Power Quality Improvement by UPQC device in Doubly Fed Induction Generator Wind Farm to Weak-Grid Connection

This paper mainly deals with the regulation of voltage at wind farm (WF) terminals and the improvement of power quality and WF stability in a WF to Weak-Grid connection. In facilities with moderated power generation, the WF are connected through medium voltage (MV) distribution headlines. A situation commonly found in such scheme is that the power generated is comparable to the transport capacity of the grid. This case is known as Wind Farm to Weak Grid Connection, and its main problem is the poor voltage regulation at the point of common coupling (PCC). Thus, the combination of weak grids, wind power fluctuation and system load changes produce disturbances in the PCC voltage, worsening the Power Quality and WF stability. This situation can be improved using Custom power devices technology (CUPS), the Unified Power Quality Compensator (UPQC). The internal control strategy is based on the management of active and reactive power in the series and shunt converters of the UPQC, and the exchange of power between converters through UPQC DC–Link. Simulations results show the effectiveness of the proposed compensation strategy for the enhancement of Power Quality and Wind Farm stability.