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• Conference paper
  Chen Y, Bhattacharjee D, Chaudhuri B, O'Malley M, Qin N, Expethit APet al., 2026,

  Data-Driven Post-Event Analysis with Real-World Oscillation Data from Denmark

  , IEEE Power and Energy Society General Meeting (PESGM) 2026, Publisher: IEEE

  This paper demonstrates how Extended DynamicMode Decomposition (EDMD), grounded in Koopman operator theory, can effectively identify the main contributor(s) to oscillations in power grids. We use PMU data recorded from a real 0.16 Hz oscillation event in Denmark for post-event analysis. To this end, the EDMD algorithm processed only voltage and current phasors from nineteen PMUs at different voltage levels across theDanish grid. In such a blind-test setting with no supplementary system information, EDMD accurately pinpointed the location of the main contributor to the 0.16 Hz oscillation. Energinet later confirmed that this was a 145 MW solar photovoltaic (PV) park with control system issues. Notably, conventional approaches, such as the dissipating energy flow (DEF) method used in the ISO-NE OSLp tool did not correctly identify this plant. This joint validation with Energinet, reinforcing earlier studies using simulated IBR-dominated systems and real PMUdata from ISO-NE, highlights the potential of EDMD-based post-event analysis for identifying major oscillation contributors and enabling targeted SSO mitigation.

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• Conference paper
  Javaid MS, Covarrubias Maureira G, Gupta A, Bhattacharjee D, Gao J, Chaudhuri B, O'Malley Met al., 2026,

  Spatial Characterization of Sub-Synchronous Oscillations Using Black-Box IBR Models

  , IEEE Power and Energy Society General Meeting (PESGM) 2026, Publisher: IEEE

  Power systems with high penetration of inverter-basedresources (IBRs) are prone to sub-synchronous oscillations(SSO). The opaqueness of vendor-specific IBR models limits the ability to predict the severity and the spread of SSO. This paper demonstrates that black-box IBR models estimated through frequency-domain identification techniques, along with dynamic network model can replicate the actual oscillatory behavior. The estimated IBR models are validated against actual IBR modelsin a closed-loop multi-IBR test system through modal analysis by comparing closed-loop eigenvalues, and participation factors. Furthermore, using output-observable right eigenvectors, spatial heatmaps are developed to visualize the spread and severity of dominant SSO modes. The case studies on the 11-bus and 39-bus test systems confirm that even with the estimated IBR models, theregions susceptible to SSO can be identified in IBR-dominated power systems.

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• Journal article
  Gu Y, Chaudhuri B, Green T, Xiaoyao Z, Ramachandran Jet al., 2026,

  Multi-layered defense against oscillations

  , IEEE Power and Energy Magazine, Vol: 24, Pages: 39-48, ISSN: 1540-7977

  Increasing shares of inverter-based resources (IBRs) in power grids are triggering complex dynamic interactions and new stability challenges. A particular challenge for system operators is poorly damped sub-synchronous oscillations (SSO) induced by adverse interaction among IBRs through the network. These oscillations are difficult to foresee, threaten system security and often force grid operators to limit the instantaneous share of IBRs. The Control and Power research group at Imperial College London are working with the Network Operability team in National Energy System Operator (NESO) in the UK to develop a multi-layered defense strategy to identify and mitigate the risk of poorly damped SSO. Starting from advanced IBR control design which is the genesis of the SSO problem, these layers are: 1) an enhanced IBR connection compliance process capture the risk of SSO more comprehensively, 2) new system strength metrices to identify parts of the grid vulnerable to SSO, 3) characterize operating point dependency of IBRs to detect incipient SSO near real-time and 4) post-event root-cause analysis for targeted and effective mitigation of SSO. Success of this research will enable secure grid operation with high fractions of renewables to facilitate net zero transition.

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• Journal article
  Gao J, Chaudhuri B, Astolfi A, 2026,

  An explicit direct method for transient stability analysis of multimachine power systems with nonzero transfer conductances

  , IEEE Transactions on Control Systems Technology, Vol: 34, Pages: 112-122, ISSN: 1063-6536

  We propose an explicit analytical direct method for the transient stability analysis of multimachine power systems with nonzero transfer conductances (TCs). The proposed method addresses two issues. In the first issue, we study the transient stabilization of the entire power system through excitation control design. To this end, a globally well-defined Lyapunov function is constructed, and a locally well-defined dynamic passivity-based control law is proposed. The closed-loop equilibrium is therefore guaranteed to be locally asymptotically stable. In the second issue, we study the transient stability property of post-fault initial states. To this end, an optimization-based approach to calculate the critical level set of the proposed Lyapunov function is proposed. This allows to estimate an explicit region of attraction of the closed-loop equilibrium. Therefore, the transient stability property of a post-fault initial state can be directly assessed. A case study on the IEEE 10-machine 39-bus power system, to demonstrate the performance and effectiveness of the proposed direct method, is presented.

