Abstract: The present invention provides a method of culturing an alga that enables practical realization of low-cost and space-saving production of biofuels and bioenergy by culturing the alga using a reaction tank equipped with a digestive solution tank comprising digestive solution containing high concentration of nutrient salts, a membrane with a pore size of 0.45 µm or less and a culture tank comprising culture solution and the alga, which comprises consuming the nutrient salts by the alga in the culture tank to maintain the difference in concentration the nutrient salts between the digestive solution tank and the culture tank and supplying the nutrient salts contained in the digestive solution through the membrane into the culture solution by the diffusion depending on the concentration difference as well as an alga culture system therefor.

Abstract: A wind-turbine control device controls a wind turbine generator in which a rotor having a plurality of blades receives wind and rotates. The generator generates electrical power through the rotation of the rotor. The electrical power is supplied to a utility grid, and electric energy to be supplied to the utility grid can be changed according to a change in the frequency of the utility grid. The wind-turbine control device includes a subtracter to calculate a frequency change, which is the difference between a measurement value of the frequency of generated output power of the wind turbine generator and a set value of the frequency of the generated output power of the wind turbine generator. The wind-turbine control device further includes a limiter to limit a change in the electrical power corresponding to the frequency change calculated by the subtracter, based on the rotational speed of the generator.

Abstract: A wind power generator generates power through a rotation of a rotor and is interconnected, and operated with its power generation output previously limited in order to be able to further supply the power to a power system in response to a decrease in system frequency. Thus, a concentrated control system derives a required restricted amount corresponding to a power generation output required to respond to the decrease in system frequency, derives a value by subtracting an amount corresponding to a latent power generation output with which the power generation output can be increased, from the required restricted amount, and sets a restricted amount of the power generation output in each wind power generator to perform the operation with the power generation output previously limited to respond to the decrease in system frequency, based on the above value.

Abstract: To prevent disconnection of wind turbine generators due to changes in wind conditions even if the wind turbine generators is operated to limit the power output. A plurality of wind turbine generators that generate electric power by the rotation of rotors are provided in a wind farm are interconnected and are operated while the power outputs are limited in advance so as to be able to further supply electric power to a utility grid in response to a decrease in the frequency or voltage of the utility grid. The rotational speed of the rotor, which is a physical quantity related to increase and decrease in the power output of the wind turbine generator, is measured for each of the wind turbine generators by a wind-turbine control system, and the limitation amount of the power output of the wind turbine generator is set for each of the wind turbine generators by a central control system on the basis of the rotational speed of the rotor measured.

Abstract: A variable-speed power generator includes a prime mover that generates motive power by using natural energy; a wound-rotor induction generator that includes a stator having a primary winding and a rotor having a secondary winding, which are connected to a power grid, the generator generating electric power based on the motive power generated by the prime mover; a power converter connected to the stator and the rotor; and a controller controlling wound-rotor induction generator. The controller responds to instructions, sent by the power grid, for supplying reactive power to the power grid. The response of the controller to an instruction for supplying reactive power to the power grid may include imposing limitations on the reactive power supplied by the power converter to the power grid and causing the wound-rotor induction generator to operate at a rotation speed set higher than or equal to a synchronous speed.

Abstract: A variable-speed power generator includes a prime mover that generates motive power by using natural energy; a wound-rotor induction generator that includes a stator having a primary winding and a rotor having a secondary winding, which are connected to a power grid, the generator generating electric power based on the motive power generated by the prime mover; a power converter connected to the stator and the rotor; and a controller controlling wound-rotor induction generator. The controller responds to instructions, sent by the power grid, for supplying reactive power to the power grid. The response of the controller to an instruction for supplying reactive power to the power grid may include imposing limitations on the reactive power supplied by the power converter to the power grid and causing the wound-rotor induction generator to operate at a rotation speed set higher than or equal to a synchronous speed.

Abstract: A wind power generator generates power through a rotation of a rotor and is interconnected, and operated with its power generation output previously limited in order to be able to further supply the power to a power system in response to a decrease in system frequency. Thus, a concentrated control system derives a required restricted amount corresponding to a power generation output required to respond to the decrease in system frequency, derives a value by subtracting an amount corresponding to a latent power generation output with which the power generation output can be increased, from the required restricted amount, and sets a restricted amount of the power generation output in each wind power generator to perform the operation with the power generation output previously limited to respond to the decrease in system frequency, based on the above value.

