Future Hydraulic Pitch Systems

Project Details


The pitch system of a wind turbine is one of the systems utilized for regulating the power production of the wind turbine. The Pitch system may turn the blades of the turbine from approximately 0 to 90 degrees around its own axis and thus regulate the energy input from the wind to the turbine. If the blades are turned into a 90 degrees position the turbine will stop rotating and the energy production is stopped. If an error occurs in the turbine and it is necessary to shut the turbine down before extensive damage occurs an emergency stop is performed by turning he blades to their 90 degrees position. The pitch system is the primary safety system of the turbine.
As the pitch system has an essential function of the wind turbine it is extremely important that the system is reliable and available. Especially for offshore wind turbines it is extremely important that no other maintenance than the scheduled has to be performed. Research shows that pitch systems currently are responsible for 22% of wind turbines total downtime.
A combination of lower cost and increased reliability and availability on the hydraulic pitch system will reduce both the total cost of ownership (TCO) and Total Cost of Energy (TCE).
This project aims to significantly increase reliability and availability of the pitch systems compared to current hydraulic and electric pitch systems. This is done through a modular way of thinking in which the entire system is brought out in the rotating hub and distributed in three individual systems - one for each wing. Through this transformation it is the goal to reduce the price by 20% while the number of components is lowered by 10%.
To increase uptime for a hydraulic pitch system, external leakage from the hydraulic components must be eliminated. This will be achieved through reductions in external leakage paths to both the environment in the hub of the turbine and nature where the turbine is erected. In 2012, 74% of the offshore wind turbines were installed with hydraulic pitch systems. Of the total offshore
capacity 86% of the turbines are controlled by hydraulic pitch systems (2012). It is the goal for the new hydraulic pitch system that it must be in new offshore wind turbines already being installed with hydraulic pitch, but by the modular thinking and plug and play setup is it possible to access turbine manufacturers who use electric pitch and thus take greater market share.
Effective start/end date01/01/201430/06/2017


  • EUDP: DKK10,425,277.00

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  • Prizes

    University Prize Esbjerg 2018

    Liniger, Jesper (Recipient), 22 Nov 2018

    Prize: Research, education and innovation prizes

    Research Output

    • 4 Article in proceeding
    • 3 Journal article

    Early Detection of Coil Failure in Solenoid Valves

    Liniger, J., Stubkier, S., N. Soltani, M. & Pedersen, H. C., Apr 2020, In : IEEE - ASME Transactions on Mechatronics. 25, 2, p. 683-693 11 p., 8974206.

    Research output: Contribution to journalJournal articleResearchpeer-review

  • Feasibility Study of a Simulation Driven Approach for Estimating Reliability of Wind Turbine Fluid Power Pitch Systems

    Liniger, J., N. Soltani, M., Pedersen, H. C. & Sepehri, N., Jun 2018, Safety and Reliability – Safe Societies in a Changing World: Proceedings of the 28th International European Safety and Reliability Conference (ESREL 2018), Trondheim, Norway, 17–21 June 2018. Haugen, S., Barros, A., van Gulijk, C., Kongsvik, T. & Vinnem, J. E. (eds.). 1 ed. CRC Press/Balkema, p. 2037-2044 8 p.

    Research output: Contribution to book/anthology/report/conference proceedingArticle in proceedingResearchpeer-review

    Open Access
  • 1 Citation (Scopus)
    156 Downloads (Pure)

    Model-based Estimation of Gas Leakage for Fluid Power Accumulators in Wind Turbines

    Liniger, J., Pedersen, H. C. & N. Soltani, M., Oct 2017, Proceedings of ASME/BATH 2017 Symposium on Fluid Power and Motion Control. American Society of Mechanical Engineers, 10 p. FPMC2017-4253

    Research output: Contribution to book/anthology/report/conference proceedingArticle in proceedingResearchpeer-review

    1 Citation (Scopus)