A control algorithm for flexible operation of DSTATCOM for power quality improvement in voltage and current control mode

Distribution Static Compensator (DSTATCOM) is used for power factor correction, voltage regulation, load balancing, and harmonic elimination. A DSTATCOM can not fulfill all these objectives simultaneously. In the presented work, authors have proposed a control algorithm for dual functional DSTATCOM that enables it to operate either in current control mode (CCM) or in voltage control mode (VCM). A new control algorithm has been devised that allows DSTATCOM to smoothly switch over from CCM to VCM and vice versa. In VCM it regulates load terminal voltage at a desired magnitude, whereas in CCM it injects reactive and harmonics current such that supply sees unity power factor. PSCAD/EMTDC software is used for extensive simulation studies and results of DSTATCOM operation in VCM, CCM, and transition from one mode to another mode are presented in detail.