Bad data analysis using the composed measurements errors for power system state estimation

In this paper, a topological/geometrical based approach is used to define the undetectability index (UI), which provides the position of a measurement related to the range space of the Jacobean matrix of the power system. The higher the value of this index, for a measurement, the closer it will be to the range space of that matrix, that is, the error in measurements with high UI is not reflected in their residuals, thus masking a possible gross error those measurements might have. Using the UI of a measurement, the possible gross error the state estimation process might mask is recovered; then the total gross error of that measurement is composed and used to the gross error detection and identification test. The gross error processing turns out to be very simple to implement, requiring only a few adaptations to the existing state estimation software. The IEEE-14 bus system is used to validate the proposed gross error detection and identification test.