Composite observer-based control algorithm for distribution static compensator in four-wire supply system

This study presents an implementation of composite observer-based control algorithm in three-leg voltage source inverter (VSI)-based distribution static compensator (DSTATCOM) in four-wire power distribution network. This control algorithm is used for extraction of load fundamental current components of polluted load currents. These components of load currents are used for estimation of reference source currents to generate the gating pulses of insulated gate bipolar transistors used in VSI of DSTATCOM. This control algorithm is implemented for mitigation of power quality problems such as reactive power compensation, harmonic elimination and load balancing under linear/non-linear loads. The performance of DSTATCOM is found quite satisfactory for these unbalanced loads.