Hitachi, Ltd.

Hitachi Service Engineering Co., Ltd.

Kenzyu Ogiwara

Takao Kuwabara

Yasuteru Oono

Hisao Inoue

Isao Yokoyama

Akihiro Sakayori

Shigeaki Hayashi

Tooru Osanai

Susumu Naganuma

Akira Brando

Teiji Ashida

Minoru Kawada

A variable-speed pumped-storage power generating system includes a variable-speed generator/motor, a frequency converter connected to an electric power system, and a pump/turbine driven by the generator/motor. The power generating system comprises an optimum rotation speed function generator calculating an optimum rotation speed of the motor for driving the pump, a speed detector generating a speed detection signal of the motor, a speed regulator receiving the output signals from the function generator and speed detector for generating an output correction signal, an adder adding the output correction signal to output command signal, a comparator comparing the output signal of the adder with an output power detection signal generated from a motor output detector and generating an error signal, and an output regulator controlling the excitation of the secondary winding of the motor through the frequency converter so as to decrease the output power error to zero, thereby controlling the output and rotation speed of the motor. The power generatign system also comprises an optimum guide-vane opening function generator calculating an optimum guide vane opening, a comparator comparing the output signal of the guide-vane opening function generator with a guide-vane opening detection signal from a guide-vane opening detector, and a guide-vane opening regulator controlling the opening of the guide vanes according to the result of the comparison.

Variable-speed pumped-storage power generating system

A method of operating a water-turbine or a pump water turbine in which, when the runner is idling for phase modification running or stand-by running, the main machine is tripped by means of a main machine tripping circuit when the flow rate of cooling water supplied to the seal portions of the runner is maintained below a predetermined limit for a predetermined period of time. The main machine tripping circuit is excited to become operative only after the pressure around the runner comes down to a level approximating the water pressure in the draft pipe.

Method of operating water-turbine or pump water-turbine

For rotating the runner of a fluid machine in compressed air atmosphere in the runner chamber after shutting off working water and feeding compressed air to the runner chamber to move the liquid level therein downwardly below the runner while discharging water remaining in the outer peripheral portion of the runner through a leak-water exhaust pipe following starting of pump-operation, an inlet valve opening detector is mounted and operatively connected to a leak-water exhaust valve controller for controlling a leak-water exhaust valve. Stable operation of the fluid machine in spinning-in-air mode can be achieved by opening the leak-water exhaust valve by means of the leak-water exhaust valve controller following lapse of a given period of time after the inlet valve is fully closed, to permit the water remaining in the outer peripheral portion of the runner to be discharged through the leak-water exhaust pipe.

Method for operating fluid machines in spinning-in-air mode

Prior to bringing a fluid machine to the condition of spinning reserve for practicing a phase modifier operation or for producing a so-called standby condition which permits immediate switch-over to a power-generating or pumping-up operation, the water level in a runner chamber is forced down by supplying compressed air, and then the runner is driven to rotate in compressed air atmosphere. In this process, the water in a casing is gradually discharged at a rate which is commensurate with the rate of supply of the compressed air so as to thereby prevent leaking of the water in the casing from a guide vane.

Method for controlling the operation of a fluid machine in spinning

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Hitachi, Japan

Kenzyu Ogiwara