The flexible and diversified trend of development of the intelligent distribution network is making the interaction between the transmission and distribution network increasingly appreciable

hence higher requirements are put forward on the situation awareness of distribution network. To improve the situation awareness ability

a fast situation awareness method for distribution network coordinated with transmission grid is proposed. Firstly

the state of transmission network for estimating distribution network load variation is calculated. Secondly

the Thevenin equivalent method is employed and the equivalent parameters of transmission grid from the root node of distribution network are identified. Finally

the transmission grid is connected to the distribution network to become aware of the situation of the distribution network for load variation. There is no need of repeated information exchange between transmission and distribution network with the proposed method compared with the iteration method. On the basis of the proposed method

the trajectory of the static voltage stability margin index of distribution network can be predicted through multi-step-ahead states forecast

and then the static voltage security situation can be estimated based on this trajectory. The simulation results show its feasibility and effectiveness. This work is supported by National Natural Science Foundation of China(No. 51177091)and State Grid Corporation of China.