Faculty Publications
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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 Dynamic phasor modelling and simulation(Institute of Electrical and Electronics Engineers Inc., 2016) Kotian, S.M.; Shubhanga, K.N.In this paper, the basics of dynamic phasor (DP) modelling has been introduced by employing a simple RL-series circuit. In the example, the actual time-domain simulation and the DP-based simulation are presented in addition to the eigenvalue analysis of the RL-circuit in the DP-domain. With this introduction, following a systematic procedure, the DP-model of a static VAr compensator (SVC) which involves periodic switchings, is derived. To verify this model, a case study with an SVC in the IEEE first benchmark system for subsynchronous resonance (SSR) study has been simulated. The simulation results are also compared with those obtained using a susceptance model for SVC. A PSCAD/EMTDC-based detailed simulation demonstrated that the DP-model offers good-enough accuracy with much less computational effort. © 2015 IEEE.Item A toy model to understand subsynchronous resonance and real-time simulation of the model using RTAI-Linux(Institute of Electrical and Electronics Engineers Inc., 2016) Kotian, S.M.; Latha, A.H.; Shubhanga, K.N.This paper presents a toy- model to demonstrate the concepts of torsional interactions that occur during the subsynchronous resonance (SSR) problem in power systems.The content of the paper evolves as a tutorial and motivates a novice to take up SSR studies on relatively complex systems such as the IEEE first and second benchmark systems which contain many intricate modal interactions. To show the utility of the model and to impart a realistic touch in the lab environment the complete system is simulated in real-time using real-time application interface (RTAI)-enabled Linux platform. Using a peripheral component interconnect (PCI) card, the real-time simulation results are captured on an oscilloscope and are validated using off-line MATLAB simulations. © 2015 IEEE.Item A simulation-based analysis of subsynchronous resonance with TCSC(Universitatea Politehnica din Timisoara blucretiu@yahoo.com, 2013) Batchu, S.; Kotian, S.M.; Shubhanga, K.N.In this paper a time-domain simulation-based SSR analysis has been carried out in PSCAD/EMTDC employing the IEEE first-benchmark system with thyristor-controlled series capacitor (TCSC). Though torsionalmode detuning behavior of a TCSC is well known its tuning performance for certain firing angles is demonstrated employing modal-speed evaluations. An attempt has been made to understand this nature of TCSC by obtaining its frequency response characteristics using frequency scanning technique. From the results it is inferred that the equivalent impedance of TCSC offers fictitious resistive component leading to mode-detuning. However, it is observed that at higher values of firing angle the resistive behavior diminishes thus resulting in mode-tuning.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.