Transmission switching is widely used in the electric power industry for both preventive and corrective purposes. Optimal transmission switching (OTS) problems are usually formulated based on optimal power flow (OPF) problems. OTS problems are originally nonlinear optimization problems with binary integer variables indicating whether a transmission line is in or out of service, however, they can be linearized into mixed-integer linear programs (MILP) through the big-M method. In such big-M-based MILP problems, the value of M can significantly affect their computational efficiency. This paper proposes a method to find the optimal big-M values for OTS problems and studies the impact of big-M values on the computational efficiency of OTS problems. The model was implemented on a modified RTS-96 test system, and the results show that the proposed model can effectively reduce the computational time by finding an optimal big-M value which ensures optimal switching solutions while maintaining numerical stability.
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Machine Learning-Accelerated Method for Real-Time Optimization of Micro Energy-Water-Hydrogen Nexus
This paper explores the micro Energy-Water-Hydrogen (m-EWH) nexus, an engineering system designed to reduce carbon emissions in the power sector. The m-EWH nexus leverages renewable energy sources (RES) to produce hydrogen via electrolysis, which is then combined with carbon captured from fossil fuel power plants to mitigate emissions. To address the uncertainty challenges posed by RES, this paper proposes a real-time decision-making framework for the m-EWH nexus, which requires the rapid solution of large-scale mixed-integer convex programming (MICP) problems. To this end, we develop a machine learning-accelerated solution method for real-time optimization (MARO), comprising three key modules: (1) an active constraint and integer variable prediction module that rapidly solves MICP problems using historical optimization data; (2) an optimal strategy selection module based on feasibility ranking to ensure solution feasibility; and (3) a feature space extension and refinement module to improve solution accuracy by generating new features and refining existing ones. The effectiveness of the MARO method is validated through two case studies of the m-EWH nexus, demonstrating its capability to swiftly and accurately solve MICP problems for this complex system.
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- Award ID(s):
- 2124849
- PAR ID:
- 10562970
- Publisher / Repository:
- IEEE
- Date Published:
- Journal Name:
- IEEE Transactions on Sustainable Energy
- ISSN:
- 1949-3029
- Page Range / eLocation ID:
- 1 to 11
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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