Systems and methods for reducing pump downtime by determining rotation speed using a variable speed drive

摘要

Systems and methods for using variable speed drives to restart downhole submersiblepump motors. In one embodiment, a downhole pump is controlled using a variablespeed drive that includes a control system configured to detect interruptionsin the operation of the pump system. After an interruption that requires the restartof the pump motor, the control system determines the reverse rotational speedof the pump motor and restarts the motor when this speed is sufficiently low. Thecontrol system may be configured to reduce the output voltage of the variablespeed drive and sweep through a range of output frequencies to determine the frequencyat which the current drawn by the motor is lowest. This is the frequency at whichthe drive's output matches the speed of the motor and the apparent impedanceof the motor is highest. When the speed is low enough, the motor is restarted.