Saptarshi Sarkar

@ri.se

Researcher
RISE Research Institutes of Sweden AB



                       

https://researchid.co/saptarshisarkar

RESEARCH, TEACHING, or OTHER INTERESTS

Renewable Energy, Sustainability and the Environment, Civil and Structural Engineering, Mechanical Engineering, Control and Systems Engineering

22

Scopus Publications

711

Scholar Citations

12

Scholar h-index

12

Scholar i10-index

Scopus Publications

  • Design of Tuned Mass Damper Fluid Inerter for Wind-Induced Vibration Control of a Tall Building
    Saptarshi Sarkar and Breiffni Fitzgerald
    American Society of Civil Engineers (ASCE)

  • Observer based pitch control for load mitigation and power regulation of floating offshore wind turbines
    Breiffni Fitzgerald and Saptarshi Sarkar
    IOP Publishing
    Abstract 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, and A Wickström
    IOP Publishing
    Abstract 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, and Viktor Berbyuk
    Wiley
    AbstractBearing 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, and Viktor Berbyuk
    Wiley
    AbstractThe 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.

  • Multibody dynamic analysis of onshore horizontal-axis wind turbine
    Arka Mitra, Saptarshi Sarkar, and Arunasis Chakraborty
    Elsevier



  • Use of kane’s method for multi-body dynamic modelling and control of spar-type floating offshore wind turbines
    Saptarshi Sarkar and Breiffni Fitzgerald
    MDPI AG
    This paper demonstrates the use of Kane’s method to derive equations of motion for a spar-type floating offshore wind turbine taking into account the flexibility of the members. The recently emerged Kane’s method reduces the effort required to derive equations of motion for complex multi-body systems, making them simpler to model and more readily solved by computers. Further, the installation procedure of external vibration control devices on the wind turbine using Kane’s method is described, and the ease of using this method has been demonstrated. A tuned mass damper inerter (TMDI) is installed in the tower for illustration. The excellent vibration mitigation properties of the TMDI are also presented in this paper.

  • Shape memory alloy-based centrifugal stiffening for response reduction of horizontal axis wind turbine blade
    Sourav Das, M. Mohamed Sajeer, Arunasis Chakraborty, and Saptarshi Sarkar
    Hindawi Limited
    The aim of this study is to reduce the deformation of large horizontal axis wind turbine blades using shape memory alloy (SMA)‐based centrifugal stiffening. A discrete model considering dominant modes of the tower, drive train and blades is developed in this study to demonstrate the performance of the proposed stiffening strategy. Here, super‐elastic behaviour of SMA is characterized by Graesser‐Cozzarelli model. Aerodynamic loads acting on the blades are evaluated using blade element momentum theory. The response is simulated using aerodynamic damping, which is estimated in each mode of vibration. Numerical results presented in this paper clearly show the significance of the proposed SMA‐based stiffening to reduce blade vibration. Sensitivity analysis is also carried out to demonstrate the performance envelop of the proposed stiffening strategy over the operational range of the benchmark 5‐MW wind turbine. The study clearly highlights the performance enhancement in terms of deformation in two orthogonal directions and design in terms of longitudinal stress that ultimately improve the serviceability of the blade.

