Journal Articles
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Item Reconfiguration strategies for reducing partial shading effects in photovoltaic arrays: State of the art(Elsevier Ltd, 2019) Sai Krishna, G.; Moger, T.Power delivered by a Photovoltaic (PV) cell reduces significantly due to non-uniform irradiance. Consequently, in the case of PV module or array, the generated output power get reduces and further deteriorates the overall system performance. The reduction of output power is not directly proportional to the shading area but depends on the shading pattern and type of array configuration chosen. Many solutions have been reported in the literature to reduce partial shadings. However, the reported solutions may fail to enhance maximum power to the possible extent. Therefore, to compensate these power losses a promising technique is required which relies on reconfiguration strategies, namely reconfigure the PV modules within the PV array in order to increase maximum power at a higher level. These strategies are classified into dynamic and static reconfiguration techniques. This paper presents the state of the art of reconfiguration strategies for PV array's to increase maximum power under partial shading and mismatch conditions. In addition to this, the challenging issues for hardware implementation of both dynamic and static reconfiguration techniques are discussed in this paper. Based on the review study, it can be concluded that the dynamic reconfiguration techniques are relatively expensive, but this can effectively compensate the partial shading and mismatch effects in PV array as compared to static technique. © 2019 International Solar Energy SocietyItem 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 LtdItem Uncertainty handling techniques in power systems: A critical review(Elsevier Ltd, 2022) Singh, V.; Moger, T.; Jena, D.Integration of renewable generations with electrical power systems has gained considerable attention in recent years due to environmental and economic benefits. However, this integration introduces additional uncertainties into the existing system and requires appropriate uncertainty modeling for power systems. Typically the uncertainties in power systems are modeled using probabilistic or possibilistic approaches. A combined probabilistic-possibilistic approach is necessary when some uncertain variables are probabilistic and others are possibilistic. This paper presents a complete review of uncertainty categorization and several techniques to address the uncertainty in power systems, along with the merits and weaknesses of each technique. The challenges have been highlighted for future research directions. Analytical and approximate methods are reviewed in this paper when wind power generations are integrated into the existing power grid. Considering the uncertainties of wind power generation and system load demands, the basic probabilistic methods such as Monte-Carlo simulation, cumulant, and 2n+1 point estimation methods are implemented. To explore the capability and shortcoming of these basic methods, a 72-bus equivalent system of Indian southern region power grid is taken into consideration. The results obtained using Monte-Carlo simulation method are treated as a benchmark to analyze the performance of the cumulant and 2n+1 point estimation methods. © 2021 Elsevier B.V.Item A survey on load frequency control using reinforcement learning-based data-driven controller(Elsevier Ltd, 2024) Muduli, R.; Jena, D.; Moger, T.Load frequency control (LFC) is a significant control problem in the operation of interconnected power systems. It keeps the change in system frequency within specific limits by maintaining the balance between power generation and load demand. In modern interconnected power systems, various control strategies, including conventional control techniques and other data-driven approaches, have been adopted to improve the effectiveness of LFC. The control technique based on reinforcement learning (RL) is one of the contemporary data-driven control strategies for LFC. Recently, the attention of researchers has surged towards RL-based control strategies for LFC. Several survey literature has been published in the field of LFC concerning the various control strategies for the effective operation of the power system. However, these surveys have not considered a complete systematic review of RL-driven LFC. An exhaustive review is essential to demonstrate the current status and identify future advancements in this field. This paper presents a comprehensive review of LFC based on the RL-driven control strategy. This study begins by presenting a mathematical and conceptual understanding of reinforcement learning. Finally, a broad classification of RL algorithms and the algorithm-wise literature survey on LFC are provided extensively. This comprehensive and insightful literature survey may serve as a valuable resource for the researchers, addressing the gaps between recent advances, implementation difficulties, and future developments in LFC using the RL-driven control strategy. © 2024 Elsevier B.V.Item Advances in Composite Power System Reliability Assessment: Trends and Machine Learning Role(Institute of Electrical and Electronics Engineers Inc., 2025) Yarramsetty, C.; Moger, T.; Jena, D.; Rao, V.S.This paper provides a detailed review of reliability assessment methods for composite power systems, focusing on integrating renewable energy and advanced computational approaches. The study classifies existing research into three main areas: investigation studies, planning and optimization studies, and efficient evaluation studies. Findings indicate that machine learning techniques are increasingly important in improving accuracy and computational performance in reliability analysis. A comparative examination of conventional and Machine Learning (ML)-based methods demonstrates that deep learning models, such as Convolutional Neural Networks, offer substantial reductions in computational time while maintaining reliability assessment precision. The review also identifies key research gaps, such as the need for realistic test systems and enhanced hybrid ML strategies. Additionally, recommendations are proposed to address these challenges and strengthen the effectiveness of future reliability evaluation methodologies. The insights presented in this study aim to support researchers and industry professionals in developing more efficient and scalable reliability assessment models for evolving power systems. © 2013 IEEE.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 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 Improved SuDoKu reconfiguration technique for total-cross-tied PV array to enhance maximum power under partial shading conditions(Elsevier Ltd, 2019) Sai Krishna, G.; Moger, T.Mismatch losses ignore the performance of individual photovoltaic (PV) modules and cut back most of the power from the PV array. These losses mainly due to partial shading condition (PSC), are caused by the reduction of spacing between PV modules, passing clouds, and near buildings, etc. Several techniques are present in the literature to cut back the partial shading issues. One of the most effective methods is the reconfiguration techniques, namely reconfigure the location of PV modules in PV array so as to distribute partial shading effects and increase the maximum power output. This paper proposes an Improved SuDoKu reconfiguration pattern for 9×9 Total-Cross-Tied (TCT) PV array to enhance maximum power output under partial shading conditions. The main aim of this approach is to arrange the PV modules in TCT array according to the SuDoKu pattern without altering the electrical connections. Further, the performance of the proposed pattern is evaluated with different existing PV array configurations by comparing the Global Maximum Power Point (GMPP), Mismatch Losses (ML), Fill Factor (FF) and Efficiency (?). Based on the results of this paper, it is concluded that the proposed improved SuDoKu PV array arrangement enhances the global maximum power under all shading conditions. © 2019 Elsevier LtdItem Enhancement of maximum power output through reconfiguration techniques under non-uniform irradiance conditions(Elsevier Ltd, 2019) Sai Krishna, G.; Moger, T.Partial shading is one of the major drawback which diminishes the power output of the PV array. One of the effective methodologies is reconfiguration strategies, namely shifting the location of PV modules from one place to different places so as to distribute shading effects over the array to increase maximum power output under PSCs. This paper proposed two novel puzzle arrangements followed by Ken-Ken (KK) and Skyscraper (SS) for 4×4 total-cross-tied (TCT) PV array and increase maximum power under PSCs. In this approach, the PV modules in the TCT array is arranged according to Ken-Ken and Skyscraper arrangements without changing the electrical connections. Further, the performance of the proposed arrangements are investigated with different existing PV array configurations by comparing the global maximum power point (GMPP), the voltage at global maximum power point (VGMPP), mismatch losses (ML), fill-factor (FF), efficiency (?) and possible local peaks (PLP) under different shading patterns using Matlab-Simulink. An extensive simulation study is carried out on these configurations under different shading patterns as well as temperatures. Also, a comprehensive comparison has done for various reconfiguration schemes presented in literature. The result shows that the proposed arrangements are enhancing the global maximum power as compared to the other existing configurations. © 2019 Elsevier Ltd