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Conference paperBrahma D, O'Malley M, Chaudhuri B, et al., 2025,
A deeper perspective on IBR-driven oscillations
, 23rd Wind & Solar Integration Workshop (WIW 2024), Publisher: The Institution of Engineering and Technology (IET), Pages: 1130-1137, ISSN: 2732-4494Inverter-based resources (IBRs) are pivotal in modern power systems to meet the net-zero carbon targets. The rapid integration of IBRs such as solar photovoltaics, wind turbines, and battery storage has introduced complex dynamic behaviours that challenge conventional power system stability paradigms. Unlike traditional synchronous generators, which are governed by standardized, physics-based models, IBRs are control-defined and feature vendor-specific models that operate across multiple overlapping time scales. This results in unique dynamic interactions in IBR-dominated grids with multiple causalities, giving rise to oscillatory phenomena not previously encountered. This paper provides a review of IBR-driven oscillations, emphasizing on their classification and current research efforts in oscillation tracing and mitigation. Two classification framework based on time-scale separation and causality, are explored to categorize IBR-induced oscillations, highlighting the challenges in the categorization process. The critical role of data, tools and methods for tracing oscillations is discussed, and current mitigation measures are outlined in the context of IBR-dominated system. Additionally, some open research questions related to the evolving landscape of IBR-induced oscillatory phenomena are discussed.
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Journal articleSpyrou E, Zhang Q, Hytowitz R, et al., 2025,
Flexibility options: a proposed product for managing imbalance risk
, IEEE Transactions on Energy Markets, Policy and Regulation, ISSN: 2771-9626The presence of variable renewable energy resources with uncertain outputs in day-ahead electricity markets results in additional balancing needs in real-time. Addressing those needs cost-effectively and reliably within a competitive market with unbundled products is challenging as both the demand for and the availability of flexibility depends on day-ahead energy schedules. Existing approaches for reserve procurement usually rely either on oversimplified demand curves that do not consider how system conditions that particular day affect the value of flexibility, or on bilateral trading of hedging instruments that are not co-optimized with day-ahead schedules. This article proposes a new product, ‘Flexibility Options’, to address these two limitations. The demand for this product is endogenously determined in the day-ahead market and it is met cost-effectively by considering real-time supply curves for product providers, which are co-optimized with the energy supply. As we illustrate with numerical examples and mathematical analysis, the product addresses the hedging needs of participants with imbalances cost-effectively, provides a less intermittent revenue stream for participants with flexible outputs, promotes value-driven pricing of flexibility, and ensures that the system operator is revenue-neutral. This article provides a comprehensive design that can be further tested and applied in large-scale systems.
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Book chapterBialek J, O’Malley M, 2025,
The grid of the future and what regulators need to know about it
, Handbook on Electricity Regulation, Pages: 269-283The following features have characterised traditional grids: (i) they were powered by large thermal/hydro/nuclear power stations whose output was fully controllable and therefore predictable, (ii) their technical characteristics were determined by the physics of synchronous machines used to convert mechanical/thermal energy into AC electricity. However, the combined drivers of decarbonisation and reduced costs of variable renewable resources (VRE), such as wind and solar photovoltaics stations, led to increased penetration of VREs with the following consequences: (i) the output of VRE plants is no longer controllable or fully predictable due to vagaries of weather (ii) the system technical characteristics are determined by control algorithms of inverters which connect VRE plants to the grid. This chapter covers the challenges the inverter-based grids pose for power system operation and planning. In particular we cover the resources adequacy challenge and the services challenge (synchronisation, frequency control, voltage control, damping, protection, blackstart and restoration).
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Journal articleLiang X, Li Q, Ilic M, et al., 2025,
Guest Editorial: Convergence of Data-Driven and Physics-Based Approaches in Power System Analysis, Optimization, and Control
, IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS, Vol: 61, Pages: 2349-2352, ISSN: 0093-9994 -
Journal articleChu Z, Teng F, 2025,
Coordinated Planning for Stability Enhancement in High IBR-Penetrated Systems
, IEEE TRANSACTIONS ON SUSTAINABLE ENERGY, Vol: 16, Pages: 700-715, ISSN: 1949-3029 -
Journal articleChu Z, Teng F, 2025,
Managing the Uncertainty in System Dynamics Through Distributionally Robust Stability-Constrained Optimization
, IEEE TRANSACTIONS ON POWER SYSTEMS, Vol: 40, Pages: 449-462, ISSN: 0885-8950- Cite
- Citations: 2
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Journal articleSpyrou E, Hobbs B, Chattopadhyay D, et al., 2024,
How to assess uncertainty-aware frameworks for power system planning?
