An integer-arithmetic algorithm for observability analysis of systems with SCADA and PMU measurements

This paper presents an efficient numerical method for observability analysis of systems including both conventional (SCADA) measurements and synchronized phasor (PMU) measurements, using integer preserving Gaussian elimination of integer coefficient matrices. The observable islands are identified in a noniterative manner, by performing backward substitutions on the integer triangular factors of the integer gain matrix. Multiple placement of conventional and phasor measurements for a system that is found to be unobservable is done by a direct method, using the integer triangular factors of a Gram matrix associated with a reduced size Jacobian matrix. Since all computations performed are exact, no round-off error, numerical instability, or zero identification problems occur. The IEEE 14-bus system is used to illustrate the steps of the proposed method. Test results for the IEEE 300-bus and the FRCC 3949-bus systems are provided to demonstrate the features of the proposed algorithms.

► Efficient observability analysis method for systems composed of SCADA and PMU measurements, using the integer factors of integer coefficient matrices. ► Observable islands are identified in a noniterative manner and additional measurements for placement are provided by a direct method. ► The proposed method does not use floating-point computations is not prone to rounding errors. ► The proposed algorithms are computationally very attractive, yet simple to implement in existing state estimators by minor modifications to the existing sparse factorization and substitution operations.