One of the major problems with ROCOF measurements is the large spike in the output of a ROCOF instrument when a so-called ‘phase jump’ occurs on the power network. As the name suggests these are sudden step in phase lasting perhaps a few cycles that do not represent a real change of the power system frequency.

Phase steps have a number of causes related to faults and switching events in power networks. A new algorithm has been developed by the project team to attempt to ‘ride-through’ phase jumps by using the trajectory of the underlying frequency. This is currently being tested in 6 PMUs installed on Bornholm Island in Denmark. This algorithm was presented at the conference for precision electromagnetic measurements in Paris in July 2018. We hope it will be published as a peer reviewed paper in the near future.