Observer based pitch control for load mitigation and power regulation of floating offshore wind turbines Breiffni Fitzgerald, Saptarshi Sarkar Journal of Physics Conference Series, 2024 Most commercial wind turbines use proportional-integral (PI) collective blade-pitch control to regulate rotor speed in the above-rated wind speed regime. A significant drawback of this type of controller is that it assumes that the blades have identical structural properties and are subject to similar aerodynamic loads, which is seldom the case. Also, these controllers are designed to regulate the rotor speed and are not designed for structural vibration/load reduction. However, it is well known that blade pitch control can reduce structural loads on wind turbines. This opens up the possibility of designing controllers that use existing actuators and sensors like the blade pitch actuators to reduce structural loads/vibrations while maintaining the required rotor speed. Recent studies have investigated individual blade pitch control (IPC) to address these shortcomings. However, the vast majority of studies published in the literature depend on the availability of state measurement. Although sensors are commonly placed on all wind turbines, and some information is readily available, the measurement required by the typical state-feedback controllers is usually not available. Displacements and velocities of the blade, the tower and the floating platform are difficult to measure. This paper develops an observer-based individual blade pitch controller for load mitigation and power regulation of floating offshore wind turbines. We propose to use a Kalman filter to estimate the state from the accelerometer and strain gauge measurement for use in the state-feedback controller. The state-feedback controller was proposed previously by the authors that showed excellent performance. This paper extends the capability of the state-feedback controller by designing an observer (Kalman filter) to estimate the state from limited measurements. The proposed observer based controller is compared against a baseline proportional integral collective blade pitch controller and full state-feedback controllers to evaluate its performance. Numerical results show that the proposed output feedback controller offers performance improvements over the baseline controller, similar to the full state-feedback controller.
Optimizing Wind Farm Efficiency through Active Yaw Control: A Neural Network-Aided Game Theory Approach H Abedi, S Sarkar, A Wickström Journal of Physics Conference Series, 2024 This research investigates the potential of a game-theoretic-based Active Yaw Control (AYC) strategy to enhance power generation in wind farms. The proposed AYC strategy in this study replaces traditional look-up tables with a trained Artificial Neural Network (ANN) that determines the optimal yaw misalignment for turbines under time-varying atmospheric conditions. The study examines a hypothetical 3x2 rectangular arrangement of NREL 5-MW wind turbines. The FAST.Farm simulation tool, utilizing the dynamic wake meandering (DWM) model, is employed to assess both the power performance and structural load on the wind turbines. When tested with two different inflow directions and ambient turbulence (10%), the AYC strategy demonstrated a maximum increase in total power output of 2.6%, although it affected individual turbines differently. It also exhibits an increase in some structural loads, such as tower-top torque, while some components experience a slight reduction in load. The results underscore the effectiveness of the ANN-guided game-theoretic algorithm in improving wind farm power generation by mitigating the negative impact of wake interference, offering a scalable and efficient method for optimizing large-scale wind farm. However, it is essential to evaluate the overall impact of AYC on wind farm efficiency in terms of both Annual Energy Production (AEP) and structural loading under various atmospheric conditions.
