CA2479517A1

CA2479517A1 - Libra tower for wind turbine

Info

Publication number: CA2479517A1
Application number: CA002479517A
Authority: CA
Inventors: Alfred L. Mathieu
Original assignee: Individual
Current assignee: Individual
Priority date: 2004-09-15
Filing date: 2004-09-15
Publication date: 2006-03-15

Abstract

The purpose of the invention is to create a tower termed the Libra Tower that has a primary function of being sufficiently high for modern wind turbine generators, is of relatively simple construction, is non-rigid in structure, and has the wind turbine on top of the vertical tower operating in a horizontal and rotatable position.

The secondary function of they Libra Tower is to have the ability of limited rotation and thus easily lowering the tower with the turbine to ground level, more or less, for critical repairs, without the use of an industrial crane. Thus the "down time" which can be a crucial economic factor as well as the untimely inconvenience for its customers is reduced. In the event that a storm is being forecasted, the Libra Tower can be lowered to the ground level, similar to a ship lowering its sails, and avoid significant damage.
Once the storm has passed, the tower can be quickly raised and power restored.
This feature would be especially appreciated after a natural disaster like a hurricane or an earthquake when normal electrical grids are inoperative. Thus the Libra Tower can be installed not only in inland areas where the wind is economically viable for turbines but in remote areas where inclement weather and high winds are the noun.

The Libra Tower is geometrically designed by combining a primary base form of a 60 degree hexagon, superimposed with a 6 sided 60 degree pyramid tapering to the apex, the Libra Scales, and 2 old fashioned wagon wheels with a hand brake.

The dimensions of the structure axe mathematically proportionate; each side of the hexagon is 10 meters more or less, and the base of each corner of the pyramid is fixed at each vertex of the hexagon, and each corner of the pyramid, acting as braces, is at a 60 degree angle. Thus the skeletal lattice structure of each corner to the apex is then 20 meters more or less. This proportion permits a tower to be emplaced in the centrality of the pyramid at a height of 35 meters, more or less. The basic building component of the tower is a rectangular pre-fabricated lattice structure, the width and depth are varied according to the tensile strength that is needed, each is 10 meters in length, each with the capability of interlocking with an add-on lattice. This basic building component is ideal for mass production.

In order to emplace the tower centrally in the center, the basic pyramid structure is halved, each half resulting in a 3 sided pyramid and between each half is a vertical and horizontal passage-way throughout of 2 meters, more or less, permitting the tower to be installed vertically and also allow for its limited rotation, the whole complemented by its necessary support structure.

The altitude of each half pyramid structure, the distance from the apex to the base, is 17.3 meters, more or less, and this altitude represents one half, more or less, of the total height of the tower to be 35 meters, more or less. Two face to face vertical support structures in the passageway center support the tower, which is fixed at the center by a sufficiently large, permanent horizontal fulcrum axle, that is on a reinforced plate, below each apex of the pyramidal braces. This axle holds the Libra Tower in place centrally and it also cohesively bridges the two halves. A second removable horizontal axle, of similar diameter is installed at the base above the ground level, and fixes the tower in a vertical mode when operating, and when removed, the tower is free to rotate to an obtuse angle of 150 degrees more or less to a servicing mode. There the turbine can be sheltered during cold and snowy weather conditions and servicing can proceed.

Each axle is secured according to earthquake standards so as to absorb the vibrations from the propeller rotors and even minor earthquakes. A buttress at the base keeps the base of the tower from over passing the center when it is being raised vertically. The top of the tower can be customized to fit whatever design the turbine base has in order to fit congruently.

The Libra Scale feature of the Libra Tower is the ballast inserted at the base that is equal in weight, more or less, to the weight of the turbine. The turbine may weigh 750 kilograms, for example and to achieve balance when in rotation, the ballast must be introduced in the base structure that is equal to the weight of the turbine, more or less.
The ballast at its base contributes greatly to the stability of the tower.

The tower structure is reinforced to support the extra weight of the turbine and the ballast, especially when in a horizontal position. This is attained by two "bridge"
trusses, one on the upper side and one on the lower side of the tower. The two trusses are supported by a perpendicular diametric arm from the fulcrum axle, and complemented with the lattice framework radiating to both ends that strengthen and stabilize the tower.

The third feature of the Libra Tower is a simulated wagon wheel on each side of the tower on the fulcrum axle, acting as a brake and support.
The rim of the wheels are the brake drums and each wheel has 2 brake pads adjacent to the rims that are secured on the stationary rectangular structures supporting the tower.
The brakes on the wheels have cables directly connected to the hand brake at ground level and can be activated by an operator so that the turbine is lowered very slowly or brought to a complete stop. This an essential safety component.

