Application of power devices in wind power generationWind power equipment using electric and electronic technology is being gradually adopted around the world, especially in some Asian countries and the United States, where offshore wind power is playing an increasingly important role. However, if the generation system does not have appropriate matching components, it will not improve the generation efficiency. SKiiP ® intelligent power module is optimized for the wind turbine. For components and applications: greater current, parallel operation, and more efficient cooling.
About 80 per cent of installed wind turbines with electronic control systems use inverters to control rotor currents. The main advantage of this kind of motor is that it is only designed to be 20% of the rated output power of the wind power unit, because 80% of the power is generated in the stator winding and the stator is directly connected to the power grid. The only drawback, however, is the high cost of slip-ring contact and indirect control (system) maintenance. When the power grid is disturbed, a very large rotor current is needed to keep the power grid stable in a bad environment.
Renewable energy is a supplement to conventional energy and is in fact trying to replace it, largely because of technological advances. Especially in countries where energy demand is high, 35km2 wind farms have emerged in recent years. In order to ensure the stability of the power grid, the requirements for the stability of reactive power supply and power grid become more and more strict when the power grid voltage drops sharply. For this reason, when installing a new wind turbine, with full power converters are increasingly using synchronous or asynchronous generator, because they can support grid in power grid power failure. The converter is directly controllable and provides the best frequency synchronization with 50 or 60Hz power grid, which can not only compensate the harmonic reactive power, but also generate reactive power compensation. In addition, synchronous generators can be equipped with many poles (>50) to make the drive part of the gear appear redundant. In the past, these gears were the most common cause of failure.
In the inverters used in various power systems, the inverters with rated voltage of 690V are often used for economic reasons and for the best efficiency. A power converter consisting of an IGBT with a blocking voltage of 1700V is normally used for power adjustment with a 20kV power grid. The more expensive 3.3kv modules are rarely used because the system requires transformers, making the entire solution too expensive.
More power and more power electronic devices
The power range of wind turbines is designed to be larger and larger, although location is the most important factor in output power. Of the onshore wind turbines,3MW has proved the most economical, while offshore wind farms with output of 5MW or more are a better solution. If there are two types of wind turbine - doubly-fed induction motor and synchronous/asynchronous generator with a full power converter can provide the same output, full power converter power must be five times higher. And that means five times as much power electronics. However, it must be taken into account that the output frequency of the doubly-fed asynchronous motor is low, and it usually only needs to be increased to 3-3.5 times.
However, power electronics are not only becoming more and more popular. In fact, the requirements they meet are changing. Because of the different heat of the semiconductor at low temperature in the doubly-fed asynchronous motor, protection mechanism must be adopted to deal with it. The components must meet changing requirements because of extreme weather conditions. For example, offshore wind turbines are affected by high humidity, while wind turbines in Texas are exposed to high temperatures. Therefore, the cooling system used must adopt different design. Therefore, it is important to develop cooling solutions for various applications based on rich experience.