• Teeter hinge
    low speed main shaft
    mechanical brake
    two-bladed rotor
    2.5 stage gear box
    gear coupling
    bedplate
    handling rail
    asynchronous generator
    turbine controller
    yaw housing
    Helicopter hoisting and landing deck
    Design for serviceability
    Yaw system – yaw control
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    The Condor 6’s central rotor pivoting bearing, called the teetering hinge, introduces a degree of freedom between the two-bladed rotor and main shaft which enables turbine control by yawing. The limited teeter angles combined with Condor’s low teeter hinge torsional stiffness greatly reduces peak and cyclical aerodynamic loads on the blades, drive train and substantially lowers blade O-P stresses. READ MORE

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    Condor 6’s low speed main shaft is flanged in front to the rotor and transmits rotor torque to the gearbox attached to its backside. Its large drive component turns in two-large grease-lubricated main bearings, each incorporated into an individual steel housing. The main shaft can be easily removed and reinstalled, a cost- and downtime-saving offshore feature that is enabled by horizontally split bearing housing supports with a removable upper section. READ MORE

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    This brake functions as a rotor lock for servicing and a fail-safe backup braking device to stop the turbine in the unlikely event of a total system yaw failure. READ MORE

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    The Condor 6 is an upwind turbine that consists of two aerodynamically optimized rotor blades rigidly connected to a central hub. Its blades are rather wide and characterized by an exceptional 136,3 m/s rated tip speed. At a rotor diameter of 120 metres, the Condor 6 is state-of-the-art in its class. READ MORE

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    The Condor 6 medium-speed drive system incorporates a custom-developed modular design 2.5-stage planetary type gearbox with total 1:35 step-up gear ratio. This novel service-friendly gearbox design was developed by a German drive system expert on the basis of tight prescriptions of reliability and serviceability. A key design feature minimizes the number of moving parts while preventing rotor induced bending moments from entering the gearbox. READ MORE

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    A gear coupling between the Main shaft and Gearbox is integrated within the gearbox's low-speed input side. Primary function of the Condor 6 gear coupling is to absorb slight shaft misalignment as means to protect the gearbox against the remaining rotor bending moments entering bearings and gear systems. The gear coupling supplements the functioning of the rotor teeter hinge, which has already absorbed a key proportion (more than 80%) of the unwanted rotor-induced loads and bending moments, see Teeter hinge.

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    Condor’s design engineers have developed a welded steel bedplate that is structurally stiff enough to accommodate all main components of the non-integrated drive system, which are mounted in a fixed way. A central bottom flange connects to the Yaw housing. The rear section of the bedplate has a rectangular opening that is large enough for lowering the generator if necessary; see: Design for serviceability. READ MORE

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    The Condor 6 is an upwind turbine, comprising two rather wide aerodynamically optimised rotor blades rigidly connected to a central hub, operating at an unusual 127 m/s rated tip speed. The rotor diameter is with 120 metres state-of-the-art in its class. READ MORE

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    The Condor 6 is equipped with an 8-pole air-cooled asynchronous generator featuring an air – air heat exchanger. Key benefits from this asynchronous generator are derived from the brushless, robust, and uncomplicated design. Since the Condor 6 is a variable speed turbine, its generator produces electric power at a continuous varying frequency. The asynchronous generator requires a full (AC-DC-AC) converter solution, meaning that 100% of the power generated has to pass through a power electronic converter, where it is converted into grid-compliant 50Hz or 60Hz electric power. READ MORE

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    The tip speed ratio λ is defined as the relationship between rotor blade tip speed and wind speed. To obtain maximum aerodynamic efficiency the Condor 6 operates with a constant λ between starting speed (cut-in) and rated wind speed. To achieve this constant λ value during turbine operation, the Condor 6 applies an advanced in-house developed control system with controller, generator and power electronic converter functionally and fully integrated. READ MORE

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    The cylinder-shape yaw housing is connected underneath the bedplate with a flanged bolt joint. Internally, this housing contains three hydraulic yaw motors, control and additional valves, and backup power accumulators in a sheltered enclosure. The yaw motors are equally spaced inside the yaw housing structure and their pinion gears drive a large matching yaw bearing with an integrated ring gear. The yaw bearing is flanged in between the yaw housing bottom and tower top. READ MORE

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    Condor 6’s nacelle incorporates a helicopter landing and hoisting deck, which is the nacelle roof. Hoisting as well as helicopter landing and take-off operations are performed once the rotor has been placed in a safe and locked horizontal position. Condor 6’s helicopter landing deck is a world’s first in the offshore wind energy industry. READ MORE

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    Condor 6 has been designed for high serviceability. The spacious nacelle provides service personnel with ample access to all main components while the nacelle’s front hatch with retractable drawbridge allows safe and easy external teeter hub access. READ MORE

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    The Condor 6 operates with a unique yaw power output control system that combines fixed blade angle with a capability to yaw the rotor plane smooth and gradually out of the wind at higher speeds. As the wind speeds increase, the initial full circle thereby changes into a projected eclipse of reduced area. This feature is in direct contrast to conventional two-bladed and three-bladed upwind turbines that are commonly equipped with a yaw system designed only to direct the rotor towards the prevailing wind direction. READ MORE

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    Lightweight

    The Condor 6 with its 6.1 MW installed capacity is a lightweight offshore wind turbine. The nacelle mass, including the helicopter deck, is only 256 tons, while the two bladed 125 meter rotor has a mass of only 69 tons. A low head mass has a number of added benefits extending from reduced manufacturing costs to additional mass and cost savings for the tower and support structure.