Winch cables attached to the front bumper of an utility vehicle are used to raise or lower the tower. The cables are attached to secure appendages on the top and at the base of the tower.

Description

PATENT PROPOSAL
~.IBRA T~~VEI~
for W~NND TURBINE
A Tower which has the additional feature of lowering the 'Turbine to ground level for repair Name: Alfred L.114athieu. PhD.
m~
signatur a Date: September 15, 2004 Inventor: Alfred L. Mathieu Cover Page 1 of 2 Owner: Alfred L. Mathieu , Agent: nil Title: LIBRA 'TONER F(JR ~INf? TURBINE
Synopsis - cover,page.
Modern wind turbine generators are usually mounted on ~ 50 meter high tower, more or less, normally constructed of joined cylinders to the desired height and firmly secured to a cement foundation. Such towers are very rigid. In most instances an industrial crane is required to hoist each cylindria~al segment into place and finally the turbine is hoisted on top of the tower. When an internal repair to the turbine is needed, an industrial crane is required to remove the turbine to ground level and then, after servicing, to re-install it at the top. An industrial crane can be very costly to accomplish this task.
The proposed patent for the Libra Tower which is assembled by interlocking multiple pre-fabricated lattice components is not rigid. The Libra Tower is designed for intermediate direct drive turbine systems with an output of wind AC energy of 300 to 500 kilowatt capacity, more or less, for a tower height of 35 meters, more or less. An industrial crane is not needed to install or repair the Libra Tower. It is capable of being installed and operating in remote or isolated areas of Canada.
The Libra Tower's primary function is to be the tower upon which the wind turbine sits in a rotatable horizontal mode so as to capture the maximum wind energy.
Its secondary function is to facilitate needed repairs and maintenance on the wind turbine by having the feature of easily lowering the turbine, without removing the wind turbine, to ground level and after the needed travail, easily raising the tower with turbine to its vertical operating position without an industrial crane. It can also be lowered just before severe winds are forthcoming so as to prevent damage and quickly raised to the operating position once the storm has passed.
This secondary function greatly reduces the "down time" of the turbine and becomes a critical economic factor when the tower is operating in remote areas, in inclement weather such as snow, freezing temperatures and high winds and where families are dependent on its electrical output.
The Libra Tower is constructed with pre-fabricated components, and is transportable in a standard wheel truck trailer. It is easy to assemble on site in 3 days more or Less. It can be located in remote locations that have high winds and would be welcomed by the indigenous community.
Initials Page 1 of 9 LIBRA T~WER FOR WII~zD TURBINE
I)ISCLOSLIRE
a) Field and Background of the Invention 1. Modern towers for wind turbine generators are being built at a higher and higher height - 50 meters more or less -- deemed nece ssaa-y not only to attain the maximum energy from the wind but to accommodate longer propeller blades - 25 meters more or less - in order to increase the generating capacity of the turbine.
The higher the tower and the longer the rotor diameter is the trend today in Europe for wind turbines.
Individual wind tower turbines are rare. Commonplace are wind fauns with several to as man as hundreds, even thousands of turbine towers, either along the coast line as in Denmark, England, Sweden and ~iolland or inland as in California.
The use of wind power to replace fossil fuels for electrical energy has been a priority for many years in European countries such as Denmark, Spain, France, Sweden and the L1K. The manufacturers have developed sophisticated wind turbines with features such as direct drive, AC current and digital controls.
European are the main designers and manufacturers of modern high tech direct drive AC wind turbines with towers as high as 70 meters, more or less and propeller blades 30 meters in length, more or less. Ciamesa Eolica of Spain can provide a product range ofturbines with a rated power from 660 kW to 2.0 MW
with a rotor diameter ranging from 47 to 83 meters The United States has pioneered the classic wand vane multiple blade windmills that have been used since the early 1900's for pumping water in ranches and farms throughout the country. They are still available today.
The Tennessee Valley Authority (TVA) presently has three wind turbines on Buffalo Mountain, and each is capable of generating 660 kilowatts of electricity.
The turbines sit atop towers that are 213 feet tall and each turbine has 3 blades, each being 75 feet long. TVA is planning on expanding the wind power project over time.
California is the state that has expanded the use of wind energy over the past years. As of 1999, the Tehachapi Wind Resource area in Kern County is the largest wind energy producer in the world with over 4,600 wind turbines collectively producing 1.4 billion kilowatt-hours of electricity per year.
The Palm Spring Wind Energy project in southern California has over 4,000 separate windmills, and generate sufficient electricity for Palm Springs and the Initials~~~ Page 7 of 9 entire Cochella valley. The largest tower with turbine stand I50 feet tall with propeller blades as long as 75 feet, and the high tech megatowers are engineered in cooperation with NASA and nursed by federal and state subsidies.
China is seeking to supply large wind turbines that are cost effective and reliable in operation to meet the growing demand of wind farms in the country. Since 1986 wind farms have been constructed with an installed capacity of 14 MW in various areas of Ghina. It has been analysed that the S00 KW wind turbine is the commercially economic type that is favored for manufacture and use for its planned wind farms. It is intent on establishing demonstration and experimentation wind farms to determine the optimum turbine capacity for the different wind velocities in the country.
China's goal din 1995) was to upgrade its installation capacity to 100 MW
annually.
Canada has been slow to adopt wind power as an energy source but is now progressing hurriedly. Its total installed wind turbine capacity in the provinces of Alberta, British Columbia, Saskatchewan, ~ntario, Quebec and the Yukon is currently 341 MW. There apparently is no wind turbine installations in Newfoundland/Labrador, New Brunswick, cat Manitoba, Territories of the North West and Nunavuk.
Patent Search A preliminary patent search of the Canadian and USA data base did not show any towers patented similar to the Libra Tower or any of its features.
The Niche for the Libra_Tower The use of wind power is expanding exponentia:tly in the industrial world and with the adaptation of modern technology, there is much competition.
The Libra Tower for wind turbines is designed mainly for the rugged rural areas of Canada where inclement weather is the norm and tolerated. It is designed to compete in the intermediate class having direct drive turbines producing AC
electricity in the range of 300 to S00 kilowatt capacity with a tower height of 3S
meters more or less.
'The tov~~er is suitable and adaptable fox certain developing countries and provides a technology that can be maintained by the local community. While the assemblage of the tower is easily transportable, however many of the components can be man~,afactured Locally in the selected developing countries.
Initials'~~ Page 8 of 9