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• Conference paper
  Javaid MS, Chaudhuri B, Teng F, Akhtar Zet al., 2025,

  Impact of inner control in GFM-induced sub-synchronous oscillations

  , 2025 IEEE PES General Meeting, Publisher: IEEE

  n power systems dominated by grid-forming inverters (GFMs), strong grid conditions can lead to sub-synchronous oscillations (SSOs) due to the reduced time-scale separation between GFM control loops and network dynamics, potentially causing instability. Modal analysis reveals that states associated with inner control (comprising current and voltage control loops) and network dynamics are the primary contributors to these oscillatory modes. This paper provides an analytical explanation of adverse interactions between GFM inner control and network dynamics that lead to SSOs. Through damping ratio sensitivity analysis, we establish that increasing the current control closed-loop bandwidth and the voltage control proportional gaincan effectively mitigate these oscillations. The proposed control adjustments also prove effective in larger systems with 100% inverter-based resources penetration, comprising of a mix of both grid-following and grid-forming inverters.

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• Conference paper
  Javaid M, Chaudhuri B, Teng F, Akhtar Zet al., 2025,

  A novel tuning method of grid-forming inverter voltage control

  , IEEE PowerTech 2025, Publisher: IEEE

  Grid-forming inverters (GFMs) may experience instabilityin strong grids, often resulting from voltage controlinterference, particularly when multiple voltage sources are electrically close. This issue is further exacerbated when control gains are obtained under avoidable assumptions. A temporary solution is to retune control gain, yet it yields suboptimal performance. To address this, we propose a novel tuning technique for GFM control that employs a concurrent design approach for d and q axes voltage control. The proposed method also incorporates the dynamics of an equivalent grid model in the design process. The required design specifications are translated into weighting functions, formulating the H∞ minimization problem for optimal tuning. The proposed tuning method is compared against direct synthesis and symmetrical optimum methods. The comparison reveals the advantages of the proposed method in mitigating the impact of grid strength. Their performance is evaluated on 9-bus and 11-bus test systems. It is shown that the proposed approach achieves higher control bandwidth and improved stability margins compared to conventional designs.

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• Journal article
  Ochoa T, Serpell C, Valle C, Gil Eet al., 2025,

  Enhancing short-term probabilistic load forecasting and scenario generation with tailored kernel functions in mixture density networks

  , EXPERT SYSTEMS WITH APPLICATIONS, Vol: 284, ISSN: 0957-4174
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  • Citations: 3
• Journal article
  Javaid MS, Chaudhuri B, Teng F, Akhtar Zet al., 2025,

  EMT−RMS modeling trade-off for IBR-driven sub-synchronous oscillations

  , IEEE Transactions on Power Systems, ISSN: 0885-8950

  Low-frequency electromechanical oscillations (<2Hz) are time-separated from faster network dynamics, allowing network dynamics to be safely neglected in positive-sequence RMS (RMS+) studies. However, with increasing shares of inverter-based resources (IBRs), sub-synchronous oscillations (SSOs) occur at higher frequencies (>5 Hz) within the electromagnetic timescales. The shift challenges using RMS+ tools for planning IBR-dominated grids, as the time-scale separation is no longer as distinct as in synchronous machine-based systems. This paper demonstrates that relying on RMS+ studies in high-IBRscenarios can lead to erroneous conclusions about SSO, including a false assurance of stability. We explain how the interaction between IBR control and network dynamics affect the damping of SSO. This highlights the need for EMT-dq with network dynamics in a synchronously rotating reference frame as a middle ground between EMT-abc (point-on-wave) and RMS+ for studying IBR-drivenSSO. EMT-dq is computationally simpler than EMTabcand allows frequency-domain analysis for deeper insightand effective SSO mitigation. This emphasizes the necessity of established (rather than bespoke) EMT-dq tools to quickly screen SSO-prone scenarios for detailed investigation in EMT-abc.

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• Conference paper
  Tekcan E, Spyrou E, 2025,

  BMViewGB: an interactive web based tool for visualising the operations of the balancing mechanism in Great Britain

  , 24th Wind & Solar Integration Workshop, Publisher: IET, ISSN: 2732-4494

  The Balancing Mechanism (BM) is the main tool for keeping electricity supply and demand balanced in Great Britain, while respecting network constraints. Between April 2022 and March 2025, its costs were £2–3 billion per year, prompting participants to call for more efficient dispatch and greater transparency. To help meet these needs, the article presents BMViewGB, an open-source, map-based visualisation tool that displays the spatial distribution of BM costs and volumes. The straightforward map layout is designed for users with varied professional backgrounds and can also act as a foundation for further research, such as the development of digital simulators of the Balancing Mechanism.

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• Journal article
  Maity A, Brahma D, Senroy N, 2025,

  Identification of RoCoF sensitive areas of power system based on its controlling factors

  , ELECTRIC POWER SYSTEMS RESEARCH, Vol: 244, ISSN: 0378-7796
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