Improved SHGM Robust State Estimation for Power System Considering Complementary Non-smooth Constraints

The state estimation accuracy will be greatly affected when the measurement gross error exists. Schweppe-type generalized M-estimator with Huber psi-function (SHGM) can not completely eliminate the influence of bad data which exists in leverage point. On-load tap changer (OLTC) model has non-smooth characteristics such as limits, which will bring non-smooth complementary constraints. The existing SHGM robust state estimation is limited to deal with complementary constraints. To solve the above problems, this paper proposes an improved SHGM model considering complementary non-smooth constraints. In order to deal with the limits constraints introduced by the voltage control strategy of OLTC, the Fischer-Burmeister (FB) smoothing function is introduced to convert the complementary constraints into equality constraints, which improves the processing ability of SHGM state estimation for non-smooth characteristics. The correctness and practicability of the improved SHGM model are verified by 3-bus and IEEE 18-bus system. The case studies shows that considering the detailed control characteristics of OLTC and introducing FB smoothing function to deal with complementary constraints can improve the ability of SHGM robust state estimation to deal with bad data.