Optimal distributed transaction of multiple microgrids in grid-connected and islanded modes considering unit commitment scheme

•A model convexification for multi-directional energy transactions for MMGs in two modes.•A rounding-off procedure with thresholds for out-of-limit problems of generators.•An AOM to solve continuous and binary variables alternately in a distributed manner.•A theoretical convergence proof for AOM wit...

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Published inInternational journal of electrical power & energy systems Vol. 132; p. 107146
Main Authors Wang, Zhuo, Wang, Luhao, Li, Zhengmao, Cheng, Xingong, Li, Qiqiang
Format Journal Article
LanguageEnglish
Published Elsevier Ltd 01.11.2021
Subjects
Distributed optimization
Energy transactions
Multiple microgrids
Rounding-off procedure
Unit commitment
Distributed optimization
Rounding-off procedure
Multiple microgrids
Energy transactions
Unit commitment
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Summary:•A model convexification for multi-directional energy transactions for MMGs in two modes.•A rounding-off procedure with thresholds for out-of-limit problems of generators.•An AOM to solve continuous and binary variables alternately in a distributed manner.•A theoretical convergence proof for AOM with rounding-off procedure. This paper addresses multi-directional energy trading problems (ETPs) for multiple microgrids (MMGs) in grid-connected and islanded modes considering the unit commitment (UC) scheme. Firstly, a mixed integer quadratic programming (MIQP) model is formulated to describe unit commitment problems (UCPs) for each microgrid (MG) and energy transactions among MMGs. Then binary variables from UCPs are relaxed to convert the original non-convex model into a tractable convex one. Furthermore, an alternating optimization method (AOM) composed of alternating direction method of multipliers (ADMM) and MIQP block is proposed to solve continuous and binary variables alternately. Especially, a rounding-off procedure with thresholds is designed to treat out-of-limit problems of generators and smooth the parameter passing between ADMM and MIQP block with corresponding convergence proof. Finally, comprehensive comparisons are conducted to demonstrate the effectiveness of proposed method. Simulation results indicate that AOM can be directly applied to solve ETPs for MMGs in a distributed manner, and thresholds are effective for operators to adjust the operating range of generators flexibly under the condition that ETPs are completely solvable.
ISSN:0142-0615
DOI:10.1016/j.ijepes.2021.107146