Load signatures development via harmonic current vectors

Abstract

This paper examines the development of load signatures based on odd order harmonic current vectors. A measurement setup is developed, and measurements concerning stand-alone and combined operation of several appliances in steady state have been performed using the fundamental voltage phase angle as the angular reference. The proposed load signatures consist of the first three harmonic order currents and each one of them is considered a vector quantity. An alternative formulation that considers only the projections of these vectors on the x-axis is also proposed in order to simplify the load signatures structure. The disaggregation scheme regarding the NILM approach assumes that the contribution of each appliance's harmonic current to the aggregated one, under simultaneous operation of specific appliances, is linear and results by summation of the respective components. Results indicate that the accuracy of this approach is higher when harmonic currents are treated as vectors and their phase angle is taken into account in the computations. The proposed load signature formulation is simple, the linear approach for the disaggregation scheme is kept regardless the harmonic current vectors consideration and the results seem to be more accurate.