I have analysed a little bit regarding the definition of a microgrid and its all related challenges in details. After analysing the existing definitions, I have come to the conclusion that a control unit needs to be included in the definition of a microgrid, otherwise, it is not appropriate to me.
I have revised the definition as follows.
“A microgrid (consisting of small-scale emerging generators, loads, energy storage elements and control units) is a controlled small-scale power system that can be operated in an islanded and/or grid-connected mode in a defined area to facilitate the provision of supplementary power and/or maintain a standard service.”
Remark: The term ’and/or’ is added to the microgrid definition to include all types of microgrids, for example, islanded and grid-tied ones. ’And’ does not cover an islanded microgrid due to its lack of grid-connection facilities whereas ’or’ refers to one mode of a microgrid operation, i.e., either grid-tied or islanded.
If you are interested in the topic, please download the paper in the following link
https://www.preprints.org/manuscript/201810.0278/v1
Title: Evolution of Microgrids with Converter-Interfaced Generations: Challenges and Opportunities
Authors: Md Alamgir Hossain, Hemanshu Roy Pota, Md Jahangir Hossain and Frede Blaabjerg
It will be my pleasure to discuss about the topic.
N.B: The definition was previously published in "Energies" journal titled "Overview of AC Microgrid Controls with Inverter-Interfaced Generations". https://www.mdpi.com/1996-1073/10/9/1300
Authors: Md Alamgir Hossain, Hemanshu Roy Pota, Walid Issa and Md Jahangir Hossain
On the definition of microgrid, you may also be interested to give a look to this publication: Article Off-grid systems for rural electrification in Developing Cou...
According to DoE, microgrid is a group of interconnected loads and distributed energy resources with clearly defined electrical boundaries that acts as a single controllable entity with respect to the grid and can connect and disconnect from the grid to enable it to operate in both grid connected or island mode.|
Another definition can be found in Whatis.com:
A microgrid is a small-scale power grid that can operate independently or collaboratively with other small power grids. The practice of using microgrids is known as distributed, dispersed, decentralized, district or embedded energy production.
Any small-scale, localized power station that has its own generation and storage resources and definable boundaries can be considered a microgrid. If the microgrid can be integrated with the area's main power grid, it is often referred to as a hybrid microgrid.
@ Jorge Morales Pedraza
Thank you very much for your answer. I have the following question.
According to the definitions, there are no islanded micorgrids that are located in remote areas or islands. In addition, the purposes of constructing a microgrid is missing in the definition.
Who will enable a microgrid to be operated as a single controllable unit? Is the process a part of a microgrid or control units or anything else?
Moreover, the definition mentions every microgrid should be connected to the grid utility. Is it the case?
Therefore, I have revised a microgrid's definition to cover the missing parts of the microgrid definition.
My answers to your questions are the following:
1- According to the definition of microgrid it acts as a single controllable entity with respect to the grid and can connect and disconnect from the grid to enable it to operate in both grid connected or island mode. A microgrid generally operates connected to the grid, but importantly, it can operate independently using local energy generation, batteries, and/or renewable resources like solar panels.
2- One thing is the definition of microgrid and another thing is the purpose of such grid. The purpose to a microgrid is to provide electricity to remote or isolated areas or in any other cases in which electricity cannot be provided by the electrical grid.
Jorge Morales Pedraza
According to the microgrid definition you mentioned, you will find to see a microgrid definition in literature and books by many researchers that "A Micro-Grid is a small-scale power system that consists of a group of interconnected loads and Distributed Generators (DG)."
My question is: how much is the definition accurate?
It neither follows a standard definition nor maintains a good definition, leading a misuse of the microgrid term.
There is no unique acceptable definition of the term microgrid. However, all of them have the following ideas:
1- A microgrid can be connected to the electrical grid or can be used independently of the electrical grid.
2- The main purpose of a microgrid is to supply electricity to isolate or remote areas or to areas where the electrical grid can not be used to supply electricity.
3- The capacity of the grid is very small.
According to my understanding. Md. Alamgir Hossain A microgrid is a well-disciplined system that comprises multiple distributed conventional and renewable power generation sources. It emphasizes on the construction of durable and proficient power system, which is capable of supporting distribution generation and allows much higher penetration levels of renewable energy generation hence cutting down on the requirement of a high voltage transmission and distribution system.
Sheeraz Iqbal Thank you very much for your replying. My understanding regarding a definition is that it will be written within one sentence that describes its unique identities/features. A definition can be defined from different perspectives, such as physical meaning, constructional meaning, descriptive meaning or others. Now judge yourself which one you want to choose to write a microgrid's definition.
In your definition, you mentioned conventional and renewable sources. If conventional sources are not used in a small power system after maintaining all the qualities, it will not be a microgrid according to your definition! Think critically, you will find a proper answer.
In my opinion, for the definition of a micro-grid system it is not necessary to include control, because if the micro-network is isolated, its inclusion is not necessary.
Carlos Cervantes Thanks for your comments.
I think, it is not necessary to consider all sort of small-scale power systems to be considered as a microgrid unless it has a control system over the defined region. For example, when a diesel generator is supplying power to one, two or more houses, we can not tell it is a microgrid but can define as a small-scale power system. This types of power system is operated around the globe since the evolution of a power system. The term 'microgrid' is related to the modern power generation system; therefore, we need to distinguish the term 'microgrid' from conventional small-scale power systems.
Basically, the control unit will define the specific area of the microgrid to operate effectively and efficiently. A control unit is employed for facilitating the system’s features, such as seamless transfer, and working as a supplementary power supply during an islanded operation. Also, a central control unit is essential to obtain second-to-second power balance and optimal use of a microgrid's components.
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