Variable speed pumping-up system

Claim 1

A variable speed pumping-up system connected to an electric power system having means to pump water, having electric motor means for driving said pump means and having a regular control means for operating said electric motor means in a regular control state at a variable rotating speed as a function of current operating conditions of said pump means while receiving electric power from said electric power system of a given frequency, comprising: said pump means exhibiting a hump characteristic in an operating region thereof; and said variable speed pumping-up system including an overriding control unit, said overriding control unit having means for monitoring operating conditions of said pump means including rotating speed, guide vane opening and dynamic head so that, when an operation point of said pump means closely approaches said hump characteristic region during regular control by said regular control means, said regular control means is substantially interrupted, and an overriding control by said overriding control unit is commenced to provide an extra acceleration to said pump means temporarily so that a close approach of said operation point of said pump means to said hump characteristic region is avoided.

Claim 4

A method for controlling a variable speed pumping-up system, comprising: pumping water with pump means that exhibits a hump characteristic in a pump operation region thereof, said pump means having adjustable guide vanes; driving said pump means with motor means having a frequency converter and providing said motor means with electric power of a given frequency from an electric power system to drive said pump means in a regular control state at a variable rotating speed that is adjusted in accordance with actual operating conditions; calculating and storing beforehand model test data of said pump means including data of a starting point of said hump characteristic region as a function of dynamic head, the rotating speed of said pump means, and the opening degree of said guide vanes; detecting a degree of opening of said guide vanes and the rotating speed of said pump means so that said starting point of said hump characteristic region can be calculated in response to the detected rotating speed of said pump means and the detected degree of opening of said guide vanes over an operational range of said pump means; measuring an actual total dynamic head; calculating a difference between said starting point of said hump characteristic region and said actually measured total dynamic head so that when said difference has become smaller than a predetermined level, said regular control state is substantially interrupted and an overriding control for said variable speed pumping-up system is commenced to provide an extra output to said motor means and correspondingly to provide an extra acceleration to said pump means temporarily so that an operation of said pump means in a hump characteristic region is avoided.

Claim 5

A method for controlling a variable speed pumping-up system, comprising: pumping water with pump means that exhibits a hump characteristic in a pump operation region thereof, said pump means having adjustable guide vanes; driving said pump means with motor means having a frequency converter and providing said motor means with electric power of a given frequency from an electric power system to drive said pump means in a regular control state at a variable rotating speed that is adjusted in accordance with actual operating conditions; calculating and storing beforehand model test data of said pump means including data of a starting point of said hump characteristic region as a function of dynamic head, the rotating speed of said pump means, and the opening degree of said guide vanes; detecting a degree of opening of said guide vanes and the rotating speed of said pump means so that said starting point of said hump characteristic region can be calculated in response to the detected rotating speed of said pump means and the detected degree of opening of said guide vanes over an operational range of said pump means; measuring an actual total dynamic head; calculating a difference between said starting point of said hump characteristic region and said actually measured total dynamic head so that when said difference has become smaller than a predetermined level, said regular control state is substantially interrupted and an overriding control for said variable speed pumping-up system is commenced to provide an extra output to said motor means and correspondingly to provide an extra acceleration to said pump means temporarily so that an operation of said pump means in a hump characteristic region is avoided.

Claim 6

A method for controlling a variable speed pumping-up system, comprising: pumping water with pump means operating in a pipe line shared upstream or downstream with another means to pump water, said pump means exhibiting a hump characteristic in a pump operating region thereof; driving said pump means in a regular control state at a variable rotating speed with electric motor means in accordance with actual operating conditions, said motor means having a frequency converter and receiving a supply of electric power of a given frequency; commencing an overriding control over said pump means that substantially interrupts said regular control state when an operation state of said another pump means with which said pipe line is shared abruptly changes, said overriding control temporarily correcting said rotating speed of said pump means and thereafter releasing said overriding control after a water hammering phenomena caused by said abrupt change in the operation state of another pump means has settled.

Claim 7

A method for controlling a variable speed pumping-up system, comprising: pumping water with pump means operating in a pipe line shared upstream or downstream with another means to pump water, said pump means exhibiting a hump characteristic in a pump operating region thereof; driving said pump means in a regular control state at a variable rotating speed with electric motor means in accordance with actual operating conditions, said motor means having a frequency converter and receiving a supply of electric power of a given frequency; commencing an overriding control over said pump means that substantially interrupts said regular control state when an operation state of said another pump means with which said pipe line is shared abruptly changes, said overriding control temporarily correcting said rotating speed of said pump means and thereafter releasing said overriding control after a water hammering phenomena caused by said abrupt change in the operation state of another pump means has settled.