CA2343876A1 - Power generation system - Google Patents

Power generation system Download PDF

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Publication number
CA2343876A1
CA2343876A1 CA002343876A CA2343876A CA2343876A1 CA 2343876 A1 CA2343876 A1 CA 2343876A1 CA 002343876 A CA002343876 A CA 002343876A CA 2343876 A CA2343876 A CA 2343876A CA 2343876 A1 CA2343876 A1 CA 2343876A1
Authority
CA
Canada
Prior art keywords
slip clutch
generator
rotor
magnetic slip
power
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
CA002343876A
Other languages
French (fr)
Inventor
Nazir Dosani
Nizar Ladha
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
Original Assignee
Individual
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Priority to CA002343876A priority Critical patent/CA2343876A1/en
Publication of CA2343876A1 publication Critical patent/CA2343876A1/en
Abandoned legal-status Critical Current

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Classifications

    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F03MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03DWIND MOTORS
    • F03D7/00Controlling wind motors 
    • F03D7/02Controlling wind motors  the wind motors having rotation axis substantially parallel to the air flow entering the rotor
    • F03D7/0276Controlling wind motors  the wind motors having rotation axis substantially parallel to the air flow entering the rotor controlling rotor speed, e.g. variable speed
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F03MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03DWIND MOTORS
    • F03D80/00Details, components or accessories not provided for in groups F03D1/00 - F03D17/00
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00Energy generation through renewable energy sources
    • Y02E10/70Wind energy
    • Y02E10/72Wind turbines with rotation axis in wind direction

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  • Engineering & Computer Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Sustainable Development (AREA)
  • Sustainable Energy (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Control Of Eletrric Generators (AREA)
  • Wind Motors (AREA)

Abstract

A power generating system comprising a generator (12), rotor (18) and a magnetic slip clutch (14) for coupling the rotor to the generator. The magnetic slip clutch assembly slips so as to permit the rotational speed of the rotor to increase relative to the rotational speed of the generator and maintain a substantially constant torque at the generator.

Description

CANADA
APPLICANTS: NAZIR DOSANI and NIZAR LADHA
TITLE: Power Generation System Field of Invention This invention relates to a power generating system of the type in which a slip clutch drives an alternating current generator. This invention is more specifically concerned with such a system wherein the rotational torque of the clutch may vary widely and randomly due to changes in the speed of rotor. An example of such a power generating system is a wind-driven turbine or windmill.
Background of the Invention It is a continuing problem with the use of wind-driven turbines to provide a cost-effective method of smoothing the aerodynamic torque input so as to reduce torque fluctuations in the drive train from the turbine input to the generator and to improve the quality of the electrical power output. It is particularly desirable to improve the electrical power output to such an extent that the alternating current generator can take the form of a normal "utility-grade" synchronous generator. At present, most commercial windmills use an induction generator to provide a limited slip characteristic, which maintains drive-train torque fluctuations within acceptable limits:
Such generators can only provide the power quality of a synchronous generator by expensive modification.
The use of a synchronous generator would be of significant benefit for windmill users. However, use of a synchronous generator requires (and use of an induction generator would benefit from) compliance to reduce the magnitude of the transfer function between the aerodynamic input torque and the drive-train torque to reduce fatigue loading on mechanical parts and to smooth the electrical power output.
There have been several attempts to address the problem of excessive drive-train torque fluctuations. In particular, GB 2136883 describes a power generating system in which the rotor of a wind-driven turbine is coupled to an alternating current generator by a differential drive unit which cooperates with an electric or hydraulic machine to control the torque applied to the generator in response to speed changes of the rotor. The system includes a controller which responds to the speed changes in the rotor and which acts on the machine to cause it to act as a generator when the rotor speed increases and as a motor when the rotor speed decreases. While this system might reduce torque fluctuations, it is complex in that it requires a machine capable of rotating in opposite directions and an active controller, with a corresponding electrical control loop, for controlling torque as a function of speed. Further difficulties can arise due to the inertia of the machine itself preventing adequate smoothing of high frequency fluctuations. While this problem can be overcome by a modification to the control loop, this increases the complexity of the system still further.
United States Patent 5,140,170 teaches a method of using fluid controlled slip clutch to connect the rotor to the turbine. The method indicates that at certain wind speeds, the transmission assembly slips completely leaving the rotor without any load thereby causing a dangerous acceleration levels.
Furthermore components have to be changed for different amount of slippage.
OBJECT OF THE INVENTION

