COMPENSATOR FOR INSTANTANEOUS REACTIVE POWER

摘要

PURPOSE:To improve the compensating ability for the higher order harmonics contained in both reactive and active currents by applying the feedforward control which is not applied to a three-phase AC coordinate system to the higher harmonic components and to an instantaneous reactive current of an instantaneous active current transformed to a two-axis coordinate system. CONSTITUTION:The basic wave component of an instantaneous active current iq is eliminated by an HPF 90 and the higher harmonic component of the current iq is detected. Then the higher harmonic component is added to a DC voltage control current command Vdc via an adder 63, and this computing result is sent to a feedforward control circuit 22 for execution of the feedforward control. Thus a compensated current command value iq* is calculated. Meanwhile an instantaneous reactive current id is sent directly to a feedforward control circuit 21 for execution of the feedforward control. Thus a compensated current command value id* is calculated. The feedforward control can not be attained in the three-phase AC coordinate system, but an effective control is attainable by applying the feedforward control to the higher harmonic components of both currents id and iq transformed in the two-axis coordinate system. Thus the compensating ability is improved between a reactive current and a higher order harmonics.