Journal Articles
Permanent URI for this collectionhttps://idr.nitk.ac.in/handle/123456789/19884
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Item Seamless transfer of microturbine generation system operation between grid-connected and islanding modes(2009) Gaonkar, D.N.; Pillai, G.N.; Patel, R.N.The intentional islanding operation of grid-connected distributed generation systems can greatly improve the reliability and quality of the power supply. The existing control techniques for distributed generation systems are designed to operate either in the grid-connected or islanding modes of operation, thus, not allowing for both modes to be implemented and transitioned between. In this article, a novel scheme for automatic mode switching of a microturbine-based distributed generation system between the grid-connected and islanding modes of operation is proposed. The presented scheme is based on the phase angle estimated by the phase-locked loop. The developed phase-locked loop provides an accurate estimation of the phase angle even under unbalanced conditions. The presented scheme does not negatively affect the distributed generation system or utility operations and can work even under matching distributed generation and load power ratings. In this work, back-to-back converters are used to interface the microturbine-based distributed generation system to the grid. Converter control strategies developed for both modes of distributed generation operation is also presented. The simulation results show good accuracy of the proposed scheme.Item Investigation on electromagnetic transients of distributed generation systems in the microgrid(2010) Gaonkar, D.N.The increasing interconnection of distributed generation sources of diverse technologies to low-voltage grids introduces considerable complexity in its operation and control. The concept of the microgrid is emerging as a solution to this and also to take full advantage of the potential offered by distributed generation. In this article, the performance of a typical microgrid with multiple distributed generation systems in grid-connected and autonomous modes of operation has been investigated through simulation. The developed model of the microgrid consists of a converter-interfaced microturbine generation system, a synchronous-generator-based distributed generation system, and a wind power generation system with an asynchronous generator. Investigation has been carried out to study the typical electromagnetic transients of a microgrid, due to preplanned and unplanned switching events. The performance of the bidirectional grid interface topology for a microturbine generation system in a microgrid is evaluated in this work. It has been observed from the simulation results that the motoring mode operation of the microturbine generation system during starting does not cause any disturbances in the microgrid. The study also indicates that the microgrid can maintain the desired power quality at the point of common coupling. Copyright © Taylor & Francis Group, LLC.Item Coordinated voltage control using multiple regulators in distribution system with distributed generators(2011) Shivarudraswamy, R.; Gaonkar, D.N.The continued interest in the use of distributed generation in recent years is leading to the growth in number of distributed generators connected to distribution networks. Steady state voltage rise resulting from the connection of these generators can be a major obstacle to their connection at lower voltage levels. The present electric distribution network is designed to keep the customer voltage within tolerance limit. This may require a reduction in connectable generation capacity, under utilization of appropriate generation sites. Thus distribution network operators need a proper voltage regulation method to allow the significant integration of distributed generation systems to existing network. In this work a voltage rise problem in a typical distribution system has been studied. A method for voltage regulation of distribution system with multiple DG system by coordinated operation distributed generator, capacitor and OLTC has been developed. A sensitivity based analysis has been carried out to determine the priority for individual generators in multiple DG environment. The effectiveness of the developed method has been evaluated under various cases through simulation results.Item Coordinated voltage control using multiple regulators in distribution system with distributed generators(2011) Shivarudraswamy, R.; Gaonkar, D.N.The continued interest in the use of distributed generation in recent years is leading to the growth in number of distributed generators connected to distribution networks. Steady state voltage rise resulting from the connection of these generators can be a major obstacle to their connection at lower voltage levels. The present electric distribution network is designed to keep the customer voltage within tolerance limit. This may require a reduction in connectable generation capacity, under utilization of appropriate generation sites. Thus distribution network operators need a proper voltage regulation method to allow the significant integration of distributed generation systems to existing network. In this work a voltage rise problem in a typical distribution system has been studied. A method for voltage regulation of distribution system with multiple DG system by coordinated operation distributed generator, capacitor and OLTC has been developed. A sensitivity based analysis has been carried out to determine the priority for individual generators in multiple DG environment. The effectiveness of the developed method has been evaluated under various cases through simulation results.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 Performance analysis of a variable-speed wind and fuel cell-based hybrid distributed generation system in grid-connected mode of operation(Taylor and Francis Inc. 325 Chestnut St, Suite 800 Philadelphia PA 19106, 2016) Ayyappa, S.K.; Gaonkar, D.N.This article presents the performance study of a variable-speed wind and solid oxide fuel cell-based hybrid distributed generation system, along with the energy storage devices in the grid connected mode of operation. The developed model has a salient feature of utilizing fluctuating output power of wind systems to produce hydrogen and also to charge the ultra capacitor. The presented model in the article also uses the stored energy in the ultra capacitor to compensate for the slow response time of the fuel cell. The distributed generation systems and energy storage devices considered in this study are integrated at common distributed generation links to form the hybrid system. The hybrid system is interfaced to the grid through the three-phase voltage source inverter in this article. The detailed modeling of the individual components of the hybrid distributed generation system, along with the necessary power electronic converter control schemes, are presented. The simulation results reported in this article show the effective performance of the hybrid model to produce reliable, low-cost electricity and hydrogen from the variable wind generation system. © 2016 Taylor & Francis Group, LLC.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 Investigation of Power losses on Solar Photovoltaic Array Interconnections Under Mismatch Conditions(Springer, 2021) Sai Krishna, G.; Moger, T.The mismatch effect creates a difference between the sum of maximum power generated by individual Photovoltaic (PV) modules and the overall PV array power output. Mismatch effects can be classified into internal and external mismatch effects. Internal mismatch effect occurs because of factors such as manufacturing defects and ageing. The external effect occurs because of variations in solar irradiance and temperature. This paper presents the investigation of internal and external mismatch effects on various 5×4 Photovoltaic (PV) array interconnections such as series-parallel, total-cross-tied, bridge-link, honey-comb, hybrid SP-TCT, hybrid BL-TCT, along with proposed hybrid HC-TCT and hybrid HC-BL. Six mismatch case studies are considered in this paper to investigate the performance of PV array connections. Among the six cases, three cases are due to internal mismatch effects, and the remaining three cases belong to the external effects. In addition, the global maximum power point (GMPP), the voltage at GMPP, thermal voltage, power loss, fill-factor, efficiency (?), and possible local peaks (PLP) parameters are calculated and compared for each PV array connection under all case studies using Matlab-Simulink. Also, for each PV array connection, the revenue generation is calculated from energy savings under mismatch effects. The paper summary shows that TCT, HC-TCT, and HC-BL array connections delivered beneficial results under external effects, and TCT, HC, HC-TCT, and HC-BL provided superior results under internal effects. © 2021, The Author(s), under exclusive licence to Springer Nature Singapore Pte Ltd.