Claims

The Technology of the Invention i which an Exclusive Property or Privilege is Claimed is defined as Follows:

The Libra Tower for Wind Turbine

1. The exclusive properties claimed for the Libra Tower arse a) It has dual functions; primarily as a standard tower for a wind turbine generator and thus be in a vertical non-rigid operating mode;
secondarily, the tower serves as a rotating beam so that with the turbine remaining at the top it can rotate easily from its upright vertical operating mode position downward 150 degrees, more or less, to near ground level position, more or less, for maintenance services, then rotated back up to the upright position. This ability greatly reduces the "down time" of the wind turbine which can be a significant economic factor and lessens the hardship to families dependent on the tower for electricity.
An industrial crane is not required like it is for repairing turbines on modern rigid high cylindrical towers.

b) An exclusive property is claimed for the ballast, equal to the weight to the turbine, more or less that is added within the base structure of the Libra Mower. The tower is then in balance when it is rotated to ground level, more or less, hence the Libra Scales. When the tower is in a vertical operating mode, the ballast at the base of the tower provides extra stability especially when operating in inclement weather.

c) An exclusive property is claimed for the braking system of the Libra Tower that ensures that the rate of descent of the tower is controlled as it rotates slowly, or come to a complete stop. This safety technology is incorporated in the tower and is a necessary feature. The braking system consists of a large wheel secured firmly on each side of the tower at its fulcrum axle and it is the outer wheel rim, not the inner drum as in vehicles, which acts as an outer drum for the 2 hydraulic/mechanical brake shoes that are fixed permanently on the vertical support structure of the tower. The wheels are also fixed to the upper and lower bridge truss supporting the tower ends. The mechanical hand brake that controls the braking is similar to the emergency brake in a vehicle, and is located at ground level, under the full control of the operator.

d) The Libra Tower is not rigid and absorbs the "yaw" movement of the turbine's propeller rotors according to certain earthquake standards.
At times, modern rigid towers have to replace the propeller and inner bearings of the turbine due to fatigue.

Certain Considerations:

The base of the "Libra" tower is the outline of two halves of a hexagon and the 4 skeletal braces are the corners of a 3 sided pyramid extended to the apex, each half centrally spaced for the tower itself. The 4 skeletal braces at the base are anchored to the concrete pad at the 60 degree vertex. This combination provides the maximum stability geometrically and economically.
The proportionate design can determine the structure for any reasonable lower or higher tower height that is desired.

The structural framework mainly consists of an interlocking pre-fabricated rectangular lattice that is normally fabricated locally. The mechanical framework for the tower and its auxiliaries of winches, and braking components are commonplace.

In contrast, modem towers are generally of a cylindrical design with a larger diameter at the base - can be 5 meters in diameter, more or less - and a smaller diameter at the top for the turbine. This design requires sophisticated manufacturers to fabricate, and then special trucks are needed to transport to the site.