Faculty Publications
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Item Response-type modelling of a two-terminal HVDC link for power system stability analysis(Institute of Electrical and Electronics Engineers Inc., 2017) Johnson, T.; Shubhanga, K.N.In this paper, the dynamic performance of a two-terminal High Voltage Direct Current (HVDC) link has been evaluated by employing a response-type model. Case studies have been carried out on a 10-bus two-area modified power system with an HVDC link embedded in the system. Here, the real power flows in the HVDC link are changed from one level to another, to understand the model behaviour. © 2017 IEEE.Item Loop flow performance of interconnected power systems with HVDC links(Institute of Electrical and Electronics Engineers Inc., 2017) Johnson, T.; Shubhanga, K.N.In this paper, the influence of HVDC links in interconnected power systems to prevent loop flow, is analysed. To enable this, a two-terminal HVDC link has been modelled in FDLF-based conventional power flow programme. The results of the case studies are presented using a 10-bus two-area modified power system and a 14-bus the IEEE test system, by replacing the AC lines by HVDC links with power-reference specification. © 2016 IEEE.Item Significance of reactive power loss and its application to system voltage stability(Institute of Electrical and Electronics Engineers Inc., 2018) Moger, T.; Johnson, T.; Dhadbanjan, T.In this paper, the significance of reactive power loss and its application to system voltage stability is presented. The reactive power loss allocation at the load-buses is computed from the reactive power support and loss allocation algorithm using modified Y-bus approach. Further, it is computed for the various load conditions in the system upto the maximum loadability point. The proposed approach is illustrated on a sample 5-bus system and also tested on a 11-bus practical equivalent system of Indian southern region power grid. A comparative analysis is also carried out with the continuation power flow method to highlight the features of the proposed approach. It can be observed from the simulation results that the reactive power loss allocation at load-buses give the clear indication about the system reactive power issues, which in-turn give an indication about the system voltage instability/collapse problem. © 2018 IEEE.Item A Comparative Analysis of Speed Estimation Techniques of Induction Motor Drive using Non-linear Kalman Filters(Institute of Electrical and Electronics Engineers Inc., 2021) Banu, S.; Johnson, T.; Moger, T.In this paper the use of non-linear kalman filters to estimate the rotor speed of an induction motor drive is studied in detail. The general structure of the extended Kalman filter (EKF), unscented kalman filter (UKF) and cubature kalman filter (CKF) is reviewed, and the various system vectors and matrices are defined. By including the rotor speed as a state variable, these non-linear kalman filter equations are established from a discrete two-axis model of the three-phase induction motor. Using MATLAB/Simulink, simulation of the speed estimation algorithm is carried out for an induction motor with Space Vector Modulation (SVM) drive. The experimental results obtained are compared for feasibility and performance, and it is observed that CKF is the most accurate among the three kalman filters even during parameter changes due to motor temperature and speed variations. © 2021 IEEE.Item Case Studies of Event Detection for Indian Power System using Signal Processing Methods(Institute of Electrical and Electronics Engineers Inc., 2021) Johnson, T.; Pathak, A.; Arya, S.A.; Dahanuwala, S.D.; Gachhi, P.; Moger, T.With the deployment of phasor measurement units (PMU) and wide area measurement system (WAMS), it is feasible to have an insight into the real-time events occurring in power systems based on measured PMU data. Any critical disturbance occurring in a power system is noted as an Event. The analysis carried out in this paper are based on PMU data inferences derived using various signal processing methods like Fast Fourier Transform, Yule-Walker Spectral Analysis, Matrix Pencil and Min-Max. The results of each of these methods have been described and an intersection of results from two or more methods are finally identified as Events. The results have been compiled on two different data sets: one for the Northern Region of Indian Power Grid and another for entire Indian power system. The data with respect to Northern Region was collected on 20th May 2020, during the cyclone Amphan, which caused many disruptions in electric power network. The second data was gathered from 30 stations all over India during an electromechanical oscillation fault. © 2021 IEEE.Item A Comparative Study of Bayesian based filters