Optimal Power Flow in Multiphase Radial Networks with Delta Connections: Preprint

Conference · Mon Nov 27 04:00:00 EST 2017

OSTI ID:1410967

Zhao, Changhong ^[1]; Dall-Anese, Emiliano ^[1]; Low, Steven H. ^[2]

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1. National Renewable Energy Laboratory (NREL), Golden, CO (United States)
2. California Institute of Technology

This paper focuses on multiphase radial distribution networks with mixed wye and delta connections, and proposes a semidefinite relaxation of the AC optimal power flow (OPF) problem. Two multiphase power-flow models are developed to facilitate the integration of delta-connected generation units/loads in the OPF problem. The first model extends traditional branch flow models - and it is referred to as extended branch flow model (EBFM). The second model leverages a linear relationship between per-phase power injections and delta connections, which holds under a balanced voltage approximation (BVA). Based on these models, pertinent OPF problems are formulated and relaxed to semidefinite programs (SDPs). Numerical studies on IEEE test feeders show that SDP relaxations can be solved efficiently by a generic optimization solver. Numerical evidences indicate that solving the resultant SDP under BVA is faster than under EBFM. Moreover, both SDP solutions are numerically exact with respect to voltages and branch flows. It is also shown that the SDP solution under BVA has a small optimality gap, while the BVA model is accurate in the sense that it reflects actual system voltages.

• Research Organization: National Renewable Energy Laboratory (NREL), Golden, CO (United States)
• Sponsoring Organization: USDOE Advanced Research Projects Agency - Energy (ARPA-E)
• DOE Contract Number: AC36-08GO28308
• OSTI ID: 1410967
• Report Number(s): NREL/CP-5D00-67852
• Country of Publication: United States
• Language: English

Related Subjects

24 POWER TRANSMISSION AND DISTRIBUTION
multiphase distribution network
optimal power flow
semidefinite relaxation