The impact of controller time delay on the performance of shunt hybrid power filters

This paper presents an investigation on influence of the control system time delay on the performance of the shunt hybrid power filter, consisting of a shunt passive filter connected in series with an active power filter. Frequency response of the shunt hybrid power filter is investigated by mathematical analysis and it is shown that existence of controller time delay degrades the harmonic compensation performance of hybrid power filter at frequencies above the tuned frequencies of the passive filter. Moreover, in the cases with notable time delay, the harmonic magnification phenomenon may be occurred. Computer simulations for a typical distribution system including a thyristor controlled rectifier and a shunt hybrid power filter have been carried out to validate the presented analysis. Harmonic contents of the source current have been calculated for different cases to demonstrate the influence of controller time delay on the harmonic compensation characteristics of the shunt hybrid power filter in different frequencies.