Abstract: A variable-speed pump system comprising: a hydraulic machine having a flow adjusting means and including at least a pumping function; a rotary machine operatively connected to the hydraulic machine and including at least a motor function for rotating the hydraulic machine; a frequency converter for driving the rotary machine; and a control system for controlling variable-speed operation of the rotary machine according to a command signal from an external unit. The pump system also includes an electric power control system, a flow adjustment control system, and a rotational speed control system. The power control system has a negligibly small time constant, compared to the time constant of the rotational speed control system.

Abstract: A method of detecting a counterflow in a pump comprises providing with detecting means for detecting variations in the discharge pressure of the pump and signal analyzing means for analyzing oscillation components contained in an output signal from the pressure detecting means, and detecting the pump's operating point to have entered a counterflow characteristic operation region when a waveform of the detection signal generated in association with the variations in the discharge pressure of the pump exhibits a predetermined spectrum distribution. Further, when it is detected that the operating point enters a counterflow characteristic operation region, the escape from that region is performed by temporally throttling the guide vane and temporally increasing the rotating speed.

Abstract: The operation of a variable speed electric driven pump turbine is monitored continuously during pumping to detect the operation point of the pump turbine, and to prevent it from falling into a hump characteristic region, which is recognizable on a graph of total dynamic head versus flow rate. Stalling occurs in the hump characteristic region as a result of a partial reverse flow of the water with respect to the runner. When the operation point of the pump turbine approaches the hump characteristic region, a corrective action is taken that includes increasing the output level of the electric driven pump turbine to increase its rotating speed, temporarily.

Abstract: A variable speed hydro-power plant includes a pump turbine (2) having a S-shaped characteristics at the turbine operation. A current time turbine operating point is grasped on a turbine characteristics diagram of the pump turbine (2). A limit operation characteristics curve (nr) of the pump turbine (2) is formed in advance so as to not reach the S-shaped characteristics turbine operation region. A reach of the limit operation characteristics curve (nr) is detected, a rotating speed (N) of the pump turbine (2) is lowered. An inrush of the pump turbine (2) into the S-shaped characteristics turbine operation region is eliminated, so the continuation of a stable and reliable turbine operation can be guaranteed.

Abstract: In an automatic control system including first and second control circuits, at least the second control circuit includes a proportional circuit and a differentiation circuit in addition to an integration circuit. When an object is controlled by switching from the first control circuit to the second circuit, an error signal between a target signal and a feedback signal is first applied to the integration circuit of the second control circuit, and after the lapse of predetermined time, the error signal is applied to the proportional circuit and the differentiation circuit of the second control circuit. With the constitution, jumping phenomenon is prevented which would be caused from the proportional circuit and the differentiation circuit.

Abstract: A control system for a variable speed water turbine generator apparatus includes a first function generator that is responsive to an output command signal. The first function generator produces a rotation number command signal. A speed adjuster produces an output signal in accordance with a different signal between the first function generator output and an actual rotation number. An adder adds the generator output command signal to the speed adjuster output signal to determine an overall output command signal. An output aduster produces an output signal in accordance with a difference between the adder output and an actual power output of the generator for controlling the firing angles of the frequency converter. A second function generator, responsive to the generator output command signal, determines an opening command signal for the variable opening vanes.

Abstract: 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.

Abstract: Disclosed is a control apparatus for a variable-speed hydraulic power generating system comprising a variable-speed a.c. electric generator connected to an a.c. electric power system and a hydraulic machine system including a water turbine for driving the generator and a guide vane for controlling an amount of water supplied to the water turbine.

Abstract: Disclosed in a variable speed pumping-up electrical power system comprising a variable speed generator/motor, a frequency converter connected between the generator/motor and an a.c. power system, a controller controlling an effective power input to the generator/motor by controlling the frequency converter on the basis of the difference between an actual effective power input from the a.c. power system and an externally-applied effective power command, and a correction circuit correcting the effective power command on the basis of the difference between the frequency of the a.c. power system and a frequency setting.

Abstract: In a water level depressing operation of a multistage hydraulic machine, first, the guide vane in the maximum-pressure stage is totally closed. Then, the respective guide vanes in the remaining stages are left opened more or less, and compressed air is supplied, whereby the water level is depressed below the runner in the runner chamber in the minimum-pressure stage. Thereafter, the respective guide vanes in the stages other than the maximum-pressure stage are also totally closed. Then, when the water level in each of the runner chambers is raised as a result of, for example, leakage of water from the associated guide vane, compressed air is individually replenished to each of the runner chambers.

Abstract: A fail-safe system is used in a control unit for opening and closing guide vanes of a pump-turbine apparatus operable in both of pump operation mode and turbine operation mode. The fail-safe system has a wire carried by a rotatable sheave adapted for transmitting an information concerning an opening degree of the guide vanes, a weight suspended from one end of the wire, an operation rod disposed below and in alignment with the weight in the direction of action of the force of gravity, and a change-over valve adapted to be switched by the operation rod. When the wire is cut off accidentally, the weight drops onto the operation rod to depress the latter to switch the change-over valve so that a servo-motor is switched to make the guide vanes close at predetermined rates of change of the opening degree in respective operation modes.

