Ground Fault Immune Data Measurement for ESPs
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Solution Overview
Problem
Data measurement systems for downhole electric submersible pumps face limitations in data transfer rate due to electrical impedance of motor windings and power cables, and are unable to transmit data during partial or complete ground faults.
Innovation Solution
A ground fault immune data measurement system that uses frequency modulated carrier signals transmitted via capacitive coupling across motor windings, allowing data to be sent through the 3-phase power cable without being conducted through the motor windings, and includes a method for encoding and multiplexing sensor data for transmission, enabling increased data transfer rates and fault immunity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If data is transmitted through motor windings and power cable, then data can be transmitted from downhole to surface, but data transfer rate is limited by electrical impedance
Solution Approach 1:
The patent introduces an intermediary capacitive coupling mechanism that enables data transmission without direct conduction through the motor windings. The capacitive coupling acts as a mediator that allows high-frequency carrier signals to pass while isolating the transmission path from ground fault conditions, thus resolving both the data transfer rate limitation and reliability issues simultaneously
Solution Approach 2:
The patent replaces the traditional electrical conduction mechanism through motor windings with a capacitive coupling mechanism. This substitution allows data to be transmitted via electromagnetic fields rather than direct electrical conduction, overcoming the impedance limitations and ground fault vulnerabilities of the original system
2Reliability
If data is transmitted through motor windings, then data can be conveyed to surface unit, but system is vulnerable to ground faults
Solution Approach 1:
The capacitive coupling serves as an intermediary element that provides ground fault immunity by isolating the data transmission path from ground potential differences. This intermediary mechanism enables reliable transmission during ground faults without requiring complex protective circuitry or multiple transmission paths
Solution Approach 2:
The patent changes the transmission parameter from electrical conduction through motor windings to capacitive coupling of carrier signals. This parameter change fundamentally alters the transmission characteristics to provide ground fault immunity while maintaining data communication capability
3Productivity
If frequency modulated carrier signals are used for data transmission, then data transfer rate increases, but system complexity increases
Solution Approach 1:
The patent makes the motor windings serve multiple functions: they continue to provide mechanical drive for the pump while simultaneously acting as a capacitive coupling element for data transmission. This multi-functionality enables high-speed data transfer without adding separate transmission infrastructure, thus reducing overall system complexity
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 higher data transfer rates and provides immunity to ground faults, ensuring continuous data transmission even in the presence of partial or complete ground faults, enhancing the reliability of downhole data measurement.
Implementation Method 1
a modulator coupled to the processor and configured to generate a plurality of frequency modulated carrier signals for carrying the sensor data to the surface unit
Implementation Method 2
the downhole unit is capacitively coupled to motor windings of the motor of the ESP and configured to transmit the plurality of carrier signals across the capacitive coupling and to the surface unit via the 3-phase power cable
Data Source
AI summary
Provided are systems and methods for ground fault immune data measurement system for electric submersible pumps. A data measurement system coupled to the ESP includes a surface unit coupled to a 3-phase power cable for providing power to a 3-phase motor of the ESP and a downhole unit coupled to the motor of the ESP and located downhole in a well. The downhole unit includes sensor and is configured to generate frequency modulated carrier signals for carrying the sensor data to the surface unit. Each of the frequency modulated carrier signals carries identical sensor data and is modulated to a different frequency. The carrier signals are shunted across the motor windings of the ESP motor and onto the 3-phase power cable via a capacitive coupling. Additionally, another carrier signal carrying control data may be transmitted from the surface unit to the downhole unit.