Algorithm for computing switching time in VAPF

A new voltage type of active power filter (VAPF) and its control algorithm are proposed to eliminate harmonic voltage contaminations in power systems. The amplitude of the compensation voltage produced by the VAPF is controlled by the working status of a switch network. From the proposed compensation algorithm, the switching on-off time can be instantaneously calculated. Therefore, the compensation is more accurate and more rapid than before. The control method is advantageous to the realization of a fully-digital control and to the use of the intelligence control. The validity of the filter and the algorithm has been verified by results of simulation testings.