Control method null of self-excitation type reactive power

摘要

PURPOSE: To obtain the self-excited reactive power compensation device of inverter specifications which is simple in control circuit constitution and reducible in the cost and has high reliability. ;CONSTITUTION: System phase voltages VR, VS, and VT and load currents iR, iS, and iT of a three-phase system bus are multiplied and added to find three- phase active power P, from which a low-pass filter(LPF) 9 finds a DC signal P' corresponding to fundamental wave balanced active power as a three-phase balanced component. On the other hand, sine wave signals SR, SS, and ST which are synchronized with the three-phase system phase voltages VR, VS, and VT and have unit amplitudes balanced are found by a phase-locked loop(PLL) 10 and a sine wave generating circuit 11 from the three-phase system voltages, and multiplied by a gain K found from the DC signal P', phase by phase, to find balanced active current components iRP, iSP, and iTP which are in phase with one another, and those are subtracted from the load currents iR, iS, and iT of the respective phases to detect compensating current command values iRC, iSC, and iTC.;COPYRIGHT: (C)1996,JPO