FIELD

This invention relates generally to wind turbine generators, and more particularly, to a system for cooling the windings of a rotating generator component.

BACKGROUND

Wind turbines have received increased attention as an environmentally safe and relatively inexpensive alternative energy source. With this growing interest, considerable efforts have been made to develop wind turbines that are reliable and efficient.

Generally, a wind turbine includes a plurality of blades coupled via the rotor hub to the main shaft of the turbine. The rotor hub is positioned on top of a tubular tower or base. Utility grade wind turbines (i.e., wind turbines designed to provide electrical power to a utility grid) can have large rotors (e.g., 100 or more meters in diameter). The rotor blades transform wind energy into a rotational torque or force that drives the generator, rotationally coupled to the rotor.

Superconducting generators are being explored for use in wind turbine installations, particularly in offshore installations. These generators use superconducting field windings and assemblies of armature coils, cooling systems, and nonmagnetic teeth disposed between bars in the armature. In a particular design, the superconducting generator includes an armature assembly that, unlike conventional generator configurations, rotates within a superconducting field assembly, which includes a cryostat with superconducting field coils inside the cryostat.

There is a recognized need in the industry to provide reliable and effective cooling to the rotating armature assembly. For example, U.S. Pat. No. 7,928,616 describes a superconducting generator having a field assembly that includes a superconducting field winding configured to produce an electromagnetic field coupled to an armature assembly, wherein the armature assembly rotates relative to the stationary field assembly. The armature assembly is a laminated construction and includes a magnetic body portion and magnetic teeth portions extending from the magnetic body portion. A slot is defined by the magnetic body portion and adjacent teeth portions, and an armature bar engages in the slot. A cooling cavity is partially defined by the tooth portion and communicates with the front surface and the rear surface of the tooth portion to cool the armature bar, wherein the cooling cavity is operative to receive air or a liquid coolant to cool the armature assembly. Tube members may engage in the cooling cavity operative to carry the liquid coolant.

Liquid cooling of the rotating armature assembly is far more effective and efficient than air cooling. However, the ability to cool a large rotating component such as an armature assembly in a superconducting generator generally requires the use of seals between the stationary cooling equipment and the rotating armature assembly. Such seals are complex, generally unreliable and prone to leakage/failure, and significantly increase the service and maintenance costs of the generator.

Accordingly, the industry would benefit from a liquid cooling system for a rotating component of a generator that is reliable, cost effective, and does not rely on seals between rotating and stationary components thereof.

BRIEF DESCRIPTION

Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention

In one aspect, the present disclosure is directed to a generator that, although not limited to such use, is particularly well-suited for use in a wind turbine installation (either and offshore or an onshore wind turbine installation). The generator includes a first stationary component carrying a first electromagnetic component configuration (such as a winding or magnet configuration), and a second rotating component carrying a second electromagnetic component configuration (such as a winding or magnet configuration), wherein the second rotating component is arranged to rotate around the first stationary component. It will be appreciated that the rotating component may also be disposed within the stationary component without limiting the disclosure herein. The second rotating component may be configured with a field winding configuration or an armature winding configuration and includes a body portion and a plurality of teeth spaced around and extending radially from the body portion, the body portion and the teeth extending longitudinally between opposite end faces. A slot is defined between adjacent teeth, wherein the second electromagnetic component configuration arranged in the slots (e.g. in the form of coils or bars). A housing is arranged around and rotatable with the body portion. A heat exchange circuit is arranged on the second rotating component and includes one or more coolant channels defined longitudinally in the teeth between the opposite end faces of the teeth. One or more pumps is carried by the second rotating component, for example arranged beneath the housing outboard of the stationary component so as to rotate with the housing. A heat exchanger is arranged on the housing so as to be rotatable with the housing, the heat exchanger arranged across the housing transverse to a rotational direction of the housing such that rotation of the housing forces air flow through the heat exchanger. The heat exchanger position may be angled so as to optimize the amount of air flow through the heat exchanger. A liquid coolant is provided and the heat exchanger, the pump, and the coolant channels are in a closed-loop configuration such that the liquid coolant is pumped through the heat exchanger and the coolant channels to cool the second winding configuration.

