Harmonic and imbalance voltage mitigation in smart grids: A DSTATCOM based solution

This paper presents a control system for a DSTATCOM with which to compensate the voltage sags, unbalanced voltages and voltage harmonics caused by unbalanced loads and nonlinear loads, which can be use to enhance the power quality in smart grids. The compensation of the voltage sags is carried out by injecting reactive power, while the voltage harmonics and voltage imbalances are ameliorated by canceling out the harmonics and the imbalances of the grid current. The control scheme is designed in the synchronous reference frame with a nested control structure which contains PI controllers and resonant regulators. These regulators are tuned at the harmonic frequencies to be eliminated and can be implemented to incorporate an update of those frequencies. Simulation results show the resultant time response of the voltage at the point of common coupling and the grid current.