Proper network partition for secondary voltage control is the prerequisite for the application of three levels or “soft” three levels voltage control. Good partition should satisfy the conditions that each partition contains at least one reactive power source while maintaining connexity itself. This paper proposes a three-stage network partition method for secondary voltage control based on network structure and electrical distance. Firstly

the method proposed merges the reactive power source nodes connected by radial branches into one and the same partition according to the network structure. Secondly

the controlled nodes are classified into two types

and then merged into the partition to which the nearest reactive power source in electrical distance belongs while keeping the connexity of partitions. Finally

an agglomerative analysis is made on the initial partitions according to WARD distance to determine the final network partitions. Allowing for merger to be performed only between the connected partitions guarantees the connexity of the final partition while greatly reducing the scale of agglomerative computation. The method proposed meets the demand of secondary voltage control as the partition results are related only to the network structure while having nothing to do with the operation conditions

such as power flow distributions. The partition results of an IEEE 39-bus system and Yunnan power system have verified the rationality and efficiency of the proposed method

showing that the method is of definite application value to the secondary voltage control of power systems. This work is supported by National Key Technologies R&D Program (No. 2013BAA01B02).