The geometrical accuracy of the hydro turbine runners is one of the most critical contributors to turbine performance, reliability, and eventually to the capacity utilization throughout its service life. However, achieving a high degree of accuracy in the runners of small hydro plants is challenging with conventional methods, due to their size limitations. This paper investigates the impact of the manufacturing of runners of small hydro plants using conventional casting methods on their performance. To address the limitation posed by the conventional method, the application of novel hybrid technology is explored, employing both additive and casting technology. The impact of both the conventional and the proposed hybrid technologies is compared through Computational Fluid Dynamics (CFD) analysis and experimental study. The test result with the conventional casting method shows approximately a 14

The power density of electrical machines has increased significantly over the last century due to tremendous advancements in material science, particularly in the electrical insulation systems (EIS) domain. However, both industry and academia have limited experience with the design and production of electrical machines operating at winding temperatures above 240°C, owing to the application threshold temperature of EISs and other challenges associated with design, manufacturing, and testing. This article examines the key considerations for addressing these challenges and surpassing the prevailing threshold temperature. The design approach for these specialized machines, capable of continuous operation at 350°C, is presented. Additionally, the impact of temperature on various motor performance metrics is examined using finite element analysis (FEA) and further validated through an experimental study. Surpassing the temperature rise limit of conventional polymer-based EIS will enable higher power density, thereby reducing the consumption of critical and precious materials and helping the motor industry better align with green manufacturing initiatives. Furthermore, as components and systems related to the cooling circuit become redundant, system reliability and availability will improve, which is essential for the nuclear, aerospace, medical, and transportation industries.

Centrifugal pumps are an inseparable part of the sustainable life of the population across geographies, agriculture, energy, and all industrial sectors. Hence, pumps and their drives account for a significant portion of global energy consumption, and improving their energy efficiency is critical for sustainability and energy security. One approach to optimizing energy consumption is variable-speed operation of the driving motor with variable-frequency drives (VFDs), rather than the traditional method of throttling the pump valve, which wastes much of the energy when system demand fluctuates. However, deployment of this approach remains limited in scale, especially in non-industrial applications, due to a lack of full understanding of its technical and economic aspects. In the present paper, the impacts on various performance parameters of an 18.5 kW, 4-pole induction motor have been studied under variable-speed operation using Finite Element Analysis (FEA). The deviations in various performance parameters from the theoretical estimates are quantified, and their impact on pump operation is explored. The economic and environmental analyses showed that variable-speed control of the considered machine has an annual energy-saving potential of 35,400 kWh and a potential reduction in carbon emissions of 30.5 tons.

Polyimide insulation materials have emerged as critical components in high-performance motor designs for nuclear and other critical applications. Their exceptional thermal, electrical, and mechanical properties make them ideal for environments where reliability under extreme conditions is paramount. However, in many cases, the projects undergo a long gestation period (e.g., nuclear power plants), and hence, electrical machines often endure long pre-commissioning storage. However, though the accelerated thermal aging effects on electrical insulation materials are well established, studies specifically addressing the ambient temperature storage effects on those are limited. This paper investigates the effects of such long-term storage of an electrical insulation material frequently used in nuclear, aerospace, defense, and other critical applications, i.e., Polyimide (PI) film heat bonded with Fluorinated Ethylene Propylene (FEP), at ambient temperature. Insulated conductors were stored for seven years at an ambient temperature varying between 15-30 degrees C and at a relative humidity between 40-70%. The samples were tested before and after storage to assess the changes in electrical and mechanical properties. The residual operation life was also compared by performing accelerated thermal aging tests according to IEC 60172. Substantial degradation in the mechanical and electrical properties was observed even in the low-temperature aging process, however, any reduction in the residual life was not revealed.

The rotor eccentricity fault is one of the weak links in the reliability chain of induction motors (IM), and the commercially available solutions for its detection are complex, costly, and, most importantly, require service interruption. Therefore, in real-world scenarios, measurements of rotor eccentricity are not common unless its effects become noticeable through increased noise, vibrations, or bearing failure. However, such practices exacerbate the severity of faults and can lead to catastrophic and cascading failures. In this work, the effects of various eccentricity faults are discussed in detail, and a search coil-based solution is explored for online detection of rotor eccentricity events without interrupting machine operation. The proposed method is based on the principle of induced voltage compensation, utilizing coils placed near the air gap to achieve better accuracy. Finite element analysis demonstrates that this technique not only quantifies the extent of eccentricity with reasonable precision but is also capable of generating metadata such as the type of eccentricity and residual bearing life. The effectiveness of the fault detection method is verified through experiments with different configurations of search coils, demonstrating their ability to identify bearing abnormalities and eccentricity faults early, proving its potential to prevent catastrophic failures, especially in critical applications such as nuclear power, chemical, aerospace, and defense.

