A line commutated converter, LCC, for a high-voltage, direct current, HVDC, power converter, the LCC comprising at least one bridge circuit (8, 10) for connection to at least one terminal of a DC system, each bridge circuit (8, 10) comprising a plurality of arms (12, 14, 16), each associated with a respective phase of an AC system, each arm (12, 14, 16) comprising: an upper (TY4, TY6, TY2) and lower (TY1, TY3, TY5) thyristor connected in series; an associated branch (23a, 23b, 23c) extending from between the upper (TY4, TY6, TY2) and lower (TY1, TY3, TY5) thyristors to a connection to the respective phase of the AC system; and characterised by comprising: at least one capacitor module (24a, 24b, 24c) for each phase, the or each capacitor module (24a, 24b, 24c) operable to allow a first capacitor (CapYa, CapYb CapYc) to be inserted into the associated branch (TY4, TY6, TY2) of the bridge circuit in both polarities; and wherein the capacitor modules (24a, 24b, 24c) are operable to insert a first capacitor (CapYa, CapYb, CapYc) into the bridge circuit (8, 10) during a first commutation period, wherein commutation is provided from a first initially conducting thyristor in a first initially conducting arm to a first subsequently conducting thyristor in a first subsequently conducting arm; and wherein the capacitor modules (24a, 24b, 24c) are operable to insert the first capacitor (CapYa, CapYb, CapYc) into the first initially conducting arm to increase an effective commutation voltage, thereby reducing a current flowing through the first initially conducting thyristor and charging the first capacitor (CapYa, CapYb, CapYc) an upper (TY4, TY6, TY2) and lower (TY1, TY3, TY5) thyristor connected in series; an associated branch (23a, 23b, 23c) extending from between the upper (TY4, TY6, TY2) and lower (TY1, TY3, TY5) thyristors to a connection to the respective phase of the AC system; and characterised by comprising: at least one capacitor module (24a, 24b, 24c) for each phase, the or each capacitor module (24a, 24b, 24c) operable to allow a first capacitor (CapYa, CapYb CapYc) to be inserted into the associated branch (TY4, TY6, TY2) of the bridge circuit in both polarities; and wherein the capacitor modules (24a, 24b, 24c) are operable to insert a first capacitor (CapYa, CapYb, CapYc) into the bridge circuit (8, 10) during a first commutation period, wherein commutation is provided from a first initially conducting thyristor in a first initially conducting arm to a first subsequently conducting thyristor in a first subsequently conducting arm; and wherein the capacitor modules (24a, 24b, 24c) are operable to insert the first capacitor (CapYa, CapYb, CapYc) into the first initially conducting arm to increase an effective commutation voltage, thereby reducing a current flowing through the first initially conducting thyristor and charging the first capacitor (CapYa, CapYb, CapYc) at least one capacitor module (24a, 24b, 24c) for each phase, the or each capacitor module (24a, 24b, 24c) operable to allow a first capacitor (CapYa, CapYb CapYc) to be inserted into the associated branch (TY4, TY6, TY2) of the bridge circuit in both polarities; and wherein the capacitor modules (24a, 24b, 24c) are operable to insert a first capacitor (CapYa, CapYb, CapYc) into the bridge circuit (8, 10) during a first commutation period, wherein commutation is provided from a first initially conducting thyristor in a first initially conducting arm to a first subsequently conducting thyristor in a first subsequently conducting arm; and wherein the capacitor modules (24a, 24b, 24c) are operable to insert the first capacitor (CapYa, CapYb, CapYc) into the first initially conducting arm to increase an effective commutation voltage, thereby reducing a current flowing through the first initially conducting thyristor and charging the first capacitor (CapYa, CapYb, CapYc)