A VSC converter comprises in each valve one first semiconductor device (24) of turn-off type with a voltage blocking capacity rating of a first, high level and connected in parallel therewith a series connection of a plurality of second semiconductor devices (25-29) of turn-off type with a voltage blocking capacity rating of a second, lower level. A control arrangement (23) of the converter is configured to switch a said valve into a conducting state starting from a forward biased blocking state of the valve by controlling the second semiconductor devices to be turned on and then the first semiconductor devices to be turned on with a delay, and at the end of the conducting state to turn off the first semiconductor device in advance of turning the second semiconductor devices off.