  • Individual Blade Pitch Control of Floating Offshore Wind Turbines for Load Mitigation and Power Regulation
    Saptarshi Sarkar, Breiffni Fitzgerald, and Biswajit Basu
    Institute of Electrical and Electronics Engineers (IEEE)
    This article proposes a new strategy for individual blade pitch control to regulate power production while simultaneously alleviating structural loads on spar-type floating offshore wind turbines. Individual blade pitch control types of algorithms for offshore wind turbines are sparse in the literature though there are expected benefits from experience on such types of controllers for onshore wind turbines. Wind turbine blade pitch actuators are primarily used to maintain the rated power production at the above-rated wind speeds, and therefore, control algorithms are usually developed only to regulate power production. The scope of reducing structural loads using individual pitch control has been proven to be very promising over the last decade, and numerous individual pitch control algorithms have been proposed by researchers. However, reduction in structural loads often results in a degradation in power production and regulation. Furthermore, improving power regulation often has a detrimental effect on the floating platform motion. In this article, a new control strategy is proposed to achieve the two competing objectives. The proposed controller combines a low-authority linear-quadratic (LQ) controller with an integral action to reduce the 1P (once per revolution) aerodynamic loads while regulating power production using the same pitch actuators that are traditionally used only to optimize power production. The proposed controller is compared against the baseline controller (BC) used by the state-of-the-art wind turbine simulator FAST using a high-fidelity aeroelastic offshore wind turbine model. Numerical results show that the proposed controller offers improved performance in optimizing power production and reducing wind turbine and platform loads compared with the BC over an envelope of wind-wave loading environment.

  • Sway vibration control of floating horizontal axis wind turbine by modified spar-torus combination
    Arka Mitra, Saptarshi Sarkar, Arunasis Chakraborty, and Sourav Das
    Elsevier BV

  • A Comparison of Soil Structure Interaction Models for Dynamic Analysis of Offshore Wind Turbines
    Breiffni Fitzgerald, David Igoe, and Saptarshi Sarkar
    IOP Publishing
    Abstract This paper compares the dynamic response of an OWT structure where the below ground pile-soil behaviour is modelled using (i) the conventional API ‘p-y’ approach and (ii) the ‘PISA’ approach. A nonlinear aero-elastic code is used to model the structural dynamics of the OWT and coupled to the geotechnical model. The dynamic behaviour (natural frequencies) and fatigue loads of the turbine tower and monopile are estimated and compared using both the API and PISA approaches. A limited number of load cases were considered in the dynamic analysis with varied met-ocean conditions. It was found that the stiffer springs estimated by the PISA approach reduce the mean displacement of the tower in both the fore-aft and side-to-side directions. However, the increased monopile stiffness leads to a slightly increased amplitude of oscillations, particularly in the lightly damped side-to-side direction.


  • Nonlinear model predictive control to reduce pitch actuation of floating offshore wind turbines
    Saptarshi Sarkar, Breiffni Fitzgerald, and Biswajit Basu
    Elsevier BV

  • Magneto-rheological tuned liquid column dampers to improve reliability of wind turbine towers
    S. Sarkar, B. Fitzgerald, B. Basu, and Arunasis Chakraborty
    Springer Singapore

  • Vibration control of spar-type floating offshore wind turbine towers using a tuned mass-damper-inerter
    Saptarshi Sarkar and Breiffni Fitzgerald
    Hindawi Limited
    This paper investigates the use of a passive tuned mass‐damper‐inerter (TMDI) for vibration control of spar‐type floating offshore wind turbine towers. The TMDI is a relatively new concept as a passive vibration control device. The configuration consists of an “inerter” attached to the tuned mass, parallel to the spring and damper of a classical tuned mass damper (TMD). The inerter provides a mass amplification effect on the classical TMD. The presence of the inerter virtually increases the mass of the damper leading to greater vibration control capabilities. This enables one to achieve improved vibration control using a lighter damper. Using a lightweight damper is particularly important for an offshore wind turbine because increasing mass on top of the tower can destabilize the overall system and increase tower vibrations, as demonstrated in this paper. The development of a passive TMDI for an offshore wind turbine tower has been proposed in detail in this work. Numerical simulations have been performed and results are presented demonstrating the impressive vibration control capabilities of this new device under various stochastic wind‐wave loads. It has been shown that the TMDI has considerable advantages over the classical TMD, achieving impressive response reductions with reductions in the stroke of the tuned mass. The TMDI has been shown to be a promising candidate for replacing the classical TMD for offshore wind applications.


