Island mode refers to a site that is able to operate independently of the grid, through the use of a smart microgrid. While microgrids typically operate with a grid connection, they are designed to be able to switch to ‘island mode’ and continue operating when there is a disruption to grid supply. Once in island mode, these microgrids are designed to have enough on-site generation capacity that they can continue to support operations indefinitely.
Island mode for a site may be manual or automatic. For manual island mode, once grid power is lost a site will have to manually start up their emergency generation systems and transition critical loads to this backup power. For large sites, this process can take up to an hour, and often will require active management and prioritising of key loads.
Manual island mode capabilities are generally much lower cost as they do not usually incorporate enough on-site generation to support operations indefinitely. Instead, they are used to allow a site to shut down safely and without damage to equipment in the case of a major power outage.
Automatic island mode is much quicker to switch to and, does so automatically. However, it requires a much more complex energy infrastructure to implement, as well as an intelligent energy management system to manage loads automatically. It also requires on-site generation capable of meeting both base load and peak loads for the site.
Seamless transition refers to an automatic island made capable of switching without any disruption, usually before employees would even be aware of a disruption. Programmable logic controllers are used to achieve this, opening and closing the required circuit breakers remotely.