Dynamic mitigation of grid current harmonics using the power sphere concept in voltage source inverters

Voltage source inverters (VSI) connected to intermittent renewable sources may have periods of low active power production. When the power generated at the source is below the power rating of the inverter, the remaining unused rating of the inverter can be used to compensate the harmonic distortion in the grid. This paper presents the realization of a VSI with Active Power Filter capabilities, which is able to control the compensation of individual load harmonics up to the 17
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as a function of the variation of the unused rating of a VSI. In order to select the number and magnitude of harmonic to mitigate, the paper analyses the utilization rating of the VSI in light of the power theory used in the latest IEEE standards. This analysis results in the derivation of a novel “power sphere” concept that is helpful to establish the magnitude of harmonic compensation needed to fully utilize the unused rating of a VSI at a given time. The performance of the selective compensation of individual harmonics in a VSI is validated in simulations and in a 3-phase 1kW DSC-controlled experimental platform.