A 15MW wind farm on the coast of Hibikinada, Japan, came on stream in March 2003. The wind farm supplies power to Kyushu Electric Power Co. using ten 1.5MW wind turbines from GE Wind Energy. The turbines are expected to generate 35 million kWh annually, enough to supply 10,000 average Japanese homes.
The project is located in the bay area approximately 10 miles NW of Kokura City, Japan and within one of the major districts in Kitakyushu City. Groundbreaking for the project began in October 2002.
JAPANESE GOVERNMENT PROVIDES PART FUNDING
Funded in part by the Japanese government to encourage renewable energy, the Hibikinada Wind Farm is owned by NS Wind Power Hibiki Ltd. The company is in turn owned by Nippon Steel Corporation, Japan Wind Development (JWD), Torishima Pumps and Mitsui & Co.
The farm is sited on land leased from Kitakyushu City. Nippon Steel constructed the towers for the turbines.
ACTIVE YAW AND PITCH REGULATED DESIGN
The ten 1.5MW wind turbines are active yaw and pitch regulated with power/torque control capability and an asynchronous generator. The yaw system is electro-mechanically driven with wind direction sensor and automatic cable unwind. Power is varied using active-blade pitch control. The blade pitch angle is continually adjusted for optimum rotational speed and maximum lift-to-drag at each wind speed.
This “variable speed” operation ensures the turbines work at high efficiency, while fixed speed wind turbines only reach peak efficiency at one wind speed. And, while constant speed rotors must deflect high wind gust loads, GE Wind Energy’s variable speed operation absorbs the loads from the gust and converts them to electric power. Cut-in and cut-out wind speeds are 3m/s and 25m/s respectively. The three blades give a rotor diameter of 77m with a swept area of 4,657m². Rotor speed is variable between 10.1rpm and 20.4rpm.
OVERSPEED IN STRONG, GUSTY WINDS
Generator torque in the turbines is controlled by the frequency converter. The turbine rotor can overspeed in strong, gusty winds to reduce torque loads in the drivetrain. GE’s turbines store the energy in gusts by accelerating the rotor. Operating speed range is notably wider than the “slip” range used by other wind generators, which produce heat rather than electric power when regulating power in strong, gusty winds.
The conversion system generates reactive power (current leading voltage) to improve transmission efficiencies and voltage stability, particularly useful in weak grid applications. It automatically maintains defined grid voltage levels and power quality in fractions of a second.
FAIL-SAFE BRAKING AND LIGHTNING PROTECTION
The wind generator’s fail-safe braking system has electromechanical pitch control for each blade (three self-contained systems) and a hydraulic parking brake. Lightning receptors are installed on blade tips, with surge protection for electrical components.
The turbines can remain on-line and feed reactive power to the electric grid right through major system disturbances. A Low Voltage Ride-Thru (LVRT) feature enables wind turbines to meet transmission reliability standards similar to those demanded of thermal generators.
Active damping of the entire wind turbine system gives less tower oscillation than constant speed wind turbines. Active damping also limits peak torque, providing greater drivetrain reliability, reduced maintenance cost and longer turbine life. The bedplate drive train design means that all nacelle components are joined on a common structure for durability. There is a three-step planetary spur gear system, with both generator and gearbox supported by elastomeric elements to minimise noise emissions.
GE WIND ENERGY
GE Wind Energy is a business unit of GE Power Systems. GE Wind Energy designs and manufactures wind turbines with rated outputs of between 900kW and 3,600kW.
Nippon Steel pursues a range of activities including plant fabrication and building construction, urban development, systems solutions services, new materials business, silicon wafer manufacturing, chemicals production and power supply.
Established in July 1999, Japan Wind Development Co., Ltd. of Tokyo is an international wind project developer.