Abstract: A wind-turbine control device controls a wind turbine generator in which a rotor having a plurality of blades receives wind and rotates. The generator generates electrical power through the rotation of the rotor. The electrical power is supplied to a utility grid, and electric energy to be supplied to the utility grid can be changed according to a change in the frequency of the utility grid. The wind-turbine control device includes a subtracter to calculate a frequency change, which is the difference between a measurement value of the frequency of generated output power of the wind turbine generator and a set value of the frequency of the generated output power of the wind turbine generator. The wind-turbine control device further includes a limiter to limit a change in the electrical power corresponding to the frequency change calculated by the subtracter, based on the rotational speed of the generator.

Abstract: The present invention provides a wind turbine generator and a blade pitch angle control method thereof in which an aerodynamic imbalance of a wind turbine rotor at the time of shutdown is further reduced, the maximum load of a wind turbine is further reduced, and the wind turbine generator can be reduced in weight and cost. The wind turbine generator includes a collective pitch angle controller 11 that produces a collective pitch angle demand that is common to blade pitch angles of wind turbine blades, an individual pitch angle producing unit 13 that produces an individual pitch angle demand inherent in each wind turbine blade, multipliers 21 to 23 that multiply the individual pitch angle demand by the individual pitch angle gain; an individual pitch angle gain producing unit 14, and adder 24 to 26 that add collective pitch angle demands to the output of the multipliers 21 to 23 and supply the same to pitch actuators 31 to 33 inherent in the wind turbine blades.

Abstract: A wind power generator generates power through a rotation of a rotor and is interconnected, and operated with its power generation output previously limited in order to be able to further supply the power to a power system in response to a decrease in system frequency. Thus, a concentrated control system derives a required restricted amount corresponding to a power generation output required to respond to the decrease in system frequency, derives a value by subtracting an amount corresponding to a latent power generation output with which the power generation output can be increased, from the required restricted amount, and sets a restricted amount of the power generation output in each wind power generator to perform the operation with the power generation output previously limited to respond to the decrease in system frequency, based on the above value.

Abstract: To prevent disconnection of wind turbine generators due to changes in wind conditions even if the wind turbine generators is operated to limit the power output. A plurality of wind turbine generators that generate electric power by the rotation of rotors are provided in a wind farm are interconnected and are operated while the power outputs are limited in advance so as to be able to further supply electric power to a utility grid in response to a decrease in the frequency or voltage of the utility grid. The rotational speed of the rotor, which is a physical quantity related to increase and decrease in the power output of the wind turbine generator, is measured for each of the wind turbine generators by a wind-turbine control system, and the limitation amount of the power output of the wind turbine generator is set for each of the wind turbine generators by a central control system on the basis of the rotational speed of the rotor measured.

Abstract: Reactive power is supplied in accordance with a reactive-power supply instruction from a power grid while ensuring a variable-speed range of a wound-rotor induction generator.

Abstract: Reactive power is supplied in accordance with a reactive-power supply instruction from a power grid while ensuring a variable-speed range of a wound-rotor induction generator.

Abstract: The present invention provides a wind turbine generator and a blade pitch angle control method thereof in which an aerodynamic imbalance of a wind turbine rotor at the time of shutdown is further reduced, the maximum load of a wind turbine is further reduced, and the wind turbine generator can be reduced in weight and cost. The wind turbine generator includes a collective pitch angle controller 11 that produces a collective pitch angle demand that is common to blade pitch angles of wind turbine blades, an individual pitch angle producing unit 13 that produces an individual pitch angle demand inherent in each wind turbine blade, multipliers 21 to 23 that multiply the individual pitch angle demand by the individual pitch angle gain; an individual pitch angle gain producing unit 14, and adder 24 to 26 that add collective pitch angle demands to the output of the multipliers 21 to 23 and supply the same to pitch actuators 31 to 33 inherent in the wind turbine blades.