Faculty Publications
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Publications by NITK Faculty
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Item ISMC based variable speed wind turbine for maximum power capture(Institute of Electrical and Electronics Engineers Inc., 2014) RAJENDRAN, S.; Jena, D.This paper presents the nonlinear control for variable speed wind turbine (WT) where the dynamics of WT is derived from single mass model. The main objective is to maximize the energy capture from the wind and reduce the drive train oscillations. In order to control the WT the generator torque is considered as the control input. This torque depends on the optimal rotor speed derived from the effective wind speed. The effective wind speed is estimated from aerodynamic torque and rotor speed by using modified Newton Rapshon (MNR). The conventional techniques such as aero dynamic torque feed forward (ATF) & Indirect speed control (ISC) which does not depend on the effective wind speed, are unable to track the dynamic aspect of the WT. The other disadvantages of the above conventional methods are more power loss and not robust with respect to disturbances and uncertainties. To overcome these weaknesses nonlinear controllers are found to be more suitable than the conventional controller. In this paper a sliding mode control with integral action i.e. integral sliding mode controller (ISMC) is applied to the WT and a modified Newton Rapshon is used to estimate the effective wind speed. The result shows the significance improvement in proposed controllers compared with existing controllers. © 2014 IEEE.Item Backstepping Sliding Mode Control for variable speed wind turbine(Institute of Electrical and Electronics Engineers Inc., 2015) RAJENDRAN, S.; Jena, D.This paper presents the nonlinear control for variable speed wind turbine (VSWT). The dynamics of the wind turbine (WT) are derived from the single mass model. The control objective is to maximize the energy capture from the wind with reduced oscillation on the drive train. The generator torque is considered as the control input and it depends on the optimal rotor speed which is derived from the effective wind speed. The effective wind speed is estimated from the aerodynamic torque and rotor speed by using the modified Newton Rapshon (MNR). Initially the conventional sliding mode controller (SMC) is considered. The control performance of SMC was compared with Backstepping Sliding Mode Control (BSMC) for different level of disturbance. The conventional SMC and proposed BSMC are tested with mathematical model and validated through the different mean wind speed. The result shows the better performance of BSMC and robustness to disturbances. © 2014 IEEE.Item Comparative analysis of different machine learning techniques for condition monitoring of capacitors in a SEPIC converter(Institute of Electrical and Electronics Engineers Inc., 2022) RAJENDRAN, S.; Jena, D.; Diaz-D, M.; Devi, V.S.K.An efficient condition monitoring technique is essential for power converters to avoid unscheduled maintenance. In this work, the condition monitoring of capacitors in a single-ended primary inductance converter (SEPIC) is proposed based on the following machine learning classifiers: K nearest neighbor, support vector machine, back propagation neural network, Naive Bayes, and deep neural network. The feature of the machine learning algorithms is extracted by three node voltages such as voltage across $C$ 1,C2, and load. These features are utilized for training the algorithms. Moreover, the effectiveness of the different classifies are evaluated by considering the accuracy and area under the curve. Further, each algorithm is trained with a different percentage of a dataset. Finally, a comparative study has been made between the algorithms, and the results exhibit that the deep neural network performs better classification than other algorithms. © 2022 IEEE.Item Machine learning based condition monitoring of a DC-link capacitor in a Back-to-Back converter(Institute of Electrical and Electronics Engineers Inc., 2022) RAJENDRAN, S.; Jena, D.; Diaz-D, M.; Devi, V.S.K.The utilization of power electronic converters has increased, and the significance of continuous operation is essential in various applications. Therefore, proper condition monitoring (CM) is vital for power converters to eradicate unpredictable maintenance. However, the existing CM techniques may require additional sensors or injection of controlled voltage to the converters. The following machine learning algorithms, such as a K-nearest neighbors (KNN), Support Vector Machine (SVM), and Naive Bayes (NB), have been proposed to monitor the condition of the dc-link capacitor in a Back-to-Back (BTB) converter. The dc-link voltage is measured, and a wavelet decomposition is employed for the feature extraction. Moreover, the performance index evaluates the efficacy of the different classifiers. Further, different datasets have been considered for the evaluation of the classifiers. From this analysis, it is found that the SVM classifier performs better than others. © 2022 IEEE.Item Comparative analysis of PID, I-PD and fractional order PI-PD for a DC-DC converter(Institute of Electrical and Electronics Engineers Inc., 2022) Shanthini, C.; Devi, V.S.K.; RAJENDRAN, S.; Jena, D.This article presents the design of fractional order PI-PD (FOPI-PD) controller for maintaining the output voltage of a buck converter. Initially, some conventional controllers were adapted, and these controllers introduced the overshoot and large settling time. Therefore, a FOPI-PD has been adapted to overcome the above limitations. The advantage of the FOPI-PD controller is that the error passes through the proportional and integral rather than all the controller gains, which reduces the overall control action. Further, the efficacy of the controllers is investigated in different simulation studies. The results show that the fractional order PI-PD controller significantly enhances the settling time in the presence of different load levels and controller disturbances. © 2022 IEEE.Item Complementary Terminal Sliding Mode Control for Variable Speed Wind Turbine(Institute of Electrical and Electronics Engineers Inc., 2023) RAJENDRAN, S.; Jena, D.; Diaz-D, M.The reduction in transient loads on the drive train influences the life span of the wind turbine when designing the controller for power extraction. In wind