The chapter deals with an overview of the rural electrification with DC microgrid and the introduction to electric vehicles (EVs). The best option for rural electrification is the reliable and standalone system. DC microgrid requires less maintenance, which is advantageous in the rural areas. The most significant development in DC microgrid increases the utilization of batteries and EV as energy storage (ES) devices in the microgrid. The utilization of such sources improves the system reliability and efficiency as these balance the system power. This requires a proper load or source scheduling. DC microgrid provides the horizontal infrastructures to integrate distributed generation and loads.

This chapter presents a general description of microgrids (MGs), illustrating basic characteristics and structures of MGs with the objective of providing general background information on MGs that will help one to better understand the best promising structure and architecture in designing such systems. At present, AC MGs are still the main arrangement of MGs, even if they involve some drawbacks such as the need for synchronization of DG units, the circulation of reactive power and electromagnetic compatibility problems due to the intensive use of AC/direct current (DC) converters. Recently, DC MGs are emerging as a possible solution to avoid the aforementioned problems for a few isolated DC devices that must be connected into ex-novo networks. Although DC-powered components for residential and industrial applications are going to be more and more developed, the vast majority of existing devices currently in use in every area are fed in AC.

This chapter presents different methods and tools for microgrid optimal investment and planning problem, focusing on specific methodological aspects addressing the challenges of rural microgrids design. In particular, three aspects of rural microgrids planning are analyzed: (1) the multi-energy nature of rural microgrids, where electricity coexists with other energy vectors (such as heat distribution); (2) the occupation of large portions of the rural territory, which requires planning methods to consider the microgrid internal network constraints; (3) the remote (and sometimes off-the-grid) locations of rural microgrids, which require security criteria and multi-objective approaches to be considered in planning problem. These three methodological aspects are discussed using the example of a real microgrid in Alaska.

The coordinated controls of voltage reduction (CCVR) technique as one of the functions of demand side management has been rolled out in many power utilities in the United Kingdom to provide fast energy demand reduction (EDR) for a microgrid when the distributed generation is low. With the advance of new lowcarbon technologies (LCTs), different load types, such as heat pumps and electric vehicles (EVs), are emerging. This paper assesses the impact of different EV charging models on the EDR performance. The CCVR technique is considered for both an urban and a rural microgrid, respectively. The Monte Carlo (MC) method is applied to analyze the impact of three different EV charging models (i.e., uncoordinated charging (UC), vehicle-to-grid (V2G) charging and mixed charging (MIX)) on the grid EDR performance. In comparison with different EV charging strategies, the impact of V2G strategy on the grid EDR capability is the least, while the MIX strategy can help the grid to increase EV penetration capability more effectively.

A microgrid (MG) is a localized group of electricity loads and distributed energy resources (DERs). The DERs consist of the renewable energy resources, in which the wind farm and solar technologies have gained increasing interest and growth in the recent years. The renewable energy sources (RESs) such as wind and solar ones have the variable output power because of their stochastic nature. So, the energy storage systems (ESSs) have been investigated as achievable solution to solve the output power fluctuation ofRESs. This chapter studies the different types of energy storage device technologies considering characteristics and operation constraints for MG use. The technologies of ESSs have the important role on the application of ESSs for MG use. The battery energy storage has a poor life cycle and influences the MG future development. The main characteristics of ESS technologies are the important things in the future development of MG. The ESSs are used as peak shaving, renewable energy systems integration, spinning reserve, load following, frequency regulation and black start in the MG application.

In this chapter, authors present the control technique for integration of smart dc microgrid (DCMG) to the utility grid. A ring-type architecture of “smart DCMG” for integrating various renewable and nonrenewable distributed generators (DGs) and different dc and ac loads, using power electronic converters, is presented. A bidirectional three-phase voltage source inverter (VSI) has been used to integrate the DCMG to the utility grid as well as the three-phase loads. In this chapter, a control technique of the bidirectional three-phase VSI into two rotating d-q synchronous reference frames (SRFs), using the feedback and feed-forward control loops, has been proposed. In the proposed control technique, the dual controllers have been suggested for controlling the positive-sequence components as well as the negative-sequence components of both three-phase ac voltage and current, independently, in its own SRF. The performance analysis of the smart DCMG along with the developed control technique is also carried under different operating scenarios, in this chapter.

This chapter focuses on the energy management system (EMS) for a microgrid (MG). The hierarchy of the various controllers utilized in the EMS is presented. Various programming methods can be used for optimizing the behavior of the EMS such that the MG can operate in a safe and reliable manner to match the demanded load with the available energy sources. The requirements for a communication system within the MG are briefly discussed. A test case with a particle swarm optimization (PSO) technique is provided.

This chapter proposes a new efficient concept of optimal reconfiguration that uses the AGWO algorithm to study the optimal reconfiguration of radial distribution system for power losses reduction. The AGWO is used to determine the optimal switches that can be opened to reconfigure the distribution system and to obtain the minimum system power loss. The simulation results of the IEEE 33-bus show that after reconfiguration, system power loss reduction is 38.0074%. From simulation results, it is observed that the AGWO achieves superior results when compared with other optimization techniques. The convergence characteristic of the AGWO proved that it is able to solve difficult optimization problems in different fields.

