A novel detecting noise reduction scheme for voltage-regulated current-fed power filter

Active power filters have been developed to solve the harmonics disturbance problems on power system networks. Particularly for current-type active power filters, a voltage regulation scheme is considered to control the voltage of capacitor at the input side of a nonlinear load. For precise control, the value of voltage drop at the AC side must be included. Because of the reactance of the filter, external noises are added to the detected voltage drop signal and hence the resultant signals will be seriously distorted, particularly where an electronic differentiator is used. To reduce these noises, a novel detected noise reduction scheme with an observer based algorithm is proposed. The designed observer algorithm is applied and then investigated by digital simulation. Also the experimental results are shown to verify the validity of proposed scheme.