Backspin Management for Electric Submersible Pump Motors
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Solution Overview
Problem
In oil and gas drilling applications, electric submersible pumps (ESPs) with permanent magnet motors experience backspin, generating voltage on the cable due to relative motion between the magnetic field and stator coils, posing a shock risk to personnel and requiring effective management to prevent hazards.
Innovation Solution
A control system with sensors and a controller detects backspin events by measuring voltage or current on the cable, communicating alerts, controlling voltage to be below a threshold, and restricting access to the cable, utilizing a crowbar circuit or dynamic brake circuit to dissipate energy and mitigate hazards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a permanent magnet motor is used in the ESP, then motor efficiency and power density are improved, but backspin generates voltage on the cable creating shock risk to personnel
Solution Approach 1:
The patent detects backspin-generated voltage and converts this harmful effect into useful information by measuring the voltage magnitude and duration. The system then uses this information to trigger appropriate responses (alerts, access restrictions) that prevent personnel exposure to hazardous voltage levels, effectively turning the harmful backspin phenomenon into a detectable and manageable condition.
Solution Approach 2:
The patent introduces a controller as an intermediary between the permanent magnet motor and the personnel. The controller monitors cable voltage, detects backspin events, and mediates the hazard by implementing control actions (voltage suppression, alerts, access restrictions) that prevent direct exposure of personnel to the harmful voltage generated during backspin.
2Device complexity
If backspin voltage is allowed to exist on the cable, then system simplicity is maintained, but personnel safety is compromised due to shock risk
Solution Approach 1:
The patent implements a feedback mechanism where sensors continuously monitor cable voltage and provide information to the controller. When backspin voltage exceeds predetermined thresholds or persists for predetermined durations, the controller receives feedback and automatically implements control actions. This closed-loop feedback system manages personnel safety without requiring complex manual intervention systems.
Solution Approach 2:
The control system performs self-service by automatically detecting backspin events through voltage monitoring and autonomously implementing control actions (voltage suppression, alerts, access restrictions) without requiring external personnel intervention. The system serves its own safety function through automated detection and response.
3Object-affected harmful factors
If voltage control actions are implemented during backspin, then personnel safety is improved, but system complexity and operational restrictions increase
Solution Approach 1:
The patent implements partial control actions based on the severity and duration of backspin events. Rather than continuously suppressing voltage, the system applies control actions only when voltage exceeds predetermined thresholds or persists for predetermined durations. This selective, partial action approach manages personnel safety while avoiding unnecessary system complexity during normal operation.
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 effectively reduces or eliminates voltage on the cable during backspin events, minimizing shock risks for personnel and ensuring safe operations by actively managing the voltage and access to the cable.
Implementation Method 1
By way of Faraday's law of induction, backspin of the permanent magnet motor may generate a voltage on the cable even when the permanent magnet motor is not actively driven.
Data Source
AI summary
A method of controlling an electric motor assembly includes detecting a backspin event of an electric motor, and managing a response to the detected backspin event of the electric motor. The backspin event of the electric motor is detected based at least in part on feedback from a sensor configured to measure a current or a voltage on a cable coupled to the electric motor. The response includes communicating an alert to personnel, controlling the voltage on the cable to be less than a voltage threshold, or any combination thereof.