PARALLEL-CONNECTED CONVERTER ASSEMBLY

摘要

A parallel-connected converter assembly (40) comprises: first and second converters (42, 44), each converter (42, 44) including first and second DC terminals, each converter (42, 44) including at least one converter limb extending between the corresponding DC terminals, each converter limb including first and second limb portions separated by an AC terminal (58), each AC terminal (58) connectable in use to an AC voltage (82), each limb portion including at least one director switch connected between the AC terminal (58) and a respective one of the first and second DC terminals, the director switches of the first and second limb portions operable to switch the respective limb portions into and out of circuit between the respective DC terminal and the AC terminal (58); first and second DC transmission media (46, 48) respectively including first and second DC network terminals (78, 80) connectable in use to a DC network, the first DC transmission medium (78) interconnecting the first DC terminals of the converters (42, 44), the second DC transmission medium (80) interconnecting the second DC terminals of the converters (42, 44); and a controller programmed to selectively control the switching of the director switches of each converter limb to switch both of the corresponding limb portions into circuit concurrently to form a current conduction path in the corresponding converter (42, 44), the respective current conduction path configured to carry a current for presentation to the DC network terminals, wherein the controller is further programmed to selectively control the switching of the director switches so that, in an operating cycle of the parallel-connected converter assembly (40), the parallel-connected converter assembly (40) switches between: a first mode in which the respective current conduction path is formed in the first converter (42) and the respective current conduction path is not formed in the second converter (44); and a second mode in which the respective current conduction path is formed in the second converter (44) and the respective current conduction path is not formed in the first converter (42).