for Dynamic State Estimation in Power Systems(Institute of Electrical and Electronics Engineers Inc., 2021) Banu, S.; Johnson, T.; Moger, T.Dynamic state estimation of a power system is the first prerequisite for control and stability prediction under transient conditions. Among the states of synchronous machine, precise, accurate, and timely information about rotor angle and speed deviation can be useful to enhance power system reliability and stability. In this paper, the popular variants of Kalman filter are used to estimate the main states of synchronous generators of an SMIB and IEEE 3-generators 9-bus test systems. A case study using a simple power system model is presented to illustrate the comparison between effectiveness of proposed approaches. © 2021 IEEE.Item Latest Trends in Electromechanical Dynamic State Estimation for Electric Power Grid(Institute of Electrical and Electronics Engineers Inc., 2022) Johnson, T.; Moger, T.Dynamic state estimation is the starting point for the further control and and protection strategies implementation for a secure electric grid. This basically provides the real-time operating status using the electromechanical state variables. This is essential especially after small or large disturbance events in the system. A critical review is presented in this paper to open up the research opportunities and scope for new researchers in this field. © 2022 IEEE.Item Review of Advancements in Forecasting-aided State Estimation based on Kalman Filter Approach for Voltage Profile of Power Systems(Institute of Electrical and Electronics Engineers Inc., 2022) Johnson, T.; Moger, T.Forecasting-aided state estimation (FASE) is per-formed for power system to help in monitoring and control of the system. The estimation is carried out employing the data from remote terminal units along with that from phasor measurement units. So far for FASE, it is assumed that the variations in the system variables, for instance load demand variations at a bus are slow. Quick variations in the states of an electric grid are hence not included for the study. To predict the states at a time instant in between receiving the two measurement datasets from the measurement system, a state forecasting approach is being used. The filtering step is carried out with the help of a Kalman filter approach. This aids in the estimation of power system states during periods when field data are unavailable. © 2022 IEEE.Item Latest Trends in Event Detection Techniques in Power Systems(Institute of Electrical and Electronics Engineers Inc., 2022) Johnson, T.; Moger, T.Numerous issues come up in an electrical power networks. The magnitudes of these disturbances may however be a deciding factor for them to be critical or not. Disturbance is the variation of any of the electrical quantities monitored from its normal operating range. Some disturbances that may cause electric grid interruption or degradation have been categorized as Events, under the focus of this study. These occurrences must be dealt with as soon as reasonably practicable, as they could bring huge losses to power generation organizations. The literature survey carried out in this paper highlights the challenges and deficiencies of the existing methods. Thus, giving directions for future scope of improvements needed in this research topic to help new researchers. © 2022 IEEE.Item A critical review of methods for optimal placement of phasor measurement units(John Wiley and Sons Ltd, 2021) Johnson, T.; Moger, T.Situational awareness of the electric power system is the need of the hour. This is in the wake of recent blackouts in various parts of the world. These blackouts could have been prevented with better telemetry and real-time monitoring of power system states. A fast and reliable measuring system with devices optimally employed across the network shall enable reliable system operation. Faster situational awareness and visualization helps the system operator to take faster preventive measures and maintain system stability. Wide Area Monitoring System uses phasor measurement units (PMUs) to measure power system states. PMUs measure synchronously real-time voltages at various buses and current phasors, which are flowing toward these buses. But, there is a need to optimally find the locations for installation of PMUs in the network for an observable system, with minimum investment. This optimal placement of PMUs (OPP) is a binary optimization problem, combinatorial in nature. In this paper, progress achieved until now in the field of OPP studies are consolidated. A discussion on the characteristics of problem formulations and shortcomings of methods and constraints considered has been done. Challenges have been highlighted to provide a good foundation for new researchers. © 2020 John Wiley & Sons Ltd