Mitigation of transient torque reversals in indirect drive wind turbine drivetrains Saptarshi Sarkar, Håkan Johansson, Viktor Berbyuk Wind Energy, 2023 Bearing failure in wind turbine gearboxes is one of the significant sources of downtime. While it is well‐known that bearing failures cause the largest downtime, the failure cause(s) is often elusive. The bearings are designed to satisfy their rolling contact fatigue (RCF) life. However, they often undergo sudden and rapid failure within a few years of operation. It is well‐known that these premature failures are attributed to surface damages such as white surface flaking (WSF), white etching cracks (WECs) and axial cracks. In that regard, transient torque reversals (TTRs) in the drivetrain have emerged as one of the primary triggers of surface damage, as explained in this paper. The risk associated with TTRs motivates the need to mitigate TTRs arising in the drivetrain due to various transient events. This paper investigates three TTR mitigation methods. First, two existing devices, namely, the torsional tuned mass damper and the asymmetric torque limiter, are studied to demonstrate their TTR mitigation capabilities. Then, a novel idea of open‐loop high‐speed shaft mechanical brake control is proposed. The results presented here show that while the torsional tuned mass damper and the asymmetric torque limiter can improve the torsional vibration characteristics of the drivetrain, they cannot mitigate TTRs in terms of eliminating the bearing slip risk associated with TTRs. However, the novel approach proposed here can mitigate TTRs both in terms of improving the torque characteristic in the high‐speed shaft and reducing the risk of bearing slip by actuating the high‐speed shaft brake at the onset of the transient event. Furthermore, the control method is capable of mitigating TTRs with the mechanical limitations of a pneumatic actuator in terms of bandwidth and initial dead time applied to it. This novel approach allows the wind turbines to protect the gearbox bearings from TTRs using the existing hardware on the turbine.
Transient torque reversals in indirect drive wind turbines Saptarshi Sarkar, Håkan Johansson, Viktor Berbyuk Wind Energy, 2023 The adverse effect of transient torque reversals (TTRs) on wind turbine gearboxes can be severe due to their magnitude and rapid occurrence compared with other equipment. The primary damage is caused to the bearings as the bearing loaded zone rapidly changes its direction. Other components are also affected by TTRs (such as gear tooth); however, its impact on bearings is the largest. While the occurrence and severity of TTRs are acknowledged in the industry, there is a lack of academic literature on their initiation, propagation and the associated risk of damage. Furthermore, in the wide range of operation modes of a wind turbine, it is not known which modes can lead to TTRs. Further, the interdependence of TTRs on environmental loading like the wind is also not reported. This paper aims to address these unknowns by expanding on the understanding of TTRs using a high‐fidelity numerical model of an indirect drive wind turbine with a doubly fed induction generator (DFIG). To this end, a multibody model of the drivetrain is developed in SIMPACK. The model of the drivetrain is explicitly coupled to state‐of‐the‐art wind turbine simulator OpenFAST and a grid‐connected DFIG developed in MATLAB®'s Simulink® allowing a coupled analysis of the electromechanical system. A metric termed slip risk duration is proposed in this paper to quantify the risk associated with the TTRs. The paper first investigates a wide range of IEC design load cases to uncover which load cases can lead to TTRs. It was found that emergency stops and symmetric grid voltage drops can lead to TTRs. Next, the dependence of the TTRs on inflow wind parameters is investigated using a sensitivity analysis. It was found that the instantaneous wind speed at the onset of the grid fault or emergency shutdown was the most influential factor in the slip risk duration. The investigation enables the designer to predict the occurrence of TTRs and quantify the associated risk of damage. The paper concludes with recommendations for utility‐scale wind turbines and directions for future research.
