The dispatching operation of modern power grid has the characteristics of complexity and uncertainty

which poses a severe challenge to the traditional dispatching mode based on experience. By introducing risk consequences calculation into large-scale power grid dispatching operation

the concept of operation state and operation developing state is proposed for each of the operating steps decomposed from the dispatching order

and the corresponding calculation model each for the operation state and operation developing state is built. In terms of assessment indices

overload

overload power of control section

voltage violation and loss of load are used as four indices to describe power grid dispatching operation risk. Then normalization and commensurability are used to evaluate the risk consequences of each operation step and of the whole dispatching order. Finally

the proposed model is used to assess operation risk of Guangdong power grid. It is proved that the proposed model is effective and feasible for large-scale power grids. During the risk consequence assessment

high-risk operation steps of the dispatching order can be found out

which provides an identification method to discover potential risk right from the formulation of the dispatching order at the beginning of power grid dispatching. This work is supported by Scientific Research Project of China Southern Power Grid (No. K-GD2014-1001)and National Natural Science Foundation of China (No. 50907023).