Dynamic Distribution System Reconfiguration Considering Distributed Renewable Energy Sources and Energy Storage Systems

High level challenges that motivate the evolution towards smart grids include (i) the anticipated electrification of transportation, including electrical vehicles (EVs), and (ii) the increasing penetration of distributed renewable energy sources (DRES). This chapter will discuss how the extra grid load stemming from the EVs can be handled, including the context of reduced control over power generation in light of DRES adoption (especially solar and wind power). After a basic introduction to common EV charging technology, we give two illustrative examples of controlling EV charging: avoiding peaks, and balancing against renewable generation. We then qualitatively present possible demand response (DR) strategies to realize such control. Finally, we highlight the need for, and underlying principles of, (smart grid) simulation tools, e.g., to study the effectiveness of such DR mechanisms.

A high peak demand causes the escalating cost of electricity costs for both the utility and end-users. This paper investigates the challenges raised by the high peak demand and the state-of-the-art technologies adopted to reduce the peak demand. The peak shaving technologies can be categorized into four groups. The first category is peaking power plants which include the open-cycle gas turbine (OCGT) power plants and hydroelectric power plants. The second category is the energy storage system (ESS) comprising of the pump hydro storage (PHS), compressed air energy storage (CAES), battery energy storage (BES), flywheel energy storage, thermal energy storage (TES) and hydrogen fuel cell. The third category is the hybrid renewable energy – storage system (HREES) that combines the renewable energy (RE) and energy storage system. The fourth category is the demand-side management (DSM. The advantages and shortfalls of these technologies are highlighted in this paper.

Guest Editorial: Situational awareness of integrated energy systems

Energy-efficient system and charge balancing topology for electric vehicle application

We calculate the energy demand of automated vehicles for different driving cycles. We alter standard driving cycles to depict the driving behavior of automated vehicles. We further assume additional energy demand for automation systems and investigate trade-offs between reductions in mechanical energy demand and increases in auxiliary energy demand. In the case of trucks, we find that smoother driving and the additional energy demand offset one another for highway driving. However, a notable reduction in energy demand can be achieved by lowering the maximum driving speed. For cars, we find that the additional energy demand slightly outweighs the effects of smoother driving on highways. When considering city driving, the additional energy demand increases the energy demand of a mid-size car in the standard driving cycle by one third. Reducing driving speeds and stops is not able to offset this increase in energy demand.

To meet the fast-growing energy demand and manage the distributed resource, an intelligent energy management system plays a vital role in the electric power system. The next-generation electric power system, known as the smart grid, will incorporate a large number of renewable energy resources that fundamentally change the energy management paradigm. To manage efficiently the energy supply and demand in the power grid, further improvement in the reliability and efficiency of electrical grids can be achieved by utilizing dc distribution in microgrid systems. DC microgrid is an attractive technology in the modern electrical grid system because of its natural interface with renewable energy sources, electric loads (e.g. data center load, electrical vehicle charging load, residential dc load), solid state transformer and energy storage systems. In this paper we discussed the functional expectation of the dc microgrid, system architecture, communication structure and distributed grid intelligent system. This paper highlights the recent technology update in dc microgrid system. This paper also discusses benefits and challenges of using dc grid.

This paper investigates the problem of designing cellular manufacturing systems with multi-period production planning, dynamic system reconfiguration, operation sequence, duplicate machines, machine capacity and machine procurement. An important aspect of this problem is the introduction of routing flexibility in the system by the formation of alternate contingency process routings in addition to alternate main process routings for all part types. Contingency routings serve as backups so as to effectively address the reality of part process routing disruptions (in the main routings) owing to machine breakdowns and allow the cellular manufacturing system to operate in a continuous manner even in the event of such breakdowns. The paper also provides in-depth discussions on the trade-off between the increased flexibility obtained versus the additional cost to be incurred through the formation of contingency routings for all parts. Some sensitivity analysis is also performed on some of the model parameters. The problem is modelled and solved through a comprehensive mixed integer programming formulation. Computational results presented by solving some numerical examples show that the routing and process flexibilities can be incorporated within the cellular manufacturing system design without significant increase in the system cost.

