DE102013213479A1 - Underwater power plant - Google Patents

Abstract

Underwater power plant with a generator having a stator and a rotor, wherein in the gap between the stator and rotor water is, and the encapsulated stator is flowed around by water, wherein the generator is a reluctance machine.

Description

The invention relates to an underwater power plant, in particular a tidal or a river power plant.

Underwater power plants are known from the general state of the art. In doing so, e.g. freestanding underwater power plants immersed in a sea current or a river current. These are usually power plants, which have a propeller-shaped rotor and a nacelle, wherein the nacelle accommodates the generator. However, they can also be so-called hydrokinetic turbines, which have venturi-type tubes before and / or after the turbine for accelerating the water flow driving the turbine.

Underwater power plants submerged in a current must fulfill special requirements with respect to the lifetime and the reliability of the operation, since the accessibility to underwater power plants is technically very difficult and therefore very expensive. Malfunctions that can possibly lead to maintenance work must therefore be reduced to a minimum. A design that is as simple and fault-tolerant as possible meets this requirement very well.

For example, describes the DE 10 2008 031 615 A1 an underwater power plant, which has an electric generator with a rotor with permanent magnetized rotor poles. By the use of permanent magnetized rotor poles can be dispensed with an electrical excitation, whereby the associated possible source of error is avoided constructively. In a particularly preferred embodiment, the electric generator is formed flushed with water. In particular, the air gap between the generator rotor (rotor) and the generator stator is flooded. The advantage of the water-pervaded embodiment is, on the one hand, the fact that the omission of an encapsulation and sealing of the entire generator avoids the possible malfunction which can be caused by a failure of the seal. In addition, the generator is cooled directly by the water around it, thereby saving a separate cooling system, which in turn is itself a potential source of error.

The described advantages of the cited prior art are paid for by the fact that the use of permanently excited rotor poles requires a special and complicated assembly method (see section [0005]). In addition, permanent-magnet rotor poles are very heavy and require a special complex suspension of the poles on the generator rotor core. In addition, appropriate protective measures must be taken to protect against demagnetization, corrosion or excessive temperature of the magnets. Furthermore, the permanent magnetization of the rotor poles interferes with the handling and the entire installation process.

The inventor has set itself the task, while maintaining the advantages resulting from the cited prior art, to remedy the disadvantages mentioned and in addition to reduce the cost of construction and maintenance of the underwater power plant.

According to the invention this object is achieved by a generator with the characterizing features of claim 1. Further advantageous embodiments of the device according to the invention will become apparent from the dependent therefrom dependent claims.

The inventor has realized that this object can be achieved by using a reluctance machine as a generator. Reluctance machines require neither electrical excitation nor permanent magnetic poles. Reluctance machines are simple and result in low manufacturing costs and a longer life.

If the reluctance machine is designed as a synchronous reluctance generator, there are no appreciable differences with respect to the permanent-magnet synchronous machine with regard to the integration of the reluctance machine into the power plant concept. The disadvantage that results from the slightly lower efficiency compared to a permanent-magnet synchronous machine is more than offset by the advantages described in an underwater power plant. By avoiding error-related long and expensive maintenance work and the lower investment costs, the overall benefit for the operator is increased.

The embodiment of the reluctance machine as a switched reluctance generator is particularly advantageous when the underwater power plant has to run at variable speeds. This results even in a higher efficiency whose values are over a wide working range of over 85% and are larger than in the induction machine ( Joanna Bekiesch: "Sensorless operation of a switched reluctance machine", Dissertation of the University of Siegen ).

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102008031615 A1 [0004]

Cited non-patent literature

• Joanna Bekiesch: "Sensorless operation of a switched reluctance machine", dissertation by the University of Siegen [0010]

Claims (3)

Underwater power plant with a generator having a stator and a rotor, wherein in the gap between the stator and rotor water is, and the encapsulated stator flows around water is characterized in that it is the generator is a reluctance machine. Underwater power plant according to claim 1, characterized in that the reluctance machine is a synchronous reluctance generator. Underwater power plant according to claim 1, characterized in that the reluctance machine is a switched reluctance generator.