VOLTAGE SOURCE CONVERTER

In the field of voltage source converters for use in high voltage direct current (HVDC) power transmission and reactive power compensation, there is provided a voltage source converter which comprises a plurality of converter limbs connected in series between first and second DC terminals that are connectable in use to a DC network. Each converter limb includes first and second series connection points between which extends a longitudinal chain-link converter that is operable to provide a stepped variable voltage. Each first series connection point is electrically connected with a corresponding first AC connection terminal via a first transverse branch. Each second series connection point is electrically connected with a corresponding second AC connection terminal via a second transverse branch. The first and second AC connection terminals together define an AC connection that is connectable in use to a respective phase of an AC network. At least one transverse branch in each converter limb includes a transverse circuit which has therein a transverse chain-link converter that is operable to provide a stepped variable voltage.