Flicker Suppressor by Thyristor

One of the difficulties which are encountered by direct connection of the accelerator to the utilities is the effect of pulsed reactive power on the utilities with respect to the customer´s interference and the system stability. To suppress the voltage flickers caused by the pulsed reactive power, several types of machines have been investigated, namely capacitor banks with thyristor switches, series capacitors, saturable reactor and reactor with thyristors. Among these, the reactor with thyristors was employed in KEK accelerator with respect to performance, maintenance, technical feasibility and economical point. The actual operation of reactive power control by ignition angle of thyristor was satisfactory. The swing of 14 MVAr reactive power was stabilized within ??5% and the voltage flicker was suppressed from 3% to 0.5% which is enough less than the permissible value suggested by the electrical company. The harmonic current which is associated with thyristor was absorbed to ac filters that was also served as the reactive power compensator.