Vestas

About: Vestas is a company organization based out in Aarhus, Denmark. It is known for research contribution in the topics: Turbine & Wind power. The organization has 1075 authors who have published 1519 publications receiving 23285 citations. The organization is also known as: Vestas Wind Systems & Vestas Wind Systems A/S.

Variable speed wind turbines capability for temporary over-production

Abstract: New control systems for Variable Speed Wind Turbines (VSWT) need to be developed in order to provide inertia response and frequency control to support the grid. This work studies the behavior and capability of VSWT for providing temporary active power overproduction. The study is conducted on a multi-megawatt VSWT with Doubly-Fed Induction Generator. It was found that it is possible to have an active power overproduction of 0.2 pu for at least 10 seconds, which could be useful for the grid operator for restoring a critical situation of grid frequency dip. Nevertheless it is important to be aware about the underproduction power and the associated recovery period that follow a VSWT overproduction operation. The results can be used in designing suitable control systems for VSWT inertia response and frequency control.

Linear parameter varying control of wind turbines covering both partial load and full load conditions

Abstract: This paper considers the design of linear parameter varying (LPV) controllers for wind turbines in order to obtain a multivariable control law that covers the entire nominal operating trajectory. The paper first presents a controller structure for selecting a proper operating trajectory as a function of estimated wind speed. The dynamic control law is based on LPV controller synthesis with general parameter dependency by gridding the parameter space. The controller construction can, for medium- to large-scale systems, be difficult from a numerical point of view, because the involved matrix operations tend to be ill-conditioned. The paper proposes a controller construction algorithm together with various remedies for improving the numerical conditioning the algorithm. The proposed algorithm is applied to the design of a LPV controller for wind turbines, and a comparison is made with a controller designed using classical techniques to conclude that an improvement in performance is obtained for the entire operating envelope. Copyright © 2008 John Wiley & Sons, Ltd.

Control method for a wind turbine

Abstract: The invention relates to a method of controlling a wind turbine having a rotor with pitchable wind turbine blades and a generator for producing power, where a pitch reference value for the wind turbine blades is determined, and an operational parameter representing a loading on the wind turbine rotor exerted by the wind is measured at time intervals. A variation parameter reflecting a variation of the operational parameter over time is determined and used in the determination of a minimum pitch limit value of the pitch reference value. The wind turbine is then controlled according to the pitch reference value only if the pitch reference value is above or equal to the minimum pitch limit value, and otherwise according to the minimum pitch limit value. The invention further relates to a method of controlling the change in the operational parameter as measured in two successive time steps is determined and the turbine then being controlled according to a safety control strategy if the difference between the operational parameter change and the variation parameter is above a certain alert threshold. The invention further relates to a control system configured to perform the above control method, and a wind turbine comprising such system.

Wind turbine blades made of two separate sections, and method of assembly

Abstract: The invention relates to a wind turbine blade (5) comprising at least two wind turbine blade sections (12, 13) that include one or more strengthening structures (6, 6a, 6b), the ends (14, 15) of said strengthening structures being connected in a connection joint . The ends include corresponding connection surfaces, the one or more relevant dimensions of said surfaces being larger than the dimensions of the transverse surfaces of the strengthening structures at said ends. The one or more relevant dimensions of said connection joint are larger than that of the adjacent strengthening structure. The invention also relates to a wind turbine blade in which the at least two wind turbine blade sections include a number of substantially oblong carbon fiber strips and strips of one or further materials such as wood or glass fiber. The invention further relates to a wind turbine blade section, an assembly plant for assembling wind turbine blade sections (12, 13) and to a method and use of such wind turbine blades .