Voltage compensation using PSO-PI controlled STATCOM in a DFIG-based grid-connected wind energy system

Abstract

Wind energy conversion systems connected to the grid usually employ doubly-fed induction generator (DFIG) owing to its inherent advantages like fault ride-through capability. Severe voltage dips and consequently voltage instability may occur due to faults and other disturbances in weak power systems connected to a DFIG-based wind farms. FACTS devices like static synchronous compensator (STATCOM) may be harnessed to provide the required voltage support dynamically at the point of common coupling (PCC). In the proposed methodology, the STATCOM, which is included in the power system connected to a DFIG-based grid-connected wind farm, is controlled using particle swarm optimization (PSO). The PSO-PI controlled STATCOM provides voltage compensation at the PCC in five test cases - simultaneous occurrence of step change (drop) in wind speed and dip in the grid voltage, single line to ground fault, line to line fault, double line to ground fault at a system bus and sudden increase in load by more than thousand times at the PCC. All the simulations have been done in MATLAB / SIMULINK and the results obtained clearly indicate the improvement in the voltage profile at the PCC due to the reactive power support provided by the PSO-PI controlled STATCOM.