Observability analysis of electric networks considering branch impedance

This paper presents an analytical method to analyze the effect of X to R ratio as well as impedance value of branches on observability of a network based on un-decoupled formulation of state estimation (SE) and null space of matrices. The results showed that the X to R ratio of branches had no effect on the observability of networks. In addition, it was shown that observability of some networks was affected by impedance values while some others were not affected. In addition, for branch observability analysis of radial network, a simple and quick method is developed. Illustrative examples of the network under transmission and distribution voltages demonstrate the effectiveness of the proposed methods.

Research highlights
► The effect of the X to R ratio of branches on network observability is presented.
► The effect of the impedance value of branches on network observability is investigated.
► The X to R ratio of branches has no effect on the observability of every network.
► A new method is developed to study the effect of impedance values on observability.
► A simple method is proposed for branch observability of radial networks.