It is desirable to provide a power generating system with a transmission assembly capable of limiting torque fluctuations in a simple and cost effective manner Summary of the Invention According to the present invention there is provided a power generating system comprising a rotor ( 18) adapted to drive a magnetic slip clutch assembly (14) and an electrical generator (12), said rotor (18) being connected to the magnetic slip clutch assembly (14) and the magnetic slip clutch assembly (14) being connected to the generator {12), said magnetic slip clutch assembly ( 14 ), when energized, connects the rotor ( 18) to electrical generator (12). As the rotor increases in speed the power to the magnetic slip clutch assembly (14) is reduced whereby the slip clutch assembly is allowed to slip so as to permit the rotational speed of the rotor to increase relative to the rotational speed of the generator in such a manner as to maintain a substantially constant torque at the generator thus, the slippage effectively dumps excess energy, permitting a constant torque characteristic to be achieved at an output shaft thereof (32).
The invention is particularly suitable for a wind power generation system ( 10) in which the turbine comprises a rotor ( 18) having one or more blades attached to a hub and designed to convert the aerodynamic power of the natural wind into a mechanical torque and an angular velocity. The magnetic slip clutch (14) is then coupled to the rotor (18).
The turbine can comprise a single rotor, but may instead comprise two or more rotors with or without interposed stators and either mounted on a ...........~.., u.N"..~.....~,._.~.....W....a.._..~., b ..... ~ ..M....... ,_.
..,.~~...~...M.~a.~...~....N....,~..~~._......~~

single shaft or coupled together to rotate at different angular velocities.
The generator may be any suitable alternating current or direct current type, and may run at either the same or a different speed as the turbine. However, as mentioned above it is an advantage of the present invention that a normal synchronous generator can be used.
Many wind power generating systems include a pitch control mechanism for altering the pitch angle of the turbine blades to maintain power at a fixed level when the available wind power exceeds that level. Periodic and random variations in the wind speed as it strikes the blades make close power control difficult. The quality of power control depends on the drive train and generator arrangement, in particular on the number of controllable variable parameters. In one conunon arrangement, rotor speed is preset by the grid into which electrical power is fed by an AC generator and a rigid drive train. In this case therefore the pitch is varied in response to changes in electrical power output. As the speed cannot be varied there is little or no inertial damping possible and power can only be controlled to within plus or minus 25%.
In the arrangement described in the above referenced Patent GB 2136883, both torque and speed are actively controlled, with slip energy being recovered and transferred to or from the interface with the electrical grid.
To maintain very tight control could cause system instability between torque and speed control loops. Therefore speed is allowed to vary within plus or minus 5% and power similarly varies within plus or minus 5%. However it has been noted by the present inventor that if a constant torque is maintained at the drive train, speed can be controlled to within plus or minus 2%. With such a small range of variable speed operation, the turbine can operate efficiently solely on the basis of rotor speed control rather than power control, therefore simplifying the control system. The power generating system can be set up for rated power by suitable adjustment of the control device. By providing an inherently constant torque operation at rated power, the gearbox manufacturer can reduce gear sizing, with cost advantages.
Brief Description of the Drawings In drawings which illustrate by way of example only a preferred embodiment of the present invention, Figure 1 is a block diagram of one embodiment of the present invention;
Detailed Description of the Invention As shown in Figure 1, in one embodiment the present invention comprises a power generation system comprising of rotor ( 18) connected to magnetic slip clutch (14) via drive shaft (30). The magnetic slip clutch (14) is connected to gearbox (24) via drive shaft (32) and gearbox (24) is connected to a generator (12) via drive shaft (34).
In the initial state the magnetic slip clutch (14) is disengaged to allow free rotation of rotor ( 18). This action allows the rotor ( 18) to get up to speed in low wind speeds. When the rotor gets to over 140 RPM the magnetic slip clutch (14) is fully engaged to drive shaft (32). Gearbox (24) amplifies the rotation of drive shaft (32) to 1845 RPM for drive shaft (34), thus the generator (12) coupled to drive shaft (34) rotates at 1845 RPM and generates power for consumption via grid connection (22).
The increase in rotor RPM due to high wind speed is noted by controller (20), which reduces the power to the magnetic slip clutch (14) via interface circuit (16), the magnetic slip clutch (14) starts to slip and reduces the rotational speed of drive shaft (32), which in turn reduces the rotation speed of generator ( 12).
The action of increasing/reducing the power to magnetic slip clutch ( 14) is controlled by controller (20) in response to RPM sensor (36) mounted in proximity to rotor shaft (30). As the speed of rotor shaft (30) increases the power to magnetic slip clutch (14) is reduced in proportion, and as the speed of rotor shaft (30) decreases the power to magnetic slip clutch (14) is increased proportionally until the magnetic slip clutch ( 14) is fully engaged.
In an alternate system, the magnetic slip clutch (14) uses spring loading to be fully engaged. The magnetic slip clutch ( 14) remains ftilly engaged via spring pressure until electrical power is applied. As the rotational speed of drive shaft (30) increase the input power to magnetic slip clutch (14) is increased proportionally to increase the amount slippage, thus the rotational speed of the generator is maintained at a constant level. Thus, only the excess power generated due to high wind speed is used to power the magnetic slip clutch (14). The nominal output power of the generator (12) is now used ( 100%) for consumption via grid connection (22).

