A Fast Acting 1/z Controller for Shunt Active Filter Operation for Harmonics and Reactive Power Compensation

This paper focused on the transient behavior of the shunt active power filter during harmonics and reactive power compensation. The transient response of the shunt active power filter (SAPF) is very important while compensating rapidly varying unbalanced and nonlinear loads. The dc-link capacitor voltage of SAPF is the function of load currents. Changes in load currents significantly affect the dc-link voltage of SAPF. The smooth operation of SAPF during change of loads needs variation of the dc-link voltage within prescribed limits. Conventionally, PI controller is used for this purpose which uses the deviation of the dc-link capacitor voltage from its reference value as input. However, the transient response of the conventional dc-link voltage controllers is slow. In this paper, a fast acting 1/z dc-link voltage controller based on the dc-link capacitor energy is proposed. The detailed modeling and simulation verifications are given to prove the capabilities of this fast acting 1/z dc-link voltage controller over conventional dc-link voltage controller. The results at different operating conditions such as application and removal of loads have been demonstrated to show the capabilities of this controller.