Pump turbine, method of controlling thereof, and method of stopping thereof

A pump turbine comprising a runner, a shaft for transferring a torque of said runner to a generator motor, a water discharge controller for adjusting the quantity of water passing through said runner, and a governor for detecting a rotational speed of said runner and controlling said water discharge controller to set the rotational speed of said runner to a predetermined value in a steady state condition;

• wherein, upon a load rejection which shuts off said generator motor from an electric power system, said governor is controlled to make a target speed value of said runner only in the transient status immediately after a load rejection substantially higher than a target speed value in a steady status;
• said target speed value being a reference speed to be compared with actual speed so that said governor determines when and/or how to open or to close said water discharge controller in response to a balance between the two speeds.

A pump turbine comprising a runner, a shaft which transmits a torque of said runner to a generator motor, and a discharge controller which controls the quantity of water passing through said runner and capable of working in both Pump-up and Power Generation modes by switching the rotational direction of said runner;

• wherein said pump turbine further comprises a first governor which monitors the rotational speed of said runner in the Power Generation mode and controls the discharge controller to settle the rotational speed of the runner to a predetermined value in steady state condition and a second governor which controls the discharge controller in place of said first governor upon a load rejection which shuts off the generator motor from an electric power system and wherein the target rotational speed of said second governor is substantially higher than the target rotational speed of said first governor in the transient status at least just after a load rejection.

A pump turbine comprising a runner connected to a generator motor, a discharge controller which controls the quantity of water passing through said runner, and a governor which detects a rotational speed of said runner and controls said discharge controller to set the rotational speed of said runner to a predetermined value;

• wherein said discharge controller is closed after a load rejection and then reversed to open temporarily at least once so that the water flow is not reversed transiently even upon a rejection of a full load or nearly a full load.

A pump turbine comprising a runner connected to a generator motor, a discharge controller which controls the quantity of water passing through said runner, and a governor which detects a rotational speed of said runner and controls said discharge controller to set the rotational speed of said runner to a predetermined value;

• wherein said discharge controller is closed after a load rejection and then reversed to open temporarily at least once so that the water flow is not reversed transiently even upon a rejection of a full load or nearly a full load and so that a subsequent time period for the rotational speed returning to go down to said predetermined value by said governor is longer than a time period for the rotational speed increasing after a load rejection to arrive at a peak value.

A pump turbine comprising a runner connected to a generator motor, a discharge controller which controls the quantity of water passing through said runner, and a governor which detects a rotational speed of said runner and controls said discharge controller to set the rotational speed of said runner to a predetermined value;

• wherein said pump turbine further comprises a correction-controller for opening said discharge controller which is being controlled to close by said governor while the speed is decreasing in an accelerating manner over a peak immediately after a load rejection in the Power Generation mode.

A method of immediately stopping, in case of emergency, a pump turbine which comprises a runner connected to a generator motor, a water discharge controller for adjusting the quantity of water passing through said runner, a governor for detecting a rotational speed of said runner and controlling said water discharge controller and a correction-controller for giving some opening bias signals to said governor temporarily in a later stage of a speed increasing phase or in an earlier stage of a speed decreasing phase and which is running in the power generation mode;

• wherein said method comprises the steps of keeping both the governor and the correction-controller operative at least initially in the emergency stop process, fully closing said discharge controller and stopping the revolution of the pump turbine.

A method of immediately stopping, in case of emergency, a pump turbine which comprises a runner connected to a generator motor, a water discharge controller for adjusting the quantity of water passing through said runner, a governor for detecting a rotational speed of said runner and controlling said water discharge controller and a correction-controller for giving some opening bias signals to said governor temporarily in a later stage of a speed increasing phase or in an earlier stage of a speed decreasing phase and which is running in the power generation mode;

• wherein said method comprises the steps of keeping both the governor and the correction-controller operative at least initially in the emergency stop process, attenuating the undesirable influence of the S characteristics, fully closing said discharge controller and stopping the revolution of the pump turbine.

A pump turbine comprising a runner connected to a generator motor, a water discharge controller for adjusting the quantity of water passing through said runner, and a governor for detecting a rotational speed of said runner and controlling said water discharge controller to get a predetermined rotational speed of said runner, and a correction controller giving a bias signal for control of said governor in the opening direction temporarily in a later stage each of some successive speed increasing phases and/or in an earlier stage each of some successive speed decreasing phases after load rejection;

• wherein a set of operations to close and open said discharge controller is repeated several time in the transient state after load rejection.

A pump turbine comprising a runner connected to a generator motor, a water discharge controller for adjusting the quantity of water passing through said runner, and a governor for detecting a rotational speed of said runner and controlling said water discharge controller to get a predetermined rotational speed of said runner;

• wherein a means is provided by which the decreasing rate of the speed to return to the rated speed subsequent to its increasing after a load rejection is made adjustable independently from ordinary adjustment or control of said governor.

A pump turbine comprising a runner connected to a generator motor, a water discharge controller for adjusting the quantity of water passing through said runner, and a governor for detecting a rotational speed of said runner and controlling said water discharge controller to get a predetermined rotational speed of said runner;

• wherein the target rotational speed of said governor at each instant which is to be compared with actual speed at each instant is raised relatively quickly to follow the actual speed in said speed increasing step and lowered relatively slowly to be followed by the actual rotational speed accordingly in said speed decreasing step upon a load rejection which shuts off said generator motor from an electric power system.

