In order to adapt to the increasingly complex structure of interconnected power grid and the hierarchical and partitioned management modes

the distributed state estimation calculation for interconnected systems using partition and decoupling by tie-line are adopted. Considering the balance of estimation accuracy and efficiency

this paper proposes a distributed state estimation algorithm combining the state estimation of tie-line extended area and the sensitivity matrix coordination method. The whole idea of the distributed state estimation is designed in two parts. On one hand

the state estimation and the sensitivity matrix solution of each region in the partition layer is independently performed once the interconnected power grid is decoupled by regional tie-lines. Simultaneously

the tie-line estimation area in coordination layer is dynamically constructed and the parallel state estimation calculation is completed. On the other hand

the coordinated correction calculation for the mismatch of boundary estimation value in each sub-region is performed in parallel according to the tie-line estimated values and sensitivity matrixes distributed by the coordination layer. Finally

the calculation examples of the IEEE 118-bus

IEEE 30-bus and an actual interconnected power system show the superiority of the proposed algorithm

in terms of the estimation accuracy

the converging speed and the calculation efficiency. The proposed algorithm avoids the large-scale integrated state estimation calculation and solves the bottleneck problems of state estimation of large-scale power system with local observability or convergence issues by performing independent parallel calculation.