Faculty Publications
Permanent URI for this communityhttps://idr.nitk.ac.in/handle/123456789/18736
Publications by NITK Faculty
Browse
8 results
Search Results
Item Performance of power system stabilizers in a fixed series capacitor compensated system(2011) Shashidhara, M.K.; Shubhanga, K.N.In this paper, the performance of two IEEE-type power system stabilizers (PSS), i.e., a slip-signal PSS and a Delta-P-Omega PSS are studied in a fixed series capacitor compensated system employing the IEEE first benchmark system. An eigenvalue analysis of the well-known slip-signal-torsional interaction showed that the slip-signal-interactions occur only when the degree of line compensation is above a certain level depending on the loading condition. The time-domain verifications of the eigen-predictions are carried out through modal speed plots instead of a confusing participation factor-based method. Further, the swing-mode damping performances of PSS are analyzed for different levels of series compensation. This study not only validated the poor swing-mode damping performances of a slip-signal PSS, but also demonstrated that a Delta-P-Omega PSS does not worsen the damping of swing-mode even at higher levels of series compensation which permits a straight forward PSS design. © 2011 IEEE.Item Some aspects of power system stabilizer performance in subsynchronous resonance study(2011) Shashidhara, M.K.; Shubhanga, K.N.In this paper, behavioural aspects of two types of power system stabilizers (PSS), i.e., a slip-signal PSS and a Delta-P-Omega PSS are studied in a fixed series capacitor compensated system employing the IEEE first benchmark system for SSR study. The well-known slip-signal-torsional interaction is studied to understand its dependency on the magnitude of network compensation. From such a study it is noted that the slip-signal-interaction is prominent only at higher degree of line compensation. It is also shown that Delta-P-Omega PSS is immune to such torsional interactions. Further, using the eigenvalue-based study, the swing-mode damping performance of slip-signal PSS and Delta-P-Omega PSS are studied when a system is series compensated. This study not only demonstrated the superiority of Delta-P-Omega PSS, but also validated the poor performance of slip-signal PSS. All these observations are verified by carrying out simulations on PSCAD/EMTDC. To enhance the understanding about the SSR phenomenon, some fundamental observations made in the study are also listed. © 2011 IEEE.Item Rotor speed-instability performance of type-1 WECS employing double-cage induction generator(Institute of Electrical and Electronics Engineers Inc., 2017) Rashmi, n.; Shubhanga, K.N.In this paper, the interfacing of the type-1 wind turbine employing double cage induction generator to the grid is presented. Rotor instability performance of this system is studied and a detailed comparison is done with the single-cage. Steady-state torque-speed characteristics are compared and the results are validated through transient and eigenvalue analysis. The effect of wind turbine characteristics on rotor stability has been brought out. © 2017 IEEE.Item Analytical design of static VAR compensator-based subsynchronous damping controller(Institute of Electrical and Electronics Engineers Inc., 2018) Kotian, S.M.; Shubhanga, K.N.In this paper, using a dynamic phasor model of static VAR compensator (SVC) a method to determine the phase response of a system analytically is presented. Then using the phase compensation method a subsynchronous damping controller (SSDC) for SVC is designed to mitigate subsynchronous resonance (SSR) in series capacitor compensated power systems. The designed SSDC is validated using detailed time-domain simulations in PSCAD/EMTDC. The case studies are carried out on the IEEE first benchmark system. © 2018 IEEE.Item Study of Dynamic Characteristics of Circular Liquid Storage Tanks Using Acoustic Principles(Springer Science and Business Media Deutschland GmbH, 2021) Nimisha, P.; Jayalekshmi, B.R.; Venkataramana, K.Liquid storage tanks are lifeline structures, which should be designed with utmost care. Any damage to a tank, which is used to store hazardous liquid is catastrophic. The estimation of fundamental natural frequencies of liquid storage tanks situated in seismic regions is important for a seismic design. The present study deals with the estimation of natural frequencies of circular steel liquid storage tanks with reference to codal provisions and numerical analysis by using acoustic principles with the aid of FEM software. The study has been carried out for circular tank of diameter 6 m and height 8 m with different liquid depths, viz. 1/3rd, 2/3rd and full tank conditions and stiffness conditions, incorporating the sloshing effect. The natural frequencies obtained by finite element analysis of tanks are compared with those values obtained as per various International codes, viz., IS 1893(part2):2014, API 650 and Eurocode 8. The results show that the convective mode frequencies are matching well whereas, there is slight variation in impulsive mode frequency values obtained as per IS 1893. © 2021, Springer Nature Singapore Pte Ltd.Item Stability Analysis of a Grid-Connected DFIG Operating in Sub-synchronous and Super-synchronous Conditions(Institute of Electrical and Electronics Engineers Inc., 2022) Lazar, A.; Kotian, S.M.This paper examines the impact of power grid strength, power level, rotor side converter (RSC) controller parameters, and shaft parameters on the small-signal stability of a doubly fed induction generator (DFIG)-integrated power system. In each of the parametric variations, both sub-and super-synchronous operating conditions of DFIG are considered. Using the eigenvalue technique the effects of parameter are analyzed and these eigen-inferences are further validated using time-domain simulations. From the analysis it is observed that the in sub-synchronous operating point, weak-grid conditions and RSC controller parameters may result in small-signal instability. © 2022 IEEE.Item A Novel Method for Calculating Steady-State Operating Conditions for DFIG-Based Wind Turbines(Institute of Electrical and Electronics Engineers Inc., 2024) Lazar, A.; Navaneeth, K.; Kotian, S.M.This paper utilizes a modified Newton-Raphson (MNR) iterative technique for steady-state initialization of doubly fed induction generator (DFIG)-based wind turbine (WT) connected to the grid. The MNR technique discussed in this paper is based on the Adomian decomposition method. The steady-state values obtained using the MNR method are compared with those obtained using the conventional Newton-Raphson (NR) method to check the accuracy of the MNR method. Further, the number of iterations taken for both methods to converge was compared. From the case studies, it is noted that the MNR method results in steady-state values, which are identical to those obtained using the NR method with lesser number of iterations. The steady-state values calculated using the MNR method are utilized to carry out the eigenvalue analysis and time-domain simulations of a DFIG-based WT power system. © 2024 IEEE.Item Performance of synchronous machine models in a series-capacitor compensated system(Institute of Electrical and Electronics Engineers Inc., 2014) Kotian, S.M.; Shubhanga, K.N.This paper compares the IEEE-specified generator models such as the equivalent circuit (EC) models and the operational inductance (OI) models to understand their damping performances in the IEEE first-benchmark system for subsynchronous resonance study. These models are found to differ from one another only to an extent they accurately represent the standard transfer functions. By carrying out different case studies an effort is made to analyze the influence of these differences among the models on the damping performance of swing-mode and torsional modes. Through a detailed eigenvalue analysis and time-domain simulations, it is demonstrated that these models offer differing results with respect to swing-mode, thereby strongly influencing the power system stabilizer (PSS) performances, especially when the system is series compensated. Even the torsional mode interactions are found to exhibit dependency on the models employed for the generators. Such a study is expected to provide better insight into the behavior of generator models and controller design/tuning in system analysis. © 1969-2012 IEEE.