Demonstration project 4 Management of offshore wind power in extreme high wind situations (STORM MANAGEMENT)
- Wind turbine energy output was increased in stormy conditions by using high wind ride through control, which took the cut-off point from wind speeds of 25 metres per second up to 32 metres per second (m/s).
- Using of high wind ride through control reduced the risk of power system instability and blackouts.
Experience from very tough weather conditions in westernduring autumn 2012 demonstrated that if offshore wind turbines are equipped with new high wind ride through control, it is possible to run them for longer during periods with high wind speeds, which means there is less risk of turbine shut-down and less risk to the stability of the power system.
In addition, total output during these periods is higher from turbines equipped with the new high wind ride through control than in those with old control algorithm, which would abruptly shut down thewhen the wind speed went over 25 m/s. Measurements from Horns Rev II during stormy weather proved that the wind turbines equipped with the new high wind ride through control software could stay in operation in wind speeds of up to 32 m/s. The new high wind ride through controllers, developed by (installed on 91 wind turbines at Horns Rev II) leads to less abrupt changes in production for the wind farm as a whole. Wind farms with the new high wind ride through control options will in extreme weather situations experience gradual reductions in production and the mechanical parts of the individual turbine are, generally, less exposed.
In the autumn of 2012, several storms hit western Denmark. During these storms, power production at Horns Rev II hardly went down at all. Simulations show that if the old control algorithm had been in operation, the wind farm would have shut down completely (see figures opposite).
During the autumn 2012 and winter 2012/2013 storms, the extra power production with the new system was considerable. Moreover, if wind speeds are high enough to cause the power produced to decrease, the drop in output happens much more gradually than would have been the case with the old system. This was the case for the big storm on 30-31 January 2013. This is a huge advantage for balancing the electricity system.
The power system in western Denmark is operated as one area that needs to be in balance. Problems occur only rarely thanks to advanced operating systems. Everyone responsible for balancing in the power system in Denmark is obliged to update their detailed production and consumption schedules every five minutes. The detailed schedules provide Energinet.dk (the Danish TSO) with the opportunity to avoid larger imbalances by manually activating regulating power. Manual regulating power has an activation time of 15 minutes. This means that the automatic balancing system needs to be ready to handle the system imbalance that can arise within around 15 minutes. The potential of a more gradual decrease of production from a single offshore wind farm during 15 minutes allows the integration of more wind farms into the system.
Almost all power production is balanced through well-functioning Nordic power markets (both in the day-ahead and regulating power markets). Thanks to the Norwegian hydropower system, and theconnection to Norway, a very high share of the wind power variability in western Denmark is balanced, today. With the new high wind ride through controller installed in offshore wind parks it is possible to integrate more offshore wind into the system without jeopardising system security at times of high winds.
The goal of doubling the share of wind power in fi-nal electricity consumption in Denmark (from approximately 25% to 50%) within seven years, along with increased growth in wind power capacity across Europe will significantly challenge the power system. Advanced controllers have been considered to effectively balance power variations between the Nordic Region and western Denmark so that power system balance restoration is possible in case of unforeseen large variations in (offshore) wind power generation.
Results in detail
This demonstration project concludes that it is possible to find a solution to future challenges with large amounts of offshore wind power production. At the Horns Rev II wind farm, the new high wind ride through control installed makes a big difference compared to old control algorithms. Not only does energy output increase, but the implications for the overall power system, such as instability or risk of blackouts.
More advanced control options will reduce the difficul-ties and maintain the balance in the system in high wind speed situations and keep system security at high levels as today.
The new high-wind ride through control installed at Horns Rev II wind farm increases the total wind power production. Figures 4 and 5 show the difference between power production at Horns Rev II during stormy weath er conditions on 24 September 2012 (Figure 5) and 30/31 Jan uary 2013 (Figure 6), for wind turbines with the new high wind ride through control (actual measurements). The red line shows what the turbine would have produced if the old control algorithm was still installed (simula tions), while the blue line shows what it produced with the new technology. The wind speed (grey line) is shown as the av erage wind speed over the 91 turbines.