Induction motors (IM) are more economical, robust, and reliable compared to rare-earth-based machines and hence continue to dominate the market share, especially for industrial applications. However, the rotor eccentricity fault is one of the weak links in the IM reliability chain. This paper presents a detailed magnetic field transient analysis of canned induction motors for simulating static and dynamic eccentricity faults. In the present work, a detailed FEA study was carried out to investigate the effect of rotor eccentricity on important performance parameters of an induction motor such as torque, current, and air gap flux density. The effect of increasing eccentricity on the unbalanced magnetic pull is also studied for static and dynamic eccentricity.

The progress in material science, especially in polymer technology has enabled continual increase in power density of electrical machines over the last century. However, this continual improvement has been halted by the thermal application limit of polyimide, i.e., 240 °C. And hence the experience of industry in design and manufacturing of electrical machines beyond this temperature is very limited. Motors suitable for continuous operation at higher temperature will enable increase in power density in one hand, and enable elimination of several components and sub-systems (e.g., motor cooler, heat exchangers) on the other. Hence the reliability of the machines can be improved which is very crucial for special applications such as in canned motor pumps in nuclear reactor cooling application, surface transportation, and aeronautical applications. In the present work a detailed FEA study was carried outto investigate the impact of temperature rise on different performance parameters of an induction motor for a canned motor pump application.

The present research explores transmission congestion control in Battery based Energy Storage Systems (BESS) integrated grids using Optimal Transmission Switching (OTS). The oversimplification of underlying assumptions in prior OTS-based congestion management strategies leads to excessive line switching which is undesirable. Hence, a novel reliability constrained alternating current optimal power flow (AC-OPF) based OTS is presented to mitigate the line congestion in the BESS integrated grids. The suggested approach is solved to acquire the OTS solution for 24 h time frame with the primary goal of minimising generating costs subjected to ac power flow equality, BESS, reliability, and transmission congestion constraints. The proposed approach makes use of the integer variable to represent the transmission switching operations and is solved by using a mixed-integer non-linear programming (MINLP) solver. The inclusion of reliability constraints ensures the system reliability by limiting the value of load failure probability to a pre-specified limit. The feasibility of this approach is validated by testing it on a standard IEEE test system for various loading scenarios. The results exhibit that coordinated charging/discharging of BESS supports reducing the number of lines switchings required for congestion management compared to the existing approaches, substantially.

The power density of electrical machines has increased manifold over the last century due to the immense progress made in material science, especially in the domain of electrical insulation systems (EIS). However, the experience of the industry, as well as academia, is very limited regarding the design and production of electrical machines with winding temperature rise beyond 240 degrees C due to the application threshold temperature of EISs. The present article discusses the design considerations for transcending this boundary imposed by the conventional polymerbased EIS. The rationale behind the choice of different materials suitable for continuous operation at 350 degrees C is discussed. The effect of temperature on different motor performances is also investigated. Breaking the ceiling of the temperature rise limit of the conventional polymer-based EIS will allow the use of higher current/power density and thereby reduce the consumption of critical and precious materials, thereby not only increase the system reliability which is crucial for nuclear, aerospace, medical, and transportation industries but also help the motor industry align better with green manufacturing practices.

Partial shading condition (PSC) poses a significant challenge to solar power generation as it has a severe impact on the performance of photovoltaic (PV) systems, leading to a decrease in energy yield and reliability. Recon-figuration of PV arrays is a potential technique to deal with this challenge, however, reconfiguration techniques proposed in the past are restricted in their suitability for practical implementations in real-world installations as they are only optimal for specific shading patterns. To overcome this limitation, the article introduces a novel reconfiguration approach inspired by the circular array data structure, a commonly utilized tool in the realm of computer science. The proposed circular array transformation (CAT) technique shows great potential in miti-gating the impact of partial shading (PS) and maximizing the overall power generation across a wider range of PSCs. The effectiveness of the proposed technique is validated through simulations and experimental studies conducted on a 5 x 5 PV array. Furthermore, the scalability of the proposed reconfiguration technique is verified through extensive simulations on a 9 x 9 PV array. Comparative analysis reveals that the proposed CAT rear-rangement approach exhibits clear dominance and outperforms existing and recently published state-of-the-art reconfiguration methods.

