Hybridization of WLS and LMR: a Robust Solution for Power System State Estimation

Ensuring accurate estimation of the power system states (bus-voltage’s magnitude and angle) is a prime requirement for its protection, monitoring and controlling. Meters might provide wrong measurement readings that could cause deterioration of the estimation performance. Consequently, dealing with such bad data (single or multiple) is one of the major challenges in the field of power system State Estimation (SE). There are some estimators which have the capability of filtering out the bad measurements during the estimation process. This paper presents a novel way of hybridizing two of the eminent estimators: Weighted Least Square (WLS) and Least Measurement Rejected (LMR). The proposed technique has the capability of dealing with different single and multiple bad data scenarios successfully. It also provides a solution to the problem of proper selection of measurement tolerance for LMR estimator. The performance of the proposed estimator is compared with WLS and the robust Weighted Least Absolute Value (WLAV) estimators. IEEE 30-bus and 118-bus systems are used to demonstrate the robustness of the proposed estimator.