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In general, microgrids (MGs) can be described as integrated systems composed of distributed energy resources and electrical loads operating as a single, autonomous network, in parallel or “islanded” from the distribution network. Smart microgrids are small, modern systems that mimic to a lesser extent today’s large centralized electrical system. Similar to large electrical power systems (EPS), microgrids can generate, distribute, and regulate the flow of electricity to consumers. When operating in parallel, microgrids increase the main grid capacity, reliability, and efficiency. MGs are designed to provide reliable and efficient electricity to small communities, facilities, or even individual homes, and can be powered by a variety of energy sources, such as solar panels, wind turbines, diesel generators, or batteries. Energy storage systems are usually included to ensure security (possibility of islanded operation), reliability, and controllability. A microgrid can be formed by a decentralized group of electricity sources and loads that normally operates connected to a Smart grid or classic grid distribution infrastructure.
- connection and operation of microgrids
- microgrids
- mini- and microgeneration
- Standards for Microgrids
- Procedures for Microgrids
- Microgrids Definition, Classification, and Applications
1. Introduction
Microgrids are able to operate even when the main power system is down and can strengthen the grid reliability and help to mitigate grid disturbances, as well as function as a grid resource for faster system response and recovery. Microgrids can also be used to integrate renewable energy sources, such as solar and wind power, into the local electricity supply, reducing dependence on fossil fuels and promoting sustainability. In addition, MGs can help to reduce transmission losses and increase the resilience of the power system, as well as provide greater control and flexibility over the energy supply [1]. Despite the potential benefits, one of the relevant challenges for the implementation of microgrids in several countries, as well as in Brazil, is the absence of consolidated guidelines and standards for operation and connection. One example is the islanded operation. Currently, due to security and stability concerns during the restoration process, the regulatory framework does not allow distributed generators classified as micro/minigeneration to operate in islanded mode. However, some categories of generators, such as self-producers of energy operating in parallel with the grid, can operate islanded from the distribution grid. An adequate standardization can contribute to the development and incorporation of new technologies and even improve the electricity grid through well-structured operating agreements (for example, using microgrids providing support to the grid).
2. Standards for Microgrids and Distributed Energy Sources
Microgrids are equipped with distributed energy resources (DERs)—which include generation and energy storage systems—allocated in a decentralized manner, within the area of a given distribution utility. These resources are connected close to the electrical load (downstream of the PCC—point of common coupling—or located next to consumer units, downstream of the meter—behind-the-meter). In addition to the electrical conventional generation and storage technologies, DERs can use energy efficiency actions, demand-side management strategies, and can include special loads such as electric vehicles with charging stations capable of operating in V2G mode (Vehicle to Grid) [2][3].
In recent years, there has been an acceleration in the insertion of DERs, justified mainly by investment and transaction costs reductions, followed by greater dissemination of telecommunication and control technologies, as well as the more active role of consumers. The recent DERs growth indicates that the diffusion of these technologies has a high disruptive potential [4], capable of profoundly transforming the conventional electrical systems that today are predominantly operated with larger resources and centrally managed [5] to a larger distributed resource and management.
2.1. International Standards IEC and IEEE
The IEEE and the IEC are two of the most accredited international actors for standardization of grid connection and operation of microgrids. As mentioned before, there are two main “families” of standards related specifically to the microgrids: the IEEE 2030 and the IEC 62898. Although the microgrids can be composed of several components that usually would be subject to specific rules or standards (such as PVs and others), the operation of the DERs in a microgrid configuration deserves a specific standardization. Keeping this in mind, the two families and their main points are presented as follows to help to understand the specificities of microgrids. The criteria for grid connection and operation of distributed generation, as well as storage systems, including microgrid controls, the minimum requirements related to power quality (including voltage and frequency levels), regulation capacity of its state variables, and definitions of grid-connected and islanded operation, are all mainly described in the IEEE 2030 and IEC 62898 standards families.
