Browsing by Author "Shubhanga, K.N."

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A Comparative Study between Prony and Eigensystem Realization Algorithm for Identification of Electromechanical Modes
(Institute of Electrical and Electronics Engineers Inc., 2018) Sarkar, N.; Rao, K.; Shubhanga, K.N.
Two measurement-based ring-down electromechanical mode identification algorithms, namely Prony and Eigensystem Realization Algorithm (ERA) are taken up for a comparative study. Since the number of excited modes might vary in a practical power system, it is not easy to determine the model order. This requires an iterative procedure in case of Prony whereas a Singular Value Decomposition (SVD)-based technique achieves this directly in case of ERA as demonstrated through two case studies. It is further shown that ERA estimates the signal better and generates less number of trivial modes as compared to Prony. Â© 2018 IEEE.
A comparison of power system signal detrending algorithms
(Institute of Electrical and Electronics Engineers Inc., 2018) Rao, K.; Shubhanga, K.N.
Wide Area Measurement Systems (WAMS) have facilitated tracking of oscillations in power system response signals. This has provided an impetus for application of signal measurement-based modal detection methods such as matrix pencil and Prony analysis. Detrending, which means removal of trend in a signal, is a pre-requisite for effective functioning of these modal detection methods. In this work, performance of three methods of detrending viz., Center-of-Inertia (COI)-based detrending, MATLAB function-based detrending and 'Zhou' detrending are compared with particular reference to power system signals. It is indicated that COI-based detrending is better suited to detection of modes from slip signals of generators. Â© 2017 IEEE.
A Comparison of SVD-Augmented Prony Algorithms for Noisy Power System Signals
(Institute of Electrical and Electronics Engineers Inc., 2023) Rao, K.; Shubhanga, K.N.
The conventional Prony algorithm, which is the most prominent power system ring-down mode identification method, fails if the test signal is noisy [with a signal-to-noise ratio (SNR) below 20 dB]. The performance of Prony algorithm can be improved through singular value decomposition (SVD)-based rank reduction of the data matrix. Principal eigenvector (PE)-Prony and total least squares (TLS)-Prony are two known formulations of SVD-augmented Prony algorithms. In both PE-Prony and TLS-Prony algorithms, the Toeplitz structure of the linear prediction data matrix is lost upon SVD-based noise filtering. On the other hand, structured total least squares (STLS)-Prony algorithm retains the Toeplitz structure even after SVD-based filtering and is hence expected to perform better. But a formulation of STLS-Prony algorithm for power systems is not available in the literature. Hence, the same is developed successfully in this paper. As a prelude to the formulation of STLS-Prony algorithm, PE-Prony and TLS-Prony analyses of power system signals are discussed in detail, bringing out their nuances. Further, case studies are carried out on some benchmark power systems to demonstrate that all the three algorithms work successfully even at an SNR of 1 dB when the test signal has only inter-area modes. It is also shown that the performance of STLS-Prony algorithm is superior when the test signal has a highly damped local mode. Further, it is illustrated that by virtue of structure-preserving property, STLS-Prony algorithm is endowed with a unique filtering attribute although it has a longer execution time. © 2013 IEEE.
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.
A study of starting methods for an induction motor using an arbitrary waveform generator
(Institute of Electrical and Electronics Engineers Inc., 2016) Banerjee, A.; Banerjee, A.; Rana, D.P.S.; Shubhanga, K.N.
In this paper the use of an arbitrary waveform generator to generate desired signals in real-time is illustrated by simulating an induction motor operation along with various starting techniques. An off-line digital simulation of an induction motor is carried out on MATLAB/SIMULINK. The resulting sample-data files pertaining to signals such as electromagnetic torque and rotor speed are used in the arbitrary waveform generator to trace waveforms on an oscilloscope in real-time. This arbitrary waveform generator is developed on the Real-Time Application Interface (RTAI) enabled-Linux platform. The paper presents results of some case studies carried out by employing different starting techniques such as direct on-line and star-delta starting methods. Such a tool will be of great help in enhancing the class room learning. Â© 2015 IEEE.
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. Â© 2015 IEEE.
An Exposition ofÂ Digital Taylor-Fourier Transform
(Springer Science and Business Media Deutschland GmbH, 2024) Rao, K.; Shubhanga, K.N.
Digital Taylor-Fourier Transform (DTFT) is a Taylor series-based extension to Discrete Fourier Transform. It is becoming popular due to its ability to estimate off-nominal frequency phasors accurately, which is lacking in DFT, the conventional technique used in Phasor Measurement Units (PMUs). In light of this, a lucid presentation of the mathematical formulation of DTFT is considered instructive and hence the same is attempted here. Further, the ability of DTFT filter to accurately estimate off-nominal frequency phasors, off-nominal frequency harmonics and exponentially varying sinusoids is illustrated and reasoned out. Â© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd 2024.