Rotor effective wind field estimation and multi-body dynamic characterization of a 45 kW horizontal axis wind turbine D Panda, A Chakraborty, S Sarkar, H Johansson Renewable Energy, 124343 , 2025 2025 Citations: 1
Observer based pitch control for load mitigation and power regulation of floating offshore wind turbines B Fitzgerald, S Sarkar Journal of Physics: Conference Series 2647 (3), 032003 , 2024 2024 Citations: 9
Optimizing wind farm efficiency through active yaw control: a neural network-aided game theory approach H Abedi, S Sarkar, A Wickström Journal of Physics: Conference Series 2767 (9), 092020 , 2024 2024 Citations: 2
Design of tuned mass damper fluid inerter for wind-induced vibration control of a tall building S Sarkar, B Fitzgerald Journal of Structural Engineering 150 (3), 04023242 , 2024 2024 Citations: 18
and power regulation of floating offshore wind-Normal mode approach to modelling of feedback stabilization of the resistive wall turbines mode MS Chu, MS Chance, AH Glasser et al. ZX Ming, C Ju-Fang, P Jian-Hua, B Fitzgerald, S Sarkar Journal of Physics: Conference Series 2647, 032003 , 2024 2024
Mitigation of transient torque reversals in indirect drive wind turbine drivetrains S Sarkar, H Johansson, V Berbyuk Wind Energy 26 (8), 803-825 , 2023 2023 Citations: 4
Enhancing the reliability of floating offshore wind turbine towers subjected to misaligned wind-wave loading using tuned mass damper inerters (TMDIs) B Fitzgerald, J McAuliffe, S Baisthakur, S Sarkar Renewable Energy 211, 522-538 , 2023 2023 Citations: 63
Transient torque reversals in indirect drive wind turbines S Sarkar, H Johansson, V Berbyuk Wind Energy 26 (7), 691-716 , 2023 2023 Citations: 2
Multibody dynamic analysis of onshore horizontal-axis wind turbine A Mitra, S Sarkar, A Chakraborty Non-Destructive Testing and Condition Monitoring Techniques in Wind Energy … , 2023 2023 Citations: 3
Fluid inerter for optimal vibration control of floating offshore wind turbine towers S Sarkar, B Fitzgerald Engineering Structures 266, 114558 , 2022 2022 Citations: 62
Numerical modelling of neutral atmospheric boundary layer flow through heterogeneous forest canopies in complex terrain (a case study of a Swedish wind farm) H Abedi, S Sarkar, H Johansson Renewable Energy 180, 806-828 , 2021 2021 Citations: 36
Use of kane’s method for multi-body dynamic modelling and control of spar-type floating offshore wind turbines S Sarkar, B Fitzgerald Energies 14 (20), 6635 , 2021 2021 Citations: 38
Shape memory alloy‐based centrifugal stiffening for response reduction of horizontal axis wind turbine blade S Das, M Mohamed Sajeer, A Chakraborty, S Sarkar Structural Control and Health Monitoring 28 (3), e2669 , 2021 2021 Citations: 11
Site-specific analysis of on wind turbines in complex terrain: A case study S Sarkar, H Abedi, H Johansson, V Berbyuk WESC2021, Wind Energy Science Conference, The Conference Book (Intro) with … , 2021 2021
Sway vibration control of floating horizontal axis wind turbine by modified spar-torus combination A Mitra, S Sarkar, A Chakraborty, S Das Ocean Engineering 219, 108232 , 2021 2021 Citations: 28
A comparison of soil structure interaction models for dynamic analysis of offshore wind turbines B Fitzgerald, D Igoe, S Sarkar Journal of Physics: Conference Series 1618 (5), 052043 , 2020 2020 Citations: 9
Multi-resolution wavelet pitch controller for spar-type floating offshore wind turbines including wave-current interactions S Sarkar, L Chen, B Fitzgerald, B Basu Journal of Sound and Vibration 470, 115170 , 2020 2020 Citations: 48
Individual blade pitch control of floating offshore wind turbines for load mitigation and power regulation S Sarkar, B Fitzgerald, B Basu IEEE Transactions on Control Systems Technology 29 (1), 305-315 , 2020 2020 Citations: 121
Nonlinear model predictive control to reduce pitch actuation of floating offshore wind turbines S Sarkar, B Fitzgerald, B Basu IFAC-PapersOnLine 53 (2), 12783-12788 , 2020 2020 Citations: 17
Individual blade pitch control strategies for spar-type floating offshore wind turbines S Sarkar Trinity College Dublin , 2020 2020 Citations: 8
