Abstract: A method for monitoring system variables of an energy distribution or transmission grid includes measuring at least one of the system variables of a system variable vector, estimating the system variables using system equations reflecting a dynamic and static behavior of the system variables on the grid, and displaying the estimated system variables on a screen. To improve the accuracy of the estimated system variables, maximum log-likelihood estimates of the system variables are determined based on minimizing an objective function which includes a probability density function of the corresponding measurement error for each of the system variables for which measurements are taken. The objective function also includes system equations having as the system variable vector at least all of the system variables for which measurements are taken, and for at least one parameter of the state equations a corresponding predefined range of parameter values expressed as a parameter uncertainty.