Renewable Energy Zones Integration in Weak Transmission Networks

Sakib, Sadnan

Renewable Energy Zones Integration in Weak Transmission Networks

Sakib, Sadnan

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Publication Type:: Thesis
Issue Date:: 2026

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Field	Value	Language
dc.contributor.author	Sakib, Sadnan
dc.date.accessioned	2026-10-27T00:49:04Z
dc.date.available	2026-10-27T00:49:04Z
dc.date.issued	2026
dc.identifier.uri	http://hdl.handle.net/10453/197258
dc.description	University of Technology Sydney. Faculty of Engineering and Information Technology.	en_US.UTF-8
dc.description.abstract	The rapid expansion of inverter-based renewable energy within Australia's Renewable Energy Zones (REZs) has intensified long-standing challenges in weak transmission networks, where low inertia, high impedance, and limited fault-clearing capability compromise voltage stability, frequency resilience, and overall system security. As synchronous machines are displaced by photovoltaic, wind, and storage technologies, conventional control and support mechanisms have become insufficient for maintaining reliable operation. Addressing these gaps requires system-level control strategies capable of enhancing stability under high renewable penetration. The first major contribution of this thesis is the development of a cascaded control parameter optimisation framework that strengthens voltage stability and fault-ride-through (FRT) capability in weak-grid REZ environments. This contribution introduces a Dynamic Resilience Metric that quantitatively captures transient behaviour, fault-clearing margins, and post-fault recovery characteristics. Guided by this metric, an enhanced Particle Swarm Optimisation routine simultaneously tunes plant-level, network-level, and converter-level controllers, an approach that surpasses traditional single-layer optimisation. Extensive validation on a simplified Australian 14-Generator Test System demonstrates significant improvements in system stability, including reductions in voltage overshoot to 6-25\% and extended permissible fault-clearing times of 255-270 ms. These results show that coordinated, multi-layer optimisation provides a scalable and systematic means of reinforcing weak renewable-dominated grids. The second major contribution proposes a severity-aware coordinated control framework for Battery Energy Storage Systems (BESS), introducing a disturbance-driven mechanism that adaptively blends grid-following (GFL) and grid-forming (GFM) inverter modes. This strategy ensures efficient current-following during normal conditions while activating robust voltage-forming and frequency support during severe disturbances. Through parametric studies of GFM:GFL penetration ratios, the framework demonstrates monotonic improvements in frequency nadir, RoCoF suppression, and voltage recovery. A comparative evaluation of Droop and Virtual Synchronous Machine (VSM) techniques further clarifies their respective advantages, revealing Droop's superior transient performance and VSM's enhanced damping and black-start capability. This contribution establishes a practical, adaptive pathway for inverter coordination in renewable-rich weak networks. Together, these contributions offer a unified and grid-aligned framework for enhancing the stability, resilience, and renewable hosting capacity of REZ-based weak transmission systems, supporting Australia's transition toward a reliable and sustainable energy future.	en_US.UTF-8
dc.format	Thesis (ME)
dc.language.iso	en_US	en_US.UTF-8
dc.relation	https://opus.lib.uts.edu.au/bitstream/10453/197258/1/thesis.pdf
dc.rights	info:eu-repo/semantics/openAccess
dc.rights	The author owns the copyright in this thesis including all reproduction and reuse rights for the work. The work may not be altered without the permission of the copyright owner. Attribution is essential when quoting or paraphrasing from this thesis.
dc.rights	© 2026 Sadnan Sakib
dc.rights	au.edu.uts.lib/cph
dc.title	Renewable Energy Zones Integration in Weak Transmission Networks	en_US.UTF-8
dc.type	Thesis
utslib.copyright.status	open_access	*

Abstract:

The rapid expansion of inverter-based renewable energy within Australia's Renewable Energy Zones (REZs) has intensified long-standing challenges in weak transmission networks, where low inertia, high impedance, and limited fault-clearing capability compromise voltage stability, frequency resilience, and overall system security. As synchronous machines are displaced by photovoltaic, wind, and storage technologies, conventional control and support mechanisms have become insufficient for maintaining reliable operation. Addressing these gaps requires system-level control strategies capable of enhancing stability under high renewable penetration. The first major contribution of this thesis is the development of a cascaded control parameter optimisation framework that strengthens voltage stability and fault-ride-through (FRT) capability in weak-grid REZ environments. This contribution introduces a Dynamic Resilience Metric that quantitatively captures transient behaviour, fault-clearing margins, and post-fault recovery characteristics. Guided by this metric, an enhanced Particle Swarm Optimisation routine simultaneously tunes plant-level, network-level, and converter-level controllers, an approach that surpasses traditional single-layer optimisation. Extensive validation on a simplified Australian 14-Generator Test System demonstrates significant improvements in system stability, including reductions in voltage overshoot to 6-25\% and extended permissible fault-clearing times of 255-270 ms. These results show that coordinated, multi-layer optimisation provides a scalable and systematic means of reinforcing weak renewable-dominated grids. The second major contribution proposes a severity-aware coordinated control framework for Battery Energy Storage Systems (BESS), introducing a disturbance-driven mechanism that adaptively blends grid-following (GFL) and grid-forming (GFM) inverter modes. This strategy ensures efficient current-following during normal conditions while activating robust voltage-forming and frequency support during severe disturbances. Through parametric studies of GFM:GFL penetration ratios, the framework demonstrates monotonic improvements in frequency nadir, RoCoF suppression, and voltage recovery. A comparative evaluation of Droop and Virtual Synchronous Machine (VSM) techniques further clarifies their respective advantages, revealing Droop's superior transient performance and VSM's enhanced damping and black-start capability. This contribution establishes a practical, adaptive pathway for inverter coordination in renewable-rich weak networks. Together, these contributions offer a unified and grid-aligned framework for enhancing the stability, resilience, and renewable hosting capacity of REZ-based weak transmission systems, supporting Australia's transition toward a reliable and sustainable energy future.

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