Abstract: A method and apparatus for controlling a variable-speed hydraulic power generation system using an induction generator of wound-rotor type is disclosed, in which variation in frequency of the power system connected to the power generation system or power demand from the power system is detected and the detected value is applied to a control unit for controlling the guide vane of a hydraulic machine driving the generator, thereby dampening variation in frequency or power balance of the power system.

Abstract: A method of and system for controlling a hydraulic turbine including a variable throttle valve located in fluid channel upstream or downstream of the hydraulic turbine adapted to be closed simultaneously as guide vanes of the hydraulic turbine are closed at a velocity higher than a predetermined velocity. The variable throttle valve is closed to a certain degree of opening in response to the sudden closing action of the guide vanes, but slowly opened to an original full open position after the guide vanes has closed to a predetermined degree of opening.

Abstract: An operation control method for a multistage regulated hydraulic machine wherein channels of the stages from the lower pressure side to the higher pressure side are successively communicated with each other through return guides and at least two said stages are provided with respective guide vanes capable of having their degrees of opening controlled in synchronism with each other.

Abstract: A rotary type pumping machine such as a pump turbine in a pumped storage hydro-electric plant, wherein, when the pumping operation of the runner of the machine is started, compressed air is introduced into the runner chamber to depress the water surface in the runner chamber to facilitate the start up of the runner and, when the runner is accelerated to a predetermined speed, the air in the runner chamber is discharged through an air discharge valve to commence the pumping operation. Water pressure available in the water passageway on upper reservoir side of the runner chamber is applied to the valve closing mechanism of the air discharge valve. The valve opening force exerted by a valve operating mechanism and acting on the valve opening mechanism of the air discharge valve is selected to be greater than the valve closing force generated by the water pressure applied to the valve closing mechanism of the air discharge valve.

Abstract: A method of controlling wicket gates of a pump-turbine which prevents abnormal hydraulic pressure variation when load carried on the pump-turbine is removed during the turbine operation thereof. The wicket gates are controlled to open when it is detected that discharge per unit head reduces with the reduction of speed per unit head. When it is once detected that the ratio of variation in the discharge per unit head to the variation in the speed per unit head is reversed from a positive value to a negative value, the wicket gates are closed.

Abstract: A method of controlling a pump-turbine having an S-section in its characteristic curve. The behavior of the operation point tracing up the S-section is judged and discriminated through detection of the rotation speed N of the pump-turbine or the acceleration dN/dt of the same. More specifically, it is judged that the operation point of the pump-turbine is tracing the S-section in the flow-rate reducing direction, through detections of the conditions that the acceleration dN/dt is materially negative and that the rotation speed N is greater than a predetermined speed. At the same time, it is judged that the operation point has commenced to trace the S-section in the flow-rate increasing direction, through detecting that the rotation speed has come down below the predetermined speed.

Abstract: A control apparatus comprises a primary control unit composed of wicket gates of a hydraulic turbine and a secondary control unit composed of a bypass valve which is operated to open or close in cooperation with the opening or closing of the wicket gates. First and second link mechanisms are provided between the wicket gates and a hydraulic pressure distributor valve which is operatively connected to the bypass valve to control opening or closing of the latter. The first link mechanism detects the opening or closing motion of the wicket gates and transmits the corresponding signal to the hydraulic pressure distributor valve for the bypass valve, while the second link mechanism detect position of a pressure distributor valve plunger for the wicket gates and transmits the corresponding signal to the distributor valve for the bypass valve.

Abstract: A method of controlling the wicket gates of a pump-turbine having in the turbine operation area S-section where discharge per unit head and torque per unit head reduce with the reduction of speed per unit head. The pump-turbine is incorporated in a hydraulic system together with at least one of other pump-turbines. A penstock includes a plurality of pipelines each extending from the upstream side of each of the pump-turbines, while a tailrace includes a plurality of pipelines each extending from the downstream side of each of the pump-turbines; and at least one of the upstream ends of the pipelines of the penstock and the downstream ends of the pipelines of the tailrace are connected to a common pipeline. Upon sudden removal of load from the pump-turbine having the S-section, the wicket gates are closed at an earlier timing so that the hydraulic pressure in the penstock may reach the maximum value before the pump-turbine initiates to operate in the S-section.

Abstract: A method for improving the starting phase of the running of a hydraulic turbine or pump turbine. According to this method, an opening of wicket gates is increased as a function of an increase in r.p.m. of a runner, so that the flow rate of water running into a runner may be maintained constant throughout acceleration and synchronizing process to the rated speed once attained said constant value at an early stage of starting.