Optimization and control of voltage in active distribution networks

Alshehri, Mohammed (2026) Optimization and control of voltage in active distribution networks. PhD thesis, University of Glasgow.

Abstract

The global transition towards decarbonized and decentralized energy systems is driving the rapid integration of Distributed Energy Resources (DERs), such as solar photovoltaic (PV) systems and wind turbines, into electricity distribution networks. This evolution transforms traditionally passive networks into Active Distribution Networks (ADNs), characterized by bidirectional power flows, voltage fluctuations, and increased operational complexity. Voltage regulation emerges as a paramount challenge in this context, as the stochastic nature of renewable generation can lead to voltage violations, elevated power losses, and significant phase unbalance, particularly in inherently unbalanced three-phase low-voltage networks. While traditional devices like On-Load Tap Changers (OLTCs) provide a foundational means of voltage control, they lack the speed and flexibility to manage the spatial and temporal variations introduced by high DER penetration.

This thesis addresses these challenges by proposing and validating a series of integrated optimization frameworks that leverage the capabilities of power electronic-based Soft Open Points (SOPs) and Energy Storage Systems (ESS). The core of this research lies in the coordinated operation of these advanced technologies with traditional infrastructure to enhance the technical and economic performance of ADNs. A convex semidefinite programming (SDP) approach is used to optimize voltage profiles, reduce power losses, and improve phase balancing. Furthermore, the work introduces an economic model that includes grid purchase cost, battery degradation, and PV curtailment to ensure financially efficient operation. To tackle large-scale and time-coupled optimization, accelerated variants of the Alternating Direction Method of Multipliers (ADMM) are applied. Case studies on IEEE 13-bus and 123-bus systems validate the proposed methods. The results demonstrate the effectiveness of the coordinated operation of OLTC and SOP-ES in reducing losses, enhancing voltage quality, and minimizing economic cost.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Additional Information: Supported by funding from the Royal Commission for Jubail and Yanbu (RCJY), Saudi Arabia.
• Subjects: T Technology > T Technology (General); T Technology > TA Engineering (General). Civil engineering (General)
• Colleges/Schools: College of Science and Engineering > School of Engineering
• Funder's Name: Royal Commission for Jubail and Yanbu (RCJY), Saudi Arabia
• Supervisor's Name: Yang, Professor Jin
• Date of Award: 2026
• Depositing User: Theses Team
• Unique ID: glathesis:2026-85796
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 06 Mar 2026 16:32
• Last Modified: 06 Mar 2026 16:33
• Thesis DOI: 10.5525/gla.thesis.85796
• URI: https://theses.gla.ac.uk/id/eprint/85796

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