Optimal Water-Power Flow Problem: Formulation and Distributed Optimal Solution

TL;DR

This paper introduces a formalized optimal water-power flow problem that integrates water and power system operations, proposing a distributed solution approach to optimize controllable assets while managing complex couplings.

Contribution

It formulates a nonconvex OWPF problem, develops a convex approximation method, and proposes a distributed solver for joint water-power system optimization.

Findings

Effective solution for coupled water-power systems demonstrated

Distributed algorithm enables independent yet coordinated control

Improved operational efficiency in case study

Abstract

This paper formalizes an optimal water-power flow (OWPF) problem to optimize the use of controllable assets across power and water systems while accounting for the couplings between the two infrastructures. Tanks and pumps are optimally managed to satisfy water demand while improving power grid operations; {for the power network, an AC optimal power flow formulation is augmented to accommodate the controllability of water pumps.} Unfortunately, the physics governing the operation of the two infrastructures and coupling constraints lead to a nonconvex (and, in fact, NP-hard) problem; however, after reformulating OWPF as a nonconvex, quadratically-constrained quadratic problem, a feasible point pursuit-successive convex approximation approach is used to identify feasible and optimal solutions. In addition, a distributed solver based on the alternating direction method of multipliers enables water and power operators to pursue individual objectives while respecting the couplings between the two networks. The merits of the proposed approach are demonstrated for the case of a distribution feeder coupled with a municipal water distribution network.