Generation of the hot spot in photovoltaic cells (PV) cells under partial shading conditions (PSC) is a persistent issue associated with PV systems which not only affects the PV performance but also increases the cell temperature (up to 400 degrees C in extreme cases), and thereby causes premature failure. This article presents a novel technique to prevent the reverse breakdown and thereby mitigate the hot spot tem-perature of the PV cells under partial shading by reducing reverse current through automated reconfi-guration of PV array. The efficacy of the proposed technique is evaluated by simulating eight different shading scenarios, under which the reconfiguration algorithm automatically switched different PV configurations based on the nature of the shading pattern. The performance of the PV arrays is evaluated using IGBT as the switching device, and the performance is compared with an ideal switch-based circuit. The proposed technique is found to reduce the reverse voltage and reverse current and through the affected modules and thereby increase the reliability index in 82% of the cases. Hence the proposed reconfiguration algorithm is expected to increase the PV reliability and thereby increase the performance ratio of the PV projects, especially which are susceptible to frequent partial shading conditions. (c) 2021 Elsevier Ltd. All rights reserved.

This article presents a novel methodology for distribution network expansion planning (DNEP) considering the inclusion of electric vehicles (EVs), especially, electric bus (EB) charging loads. The proposed methodology addresses network congestion through an optimum time of charging, cost optimization, new charging infrastructure, and minimization of losses under a set of technical and physical constraints, which represents practical uncertainties. Along with load flow analysis, selection of the number of ports and technology at the host charging station is obtained through the application of response surface methodology. The proposed methodology provides coordinated planning for the development of EB charging station infrastructure that takes into account the effects of both the power dispersion framework and transportation framework. The effectiveness of the proposed methodology is investigated by applying it to the 69-node IEEE modified distribution test system considering three charging technologies, viz. fast charging, ultra-fast charging, and battery swapping. The results of the proposed model are compared with the direct statistical method, and it revealed that the right selection of technology for EB charging and the right planning of the charging infrastructure can effectively optimize the cost of EV charging infrastructure and thereby catalyze the decarbonization of the transportation sector.

Abstract To participate in the global fight against climate change, India has set an aggressive target of installing 100 GW of photovoltaic (PV) energy resources by 2022. However, only about 37% of this target is achieved till date, and, presently, the set target appears to be elusive. Hence it is crucial and the need of the hour to analyze the performance of different utilities to identify the regions that need a course correction. In the present work, the relative performance of the Indian states in realizing the national target of PV installed capacity is analyzed through the Data Envelopment Analysis (DEA) model. Time series analysis of the PV sector’s growth in different Indian states over the period 2017–2021 is quantified through the Malmquist productivity index (MPI). The applied methodology revealed that Rajasthan, which has the highest PV potential and second-highest PV installed capacity, is less productive than the small hilly states and union territories, which have meager PV potential. The result provides insight into the factors contributing to the inefficiencies in the development of the PV energy sector, which will help the policymakers take necessary corrective actions to improve the states’ productivity and thereby contribute more effectively to the national goal. The work may be extended to other regions of the world to strengthen the global effort to fight climate change.

Non-uniform irradiation levels also have a negative impact on solar photovoltaic (PV) systems, forcing them to increase their power losses. Each PV array row has different current generation levels due to the effect of partial shading conditions (PSCs) and eventually has multiple power maxima, e.g. global maximum power point (GMPP) and local maximum power point (LMPP) on the power-voltage (P-V) characteristics. The presence of multiple power maxima as a result of non-uniform irradiances always causes the maximum power point tracking (MPPT) device to be mislead. To address the aforementioned issue, the reconfiguration scheme depicts the physical relocation as well as the unaltered electrical connections in the PV array. In this context, a new physical relo-cation alternative solution based on the Ancient Chinese MagicSquare (ACMS) puzzle demonstrates efficient behavior under PSCs. The results show that the ACMS based reconfiguration offers higher shade dispersion over the entire PV array system relative to the existing total-cross tied (TCT), Su-do-Ku, and consequently decreases the power mismatch loss and GMPP locations through P-V characteristics observation. In the MATLAB/Simulink study, power values at GMPP are observed for the ACMS based configuration as 324.9 W, 340.9 W, 327.6 W, and 382.5 W under all four shading scenarios. Real-time experimental study of 9 x 9 size PV array configurations demonstrates and validates the higher side performance of the proposed reconfiguration approach under the considered shading scenario.