The specific standards from IEEE are: (A) IEEE Standard for the Specification of Microgrids Controllers (IEEE Std 2030.7); (B) IEEE Standard for the Testing of Microgrid Controllers (IEEE Std 2030.8); and (C) IEEE Recommended Practice for the Planning and design of Microgrid (IEEE Std 2030.9). The IEC standard family include: (D) IEC Technical Specification Part 1: Guidelines for Microgrid Projects Planning and Specification (IEC TS 62898-1); and (E) IEC Technical Specification Part 2: Guidelines for Operation (IEC TS 62898-2), those being the most relevant documents internationally accepted.
Associated with Microgrids, DERs allow greater consumer participation in the management of their own energy consumption that is based in their local generation. Broadly speaking, the distributed resources that compose a microgrid include: (i) distributed generation (DG), (ii) energy storage systems (ESS), and (iii) electric vehicles (EV) including their recharge systems. Each type of DER has specific operational characteristics and, depending on the expected impacts or behavior on the distribution network, must apply different requirements to obtain grid permission to connect. Under this context, the technical specifications for interconnection and interoperability tests between electric power systems and DERs are the focus of the IEEE Std 1547-2018—IEEE Standard for Interconnection and Interoperability of Distributed Energy Resources with Associated Electric Power Systems Interfaces.
The IEEE Std 1547-2018 establishes several aspects related to the operation performance criteria; interconnection safety and maintenance considerations; as well as general requirements responding to abnormal conditions, power quality, islanding and test specifications, and requirements for design, production, installation assessment, commissioning, and periodic testing. The IEEE 1547 standard outlines the technical requirements for interconnecting distributed energy resources (DERs), including microgrids, with electric power systems. Additionally, DERs must meet the specific standards of each technology to meet interconnection, interface, and interoperability requirements established in the IEEE 1547-2018. Considering all the analyzed documents, it was verified that, in general, some utilities have been following the guidelines of the IEEE 1547-2018 standard to guide the operating requirements of microgrids [6], while some regions (usually in Europe) have also been adopting requirements in accordance with IEC standards. Figure 1 illustrates the main international standards widely accepted for microgrids.
Figure 1. Standards for microgrids.
2.2. Microgrid Definition, Classification, and Applications
A number of microgrid definitions [7], functional classification schemes [8], and applications [9], as well as technologies and outstanding issues [10], can be found in the literature. A broadly accepted definition according to the U.S. Department of Energy by the Microgrid Exchange Group defines a microgrid as a group of interconnected loads and distributed energy resources within clearly defined electrical boundaries that act as a single controllable entity with respect to the grid that can connect and disconnect from the grid to enable it to operate in both grid-connected or island mode [11].
MGs can be confused with backup generators (diesel genset). However, backup generators generally do not operate permanently in parallel with the grid, are used for short-term emergency power supply, and do not provide seamless transitions in unscheduled outages. On the other hand, MGs combine local assets constituting arrangements of DERs capable of operating autonomously and uninterruptedly (without interruptions even when external disturbances occur in the EPS), and with constant performance monitoring (via EMS).
MGs can be composed of several generation sources and segmented loads in the electrical network. Some of these loads can be critical, such as hospitals, vital equipment on military bases, or sensitive equipment on universities or commercial campuses and industrial plants. Therefore, these types of loads must remain operational even when an interruption occurs in the electrical system. Microgrids can be used as a reliable power source to critical loads [12]. The use of microgrids for military defense facilities are presented in ref. [13] (Alcântara Space Center) and ref. [14] (Pear Harbor case). In these cases, the MG is the primary source to supply to the interconnected loads and is equipped with a control system capable of managing energy and power [15]. The controller, when a dispatchable primary power source is available, enables automated islanding and DER-optimized operation based on decentralized or centralized coordination strategies.
3. MERGE Project Microgrids—Nanogrid, Congrid and Campusgrid—General Definitions and Proposed Regulatory Classifications
Within the scope of the MERGE (Microgrids for Efficient, Reliable and Greener Energy) project, in addition to the development of test laboratory infrastructure (at LabREI—Interdisciplinary Research in Smart Grid Laboratory), three microgrids are in development: nanogrid (a small microgrid limited to a single Consumption Unity—CU), congrid (a condominium microgrid), and Campusgrid (a microgrid with a medium voltage connection and larger load feeding at a university campus), as illustrated in Figure 2.
