TK
T.R. Karmokar
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1
Increasing wind farm capacity via overplanting enhances energy production but risks accelerating cable aging if transmission capacity is poorly managed. Consequently, resilient Dynamic Cable Rating (DCR) prediction-defined as the ability to maintain stability under data quality degradation and operational shifts-is crucial for reliable operation. However, achieving this is challenged by limited datasets, missing data, and complex spatio-temporal correlations. To address these issues, a resilient DCR prediction and thermal estimation framework is developed. First, a Conditional Generative Adversarial Network (CGAN) is applied to synthetically augment limited datasets, effectively resolving the load data imbalance. Second, a Spatio-Temporal Graph Attention Residual Shrinkage Network (STGARSN) is proposed. This model integrates an extended Long Short-Term Memory (LSTM) network with Temporal Convolutional Networks (TCN) and a graph attention mechanism to capture complex correlations. Crucially, it incorporates a residual shrinkage module to filter noise and outliers, thereby ensuring model resilience. Finally, to optimize economic performance while minimizing cable aging, a comparative analysis of various overplanting strategies is conducted. Experiments on real cable temperature measurements demonstrate the superior resilience of the proposed model, maintaining high accuracy not only across different forecasting horizons but also under conditions of missing data and sensor noise. The proposed framework accurately predicts DCR and supports long-term offshore wind farm operations through improved economic and technical decision-making.
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Increasing wind farm capacity via overplanting enhances energy production but risks accelerating cable aging if transmission capacity is poorly managed. Consequently, resilient Dynamic Cable Rating (DCR) prediction-defined as the ability to maintain stability under data quality degradation and operational shifts-is crucial for reliable operation. However, achieving this is challenged by limited datasets, missing data, and complex spatio-temporal correlations. To address these issues, a resilient DCR prediction and thermal estimation framework is developed. First, a Conditional Generative Adversarial Network (CGAN) is applied to synthetically augment limited datasets, effectively resolving the load data imbalance. Second, a Spatio-Temporal Graph Attention Residual Shrinkage Network (STGARSN) is proposed. This model integrates an extended Long Short-Term Memory (LSTM) network with Temporal Convolutional Networks (TCN) and a graph attention mechanism to capture complex correlations. Crucially, it incorporates a residual shrinkage module to filter noise and outliers, thereby ensuring model resilience. Finally, to optimize economic performance while minimizing cable aging, a comparative analysis of various overplanting strategies is conducted. Experiments on real cable temperature measurements demonstrate the superior resilience of the proposed model, maintaining high accuracy not only across different forecasting horizons but also under conditions of missing data and sensor noise. The proposed framework accurately predicts DCR and supports long-term offshore wind farm operations through improved economic and technical decision-making.
Transient Overvoltages in Onshore HVDC Cable Joints
Surge Reflections and the Influence of Grounding Configurations
This study examines transient overvoltage phenomena in 525 kV high-voltage direct current (HVDC) onshore cable systems, with particular emphasis on the influence of grounding configurations in two joint types: straight-through and screen-separated. Transient overvoltages arising from wave propagation and reflections are analysed, highlighting the impact of joint types, bonding cable configurations (coaxial vs. noncoaxial) and bonding cable length on the resulting overvoltage magnitudes. The necessity of modelling screen-to-earth representations of sectionalised cables at grounded joint locations in the vicinity of faults is emphasised, whereas simplified representations of ungrounded and grounded straight-through joints are identified as sufficient for system-level simulations. To address the computational challenges of detailed electromagnetic transient simulations, a stand-alone simplified circuit is proposed to analyse grounded joint transients and to mitigate errors caused by insufficient time-step resolution. The results provide practical insights for insulation coordination, supporting the reliable integration of HVDC technology into long-distance cable-based transmission networks while enhancing system resilience.
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This study examines transient overvoltage phenomena in 525 kV high-voltage direct current (HVDC) onshore cable systems, with particular emphasis on the influence of grounding configurations in two joint types: straight-through and screen-separated. Transient overvoltages arising from wave propagation and reflections are analysed, highlighting the impact of joint types, bonding cable configurations (coaxial vs. noncoaxial) and bonding cable length on the resulting overvoltage magnitudes. The necessity of modelling screen-to-earth representations of sectionalised cables at grounded joint locations in the vicinity of faults is emphasised, whereas simplified representations of ungrounded and grounded straight-through joints are identified as sufficient for system-level simulations. To address the computational challenges of detailed electromagnetic transient simulations, a stand-alone simplified circuit is proposed to analyse grounded joint transients and to mitigate errors caused by insufficient time-step resolution. The results provide practical insights for insulation coordination, supporting the reliable integration of HVDC technology into long-distance cable-based transmission networks while enhancing system resilience.
HVDC cable systems are vital for long-distance power transmission, especially for offshore wind energy. The point-to-point HVDC transmission links are already in use. For enhanced system reliability, interconnected DC network with fault separation devices like DC circuit breakers are envisaged. This requires the evaluation of the interface between DC cables and circuit breakers for different contingency scenarios. Electromagnetic transient simulations are commonly employed for HVDC network analysis. This paper proposes a practice-based approach to accurately model cable systems, which are crucial for reliable HVDC network analysis. It emphasizes considering real-world implications of cable manufacturing and installation conditions. By enhancing existing knowledge of cable parameter determination, this study proposes practical models using EMT simulations. The aim is to provide engineers with a systematic method to convert DC cable data into EMT-compatible parameters, facilitating representative modelling for thorough HVDC network performance assessment. This is vital for de ning speci cations of complex HVDC systems, particularly multi-terminal networks.