, IEEE Transactions on Energy Markets, Policy and Regulation, Vol: 2, Pages: 436-448, ISSN: 2771-9626Computational advances along with the profound impact of uncertainty on power system investments have motivated the creation of power system planning frameworks that handle long-run uncertainty, large number of alternative plans, and multiple objectives. Planning agencies seek guidance to assess such frameworks. This article addresses this need in two ways. First, we augment previously proposed criteria for assessing planning frameworks by including new criteria such as stakeholder acceptance to make the assessments more comprehensive, while enhancing the practical applicability of assessment criteria by offering criterion-specific themes and questions. Second, using the proposed criteria, we compare two widely used but fundamentally distinct frameworks: an ‘agree-on-plans’ framework, Robust Decision Making (RDM), and an ‘agree-on-assumptions’ framework, centered around Stochastic Programming (SP). By comparing for the first time head-to-head the two distinct frameworks for an electricity supply planning problem under uncertainties in Bangladesh, we conclude that RDM relies on a large number of simulations to provide ample information to decision makers and stakeholders, and to facilitate updating of subjective inputs. In contrast, SP is a highly dimensional optimization problem that identifies plans with relatively good probability-weighted performance in a single step, but even with computational advances remains subject to the curse of dimensionality.
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Journal articleO'Malley M, Holttinen H, Cutululis N, et al., 2024,
Grand challenges of wind energy science - meeting the needs and services of the power system
, Wind Energy Science, Vol: 9, Pages: 2087-2112, ISSN: 2366-7443The share of wind power in power systems is increasing dramatically, and this is happening in parallel with increased penetration of solar photovoltaics, storage, other inverter-based technologies, and electrification of other sectors. Recognising the fundamental objective of power systems, maintaining supply–demand balance reliably at the lowest cost, and integrating all these technologies are significant research challenges that are driving radical changes to planning and operations of power systems globally. In this changing environment, wind power can maximise its long-term value to the power system by balancing the needs it imposes on the power system with its contribution to addressing these needs with services. A needs and services paradigm is adopted here to highlight these research challenges, which should also be guided by a balanced approach, concentrating on its advantages over competitors. The research challenges within the wind technology itself are many and varied, with control and coordination internally being a focal point in parallel with a strong recommendation for a holistic approach targeted at where wind has an advantage over its competitors and in coordination with research into other technologies such as storage, power electronics, and power systems.
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Conference paperThakar S, Ramasubramanian D, Matevosyan J, et al., 2024,
System services from inverter based resources for reliable operation
, 2024 IEEE Power & Energy Society General Meeting (PESGM), Publisher: IEEE, Pages: 1-5With the increasing penetration of inverter based resources (IBRs) in present and future power systems, it is important to consider the different grid services needed from/provided by IBRs. To ensure network stability after a contingency such as trip of a synchronous generator or a fault, a grid may require services (for example, fast voltage control) from various IBRs. New IBRs to be installed with future capabilities (inherent blackstart capability) are often seen as a potential source for such services. However, the capability of many existing IBRs today are underutilized and if the capability from existing IBRs is utilized efficiently, it could greatly improve the network performance and reduce services needed from the future IBRs. This paper provides few illustrative examples detailing some of the services that may be needed by an IBR-dominated grid and the impact of asking these services from future IBRs and/or supplementing with services from existing IBRs.
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Journal articleChu Z, Wu J, Teng F, 2024,
Pricing of short circuit current in high IBR-penetrated system
, ELECTRIC POWER SYSTEMS RESEARCH, Vol: 235, ISSN: 0378-7796
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Publications from colleagues on EPICS-UK outside of Imperial: