Fluid reaction surfaces (i.e. – impellers) – Method of operation
Reexamination Certificate
2002-08-20
2004-08-31
Look, Edward K. (Department: 3745)
Fluid reaction surfaces (i.e., impellers)
Method of operation
C416S031000, C416S155000
Reexamination Certificate
active
06783326
ABSTRACT:
The invention relates to a means for adjusting a rotor blade, the long axis of which extends out from the hub of a wind power plant rotor, about an azimuthal adjusting angle in relation to the long axis, and to a process for operating this means.
Controlling or regulating the azimuthal angle setting of the rotor blades of wind power plant rotors makes it possible to reduce the angle of incidence at high wind speeds. Thus the rotor speed and the power from the generator driven by the rotor can be limited, preventing overloading of the mechanical and electrical components of the wind power plant. Corresponding systems operated electrically or hydraulically have been known for many years. Those include systems with adjusting drives in the rotor hub or in a [LP] tubular section with a nonrotating connection to the rotor blade. Systems which are integrated directly into the rotor blade are also known (DE-A 196 34 059).
There are also partially redundant systems in which, for example, a collective hydraulic central adjusting means is combined with three individual hydraulic adjusting means installed in the rotor hub which individually cover only part of the adjustment range required at low-load operation. There are also occasional designs of fully redundant drive systems for rotor blade adjustment. Those, however, have no redundancy for the case of blocking of the rotating connection between the rotor blade and the rotor hub.
For example, if one of the rotor blades fails during a disconnection from the network or an emergency shutdown of the adjusting system, that rotor blade remains in its operating position, while the other rotor blades are adjusted into their braking positions. The resulting aerodynamic imbalance, especially for large rotors 100 m or more in size, leads to such high stresses that they represent the case of extreme load which must be taken into consideration in designing many major components of the turbine.
The invention is based on the objective of providing a means of the sort initially stated which assures reliability by complete redundancy while still allowing design savings on the entire wind power plant to make up for the added cost needed.
This objective is attained according to the invention by a means comprising two independent adjusting systems, each of which adjusts the rotor blade even if each of the other adjusting systems fails.
In the means according to the invention, the azimuthal adjusting movement of the rotor blade is made up of the adjusting movements of both the adjusting systems. As the two are independent of each other, if one of the two adjusting systems fails, the other one will still do the adjusting. The cost of this complete redundancy is more than compensated by a distinct reduction of the extreme loads which must be considered in dimensioning.
It is understood that one means according to the invention is provided for each rotor blade of the rotor. For examples, rotors with two or three rotor blades have, correspondingly, two or three means according to the invention. The drive energy for the adjusting system can be hydraulic, electrical, or mechanical in a known manner. The mechanical energy can, for example, utilize the rotational energy of the rotor. Energy storage can be provided independently for each means. Alternatively, a single energy store can be utilized jointly for all the rotor blades of a rotor. In any case, the drive energy can also be obtained from internal or external forces operating on each rotor blade, such as air, mass, inertial or centrifugal forces.
One suitable embodiment of the means has each of the two adjusting systems placed between the rotor hub and the rotor blade, with a rotatable coupling which can be adjusted by the drive. That can, for instance, be accomplished by adding the additional adjusting system to the adjusting system normally placed at the rotor hub. Alternatively, though, both adjusting systems can be placed outside the rotor hub, at a distance from it, along the longitudinal axis of the rotor blade. All the common [see Translator's note 1] drive systems, such as electrical drives, hydraulic cylinders, screw spindles, and the like, are covered by the drive concept in this description and the claims.
It may be advantageous to place the two rotatable connections so that they are essentially concentric with each other. In this case, they have the same radial position with respect to the rotor axis. Then the flanges of the rotor blade and the rotor hub which connect to the rotatable connections can be made with clearly different diameters. Under certain conditions, such as limitations due to transport logistics, that can make an advantageous contribution to the economic optimization of the wind power plant.
With respect to a simple modular design, it is advantageous to place the two rotatable connections separated axially from each other along the long axis of the rotor blade, and particularly to place one of the two rotatable connections and its drive at the rotor hub and the other rotatable connection and its drive outside the rotor hub. In this case, the adjusting system at the rotor hub and the other, as a separate unit, are axially separated from each connecting flange of the rotor hub.
The structure is particularly simple if the rotatable connection outside the rotor hub and its drive are placed on a tubular part extending axially between the two rotatable connections. Then the tubular part can also be used to hold the drive energy store for the adjusting system. At the same time, the tubular part can be used to adapt the rotor diameter to different sites with the same rotor blade. The tubular parts of different lengths (extenders) needed for that can preferably be made of fibrous composite materials such as glass fiber reinforced or carbon fiber reinforced plastic. A winding process is preferably suited for that.
Another suitable embodiment has one of the two rotatable connections and its drive at the rotor hub and the other rotatable connection and its drive connected directly to the rotor blade. That is particularly suitable for high-wind sites at which a small rotor diameter is advantageous. The intermediate segment (extender) formed by the tubular part is omitted in this case. The drive for the rotatable connection on the rotor blade and other components connected with it can be placed either inside or outside the rotor blade.
It is specifically provided, as part of the invention, that the two adjusting systems can be actuated simultaneously. In that way, the adjusting speeds needed in a safety shutdown can be achieved with a particularly economical design of the means because the adjustment speeds are the sums of those for the individual adjusting systems. For example, consider a wind power plant having a three-blade rotor and in which the necessary adjusting speed is to be 7°/second. Thus this wind power plant has three adjusting means, each with two independent adjusting systems, for a total of six adjusting systems. As an example, three of them can be operated at a maximum adjusting rate of 3°/second with the other three at 4°/second. If the wind power plant is robustly dimensioned, it is adequate to equip the three adjusting systems with the lower adjustment rate with just one common drive and/or energy storage system (collective adjusting system), while the adjusting systems with the higher rates are designed completely independent of each other. In all, then, there are four completely independent adjusting systems. If a single adjusting system fails, then two rotor blades are driven at 7°/second and one at 3°/second. But if the collective system fails, then all three rotor blades are driven at 4°/second. Both types of failure produce substantially lower loads than is the case for the state of the technology, where blocking of one rotatable connection results in two rotor blades being adjusted at 7°/second while the third rotor blade does not move at all. For highly optimized wind power plants, however, it will be reasonable to make all the adjusting sy
Anemüller Jochen
Lütze Henning
Riesberg André
Weitkamp Roland
Blakely , Sokoloff, Taylor & Zafman LLP
General Electric Company
Look Edward K.
McCoy Kimya N.
LandOfFree
Means for adjusting the rotor blade of a wind power plant rotor does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Means for adjusting the rotor blade of a wind power plant rotor, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Means for adjusting the rotor blade of a wind power plant rotor will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3337224