METHOD TO SAVE ENERGY FOR DEVICES WITH ROTATING OR RECIPROCATING MASSES
First Claim
1. A method of saving energy for a pump jack with a counterweight disposed with a well, comprising the steps of:
- connecting a closed loop motor controller to an electric motor connected with the pump jack, wherein said motor controller having switching devices;
supplying a line voltage and current to said motor;
rotating the pump jack counterweight with said motor for a plurality of pumping cycles;
observing the phase angle between the voltage and current supplied to said motor with said motor controller;
comparing the observed phase angle with a threshold phase angle;
adjusting the supply voltage upon reaching said threshold phase angle using a firing angle of said switching devices to maintain the observed phase angle at a value no greater than a target phase angle;
reinstating the full supply voltage to said motor when the firing angle falls below a threshold firing angle;
identifying the time periods during the pumping cycles that the supply voltage is adjusted;
comparing said time periods to establish predetermined turn-off time periods for switching off the supply voltage;
after the step of comparing, switching off the supply voltage to the motor during said predetermined turn-off time periods; and
switching on the supply voltage during the other times periods, wherein the other time periods being predetermined turn-on time periods.
1 Assignment
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Accused Products
Abstract
A system and method are disclosed for turning off the voltage to a pump jack electric motor during predetermined periods of time to save energy. In the method, the motor'"'"'s response to closed-loop control may be evaluated over several pump strokes. The periods of the pump stroke when it is feasible to turn off the motor may be identified. The consistency of the measurements over several strokes may be evaluated. The motor may be turned off during predetermined periods on subsequent pump strokes when each pump stroke shows sufficiently similar behavior to that predicted during the closed-loop control process. The system may return to the closed-loop control process after a predetermined period of time to adjust to any changes in the system.
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Citations
20 Claims
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1. A method of saving energy for a pump jack with a counterweight disposed with a well, comprising the steps of:
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connecting a closed loop motor controller to an electric motor connected with the pump jack, wherein said motor controller having switching devices; supplying a line voltage and current to said motor; rotating the pump jack counterweight with said motor for a plurality of pumping cycles; observing the phase angle between the voltage and current supplied to said motor with said motor controller; comparing the observed phase angle with a threshold phase angle; adjusting the supply voltage upon reaching said threshold phase angle using a firing angle of said switching devices to maintain the observed phase angle at a value no greater than a target phase angle; reinstating the full supply voltage to said motor when the firing angle falls below a threshold firing angle; identifying the time periods during the pumping cycles that the supply voltage is adjusted; comparing said time periods to establish predetermined turn-off time periods for switching off the supply voltage; after the step of comparing, switching off the supply voltage to the motor during said predetermined turn-off time periods; and switching on the supply voltage during the other times periods, wherein the other time periods being predetermined turn-on time periods. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method of saving energy for a pump jack with a counterweight disposed with a well, comprising the steps of:
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supplying a line voltage and current to an electric motor connected with the pump jack, wherein the current having a real component and a reactive component; rotating the pump jack counterweight with said electric motor for a plurality of pumping cycles; observing the phase angle between the voltage and current supplied to said motor with a motor controller electrically connected with said motor; comparing the observed phase angle with a threshold phase angle; controlling the supply voltage to said motor upon reaching said threshold phase angle to maintain the observed phase angle at a target phase angle and causing the current real component to be substantially zero and the current reactive component to be greater than zero; reinstating the full supply voltage to said motor when there is an increase in a load on said motor; identifying the time periods during the pumping cycles that the supply voltage is controlled; setting predetermined turn-off time periods for turning off the supply voltage from said identified time periods; and switching off the supply voltage to said motor during said predetermined turn-off time periods and switching on the supply voltage during the other times. - View Dependent Claims (15, 16, 17)
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18. A method of saving energy for a pump jack with a counterweight disposed with a well, comprising the steps of:
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supplying a line voltage and current to an electric motor connected with the pump jack, wherein the current having a real component and a reactive component; rotating the pump jack counterweight with said electric motor for a plurality of pumping cycles; observing the phase angle between the voltage and current supplied to said motor with a closed-loop PID motor controller in electrical connection with said motor; comparing the observed phase angle with a threshold phase angle with said motor controller; adjusting the supply voltage upon reaching said threshold phase angle to maintain the observed phase angle at a value no greater than a target phase angle; reinstating the supply voltage to said motor when a firing angle of said motor falls below a threshold firing angle; identifying the time periods during the pumping cycles occurring between the threshold phase angle and the threshold firing angle; comparing said time periods to establish predetermined turn-off time periods for switching off the supply voltage; switching off the supply voltage to said motor during said predetermined turn-off time periods and switching on the supply voltage during the other time periods, wherein said other time periods being predetermined turn-on time periods; observing a turn-on phase angle immediately after beginning the predetermined turn-on time periods; comparing said turn-on phase angle with an ideal phase angle; increasing said predetermined turn-off time periods if the turn-on phase angle is greater than the ideal phase angle, and decreasing said predetermined turn-off time periods if the turn-on phase angle is less than the ideal phase angle; and after the steps of switching off and switching on, repeating the steps of supplying, adjusting, reinstating, and comparing. - View Dependent Claims (19, 20)
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Specification