Auxiliary Power Injection on Three-Phase Lines for Remote Subsea Installations
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Solution Overview
Problem
In subsea oil and gas systems, energizing control and monitoring functions prior to the main circuit is challenging due to the need for efficient transmission of auxiliary power over long distances without interfering with the main power supply, especially in systems relying on three-phase electrical power.
Innovation Solution
A system utilizing three long-distance current-carrying conductors with step-up and step-down transformers, along with an auxiliary power supply system that transmits auxiliary electrical power as alternating current or direct current, superimposed on the three-phase power lines, allowing for independent frequency optimization and energization of control electronics and actuators at the remote location.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If auxiliary power is transmitted over long-distance three-phase power lines to remote locations, then control and monitoring functions can be energized prior to main circuit energization, but the auxiliary power transmission may interfere with the main power supply and require additional infrastructure
Solution Approach 1:
The patent combines auxiliary power transmission with the existing three-phase main power lines by injecting auxiliary power at the neutral point. This merging approach allows both main power and auxiliary power to share the same transmission infrastructure, eliminating the need for separate auxiliary power lines and reducing overall system complexity while enabling reliable pre-energization of control functions
Solution Approach 2:
The neutral point of the three-phase system serves as an intermediary connection point for injecting auxiliary power. By using the neutral point as the injection point, the system enables auxiliary power transmission without directly interfering with the three-phase main power supply, as the neutral point provides a common reference that isolates the auxiliary power injection from the phase currents
2Adaptability or versatility
If auxiliary power is transmitted over long distances (e.g., 20+ kilometers), then remote subsea installations can be supported, but energy losses increase significantly
Solution Approach 1:
The patent changes the transmission parameters by using the neutral point injection method, which allows auxiliary power to be transmitted as a common-mode signal. This parameter change enables more efficient long-distance transmission by utilizing the existing cable capacitance and inductance in a favorable configuration, reducing energy losses over distances of 20 kilometers or more while maintaining adaptability to remote subsea installations
3Adaptability or versatility
If auxiliary power is transmitted as zero sequence AC at independent frequency, then control electronics can be optimized for each system, but the transmission system becomes more complex
Solution Approach 1:
The three-phase power lines serve multiple functions: they transmit both the main three-phase power to the remote load and the zero-sequence auxiliary power for control functions. This multi-functionality allows the system to support independent frequency optimization for control electronics while using the same physical infrastructure, reducing overall system complexity despite the frequency conversion requirements
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 reliable and efficient transmission of auxiliary power to remote locations, such as subsea fluid processing stations, facilitating the operation of control systems and actuators before or during main load energization, reducing energy losses and ensuring system functionality and status monitoring.
Implementation Method 1
a step-up transformer at the nearby location configured to increase voltage of the three-phase electrical power for transmission over the three long-distance conductors
Implementation Method 2
a step-down transformer at the remote location configured to decrease voltage of the three-phase electrical power from the three long-distance conductors for use by the main load
Implementation Method 3
an auxiliary power supply system located at the nearby location configured to transmit auxiliary electrical power on the three long-distance conductors
Implementation Method 4
an auxiliary power extraction system located at the remote location configured to extract electrical power that is transmitted on the three long-distance conductors and to energize the auxiliary system with said extracted electrical power
Data Source
AI summary
The present disclosure relates to system and method used to transmit power to a remote location. More specifically, the present disclosure relates to a system and method used to independently energize control and monitoring functions of a remote installation prior to and/or during energizing its main circuit.