Optimal independent but coordinated operation of interconnected power, natural-gas, and district-heating distribution systems

Traditionally, power, natural-gas, and district-heating distribution systems have been planned and operated independently. However, the increasing presence of distributed natural-gas-fired generating units, heat pumps units, power-to-gas facilities, and combined heat and power units create an interdependency where the operational decisions of any system affect the operation of the other systems. We analyze centralized and decentralized operations of the three distribution systems and discuss under which conditions centralized and decentralized operations are equivalent. We find this equivalence by replacing each system operation problem with its optimality conditions and comparing them with the optimality conditions of a centralized operation. Using a realistic case study, we quantify the gains resulting from different levels of coordination. Equilibria, i.e., joint optimal solutions for the three systems, are found using an iterative convexification technique, which is novel in the context of this paper. An advantage of the proposed model lies in its potential to expand across a range of interconnected energy systems, which in turn, enables the identification of the equivalences between centralized and decentralized operations.