FL20KWPITCH/SWT20 Small Wind Turbine for … · positive land mark, ... the control system secures the turbine by pitching the blades to a feathered ... 24 V for logic control and

FLEXIENERGY di Alessandro Giubilo Via Ostriana, 12 00199 Roma Tel.+39 068610173 Fax +39 0686389651

E-mail: info@ P.IVA 09286561007 C.F. GBLLSN66B27H501M

FL20KWPITCH/SWT20

Small Wind Turbine for Professional Use

The FL20KWPITCH is designed for demanding applications where reliability, efficiency

and life cycle cost are key factors.

**Please read carefully before use **



1. Introduction

FL20KWPITCH small wind turbine is designed to meet demanding requirements from professional users of stand alone or grid connected wind turbines. FL20KWPITCH is ideal for replacement of diesel generators at rural telecom base stations, water pumps, gasoline stations or farms. The FL20KWPITCH includes features and solutions for optimal power production, like active pitch and yaw together with variable speed operation. Systems for remote operation and monitoring ensure high availability, efficient maintenance and long service intervals. Carbon fibre blades and a direct drive permanent magnet generator are other features to meet the need from professional users.

2. Main characteristics Robust design The FL20KWPITCH is designed to comply with the IEC 61400-2 Ed. 2 standard for small wind turbines. Strength analysis has been performed for the entire mechanical design. FL20KWPITCH is designed for service intervals of 5 years. The low-speed, direct drive permanent magnet generator in conjunction with the robust axis and bearing design withstands loads at extreme conditions. There are no electrical connections to the permanent magnet rotor of the generator. Since both the passive pitch system and the passive yaw system are electromechanical no hydraulic system is needed that would require frequent service and may cause leakage.

Efficient power generation All components are chosen and designed with efficiency in mind. The highly efficient blade design together with passive pitch and variable turbine speed ensures that as much as possible of the incoming wind is transferred into power. The rotation is converted into electricity through a low-loss, direct drive permanent magnet generator. In the FL20KWPITCH an ultra sonic wind sensor is used together with a passive yaw control system to ensure optimum direction towards the wind.

Fail safe brake systems Safety is ensured by dual fail-safe braking systems; one aerodynamic brake and one electromechanical disc brake on the main shaft. There is special brake device that is turning angle of blades to minus direction while tighten steel braking wire. Wind force to wind blades generate a counterforce so that decrease slowly spin speed of blades to regulate speed and stop rotating, it can be automatically operation, also can be operated by manual.



Remote operation All systems are controlled by software; therefore remote control of operation and maintenance is possible ensuring high availability and few visits to the site, as well as monitoring wind utilization for optimal production.

Easy installation The weight of the nacelle and the carbon fibre blades are low which enable that mounting can be performed also by use of a small climbing crane. The blades can be handled by one person. Minimum bending of the rigid carbon fiber blades allows large tower or mast diameter. Standard tower is 15 m. As an alternative FL20KWPITCH can also be delivered with a 20m tower.

Silent operation The blades have been carefully designed in accordance with the latest technology. Made in carbon fibre reinforced resin with a thin and sharp rear edge, the blades move through the wind so smoothly you can hardly hear them.

Attractive design Large effort has been put into creating a functional and attractive design. The gracefulness of the FL20KWPITCH makes it a positive land mark, creating interest and a positive image.



3. System overview

FL20KWPITCH Wind Turbine system consists of four major parts:

Nacelle with rotor and blades This part mounted on the tower or mast contains all moving mechanics, sensors, actuators and parts of the control system.

Tower or Mast The tower or mast is attached to the foundation, and the nacelle is mounted at the top. The manufacture has designed and verified mast and tower constructions. If another tower or mast is used, this must fulfill requirements stated in the installation manual.

Control and Power System cabinet The control and power system cabinet is located on the ground and consists of a computer with interfaces to control the mechanical parts of the system and power electronics to rectify the generated power and to convert this to the wanted power interface.

Foundation A foundation to support the tower or mast is required and must fulfill the requirements as specified in the installation manual. The ground upon or within which it is placed must also satisfy minimum force requirements. Preparation for electrical grounding of the tower or mast is also required.



