Managing regenerative energy of reciprocating pumping unit

Patent metadata

Field	Value
Publication number	US-2026098459-A1
Application number	US-202418907485-A
Country	US
Kind code	A1
Filing date	Oct 5, 2024
Priority date	Oct 4, 2024
Publication date	Apr 9, 2026
Grant date	—

Abstract

A variable frequency drive to drive an electric motor for a reciprocating pumping unit includes a rectifier, a filter, an inverter, and a capacitor bank. The rectifier converts AC power to DC power for filtering by the filter. The inverter converts the DC power to three-phase AC power for output to the electric motor. The capacitor bank has one or more capacitors connected to the DC bus. The capacitor bank can store regenerative power passed from the motor through the inverter and can supply the stored DC power to the DC bus to drive the electric motor. Control circuitry can control the speed of the electric motor provided by the variable frequency drive during strokes of the pumping unit. The control circuitry can pre-charge the capacitor bank from AC power. The control circuitry can detect any fault condition.

First claim

1 . A method of operating a pumping unit having an electric motor to reciprocate a downhole pump with a rod string, the method comprising:
stroking the pumping unit in strokes by driving the electric motor with a variable frequency drive; measuring operational parameters of the pumping unit using sensors associated with the pumping unit; determining, based on the operational parameters, at least one straightway speed and at least one cornering speed for the strokes of the pumping unit; controlling the variable frequency drive to drive the electric motor by:
decelerating the strokes of the pumping unit in a deceleration from the at least one straightway speed toward the at least one cornering speed, and
accelerating the strokes of the pumping unit in an acceleration from the at least one cornering speed toward the at least one straightway speed;
storing regenerative power in a capacitor bank in electrical connection to the variable frequency drive, the regenerative power being produced during the deceleration; and supplying stored power from the capacitor bank to the variable frequency drive to at least partially drive the electric motor during the acceleration.

2 . The method of claim 1 , wherein measuring the operational parameters of the pumping unit using the sensors associated with the pumping unit comprises sensing values of a surface load associated with the pumping unit, a speed associated with the electric motor, and a position associated with the pumping unit.

3 . The method of claim 1 , wherein determining, based on the operational parameters, the at least one straightway speed and the at least one cornering speed for the strokes of the pumping unit comprises:
calculating, based on the operational parameters, downhole position and downhole load associated with the downhole pump; and determining the at least one straightway speed and the at least one cornering speed based on the downhole position and the downhole load determined.

4 . The method of claim 1 , comprising:
determining at least one turnaround deceleration rate in the deceleration from the at least one straightway speed to the at least one cornering speed; and determining at least one turnaround acceleration rate in the acceleration from the at least one cornering speed to the at least one straightway speed.

5 . The method of claim 1 , wherein controlling, storing, and supplying comprises:
(i) accelerating the strokes of the pumping unit in a first transition from a first of the at least one cornering speed toward a first of the at least one straightway speed, and supplying stored power during the acceleration for the first transition; (ii) decelerating the strokes of the pumping unit in a second transition from the first straightway speed toward a second of the at least one cornering speed, and storing regenerative power during the deceleration for the second transition; (iii) accelerating the strokes of the pumping unit in a third transition from the second cornering speed toward a second of the at least one straightway speed, and supplying stored power during the acceleration for the third transition; and (iv) decelerating the strokes of the pumping unit in a fourth transition from the second straightway speed toward the first cornering speed, and storing regenerative power during the deceleration for the fourth transition.

6 . The method of claim 1 , wherein driving the electric motor with the variable frequency drive comprises:
converting, in a rectifier stage of the variable frequency drive, input of alternating current (AC) power from an AC power source to direct current (DC) power for a DC bus of the variable frequency drive; and converting, in an inverter stage of the variable frequency drive, the DC power to three-phase AC power for output to the electric motor.

7 . The method of claim 6 ,
wherein storing the regenerative power in the capacitor bank connected to the variable frequency drive comprises storing, in the capacitor bank, the regenerative power passed from the electric motor back through the inverter stage to the DC bus; and wherein discharging the stored power from the capacitor bank to the variable frequency drive to at least partially drive the electric motor comprises converting, in the inverter stage, the DC power on the DC bus drawn from the rectifier stage and the capacitor bank to three-phase AC power for output to the electric motor.

8 . The method of claim 6 , further comprising pre-charging the capacitor bank of the variable frequency drive by:
disconnecting the capacitor bank from the DC bus of the variable frequency drive and connecting a pre-charging circuit to the AC power source; converting, with the pre-charging circuit, the AC power from the AC power source to the DC power at a target voltage level for the capacitor bank; and disconnecting the pre-charging circuit from the AC power source and connecting the capacitor bank to the DC bus after pre-charging the capacitor bank to the target voltage level.

9 . The method of claim 6 , wherein driving the electric motor comprises:
measuring one or more of a voltage level, a current level, and a temperature level associated with at least one of the DC bus of the variable frequency drive and the capacitor bank; and detecting, based on the measurement, one or more of a voltage fault, a current fault, and a temperature fault.

10 - 20 . (canceled)

Assignees

• Weatherford Tech Holdings Llc

Inventors

• Thomas Benson
• Arefeen Mohammed S

Classifications

• F04B47/022

  driving of the walking beam · CPC title

• F04B49/06

  Control using electricity (regulating by means of floats actuating electric switches F04B49/04) · CPC title

• H02P27/04

  using variable-frequency supply voltage, e.g. inverter or converter supply voltage · CPC title

• F04B47/02

  the driving mechanisms being situated at ground level (F04B47/12 takes precedence) · CPC title

• F04B49/20

  by changing the driving speed · CPC title