Distributed Optimal Power Flow for Smart Microgrids

Abstract

Abstract-Optimal power flow (OPF) is considered for microgrids, with the objective of minimizing either the power distribution losses, or, the cost of power drawn from the substation and supplied by distributed generation (DG) units, while effecting voltage regulation. The microgrid is unbalanced, due to unequal loads in each phase and non-equilateral conductor spacings on the distribution lines. Similar to OPF formulations for balanced systems, the considered OPF problem is nonconvex. Nevertheless, a semidefinite programming (SDP) relaxation technique is advocated to obtain a convex problem solvable in polynomial-time complexity. Enticingly, numerical tests demonstrate the ability of the proposed method to attain the globally optimal solution of the original nonconvex OPF. To ensure scalability with respect to the number of nodes, robustness to isolated communication outages, and data privacy and integrity, the proposed SDP is solved in a distributed fashion by resorting to the alternating direction method of multipliers. The resulting algorithm entails iterative message-passing among groups of consumers and guarantees faster convergence compared to competing alternatives.

Investigation of Maximum Possible OPF Problem Decomposition Degree for Decentralized Energy Markets

“…Our test systems include the 24, 57, 118 and 300 bus systems, and a 707 bus system based on the UK network. The method has been applied before in power systems, but compared to [21] we focus in non-convex OPF formulations in meshed networks. Compared to [15,16] we use a problem reformulation introduced in [22] extended to different decomposition structures with respect to demand disaggregation.…”

Three-Phase Optimal Power Flow for Study of PV Plant Distributed Impact on Distribution Systems

“…Among them can be cited [6] which proposes a solution for an unbalanced FPO via the Quasi-Newton method; [7] which considers discrete control operations such as capacitor switching and taps adjustment of OLTCs; [8], based on semidefinite programming; [9] which extends the TOPF based on current injections for optimization of n-conductors systems and, [10] which achieves optimal adjustment of capacitor banks and voltage regulators to minimize active network loss. Some papers also present studies on the impact of distributed PV generation in the system [5,11].…”

Integrated optimal power flow for distribution networks in local and urban scales

“…It features locally produced, stored, and consumed cleaner energy, higher renewable penetration and less reliance on the energy from the utility grid. By providing peak shaving and other ancillary services, microgrids presents as a mechanism to fully utilize the benefits of the DERs and to promote a highly efficient energy delivery and supply system [11]. As one of the most successful commercial applications for microgrids [12], the optimization of CHP systems has drawn a lot of interests in recent years.…”