Bharat Singh Rajpurohit

Bio: Bharat Singh Rajpurohit is an academic researcher from Indian Institute of Technology Mandi. The author has contributed to research in topics: Stator & Fault (power engineering). The author has an hindex of 13, co-authored 118 publications receiving 589 citations. Previous affiliations of Bharat Singh Rajpurohit include Indian Institute of Technology Kanpur & Indian Institutes of Technology.

Planning and optimization of autonomous DC microgrids for rural and urban applications in India

Abstract: This paper presents planning and optimization of standalone DC microgrids for rural and urban applications in India. Load profiles in the form of a rural village, an urban residential building and a business organisation are considered for the study. Using these load profiles, different microgrid configurations with generation from PV, wind turbine and biodiesel generators are constructed. Optimization studies are then carried out using Homer Energy software to determine the optimal system configuration which has the lowest cost of energy. Historical data of hourly solar irradiation and wind speed were also used in the study to obtain a realistic result. A special case study for the rural scenario with a partial connectivity to the grid is also conducted which is reminiscent to the poor reliability of supply in India. The study also gives a detail comparison between the various cost components, electrical productions, energy management and emissions for each of these systems. The results of optimization show reasonable cost of electricity for reliable supply of power for the various load configurations as compared to the actual grid prices.

A review on economics of power quality: Impact, assessment and mitigation

Abstract: The quality of electrical power supply directly influence the function and operation of the electrical devices feed by the electrical power system distribution network. Poor power quality(PQ) can cause peculiar operation of electrical devices which causes heavy economic loss to the customer and network operator. Poor PQ includes many phenomenon in which some are; voltage sag and interruptions, harmonics, surges, flickers, etc., and for each phenomenon the behaviour of electrical devices varies, which makes the quantification of losses due to poor PQ a complex subject. Among various PQ problems, voltage sag is more focussed by researchers from the mid of 90 s, because voltage sag directly affect the operation of electrical devices by causing interruptions (either small or large) in the process which further causes heavy economic losses. But the input (information) needed to quantify economic loss due to poor PQ varies from one method to other, and this makes a need to study the proposed methods and come to a meaningful conclusion. Quantification of cost of poor PQ (except voltage sag) is a research topic which has to be addressed to know the need of expenditure for smooth power supply. This research work includes some case studies to show the effect of PQ problems in various regions of the world. The paper includes a discussion on various indices and methodologies proposed by researchers in past to quantify PQ phenomenon, and some curves which shows the sensitivity of various equipments towards PQ problems. In this work one method is proposed for voltage sag cost calculation. At the end, proposed solutions of poor PQ problems and their implementation costs are also discussed and concluding remarks for the study is presented.

Review of fault modeling methods for permanent magnet synchronous motors and their comparison

Abstract: Modeling of Permanent Magnet Synchronous Motors (PMSM) is required for the mathematical representation of the machine in order to analyze the behaviour of the machine under different operating conditions. This paper gives a detailed study of various fault modeling methods of PMSMs and their comparison in terms of accuracy and computational time. Based on a thorough review, the fault modeling methods are classified into Electrical Equivalent Circuit (EEC) based methods, Magnetic Equivalent Circuit (MEC) based methods and Numerical Methods (NMs). This paper describes an in-depth study and analysis for each of the modeling methods and further summarizes them into a comparative study. It also draws an inference about methods which are preferable for different types of faults.

Comparative analysis of permanent magnet motors and switched reluctance motors capabilities for electric and hybrid electric vehicles

Abstract: This paper discusses about the relative analysis of permanent magnet motors and switched reluctance motors (SRM) capability of electric vehicles (EVs) and hybrid electric vehicles (HEVs) system. Nowadays the pollution of the environment is increasing due to conventional vehicles. Hence, to reduce the pollution electric motors are very beneficial. Presently use of high power density magnetic motors like, brushless DC (BLDC) motors and permanent magnet synchronous motors (PMSM) have been the primary choice in the EVs and HEVs. But these motors have problems with demagnetization, high cost and fault tolerance. Therefore, in future permanent magnet motors will be replaced with SRM for EVs and HEVs. Because of SRM have no permanent magnets on the rotor, higher torque to power ratio, low losses and low acoustic noise compare to BLDC motors and PMSM. This paper is based on the properties of the special electric motors for example performance analysis, power density control, torque ripple control, vibration control, noise and efficiency. In this paper, special aspects of the BLDC motors, PMSM and SRM based drive systems for the EVs and HEVs are offered and reviewed. Also explained why permanent magnet motors are replaced with SRM for applications in EVs and HEVs.

