Power transmission network

A power transmission network comprising:

• a plurality of converters interconnected via a plurality of electrical elements;
• at least one power flow router, the or each power flow router being operatively connected to at least one of the plurality of electrical elements, the or each power flow router being configured to be controllable to selectively control current flow in at least one of the plurality of electrical elements so as to direct power between two or more of the plurality of converters;
• and
• a controller configured to selectively control the plurality of converters and the or each power flow router to control power flow in the power transmission network;
• wherein the controller is configured to:
• carry out a first mathematical optimisation to determine one or more optimal operating set points of one or more of the converters;
• after carrying out the first mathematical optimisation, carry out a second mathematical optimisation to determine one or more optimal current flows in the plurality of electrical elements;
• and
• control the one or more of the converters in accordance with the or each determined optimal operating set point, and control the power flow router or at least one of the power flow routers to achieve the or each determined optimal current flow in the plurality of electrical elements.