Figure 2. MERGE (Microgrid for Efficient, Reliable and Greener Energy) project microgrids—Nanogrid, Congrid, and Campusgrid.
Each one of these microgrids types has peculiarities associated with topology, installed power, and application. Figure 3 illustrates the conceptual model of a nanogrid proposed in the MERGE project, which is characterized by the presence of a DC bus and, in the reference topology, contains the following elements: (1) distributed microgeneration (DG); (2) energy storage system (ESS); (3) vehicle charging station; and (4) converters and integration subsystems. The nanogrid is ideally formed so that the sum of the installed loads/generation does not exceed the limit for connecting installations in the low voltage distribution system (LVDS).
The MERGE congrid microgrid aims to implement a pilot for a set of residential loads, taking the concept to the local utility consumers. In principle, the objective is to design and implement the microgrid in a place characterized as a residential condominium, which would integrate the generation, storage, and management technologies, being able to operate in a connected mode with the distribution network or islanding (forced or intentional). The congrid concept is similar to a community microgrid [16]. However, the main microgrid’s equipment (such as the energy storage system) are owned and operated by the energy distribution company/utility.
Currently, the Campusgrid microgrid is under implementation at Cidade Universitária Zeferino Vaz, at Unicamp/Campinas (São Paulo/Brazil) [17]. The maximum possible resilience has been stated as one of the main requirements. Thus, in the face of disturbances that affect the operation of the distribution network, total or partial attendance of the load is expected. Campusgrid can operate connected to the concessionaire’s main grid or in an islanded way, with the possibility of exporting the surplus in the first case. When in islanded mode, in addition to the sources that will provide the microgrid, the energy storage systems and other dispatchable sources will be used to mitigate interruptions and maintain the safe and proper operation of Campusgrid.
Although academically the concept of microgrids is solid and widely accepted, one of the challenges is to overcome the adequate framing of customer units (CUs) equipped with microgrids and the consolidation/convergence of normative definitions for different microgrid categories in Brazil. Since Brazilian standards impose requirements on connection and operating conditions depending on the installed capacity and voltage level, the following topics present a proposal for structuring/categorizing microgrids, with the appropriate definitions, classified by the regulatory load and voltage limits that are imposed by ANEEL’s Normative Resolution n° 1000 (of 7 December 2021) [18].
Figure 3. Schematic single line diagram. (a) Nanogrid and its DERs, with AC coupling; (b) generic scheme of a Campusgrid microgrid. Adapted from CPFL Utility Technical Requirements GED 13 [19].
Article 23 of the ANELL REN n° 1000 addresses the framework of the Supply Voltage of consumer units according to their installed capacity and the contracted demand: I—low voltage in the aerial network, when the installed capacity in the consumer unit is equal to or less than 75 kW; II—primary distribution (medium) voltage lower than 69 kV, when the installed capacity (in the consumer unit) is higher than 75 kW and the demand to be contracted by the interested party, for the supply, is equal to or lower than 2500 kW; and III—primary distribution voltage equal to or greater than 69 kV when the demand to be contracted by is greater than 2500 kW. Using the established regulations and taking into account the technical aspects consolidated in the literature and the normative framework, three general categories of microgrids can be established: (1) nanogrids, (2) condominium microgrids, and (3) campus microgrids.
4. Critical Aspects for Standardization
The main difference between the use of microgrids and the simple integration of distributed generation units to the distribution networks is the possibility of operation in both interconnected and islanded modes [20].
The operation of a microgrid can then be divided into three modes: grid connected, islanded (or autonomous operation), and synchronization/reconnection (transient modes). The main operating modes for microgrids, according to ref. [21], are illustrated in Figure 4.
Figure 4. Operating modes allowed in operating procedures for microgrids—considering the PRODIST requirements.
4.1. Operation Modes—Grid Connected Operation (Parallel Operation)
The grid connected operation mode (also known as parallel operation) occurs when the microgrid locally produces alternating current power while electrically connected to the local utility’s distribution grid. In this condition, the microgrid must have voltage and frequency values compatible with those of the distribution network [22]. It must also meet the minimum power quality requirements, as well as not interfere with the protection and reliability functions of the distribution utility. Parallel operation can be divided in two cases: the first, all the energy produced is consumed by the customer’s load (so called non-export), and the second case are those in which part of the local produced energy is exported to the utility’s distribution system (so called export). The export is defined in relation to the point of common coupling (PCC). In most cases, it is demarcated by the energy meter; however, it may be associated with a service transformer, a disconnector switch, or some other equipment, as defined by the distribution utility.