Demand-Side Management System for Autonomous DC Microgrid for Building

Abstract: This paper proposes a new demand-side management (DSM) scheme for the autonomous DC microgrid for the future building. The DC distribution system is considered as a prospective system due to the increase of DC loads and DC power sources such as photovoltaic (PV), and battery bank (BB). The BB responds to the changes in a power imbalance between PV generation and demand within an autonomous DC microgrid. The power loss during charging/discharging of the battery is the great challenge for the autonomous DC microgrid supplied by PV. It decreases the system efficiency. The control objective of the proposed DSM scheme is to use the PV energy more efficiently. The proposed control algorithm shifts the deferrable load from non-sunny hours to sunny hours and decreases the building demand during non-sunny hours. In this way it decreases the charging/discharging cycles of the batteries. This is reducing the power losses in the battery and improves system efficiency. The proposed scheme reduces the size of the PV plant, storage and capital cost of the system. The results showing a clear shifting of the load so that to get significant reduction in the system cost which is given numerically as percentatge saving.

A review and research on fuel cell electric vehicles: Topologies, power electronic converters, energy management methods, technical challenges, marketing and future aspects

Abstract: The implementations of fuel cells (FCs) in the vehicle industry have gained great attention for the last few decades owing to simple utilization, silent operation, high efficiency and modular structure. Technological advancements show that the use of FCs in electric vehicles (EVs) will increase rapidly and cause a revolution, and will be an alternative to traditional vehicles in the future. Commercial vehicles, projects and research show that work is underway to ensure that FCEVs have sufficient performance advances for their daily transportation needs. However, the lack of a detailed study that will shed light on researchers working in this field is obvious. It aims to provide a comprehensive scientific publication on the current status and future expectations to engineers and researchers interested in this field. In the current study, numerous studies have been examined in detail and added as supplementary to the bibliography. In this context, FCEVs are classified under headings of configurations, systems components, control/management, technical challenges, marketing and future aspects. First of all, FC types and electric motors are discussed in terms of their application areas, characteristic properties and operating conditions. Power converters, which are voltage regulation and motor drive topologies used in FCEVs, are detailed according to the structural frequency of use, structure, and complexity. In the next sections, control issues for converters and technical challenges are branched for FCEVs. In final section, the current status and future aspects are reported using a large number of marketing and target data.

Impact of distributed generation on protection and voltage regulation of distribution systems: A review

Abstract: During recent decades with the power system restructuring process, centralized energy sources are being replaced with decentralized ones. This phenomenon has resulted in a novel concept in electric power systems, particularly in distribution systems, known as Distributed Generation (DG). On one hand, utilizing DG is important for secure power generation and reducing power losses. On the other hand, widespread use of such technologies introduces new challenges to power systems such as their optimal location, protection devices' settings, voltage regulation, and Power Quality (PQ) issues. Another key point which needs to be considered relates to specific DG technologies based on Renewable Energy Sources (RESs), such as wind and solar, due to their uncertain power generation. In this regard, this paper provides a comprehensive review of different types of DG and investigates the newly emerging challenges arising in the presence of DG in electrical grids.

A review on overall control of DC microgrids

Abstract: Due to inherent advantages of DC system over AC system such as compatibility with renewable energy sources, storage devices and modern loads, Direct Current Microgrid (DCMG) has been one of the key research areas from last few years. The power and energy management in the DCMG system has been a challenge for the researchers. MG structure and control strategies are the integrated part of the power and energy management system. This paper covers all the aspects of the control of DCMG, whether it is DC bus voltage, power or energy related. Different MG Structures with their comparative analysis has been given in this paper. Various control schemes: Basic control schemes like centralized, decentralized and distributed control and multilevel control scheme such as hierarchal control has been discussed. The Power management in grid-connected, Islanded mode and transition mode has been presented. Different energy management strategies have been presented as energy management plays very important role in optimizing the size and rating of energy storage system and their maximum utilization. The energy management of a battery and super capacitor based HESS in all configurations has also been discussed and finally, future trends in further research are presented.

DC Microgrid Planning, Operation, and Control: A Comprehensive Review

Abstract: In recent years, due to the wide utilization of direct current (DC) power sources, such as solar photovoltaic (PV), fuel cells, different DC loads, high-level integration of different energy storage systems such as batteries, supercapacitors, DC microgrids have been gaining more importance. Furthermore, unlike conventional AC systems, DC microgrids do not have issues such as synchronization, harmonics, reactive power control, and frequency control. However, the incorporation of different distributed generators, such as PV, wind, fuel cell, loads, and energy storage devices in the common DC bus complicates the control of DC bus voltage as well as the power-sharing. In order to ensure the secure and safe operation of DC microgrids, different control techniques, such as centralized, decentralized, distributed, multilevel, and hierarchical control, are presented. The optimal planning of DC microgrids has an impact on operation and control algorithms; thus, coordination among them is required. A detailed review of the planning, operation, and control of DC microgrids is missing in the existing literature. Thus, this article documents developments in the planning, operation, and control of DC microgrids covered in research in the past 15 years. DC microgrid planning, operation, and control challenges and opportunities are discussed. Different planning, control, and operation methods are well documented with their advantages and disadvantages to provide an excellent foundation for industry personnel and researchers. Power-sharing and energy management operation, control, and planning issues are summarized for both grid-connected and islanded DC microgrids. Also, key research areas in DC microgrid planning, operation, and control are identified to adopt cutting-edge technologies. This review explicitly helps readers understand existing developments on DC microgrid planning, operation, and control as well as identify the need for additional research in order to further contribute to the topic.