turbines, compromises between the efficiency of power extraction and the load level on the drive train have become key issues. Conventional control techniques enhanced energy extraction at the cost of a higher transient load on the drive train. Therefore, this work proposes the complementary terminal sliding mode controller for energy extraction whilst reducing the drive train load. A 600 kW FAST simulator is utilised to validate the performance of the proposed and conventional controllers. Finally, a detailed investigation has been conducted based on energy extraction and mitigation of transient loads under various turbulence models and mean wind speeds. © 2023 IEEE.Item Condition Monitoring of Submodule Capacitors in Modular Multilevel Converter Using Digital Twin(Institute of Electrical and Electronics Engineers Inc., 2023) Painuly, M.; RAJENDRAN, S.; Jena, D.Modular multilevel converter is a fast emerging critical technology in HVDC applications. It comprises of high number of capacitors and reliability of the converter highly depends on the capacitors. Condition monitoring of these capacitors have become necessary to ensure the reliable and efficient operation of the modular multilevel converter system. In this paper, a digital twin concept based condition monitoring method of submodule capacitors of modular multilevel converter is proposed. The proposed method does not require any additional hardware cost and can be simply implemented via software. Furthermore, it monitors the capacitor status of all the submodules at the same time without affecting its operation. The efficacy of the proposed algorithm has been verified with different levels of degradation in the submodule capacitor. Further, the same algorithm is implemented on the three phase modular multilevel converter. The results concluded that the digital twin-based condition monitoring technique could estimate the degradation of the submodule capacitor with high accuracy without additional hardware. © 2023 IEEE.Item Condition monitoring of degradation parameters using dynamic mode decomposition(Institute of Electrical and Electronics Engineers Inc., 2023) Jena, D.; RAJENDRAN, S.The parameter estimation of the nonlinear system demands complex estimation algorithms. Recently data-driven modeling such as Dynamic Mode Decomposition (DMD) and Dynamic Mode Decomposition with Control (DMDc), has gained popularity in the field of parameter estimation and system identification of complex non-linear systems. In this paper, we have applied the DMDc technique for system identification and parameter estimation of the DC motor and DC-DC buck converter with and without knowledge of the input matrix. Further, this helps in condition monitoring and predictive maintenance of different passive components in the buck converter, such as capacitors and resistors. The results conclude that the DMD estimates those parameters within a tolerance limit of 2.2% with a minimum number of data required to capture the dynamics of the system. © 2023 IEEE.Item A review of estimation of effective wind speed based control of wind turbines(Elsevier Ltd, 2015) Jena, D.; RAJENDRAN, S.This paper provides a comprehensive literature review on the estimation of effective wind Speed (EEWS), and EEWS based control techniques applied to wind turbine (WT). Several numbers of good publications have reported the EEWS based control of wind turbine. Wind speed is a driving force for the wind turbine system. In general wind speed measurement is carried out by anemometer which is located at the top of the nacelle. The optimal shaft speed is derived from the exact measurement of wind speed to extract the optimal power output at below rated wind speed. The wind speed provided by the anemometer is measured at a single point of the rotor plane which is not the accurate effective wind speed. At the same time anemometer increases the overall cost, maintenance and reduce the reliability of the overall system. So an accurate EEWS based control technique is required for WT systems to get the optimal power output. In this paper, a detailed description and classification of EEWS and some EEWS based control techniques have been discussed which is based on control strategy and complexity level of WT system. All most all previous work estimates the wind speed using EEWS techniques such as Kalman filter (KF), extended Kalman filter (EKF), neural network (NN) etc., and then different control techniques are applied. In the last section of this paper integral sliding mode control (ISMC) of a WT at below rated speed region is considered. Operating points are determined by proper estimation of effective wind speed, and modified Newton Raphson (MNR) is employed to estimate this. Finally simulation results are presented with a comparison between proposed ISMC, sliding mode control (SMC) and classical controllers such as aerodynamic torque feed forward (ATF) and indirect speed control (ISC). © 2014 Elsevier Ltd. All rights reserved.Item Wind Turbine Emulators—A Review(Multidisciplinary Digital Publishing Institute (MDPI), 2023) RAJENDRAN, S.; Diaz-D, M.; Devi, V.S.K.; Jena, D.; Travieso-Torres, J.C.; Rodríguez, J.Renewable energy sources have become a significant alternative energy source due to the continuing depletion of conventional energy sources and fluctuation in fuel costs. Currently, wind energy is the foremost among all other renewable energy sources. However, modeling and analyzing industrial wind turbines is complex as the wind turbine power ratio and size have steadily increased. Undoubtedly, industrial wind turbines are huge and challenging to keep in research labs; simultaneously, exploring the controller/power converter performance is practically impossible. Therefore, to overcome the above drawbacks, wind turbine emulators have been developed to achieve the static and dynamic characteristics of wind energy conversion systems. This paper aims to present a comprehensive review of the different wind turbine emulators available in the literature. In addition, the implementation of real-time emulators is classified according to the structure and approaches. Furthermore, an extensive analysis of the emulators was presented based on the significant parameters utilized for the real-time wind turbine emulators. Finally, this review analyzes the different emulator topologies according to cost, accuracy, complexity, and hardware implementation. © 2023 by the authors.