Do you know what happens in the electricity network during island operation? To establish an island operation, both technical and regulatory conditions are needed. Examples of technical conditions are the need for island production, an electricity grid adapted for island operation and the possibility of black start of the grid. All network owners want to be able to ensure that they do not have undesired island operation.
In the event of undesired island operation, customers can be affected by both voltage and frequency levels that are not desirable. In addition, the network’s protection system is often not adapted for this operating condition, which can negatively affect the ability to disconnect faults.
The possibility of island operation also affects the role of the grid owner. For example, it is not enough to disconnect the connection to the overhead network to safely de-energise the distribution network and carry out repairs and maintenance.
You must also first ensure that all distributed generation units are disconnected, so that they do not energise power lines and pose a danger to repair personnel.
Unipower has developed a tool to better control what happens in the grid during frequency deviations. The example in the diagram is from 12 January 2023 when Nordlink tripped with 1200 MW import and successful start-up of 6 gas turbines in Sweden.
Everything went well with only a minor voltage drop, which, however, was visible over large parts of Sweden. With Unipower’s Continuous Scan function, you can follow detailed progress over longer periods, which provides a very powerful tool for controlling settings and how different production facilities affect each other.