The article presents practical questions of software developing for system of structural and functional analysis of electric power supply systems (ESS) in oil companies. Software structure is described and internal structure and functions of each software element are considered. Software package includes four modules. Energy object data storage includes all data connected with ESS. Energy efficiency estimation module calculates current electric grid parameters an estimates energy efficiency of existing ESS structure. Energy efficiency control module is used for making recommendations on improving structure and functionality of existing ESS to achieve high energy efficiency under given constraints. User interface provides interaction between all modules of software package and end user. The approaches for energy efficiency analysis and control are discussed. The approach for planning arrangements on energy efficiency increasing is suggested.