It is known that glazed openings are very important elements in the energetic behavior of buildings, especially in Mediterranean climates where there are many hours of solar radiation. The objective of this study was to determine the influence of solar protection on the energy demand of public housing structures in these climates. To this end, the reduction in energy demand achieved by fixed solar protectors in combination with mobile protectors (blinds) was quantified, including an evaluation of the influence of their geometry, dimensions, degree of openness, and the orientation of the opening. To analyze and quantify energetic demand, a block of public housing units in a neighborhood of Seville (latitude 37°23' N) was used as a model. This block is typical of public housing in the Mediterranean region. Simulated energetic models were created using DesignBuilder, achieving reductions in the annual energy demand from 10% to 27% according to the orientation chosen. The results and conclusions of the study are applicable to new construction, energetic rehabilitation projects, and/or the improvement of existing buildings.

A microgrid (MG) is a discrete energy system consisting of an interconnection of distributed energy sources and loads capable of operating in parallel with or independently from the main power grid. The microgrid concept integrated with renewable energy generation and energy storage systems has gained significant interest recently, triggered by increasing demand for clean, efficient, secure, reliable and sustainable heat and electricity. However, the concept of efficient integration of energy storage systems faces many challenges (e.g., charging, discharging, safety, size, cost, reliability and overall management). Additionally, proper implementation and justification of these technologies in MGs cannot be done without energy management systems, which control various aspects of power management and operation of energy storage systems in microgrids. This review discusses different energy storage technologies that can have high penetration and integration in microgrids. Moreover, their working operations and characteristics are discussed. An overview of the controls of energy management systems for microgrids with distributed energy storage systems is also included in the scope of this review.

