Microgrid Methodologies and Emergent Applications

By Chengshan Wang, Tao Xu and Yixin Liu

Microgrid Methodologies and Applications provides step-by-guide guidance on the implementation of microgrids projects that is informed by current scientific principles, emergent technologies such as modern power electronic interfaces, energy storage systems, multi-vector energy systems, and a close study of recent case studies. Addressing the full end-to-end microgrid project lifecycle, the work encompasses planning, design, operation, control, trading and evaluation, with a significant focus on novel business model, regulation and policy considerations. The book explains to readers how they can operationalize robust microgrids which account for engineering reality, uncertainties, and operating constraints.

It delivers precise and rigorous real case studies for project managers, designers and policy and decision-makers. The methodologies section provides step-by-step guidance on implementing projects for postgraduate students, researchers and practitioners, while the applications section provides an array of demonstrative ‘case studies which exemplify the use of optimal methods and leading-edge technologies.

• Provides step-by-step guidance on the design, operation, control, trading and evaluation of microgrid projects
• Demystifies real-world project experience through the evaluation of successful case studies, novel data analysis and comprehensive evaluation rather than cumbersome mathematical formulations
• Combines theoretical and practical insights, serving to bridge gaps between theory and engineering operations, control and decision-making
• Reviews state-of-the-art topics including business models, trading strategies, pricing, regulatory standards and policy recommendations poised to profoundly affect local energy transitions and utilization of microgrids

• Language: English
• Publisher: Academic Press
• Release date: Dec 2, 2023
• ISBN: 9780323953504

Chengshan Wang

Prof. Wang received both his Bachelor’s and Master’s degrees in Geology from Chengdu University of Technology. He is currently a professor of geology at the China University of Geosciences in Beijing. He previously taught geology at Chengdu University of Technology and the Southwest University of Science and Technology, both in China. He was a visiting scholar at the United States Geological Survey and has had fellowships with the Chinese Academy of Sciences and the Geological Society of America. He has authored papers in many top peer-reviewed earth science journals, including Palaeogeography, Palaeoclimatology, Palaeoecology; Earth-Science Reviews; Cretaceous Research; and Gondwana Research.

Book preview

Part I

Methodologies

Outline

1 Overview of microgrid

2 Modeling

3 Planning and design of microgrids

4 Control and protection of microgrids

5 Microgrid operation optimization

6 Energy trading and markets in microgrids

1

Overview of microgrid

Tao Xu,    Key Laboratory of Smart Grid of Ministry of Education, Tianjin University, Tianjin, P.R. China

Abstract

A microgrid is a small-scale self-sufficient energy system consisting of distributed energy resources, energy storage systems and local loads capable of operating in grid-connected or islanded modes. Although the basic concept and principles of microgrids have been brought up for approximate 30 years, increasing attention on research and implementation of microgrids have gained driven by the need to rein in electricity costs, improve resilience and reliability and reduce carbon emissions in recent years. This chapter aims to provide a global overview on the emerging technologies and development of microgrids, the organization and contribution of the book are also presented.

Keywords

Microgrid; operating characteristic; structure characteristic; demonstration project

1.1 Introduction

Modern electric power systems have been designed and operated as a centralized macrogrid, which facilitates the utilization of conventional bulk generation, transmission, distribution, and storage with the power flow feeding from high voltage (HV) to low voltage (LV). Under the framework of Net Zero, the upscaling requirements for greenhouse gas (GHG) emission reduction have highlighted the urgent need for ramping up renewables and boosting the system efficiency. During this unprecedented global energy transition, microgrid (MG) has emerged as a financially viable, reliable, and resilient alternative solution that integrates massive small- to medium-scale distributed energy resources (DERs) while mitigating the fluctuations caused by renewable resources [1].

The basic concept and principles of MGs have been cultivated for approximately 30 years, and it is still evolving with the development of technologies and management systems. Basically, MG is a small-scale, self-sufficient energy system consisting of DERs, energy storage systems (ESSs), and local loads capable of operating in grid-connected or islanded modes. With advanced monitoring, control, and energy management system (EMS), MG can provide reliable, flexible, and resilient energy supply to nearby customers in a certain geographic area, that is, hospitals, university campuses, military sites, islands, etc. Structurally, the MG is composed of energy production, conversion, storage, and utilization components.

1.2 Overview of the key characteristics of microgrid

1.2.1 Operating characteristics

MGs can provide customized power supply services under various scenarios with different components, structures, and operational characteristics.

1. Independent MG on islands or in remote areas: It is problematic and costly to build a conventional power grid on islands or in remote areas. In such cases, a MG can be an attractive and effective solution with bespoke components and structures that meet the requirements of local environmental conditions. For example, the MG can be composed of wind turbines (WTs), photovoltaic (PV) arrays, diesel generators, and batteries in an area with rich wind and solar resources, which is also capable of operating in islanded mode. Although diesel generators are still required in the system due to the uncertainties of wind and solar energy, both annual operating hours and diesel consumption are reduced significantly.

2. Renewable-energy-dominated MG: In areas with abundant solar/wind energy, overvoltage issues may occur if large amounts of solar/wind generation are integrated to the distribution network (DN) directly. Therefore, a renewable-energy-dominated MG at the user or community level can be built to improve the capability of the power grid to accommodate distributed renewable energy. This kind of MG is mainly composed of solar/wind generation and batteries, and usually operates in grid-connected mode. It can also operate in islanded mode under certain circumstances to supply demand independently.

3. MG with diverse energy resources and demands: In areas with abundant energy sources and diverse demands, that is, cooling, heating, electricity, etc., a MG can be constructed to serve public buildings, university campuses, or hospitals. The main purposes of the MG are to integrate with building/community energy saving technologies, improve integrated energy utilization, and realize efficient use of energy. In such MG, electrical energy is generated by solar, wind, geothermal, or biomass energy and stored in electrical or thermal ESSs.

4. DN-integrated MG: As an important part of smart DNs, MG can integrate distributed generators (DGs) into branch level, feeder level, and substation level and the DG units can supply key loads when there are faults in the upstream power grid during disasters and can improve the self-healing capabilities of DNs.

1.2.2 Structural characteristics

There are various types of power sources in the MG, including direct current (DC) power sources such as PVs, fuel cells, and battery energy storage systems (BESSs), as well as alternative current (AC) power sources such as WTs, microgas turbines, and flywheel energy storages. According to the type of busbar, the structure of the MG can be mainly categorized as AC MG, DC MG, and AC/DC hybrid MG. In practical applications, a suitable MG structure can be designed according to specific power source types, load types, and application requirements and various types of distributed power sources and loads can be integrated through corresponding power electronic devices.

1.2.2.1 AC microgrid

Currently, the majority of the MGs are AC MGs where DC resources can connect to the AC busbars via DC/AC converters, and AC resources can be integrated in to the AC busbars using AC/AC (or AC/DC/AC) converters. The schematic diagram of the system topology is shown in Fig. 1.1. And the MG can switch between grid-connected mode and islanded mode using the switch at the point of common coupling