5-level cascaded inverter based D-STATCOM with LPF-BPF fundamental active current extractor

This paper proposes a simple 3-step fundamental active current extraction scheme for a 1-phase 5-level cascaded H-bridge inverter (FL-CHBI) based distributed static compensator (D-STATCOM). Firstly, the proposed algorithm employs band pass filter (BPF) and low pass filter (LPF) for the determination of the peak magnitude of fundamental component of load current, Im1. Secondly, BPF and LPF are utilized to process the supply voltage for unit vector template generation (UVT), thereby ensuring effective operation even under nonsinusoidal supply voltage. Lastly, based on Im1 and UVT, the proposed LPF-BPF fundamental current extractor provides instantaneous value of fundamental active component of load current which when drawn from the supply ensures that the source current is sinusoidal and unity power factor (UPF) is maintained at the supply end. The extracted current is further processed to take into account the regulation and balancing of the dc-link voltages. The operation of the 1-phase FL-CHBI based D-STATCOM with the LPF-BPF fundamental current extractor scheme is analyzed for steady state and dynamic operation under non-distorted and distorted supply voltages. The performance analysis reveals IEEE standard-519 compliant operation of the D-STATCOM with proposed extraction scheme.