Can a cogeneration unit operate without connection to the grid?
Islanding (that is, the ability to operate the cogeneration plant in total isolation from the electricity grid) is a feature that many customers would find attractive; however, it is often technically complex to deliver. To effectively implement islanding, the cogeneration plant has to be designed to rapidly respond to load demand, meet voltage and frequency requirements and sustain generation plant stability. These requirements are different from the normal arrangements that would call for the co-generator to disconnect when substation supply is lost. The stability of the cogeneration plant requires complex control systems to quickly reduce the plant output during the transition to islanded operation. An alternative to the islanding option is partial islanding. In this case, a ‘non-critical’ section of the plant is isolated from the main system with the supply for this section provided by a dedicated generator. As this system is electrically isolated from the remainder of the internal
