Report with data for system behaviour at storm passage with original (uncoordinated) and coordinated control: Deliverable no: 12.2

In this report the focus has been on explaining the operational procedures that are important in order to maintain balance in the electricity system to understand how unexpected events are handled. The unexpected events discussed in this demo are sudden unexpected loss of wind power production due to stormy weather conditions. When handling the system it is important both to have good forecasts of wind power production so that the wind power production can be anticipated as precise as possible as early as possible so that regulating power can be activated to restore the anticipated balance. In addition it is important to have access to enough automatic restoration reserves to restore balance when unanticipated deviations from schedules occur. What the trade-off between these two types of reserves should be is an on-going discussion.
During the duration of the project, several high wind speed events were recorded at Horns Rev 2, with both the High Wind Shut Down (HWSD) controller and the High Wind Ride Through™ (HWRT) controller which was developed in this project. The analysis presented in this report has shown that when the wind turbines are equipped with HWRT, the maximal wind power forecast error decreases with more than 50%. Similarly, the energy production during the high wind events increased with the HWRT controller compared to the HWSD controller, although the amounts are negligible compared to the yearly production.
The storm front event on February 7th -8th, 2011, which was followed by the unexpected failure on HVDC line between Western Denmark and Sweden, illustrates the consequences and challenges the power system faced/will face in the future when these events (will) occur. The measured values indicate that the large part of the imbalances caused by storm is compensated by exchanged balancing power, activated from the NOIS list, across Konti-Skan link. This shows the pivotal role of hydro power in the Nordic system to balance large wind power variations in Western Denmark especially during the storm events. However, the frequency in the Nordic system experienced large deviations due to large deviation on exchange across Konti-Skan link.