A review of microgrid development in the United States – A decade of progress on policies, demonstrations, controls, and software tools

Microgrids have become increasingly popular in the United States. Supported by favorable federal and local policies, microgrid projects can provide greater energy stability and resilience within a project site or community. This paper reviews major federal, state, and utility-level policies driving microgrid development in the United States. Representative U.S. demonstration projects are selected and their technical characteristics and non-technical features are introduced. The paper discusses trends in the technology development of microgrid systems as well as microgrid control methods and interactions within the electricity market. Software tools for microgrid design, planning, and performance analysis are illustrated with each tool's core capability. Finally, the paper summarizes the successes and lessons learned during the recent expansion of the U.S. microgrid industry that may serve as a reference for other countries developing their own microgrid industries

Demand and Storage Management in a Prosumer Nanogrid Based on Energy Forecasting

Energy efficiency and consumers' role in the energy system are among the strategic research topics in power systems these days. Smart grids (SG) and, specifically, microgrids, are key tools for these purposes. This paper presents a three-stage strategy for energy management in a prosumer nanogrid. Firstly, energy monitoring is performed and time-space compression is applied as a tool for forecasting energy resources and power quality (PQ) indices; secondly, demand is managed, taking advantage of smart appliances (SA) to reduce the electricity bill; finally, energy storage systems (ESS) are also managed to better match the forecasted generation of each prosumer. Results show how these strategies can be coordinated to contribute to energy management in the prosumer nanogrid. A simulation test is included, which proves how effectively the prosumers' power converters track the power setpoints obtained from the proposed strategy.Spanish Agencia Estatal de Investigacion ; Fondo Europeo de Desarrollo Regional

Data-driven, metaheuristic-based off-grid microgrid capacity planning optimisation and scenario analysis: Insights from a case study of Aotea-Great Barrier Island

Small privately-purchased off-grid renewable energy systems (RESs) are increasingly used for energy generation in remote areas. However, such privately-purchased stand-alone RESs are often unaffordable for households with lower incomes. While considerable attention has been devoted to a range of off-grid microgrid sizing methods, leveraging the potential of data-driven, artificial intelligence-based metaheuristic optimisation algorithms is less well-explored. Importantly, data-driven metaheuristics have the potential to produce the nearest solution to the globally optimum solution in microgrid sizing applications, which have been recognised as non-deterministic, polynomial time-hard (NP-hard) problems. Furthermore, there is a general lack of electrified transportation interventions considered during long-term grid-independent microgrid planning phases. In response, this paper introduces a novel metaheuristic-based strategic off-grid microgrid capacity planning optimisation model that is applicable to associated integrated energy and e-mobility resource plans. The formulated general off-grid microgrid sizing model is solved using a competitively selected state-of-the-art metaheuristic, namely moth-flame optimisation. To test the effectiveness of the proposed model, three independent microgrid development projects have been considered for three communities residing on Aotea-Great Barrier Island, namely Tryphena, Medlands, and Mulberry Grove. The sites of interest have different demand profiles and renewable energy potentials, with consequent changes in the technologies considered in the associate candidate pools.Comment: Electricity Engineers' Association (EEA) Conference 2022, Hamilton, New Zealand, 19-21 September 202

Evolution of microgrids with converter-interfaced generations: Challenges and opportunities

© 2019 Elsevier Ltd Although microgrids facilitate the increased penetration of distributed generations (DGs) and improve the security of power supplies, they have some issues that need to be better understood and addressed before realising the full potential of microgrids. This paper presents a comprehensive list of challenges and opportunities supported by a literature review on the evolution of converter-based microgrids. The discussion in this paper presented with a view to establishing microgrids as distinct from the existing distribution systems. This is accomplished by, firstly, describing the challenges and benefits of using DG units in a distribution network and then those of microgrid ones. Also, the definitions, classifications and characteristics of microgrids are summarised to provide a sound basis for novice researchers to undertake ongoing research on microgrids

Review of trends and targets of complex systems for power system optimization

Optimization systems (OSs) allow operators of electrical power systems (PS) to optimally operate PSs and to also create optimal PS development plans. The inclusion of OSs in the PS is a big trend nowadays, and the demand for PS optimization tools and PS-OSs experts is growing. The aim of this review is to define the current dynamics and trends in PS optimization research and to present several papers that clearly and comprehensively describe PS OSs with characteristics corresponding to the identified current main trends in this research area. The current dynamics and trends of the research area were defined on the basis of the results of an analysis of the database of 255 PS-OS-presenting papers published from December 2015 to July 2019. Eleven main characteristics of the current PS OSs were identified. The results of the statistical analyses give four characteristics of PS OSs which are currently the most frequently presented in research papers: OSs for minimizing the price of electricity/OSs reducing PS operation costs, OSs for optimizing the operation of renewable energy sources, OSs for regulating the power consumption during the optimization process, and OSs for regulating the energy storage systems operation during the optimization process. Finally, individual identified characteristics of the current PS OSs are briefly described. In the analysis, all PS OSs presented in the observed time period were analyzed regardless of the part of the PS for which the operation was optimized by the PS OS, the voltage level of the optimized PS part, or the optimization goal of the PS OS.Web of Science135art. no. 107

