A Robust Distributed State Estimation of AC/DC System With LCC-HVDC Tie Line

A robust distributed state estimation algorithm for AC/DC system with AC tie lines and high voltage direct current (LCC-HVDC) tie lines is proposed. The proposed algorithm consists of robust DC state estimation in the coordinator and robust distributed AC state estimation, and implements sequential solving by exchanging coupling variables of the AC/DC system. For AC state estimation, a distributed state estimation algorithm based on the bilinear algorithm is designed, which can achieve the same accuracy as the centralized algorithm. Robust state estimator based on the exponential absolute value function and exponential square function is suitable for reducing the influence of outliers and can reduce the operation scale by simplifying the nonlinear iterative process in distributed state estimation. Finally, the correctness and effectiveness of the algorithm is verified by simulation of three IEEE 118 bus systems interconnected through AC/DC hybrid tie lines.