Dynamic performance of grid-connected wind farms with and without UPFC: A case study on ashagoda wind farm

Abstract

Voltage variations are a major concern in grid-connected wind turbines systems. In Ashagoda wind farm, different voltage quality problems such as voltage sag, voltage dip, and voltage fluctuations have been observed for causes like loss of system voltage, short circuit faults, and tripping of wind turbines that resulting in a huge power loss. Under three-phase short circuit fault, the voltage at the point of common coupling (PCC) instantly drops below 80% of its nominal value which results in instability in the rotor speed. In this paper, a unified power flow controller (UPFC) is interconnected at the PCC to enhance the dynamic response of ac grids and also improves the transmission capability of the system. The system is modeled and simulated in Dig Silent Power Factory. The results of simulation clearly illustrate that UPFC can improve voltage regulation at the point of common coupling and maintain a reliable connection between the wind turbine and the grid under minor levels of voltage fluctuation on the grid side.