The World's energy consumption has increased drastically over the past several decades, particularly driven by increasing population and economic activities as well as rising living standards with technological advancements. Since the industrial revolution, fossil fuels have been the major source of energy productions, which is today shown as the primary cause of the ongoing climate change and associated environmental challenges in threatening the existence of many living species and human life and comfort. According to the statistics provided by International Energy Agency (IEA),1 the global energy supply was 14 282 Mtoe in 2018 that is 115% higher than that of the value for 1973. Fossil fuels, such as natural gas, coal and oil are still playing a critical role and covering more than 80% of global energy demands. The concerns associated with global warming and depletion of energy sources have been directing the attention to renewable and environmentally-benign energy solutions. However, efficient, affordable, and nature-friendly energy storage systems are the key to using renewable energy sources effectively. In this study, a comprehensive literature search is conducted to study and bibliografically evalute Canada's energy storage research and development activities over the last five decades. The present study intends to present the cumulative picture on energy storage reseach and development efforts and assess how universities, research institutes and funding agencies have contributed to this particular field. The literature search compiles a total of fifty-year data on energy storage-related research and development activities conducted in Canada. The number of conducted studies associated with energy storage regarding research articles, books, research projects, dissertations, and patents is presented in the period from 1971 to 2021. Furthermore, the Canadian institutes are ranked based on their scholarly ouputs and publications to indicate the most productive ones in the field of energy storage based on the data presented in the literature sources. Energy storage is described as the capture of harvested energy for later use to maintain the balance fluctuations between energy demand and supply. As the world moves towards a low-carbon economy, energy storage systems are exepcted to even play a more critical role in extracting more energy from renewable resources.10 The intermittent characteristic of renewable resources, specifically solar and wind, is one of the major challenges ahead of a reliable and steady renewable energy supply. This can be avoided by storing excess energy to re-use when the renewable resources are not sufficient or unavailable. Energy storage systems can be categorized in different ways in regards to the form of converted and stored energy. Figure 1 presents an overview of energy storage system categories which are considered in this study. It is important to note that chemical energy storage allows to storage and transportation of large amounts of energy for long distances with minimal self-discharge rates, which is crucial for the distribution and effective use of renewable energy resources. Figure 2 presents the energy density of various chemical fuels and batteries. Despite possessing high energy density, environmental concerns associated with the production and consumption of fossil-based chemical fuels, e.g. diesel, gasoline or natural gas, should be adrressed. In regards to nature-friendly chemical energy storage, particularly power-to-gas chemical storage, hydrogen is attracting favorable attention nowadays. In this regard, hydrogen appears to be the lightest and most abundant chemical element in the universe, but is not available freely (by itself). However, it occurs naturally within a compound such as water (H2O); therefore, it is an intermediate energy form. Excess electricity from renewables can be utilized in hydrogen production processes, i.e. electrolysis of water, to store energy in chemical form. Power-to-hydrogen chemical energy storage is a unique and clean method, and it can be compatible with electrochemical storage since hydrogen possesses much greater energy content. One of the major challenges with hydrogen is the low calorific value per unit of volume (MJ/m3) due to its low density. This can be avoided by deploying alternative hydrogen carriers, such as ammonia. Liquefaction at atmospheric conditions, high hydrogen atom content and high energy density characteristics make ammonia a favorable medium for storage and transportation of energy. It is further to note that batteries and capacitors are devices allowing electrochemical storage of electricity. The potential energy is stored in chemical form in batteries, while capacitors are expected to store their potential energy in the form of an electric field.14 Batteries are thus most commonly used and matured options that propose high energy densities and voltages. Lithium-ion (Li-ion), sodium-sulphur (NaS), nickel-cadmium (NiCd), lead acid (Pb-acid), lead-carbon batteries, zebra batteries (Na-NiCl2) and flow batteries are the existing battery types used in various applications. Due to their high specific energy (per unit weight) and high specific energy (per unit volume), lithium batteries attract considerable attention in electrical energy storage. Capacitors can be classified as electrostatic capacitors, electrolytic capacitors, and electrochemical capacitors, among which electrochemical, so-called supercapacitors, promote the highest capacitance per unit of volume owing to a porous structure 15. As a mechanical energy storage method, pumped hydro accounts for more than 95% of the global installed energy storage capacity.15 The main advantage of mechanical energy storage is to readily deliver energy. The method is easy to adapt for conversion and storage of energy from various sourcessuch as water current, wave, or tidal. Pumped hydro, compressed air, and flywheel are the commonly practiced mechanical energy storage methods. Pumped hydro and compressed air are bound to specific geographical characteristics, which is the main restriction for the implementation of these energy storage methods. A flywheel stores the energy obtained from a rotor mass spinning at very high speeds as kinetic energy. The stored kinetic energy can be later used to produce electricity by altering the angular velocity of the flywheel through a decelerating torque and using an electric motor in reverse 16. Despite of being non-suitable for long-term energy storage, flywheels offer favorable advantages, that is, long-life spin, high energy densities and low maintenance costs, and fast charging.17 Thermal energy storage (TES) systems are effective systems to store heat in a reservoir for a period of time (defined or undefined) for later use, that is, space heating and cooling, electricity production, hot water. If the reservoir temperature is kept under the atmospheric temperature, the storage process is called cold thermal energy storage.18 Operating temperature range, capacity requirements, charging and discharging requirements are some of important parameters when choosing an appropriate TES system for a desired application. Since the major proportion of produced and consumed energy is heat around the world, TES systems carries a significant weight regarding the development of effective energy systems . Furthermore, energy losses from the systems commonly occur in the form of heat. Decreasing losses via further utilizing from waste energy is one