Effects of control systems time delay on the performance of direct harmonics elimination [power network active filters]

Active filters are power electronic systems that absorb the harmonic currents in a network, produced by nonlinear loads or apparatus such as high-voltage-direct-current (HVDC) converters. Active filters can be classified into two categories, based on their underlying control methods. The performance of the active filter can be adversely affected by control and measurement delays in the controls. This paper investigates the effects of control circuit time delay on the performance of direct harmonic elimination. Using analytical and transient simulation, this paper investigates the impact of this delay when the filter is based on the ´direct´ method.