No abstract

Further improvements in the cost-effectiveness of wind turbines drives designers towards larger, lighter, more flexiblestructures in which more intelligent control systems play an important part in actively reducing the applied structural loads, avoiding the need for wind turbines to simply withstand the full force of the applied loads through the use of stronger, heavier and therefore more expensive structures. Controller research within the UPWIND project has been aimed at further developing such control strategies and ensuring that new, often larger and innovative turbines can be designed to use these techniques from the start. For this to be possible, it is important to build up full confidence in the effectiveness and the reliability of these strategies in all situations. To this end, the work reported in this paper covers several different aspects: full-scalefield testing to build confidence in the effectiveness of advanced control strategies; further development of advanced control strategies to prevent unwelcome side effects in any of the load cases that have to be considered during the design; the possibility of blades employing dual-pitch control; development of load estimation techniques that can reduce reliance on additional sensors that would otherwise be required; investigating the potential of light detection and ranging assisted feed-forward pitch control to mitigate extreme and fatigue loads; using system identification methods to improve controller tuning. The detailed results of the work presented in this paper are available in the published reports of the Control Systems work package of the UPWIND project. These reports also cover other results of the work package, which are not reported here, such as control during network faults such as voltage dips, voltage control at the point of connection to the network and gradual cut-out of wind turbines to improve output predictability in high winds. A summary report is also available

This work assesses the participation of wind power plants in primary frequency control support. To participate in frequency control-related tasks, the wind power plants have to maintain a certain level of power reserves. In this article, the wind power plant is equipped with a flywheel-based storage system to fulfil the power reserve requirements set by the network operator. The article focuses on two main aspects: the definition of the control strategy to derate the wind turbines to provide a part of the required power reserves; and the coordinated regulation of the power reserves of the wind turbines and the flywheels while participating in primary frequency control. This coordinated regulation enables the wind power plant to maintain the net level of power reserves set by the network operator while alleviating the need of deloading the wind turbines. The performance of the proposed control schemes are shown by simulation.