Optimal sizing and operation planning of microgrids and operation analysis of charging stations for electric vehicles

Premi Extraordinari de Doctorat, promoció 2018-2019. Àmbit de les TICEnergy and transportation sectors are going through major changes as a result of technological advances, depletion of fossil fuels and climate change. With regard to the energy sector, the future smart grid is expected to be an interconnected network of small-scale and self-contained microgrids, in addition to a large-scale electric power backbone. By utilizing microsources, such as renewable energy sources, energy storage systems and vehicle-to-grid systems, microgrids target to satisfy the customers’ energy demands in a safe, reliable, economic and environmentally friendly way. With regard to the changes in the transportation sector, internal combustion engine vehicles are expected to be gradually replaced by electric vehicles, which are considered to be a promising solution for mitigating the impact of transportation sector on the environment. The presented thesis deals with two main topics; the first one refers to the optimal sizing and operation planning of microgrids comprising various urban building types, while the second one is related to the operation of fast charging stations for electric vehicles that are located in densely populated areas. The first objective of the thesis is to examine the effect of energy exchanges among interconnected buildings with diverse load profiles on the sizes of power equipment to be installed at the buildings. To this end, a mixed integer linear programming optimization framework is presented that determines the optimal capacities of photovoltaic panels, energy storage systems, and inverters, as well as the optimum management of the generated power. As a first step, the benefits of cooperation among buildings that are already interconnected through an existing point of common coupling is examined. The cooperation benefits are derived by comparing the buildings' costs when they participate in the microgrid with their costs when they operate as separate entities. As a second step, a different microgrid topology is proposed where energy exchanges take place through a common DC bus. In this way, neighboring buildings that are not already physically connected can be members of the same microgrid. Moreover, the optimization results for the new topology are obtained by using the Nash bargaining method, through which the benefits of cooperation are equally distributed among the participating members. Finally, the possible integration of new buildings in the existing microgrid at a later time point is also examined. The second objective of the thesis is to provide an accurate operation analysis of fast charging stations for electric vehicles. To this end, a novel queuing theory-based model is presented that classifies the various electric vehicles by their battery size. As a first step, it is analyzed a charging station that contains DC outlets, and the electric vehicles recharge their batteries up to the maximum possible level. The proposed model takes into account the arrival rates and state of charge of the electric vehicles' batteries when arriving at the station, in order to compute the maximum number of customers that can be served, subject to an upper bound for the waiting time in the queue. In addition, a charging strategy is proposed, which allows the charging station to serve more customers without any increase in the queue waiting time. As a second step, it is considered that the charging station can serve both DC and AC electric vehicle classes, while a more flexible way is adopted for denoting the customers' recharging patterns. Based on these additional novelties, the overall profit margin of the charging station operator, and the queue waiting times of the DC and AC classes are calculated under two different pricing policies.Award-winningPostprint (published version

Optimal Design and Operation Management of Battery-Based Energy Storage Systems (BESS) in Microgrids

Energy storage systems (ESSs) can enhance the performance of energy networks in multiple ways; they can compensate the stochastic nature of renewable energies and support their large-scale integration into the grid environment. Energy storage options can also be used for economic operation of energy systems to cut down system’s operating cost. By utilizing ESSs, it is very possible to store energy in off-peak hours with lower cost and energize the grid during peak load intervals avoiding high price spikes. Application of ESSs will also enable better utilization of distributed energy sources and provide higher controllability at supply/demand side which is helpful for load leveling or peak shaving purposes. Last but not least, ESSs can provide frequency regulation services in off-grid locations where there is a strong need to meet the power balance in different operating conditions. Each of the abovementioned applications of energy storage units requires certain performance measures and constraints, which has to be well considered in design phase and embedded in control and management strategies. This chapter mainly focuses on these aspects and provides a general framework for optimal design and operation management of battery-based ESSs in energy networks

Microgrids/Nanogrids Implementation, Planning, and Operation

Today’s power system is facing the challenges of increasing global demand for electricity, high-reliability requirements, the need for clean energy and environmental protection, and planning restrictions. To move towards a green and smart electric power system, centralized generation facilities are being transformed into smaller and more distributed ones. As a result, the microgrid concept is emerging, where a microgrid can operate as a single controllable system and can be viewed as a group of distributed energy loads and resources, which can include many renewable energy sources and energy storage systems. The energy management of a large number of distributed energy resources is required for the reliable operation of the microgrid. Microgrids and nanogrids can allow for better integration of distributed energy storage capacity and renewable energy sources into the power grid, therefore increasing its efficiency and resilience to natural and technical disruptive events. Microgrid networking with optimal energy management will lead to a sort of smart grid with numerous benefits such as reduced cost and enhanced reliability and resiliency. They include small-scale renewable energy harvesters and fixed energy storage units typically installed in commercial and residential buildings. In this challenging context, the objective of this book is to address and disseminate state-of-the-art research and development results on the implementation, planning, and operation of microgrids/nanogrids, where energy management is one of the core issues