Energy efficient sewage pumping system with a controller and variable frequency drive and method

摘要

A system includes a pump that is operative to move liquid out of a reservoir. The system also includes a depth level sensor that is operative to determine a depth level of the liquid in the reservoir, and a controller operatively connected to the depth level sensor. The system further includes a variable frequency drive operatively connected to the motor and the controller. Responsive to the determined depth level of the liquid increasing to a first level, the controller is operative to start operation of the motor. The variable frequency drive is operative to control the speed of the motor. The controller is operative to cause the variable frequency drive to output an optimum frequency that causes the motor to operate at substantially the lowest usage of energy to lower the depth level of the liquid in the reservoir from the first level to a second level.

主权项

1. A system comprising:
a pump, wherein the pump includes a motor, wherein the pump is operative to move liquid out of a reservoir; a depth level sensor, wherein the depth level sensor is operative to determine a depth level of the liquid in the reservoir; at least one controller, wherein the at least one controller is operatively connected to the depth level sensor; a variable frequency motor drive operatively connected to the motor and the controller, wherein the variable frequency motor drive is operative to control speed of the motor; and wherein responsive to the determined depth level of the liquid increasing to at least a first level, the at least one controller is operative to start operation of the motor, determine an optimal frequency outputted by the variable frequency motor drive that will cause the motor to operate with lowest energy usage to lower the depth level of the liquid in the reservoir from the first level to a lower second level, cause the variable frequency motor drive to output the optimal frequency to the motor to operate the motor with lowest energy usage, wherein the at least one controller is operative to determine the energy used by the motor during the operation of the pump in moving liquid out of the reservoir from the first level to the second level by subtracting the power consumption of the motor of the pump at the first level from the power consumption of the motor of the pump at the second level, wherein the at least one controller is operative to cause the variable frequency motor drive to output a lower frequency for each successive pump operation until the energy used by the motor for the last pump operation is greater than or equal to the energy used by the motor for the previous pump operation, wherein the at least one controller is operative to determine that the optimal frequency is the frequency outputted by the variable frequency motor drive for the last pump operation in which the energy used by the motor is greater than or equal to the energy used by the motor for the previous pump operation.