novel harmonics isolation control algorithm based on differentiation and variable coefficient proportional-integral-derivative controller. The algorithm possesses fast dynamic response and preserves the mutual relationship of the three-phase currents, allowing the accurate detection of load side or source side phase unbalancing. A comparison of the proposed technique with previously known methods is provided to establish the competency of the algorithm. The experimental performance validation under non-linear load unbalancing and sudden changes in solar insolation and power generated by a wind generator are considered using the real-time implementation platform.