The problem of the power consumption forecast calculation is solved for all time intervals with the subsequent increase in the accuracy while the prediction intervals are decreasing. The lack of complete information on all types of node loads of the controlled power system makes it necessary to solve the problem of their determination. The composition of the nodes and methods of loads modelling are determined by the equivalent circuit of the power grid applied. A System of Node Load Models that provides a solution of the whole complex of forecasting problems on the basis of a common methodological basis, using nonlinear additive models is proposed in the paper.