A TRACKING STATE ESTIMATOR FOR NONSINUSOIDAL PERIODIC STEADY-STATE OPERATION

This paper presents a tracking state estimator for systems operating u nder nonsinusoidal but periodic steady state conditions. Such operatin g states are being frequently observed in today's power systems due to the emerging nonlinear loads and power conditioning devices. Measurem ent equations are derived in discrete time and the sampling frequency is chosen according to the highest harmonic of interest. The proposed estimator is designed to be computationally efficient by transforming the measurement equations in a special manner so that the sparsity of the corresponding discrete time matrix equations is significantly enha nced. Zero injection constraints are also included to take advantage o f the increased redundacy. The paper presents results of simulations u nder both normal measurement noise as well sis with gross errors exist ing in the measurements. Performance of the developed algorithm is eva luated both in terms of cpu time and accuracy based on the simulations .