Baumüller and Solutions 4 Energy are together developing small wind turbines with efficient generators
Fossil fuels are becoming less sustainable and that is why renewable energy is on the rise. Wind is an important alternative energy source all over the world. However, suitable locations for large wind turbines are scarce, e.g. in Germany. With its small wind turbines, the German wind turbine builder Solutions 4 Energy makes it possible to develop additional alternative locations, with an average annual yield of 100,000 kWh depending on the use. With this system, they offer an attractive solution for municipalities, agricultural operations and small and medium-sized companies.
The starting signal was given for the development of the small wind turbine 30K16 at the end of 2014. Solutions 4 Energy put the focus on three requirements: no oil in the system which ensures minimum maintenance effort, the highest possible level of efficiency and the same safety standards as with large wind turbines. The partner’s role in developing a suitable generator, which makes it possible to meet these requirements, was taken over by the Nuremberg-based drive and automatization specialist Baumüller.
Grid operation or decentralized power supply
The result is a turbine that, with an innovative concept for generator cooling and a new technology in the rotor blade area, offers a high yield, low mainenance cycles and high level of flexibility. About 25 average 4 - person housholds that each consumed about 4,000 kWh of electricity in Germany in 2017 can be supplied with the turbine's energy yield. The small wind turbine can be connected to the grid for infeed or can be used for the decentralized energy supply for self-supply. The system is available in black start-capable design, i.e. it can be used without a grid connection, which is an important aspect for use in remote areas, such as in Africa or South America. Currently, Solutions 4 Energy is working on a concept for electricity storage and other versions of island grid operation so that a permanently reliable energy supply is possible without bridging times with low wind by using diesel generator, for example.
Maximum yield with pitch technologyThe rotor diameter of the 30K16 is 16 meters, which makes it ideal for strong wind locations. The successor version 30K20 is available for weak wind locations, which can compensate for less wind with a rotor diameter of 20 meters. The small wind turbines are available in three hub heights: 22, 32 and 40 meters. It was important here that the tallest turbine also remains under 50 meters in height, making the approval process in Germany as simple as possibe. This means that the rotor blades are always put into the optimal aerodynamic position to ensure maximum yield. The pitch system is also the basis for the turbin's black start capability, since this allows for a slow system start-up without the threat of a sudden grid overload.
Everything is electric and without oil
Solutions 4 Energy places particular emphasis on a completely electrical and absolutely oil-free solution. To achieve this, the breaking must also be electric and the drive train must be realized without gearing. By having a system without without oil and gearing, the operator benefits from longer maintenance cycles and therefore lower operating costs as well as maximum efficiency. The first test system is currently in operation in Sankt Michaelisdonn near Hamburg. A duration test of 35 weeks is being carried out here to be able to test the actual availability and yield performance.
Efficient design: Generator with innovative cooling concept
The heart of the small wind turbine is the generator. The reliability and yield performance for the operator depends on this. Baumüller developed the generator DSHT-650 specifically for the small wind turbine requirements. The generator is installed directly behind the rotor blades of the wind turbine. The DSHT is a multi-pole synchronous generator. The very high level of efficiency that was tested at 91.4 percent when the small wind turbine was at full load, therefore allows for maximum energy yield. The generator has a diameter of 1300 millimeters and an overall length of 330 millimeters. Due to its multi-pole design principle, the DSHT ensures a smooth rotor blade operation, even at low speeds. This prevents vibrations from being transferred to the rotor blades due to high cogging torques. The cooling without a separate fan is a particular highlight of the generator. Solutions 4 Energy required that no electrical power be used for a separate fan, as this would reduce the system's overall yield. Baumüller solved the problem with a special generator design with cooling fins. The cooling occurs through the natural air flow that flows through the cooling fins. The cooling occurs through the natural air flow that flows through the cooling fins located transversely to the rotor blades on the outside of the generator, thus ensuring sufficient cooling. This is made possible, because the generator only produces a little temperature with its particularly high level of efficiency.
Another special feature is the generator coating. With its small wind turbine, Solutions 4 Energy meets IEC 61400-1 and thus is the only manufacturer to offer the same standards that are required for large wind turbines. The weathering resistance of the turbine must be guaranteed for twenty years to obtain this certification. Baumüller achieves the required high level of corrosion protection on the DSHT by using a special paint finish.
The innovative generator design from Baumüller and the know-how of the wind energy specialists from Solutions 4 Energy resulted in an efficient small wind turbine, which meets the most stringent requirements for safety, reliability and efficiency.