Pitch system design for Sewind wind park

“We were looking for a more open partner in terms of willingness to share the technology so that we could optimise the entire design in a teamwork” says Mr Xun from Sewind

In 2011, DEIF Wind power Technology was chosen as supplier of pitch systems by Chinese Sewind. Sewind is a Top 15 manufacturer measured in terms of global market share – the company is a subsidiary of Shanghai electric, Chinas largest power equipment manufacturer offering solutions for fossil power plants, nuclear power plants, renewable energy generation, power transmission, etc. Sewinds portfolio consist of 1.25, 2.0 and 3.6MW machines.

Mr Xun from Sewind says "For our high runner model – the 2.0MW machine – we were looking for an alternative to the pitch solution the turbine was originally designed with. We were looking for a more open partner in terms of willingness to share the technology so that we could optimise the entire design in a teamwork. At the same time, we were looking for a partner with a strong local presence in China. Working with complex technical applications across several time zones is not convenient" Mr Xun stresses.

"Eventhough we are a conservative company, we also wanted cutting-edge technology in our second generation pitch system. We wanted maximum yield and maximum reliability from the solution" Mr Xun continues – "That is why we chose to cooperate with SPERI (Shanghai Power Equipment Research Institute) in the screening of solutions available in the market which could fulfill our wants and needs."

"Both in terms of the technology the solution was based on and the attitude of the supplier, SPERI singled out DEIF Wind power Technology as a possible partner, and we decided to go for a full-scale test by ordering prototypes for real life testing. Initially, we were intrigued by the open attitude of DEIF" Mr Xun says. "DEIF’s openness towards sharing the technology so that together we were able to develop a solution which Sewind could continue the development and maintenance of was exactly what we was looking for."

"The first generation of our wind turbine was pretty much a ‘black box’ solution delivered to us by the supplier – we now wanted to move on, opening the ‘black box’ so we could make optimisations on our own. Exactly that attitude we found at DEIF", Mr Xun adds. "In terms of technology, we also found the solution from DEIF to be right for us.

We liked the concept simplicity from DEIF – a minimum of components equaling a maximum of reliability. The robustness of the solution is crucial to us because many of our wind turbines are deployed to remote areas. Locations we try to avoid having to send people to for unplanned service. Yet another reason why we prefer the general pitching strategy of the DEIF solution is that the continuous pitch motion keeps the idle time of the moving components at a level where no corrosion will occur. At the same time, the soft movements resulting from this strategy minimise the mechanical stress imposed on the entire construction.

We decided to make the first solution from DEIF based on traditional energy storage technology, and we have now developed it into a cutting edge solution based on ultra-cap technology", and Mr . Xun adds with a smile "that is the benefit of working with a partner mastering several technologies, it simply gives us full freedom of choice". 

"In addition, the choice becomes a safe one given the fact that DEIF can also supply all vital system components. Full freedom of choice combined with maximum supply security enables us to design technologically advanced solutions and offer them to our customers resting assured that we can actually deliver them in big numbers. Combined with the fact that DEIF has an entire R&D and service team right here in Shanghai is a unique combination we have not found elsewhere. That particular combination allows us to sleep peacefully at night", Mr.  Xun concludes with satisfaction.

Tailored Pitch System-design Case

A DEIF pitch system will always be tailored to match your turbine and your wishes.

This example is a classic solution but including advanced DEIF system components and software package to optimise system condition monitoring and including a permanent magnet motor to minimise maintenance.

Motor: The AC permanent magnet motor also known as ‘permanent Magnet Synchronous Motor’ is a well-proven component used in many industrial servo applications. It is robust and highly efficient. This motor type is the lightest technology and, at the same time, it has a high peak torque, an increasingly important feature for pitch systems due to rising wind gust impacts on the increasingly big wind turbines.

Drive: The IMD reduces the number of components in the cabinet, thus reducing the risk of connection and interface failures. All I/O’s can be controlled and all sensor feedback is transferred through the IMD for secure and operation. The IMD is a safe choice and complies with the new GL 2010 standards and the ISO 13849 functional safety.

Energy Storage: The lead acid batteries provide energy for pitching the blades to storm position when grid power is lost. The lead acid batteries are a proven technology in pitch systems, providing hassle-free performance provided that the suggested three-year replacement interval is followed. There is one common charger for the batteries. The charger is ‘intelligent’ as it has been designed for fault-tolerant operation, e .g. during LVRT (Low Voltage Ride Through) conditions. Moreover, the charger compensates for different ambient temperatures to ensure optimum charging and minimum wear of the batteries. The application comprises three chargers – one per battery bank to ensure a fully redundant system.

Control System: The pitch motion controller is a high-end configuration with a well-proven interface to the nacelle controller. The application comprises sensors, enabling optimum service and monitoring of the wind turbine. The control system further comprises monitoring of the battery lifetime and the grid connection. The pitch system is self-protected – undetected system faults cannot occur.

System design: The system can be delivered as either a 6 or 7 box solution, depending on the space inside the hub.

The system is designed for a lifetime of 20 years, if serviced annually. Some components in the pitch system have to be exchanged with a predefined interval.

Pitch control, turbine control or retrofit?