DC/AC power converter with DC side double frequency pulsation suppression caused by AC side faults

摘要

A commanded negative-sequence current is added to a commanded current so as to suppress double-frequency pulsation on the DC side. The commanded negative-sequence current is found from three values (i.e., the detected value of positive-sequence voltage vector on the power-supply side, the detected value of negative-sequence voltage vector, and a commanded positive-sequence current). Thus, the pulsations which occur on the DC side of a semiconductor power converter and which have a frequency double the power-supply frequency are suppressed even when the AC power supply is at fault while assuring stability of the current control system, thus permitting stable and continuous operation.

主权项

1. A semiconductor power converter comprising:
a power converter including arms constituting three-phase bridge connections having AC-side terminals which are connected with a three-phase AC system via an inductance, said arms having self-extinguishing semiconductor devices connected thereto, said self-extinguishing semiconductor devices being IGBTs or combinations of MOSFETs and free-wheeling diodes; a voltage-measuring device for measuring an AC voltage developed across the three-phase AC system; a current-measuring device for measuring an AC current flowing through the power converter; a phase detector for detecting phase θ of the AC voltage; an AC current adjuster for outputting commanded pulses to the power converter based on a commanded active current value Iqref and a commanded reactive current value Idref along two axes and on an output from the AC current-measuring device; a two-phase voltage vector calculator for receiving a measured value of voltage developed across the three-phase AC system and calculating a positive-sequence voltage vector Vp and a negative-sequence voltage vector Vn; and a phase calculator for calculating and outputting a positive-sequence voltage phase θp from a reference phase θ for the two-phase voltage vector calculator and from the positive-sequence voltage vector Vp; wherein said AC current adjuster calculates a commanded positive-sequence current vector Ipref from the commanded two-axis current values Iqref and Idref, calculates a commanded negative-sequence current vector Inref using the relationship, Inref=−(Vn/Vp)×Ipref, calculates commanded three-phase current vectors Iaref, Ibref, and Icref from the commanded positive-sequence current vector Ipref and from the commanded negative-sequence current vector Inef, calculates commanded three-phase current values from the commanded three-phase current vectors and from the positive-sequence voltage phase θp, and outputs commanded pulses to bring the commanded three-phase current values into agreement with the measured values of AC current.