1. A method for controlling a control loop for controlling a power of a process power supply, via a control circuit with a controller and a plurality of control channels, wherein each control channel comprises an actual value and a target value of a control variable, wherein the plurality of control channels represent actual and target values for at least two variables selected from a group of variables comprising: forward power, reverse power, and power at a load, respectively, the method comprising: specifying the target values of the control variables; determining the actual values of the control variables; determining a selected control channel from the plurality of control channels based on a selection variable dependent upon the actual values; determining a selected control difference from a target value and an actual value of the selected control channel; controlling the control loop and each control channel with the selected control difference of the selected control channel; and controlling the power supply with the control loop, wherein the selection variable is normalized for at least one of the control channels to the target value of the corresponding control channel to form a normalized selection variable and wherein determining the selected control channel comprises determining the selected control channel from the plurality of control channels on the basis of a comparison of the normalized selection variable with at least one further similar normalized variable of one of the other control channels.