Economic and technical issues have contributed to difficulties experienced in accessing or supply of electricity in areas far away from the main electrical grids, such as islands. However, the implementation of the microgrids, integrated with the renewable energy sources, has contributed to ensuring that these areas are supplied with electricity. Besides, systems incorporating renewable energy and energy storage systems (ESSs) have and continue to play a significant role as an energy supply solution for these areas, through improved reliability and efficiency of the system. In full appreciation of the impacts of ESS, a novel multi-objective intelligent scheduling formulation is proposed that considers batteries life loss cost, operation cost, and uncertainty costs associated with the variability of renewable sources. Mitigation of issues due to intermittency of renewable energy sources through ESSs is demonstrated, using a non-dominated genetic algorithm (NSGA II). The test system used corresponds to a microgrid in an island with similar features of a real microgrid in Dongfushan Island in China.

In this chapter, we will focus on the primary and secondary controls for proper power sharing and set-point restoring operations of MGs. Traditionally, the power sharing is achieved by the decentralized droop scheme of each DIC. Although proper real power sharing can be achieved in most existing methods, incorrect reactive power sharing has been observed. In recent years, advocates of distributed multiagent systems (MAS) have been broadly adopted as promising solutions for MG control and operations. Under this framework, the primary control and the secondary control can be efficiently integrated into a single distributed task.

High gain converters are very popular nowadays due to large demand in the area of microgrid-based renewable energy resources. The renewable energy resources have low-voltage generation sources that require high voltage gain converters to step up the input DC voltage. Also, multi-output converters are demanded in the present scenario due to a requirement of different AC and DC load demands. The conventional converters used for this purpose have a few limitations such as duty cycle is limited and they have to operate on extreme duty cycle to achieve high gain. To encounter these problems, hybrid multi-output converters are designed and proposed for high gain in less duty cycle. In this chapter, an extendable multiple-output hybrid converter is presented for AC/DC microgrid applications. The proposed converter is derived from single-switch-derived quadratic boost converter topology. In the proposed hybrid converter, both the filter inductors of the converter are magnetically coupled and the main switch of the converter is replaced by an H-bridge inverter circuit. This inverter bridge can be arranged by series or parallel and depending upon the need of output voltage and current, an n-number of bridges can be connected in series or parallel. Thus, the proposed hybrid converter is capable of giving single DC and n-number of AC outputs simultaneously. This type of converter topologies is mostly suited for rural-based microgrid application where requirements are of less maintenance, high power density and less cost. Detailed steady-state analysis and PWM control algorithm for both series and parallel connected topologies have been carried out to demonstrate its advantages. In this chapter, the proposed topology is validated for two simultaneous AC and single DC outputs on a 500 W prototype through simulation and experimental results.

In this chapter, the multi-input converters for distributed generation (DG) resources in Microgrids are introduced and categorized. In the past, some DC/DC converters used to be connected parallel to each other and thus multiple converters were created. But today, many structures have been proposed for this purpose. The main reason behind employing these converters is to get the following features based on their application and topology: fewer semiconductors, less volume, fewer switches' stress, simple control, low power loss, high efficiency, high gain, low manufacturing cost, etc. In this chapter, multi-input converters are categorized into three groups based on their structure: magnetic, electrical, and electromagnetic types. The first group includes topologies that have a multi-winding transformer. The second group consists of topologies that have DC-link and sources connected to the DC-link, and the latter contains topologies that have DC-link and transformer. In this chapter, the topologies of various multi-input DC/DC converters will be reviewed and compared from different aspects such as the battery life, the soft-switching, the source utilization, the isolation between the input and the output. This chapter providing an information source in the selection guide on multi-input DC/DC converters of DER in Microgrids for researchers, designers and application engineers.

In a DC microgrid system connected to photovoltaic distributed generation system, DC-DC converters play an important role to perform various functions. In this chapter, a DC microgrid system is presented in which DC-DC converter is utilized to regulate the DC bus voltage under different operating conditions. This chapter focuses on design, modeling, and control of a DC-DC converter. Considering DC-DC buck converter as an example, a systematic procedure is explained to obtain its mathematical model using the state-space averaging (SSA) approach. The steady-state and dynamic models of the buck converter connected to PV systems are derived. Finally, a control design algorithm is discussed to regulate the DC bus voltage in the presence of variations in PV voltage, DC busload, and reference DC bus voltage. The simulation and experimental results are demonstrated in order to validate the controller performance under various aforementioned operating conditions.

