In the forests of Canada, in remote Australian villages or on the North Sea: Wind turbines are expected to provide a reliable electricity supply for over twenty years. To this end, the internal electronics of these gigantic structures must be protected from cold, overheating and dust, while also being able to operate reliably.
The climate places extreme demands on wind turbines
In 2018, nearly 31,000 wind generators were installed in Germany alone, according to Germany’s Wind Energy Association. China and the United States top the list of countries recording the largest growth in wind energy worldwide.
Each system must be adapted to the climatic conditions, depending on the location. At Canada’s Lac Alfred, the temperature often falls below -30 °C in winter. Heating systems stop ice forming on the rotor blades and causing imbalances. The electronic components also have to be protected from the cold. That is why a heater is installed inside the enclosures to keep the temperature at around five degrees above freezing. On the other hand, heat is the main challenge at Mount Mercer in the Australian state of Victoria. At times, currents of several thousand amperes can flow through the power electronics inside the enclosures. Even at the very highest levels of efficiency, a great deal of waste heat still needs to be reliably and efficiently dissipated from the enclosures at summer temperatures, using Rittal fan-and-filter units. In regions where agriculture is of major importance, the enclosures must also protect the electronics particularly well from dust.
Quality control is essential
Every single component in the wind turbine must function optimally. In typical installations, ten to fifteen enclosures are used in each wind turbine. One of the most important enclosures is the so-called “top box” at the top of the nacelle. From here, the drivetrain, among other things, is monitored and the rotation of the nacelle is regulated. This makes it all the more important to provide shock-protection. For this reason, Rittal has developed a variant of the VX25 enclosure in which the mounting plate is mechanically reinforced. The “bottom box”, the counterpart to the top box in the nacelle, is installed inside the tower and also assumes control and monitoring functions. In most installations, this is also where the inverter is located; it is installed inside four to six bayed enclosures. It gives the wind-generated current the correct frequency for infeed into the grid. For this purpose, it has proven particularly convenient that the VX25 enclosures from Rittal can also be extended very flexibly like in a modular system and then arranged in rows (bayed) in all directions. The enclosures are also extremely robust, in terms of resistance to corrosion and damage, for example
Developing towards Industry 4.0
In some installations, the wind turbines already send their most important operating data regularly to the wind turbine operator’s central database: This information is important in assessing how well the systems are working at any given moment. The objective is that wear parts can be replaced precisely when needed. This also applies, for example, to the fan-and-filter units on the enclosures. The more accurately the time is selected, the more efficiently the maintenance costs can be reduced.
One solution offered by Rittal is the use of fan-and-filter units employing EC technology. Besides consuming less power, they also allow the fan to be controlled via the standard, integrated control interface and they permit the monitoring fan speed and function. In addition, the speed of the Rittal fan-and-filter units can also be regulated. This increases the fans’ energy efficiency and service life.
Rittal is also the right partner when it comes to cooling the enclosures: The active cooling units from the Blue e+ range can even be assigned their own IP addresses. This way, the measured values from all the sensors are displayed in the cooling unit. The RiDiag software application can be used to communicate with the cooling units via either USB or a network. With this diagnostic software, cooling devices now become an integral part of Industry 4.0 concepts. The diagnostic software optimises operation, which in turn leads to further major savings.