An integrated PMU architecture for power system applications
(De Gruyter Open Ltd, 2022) Aalam, M.K.; Shubhanga, K.N.
Time synchronized phasors obtained using Phasor Measurement Units (PMU) spread across wide areas have revolutionized power system monitoring and control. These synchronized measurements must be accurate and fast in order to comply with the latest IEEE standards for synchrophasor measurements. The speed at which a PMU provides an output depends on the group delay associated with that PMU and the permissible group delay in-turn decides the utility of a PMU for either control or measurement application. Based on the group delay compensation techniques, in the literature, two individual types of PMUs, such as causal and non-causal PMUs have been introduced. This paper presents an approach where both causal and non-causal PMUs are combined in an integrated PMU architecture. This method not only illustrates the group delay performance of two PMUs in a single module, but also can be used for multiple functions. In this environment several PMU algorithms have been compared with respect to their group delays and their effect on the response time. Application of the integrated PMU architecture to a four-machine 10-bus power system has been demonstrated using a six-input PMU with three-phase voltage and current signals as inputs. Different causal compensation schemes are introduced due to the availability of voltage and current-based frequency and ROCOF signals. Impact of these compensation schemes on PMU accuracy is evaluated through the Total Vector Error (TVE) index. The influence of these compensation schemes on measurements like power and impedance is also investigated. Finally, outputs from the integrated PMU architecture are fed into a Power System Stabilizer (PSS) to control the small-signal stability performance of a power system during dynamic conditions. © 2021 Walter de Gruyter GmbH, Berlin/Boston.
Analysis of a laboratory scale three-phase FC-TCR-based static VAr compensator
(2017) Gajanana, Abhyankar, B.; Shubhanga, K.N.; Girisha, Navada, H.
This paper presents the design and steady-state analysis of a Fixed Capacitor-Thyristor Controlled Reactor (FC-TCR)-based Static VAr Compensator (SVC). Reactive power compensation is demonstrated through the fundamental frequency analysis of the samples acquired from the designed system. The performance of the SVC in the presence of line reactance is also discussed. National Instrument (NI) based data acquisition system is used to perform the steady-state analysis. Besides, a few transient responses are also captured using the data acquisition system. � 2017 IEEE.
Analysis of a laboratory scale three-phase FC-TCR-based static VAr compensator
(Institute of Electrical and Electronics Engineers Inc., 2017) Gajanana Abhyankar, B.; Shubhanga, K.N.; Girisha Navada, H.
This paper presents the design and steady-state analysis of a Fixed Capacitor-Thyristor Controlled Reactor (FC-TCR)-based Static VAr Compensator (SVC). Reactive power compensation is demonstrated through the fundamental frequency analysis of the samples acquired from the designed system. The performance of the SVC in the presence of line reactance is also discussed. National Instrument (NI) based data acquisition system is used to perform the steady-state analysis. Besides, a few transient responses are also captured using the data acquisition system. Â© 2017 IEEE.
Analytical design of static VAR compensator-based subsynchronous damping controller
(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.
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. Â© 2018 IEEE.
Circuit analysis in the time-domain: Operational approach to form the system-matrix exponential and to obtain the circuit natural response therefrom
(2014) Rao, I.R.; Shubhanga, K.N.
A time-domain operational method for the dynamic analysis of force-free Linear Time-Invariant (LTI) lumped-parameter electrical systems is presented. Starting from the state model of the system, a purely time-domain technique for obtaining the matrix exponential (state-transition matrix) has been developed. This approach preserves the time-domain identity of all the network variables (unlike the transformational approaches) and facilitates analytical, closed-form solutions for number-imposed system parameters (unlike numerical techniques). Furthermore, it provides the 'algebrization'-advantage in the time-domain itself, in which the system variables are directly observable. This obviates the need for any artificial and cumbersome transformations (both direct and inverse). This approach has been here employed to formulate the solution process of the natural (force-free) response of a generic LTI lumped-parameter electrical network of any given order, starting from the vectorized set of time-domain differential equations that collectively govern the behaviour of the said network. Some crucial aspects regarding system modeling have been highlighted. The proposed method is illustrated by examples which demonstrate the ease with which the natural response of an LTI system could be obtained, for specified initial conditions. � 2014 IEEE.
Circuit analysis in the time-domain: Operational approach to form the system-matrix exponential and to obtain the circuit natural response therefrom
(IEEE Computer Society help@computer.org, 2014) Rao, I.R.; Shubhanga, K.N.
