In this paper

a kind of optimization model of minimum additional reactive power capacity for the power network is proposed

which not only considers the constraint for the requirement of reactive power compensation capacity in the related guide rule

but also increases the constraint condition of line power flow etc

including such constraint condition as the node voltage and line power flow etc. Under the operation mode of maximum

middle and minimum load. The model is divided into bi-level sub-model in accordance with feature of the model and the coordinative solution between sub-models is achieved by the use of Bender. Finally

the model and it calculation is verified by taking Jiangsu 500 kV network as an example and the correctness and effectiveness of the result is shown.