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Pitch drive controllers play a central safety role in wind turbines

28 January 2021

KEB AUTOMATION is seeing an increase in demand for its drive controllers, motors and brakes for onshore and offshore wind turbines. Pitch and yaw drives, pitch motors, as well as pitch and yaw brakes from KEB, are proving popular as a central safety component in wind turbines, including the latest high power (10MW and above) turbines.

"The trend is clearly towards ever larger, more powerful wind turbines," says Sebastian Eicke, applications engineer in the wind energy team at KEB Automation. "This is closely linked to the repowering of existing plants and the expansion of offshore wind farms."

The manufacturers of wind turbines have special requirements that must be met. "In the wind sector, robustness plays an important role, as do long maintenance intervals, because the turbines are exposed to a wide variety of environmental conditions," explains Roger Brohl, product manager for the wind sector at KEB Automation. "From very cold to very warm, with high vibrations in the nacelle, which means drives and brakes have to withstand everything."

Brohl continues: "The keyword here is safety. The pitch drives are a central safety component of the wind turbine. In the event of a power failure, a storm or a fault, they must ensure that the turbine blades reach a safe position – the so-called vane position."

"In the Chinese market, we can probably call ourselves, without false modesty, one of the market leaders in pitch inverters," says Eicke. "For example, the new COMBIVERT 23P6 pitch inverter from KEB is particularly well suited to large wind turbines of around 10MW and above. The pitch drives are also joined by yaw drives for aligning the turbine in the direction of the wind – so-called wind tracking. The system can be completed with the use of KEB brakes and motors. The COMBISTOP range of spring-applied brakes, for example, are specially optimised for use in wind turbines, enabling universal installation on synchronous or asynchronous motors, for onshore, nearshore or offshore wind turbines."

The KEB product portfolio for wind turbines includes pitch drives, pitch motors, pitch and yaw brakes, yaw drives, and software for remote maintenance and control of these products.

Pitch drive controllers

Specially developed for use in electrical pitch systems, the COMBIVERT P6 meets all the requirements for rotary use in the hub of wind power facilities with the prevailing local vibration and temperature loads. In active operation, the electrical system output and speed of the hub are controlled by the rotor blade position. In case of failure of the turbine itself or in the supply network, the pitch inverter fulfils the task of protecting the wind power facility against dangerous overspeeds or brings it to a halt by fast turning of the rotor blades away from the wind.

COMBIVERT P6 is an active part of the wind turbine safety system and is certified by TÜV Rhineland. In safety operation of the entire pitch system, consisting of three COMBIVERT P6 drives, the solution achieves Performance Level "d" according to EN ISO 13849-1. The COMBIVERT P6 therefore meets the requirements of GL Guidelines for the certification of wind power facilities (2010) – a key basic requirement for the European market.

A unique feature of the COMBIVERT P6 is the high level of integration of the inverter, the loading device for the energy storage system and a PLC, all in an extremely compact format. The P6 provides CAN, PROFIBUS and realtime Ethernet connectivity, therefore offering flexibility and making it easily adapted to a wide range of customer requirements.

Pitch motors

Modern wind turbines and all their integral sub-assemblies are designed for a service life of at least 20 years. Wind turbines installed onshore, nearshore or offshore must withstand harsh environmental conditions which requires systems and solutions that deviate from industry-standard ones.

The KEB Pitch Motor is specially designed to withstand these harsh environmental conditions and is based on the knowledge and experience gained from more than 10 years’ practical application 10,000-plus installations. The KEB Pitch Motor is a synchronous servomotor with integral spring pressure. The Pitch Motor stands out due to its high efficiency, compactness and low weight. The motor is easily adapted to existing gearboxes by using different flange configurations. KEB Pitch Motors also meet the very highest requirements in terms of quality, dynamics and positioning accuracy.

Pitch & yaw brakes

COMBISTOP spring-applied brakes from KEB are specially designed for use in wind turbines, enabling universal installation (onshore, nearshore and offshore) as add-ons for synchronous and asynchronous motors. The brakes are protected from corrosion, high vibration and impact and are configured for 100% power-on-time. The brakes are easy to install and are failsafe through the use of special continuous stroke-safe springs.

Yaw drive controllers

Wind turbines with increasingly large rotors and tower heights are being built in the landscape. As the size and capacity increase, so do the requirements for drive controllers used to regulate and control them – in both the hub and the nacelle. Yaw drive controllers handle ‘yawing’ and are a key component for maximising turbine availability. In the offshore sector, minimising maintenance with maximum failsafe performance are key criteria. KEB offers variants from industrial use for azimuth applications using COMBIVERT drive controllers. Their extensive range of functions provide an excellent basis for flexible adaption to different wind turbine manufacturer’s designs.  Depending on the preferred design arrangement, drive controllers are available as single-axis units or as multiple-axis systems in the range of 4 to 75kW.

Remote maintenance

With access to the technical parameters of a wind turbine installation, it is possible to evaluate any fault situations that may occur and eliminate these as required, establish preventive measures and also take action directly in the functional processes and procedures.
COMBIVIS Connect software from KEB offers a VPN-based connection platform that provides reliable, secure access from anywhere in the world. The properties and possibilities of remote maintenance are directly integrated in many KEB control products. If third-party control systems are used in the wind power facility, the COMBICONTROL C6 router from KEB offers a universal solution for incorporating these components. Software drivers are currently available for more than 50 different manufacturers. The C6 router can also be equipped with the COMBIVIS HMI visualisation system.