  This paper introduces a micro-nexus of water and energy which can be
considered as one of the physical infrastructures of the future
building/city/village systems. For the electricity side, an alternating current
(AC) power flow model integrated with battery energy storage and renewable
generation is adopted. The nonlinear hydraulic characteristics in pipe networks
is also considered in the proposed micro water-energy nexus (WEN) model.
Integer variables are involved to represent the on/off state of pumps. Base on
the proposed nexus model, a co-optimization framework of water and energy
networks is developed. The overall co-optimization model is a mixed-integer
nonlinear programming problem which is tested on a waterenergy nexus which
consists of the IEEE 13-bus distribution system and a 8-node water distribution
network. The simulation results demonstrate that the cost-efficiency of the
co-optimization framework is higher than optimizing two systems independently.
