PQ Theory Based Power Quality Improvement in Distribution Level with D-STATCOM

Abstract

The Transient response of the distribution static compensator (DSTATCOM) is very important while compensating rapidly varying unbalanced and nonlinear loads. Any change in the load affects the dc link voltage directly. The sudden removal of load would result in an increase in the dc link voltage above the reference value where as a sudden increase in the load would reduce the dc link voltage below its reference value. The proper operation of DSTATCOM requires variation of the DC link voltage within the prescribed limits. Conventionally, a proportional-integral (PI) controller is used to maintain the dc-link voltage to the reference value. It uses the deviation of the capacitor voltage from its reference value as its input. However, the transient response of the conventional PI dc-link voltage controller is slow. In this paper, a fast acting dc-link voltage controller based on the energy of the dc-link capacitor is proposed and proposed shunt controller method by using PQ-Theory. Mathematical equations are given to compute the gains of the conventional controller based on the fast-acting dc-link controllers to achieve similar fast transient response. The detailed simulation studies are carried out to validate the proposed controller..