Two-Stage Linear State Estimation for Active Distribution Networks

Linear state estimation (SE) formulation play an important role in real-time distribution network management. The voltage magnitude, active power, and reactive power measurements are transformed to linear measurements with large initial node voltage errors when SE under a rectangular coordinate system. In order to solve this problem, a linear state estimation under a polar coordinate system is proposed to obtain a sufficiently accurate complex node voltage in the first stage, and then nonlinear measurements are transformed to linear measurements with the complex node voltage. Bad data identification can be embedded in this stage. In the second stage, linear SE under a rectangular coordinate system are used. The proposed two-stage linear SE is validated on balanced 33, 70, 84, 119, 874-node distribution networks and IEEE 13, 34, 37, 123 unbalanced test feeders.