Initially, the physical phenomenon, based on that, this parameter is affected and how it can be controlled are explained. This func-tion makes it possible to measure the absorption curve of the EPR The frequency control includes two subproblems FREQUENCY RANGE Automatic control systemsNormal operation (In SwedenHz)Disturbance reserve (In SwedenHz) Disconnection of interruptible loads (export on HVDC lines, electric boilers, heat pumps, pumped storage hydro (In SwedenHz) Automatic load shedding (