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A method for topology error identification based on collinearity tests involving Lagrange multipliers and the columns of the corresponding covariance matrix is presented. It relies on a geometric interpretation of the multipliers associated with the equality constraints that model circuit breaker status in generalized state estimation. The method is conceptually simple, and its implementation requires little computational effort, therefore being suitable for real-time applications. Results of several simulated cases conducted at the substation level on a real-life test system based on a subnetwork of the Brazilian Northern power system are used to illustrate the performance of the proposed technique. Index Terms--Bad data analysis, power system real-time operation, power system state estimation.

The conventional topological observability analysis based on the network representation at the bus-branch level is generalized to include the explicit modeling of circuit breakers and switches. This generalization is motivated by the present trend toward a more detailed representation (at the substation level) of the power network in state estimation studies. After developing the topological representation of switching branches according to their current status, it is shown that existing algorithms for observability and criticality analysis can be adapted to solve the extended problem. Results of the proposed approach for generalized observability and criticality analysis are validated by checking their consistency with numerical state estimation results. Index Terms--Graph theoretic methods, power system observability analysis, power system state estimation.