Connection Drawing For Each Component



4. Technical description

General The FL20KWPITCH is a direct driven, variable speed, pitch controlled wind turbine. The direct drive approach means that the hub is directly connected to the generator without any gearbox. This improves performance, gives lower mechanical noise and increase the lifetime and service intervals of the turbine. Variable speed means that the rotational speed of the three blades connected to the hub are proportional to the wind speed. This will maximize the power output of the turbine, especially at low winds, and also gives the turbine a unique feature of being programmable to avoid certain speeds. This is very useful if there are any structural resonant problems at these frequencies. The electrically actuated pitch control system controls the angle of attack of all blades simultaneously. A passive pitch control of the turbine minimizes the cut in wind speed of the turbine, and also provides a way of optimizing the energy output of the turbine as a function of available wind energy. The pitch control also has two other important functions. It can be used to minimize forces on the structure (i.e. tower structure) by changing the angle of attack if there are any unwanted structural movements. The other important function of the pitch control is to act as a safety system by controlling the blade angle to avoid over-speed conditions and to pitch the blades to a feathered position during too high winds.

Variable speed The turbine speed ranges from 0 to 120 rpm and a maximum speed of 150 rpm is allowed during short periods of time. Power generation is started at 30 rpm where maximum power is reached at 120 rpm and a corresponding wind speed of 9 m/s.



Pitch control The electrically controlled pitch system consists of a pitching mechanism and a direct drive, brushless servo motor. If the pitch motor speed is the same as the turbine speed there will be no change in blade angle. If the speed of the motor is increased with respect to turbine speed, the angle between the blade and the rotation axis will increase and conversely if the speed of the motor is decreased the blade angle will be reduced. In case of a critical failure or loss of power, the pitch motor is short-circuited. This will cause the blades to be automatically feathered by the rotation of the rotor, which will then stop. (Pat. pending)

Direct drive generator The permanent magnet generator is directly connected to the hub and its rotor that holds the magnets is mounted on the main shaft. Since the stator of the generator is mounted into the aluminum house, directly exposed to the wind, an efficient cooling is achieved.

Yaw system The electrically controlled yaw systems primary function is to align the nacelle to the wind. By using a controlled way of aligning the nacelle, the turbine will start in very low winds, if compared by a turbine with a fin that requires the wind to be high enough to turn the nacelle. Another important function is to detect the number of turns of the nacelle and to start an “untwist” sequence to protect the cables running from the nacelle to the ground. The system is driven by a brushless PM motor. To protect the yaw system from high dynamic torques, a brake is located beneath the primary yaw gear.

Rotor disc brake The electrically actuated rotor disc brake serves both as an emergency brake and as a parking brake. The brake, together with the pitch system, forms two independent emergency braking systems. Normally, the rotor disc brake is used whenever the turbine has to be stopped completely. During high winds, above 20 m/s, the control system secures the turbine by pitching the blades to a feathered position and the rotor disc brake is then engaged. The rotor disc brake is also used during service and maintenance. Since the brake is used mainly as a parking brake, the wear on the pads is very low and are normally not to be replaced during the lifetime of the turbine. The disc brake relies on an internal battery backup system to work.

Control System platform The control system HW consists of an industrial PC with MS Windows XP Embedded, on which a Soft PLC system is running. The hardware is located in the Control and Power System Cabinet and communicates over Ethernet to the nacelle, and other parts of the system. The Control System platform contains tools for logging and storing selected data with selected time interval.



Power System The FL20KWPITCH can be configured in a variety of different power solutions, by changing the power cabinet located on the ground. In the standard version the SWT20 is equipped with power cabinet for grid connection which means that the turbine is connected to a grid and is delivering power when the wind is available. If the grid is lost, then the turbine will stop, avoiding power generation into the grid. Above figure shows the major parts of the power system. The permanent magnet generator is connected to an active rectifier that rectifies the three phases to a DC bus. The DC voltage is converted into a three phase voltage and fed into the grid. AS1 is the cabinet located on the ground and AS2 is the cabinet installed in the nacelle, containing the electronics to control the different nacelle systems. AS2 is fed by two different voltages, 24 V for logic control and 48 V as a power bus, powering all electrical motors. Both 24 and 48 V power is delivered from a battery bank, charged by the grid. The battery bank contains enough power to stop the turbine during short power losses of the grid.