  • Improved reliability of wind turbine towers with active tuned mass dampers (ATMDs)
    Breiffni Fitzgerald, Saptarshi Sarkar, and Andrea Staino
    Elsevier BV

  • Optimal design of semiactive MR-TLCD for along-wind vibration control of horizontal axis wind turbine tower
    Saptarshi Sarkar and Arunasis Chakraborty
    Hindawi Limited
    Present study aims to address the design of smart vibration control scheme for horizontal axis wind turbine tower using magneto‐rheological tuned liquid column damper. With this in view, a reduced order model of the blade‐tower system is used, considering centrifugal stiffening and gravitational effects that lead to time‐dependent dynamic stiffness matrix. Aerodynamic load on the blades is modeled using blade element momentum theory. Semiactive control law in linear quadratic regulator framework is developed to mitigate the along‐wind vibration of the tower. To implement the control law, multiblade coordinate transformation is adopted that converts the system matrices in the nonrotating framework to tackle its time dependency. The performance of the proposed control algorithm is demonstrated using numerical simulations with and without controller. Clipped optimality of the control force is imposed to keep the parameters of magneto‐rheological tuned liquid column damper in the feasible range. Finally, sensitivity analysis is carried out to demonstrate the performance envelope of the proposed control algorithm for different operational scenario. Results presented in this paper clearly demonstrate that the proposed algorithm can be employed for effective along‐wind vibration control of large HWAT tower.

  • Numerical modelling of a monopile for estimating the natural frequency of an offshore wind turbine
    David Igoe, Luke J. Prendergast, Breiffni Fitzgerald, and Saptarshi Sarkar
    Springer International Publishing

RECENT SCHOLAR PUBLICATIONS

  • 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

  • Optimizing Wind Farm Efficiency through Active Yaw Control: A Neural Network-Aided Game Theory Approach
    H Abedi, S Sarkar, A Wickstrm
    Journal of Physics: Conference Series 2767 (9), 092020 2024

  • 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

  • Mitigation of transient torque reversals in indirect drive wind turbine drivetrains
    S Sarkar, H Johansson, V Berbyuk
    Wind Energy 26 (8), 803-825 2023

  • 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

  • Transient torque reversals in indirect drive wind turbines
    S Sarkar, H Johansson, V Berbyuk
    Wind Energy 26 (7), 691-716 2023

  • 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

  • Fluid inerter for optimal vibration control of floating offshore wind turbine towers
    S Sarkar, B Fitzgerald
    Engineering Structures 266, 114558 2022

  • 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

  • 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

  • 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

  • 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

  • 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

  • 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

  • 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

  • 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

  • Individual blade pitch control strategies for spar-type floating offshore wind turbines
    S Sarkar
    Trinity College Dublin 2020

  • 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

  • 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

  • Monopile soil-structure interaction for estimating the dynamic response of an offshore wind turbine
    D Igoe, B Fitzgerald, S Sarkar
    Tech. rep 2019

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
    Citations: 155

  • 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
    Citations: 115

  • 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
    Citations: 85

  • 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
    Citations: 65

  • 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
    Citations: 56

  • Fluid inerter for optimal vibration control of floating offshore wind turbine towers
    S Sarkar, B Fitzgerald
    Engineering Structures 266, 114558 2022
    Citations: 42

  • 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
    Citations: 38

  • 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
    Citations: 30

  • 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
    Citations: 27

  • 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
    Citations: 23

  • 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
    Citations: 22

  • 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
    Citations: 13

  • 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
    Citations: 8

  • 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
    Citations: 8

  • Individual blade pitch control strategies for spar-type floating offshore wind turbines
    S Sarkar
    Trinity College Dublin 2020
    Citations: 7

  • 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
    Citations: 5

  • 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
    Citations: 3

  • 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
    Citations: 3

  • 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
    Citations: 2

  • Monopile soil-structure interaction for estimating the dynamic response of an offshore wind turbine
    D Igoe, B Fitzgerald, S Sarkar
    Tech. rep 2019
    Citations: 2