A series-shunt compensator with combined UPS operation

Series-shunt power quality compensators with the ability to function as an uninterruptible power supply (UPS) can solve a variety of power quality problems. This topology consists of two power electronic inverters. The shunt inverter is typically used as a voltage source during UPS operation, requiring a shunt inverter rated for the full load power. The rating of the series inverter is typically minimized to reduce cost, resulting in limited voltage compensation. This paper suggests a topology that enables the series inverter of a series-shunt compensator to assist the shunt inverter during UPS operation. The proposed topology allows the use of a shunt inverter with a power rating lower than the load rating, resulting in a compensator with reduced power rating while maintaining a high capacity for voltage compensation. This paper also suggests an arrangement of passive filters for switching ripple that does not adversely affect series voltage compensation. Practical results are presented, illustrating the operation of the proposed series-shunt UPS and series-shunt compensation for a capacitive nonlinear load.