A hybrid nonlinear - least squares estimation of harmonic signal levels in power systems

It is expected that guides and recommended practices will be adopted in the United States for the limitation of harmonic currents and voltages in electric power systems. Accordingly it is of interest to use measurements and topological/mathematical methods to identify signal levels which do not comply with these guides and standards. One such methodology is based on measurements state estimators, and system modelling. This technique is described in this paper and an illustration is given for its application. Specifically, hybrid of nonlinear - least squares method is used for state estimation. This estimation theory is used to calculate (estimate) bus voltages and line currents which can not (or, simply, are not) measured directly. The basis for the least squares estimator is the Kirchhoff current law, and the basis for the nonlinear technique is minimum mismatch power.