Impact of employing state estimation of distribution networks on state estimation of transmission networks

The smart meters installed throughout the distribution networks in some regions have opened an opportunity to have reliable State Estimation (SE) at the distribution level. The reliable distribution system SE results can also be used to improve the accuracy and reliability of SE in transmission networks. This paper studies the impact of employing the results of distribution network SE as additional measurements in transmission network SE. It is shown that the observability of transmission networks can be restored using smart meters when it is unobservable. Moreover, improvement in the robustness of SE in transmission networks is studied by monitoring the condition number of the gain matrix in the Weighted Least Squares (WLS) SE process. Finally, it is demonstrated that the accuracy of SE in transmission level can be improved using the results of SE on distribution level.