| 摘要 |
In the field of high voltage direct current (HVDC) power transmission, a converter (10) comprises three converter limbs (12A, 128, 12C), each corresponding to a respective phase (A, B, C) of the converter (10), each extending between first and second DC terminals (14, 16) and each including first and second limb portions (12A+, 12A-, 12B+, 2B-, 12C+, 120-) separated by an AC terminal (18A, 188, 180). Each limb portion (12A+, 12A-, 12B+, 12B-, 12C+, 12C-) includes a chain-link converter (24A+, 24A-, 24B+, 24B-, 24C+, 24C-) that is operable to provide a stepped variable voltage source, and a primary switching element (Sw1, Sw2, Sw3, Sw4, Sw5, Sw6) to selectively switch the respective limb portion (12A+, 12A-, 128+, 128-, 12C+, 12C-) into and out of circuit. The converter (10) also includes a first controller (32) that is programmed to selectively operate for one converter limb (12A, 12B, 12C) at a time the primary switching element (Sw1, Sw2, Sw3, Sw4, Sw5, Sw6) in each limb portion (12A+, 12A-, 12B+, 12B-, 120+, 20-) thereof to simultaneously switch both the first and second limb portions (12A+, 2A-, 12B+, 128-, 120+, 120-) into circuit and thereby define a fully-conducting converter limb (12A, 12B, 120) to sequentially route via each said fully-conducting converter limb (12A, 128, 120) a DC current demand (Ipc) between the first and second DC terminals (14, 16). |
