Multifunctional energy management systems implement complex tasks of management and control of distributed power facilities with high level of efficiency and reliability. An important component of these systems efficiency is the organization of internal information exchanges between functional modules, which is associated with the structure of the internal intermodule interface. In this work, the problems of organizing standard internal interfaces for intermodule information exchanges are considered. It has been established that standard interfaces are difficult to implement when used in combined architectures of energy management systems, in which the ability to set priorities for processing information from different types of devices is important. The principles of construction and a mathematical model of the internal interface with a combined data bus have been developed. This interface provides an increase in the information parcels transmission speed in multi-module automated energy management systems. The proposed approaches make it possible to implement the priority of processing information parcels for a combined service procedure.