A time-domain operational method for the dynamic analysis of force-free Linear Time-Invariant (LTI) lumped-parameter electrical systems is presented. Starting from the state model of the system, a purely time-domain technique for obtaining the matrix exponential (state-transition matrix) has been developed. This approach preserves the time-domain identity of all the network variables (unlike the transformational approaches) and facilitates analytical, closed-form solutions for number-imposed system parameters (unlike numerical techniques). Furthermore, it provides the 'algebrization'-advantage in the time-domain itself, in which the system variables are directly observable. This obviates the need for any artificial and cumbersome transformations (both direct and inverse). This approach has been here employed to formulate the solution process of the natural (force-free) response of a generic LTI lumped-parameter electrical network of any given order, starting from the vectorized set of time-domain differential equations that collectively govern the behaviour of the said network. Some crucial aspects regarding system modeling have been highlighted. The proposed method is illustrated by examples which demonstrate the ease with which the natural response of an LTI system could be obtained, for specified initial conditions. Â© 2014 IEEE.
A Comparative Study between Prony and Eigensystem Realization Algorithm for Identification of Electromechanical Modes
(2018) Sarkar, N.; Rao, K.; Shubhanga, K.N.
Two measurement-based ring-down electromechanical mode identification algorithms, namely Prony and Eigensystem Realization Algorithm (ERA) are taken up for a comparative study. Since the number of excited modes might vary in a practical power system, it is not easy to determine the model order. This requires an iterative procedure in case of Prony whereas a Singular Value Decomposition (SVD)-based technique achieves this directly in case of ERA as demonstrated through two case studies. It is further shown that ERA estimates the signal better and generates less number of trivial modes as compared to Prony. � 2018 IEEE.
A comparison of power system signal detrending algorithms
(2018) Rao, K.; Shubhanga, K.N.
Wide Area Measurement Systems (WAMS) have facilitated tracking of oscillations in power system response signals. This has provided an impetus for application of signal measurement-based modal detection methods such as matrix pencil and Prony analysis. Detrending, which means removal of trend in a signal, is a pre-requisite for effective functioning of these modal detection methods. In this work, performance of three methods of detrending viz., Center-of-Inertia (COI)-based detrending, MATLAB function-based detrending and 'Zhou' detrending are compared with particular reference to power system signals. It is indicated that COI-based detrending is better suited to detection of modes from slip signals of generators. � 2017 IEEE.
Current injection modelling based large-signal analysis of a grid-connected solar photovoltaic power system
(2017) Singh, S.V.; Shubhanga, K.N.
In recent years, penetration level of the grid-connected renewables has been increasing. These grid integration, affects the steady state as well as dynamic behavior of the power system network. In this paper, the conventional loadflow programme is modified to accommodate grid-connected solar photovoltaic (SPV) power system. A model of SPV-integrated power system is developed to carry out large-signal analysis. Various test cases are illustrated to appreciate the network behavior for varying meteorological variable and different grid-specifications pertaining to SPV power system. Critical clearing time of SPV-integrated power system is estimated. � 2016 IEEE.
Current injection modelling based large-signal analysis of a grid-connected solar photovoltaic power system
(Institute of Electrical and Electronics Engineers Inc., 2017) Singh, S.V.; Shubhanga, K.N.
In recent years, penetration level of the grid-connected renewables has been increasing. These grid integration, affects the steady state as well as dynamic behavior of the power system network. In this paper, the conventional loadflow programme is modified to accommodate grid-connected solar photovoltaic (SPV) power system. A model of SPV-integrated power system is developed to carry out large-signal analysis. Various test cases are illustrated to appreciate the network behavior for varying meteorological variable and different grid-specifications pertaining to SPV power system. Critical clearing time of SPV-integrated power system is estimated. Â© 2016 IEEE.
Design and implementation of a laboratory scale three-phase thyristor controlled reactor
(2017) Abhyankar, B.G.; Shubhanga, K.N.; Navada, H.G.
This paper presents design, implementation and analysis of a laboratory scale three-phase thyristor controlled reactor (TCR). The performance of the TCR is demonstrated through many case studies for different connections of the TCR branches. A detailed harmonic analysis is carried out to understand the harmonic behaviour of the setup. The fundamental reactance characteristics of the TCR is also obtained experimentally and compared with ideal characteristics. A simulation model is developed using 'MATLAB' to verify the oscilloscope captured-waveforms. This setup is found to be a good learning resource for introducing variable reactance nature of a TCR. � 2017 IEEE.
Design and implementation of a laboratory scale three-phase thyristor controlled reactor
(Institute of Electrical and Electronics Engineers Inc., 2017) Abhyankar, B.G.; Shubhanga, K.N.; Navada, H.G.
This paper presents design, implementation and analysis of a laboratory scale three-phase thyristor controlled reactor (TCR). The performance of the TCR is demonstrated through many case studies for different connections of the TCR branches. A detailed harmonic analysis is carried out to understand the harmonic behaviour of the setup. The fundamental reactance characteristics of the TCR is also obtained experimentally and compared with ideal characteristics. A simulation model is developed using 'MATLAB' to verify the oscilloscope captured-waveforms. This setup is found to be a good learning resource for introducing variable reactance nature of a TCR. Â© 2017 IEEE.