250kVA Unified Power Quality Controller

This paper presents the development and field trial results of a unified power quality controller (UPQC). It is used to compensate power quality issues like voltage sags, swells, voltage unbalance, flicker, reactive currents and current harmonics. It is a combination of a shunt active filter as well as a series compensating stage connected before the load in series with the power network using a matching transformer. A 250 kVA UPQC is developed at Centre for the Development of Advanced Computing (C-DAC), Trivandrum, India and is under field trial at the centre. The principle of the proposed UPQC is discussed in detail. The performance of UPQC is evaluated by estimating the quality improvement in voltage and currents