Improvements in or relating to hvdc power converters

In the field of HVDC power transmission there is provided a HVDC power converter (10; 70; 80; 100) that comprises a plurality of first switching elements (12) which are arranged to provide a first function within the power converter (10; 70; 80; 100). Each first switching element (12) has a first control unit (22) operatively connected therewith. Each first control unit (22) is programmed to effect switching of the corresponding first switching element (12) and thereby have the first switching elements (12) provide the first function. The plurality of first control units (22) are arranged in communication via a first communication network (44) with a higher level control unit (46) that is configured to provide each of the first control units (22) with switching instructions for the corresponding first switching element (12). The HVDC power converter (10; 70; 80; 100) also comprises a plurality of second switching elements (50) that are arranged to provide a second function within the power converter (10; 70; 80; 100). Each second switching element (50) has a second control unit (52) operatively connected therewith. Each second control unit (52) is programmed to effect switching of the corresponding second switching element (50) and thereby have the second switching elements (50) provide the second function. The plurality of second control units (52) are interconnected with one another via a second communication network (56).