Adaptive notch filter based multipurpose control scheme for grid-interfaced three-phase four-wire DG inverter

The power electronic converter and its control system form an integral part of distributed generation (DG) systems interfacing renewable energy sources to the utility network. This paper proposes an adaptive notch filter-based multipurpose control scheme for grid interfacing DG inverter under corrupted grid conditions. The proposed control scheme uses a frequency adaptive sequence components extractor which is capable of extracting instantaneous symmetrical components and harmonic components of three-phase signals. The DG inverter in this study consists of three single-phase voltage source inverters with common dc bus and coupled to utility grid via three single-phase transformers. The DG sources are represented as constant dc voltage source on its dc side. The proposed control scheme enables the DG inverter to perform multiple tasks such as: reference power injection to grid, load reactive power support and compensation of harmonic, unbalanced and neutral currents. The effectiveness of the proposed control scheme is evaluated through MATLAB/Simulink simulations and experimentally verified using a hardware-in-the-loop (HIL)-based system.