1. A network for predicting plant outputs of a plant and for receiving control variables that are used to control the plant and measurable state variables of the plant, with the measurable state variables having dependencies on the control variables and unmeasurable external influences, the control network for projecting out the dependencies of the measurable state variables on the control variables, comprising: a residual activation neural network for generating an estimation of the unmeasurable external influences on the plant and having: an input layer for receiving the control variables, an output layer for outputting predicted state variables, a hidden layer for mapping said input layer to said output layer through a representation of the dependencies of the state variables on the control variables to generate said predicted state variables, which said representation is trained on the measurable state variables, and a residual layer for determining as a residual the difference between said predicted state variables and the input state variables, said residual comprising an estimation of the unmeasurable external influences on the plant; and a main neural network having: an input layer for receiving as inputs the control variables and input signals parameterized by said residual, an output layer for outputting a predicted plant output, and a hidden layer for mapping said input layer to said output layer through a representation of the plant as a function of the control variables and said residual.