In this paper, a dc voltage controller along with a decoupled current control has been presented for the compensation of non-linear load using FACTS device STATCOM which also secures the unity power factor (UPF) at the point of common coupling. The STATCOM is employed with a three phase voltage source inverter (VSI) and dc capacitor. The design of the control model involves pole-zero cancellation and frequency domain analysis using root-locus method to obtain the parameters for the controller proposed. The quadrature axis current has been forced to be zero so that the source would be supplying only the real power to the load side. The transfer function for both of the loop has been formulized and the tuning of the controllers has been done with the help of modulus optimum and symmetrical optimum criteria to obtain the stable response.