Method and control device for controlling an electricity grid

A method for controlling an electricity grid comprising an AC electricity grid and a DC electricity grid coupled thereto via a converter, wherein:

• a) a first load flow in the AC electricity grid is modeled by a first load flow model and a second load flow in the DC electricity grid is modeled by a second load flow model,
• b) the converter controls an active power flow between the AC electricity grid and the DC electricity grid in dependence on a grid voltage of the DC electricity grid, wherein this dependence is adjustable in a control characteristic of the converter by a first coupling parameter,
• c) a first tolerance range for an infeed active power of a generator and/or for an active load of a consumer is read in,
• d) a process for robust optimization of a predefined cost function is performed using the first tolerance range as robust optimization uncertainty, wherein, by the first and second load flow models, the first and second load flows, the active power flow, the grid voltage of the DC electricity grid and also the first coupling parameter are combined and the first coupling parameter is determined in such a way that the cost function is optimized, and
• e) the control characteristic of the converter is set by the first coupling parameter determined in this way.