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Use of distributed generators in distribution networks is proved highly reliable and economical. In utility practice at the present time, accidental islanding is an undesirable mode of operation as it can harm the personnel and other connected systems. Therefore, islanding must be detected and the islanded distributed generators must be disconnected from the rest of the system. This paper proposes a new islanding detection method which provides a reliable detection in two levels. At first level wavelet energy entropy is used as an indicator to suspect islanding and activate second level method. Second level method is an active frequency drift method with positive feedback and pulsating chopping fraction that vary the output voltage frequency of distributed generators to realize the anti islanding protections. The performance of the proposed method is simulated in MATLAB environment. The proposed algorithm provides fast islanding detection with least disturbance in inverter’s grid connected operation. [ABSTRACT FROM AUTHOR]

Multilevel inverters (MLIs) have been developed to a matured level for generating high quality output voltage, used in numerous applications. Conventional MLIs has been received more attention due to their remarkable use in medium-voltage applications. But use of high number of part counts in conventional MLIs increase the intricacy of circuitry and controlling both results in high expenses and reduced reliability. Therefore, development of newer topologies is an active attention to reduce part count compared to the conventional MLIs. This paper presents an exhaustive review of recently proposed reduced part count MLIs for grid integration application on the basis of selection of components, comparative factors and their suitability. It is aimed at presenting a state of the art on configuration, working and their features to researchers, inventors, and application engineers dealing with multilevel inverters. [ABSTRACT FROM AUTHOR]

The linear switched reluctance motor (LSRM) has emerged to be the most promising alternative due to the development of power controllers in the past years. In this paper, a novel configuration of LSRM with an active-stator-passive-translator is proposed for the traction propulsion system. It comprises a short active stator retrofitted with the transit mover, while a long stationary translator is considered as rail guidance of the system. In this paper, high grade M-19 cold-rolled non-oriented steel is utilized for manufacturing the stator and translator cores. The proposed configuration of electric locomotive makes use of force generated from linear switched reluctance motors to propel it on parallel rails and pushes the coaches attached to the wagon for carrying the functional load. Finally, the motor characterization is performed in ANSYS electromagnetic simulation tool, to determine the applied forces, coupling inductance, and strength of magnetic field of the proposed LSRM for the traction propulsion system. Thus, the experimental evaluation is carried out for various parameters to depict the sustainability and suitability of the LSRM for high-speed transition system. Proposed configuration of electric traction system [Display omitted] [ABSTRACT FROM AUTHOR]

The tourism industry has adopted AI agents as substitutes for human contact. We examine how tourists respond to AI in hotel service settings during a pandemic. Four studies show that services featuring human interaction is preferred to AI enabled interaction. Moreover, subjective happiness is identified as the underlying causal mechanism that drives this effect. We provide further nuanced insights by showing that politically conservative tourists discriminate between service agent types more. Theoretically we contribute to a more fine-grained understanding of tourists' responses towards AI by examining an affective and an individual difference factor (political ideology). Practically, marketers are encouraged to incorporate tourists' ideologies and psychographics into segmentation, targeting, and positioning considerations, thereby enhancing their marketing effectiveness. • The tourism industry has adopted AI-enabled agents as substitutes for human contact. • Subjective happiness drives favorable responses towards human services. • Politically conservative tourists discriminate between service agent types. • For conservatives, human interaction remains a preferred touchpoint in services. [ABSTRACT FROM AUTHOR]

Wind energy conversion system (WECS) is interfaced with the utility system through power electronic converters which plays an important role in the integration of wind power into the electric grid. The main power quality disturbances due to integration of WECS to grid are variation in power and harmonics. To maintain grid synchronization and to keep total harmonic distortion (THD) within operational limits, appropriate control schemes are required for the grid side converter. The main objective of grid side controller is to control the power delivered to the grid, grid synchronization, to supply high quality power to grid and to meet grid code compliance. In this paper control schemes used in grid interfaced wind energy conversion system for generator side and grid side converter control, are reviewed thoroughly. The paper presents a comparative study of rotor flux oriented control and direct torque control (DTC) techniques applied in generator side converter of permanent magnet synchronous generator (PMSG) drives for wind turbine application. For grid side converter, various control schemes are developed mainly based on voltage oriented control (VOC) or on direct power control (DPC). The performance of VOC based control system basically depends on method applied for current control. A comparative study is done among them and findings are tabulated. Integration requirements of wind turbine to grid, grid synchronization and requirement of monitoring unit are also discussed. [ABSTRACT FROM AUTHOR]

