| 摘要 |
In a power converter which performs power conversion between plural-phase AC and DC, variation in voltage of the DC capacitor in each converter cell is detected, and when the variation exceeds a predetermined value, a DC voltage command value as a control target value in a DC voltage control unit which controls DC voltage between DC buses is corrected by being increased or decreased. Thus, when AC grid failure occurs, the capacitor voltage of each converter cell is maintained and the operation continuity is improved. |
| 主权项 |
1: A DC power transmission power conversion device comprising:
a power converter including a plurality of leg circuits composed of a positive arm and a negative arm for each phase which are connected in series to each other and have a connection point therebetween connected to an AC line for a corresponding phase, the leg circuits being connected in parallel between positive and negative DC buses, the power converter performing power conversion between plural-phase AC and DC; and a control device for controlling the power converter, wherein each of the positive arm and the negative arm composing each leg circuit is composed of at least one converter cell connected in series, the converter cell is composed of a series unit of a plurality of semiconductor switching elements connected in series, and a DC capacitor connected in parallel to the series unit, the control device performs output control for each converter cell composing the positive arm and the negative arm, the control device includes:
a capacitor voltage control unit for generating a current command value (ipref, ip+ref, ip−ref) for voltage control for each DC capacitor on the basis of voltage (Vcap) of the DC capacitor;a current control unit for, on the basis of the current command value (ipref, ip+ref, ip−ref) from the capacitor voltage control unit, generating a voltage command (Vpc+, Vpc−) for AC current control, of a positive arm voltage command (Vp+) for controlling current flowing through the positive arm and a negative arm voltage command (Vp−) for controlling current flowing through the negative arm; anda DC control unit for, on the basis of DC voltage (Vdc) between the DC buses, DC current (idc) flowing through the DC buses, and a command value (Vdcref, idcref) as a preset control target value, generating a DC voltage command (Vdc*) for DC voltage control, of the positive arm voltage command (Vp+) and the negative arm voltage command (Vp−), and the control device corrects the command value (Vdcref or idcref) to be given to the DC control unit, in accordance with a detected amount of voltage variation in each DC capacitor. |
