The paper considers the approach of using multi-agent models in simulation and decision making of complex systems. Furthermore, an overview of research in the field of multi-agent systems and software platforms for their implementation is carried out. In addition, an analysis of the applicability of intelligent multi-agent systems in the tasks of modelling, optimization and management of energy facilities is performed. This study shows that power industry can use intelligent multi-agent systems not only for the tasks of modelling the interaction of subjects as suppliers and consumers of electricity in the wholesale electricity market and other problems of game theory considering a small number of agents' types. Moreover, intelligent multi-agent systems can be used to model power systems when it is necessary to take into account the deep integration of the systems. This is understood in the work as dependencies at the level of physical processes of generation, transmission, distribution and consumption of electricity, and at the level of interaction between large technological objects and economic entities. At the second level, it is necessary to consider infrastructure linkages and legal regulations for the economic interaction. As an example, the paper considers a hydropower plant. The entity that manages it must take into account not only the features of the station as a complex electrical facility itself, but also the features of the water usage regime, electricity consumption schedules, meteorological factors, etc. In turn, the use of water resources affects the interests of a large number of subjects, which also needs to be reckoned.