Design and Analysis of Three-Phase UPQC under Steady-State and Dynamic-State Conditions

Abstract: This paper investigates the design and performance of a three-phase UPQC in steady state and dynamic state conditions. The UPQC consists of the DC link used to connect the voltage compensators in back-to-back arrangement, which is shared by both series and shunt connections. The UPQC’s shunt compensator adjusts for load current harmonics. The series compensator addresses problems regarding grid-side power quality, such as grid voltage sags and swells, by injecting a suitable voltage in phase with the grid voltage during voltage sag and out of phase during voltage swell conditions. An improved SRFT (Synchronous Reference Frame Theory) controller has been used with the series and shunt compensator. To maintain the DC-link voltage, the shunt compensator uses a PI controller. The steady state and dynamic performance of the developed model are examined by utilizing Matlab-Simulink and a nonlinear load.