Abstract: In recent decades, factors such as the worldwide growing concern for pollution induced climate changes, increasingly stringent emission norms for vehicles and depleting petroleum resources coupled with volatility in their prices have motivated and accelerated development of sustainable and clean alternatives for transportation systems. Electrification of vehicular technology (EVT) is considered as a promising and sustainable alternative for future transportation systems. In evolution of EVT, instability of fuel price, fuel economy, range, performance and costs are the governing factors and prime concerns for researchers, auto manufacturers and customers. These factors are decided by the design of the electric propulsion system (EPS) for vehicular application and its suitable integration with various electrical and mechanical components. In this paper, a comparative overview of EVT along with a comprehensive analysis of EPS and a brief discussion on power flow control and management algorithms for EVT is presented. The paper also highlights the ongoing technological advancements and future challenges in the roadmap of EPS for the electrification of vehicular technology. [Copyright &y& Elsevier]

Abstract: Suitable integration of more than one energy sources is an interesting and challenging task that attracts attention of the researchers. Integration of several energy sources profoundly depends on the power electronic converters which interface multiple energy sources having different V–I characteristics. Therefore, suitable integration and better utilization of energy source demands, well designed and efficient interfacing circuitry. In this paper, a non isolated multiple source DC/DC converter (MSC) is proposed. The generation of MSC using pulsating source cells as a building block has been discussed briefly. The proposed converter is proficient for energy diversification from renewable and storage energy sources individually or simultaneously. It has the capability to operate either in buck, boost or buck–boost mode of operation with possibility of bidirectional power flow. It offers simplicity in structure with inherent bypass circuit, flexibility in control scheme and reliability in operation. In addition, a power management control algorithm for proposed converter has also been discussed. The proposed concept has been investigated through detailed device level simulation using MATLAB/Simulink environment. Experimental implementation and validation have been carried out on a low power prototype using digital signal processor (DSP) TMS320F2812. [Copyright &y& Elsevier]

Abstract: Recently multilevel inverters are gaining popularity due to reduced voltage stress across power switches and low total harmonic distortion (THD) output voltage waveform. However, device count increases with increased voltage levels. This paper presents a novel multilevel topology which is capable of obtaining all additive and subtractive combinations of input DC levels in the output waveform. Though all such levels can be obtained using the proposed topology, the actual number of levels depends on the DC source arrangement. A comparison is made between proposed topology and the classical multilevel topologies on the basis of device count and number of levels in the output voltage waveform. A detailed study of the proposed topology is presented through the example of a nine-level inverter. Appropriate modulation scheme is also presented. The proposed concept is analyzed through simulation studies and verified experimentally. [Copyright &y& Elsevier]

Abstract: The issue of renewable energy is becoming significant due to increasing power demand, instability of the rising oil prices and environmental problems. Among the various renewable energy sources, fuel cell is gaining more popularity due to their higher efficiency, cleanliness and cost-effective supply of power demanded by the consumers. This paper presents a comprehensive review of different fuel cell technologies with their working principle, advantages, disadvantages and suitability of applications for residential/grid-connected system, transportation, industries and commercial applications. Development of mathematical model of fuel cell required for simulation study is discussed. This paper also focuses on the necessity of a suitable power-conditioning unit required to interface the fuel cell system with standalone/grid applications. [Copyright &y& Elsevier]

Abstract: A Thyristor controlled series capacitor (TCSC) is a device which is used to increase the transmission line capacity. The TCSC device furnishes inductive as well as capacitive reactance compensation to alter the power flow of the transmission line. A difficulty is observed on tuning the TCSC device; large change in TCSC reactance ΔX at critical region (nearby resonance region) makes inconvenience for compensating any small change in dynamic demand at load end. This paper presents microtuning of line reactance by implementing split TCSC in place of single TCSC. The Newton Raphson method power flow analysis (NRPFA) is used to examine the fine microtuning of line reactance to compensate the small change in power demand. The mathematical modeling of NRPFA with single TCSC and split TCSC are studied. Comparison of power flow and power loss variation between single TCSC and split TCSC are also examined. Any violation of transmission line loading limits and voltage margin are verified and discussed while inserting TCSC in transmission line. The IEEE 14 bus system, IEEE 30 bus system and WSCC 9 bus system are considered as a case study. [Copyright &y& Elsevier]