Microgrids (MGs) are becoming more attractive due to their ability to reduce energy costs for customers, allow the full exploitation of renewable energy sources and increase security, reliability and resiliency of the power distribution system. Moreover, the integration of MGs into power systems will alleviate the consequences of sudden grid outages on the end users and provide higher power security to critical loads. In addition, thanks to their ability to produce energy close to the consumption points, MGs offer a possible solution for reliable energy supply into the areas where the extension of power grids is considered technically and economically unfeasible. Nonetheless, their practical implementation into actual distribution networks is still hindered by several technical and economic issues. This chapter aims to show, by using several Case Studies of MGs, the value of each MG system in providing energy efficiency, ancillary services, demand response and electricity bill reduction.

The power of a conventional plant and that of a photovoltaic (PV) system are the same. In typical applications, a limited grid network, heating, ventilation and air-conditioning systems with remote water pumping for remote islands include the supply of electricity to villages. Turkey's energy dependence on imports, mainly on oil and natural gas (NG), has been increasing because of the growth in energy demand. Turkey has achieved the highest growth rate of energy demand in OECD countries over the last 12 years. Currently, Turkey is able to meet only about 26% of the total energy demand from its own domestic resources. On the one hand, the institutions responsible for the transmission and distribution of electricity and NG are privatized in Turkey, but on the other hand, works for the optimization of transmission and distribution networks are in progress. Although applications are made for the exploitation of transmission and distribution networks at an optimal level, the competent public authorities enforce new regulations in this context, with the aim of ensuring bilateral information flows between consumers and suppliers. Turkey has two interconnection points with the East European Transmission Grid. The test period for a synchronous parallel operation between the Turkish and European power systems had started on 1 June 2011 and ended in September 2012. At this moment, the trade is limited to 400 MW from Bulgaria and Greece to Turkey and 300 MW from Turkey to Europe via these countries. In order to provide a stable, low-cost, reliable, efficient, robust, sustainable and environment-friendly electrical energy system to consumers, a fully operational smart grid (SG) system needs to be established in Turkey. If classical grids in Turkey were transformed into SGs, not only would the above-mentioned benefits be achieved, but also Turkey would be able to attract a huge amount of investment to boost its economy. The Turkish grid system would then become a powerful player in the energy market in Europe.

The Republic of Colombia is a country situated in the northwest of South America, with territories in Central America. In 2005, the interconnected electricity system served 87% of the population, a percentage that is below the 95% average for Latin America and the Caribbean. The Colombian government is making massive efforts to increase the electrification, especially at very remote and rural places. However, there are still several rural communities isolated from the main grid in Colombia. Also, although some communities have already been connected to the distribution system, the security and reliability are still an issue. One key element in the effort of electrification is the use of very small microgrids projects called “nanogrids.” A nanogrid is a small power system that uses a combination of renewable and conventional energy sources to supply power to small local loads. The total load in a nanogrid is typically less than 20 kW, as an industrial site, small rural village. or a household. The generators are primarily based on clean energy such as solar arrays, wind turbines, and fuel cells. In Colombia, the Caribbean coastline, Andes Mountains, and strong agriculture provide the country with abundant distributed renewable energy resources that might largely surpass the fast-growing electricity demand. In this framework, the nanogrids emerge as a solution to supply energy for some communities, located far away from the network, improving the inhabitant's quality of life. Moreover, the nanogrids might improve the security and reliability levels of the distribution system. This chapter discusses good practices and proposed some solutions to overcome challenges detected in nanogrid projects developed in Colombia. In essence, this chapter is a case study of nanogrid systems; it focuses on a full detailed explanation of 23 nanogrid projects developed in Colombia considering location, installed power, purpose, etc. Then the nanogrid projects are evaluated, and it gives the opportunity to identify some characteristics that hinder or benefit the operation of these systems. Some of them are the growth of the demand, the appropriate and inadequate use of energy and drinking water, the changes of habits in the users in the presence of energy or the increase in the reliability of the energy supply and how it affects the maintenance or lack this, the operation of the systems.

One of the most exceptional perspectives of the industrial growth taking place worldwide is the continued and abnormal increase in the energy demand. Concerns regarding the economic and environmental impacts of conventional energy sources have driven researchers and inventors to create more efficient, and less costly approaches for delivering electric energy. Utilizing renewable energy-based Distributed Generations (DGs) are likely to be employed and integrated into the Distribution Network (DN) increasingly as a prominent alternative to conventional energy sources used so far. The increased penetration of bulky DG units to the electrical network created fundamental shifts and changes in the philosophy of the operation and protection of DNs. The design of a particularly suitable protection scheme is one of the most significant technical problems associated with the integration of DG. In this study, The effects associated with the integration of DGs into The Libyan medium voltage-DN have been highlighted and discussed in details. In particular, the insufficiency of the utilized protection practices thoroughly investigated and explained. Generally applicable approaches are recommended, which can enhance the applied protection schemes in the interconnected-DN.

The Chapters in this book concentrate on case study-based research and/or solutions for rural electrification. The book covers energy storage along with its integration with the DC microgrid (MG) and related challenges. The low-voltage DC distribution system for various applications like charging electric vehicles is also discussed. This conclusion gives a short summary of each Chapter.