MOST CITED SCHOLAR PUBLICATIONS
Vibration control of spar‐type floating offshore wind turbine towers using a tuned mass‐damper‐inerter S Sarkar, B Fitzgerald Structural Control and Health Monitoring 27 (1), e2471 , 2020 2020 Citations: 204
Improved reliability of wind turbine towers with active tuned mass dampers (ATMDs) B Fitzgerald, S Sarkar, A Staino Journal of Sound and Vibration 419, 103-122 , 2018 2018 Citations: 140
Individual blade pitch control of floating offshore wind turbines for load mitigation and power regulation S Sarkar, B Fitzgerald, B Basu IEEE Transactions on Control Systems Technology 29 (1), 305-315 , 2020 2020 Citations: 121
Development of semi-active vibration control strategy for horizontal axis wind turbine tower using multiple magneto-rheological tuned liquid column dampers S Sarkar, A Chakraborty Journal of Sound and Vibration 457, 15-36 , 2019 2019 Citations: 82
Optimal design of semiactive MR‐TLCD for along‐wind vibration control of horizontal axis wind turbine tower S Sarkar, A Chakraborty Structural Control and Health Monitoring 25 (2), e2083 , 2018 2018 Citations: 72
Enhancing the reliability of floating offshore wind turbine towers subjected to misaligned wind-wave loading using tuned mass damper inerters (TMDIs) B Fitzgerald, J McAuliffe, S Baisthakur, S Sarkar Renewable Energy 211, 522-538 , 2023 2023 Citations: 63
Fluid inerter for optimal vibration control of floating offshore wind turbine towers S Sarkar, B Fitzgerald Engineering Structures 266, 114558 , 2022 2022 Citations: 62
Multi-resolution wavelet pitch controller for spar-type floating offshore wind turbines including wave-current interactions S Sarkar, L Chen, B Fitzgerald, B Basu Journal of Sound and Vibration 470, 115170 , 2020 2020 Citations: 48
Use of kane’s method for multi-body dynamic modelling and control of spar-type floating offshore wind turbines S Sarkar, B Fitzgerald Energies 14 (20), 6635 , 2021 2021 Citations: 38
Numerical modelling of neutral atmospheric boundary layer flow through heterogeneous forest canopies in complex terrain (a case study of a Swedish wind farm) H Abedi, S Sarkar, H Johansson Renewable Energy 180, 806-828 , 2021 2021 Citations: 36
Sway vibration control of floating horizontal axis wind turbine by modified spar-torus combination A Mitra, S Sarkar, A Chakraborty, S Das Ocean Engineering 219, 108232 , 2021 2021 Citations: 28
Design of tuned mass damper fluid inerter for wind-induced vibration control of a tall building S Sarkar, B Fitzgerald Journal of Structural Engineering 150 (3), 04023242 , 2024 2024 Citations: 18
Nonlinear model predictive control to reduce pitch actuation of floating offshore wind turbines S Sarkar, B Fitzgerald, B Basu IFAC-PapersOnLine 53 (2), 12783-12788 , 2020 2020 Citations: 17
Shape memory alloy‐based centrifugal stiffening for response reduction of horizontal axis wind turbine blade S Das, M Mohamed Sajeer, A Chakraborty, S Sarkar Structural Control and Health Monitoring 28 (3), e2669 , 2021 2021 Citations: 11
Observer based pitch control for load mitigation and power regulation of floating offshore wind turbines B Fitzgerald, S Sarkar Journal of Physics: Conference Series 2647 (3), 032003 , 2024 2024 Citations: 9
A comparison of soil structure interaction models for dynamic analysis of offshore wind turbines B Fitzgerald, D Igoe, S Sarkar Journal of Physics: Conference Series 1618 (5), 052043 , 2020 2020 Citations: 9
Individual blade pitch control strategies for spar-type floating offshore wind turbines S Sarkar Trinity College Dublin , 2020 2020 Citations: 8
Mitigation of transient torque reversals in indirect drive wind turbine drivetrains S Sarkar, H Johansson, V Berbyuk Wind Energy 26 (8), 803-825 , 2023 2023 Citations: 4
Monopile soil-structure interaction for estimating the dynamic response of an offshore wind turbine D Igoe, B Fitzgerald, S Sarkar Tech. rep , 2019 2019 Citations: 4
Development of a Flexible Multibody Dynamics Wind Turbine Model following Kane’s Method S Sarkar, B Fitzgerald, B Basu Proceedings of the Civil Engineering Research in Ireland, 883-888 , 2018 2018 Citations: 4