Magnetic brakes (26) in combination with magnetic slip clutch (14) is used to hold the power generation system (10) in place during a storm or during system maW tenance.
The controller (20) also contains a switching circuit to reduce flashing in a switching circuit, when coupling a power generator to utility power grid (22). The reduction, in flash, is achieved by monitoring AC sine waves of utility power grid and power generator for compatibility in frequency, amplitude and phase. The switching occurs when all monitored signals are, momentarily, equal in time.
A preferred embodiment of the invention having thus been described by way of example only, it will be apparent to those skilled in the art that modifications and adaptations may be made without departing from the scope of invention, as set out in the appended claims.

Claims (3)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN
EXCLUSIVE PROPERTY OR PRIVILEGE IS CLAIMED ARE
DEFINED AS FOLLOWS:
1. A power generating system comprising:
a rotor (18) adapted to be driven by wind, a magnetic slip clutch assembly (14), and an electrical generator (12), said rotor being connected to the magnetic slip clutch assembly and the magnetic slip clutch assembly being connected to the generator, said magnetic slip clutch assembly is operable to control the amount of slippage to control the rotational speed of generator, and in the first state the magnetic slip clutch is fully engaged to transmit torque from the rotor to the generator via the magnetic slip clutch assembly with substantially zero slip in said magnetic slip clutch assembly, and in the second state the magnetic slip clutch assembly slips so as to permit the rotational speed of the rotor to increase relative to the rotational speed of the generator in such a manner as to maintain a substantially constant torque at the generator.
2. A system as claimed in claim 1, in which the magnetic slip clutch switches from the first state to the second state in response to the rotational speed of the rotor.
3. A system as claimed in claim 2, further comprising means for varying the slippage within the magnetic slip clutch in response to electrical load parameters.
CA002343876A 2001-04-17 2001-04-17 Power generation system Abandoned CA2343876A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CA002343876A CA2343876A1 (en) 2001-04-17 2001-04-17 Power generation system

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CA002343876A CA2343876A1 (en) 2001-04-17 2001-04-17 Power generation system

Publications (1)

Publication Number Publication Date
CA2343876A1 true CA2343876A1 (en) 2002-10-17

Family

ID=4168816

Family Applications (1)

Application Number Title Priority Date Filing Date
CA002343876A Abandoned CA2343876A1 (en) 2001-04-17 2001-04-17 Power generation system

Country Status (1)

Country Link
CA (1) CA2343876A1 (en)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1775465A2 (en) 2005-10-13 2007-04-18 General Electric Company Device for driving a first part of a wind energy turbine with respect to a second part of the wind energy turbine
WO2010075837A3 (en) * 2008-12-16 2010-10-21 Schaeffler Technologies Gmbh & Co. Kg Apparatus in a wind power plant for reducing overloads
EP3961029A1 (en) * 2020-08-26 2022-03-02 General Electric Company System and method for controlling a wind turbine
EP4008897A1 (en) * 2020-12-02 2022-06-08 General Electric Renovables España S.L. System and method for controlling a wind turbine
EP4083421A1 (en) * 2021-04-29 2022-11-02 General Electric Renovables España S.L. System and method for slip detection and surface health monitoring in a slip coupling of a rotary shaft

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1775465A2 (en) 2005-10-13 2007-04-18 General Electric Company Device for driving a first part of a wind energy turbine with respect to a second part of the wind energy turbine
EP1775465B1 (en) * 2005-10-13 2015-09-30 General Electric Company Device for driving a first part of a wind energy turbine with respect to a second part of the wind energy turbine
WO2010075837A3 (en) * 2008-12-16 2010-10-21 Schaeffler Technologies Gmbh & Co. Kg Apparatus in a wind power plant for reducing overloads
EP3961029A1 (en) * 2020-08-26 2022-03-02 General Electric Company System and method for controlling a wind turbine
US11486356B2 (en) 2020-08-26 2022-11-01 General Electric Company System and method for controlling a wind turbine
EP4008897A1 (en) * 2020-12-02 2022-06-08 General Electric Renovables España S.L. System and method for controlling a wind turbine
US11698053B2 (en) 2020-12-02 2023-07-11 General Electric Renovables Espana, S.L. System and method for controlling a wind turbine
EP4083421A1 (en) * 2021-04-29 2022-11-02 General Electric Renovables España S.L. System and method for slip detection and surface health monitoring in a slip coupling of a rotary shaft
US11913429B2 (en) 2021-04-29 2024-02-27 General Electric Renovables Espana, S.L. System and method for slip detection and surface health monitoring in a slip coupling of a rotary shaft

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