Harmonic state estimation for distribution systems based on optimization models considering daily load profiles

This paper presents a novel static harmonic state estimation methodology for power distribution networks based on optimization models, assuming a limited number of synchronized phasor measurement units (PMUs) strategically allocated along the feeders. Optimization problems are formulated individually for each harmonic order to be analyzed in regular time intervals, with the purpose of estimating daily load profiles and harmonic components from dominant sources. Active and reactive powers are treated as inequality constraints for buses which are not monitored in real time by PMUs. The optimization problems are solved by safety barrier interior point method, in which a relaxation parameter is introduced for the constraints which reach their corresponding upper/lower bounds in order to avoid constraints violation. Simulations are carried out using a 69-bus power distribution system. Results are presented and discussed to prove the efficiency of the proposed method, including sensitivity analysis for parameters used by the algorithm.