Power network observability: the assessment of the measurement system strength

This is the authors' abstract. We don't add key points for this paper.

Two main ideas concerning power network observability analysis are developed, based on the fact that measurement-to-branch incidence matrix M, and node-to-branch incidence matrix A are both totally unimodular matrices. The first idea may be stated as follows: if the product matrix W=MA/sup t/ is considered, where W is the measurement-to-node incidence matrix, its Gramian G(W)=det(W/sup t/W) is nonzero for observable networks, and equals zero for unobservable networks. The second idea may be stated as follows: for a given network and measurement system the Gramian of W, G(W)=det(W/sup t/W) is an invariant (there is one matrix M and n distinct matrices A), therefore there are n distinct matrices W.>