of many way to mitigate environmental impacts, which can be accomplished by implementing TES systems in a cost effective manner. In the current study, an overview of Canada's energy storage related studies from 1971 to 2021 is presented. The scope of this study is to present the contributions of Canadian universities, research institutes and funders to energy storage research and development efforts over the last five decades. The keywords and methodology that are used for the literature search are depicted in Figure 3. The collected and compiled data for the corresponding fields are presented in figures, and results are discussed in the following sections. In this study, an online literature search is conducted on Canada's energy storage related studies over the last five decades. The current section presents collected and compiled data in charts. The findings of the conducted study are discussed in detail. The most productive institutes of Canada regarding conducting or sponsoring energy storage-related studies are presented. The documents associated with energy storage in all subject areas are presented in Figure 4. In this regard, the highest number of energy storage-related studies were conducted in the subject area of engineering in Canada from 1971 to 2021. The fields of energy and chemistry appear as the other two major subject areas in which high number of energy storage research was conducted. While compiling data, attention has been paid to any potential field conflicts concerning the multi attribution of interdisciplinary publications. Therefore, it should be noticed that chemistry may have an impact on the subject areas of biochemistry, genetics, and molecular biology. The same impact of engineering could be seen on the subject area of energy. The data collected and analysed for comparative evaluation reveals that the Canadian institutes have produced 37 386 energy storage-related academic research publications over the last 50-year period. In this regard, Figure 5A presents the breakdown of energy storage-related publications affiliated to Canada in the corresponding material types in accordance with the publication years. Figure 5A shows that studies in this field consistently increases every year. Consequently, the year 2020 appears as the most productive one in this regard as of April 2021. In the light of this trendline, predicting that the year 2021 will be more productive than 2020 would not be wrong. Figure 5B has been prepared as a heat map to show Canada's provinces where energy storage-related studies were conducted over the last 50 years. In this regard, Ontario appears as the most productive province of Canada in terms of scholarly publications. However, one has to keep in mind that Ontario has the highest number of contributing institutes/universities compared to the rest of the provinces in Canada. Figure 6 presents the breakdown of the number of energy storage-related books, book chapters, and editorials in accordance with publication years in Canada. The year 2018 was the most productive year of Canada by producing 200 documents in the corresponding classification. The other important point that should be pinned in the figure is the year 2005. Compared to the previous year, almost five times more energy storage-related books were published in 2005. Compared to 2019, the number of published books decreased almost by half in 2020. The impact of COVID-19 is recognized as one of numerous reasons behind this result. The number of energy storage-related dissertations completed in Canada over the last five decades is primarily searched through and collected from Library and Archives Canada. The search results are, in this regard, presented in Figure 7. It can be noted that the data presented in Figure 7 is based on the number of energy storage-related theses available in the library; and thus, the results are subject to change in accordance with instantaneous new data entry to the library. As of April 2021, there are 626 energy storage-related MSc and PhD theses/dissertations entered in the online system of Library and Archives Canada. The highest number of theses/dissertations was recorded in the year of 2013 with a value of 62. Based on data collected from the website of Canadian Intellectual Property Office, the number of energy storage-related patents of Canada is 11 719 for the last 50 years. The corresponding results are presented Figure 8. According to this, the year of 2018 appeared to be the Canada's most productive year in terms of patents registered under the title of energy storage. Canada is blessed with institutions that have been supporting energy storage-related research and developments by providing funds. Over the evaluated period of 50 years, the Natural Sciences and Engineering Research Council of Canada (NSERC) appears as the major funding agency for Canada's energy storage related research, development, partnership, strategic innovation and commercialization efforts and has supported more than 8500 projects in the field of energy storage. A total number of projects that have been funded by Canadian institutes have become 18021 from 1971 to 2021. It is most likely to observe a major increase in the number of projects by the impact of the recent hydrogen strategic plan of Canada. Being an excellent energy storage medium is one of many advantages of hydrogen. Therefore, there is a significant correlation in between hydrogen and energy storage research efforts. The subject matter report is already named as call-to-action for green hydrogen transition for the energy sector. In the report, the importance of dedicating more domestic resources to green hydrogen efforts to achieve the targets by 2050 is emphasized clearly (Figure 9). The development and implementation efforts of effective, affordable, and nature-friendly energy storage systems are recognized as a key requirement in achieving a green energy transition. In this regard, Canada intends to be the country leading and inspiring many others. Figure 10 shows the a number of Canadian institutes/universities that have produced more than 100 scholarly publications on energy storage under the subject area of energy. According to this, the total number of such scholarly publications has been 9125 over the past five decades. The results clearly show that there are two universities, such as University of Waterloo with 809 publications and Ontario Tech. University (formerly University of Ontario Institute of Technology) with 697 publications, leading in this particular area. University of Waterloo appears as the most productive Canadian university with a total number of 809 publications while Ontario Tech. University, which is one of the Canada's youngest universities, follows with a total number of 697 publications. The specific affiliations in the publications show that the researchers working in the productive environment of Clean Energy Research Laboratory (CERL) at Ontario Tech. have played a major role in this achievement. The data that support the findings of this study are available in Scopus, Library and Archives Canada and Canadian Intellectual Property Office with the reference number of [17], [18], and [19], respectively. These data were derived from the following resources available in the public domain: https://www.scopus.com/search/form.uri?display=basic&zone=header&origin, https://www.bac-lac.gc.ca/eng/services/theses/Pages/search.aspx, https://www.ic.gc.ca/opic-cipo/cpd/eng/search/basic.html?wt_src=cipo-patent-main.