5. Operation

Modes of operation The wind turbine system has four different modes of operation. 1. Init This mode is entered at the first power up of the system. Access to the nacelle is not allowed at any circumstances in the init mode. 2. Auto The SWT20 is manually set in the Auto mode. This is the normal mode of operation in which the software controls the turbine so that the electrical power generated is maximized with respect to the wind speed. Access to the nacelle is not allowed at any circumstances in the auto mode. 3. Secure The Secure mode can be entered manually by the user or if a critical error has been detected by the control system. All actuating systems are then shut down and the turbine is brought to a halt. Access to the nacelle by trained personnel is allowed in secure mode. 4. Manual The Manual mode can only be entered manually by the user. This mode is used during service or installation in order to test different functions in the system. Access to the nacelle by trained personnel is allowed. The software provides a GUI on site for the user to control the different functions. These functions can also be operated by using the buttons on the nacelle electrical cabinet.

Remote / Local Operation The different modes described above can be accessed either remote or locally on the wind turbine site. A key switch located in the control and power cabinet on the ground has to be set to enable remote operation.

Emergency stop system As mentioned in chapter 2 and 4 two independent brake systems provide the means of stopping the turbine in case of an emergency. An emergency stop is normally invoked by the control system detecting a dangerous event in the turbine but can also be triggered by the user. The control system constantly monitors all functions and will stop the turbine if any one of the following events occurs: 1. If the sensors sensing critical functions in the turbine shows abnormal or unpredictable results (i. e. wind sensor, turbine speed or yaw position sensor malfunction) 2. If the movement of the nacelle is abnormal (blade damaged, or any other mechanical unbalance). 3. If the turbine speed reaches above 150 rpm. 4. If a remote or local request to enter emergency stop is detected.

The turbine is also equipped with a watch dog system that detects the pace of the control system. If the control system breaks down, this system will stop the turbine immediately. Turbine speed is monitored by a separate system measuring the output voltage of the generator. If the speed is too high, this system will override the control system and stop the turbine.

Tower load control The nacelle is equipped with two accelerometer sensors, mounted so that the movement of the nacelle can be analyzed by the control system. High loads on the tower or mast can be avoided by utilizing the pitch control system together with the accelerometers.



System monitoring function The FL20KWPITCH monitoring function of the control system detects if any error events occurs. Each event is classified by a severity scale reaching from 1 to 3 where 3 is a severe error resulting in an emergency stop of the turbine. A class 1 fault indicates an error that requires attention but will not stop the turbine. A class 2 fault indicates an error that will stop the turbine but without any emergency procedures (normal stop). All faults are logged to file in the turbine control system and the latest error and status level is available via the remote communication parameters.



6. Maintenance

The components have been chosen to obtain a long maintenance cycle. Under normal conditions on-site maintenance should be performed with 5 years interval. Depending on the environmental conditions an additional on-site inspection should be performed with five years interval. Filters in the Control and Power Cabinet on ground have to be maintained according to local dust occurrence. The turbine control system enable remote control of Operation & Maintenance status. For this purpose ADSL or GSM/UMTS is used for communication to the centralized O&M system which is implemented on Microsoft dot Net. The communication includes configurable data for monitoring wind, power production, turbine RPM and other information from different sub systems. The data communication channel is also used for upgrade of turbine control system SW when needed. As an option, the nacelle can be equipped with a bearing vibration monitoring system. This system will detect early problems in the main bearings and has the capability to perform both trend and spectral analysis of the bearing vibration levels.