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HVDC cable systems are vital for long-distance power transmission, especially for offshore wind energy. The point-to-point HVDC transmission links are already in use. For enhanced system reliability, interconnected DC network with fault separation devices like DC circuit breakers are envisaged. This requires the evaluation of the interface between DC cables and circuit breakers for different contingency scenarios. Electromagnetic transient simulations are commonly employed for HVDC network analysis. This paper proposes a practice-based approach to accurately model cable systems, which are crucial for reliable HVDC network analysis. It emphasizes considering real-world implications of cable manufacturing and installation conditions. By enhancing existing knowledge of cable parameter determination, this study proposes practical models using EMT simulations. The aim is to provide engineers with a systematic method to convert DC cable data into EMT-compatible parameters, facilitating representative modelling for thorough HVDC network performance assessment. This is vital for de ning speci cations of complex HVDC systems, particularly multi-terminal networks.
Multiterminal (MT) HVDC grids require dependable DC circuit breaker (DCCB) operation. Electromagnetic-transient (EMT) simulations show that DCCB interruption produces relatively slow-front transient overvoltage (TrOV) whose crest- and duration-stresses on HVDC cable systems are not fully exercised by today’s standard lightning (ULI,std) and switching (USI,std) impulse voltage tests. This paper quantifies these stresses and proposes a parameterized hybrid impulse (Uhyb) superimposed on DC that envelopes SI-class wavefronts and LTrOV-class durations using SI-referenced exceedance metrics (S1, Sn) and t90/t70/t50 checks. A unified type test sequence is outlined, preserving IEC measurement tolerances and existing qualifications, and enabling robust insulation coordination for MT-HVDC grids.
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Multiterminal (MT) HVDC grids require dependable DC circuit breaker (DCCB) operation. Electromagnetic-transient (EMT) simulations show that DCCB interruption produces relatively slow-front transient overvoltage (TrOV) whose crest- and duration-stresses on HVDC cable systems are not fully exercised by today’s standard lightning (ULI,std) and switching (USI,std) impulse voltage tests. This paper quantifies these stresses and proposes a parameterized hybrid impulse (Uhyb) superimposed on DC that envelopes SI-class wavefronts and LTrOV-class durations using SI-referenced exceedance metrics (S1, Sn) and t90/t70/t50 checks. A unified type test sequence is outlined, preserving IEC measurement tolerances and existing qualifications, and enabling robust insulation coordination for MT-HVDC grids.
This paper presents an analytical framework for understanding DC fault current interruption dynamics using fundamental electrical circuit principles. It examines the interruption mechanisms of a DC circuit breaker with a detailed HVDC cable model through Electromagnetic Transient (EMT) simulations. The research integrates analytical and numerical simulation approaches during fault conditions to assess varying parameters for the impact of DC fault current interruption on estimating the resulting cable stresses. This research aims to advance HVDC transmission technology by providing a com-prehensive understanding of DC fault current interruption dynamics of cable-based networks.
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This paper presents an analytical framework for understanding DC fault current interruption dynamics using fundamental electrical circuit principles. It examines the interruption mechanisms of a DC circuit breaker with a detailed HVDC cable model through Electromagnetic Transient (EMT) simulations. The research integrates analytical and numerical simulation approaches during fault conditions to assess varying parameters for the impact of DC fault current interruption on estimating the resulting cable stresses. This research aims to advance HVDC transmission technology by providing a com-prehensive understanding of DC fault current interruption dynamics of cable-based networks.
Real-time simulations have become a crucial tool for life cycle studies of VSC-based HVDC systems. This paper introduces real-time Multi-Terminal HVDC (MTDC) power [1] system network models with real-time wind pro le feedback. It addresses the shortcomings of existing benchmark network models and lls the modeling gaps. ® RSCAD/RTDS environment represents the real-time modeling techniques for studying the life cycle of Bipolar Metallic Return con guration of HVDC systems. This paper evaluates the performance of the proposed network model using unscheduled events, startup, and black start events. Future studies can be conducted using the proposed network models by mimicking the actual performance of cable-based DC grids while considering the computational insights from this paper. The ndings of this paper shall enable the identi cation of various stress points that can be utilized to specify technical requirements for component design and AC/DC protection studies concerning startup and black start sequence.
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Real-time simulations have become a crucial tool for life cycle studies of VSC-based HVDC systems. This paper introduces real-time Multi-Terminal HVDC (MTDC) power [1] system network models with real-time wind pro le feedback. It addresses the shortcomings of existing benchmark network models and lls the modeling gaps. ® RSCAD/RTDS environment represents the real-time modeling techniques for studying the life cycle of Bipolar Metallic Return con guration of HVDC systems. This paper evaluates the performance of the proposed network model using unscheduled events, startup, and black start events. Future studies can be conducted using the proposed network models by mimicking the actual performance of cable-based DC grids while considering the computational insights from this paper. The ndings of this paper shall enable the identi cation of various stress points that can be utilized to specify technical requirements for component design and AC/DC protection studies concerning startup and black start sequence.