COMPENSATING DEVICE FOR INSTANTANEOUS REACTIVE POWER

PURPOSE:To absorb the reactive current of another device up to its higher harmonic component with use of a current type converter, by detecting the instantaneous reactive power of said device and utilizing this reactive power for control of a circulating rate and a phase controller. CONSTITUTION:A direct current I detected by a current transformer CTd is compared with a command current Is by a current control circuit Ic. Then a current circulating rate gammad produced by an inverter main circuit In is calculated against a load Ld and applied to a computing element C. At the same time, a circulating rate gammaq received from a reaction current detector gd when an instantaneous reactive current is detected is also supplied to the element C. Thus a circulating rate gamma and a phase angle alpha are calculated by equations I and II. Then the circuit In is controlled via a pulse control circuit Pc by the rate gamma, angle alpha and the output of a synchronizing signal generating circuit SP. The instantaneous reactive power produced by another load Lc is compensated up to its limit with 3-phase circulating rates gammau, gammav and gammaw obtained from an equation III. Then said reactive power can be absorbed up to its higher harmonic component by means of a current converter. Here, theta means a U-phase voltage electrical angle in those equations.