Faculty Publications
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Publications by NITK Faculty
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Item N and p doped poly(3,4-ethylenedioxythiophene) electrode materials for symmetric redox supercapacitors(2007) Bhat, D.K.; Muthu, M.S.A symmetric redox supercapacitor has been fabricated based on n and p doped Poly(3,4-ethylenedioxythiophene)(PEDOT) coated on stainless steel (SS) electrodes. The characterization and performance of the supercapacitor has been studied by FTIR, Cyclic Voltammetry and AC Impedance spectroscopy. The supercapacitor showed a maximum specific capacitance of 121 F g-1 at a scan rate of 10 mV s-1. The time constant calculated for the supercapacitor through the active-reactive power behavior measurement was 12 milliseconds indicating the suitability of the system for efficient use at low frequency range. © 2007 Springer Science+Business Media, LLC.Item Distributed load flow analysis using graph theory(2011) Sharma, D.P.; Chaturvedi, A.; Purohit, G.; Shivarudraswamy, R.In today scenario, to meet enhanced demand imposed by domestic, commercial and industrial consumers, various operational & control activities of Radial Distribution Network (RDN) requires a focused attention. Irrespective of sub-domains research aspects of RDN like network reconfiguration, reactive power compensation and economic load scheduling etc, network performance parameters are usually estimated by an iterative process and is commonly known as load (power) flow algorithm. In this paper, a simple mechanism is presented to implement the load flow analysis (LFA) algorithm. The reported algorithm utilizes graph theory principles and is tested on a 69- bus RDN.Item Coordinated voltage regulation of distribution network with distributed generators and multiple voltage-control devices(2012) Shivarudraswamy, R.; Gaonkar, D.N.In recent years, there has been a considerable increase in the number of generators connected to distribution networks. While offering a number of benefits and opportunities, increasing penetration of distributed generation systems can cause several technical concerns. One major concern is the rise in steady-state voltage level of a distribution system. This is very important, as distribution networks are traditionally designed to maintain customer voltage constant, within tolerance limit as dictated by statute. The present practice of limiting generation capacity cannot be a solution, as it leads to under-utilization of distributed generation sources. In this article, coordinated voltage regulation of distribution system with distributed generators is presented. The developed method uses the genetic algorithm to determine the optimal operating point for multiple voltage-control devices. The simulated results using the developed method are presented in this article, considering the time-varying load profile. The fuzzy-clustering technique is also employed to obtain the load pattern for the simulation. The reported results show that the method presented is capable of providing the voltage profile within the statute limits. © 2012 Taylor and Francis Group, LLC.Item An effective reference generation scheme for DFIG with unbalanced grid voltage(Institute of Electrical and Electronics Engineers Inc., 2014) Asha Rani, M.A.; Nagamani, C.; Saravana Ilango, G.; Karthikeyan, A.This paper presents a reference current generation scheme for improved dynamic performance of a doubly fed induction generator (DFIG) subjected to unbalanced grid voltage. The power and torque oscillations induced due to the unbalance in grid voltage are minimized using additional compensatory terms in the reference currents. The focus is on estimating the reference currents and control implementation without the need for dual vector control. Real and reactive power control is implemented in the positive mbi d - q reference frame using stator flux-oriented vector control. The rotor-side converter (RSC) is controlled to enable effective reduction of oscillations in torque and active and reactive power. The dc-link voltage oscillation is minimized and the grid-side power factor is maintained unity using the grid-side converter (GSC). Unlike the previously reported techniques, the proposed scheme enables effective reduction of oscillations in torque, active, and reactive power, and the dc-link voltage, all in a single target. The performance of DFIG is investigated in consideration with the Indian Electricity Grid Code (IEGC). Numerical simulations are carried out in power system computer aided design/ electromagnetic transients including direct current (PSCAD/EMTDC) for the laboratory 3-hp DFIG test setup. The results establish that the performance of DFIG is notably enhanced with the proposed scheme. © 2014 IEEE.Item An adaptive reactive power perturbation based hybrid islanding detection method for distributed generation systems(Acta Press journals@actapress.com, 2016) Krishnan, G.; Gaonkar, D.N.The intentional islanding operation of distributed generation (DG) systems can bring many benefits to the DG owner, distribution network operators and customers. One of the requirements for intentional islanding operation is the successful detection of the grid events which can lead to islanding of the DG system. This paper presents the hybrid islanding detection method based on adaptive reactive power variation with a passive algorithm that relies on the transient response characteristics for facilitating islanding detection. The proposed method presented in this paper can overcome the problems in the reactive power variation based methods. Extensive studies are conducted for differentiating the transient characteristic features for islanded and non-islanded systems. In this study the adaptive reactive power sequence is modified to enhance the performance under sudden load changes. The proposed method proved to detect all probable islanding situations with minimum run-on time. The performance of the method is evaluated using simulation results obtained from MATLAB/SIMPOWERSYSTEMS software considering wind power based DG system.Item Fuzzy logic approach for reactive power coordination in grid connected wind farms to improve steady state voltage stability(Institution of Engineering and Technology journals@theiet.org, 