Thesis

Enhanced frequency control in future low-inertia power systems based on digital twins of distributed energy resources

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Awarding institution
  • University of Strathclyde
Date of award
  • 2025
Thesis identifier
  • T17489
Person Identifier (Local)
  • 202061886
Qualification Level
Qualification Name
Department, School or Faculty
Abstract
  • The increasing penetration of converter-interfaced renewable energy sources has fundamentally transformed modern power systems, which results in a dramatic reduction in system inertia and creates urgent challenges for frequency control. Distributed energy resources (DERs), which constitute a major part of emerging power generation, are expected to play a crucial role in supporting frequency regulation in future low-inertia systems. However, their effectiveness remains constrained due to limited visibility, diverse response capabilities, and communication challenges. This thesis investigates the use of Digital Twins (DTs) as an enabling technology to address these issues through providing real-time monitoring and predictive capabilities for DERs, thereby enabling new frequency service dispatch and control schemes for future power systems. Three DT modelling approaches, i.e. physics-based, system identification-based, and data-driven, are developed and validated, each providing distinct advantages for dynamic representation of DER behaviour. The proposed methodologies consider the model fidelity and efficiency for different applications, and the developed DTs represent the first of their kind to enable real-time representation of DER frequency and active power responses. A method for determining the minimum reporting rate of input signals is also introduced, which ensures accurate DT behaviour under practical operating conditions. In addition, a novel strategy for handling communication delays and jitter is presented, based on sample reordering and timestamp-based linear reconstruction, which significantly improves the robustness of DT-based applications. Case studies are conducted using a hardware-in-the-loop platform, which is specifically designed and established to meet the unique requirements of DT applications. The test results confirm that DTs can accurately replicate DER dynamics. A DT-based DER dispatch framework is developed based on these foundations. The CNN-based DTs within aggregators enables system operators to assess the aggregated response of DERs, and identify gap between expected and actual responses in real time. The iterative what-if scenario analysis is performed on the framework and initiate redispatch processes to correct shortfalls. Case studies demonstrate that the proposed dispatch framework reduces the risk of under-provision and enhances system resilience under frequency events. A DT-based coordinated control scheme is proposed to further enhance the frequency control capability of DERs. Both centralised (cloud-hosted) and distributed (edgehosted) architectures are investigated to address different system and communication requirements. The DTs enable conventional coordinated control of DERs by avoiding communication delay in DERs’ dynamics transmission. A series of case studies validate the effectiveness of the approach, showing improvements over conventional control in terms of speed, overshoot, and accuracy of active power responses. The grid frequency is more effectively supported by coordinated DERs, result in an increased frequency nadir during potential events.
Advisor / supervisor
  • Hong, Qiteng
Resource Type
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