Power network observability: symbolic factorization and spanning trees

Existing algorithms for power network observability determination can be categorized as numerical based, topologically based, or based on symbolic factorization. An examination is made of the relationship among these classes of algorithms. In particular, an equivalence between methods based on symbolic-factorization and topologically based methods is established. The relationship between these methods and numerical rank determination is characterized by introducing the concept of parametric unobservability