What effects does a grid failure have on a wind turbine?
Wind turbines are there to generate electricity. If there is not enough wind, the turbine stands and waits for stronger wind. But what are the consequences of a power cut, especially when the wind is blowing?
Without a power supply backup, a power grid failure would have fatal consequences for a wind turbine. The first decisive effect would be a sudden drop in load, as the generator would no longer be able to supply energy to the grid. With a modern 3.5 MW turbine, at nominal load this would mean that over 4700 hp would suddenly be unchecked. You can imagine the consequences or watch it on YouTube: To the Youtube search results*
For safe operation, it is therefore essential to be able to turn the rotor blades in fractions of a second, even after a power failure, with the help of battery-supported systems. In the rotor hub of the wind turbine, in the immediate vicinity of the electric motors that adjust the blades (the so-called pitch motors), there are battery systems that still have enough energy stored to be able to turn the blades to the safe pitch position in the shortest possible time. This slows down the rotation of the wind turbine and brings it safely to a standstill.
However, the control system must also be supplied with power from a UPS for a few minutes after a power failure in order to properly end or "shut down" all processes in the system. The message about the power failure also needs to be sent. Finally, the remote monitoring system that looks after the wind turbine needs to be informed.
Once the rotor has come to a standstill and the control system has been switched off, not everything is finished, because at night and in poor visibility, the air traffic control lights still need to be supplied with power. Today, fortunately, energy-saving red LED flashing lights and sometimes white LED flashes are used. Before LED lights were available, incandescent lamps were still required, which flashed wastefully at a whopping 4 kW. Incidentally, there always have to be two lights because one light could be covered by a blade of the wind turbine and would therefore not be visible to the approaching aircraft.
But there is still a task for the emergency power supply: the interior tower lighting. In the event of a power failure, any service personnel on the installation cannot use the convenient electric elevator that is commonly used today to descend, but have to use a ladder to get back down to earth. For this descent inside the tower, they need emergency lighting for the descent time in order to make their way back safely. This is also provided by an emergency power system.
Robust and highly reliable uninterruptible power supplies (UPS) from Wöhrle SVS are used in many wind turbines to meet the demanding requirements of such systems.