7. Performance data

Parameter Value Unit Cut-in wind 2 m/s Survival wind 55 m/s Rated power@ 9 m/s 20 KW Yearly production at 5 m/s average wind Appr. 50 MW

Power Curve FL20KWPITCH

Yearly energy curve FL20KWPITCH



8. Environmental characteristics

FL20KWPITCH is designed for ambient temperature -40…+50 degC and to be used in environmental corrosion stress category C3 with High Durability according to ISO 12944.

9. Mechanical data

Tower interface forces and torque Swept Area 120 m2 Rotor Diameter 12,35 m Nacelle length 2450 mm Nacelle width 700 mm Nacelle height 700 mm Weight complete Nacelle, with rotor and blades 960 kg Weight per blade 37 Kg Maximum Torque any wind 6 kNm Maximum axial force in operation up to 25m/s 6 kN Induced frequency band 1.5-6 Hz Maximum Turbine speed 150 RPM Maximum wind area C*A 6 m2

Flatness deviation over the surface less than 0.3 mm All dimensions are in mm



Rotor diameter: 12.35m Blades quantity: 3pcs Direction: Always downwind Blades material: Carbon fiber reinforced plastic Rated output: 20000W Power supplied to grid: 24000W (in 5seconds) working voltage: DC360V/500V,AC220V/380 Annual average energy production: 50MWH (in 5m/s wind speed) working wind speed: 3-35m/s Initial wind speed: 2.0m/s Nominal wind speed: 9m/s（16.88mph, 32,4 Km/h） Storm-stand: up to 55m/s Rated rotate speed: 120r/min Wind turbine type: Three-phase, PMG Alternator Working temperature: from -40 to +60 C Blade Pitch Control: Varies Pitch Over-speed Protection: Aerodynamic brake+ electromechanical disc brake Speed regulation methods: Yawing and electric magnet Switch Gearbox: None, Direct Drive Accumulators full charge time: about 8 hours



Maximum Tower Width



10. Tower Cables All cables are designed to withstand a maximum free hanging length of 20 m and has a limit of twist by 1 turn per meter. If longer cables are to be installed, a connection or clamping point has to be installed at this distance from the nacelle. The power and the Nacelle power cable are installed in screw terminals, both in the Nacelle and in the ground cabinet. The communication cable has a RJ45 connector at each end.

Cable interface to the Nacelle Area Ethernet communication CAT 5 cable Nacelle power cable provides the 24 and 48V 4*4 mm2 Power from the generator 5* 10 mm2



11. Control and Power Outdoor Cabinet

The Control and Power outdoor cabinet is designed for being attached to the tower or mounted on a separate foundation. The Control and Power cabinet is also available in an indoor version. The outdoor cabinet can be delivered in two different security classes, normal and high security. The high security cabinet has enhanced door locking system and a more advanced key system. The normal cabinet is designed for use in areas with low intrusion risk. The cabinet is isolated with a heating system for cold environment. Internal cooling fans evacuates the air from the cabinet direct to the outside. The cabinet is available in different colors

Cabinet depth 600 All dimensions are in mm Inner layout



12. Protection of power grid interface

When the FL20KWPITCH is configured for connection to the 3 phase 400V power grid the connection should be protected by 35 Amp fuses following parameters are measured continuously and if out of bound for longer period than allowed the FL20KWPITCH will turn into secure mode.

Power parameter Min Max Unit Duration Allowance Frequency 48 51 Hz 0,5 sec Voltage deviation (spike) -20% +20% V 0,2 sec Voltage deviation -10% +6% V 60 sec Reversed operation (motor drive) 5 sec Two blown fuses in the grid interface 5 sec One blown fuse in the grid interface No limit Power supplied to grid 24 kW 5SEC

13. Standards and directives

Designed and built according to IEC 61400-2 design rules. Designed to confirm with: Machinery Directive: 98/37/EC, standard: ISO 12100-2 Low Voltage Directive - LVD: 2006/95/EC, standard: IEC 60204-1 Electromagnetic Compatibility Directive - EMC: 2004/108/EC, standard: IEC 61000-3

Documents

FL20KWPITCH/SWT20 Small Wind Turbine for … · positive land mark, ... the control system secures the turbine by pitching the blades to a feathered ... 24 V for logic control and