Due to the aim of developing sustainable energy systems, promoting the large‐scale accommodation of distributed renewable energy sources (DRESs) and flexible loads in DC distribution networks (DCDNs) is significant. The uncertainty of DRESs and the insufficient use of flexible loads pose a considerable challenge to the economical and safe operation of DCDNs. To address the challenge, this paper puts forward a two‐stage optimal scheduling model for the DCDNs considering flexible load response. The proposed model realises joint economic optimisation and reactive power optimisation, which is solved by the hybrid NSGAII‐MOPSO algorithm and the CPLEX. The performance of the proposed model in the modified Institute of Electrical and Electronics Engineers 33‐node system with the DCDNs is validated under different scenarios. The hybrid NSGAII‐MOPSO performs better in obtaining the Pareto front than the NSGA‐II and MOPSO individually. Compared to the traditional scheduling model, the proposed model can realise the power coordination of the flexible loads and energy storage systems to reduce the negative impact of uncertainty of DRESs while decreasing operating costs and carbon emissions by 3.94% and 36.4%. In addition, the proposed model can alleviate the network losses and ensure the node voltage for the DCDNs. Hence, the efficiency of the proposed model has been confirmed.

Integrating non-dispatchable renewable energy sources (RES) such as wave farms into electric power systems presents inherent challenges. Specifically, the variability of the resource and its non-dispatchable) nature introduces power imbalances and power system stability problems in the system over both short and medium terms. This issue is particularly relevant for isolated power systems, such as those found on several European islands, where interconnection with the mainland is lacking. Therefore, although wave energy has significant potential for integration into island power systems due to resource availability, determining the maximum RES penetration that such systems can sustain while maintaining stability is not straightforward. Power system stability is closely tied to frequency. A well-established solution for improving the stability of isolated systems when integrating non-dispatchable RES is to install devices capable of responding to over- or under-frequency events, such as energy storage systems (ESS). The literature extensively discusses ESS control techniques for frequency regulation, with one of the most straightforward approaches being to operate the ESS according to a droop control strategy (similar to a statism). In this method, the power dispatched or stored by the ESS increases proportionally to the deviation from the frequency reference value. This paper presents a case study analyzing the frequency stability of an island power system equipped with an energy storage system (ESS) when integrating a wave farm. Frequency stability is evaluated based on two variables: wave energy penetration and the ESS droop control parameter. The case study is based on the island of El Hierro (Canary Islands, Spain), an isolated electrical system with a very high penetration of RES. The island’s electrical generation system consists of a wind farm, a pumped-storage hydroelectric power plant, and conventional generation from a diesel power plant. The analysis is conducted through simulations in MATLAB Simulink. A wave farm is modeled to evaluate the generated power and its associated oscillations, based on the wave energy resource at various locations along El Hierro’s coast. Additionally, an aggregated inertial dynamic model of the electrical power system is employed to assess the impact of the wave energy farm's generation on the system’s frequency and the aging that the frequency excursions introduce in the elements of the system. The Spanish Grid Code is considered to ensure compliance with frequency regulation mechanisms in isolated systems. Simulations are performed across different scenarios, varying both the nominal power of the wave farm and the ESS droop control parameter, in order to evaluate the ESS capacity. The results identify the optimal droop control parameter for each wave farm size to ensure frequency remains within acceptable thresholds. Furthermore, the minimum ESS capacity required for each wave farm size is determined from the simulations. These findings provide a basis for ESS and wave farm dimensioning, which could be translated into economic terms to maximize revenue (this aspect is beyond the scope of the present work).

This paper proposes a hierarchical look-ahead framework to conduct conservation voltage reduction (CVR) when distributed energy resources such as solar photovoltaic (PV) systems and energy storage systems (ESSs), and demand response programs are integrated into distribution systems. With the increasing deployment of PV systems in distribution systems, their frequently varying power output due to cloud movements could have a detrimental impact on the consumer’s voltage quality, consequently leading to degraded CVR performance. A two-level CVR framework for the coordination of an on-load tap changer (OLTC), capacitor banks (CBs), and the smart inverters of PV systems/ESSs is presented, in which these elements operate to reduce the voltage profile along the distribution feeder at different temporal scales. At the global level, the operations of the OLTC and the CBs are scheduled every hour to achieve the best CVR performance in an optimization problem using mixed-integer linear programming. When voltage violations occur rapidly, the smart inverters of PV systems and ESSs help to maintain a lower voltage profile every second based on the proposed piecewise droop control functions at the local level. A simulation study is carried out in an IEEE 33-bus distribution system with an OLTC, CBs, PV systems, and ESSs, and our results demonstrate the advantages of the proposed approach in terms of voltage level and energy savings. Furthermore, the impact of demand reduction on the proposed approach is quantified, and we verify that a higher demand reduction yields more energy savings in the proposed framework.

