ESP Permanent Magnet Motor Backspin Detection by Phase Angle
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Solution Overview
Problem
The detection of backspin in permanent magnet motors used in electric submersible pumps (ESPs) is challenging due to the motor's capability to spin at high speeds in both directions, making voltage magnitude alone insufficient for determining spin direction, and poses risks of equipment damage and safety hazards.
Innovation Solution
A system utilizing sensors to measure electrical characteristics such as voltage, current, and phase angles, combined with algorithms to analyze these parameters, to accurately detect backspin in permanent magnet motors, providing real-time alerts and safety measures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If voltage magnitude is used to detect backspin in permanent magnet motors, then the detection method is simple, but the detection accuracy is insufficient because voltage magnitude alone cannot determine spin direction
Solution Approach 1:
The patent transitions from one-dimensional voltage magnitude measurement to two-dimensional phase angle analysis. By measuring the phase angles between different motor windings and comparing their relationships, the system can determine spin direction accurately. This dimensional expansion allows the simple voltage measurement approach to be enhanced with phase angle information, resolving the contradiction between simplicity and accuracy.
Solution Approach 2:
The patent changes the detection parameter from voltage magnitude alone to a combination of voltage magnitude and phase angle relationships. By monitoring how phase angles change during motor operation and comparing them against reference values, the system can distinguish between forward rotation and backspin conditions. This parameter transformation enables accurate backspin detection while maintaining practical implementation simplicity.
2Power
If permanent magnet motors are used in ESPs, then the motor efficiency and power density are improved, but the risk of equipment damage and safety hazards increases due to pronounced backspin effects
Solution Approach 1:
The patent implements a feedback mechanism that continuously monitors motor electrical characteristics and compares them against expected operating patterns. When backspin conditions are detected through phase angle analysis, the system generates alerts and can trigger protective actions. This closed-loop feedback approach allows the high-performance permanent magnet motors to operate safely by detecting and responding to abnormal backspin conditions in real-time.
Solution Approach 2:
The patent applies preliminary protective measures by detecting backspin conditions before they can cause equipment damage. The phase angle monitoring system identifies reverse rotation early in the backspin process, allowing the control system to take preventive actions such as shutting down the motor or activating braking mechanisms. This preliminary anti-action prevents the harmful effects of prolonged backspin while maintaining the benefits of using permanent magnet motors.
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
Enables precise detection of backspin in permanent magnet motors, preventing equipment damage and ensuring safe operation by identifying spin direction and initiating appropriate safety protocols.
Implementation Method 1
a sensor disposed at a location remote from the electric motor and configured to measure voltage, current, and phase angle signals on power input connections of the electric motor
Implementation Method 2
As the column of fluid drains back down toward the reservoir, through the ESP, the pump and motor are driven backward (in the opposite direction to powered operation), inducing a generated voltage up the cable
Data Source
AI summary
Electric motors are used in oil and gas applications to drive downhole submersible pumps. Upon shutdown of such pumps, a column of fluid remains thereabove. When power is removed, the fluid flows back down the casing causing the motor to rotate backward and generate a voltage that is applied up the power cable to the surface. If the motor is restarted before backspin ceases, damage to the drive shaft is likely. Additionally, the up-hole applied voltage during backspin can pose a shock-risk to personnel at the surface. The present systems and methods minimize these risks by identifying backspin events based on determining phase angle differences at the three phases of the permanent magnet motors and alerting relevant personnel and otherwise preventing re-initiation of motor operation until after backspin has ceased.