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    Simplicity

    Simplicity as a phrase for our Condor 6 wind turbine directly refers to its unique rotor concept comprising two blades and a limited flexibility teetering hinge. This helicopter type rotor design fundamentally differs from commonly applied rigid propeller-type rotors with three blades and without such a teetering capability. Our Condor 6 rotor concept choice as a key characteristic and major added benefit eliminates an otherwise required costly and complexity-enhancing rotor blade pitch mechanism. Instead, Condor 6 turbines use their yaw system for controlling power output by yawing out of the wind above rated wind speed and to continuously direct the rotor towards prevailing wind directions below rated wind speed.

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    Reliability

    Simplicity intrinsically contributes to enhanced systems reliability due to pitch mechanism elimination, fewer other main components and more robust blades. The geared drive train configuration is state-of-the-art and only proven components will be applied. All main components together are rigidly mounted onto a structurally very stiff bedplate in a non-integrated line arrangement. The robust but critical gearbox as a key design achievement is fully protected from wind forces related rotor bending moments. The teeter hinge absorbs over 80% of these loads before they can reach the drivetrain and a special gear coupling between main shaft and gearbox the remaining 20%. The gearbox is further protected from impact load variations and power overshoot torque effects by an asynchronous generator with advanced matching power electronic converter. Below rated wind speed this converter ‘softly’ but actively reacts to and controls any system torque change, whereas above rated wind speed a fixed torque level is maintained within predetermined limits.

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    Maintainability

    The innovative drivetrain concept enables external and internal main component inspections, including their opening if necessary for conducting onboard repairs. This built-in easy-service capability reduces turbine down time and offers substantial added cost savings compared with having to exchange components, assemblies or even a complete nacelle. Inspections and onboard repairs are enabled by a number of distinct drive train built-in features. A horizontally split main gearbox casing offers full internal access to the low-speed stage bearings, shafts and gears, whereas the flanged medium-speed second gear stage can, if necessary, be removed separately. A horizontally split housing solution is also being applied for each of the two main shaft bearing supports. Furthermore, an opening in the nacelle bedplate rear part allows the lowering of even the heaviest drive train component with the aid of a handling rail and a heavy-duty patent pending elevator system. The rotor assembly including the blades is finally attached to the main shaft by a bolted-flange joint. It can be dismantled and lowered, hoisted and re-mounted again and all in horizontal position by employing the same elevator.

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    Accessibility

    The patent pending helicopter hoisting deck is integrated part of the Condor 6’s nacelle roof, while for a safe approach and safe turbine access the rotor can be locked in horizontal position. Both distinct design features have reduced helicopter deck integration costs dramatically compared to three-bladed turbines with such a structure located at the nacelle rear. The latter positioning is necessary to minimise helicopter collision risk while by definition always at least one blade extends above the helicopter hoisting deck in three-bladed wind turbines.

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    Efficiency

    The Condor 6’s patent pending control system allows increasing the rotor speed even beyond the rated speed, as the two-blade concept has eliminated traditional pitch bearings. The latter could under such high rotational speed conditions be exposed to excessive centrifugal loads. The airfoils have further been designed with a large chord length and high thickness characteristics in order to meet the highest aerodynamic efficiency, see Condor 6 power curve and annual energy production sheet.

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    Economics

    Condor 6’s distinct design simplicity, minimised head mass, enhanced reliability, superior efficiency, easy accessibility and service friendliness combined enables the highest possible costs of energy performance measured over a 25-year operational lifetime.

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    Lifetime

    Condor 6 turbines are designed for a 25-years operational lifetime. Damage equivalent loads are infamous key fatigue life contributing factors, and these are known to be much lower for two-bladed teetering hinge turbines compared to three bladed rigid rotor turbines. This offers huge opportunities for a mid-life technology retrofit as a cost-effective means to safely and effectively extend turbine’s operational lifetime.

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    Extreme winds

    In extreme environmental conditions, such as hurricanes, or typhoons, the Condor 6 turbine can be parked in a safe configuration to reduce the wind loads on the rotor dramatically, without the need to over-size critical components. In such a configuration, the rotor is locked with the blades in a horizontal position and with the blade tip kept pointing continuously into the wind by the yaw system in order to minimize the loads on the rotor.

Setting new standards for wind turbine performance and economics

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CONDOR WIND ENERGY LTD

Condor Wind Energy is the world leader in two-bladed wind turbine technology. Condor is set to bring about a revolution in the wind energy industry by setting new standards for wind turbine performance and wind farm economics.

Its turbines offer considerable advantages over traditional three-bladed turbines, in terms of price, performance, robustness, and reliability, especially when deployed in high wind regions and offshore.

Condor’s two-bladed turbines are different from traditional three-bladed turbines. They use a flexible “helicopter-type” of rotor, rather than the rigid “propeller-type” rotor used in three-bladed turbines.

Although the engineering issues involved in the design of two-bladed turbines are complex, the turbines themselves are characterised by their simplicity and robustness.

Condor will shortly launch its “Condor6” wind turbine, a 6MW, IEC Class 1A wind turbine designed for offshore deployment.

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