4.2. Operation Modes—Islanded Mode Operation and Synchronization
One of the most important features of a microgrid relies on its ability to operate in both grid-connected and islanded mode, automatically shifting modes. When the microgrid operates in grid-connected mode, the main grid sets the operating conditions for voltage levels and frequency; conversely, in islanded mode, voltage and frequency are determined by the internal control system using their DERs, and therefore an appropriate control scheme is necessary to ensure stable and resilient operation [22].
In modern MG applications, with the potential of autonomous operation, a fast and reliable detection algorithm is required to effectively distinguish between an islanding condition and other types of disturbances. A comprehensive analysis of microgrid autonomous operation during and after the islanding process, the control strategies and algorithms required for maintaining system stability and power quality during islanding, and the challenges associated with islanded microgrid operation is presented in ref. [12].
The IEEE Std 1547.4-2011 standards provides approaches and practices for design, operation, and integration of distributed resource island systems with electric power systems (EPS). This includes the ability to separate from and reconnect to part of the area EPS, while providing power to the islanded local EPSs [23].
According to the IEC 62898 standard, the microgrid can go into islanding mode when: (i) the power quality and stability requirements are not fully met by the main grid (to protect internal equipment and maintain its integrity), and (ii) when requested by the distribution system operator. This operator can benefit from the inclusion of microgrids (MGs) in the main grid, as it can consider them as “flexible loads” (or even “flexible generation”, depending on the direction of energy flow exchange), leading to a strategy called demand side management. This means that these loads can be disconnected whenever necessary (e.g., in the event of a contingency) and reconnected under normal grid conditions without serious economic and social impacts. In addition, the day-ahead profile for energy demand or MG generation dispatch can be configured according to pre-defined agreements between the distribution system operator and the MG operator [24].
The transition to island operation can occur as a result of a permanent main grid failure or due to an intentional disconnection. In the case that the transition is unsuccessful (for example, due to a failure during the transition), the loads are switched off; in this case, the black-start strategy for the MGs must be deployed.
The last mode of operation is the synchronization mode. This is considered a transient mode since it is basically related to the transition from the grid connected to island operation and vice versa. During this procedure, it is imperative to pay particular attention to the transition of the grid references (voltage and frequency). The voltage reference and frequency must be taken by the local DER through speed sensors and action so that there is no discontinuity of local supply. The process to synchronize the MG to the main grid returning from a fault condition is usually simpler when planned, unlike most cases from an abrupt disconnection due to faults. In both cases, it demands specific equipment and control strategies.
4.3. Energy Storage Systems in MG
Due to the variability and intermittency of DG and DERs, it can be difficult to maintain the usual frequency requirements while accommodating load fluctuations, particularly in islanded modes of operation. In this sense, energy storage systems (ESS) play a fundamental role, especially if there is the possibility of continuous parallelism and automatic disconnection from the main grid. Due to the ability to operate as a load or generator (charging or discharging), the use of ESS can mitigate the impact of renewable DG and load variations, ensuring stronger stability and reliability for the microgrid [25].
Some of the requirements for the ESS (when the microgrid is in islanded mode), are as follows: (a) if there is more than one energy storage system, for the one with higher capacity converters, it is recommended to adopt the control in V/f mode (acting as a network former—grid forming function), to establish and maintain the voltage and frequency of the system in isochronous mode, provided that there is no other fast-acting/controllable DER (such as microturbines or diesel generators) used for this purpose; (b) when the output power of the local microgrid’s generation resources are insufficient to meet the demand, the ESS must start the power compensation acting as generation. When the output power of the non-controllable generation resources of the microgrid exceeds the demand of the load, the excess power must be absorbed by the storage system (acting as a load). If the ESS acts as a generation and it is still not possible to meet the power demand safely, the EMS must act on load shedding schemes (load shedding implemented via SPSs (special protection systems) in the electrical bulk system). On the other hand, in the case that the storage is fully charged and there is still some energy surplus, the EMS and DERs will reduce its produced power.
