Owing to slow calculation speed and low accuracy of state estimation in unbalanced three-phase complex active distribution networks

a state estimation method based on multi-criteria partition and weighted least square-primal dual interior point method(WLS-PDIPM)hybrid algorithm is proposed. A multi-criteria optimal model is developed for state estimation in an active distribution network

in which the configuration of real-time measurement

virtual measurement and pseudo measurement are analyzed. The scale equilibrium

the measurement redundancy equilibrium and the average error pseudo measurement equilibrium of each sub-region after partition are also considered. The computation burden is reduced by the decoupling of sub-regions

which is achieved by the full measurement point of the advanced metering infrastructure(AMI). A WLS-PDIPM hybrid algorithm is used to solve the objective function of each sub-region after partition. This method combines the advantages of the basic weighted least squares(WLS)method and primal dual interior point method(PDIPM)

based on which the 'accuracy of the algorithm is improved and the computation time reduced. Simulation results show that the proposed method can achieve rational partition in an active power distribution network

while calculation speed and accuracy of the state estimation are largely improved. This work is supported by National Natural Science Foundation of China(No. 51377162).