Wind ramps, which gave the project its name, are strong changes in wind speed within periods of less than half an hour. Such strong changes complicate the integration of wind turbines, and offshore wind turbines in particular, into the electricity grid, as the power fed into the grid fluctuates with the wind speed. If these power fluctuations occur unexpectedly, compensation can be difficult and correspondingly expensive. In the case of large-scale wind phenomena, several wind farms can be affected at the same time, which makes the situation even more critical. This puts a heavy strain on the grids and increases the price of electricity from wind power. In the course of the decarbonisation of the energy market, a better forecast of the wind is therefore crucial in order to be able to react at an early stage on the power exchange. For times longer than a few hours there are established methods that are used productively to regulate the wind energy market.
In the critical area of wind ramps, there is no such method. To solve this problem, the Windramp project is investigating the entire chain from the measurement of the wind field to the traders at the electricity markets. Strong winds can reach speeds of over 60 km/h, so that for a forecast over half an hour, one has to measure over 30 km in the direction of the wind. The method of choice for making these measurements is Doppler lidar. However, there are no commercially available devices that can reliably achieve this range. Devices with nearly sufficient power are too large to be installed on offshore wind farms. To solve this problem, Abacus Laser GmbH is developing a new type of Doppler lidar instrument using state-of-the-art laser technology with the goal to create
Technical advances in the fields of pumplasers, optics and detector technologie allow for new gain materials in the 2 μm wavelength region to be used. Furthermore, as narrow linewidth and robust reference lasers in this wavelength region – which are crucial for a lidar instrument – are not commercially available or extremely expensive, a new reference laser is beeing developed.
At the same time, another device is being tested which, thanks to a new modulation technique, enables a higher spatial resolution than conventional Doppler lidar instruments and, with a range of approx. 20 km, will set standards in data availability. The device will hardly be larger than the previous LiTra S.
An offshore-capable housing with a build-in scanner is developed by our partner METEK Meteorologische Messtechnik GmbH.
The starting point for the development is the limitation of the laser power of the Doppler (https://en.wikipedia.org/wiki/Atmospheric_lidar#Wind) lidar instrument by eye safety. Higher power corresponds to a higher range. At the same power, however, the range is higher if pulses with a lower pulse repetition frequency and higher pulse energy are used. Abacus Laser takes advantage of this and uses novel solid-state laser concepts to build devices with exceptionally high pulse energies of several tens of millijoules.
By utilising a modern MOPA (Master Oscillator Power Amplifier) concept based on Ho:YAG, a laser with an exceptionally low count of optical components was build. A compact laser oscillator generates pulses of 500 ns duration and 0.5 mJ of energy. An amplifier which amplifies these pulses to 30 mJ is beeing tested.
For the new reference laser a new, passive stabilisation technologie was developed. It achieves properties similar to a NPRO laser in a simple linear cavity.
For the device with a new modulation technique, a hybrid concept of fibre and crystal amplifier in the 1.5 μm wavelength band is constructed. New gain materials are combined with proven technologie from the LiTra S
Project sponsor and other partners
Press releases (in German)