Patent ID: 8305782

Claim:
A method for providing redundant control of at least one controllable current valve provided in a converter of a high voltage power transmission system, the method comprising: sending a first valve control signal for said at least one controllable valve and an associated first active/standby indicator from a first converter control unit to a first valve control element of a valve control unit, sending a second valve control signal for said at least one controllable valve and an associated second active/standby indicator from a second control element of said valve control unit, wherein an active/standby indicator indicates if a corresponding converter control unit is an active or standby converter control unit and only one active/standby indicator indicates an active converter control unit at a given point in time, such that two active/standby indicators cannot simultaneously indicate an active converter control unit, receiving, with said valve control unit, said active/standby indicators and said first and second valve control signals, selecting, with said valve control unit, a valve control signal to be used for controlling said current valve if the associated active/standby indicator indicates an active converter control unit, wherein the selecting comprises determining by the first valve control element if said first valve control signal is to be applied based on the first active/standby indicator, and determining by the second valve control element if said second valve control signal is to be applied based on the second active/standby indicator, wherein the determinations are performed in parallel independently of each other and controlling said current valve using said selected valve control signal.