Power transmission network

A power transmission network comprises a single-phase or multi-phase AC electrical system, a converter including at least one AC terminal, a point of common coupling, a phase reactance connecting the point of common coupling to the or each AC terminal of the converter, and at least one power transmission medium to interconnect the point of common coupling and the AC electrical system. The power transmission network further includes a converter controller programmed to: €¢ process the voltage and current at the point of common coupling to compute a state vector corresponding to the power transmission network; €¢ derive a converter demand by combining the computed state vector with a plurality of control parameters, wherein the plurality of control parameters includes the capacitance of the power transmission medium or media presented at the point of common coupling and the impedance of the phase reactance; and €¢ operate the converter in accordance with the converter demand to control the converter voltage at the or each AC terminal and/or the voltage at the point of common coupling so as to inhibit any perturbation in the converter voltage from a target converter voltage or range resulting from the interaction between the capacitance of the power transmission medium or media and the impedance of the phase reactance.