Concerns about climate changes and environmental air pollution are leading to the adoption of new technologies for transportation, mainly based on vehicle electrification and the interaction with smart grids, and also with the introduction of renewable energy sources (RES) accompanied by energy storage systems (ESS). For these three fundamental pillars, new power electronics technologies are emerging to transform the electrical power grid, targeting a flexible and collaborative operation. As a distinctive factor, the vehicle electrification has stimulated the presence of new technologies in terms of power management, both for smart homes and smart grids. As the title indicates, this book chapter focuses on the role of off-board EV battery chargers in terms of operation modes and contextualization for smart homes and smart grids in terms of opportunities. Based on a review of on-board and off-board EV battery charging systems (EV-BCS), this chapter focus on the off-board EV-BCS framed with RES and ESS as a dominant system in future smart homes. Contextualizing these aspects, three distinct cases are considered: (1) An ac smart home using separate power converters, according to the considered technologies; (2) A hybrid ac and dc smart home with an off-board EV-BCS interfacing RES and ESS, and with the electrical appliances plugged-in to the ac power grid; (3) A dc smart home using a unified off-board EV-BCS with a single interface for the electrical power grid, and with multiple dc interfaces (RES, ESS, and electrical appliances). The results for each case are obtained in terms of efficiency and power quality, demonstrating that the off-board EV-BCS, as a unified structure for smart homes, presents better results. Besides, the off-board EV-BCS can also be used as an important asset for the smart grid, even when the EV is not plugged-in at the smart home.

Over the last few decades several innovative ideas have been explored in the energy storage areas, ranging in size, capacity, design complexity, and targeted applications. Some of them are designed for large scale power system applications, others for smallor medium-scale renewable energy or hybrid power systems, while the others are designed to perform short-term energy storage ride through for critical infrastructure (communication systems, hospitals, military facilities, etc.). Energy storage has become an enabling technology for renewable energy applications, grid integration and enhancing power quality and stability in the power transmission and distribution, having a great potential to improve power grid quality and stability and to provide an alternative to fossil fuel-based energy generation. The major constraints for renewable energy penetration are the availability, intermittency, and variability, which can be addressed through energy storage. The energy storage choice depends on specific usage requirements, often incorporating several energy storage systems in order to increase system reliability, capacity, and supply security. In the electric power system, the renewable energy promise lies in its potential to increase grid efficiency, reliability, or in optimizing power flows and supporting variable power supplies. The parameters used in comparisons of various energy storage technologies include efficiency, energy capacity and density, run time, costs, system's response time, lifetime in years and cycles, self-discharge, and maturity of each energy storage technology. The most common energy storage technologies include compressed air, pumped hydro, batteries, fuel cells, flywheels, and super-capacitors. The last four are suitable for the medium scale applications. The chapter discussed energy storage technologies and gives an up to date comparative summary of their performances. After completing this chapter, the readers are able to understand the role, importance, configurations and topologies of energy storage systems, operation principles, characteristics, performances, and operation of major energy storage systems used in power systems, buildings, and industrial facilities. Another benefit is that readers are able to understand the critical role and necessity of energy storage systems in power and renewable energy systems, the differences between large-, mediumand small-scale energy storage systems, and how a system is selected on specific applications based on system characteristics and performances. Major energy storage technologies discussed in this chapter are compressed air energy storage, pumped hydropower storage systems, batteries, flywheels, hydrogen energy storage, fuel cells, supercapacitors, and superconducting energy storage systems. Thermal energy storage systems are covered in detail in the next chapter. This chapter provides comprehensive reviews of the energy storage technologies and gives an up to date comparative summary of their performances, characteristics, and applications.