Coordinated active power control between shunt and series converters of UPQC for distributed generation applications

Abstract

This paper presents a new concept of co-ordinated active power sharing between shunt and series converters of unified power quality conditioner (UPQC) for distributed generation applications. Normally, the UPQCs are used to mitigate both voltage and current power quality problems. However, these UPQCs are also used for delivering active power in addition to its power quality improvement by integrating distributed generation (DG) at the DC link of back to back connected converters. But, only the shunt converters are used to carry the whole active power from the DG sources and the series converters are used to handle only voltage related power quality problems. So, the shunt converter is loaded heavily and the series converter is kept idle in steady state cases. The more dependency on the shunt converter also reduces the reliability of the total system. This proposed control strategy is used to carry active power through both series converter and shunt converter even at the steady state conditions. The proposed method improves the utilization of the converters and also the reliability of the system. The effectiveness of the proposed control strategy is demonstrated by comparing with the conventional control algorithm, where only the shunt converter is used to carry active power. The proposed system is validated by performing hardware in loop (HIL) tests using OPAL-RT and dSPACE DS1103.