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. A method of using measurements and topological/mathematical methods to identify signal levels that do not comply with these guides and standards is described. The methodology is based on measurements, state estimators, and system modeling. An illustration of its application is given. A hybrid nonlinear-least-squares method is used for state estimation. This estimation theory is used to calculate (estimate) bus voltages and line currents which cannot be (or 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