The world has resorted to photovoltaic (PV) technologies to alleviate the broad spectrum of issues posed by fossil fuel-based energy generation, and presently global cumulative PV capacity has crossed over 650 GW. However, PV technology has some inherent challenges which need to be addressed for effective and efficient utilization. Partial shading condition (PSC) is one of those, which does not only diminish the peak power output but also causes hot spotting and irreversible damage of PV cells in some cases. In the present work, the comparative performance of different PV topologies is studied, under various PSCs simulated in MATLAB®/Simulink platform.

Presently, the world is going through a euphoric rush to install photovoltaic (PV) devices in deserts, over water bodies, on rooftops of houses, vehicles, and parking spaces, and many other applications. The cumulative PV installation is estimated to have crossed 600 GW globally to date and is expected to cross 4500 GW by 2050 due to sustained investment and continual innovation in technology, project financing, and execution. This article presents a critical and comprehensive review of the wide spectrum of present and future PV technologies, not only in terms of their performance but also in terms of the aspects of their end-of-life waste management and ecotoxicity, which have been largely neglected by the researchers and policymakers. The global status of the regulatory framework is reviewed as well, with regard to the life cycle management of PV waste. And It is found that presently, the world is very poorly equipped with regulatory frameworks to deal with massive PV waste (about 78 million tonnes), expected to be generated by 2050. Based on the findings, an immediate and disruptive paradigm shift is proposed in the policy framework, from the promotion of new PV installation to life cycle management of PV assets.

The accumulated financial loss of the Indian state-owned electricity utilities (SOEUs) has crossed over USD 6.25 billion and 80% of the SOEUs are consistently incurring losses and hence financially unsustainable in long term. In this article, the impact of three decades of Indian policy reform towards reviving the techno-commercial performance of the SOEUs is critically assessed. To quantify the relative performance of SOEUs and bring out the reason behind the inefficiencies of individual SOEUs, data envelopment analysis improved by Shannon's entropy model is applied. The benchmark SOEUs are identified for each inefficient ones, and corrective policy measures are recommended.

48The world has found the solution to the problem of finding a trade-off between the ever-increasing demand of energy and greenhouse gas emission thereof, in photovoltaic (PV) technology. PV technology has alleviated a plethora of issues associated with conventional fossil fuel-based energy generation and, hence, presently global cumulative PV installed capacity has increased to over 650 GW. However, it has several concomitant technological challenges associated with it as well, which need to be addressed for its effective utilization and reliable operation, such as partial shading condition (PSC). PSC does not only cause mismatch power loss and thereby reduce the peak power output, it also generates hotspot, which eventually causes irreversible damage to the PV cells in most of the cases. In the present work, comparative performance of different PV array topologies (series-parallel, bridge-link, and total-cross-tied) are experimentally investigated, under different simulated PSCs. The result of the study reveals that innovative array topologies may be one of the promising solutions to the PSC problems associated with PV technology.

For expansion of any country's economy, development of infrastructure, and eventually improving the quality of life, electrical power is one of the greatest enabler. And hence three decades back, India, initiated power sector reforms to make its power sector efficient and sustainable. However, even three decades after starting the reform initiatives, almost all the state power utilities are under significant financial and technical losses, which is hindering further expansion and strengthening of distribution system. This paper analyses the present scenario of Indian power distribution sector and the reasons behind it's poor financial and technical performance. Through the comprehensive analysis, it is shown that even after introduction of new policies, reforms, and regulatory initiatives, Indian distribution sector is still suffering from systemic flaws and vulnerabilities characterized by cross-subsidies, inefficiency, substantial technical and financial losses, poor quality of power, low efficiency, outstanding debts, frequent supply disruptions, inability of expansion, sluggish privatization, poor customer satisfaction, political interference, and low reliability. This paper discusses the chronology of reforms brought in so far in the power distribution sector in India, and further suggests measures that can be adopted in administrative, technical, and commercial fields to improve the quality and reliability of supplied power.

Data envelopment analysis (DEA) model was introduced nearly half a century ago for evaluation of relative efficiency of entities having homogeneous set of input and outputs. Classical DEA has been applied to wide and diverse fields of research since its inception, due to its applicability to universal problems without any prior knowledge of functions of entities understudy or the interrelation between the inputs and outputs. However, it has certain shortcomings and several extensions of the basic DEA model have been introduced in the literature. This paper discusses the basic concept of the classical DEA models, its advantage and disadvantages vis-à-vis more recent extensions of this model.