4.4. Proposed Standard for Microgrids PCC (Point of Connection)
The microgrid connection point is deployed to perform automatic islanding (separation or decoupling), synchronization (reconnection), and dispatch controls. Figure 5 illustrates the PoC implemented through a multifunctional relay [26]. The PCC relay can cause automatic islanding by opening a circuit breaker (or recloser). The relay opens the PCC when it detects short circuits, open circuits, or feedback conditions. The relay is configured to distinguish between internal and external disturbances in the system. Opening the PCC provides indications for the microgrid protection and control systems. The PCC trip indication is also used to change relay protection settings across the microgrid to adapt to reduced fault current levels, and can also signal DER control systems to change their operating modes. The interconnection relay must be equipped with protection functions (such as the ANSI 25) to perform the synchronization, automatically dispatching the DERs to reduce the frequency, angle and voltage amplitude differences at the PCC [27]. Once acceptable conditions are identified, the PCC connection switch can be closed again.
Figure 5. Connection structure of a microgrid to the utility distribution system using a protection relay for islanding, with synchronization and dispatch functionality via EMS or DMS.
The protection and controls implemented in the PCC are essential to meet the requirements of the Operating and Connection Agreements. These contracts can define peak power usage, demand charges, generation limitations, frequency and voltage conditions, automatic load reductions initiated by the EPS, protection requirements, and more.
Since most utilities still do not have a standard for microgrid connection, Figure 6 presents a proposed structure (constructive pattern for the concept presented previously in Figure 5), considering a microgrid with a point of connection at medium voltage (up to 34.5 kV). The main idea is the use of signaling to demonstrate the state of operation of the power grid and the microgrid. In the Brazilian case, the standard uses the color pattern of the NR-10 standard (National Rule number 10—item 10.3.9—signaling colors: Red “L” (on-energized) Green “D” (off or de-energized). Additionally, since some microgrids may be equipped with a central control, the info can be displayed through local or remote signaling (via a microgrid monitoring system).
Figure 6. Standard structure proposed for microgrid connection—point of connection at medium voltage, protections implanted using relay and recloser.
4.5. Procedure for Technical Feasibility Assessment of MGs Connection
Due to MGs characteristics, each project is unique, with different DERs sizes and with specific potential impacts on the distribution network. Thus, to maintain safe operation, before effectively connecting a new microgrid to utility grid, a technical feasibility analysis of the connection must be carried out.
It is recommended that the technical assessment for the connection of new microgrids follow the procedures established for generation enterprises, with a four-step process: Phase 1—Connection Consultation; Phase 2—Access Information; Phase 3—Connection Request; and Phase 4—Technical Feasibility Analysis Report, as illustrated in Figure 7.
Figure 7. MGs connection to distribution grid procedure.
4.6. Actors, Management Modes, and Responsibilities
As in conventional electrical power systems, there are structured, well-defined, and segmented functions in sectorial institutions. Similarly, the management and operation functions of microgrids must be properly attributed to the responsible actors. The operation of microgrids with distributed generation units requires a power management strategy (PMS) and an energy management system (EMS) [15]. Adequate EMS modeling can emulate a resilient day-ahead energy market, while minimizing the average operational costs and maximizing the use of local renewable energy sources [28].
For the implementation of operation strategies, a hierarchical level is adopted to establish an operating pattern, in which the following actors are defined: (1) DNO—distribution network operator; (2) DMO—distribution market operator; and (3) MGCO—microgrid central operator (or MCC—microgrid central controller), and (4) LO—local operator, associated with each microgrid generation/load center.
4.7. Protections in Microgrids—Rules to Be Incorporated into Technical Regulations
Since fault current in a microgrid is constantly changing due to the presence of different sources (such as distributed generation DG or BESS) at all levels of the distribution network, and due to the fact that they can operate in islanding and normal modes, designing a proper protection scheme is a serious challenge. Conventional protection methods may be inappropriate; Therefore, special protections schemes have been developed for MGs protection. An overview of microgrid protection methods is presented in ref. [29].
