Current Harmonics From Single-Phase Grid-Connected Inverters—Examination and Suppression

Abstract

Environmental conditions and operational modes may significantly impact the distortion level of the injected current from single-phase grid-connected inverter systems, such as photovoltaic (PV) inverters, which may operate in cloudy days with a maximum power point tracking, in a non-unity power factor, or in the low voltage ride through mode with reactive current injection. In this paper, the mechanism of the harmonic current injection from grid-connected single-phase inverter systems is thus explored, and the analysis is conducted on single-phase PV systems. In particular, the analysis is focused on the impacts of the power factor and the feed-in grid current level on the quality of the feed-in grid current from single-phase inverters. As a consequence, an internal model principle based high performance current control solution is tailor-made and developed for single-phase grid-connected systems to produce high quality currents in different operation conditions, where a design procedure is also provided. The developed current controller in this paper can achieve a minimum steady-state error while maintaining a relatively fast transient response, and also being feasible in other single-phase applications as a promising harmonic mitigation solution. Experiments on single-phase gridconnected systems have verified the correctness of the relevant analysis and also the effectiveness of the tailor-made control solution in terms of good harmonic mitigation.

Experimental Evaluation of a CPT-Based Four-Leg Active Power Compensator for Distributed Generation

“…13(a) shows a distorted and unbalanced loadcurrent which has been obtained by modifying the crest factor, in each phase, of the Ametek programmable load. For this load the current has been separated into the currents defined by (5)(6)(7). This separation has been realised by the DSPACE platform in real time operation.…”

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Feedforward Harmonic Mitigation Strategy for Single-Phase Voltage Source Converter

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