Relating to the control of power converters during fault conditions in power transmission networks

A computer-implemented method of controlling a power converter in a power transmission network, the power converter having an alternating current ‘AC’ side electrically connected to an AC network at a point of connection, the method comprising:

• measuring a first AC voltage and/or a first AC current at the point of connection, thereby providing a measured first AC voltage and/or measured first AC current;
• determining, based on the measured first AC voltage and/or measured first AC current, whether a fault condition is present in the AC network;
• setting a current limit for a second AC current output from the AC side of the power converter, by:
• if a fault condition is determined not to be present in the AC network, setting the current limit to be equal to a first current limit value;
• and
• if a fault condition is determined to be present in the AC network, setting the current limit to be equal to a second current limit value, wherein the second current limit value is less than the first current limit value;
• and
• regulating, based on the current limit, a second AC voltage that is output from the AC side of the power converter, such that the second AC current does not exceed the current limit.