The electrical protection developed for application in microgrids must contemplate a series of requirements when it comes to short-circuit analysis. The microgrid can operate connected to the distribution grid or islanded, and, in both cases, the protection system must be able to sense and act properly so that it does not impact the distribution grid and the microgrid itself. Thus, some points must be considered when defining which protective scheme will be used in the microgrid: (1) in the event of a fault in the distribution grid, the microgrid must be able to operate in an islanded condition in order to preserve the loads within its electrical operation; (2) the microgrid must have the ability to identify and act on faults that occur within its operating network, whether connected to the distribution network or in islanded operation mode; (3) in the case of a microgrid with a high share of distributed generation, it is necessary that the short circuit levels are calculated according to the variation of the share of generation so that the trips of the protection relays are dynamically set to meet the protection requirements; (4) the protection devices must have fast and reliable communication and act according to the operating state of the microgrid; and (5) to ensure short-circuit levels within the operating range of the protective equipment, it is recommended that the microgrid design has a robust energy storage system or system with inverter and/or machine with inertial mechanics to raise current levels during a fault (in order to adequately sensibilize the protection system).
This entry is adapted from the peer-reviewed paper 10.3390/en16062893
References
- Lopes, J.P.; Hatziargyriou, N.; Mutale, J.; Djapic, P.; Jenkins, N. Integrating distributed generation into electric power systems: A review of drivers, challenges and opportunities. Electr. Power Syst. Res. 2007, 77, 1189–1203.
- FGV Energy. Distributed Energy Resources; FGV Energy: Maio, Cabo Verde, 2016.
- Energy Research Company—EPE. Tecnical Report EPE-DEA-NT-016/2018-r0: Distributed Energy Resources (in Portuguese); Ministry of Mines and Energy—MME: Rio de Janeiro, Brazil, 2018.
- Castro, J.F.C.; Marques, D.C.; Tavares, L.; Dantas, N.K.L.; Fernandes, A.L.; Tuo, J.; Medeiros, L.H.A.d.; Rosas, P. Energy and Demand Forecasting Based on Logistic Growth Method for Electric Vehicle Fast Charging Station Planning with PV Solar System. Energies 2022, 17, 6106.
- World Energy Council. World Energy Trilemma; World Energy Council: London, UK, 2017.
- Missouri S&T Microgrid Industrial Consortium. Missouri Microgrid Interconnection Requirements: Prepared for the Missouri Department of Economic; Missouri S&T Microgrid Industrial Consortium: Rolla, MO, USA, 2016.
- Olivares, D.E.; Mehrizi-Sani, A.; Etemadi, A.H.; Cañizares, C.A.; Iravani, R.; Kazerani, M.; Hajimiragha, A.H.; Gomis-Bellmunt, O.; Saeedifard, M.; Palma-Behnke, R.; et al. Trends in Microgrid Control. IEEE Trans. Smart Grid 2014, 5, 1905–1919.
- Martin-Martínez, F.; Sánchez-Miralles, M.R.A. A literature review of Microgrids: A functional layer based classification. Renew. Sustain. Energy Rev. 2016, 62, 1133–1153.
- Shahgholian, G. A brief review on microgrids: Operation, applications, modeling, and control. Int. Trans. Electr. Energy Syst. 2021, 31, e12885.
- Hirsch, A.; Parag, Y.; Guerrero, J. Microgrids: A review of technologies, key drivers, and outstanding issues. Renew. Sustain. Energy Rev. 2018, 90, 402–411.
- Ton, D.; Smith, M. The US department of energy’s microgrid initiative. Electr. J. 2012, 25, 84–94.
- Katiraei, F.; Iravani, M.; Lehn, P. Micro-grid autonomous operation during and subsequent to islanding process. IEEE Trans. Power Deliv. 2005, 20, 248–257.
- Branco, C.C.; Moraes, F.; Oliveira, H.; Neto, P.; Saavedra, O.; de Matos, J.; Oliveira, C.; Ribeiro, L.; Oliveira, A.; Júnior, M.; et al. Mission Critical Microgrids: The Case of the Alcântara Space Center. Energies 2022, 15, 3226.
