Control of D-STATCOM under unbalanced and distorted voltages using Synchronous Detection method for load compensation

This paper presents Distribution Static Compensator (DSTATCOM) configuration in three phase four wire system, using three level Neutral Point Clamped (NPC) inverter operated in current control mode for load compensation to enhance the quality of power. The behavior of shunt compensator is analyzed using Synchronous Detection method. The purpose of this compensating scheme is to provide completely balanced and sinusoidal source currents under unbalanced and distorted source conditions. The chosen control algorithm includes three different approaches-equal current, equal power and modified equal current. The above said criteria are compared graphically and analytically for unbalanced and non-linear load condition. Results obtained show that modified equal current approach is more effective than the other two even if the source voltages are severely distorted and unbalanced. For realization, an extensive digital simulation is done using MATLAB environment.