Pump Jack Motor Voltage Control for Energy Waste Reduction
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Solution Overview
Problem
Pump jack electric motors inefficiently generate energy, leading to unnecessary energy consumption and waste, particularly due to imperfect well balance caused by varying fluid compositions, improper setup, and other factors, resulting in excessive energy being returned to the grid.
Innovation Solution
A closed-loop motor controller system that reduces supply voltage during energy generation mode and uses pulse width modulation to minimize real power consumption, allowing reactive current flow for feedback and adjusting voltage based on motor load, thereby reducing energy waste and braking action from the utility grid.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the electric motor operates in energy generation mode due to imperfect well balance, then kinetic energy is returned to the grid, but excessive energy consumption and waste occur
Solution Approach 1:
The system continuously monitors the phase angle between voltage and current to detect energy generation mode (phase angle > 90 degrees). This feedback mechanism enables the controller to identify when the motor is generating energy and automatically adjust the supply voltage to minimize energy waste while maintaining pumping operation.
Solution Approach 2:
The motor controller dynamically adjusts the supply voltage based on real-time operating conditions. By modulating the voltage during energy generation mode, the system adapts to changing well conditions and fluid compositions, optimizing energy consumption and preventing excessive energy return to the grid.
2Loss of energy
If the supply voltage is reduced during energy generation mode, then energy waste is minimized, but the motor may not have sufficient power during high load conditions
Solution Approach 1:
The system applies pulse width modulation (PWM) to deliver periodic voltage pulses to the motor. During energy generation mode, the controller reduces voltage during specific phases of the pumping cycle when power demand is lower, while maintaining sufficient voltage during high-load periods. This periodic action optimizes energy waste reduction without compromising overall motor power availability.
3Ease of operation
If the system adapts to changing well conditions automatically, then special setup procedures are eliminated, but the control system complexity increases
Solution Approach 1:
The motor controller performs self-adjustment by continuously monitoring phase angle and automatically modulating supply voltage in response to changing well conditions. The system eliminates the need for manual setup procedures and expert intervention, as it autonomously adapts to varying fluid compositions, well balance conditions, and pumping requirements through real-time feedback control.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system achieves significant energy savings by minimizing energy generation and utilization of natural kinetic energy for pumping, adapting to changing well conditions without requiring special setup procedures.
Implementation Method 1
The pump jack is often powered by an electric motor that receives electrical power from an electric utility grid
Implementation Method 2
The counterweight assists the motor in lifting the string of sucker rods or tubular string. When the motor lifts the counterweight upward, the horse head moves downward, pushing the sucker rods or tubular string downward. After the counterweight reaches the top of its rotation, it swings around and assists the electric motor to rotate the walking beam in the opposite direction using the counterweight's momentum and mass (kinetic energy).
Implementation Method 3
The pump jack converts the rotary mechanism of the electric motor to a vertical reciprocating motion to drive the downhole pump
Data Source
AI summary
A system and method are provided for reducing the energy consumed by a pump jack electric motor by reducing the supply voltage to the motor when the motor would be generating energy in open loop mode. By substantially eliminating the energy generation mode, the braking action of the utility grid in limiting the acceleration of the motor and system that would otherwise occur is substantially removed. The motor and system will speed up, allowing the natural kinetic energy of the cyclic motion to perform part of the pumping action. In particular, when the energy consumption for the electric motor connected with the device having a rotating or reciprocating mass goes to zero, the line voltage to the motor is switched off, causing the frequency of the voltage across the motor terminals to increase. When the period of the voltage across the motor terminals returns to substantially the same as the period of the line voltage, the line voltage is switched on or reapplied to the motor.