- Anderson, W. Smart Power Infrastructure Demonstration for Energy Reliability and Security (SPIDERS)—Technology Transition Final Public Report; Joint Capability Technology Demonstration (JCTD)—Naval Facilities Engineering Command: Pearl Harbor, HI, USA, 2015.
- Katiraei, F.; Iravani, R.; Hatziargyriou, N.; Dimeas, A. Microgrid Management—Control and Operation Aspects of Microgrids. IEEE Power Energy Mag. 2008, 6, 54–65.
- Trivedi, R.; Patra, S.; Sidqi, Y.; Bowler, B.; Zimmermann, F.; Deconinck, G.; Papaemmanouil, A.; Khadem, S. Community-Based Microgrids: Literature Review and Pathways to Decarbonise the Local Electricity Network. Energies 2022, 15, 918.
- Quadros, R.; Jucá, J.; Cypriano, J.G.; Silva, R.; Silva, L.; Bento, R. Implementation of Microgrid on the University Campus of UNICAMP-Brazil: Case Study. J. Electron. Adv. Electr. Eng. 2021, 1, 21–25.
- ANEEL—Brazilian Regulatory Agency for Electricity. Normative Resolution No. 1,000—7 December 2021—Establishes the Rules for the Provision of the Public Electric Energy Distribution Service (in Poruguese); MME—Ministry of Mines and Energy: Ministério de Minas e Energia, Brasilia, Brazil, 2021.
- CPFL Energy. Utility Technical Requirements GED13—Supply in Secondary Distribution Voltage (in Portuguese); CPFL Energy: Campinas, Brazil, 2020.
- Lasseter, R.; Akhil, A.; Marnay, C.; Stephens, J.; Dagle, J.; Guttromson, R.; Meliopoulous, A.S.; Yinger, R.; Eto, J.; Integration of Distributed Energy Resources. The CERTS Microgrid Concept. Lawrence Berkeley National Laboratory, 2002. Available online: https://escholarship.org/uc/item/9w88z7z1 (accessed on 12 March 2023).
- Palizban, O.; Kauhaniemi, K.; Guerrero, J.M. Microgrids in Active Network Management-Part II: System Operation, Power Quality and Protection. Renew. Sustai-Nable Energy Rev. 2014, 36, 440–451.
- IEC TS 62898-2; IEC TS 62898-2: Guidelines for Operation. IEC—International Electrotechnical Comission: London, UK, 2018.
- IEEE Std 1547. 4-2011; IEEE Std 1547.4-2011—Guide for Design, Operation, and Integration of Distributed Resource Island Systems with Electric Power Systems. IEEE Standards Association: Piscataway, NJ, USA, 2011.
- Zacharia, L.; Kyriakou, A.; Hadjidemetriou, L.; Kyriakides, E.; Panayiotou, C.; Azzopardi, B.; Borg, N.M.e.N. Islanding and Resynchronization Procedure of a University Campus Microgrid. In Proceedings of the International Conference on Smart Energy Systems and Technologies (SEST), Sevilla, Spain, 10–12 September 2018.
- Gao, D.W. Energy Storage for Sustainable Microgrids; Elsevier: Denver, CO, USA, 2015.
- Manson, S. Industry Perspectives (Schweitzer Engineering Laboratories): Connecting a Microgrid to the Grid; Microgrid Knowledge: Westborough, MA, USA, 2017.
- Edwards, W.; Manson, S. Using Protective Relays for Microgrid Controls; no. TP6824; Schweitzer Engineering Laboratories, Inc.: Pullman, WA, USA, 2018; Volume 20180209, pp. 1–7.
- Silva, J.A.A.; López, J.C.; Arias, N.B.; Rider, M.J.; Silva, L.C.d. An optimal stochastic energy management system for resilient microgrids. Appl. Energy 2021, 300, 117435.
- Hosseini, S.A.; Abyaneh, H.A.; Sadeghi, S.H.H.; Razavi, F.; Nasiri, A. An overview of microgrid protection methods and the factors involved. Renew. Sustain. Energy Rev. 2016, 64, 174–186.
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