In a particular embodiment, the generator is a superconducting generator and the first stationary component includes a superconducting field winding configuration and the second rotating component includes an armature assembly with the second electromagnetic component configuration having coils or bars arranged in the slots.

In a certain embodiment, the heat exchanger is pivotably arranged on the housing and is pivotal between a functional position extending radially outward from the housing and a stowed position folded down against the housing.

The heat exchange circuit can have various configurations. For example, the circuit may include an inlet manifold and an outlet manifold that are in fluid communication with the coolant channels defined in the teeth. The liquid coolant is pumped from the inlet manifold, through the coolant channels, and into the outlet manifold. The inlet manifold and the outlet manifold may each be arranged at one of the opposite end faces of the body. Alternatively, the inlet manifold and the outlet manifold are arranged at a common one of the end faces of the body such that the coolant flow reverses at the opposite end face to return to the outlet manifold (e.g., the coolant makes at least two passes in each tooth).

The heat exchange circuit may include thermally conductive tubes (e.g., stainless steel tubes) disposed through the coolant channels to conduct the liquid coolant therethrough, the tubes connected to the inlet manifold and the outlet manifold. With this embodiment, the inlet manifold and the outlet manifold may be arranged at a common one of the end faces of the body, with the tubes disposed in a first one of the coolant channels in the teeth, reversing direction at the opposite end face of the body, and running through a second one of the coolant channels in the same tooth.

The heat exchange circuit may include a plurality of the pumps and a plurality of the heat exchangers, each of the heat exchangers pivotably arranged on the housing and pivotal between a functional position extending radially outward from the housing and a stowed position folded down against the housing. The face of the heat exchangers may face only in the tangential direction, or simultaneously in the tangential and axial directions.

The pumps and heat exchangers can be variously configured in the heat exchange circuit. For example, the heat exchange circuit may have all of the heat exchangers and the pumps in a parallel configuration with all of the coolant channels. In this arrangement, a single one of the pumps and one of the heat exchangers can service all of the coolant channels if need be.

In an alternate embodiment, the heat exchange circuit is divided into a plurality of sub-circuits, with each of the sub-circuits configured in a closed-loop with a subset of the coolant channels and having at least one of the heat exchangers and at least one of the pumps. Each sub-circuit may include an inlet manifold configured at one of the end faces of the body and an outlet manifold configured at the opposite end face of the body, wherein the liquid coolant is pumped from the inlet manifold, through the coolant channels assigned to the sub-circuit, and into the outlet manifold.

The present invention also encompasses a wind turbine (onshore or offshore installation) that utilizes a superconducting generator to generate and supply electricity to a grid. The superconducting generator includes a stationary field assembly with a superconducting field winding configuration and a rotating armature assembly that rotates around the field assembly and includes a body portion and a plurality of teeth spaced around and extending radially from the body portion, the body portion and the teeth extending longitudinally between opposite end faces and defining slots between the teeth. An armature winding configuration in the form of coils or bars are arranged in the slots. A housing is arranged around and rotatable with the body portion. A heat exchange circuit is arranged on the rotating armature assembly and includes a pump and at least one coolant channel defined longitudinally in each of the teeth between the opposite end faces of the teeth. A heat exchanger is arranged on the housing and is rotatable with the housing, the heat exchanger arranged across the housing partially or completely perpendicular to a rotational direction of the housing such that rotation of the armature assembly forces air flow through the heat exchanger. A liquid coolant is provided, wherein the heat exchanger, the pump, and the coolant channels are in a closed-loop configuration such that the liquid coolant is pumped through the heat exchanger and the coolant channels to cool the armature winding.

Various embodiments of the wind turbine may include any of the embodiments of the generator discussed above.

