On harmonic state estimation and the evaluation of harmonic power contributions from sources

A new approach to harmonic state estimation is proposed by firstly classifying the network nodes into four types. Classification of a particular node into one of the four types is based on the availability or otherwise of node voltage and nodal harmonic injection current measurement at the node. Algebraic expressions to determine all the remaining unknown node harmonic voltages and nodal harmonic injection currents are then derived. The condition for minimum measurement set is derived which will lead to the complete determination of the harmonic state of the network. This Basic Approach is compared with the Singular Value Decomposition method proposed for harmonic state estimation. An application of the Basic Approach is also included, the aim of which is to assess the degree of dominance of particular harmonic source to harmonic real power flow in loads. The method is based on the construction of a set of sensitivity indices which relates the change in the real harmonic load power of a given node to that of the harmonic current injection from each of the sources.