A line commutated converter, LCC, for a high-voltage direct current power converter, the LCC comprising at least one LCC bridge circuit for connection to at least one terminal of a DC system , each bridge circuit comprising at least two arms , each arm associated with a phase of an AC system, each arm comprising: one or more upper thyristor valves (TY1, TY3, TY5) and one or more lower thyristor valves (TY4, TY6, TY2) connected in series; a branch extending from between the upper and lower thyristor valves; a parallel capacitor module comprising a parallel capacitor (CapYac, CapYab, CapYbc) being connected in parallel directly between at least one pair of branches comprising a first branch and a second branch; characterized in that during commutation of a flow of current in the first branch to a flow of current in the second branch, the at least one parallel capacitor (CapYac, CapYab, CapYbc) is configured to discharge current into the second branch in the same direction as the flow of current in the second branch; wherein the line commutated converter further comprises a first controllably insertable capacitor module , wherein the first controllably insertable capacitor module is configured to insert at least one first insertable-series capacitor (CapYa, CapYb, CapYc) in series with each branch; and wherein the line commutated converter further comprises an inductor module comprising at least one current limiting inductor (LYa, LYb, LYc) in series with each branch, such that a varying extinction angle for the LCC can be achieved, thereby supplying a reactive power to the AC system; the inductor module configured to reduce the time period taken for commutation between thyristor valves (TY1, TY3, TY5, TY4, TY6, TY2) to complete, the capacitances of the parallel capacitor module being selected so that a first electrical path through the parallel capacitor module has a lower impedance at harmonic frequencies than a second electrical path through the inductor module to the AC system in order to restrict the transmission of harmonic frequencies to the AC system. one or more upper thyristor valves (TY1, TY3, TY5) and one or more lower thyristor valves (TY4, TY6, TY2) connected in series; a branch extending from between the upper and lower thyristor valves; a parallel capacitor module comprising a parallel capacitor (CapYac, CapYab, CapYbc) being connected in parallel directly between at least one pair of branches comprising a first branch and a second branch; characterized in that during commutation of a flow of current in the first branch to a flow of current in the second branch, the at least one parallel capacitor (CapYac, CapYab, CapYbc) is configured to discharge current into the second branch in the same direction as the flow of current in the second branch; wherein the line commutated converter further comprises a first controllably insertable capacitor module , wherein the first controllably insertable capacitor module is configured to insert at least one first insertable-series capacitor (CapYa, CapYb, CapYc) in series with each branch; and wherein the line commutated converter further comprises an inductor module comprising at least one current limiting inductor (LYa, LYb, LYc) in series with each branch, such that a varying extinction angle for the LCC can be achieved, thereby supplying a reactive power to the AC system; the inductor module configured to reduce the time period taken for commutation between thyristor valves (TY1, TY3, TY5, TY4, TY6, TY2) to complete, the capacitances of the parallel capacitor module being selected so that a first electrical path through the parallel capacitor module has a lower impedance at harmonic frequencies than a second electrical path through the inductor module to the AC system in order to restrict the transmission of harmonic frequencies to the AC system. <EOS>