A pump turbine comprising a runner connected to a generator motor, a water discharge controller for adjusting the quantity of water passing through said runner, and a governor for detecting a rotational speed of said runner and controlling said water discharge controller to get a predetermined rotational speed of said runner;

• wherein said governor is controlled to make the movement of the opening of said discharge controller draw a convex curve for a temporary opening at least when said rotational speed reaches the first peak or its vicinity upon a load rejection which shuts off said generator motor from an electric power system.

A pump turbine comprising a runner connected to a generator motor, a water discharge controller for adjusting the quantity of water passing through said runner, and a governor for detecting a rotational speed of said runner and controlling said water discharge controller to get a predetermined rotational speed of said runner;

• wherein the criteria of said governor to operate said discharge controller to open or close in response to the detected rotational speed is temporarily adjusted as a function of the detected speed so that said discharge reduction rate is made smaller in a convex curve of said rotational speed or its vicinity upon a load rejection.

A pump turbine comprising a runner connected to a generator motor, a water discharge controller for adjusting the quantity of water passing through said runner, and a governor for detecting a rotational speed of said runner and controlling said water discharge controller to get a predetermined rotational speed of said runner;

• wherein criteria of said governor to operate said discharge controller to open or close in response to the detected rotational speed is temporarily adjusted as a function of the detected speed so that said discharge controller is opened temporarily at least once before or while the speed decreasing subsequent to the speed increasing after a load rejection is proceeding in an accelerating manner and a flow reversal.after the load rejection is prevented.

A pump turbine comprising a runner connected to a generator motor, a water discharge controller for adjusting the quantity of water passing through said runner, and a governor for detecting a rotational speed of said runner and controlling said water discharge controller to get a predetermined rotational speed of said runner;

• wherein criteria of said governor to operate said discharge controller to open or close in response to the detected rotational speed is temporarily adjusted as a function of the detected speed so that said discharge controller is opened temporarily at least once before or while the speed decreasing subsequent to the speed increasing after a load rejection is proceeding in an accelerating manner and the time period for the rotational speed returning to go down to said predetermined value is longer than the time period for the rotational speed increasing after a load rejection to arrive a peak value.

A pump turbine comprising a runner connected to a generator motor, a water discharge controller for adjusting the quantity of water passing through said runner, and a governor for detecting a rotational speed of said runner and controlling said water discharge controller to get a predetermined rotational speed of said runner;

• wherein criteria of said governor to operate said discharge controller to open or close in response to the detected rotational speed is temporarily adjusted as a function of the detected speed so that said discharge controller is opened temporarily at least once before or while the speed decreasing subsequent to the speed increasing after a load rejection is proceeding in an accelerating manner and an upstream water hammering peak which occurs immediately after the rotational speed of said runner turns to decrease is eliminated.

A pump turbine comprising a runner connected to a generator motor, a water discharge controller for adjusting the quantity of water passing through said runner, and a governor for detecting a rotational speed of said runner and controlling said water discharge controller to get a predetermined rotational speed of said runner;

• wherein said governor further comprises a correction signal generator which supplies a correction value to said governor and said correction signal generator supplies a correction value to said governor so that the time period for the rotational speed returning to go down to said predetermined valve is longer than the time period for the rotational speed increasing after a load rejection to arrive at a peak value.

A pump turbine comprising a runner connected to a generator motor, a water discharge controller for adjusting the quantity of water passing through said runner, and a governor for detecting a rotational speed of said runner and controlling said water discharge controller to get a predetermined rotational speed of said runner;

• wherein said governor further comprises a correction signal generator which supplies a correction value to said governor and said correction signal generator supplies a correction value to said governor to eliminate an upstream water hammering peak which occurs immediately after the rotational speed of said runner turns to decrease by temporarily opening said discharge controller at least once before or while the speed decreasing subsequent to the speed increasing after a load rejection is proceeding in an accelerating pattern.

A pump turbine comprising a runner connected to a generator motor, a water discharge controller for adjusting the quantity of water passing through said runner, and a governor for detecting a rotational speed of said runner and controlling said water discharge controller to get a predetermined rotational speed of said runner;

• wherein criteria of said governor to operate said discharge controller to open or close in response to the detected rotational speed is temporarily adjusted as a function of the detected speed so that said discharge controller is closed immediately after a load rejection and then reversed to open temporarily during the closing at least once and the upstream penstock pressure is maintained nearly at a level as caused by the initial closing of said water discharge controller thereafter approximately until the speed decreasing subsequent to the speed increasing after a load rejection is proceeding in an acceleration manner.

A pump turbine comprising a runner connected to a generator motor, a water discharge controller for adjusting the quantity of water passing through said runner, and a governor for detecting a rotational speed of said runner and controlling said water discharge controller to get a predetermined rotational speed of said runner;

• wherein said governor further comprises a correction signal generator which outputs a value to correct a signal output from said governor and said correction signal generator outputs a correction value so that the time period for the rotational speed returning to go down to said predetermined value is longer than the time period for the rotational speed increasing after a load rejection to arrive at a peak value.

A pump turbine comprising a runner connected to a generator motor, a water discharge controller for adjusting the quantity of water passing through said runner, and a governor for detecting a rotational speed of said runner and controlling said water discharge controller to get a predetermined rotational speed of said runner;

• wherein said governor further comprises a correction signal generator which outputs a value to correct a signal output from said governor and said correction signal generator outputs a correction value to eliminate an upstream water hammering peak which occurs immediately after the rotational speed of said runner turns to decrease by temporarily opening said discharge controller at least once before or while the speed decreasing subsequent to the speed increasing after a load rejection is proceeding in an accelerating pattern.