2017) Moger, T.; Dhadbanjan, T.This study presents a fuzzy logic approach for reactive power coordination in grid connected wind farms with different types of wind generator units to improve steady state voltage stability of power systems. The load bus voltage deviation is minimised by changing the reactive power controllers according to their sensitivity using fuzzy set theory. The proposed approach uses only few controllers of high sensitivity to achieve the desired objectives. The 297-bus and 417-bus equivalent grid connected wind systems are considered to present the simulation results. To prove the effectiveness of the proposed approach, a comparative analysis is carried out with the conventional linear programming based reactive power optimisation technique. Results demonstrated that the proposed approach is more effective in improving the system performance as compared with the conventional existing technique. © 2016 The Institution of Engineering and Technology.Item Impact of Different PQ Models of Wind Turbine Generating Units (WTGUs) on System Voltage Performance(Walter de Gruyter GmbH info@degruyter.com, 2017) Moger, T.; Dhadbanjan, T.This paper presents the voltage performance analysis of the system with various types of wind turbine generating units (WTGUs). A detailed voltage performance analysis is carried out by considering the different PQ models used for computing the reactive power output of the WTGUs (fixed/semi-variable speed and variable speed WTGUs). The different PQ models of fixed/semi-variable speed WTGUs incorporated for the studies are voltage dependent model, voltage independent model, power factor based model, and PX model. In addition, the variable speed WTGUs are also considered in different fixed power factor mode of operation. Based on these models, a comparative analysis is presented. A modified 27-bus equivalent distribution test system with dispersed wind generation is considered for the studies. Further, the case studies have been carried out by considering the various wind power output levels of WTGUs to examine its impact on system voltage performance. From the comparative analysis, the power factor based model can be the best choice over the other models (which are based on voltages) for the system studies with fixed/semi-variable speed WTGUs. © 2017 Walter de Gruyter GmbH, Berlin/Boston 2017.Item Inrush Current Parameters Associated with Back-to-Back Switching of Capacitors in a Bank(Taylor and Francis Inc. 325 Chestnut St, Suite 800 Philadelphia PA 19106, 2017) Ramesh, M.; Nagamani, H.N.; Vaidhyanathan, V.; Punekar, G.S.Back-to-back switching of 50 kVAr capacitors, in a capacitor bank of 200 kVAr is investigated experimentally. The switching inrush currents in a three-phase, 200 kVAr, 415 V Automatic Power Factor Correction panel at power frequency are captured in the laboratory. The characterizing features of inrush current are reported and analyzed. The commercially available two makes of switches (contactors) are used to compare the inrush currents with and without their pre-insertion resistors (PIR). The inrush current scenario of the experimental setup is modeled in EMTDC/PSCAD to ascertain the results. The ratio Ipeak/IN for both the contactors without PIR exceeded the limit mentioned in IEC 60831-1 Ed 3.0 : 2014. © 2017, Copyright © Taylor & Francis Group, LLC.Item Evaluation of Reactive Power Support and Loss Allocation in a Pool Based Competitive Electricity Market(Walter de Gruyter GmbH info@degruyter.com, 2017) Moger, T.; Dhadbanjan, T.This paper presents a new approach using modified Y-bus matrix to compute the reactive power support and loss allocation in a pool based competitive electricity market. The inherent characteristic of the reactive power in system operation is properly addressed in the paper. A detailed case study on a 11-bus equivalent system is carried out to illustrate the effectiveness of the proposed approach. It is also tested on a large 259-bus equivalent system of Indian western region power grid. A comparison is also made with other existing approaches in the literature to highlight the features of the proposed approach. Simulation results show that the reactive power support and loss allocation from the proposed approach is carried out in a systematic manner which takes into consideration the power demand and the relative location of the nodes in the network. © 2017 Walter de Gruyter GmbH, Berlin/Boston.Item Critical review of PV grid-tied inverters(MDPI AG indexing@mdpi.com Postfach Basel CH-4005, 2019) Kavya Santhoshi, B.K.; Mohanasundaram, K.M.; Padmanaban, S.; Holm-Nielsen, J.B.; Koothu Kesavan, K.K.Solar Photovoltaic (PV) systems have been in use predominantly since the last decade. Inverter fed PV grid topologies are being used prominently to meet power requirements and to insert renewable forms of energy into power grids. At present, coping with growing electricity demands is a major challenge. This paper presents a detailed review of topological advancements in PV-Grid Tied Inverters along with the advantages, disadvantages and main features of each. The different types of inverters used in the literature in this context are presented. Reactive power is one of the ancillary services provided by PV. It is recommended that reactive power from the inverter to grid be injected for reactive power compensation in localized networks. This practice is being implemented in many countries, and researchers have been trying to find an optimal way of injecting reactive power into grids considering grid codes and requirements. Keeping in mind the importance of grid codes and standards, a review of grid integration, the popular configurations available in literature, Synchronization methods and standards is presented, citing the key features of each kind. For successful integration with a grid, coordination between the support devices used for reactive power compensation and their optimal reactive power capacity is important for stability in grid power. Hence, the most important and recommended intelligent algorithms for the optimization and proper coordination are peer reviewed and presented. Thus, an overview of Solar PV energy-fed inverters connected to the grid is presented in this paper, which can serve as a guide for researchers and policymakers. © 2019 by the authors.