Algorithms to solve qualitative problems in power system state estimation
This paper presents two algorithms. The first one allows the identification of critical measurements and critical sets. The second algorithm allows, in a straight and fast way, observability analysis and restoration as well as the updating of the measurements qualitative characteristics in the situation of measurements losses. For such purpose, a Base Case Measurement Set is considered. This measurement set contains all the installed and virtual measurements. The proposed algorithms work in a straightforward manner, using a new way based on the relationship between measurements and equivalent states. These states are obtained via triangular factorization of the Jacobian matrix, characterizing the algorithms as numerical. The sparse structure of such matrix allows the use of sparse techniques speeding up the process. The algorithms were tested in the IEEE-14-bus system, as well as in two realistic systems of Brazilian utilities. The results proved the algorithms are reliable, easy to implement and fast.
state estimation critical measurements critical sets observability analysis