What is a microgrid system?

Author:BSLBATT    Publish Time: 2021-03-21

A microgrid is a self-contained energy system that serves a discrete geographical footprint, allowing you to generate your own power on site and use it when you need it most. Examples include university campuses, hospital complexes, business centres or communities.

 

Microgrids have one or more distributed energy sources that generate energy (solar panels, wind turbines, combined heat and power, generators). In addition, many of the newer microgrids contain energy storage, usually by batteries. Some now also have charging stations for electric vehicles. Based on this structure, you can operate the microgrid while connected to the utility grid or in a disconnected 'island' mode.

 

It is important to note here what is not a micro-grid. Some people use the term to describe simple distributed energy systems, such as rooftop solar panels. A key difference is that the microgrid will keep the power flowing in the event of a central grid failure. Solar panels alone will not. Many homeowners with solar panels are unaware of this fact and, accidentally, they lose power during grid outages. In addition, a simple back-up generator is not a micro-grid. Such systems are only used in emergency situations.


 electrical grids


We can learn about microgrids by looking at three characteristics.


1. Layout in the vicinity of the place of use of electricity

Firstly, it is a localised energy source, which means it creates energy for nearby customers, unlike the large central grid that provides us with most of our shops. The central grid pushes the power from the power plant over long distances via transmission and distribution lines. Long-distance power supply is inefficient, as eight to 15 per cent of it is dissipated during transport. Microgrids overcome this inefficiency by generating power close to the power they serve. Generators are located near or inside buildings, or on the roofs of solar panels.


2. Independent of the central grid

Secondly, microgrids can be disconnected from the central grid and operate independently. This islanding capability allows them to supply power to customers in the event of a storm or other disaster that disrupts the grid. In the USA, central grids are particularly vulnerable to outages due to their sheer size and interconnectedness - more than 5.7 million miles of transmission and distribution lines. As in the Northeast blackout of 2003, a single tree falling on a power line can destroy power in several states and even across the international border with Canada. Through islanding, microgrids can avoid such cascading grid failures.

Although microgrids can operate independently, most of the time they usually remain connected to the central grid (unless they are located in remote areas where there is no central grid or where they are unreliable). As long as the central grid is functioning properly, the two functions work in a symbiotic relationship, as described below.


3. Resources can be intelligently controlled

Thirdly, microgrids provide intelligent control over the distribution of resources, especially if they are equipped with advanced systems. This intelligence stems from the microgrid controller, the central brain of the system, which manages the generators, batteries and energy systems of nearby buildings with a high degree of sophistication. The controller programs multiple resources to meet the energy goals established by the microgrid's customers. They may be trying to achieve the lowest price, the cleanest energy, the greatest electrical reliability or some other outcome. The controller achieves these goals by increasing or decreasing the use of any of the microgrid's resources (or a combination of these resources), just as a conductor calls on various musicians to raise, lower or stop playing their instruments for maximum effect.

 

Working together through complex algorithms, the resources of a microgrid create a whole that is greater than the sum of its parts. They raise system performance to levels of efficiency that no one else can. All these business processes are managed automatically and in an almost instantaneous manner. No human intervention is required.

 

Microgrids have been around for decades, but it is only recently that their reliability has become more widely known. Due to climate change, ageing infrastructure, cyber-attacks and other threats, the pace of installation of microgrids will gradually accelerate and is expected to increase considerably in the future as the price of distributed energy decreases and concerns about power reliability intensify.


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