Subsea DC Power Distribution Modules
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Solution Overview
Problem
Subsea oil and gas production systems face challenges with AC transmission and distribution due to significant reactive power drawn from distributed cable capacitance, increasing system cost and requiring complex and costly high-voltage wet-mateable connectors, as well as inaccessibility for maintenance, which disrupts power delivery and increases operational costs.
Innovation Solution
A submersible power system with modular DC power distribution that includes removably positioned power conversion modules and a switchyard module with bypass and isolation switches, allowing for maintenance without disrupting power delivery, using dry-mateable connectors and HVDC cables for lifting and lowering modules, and wet-mateable connectors for underwater connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If AC transmission and distribution systems are used for subsea power delivery, then power can be transmitted to subsea locations, but significant reactive power is drawn from distributed cable capacitance which restrains power delivery capability and increases system cost
Solution Approach 1:
The patent changes the fundamental parameter of power transmission from alternating current (AC) to direct current (DC). This parameter change eliminates the reactive power issue inherent in AC systems, as DC does not exhibit capacitive or inductive reactance. The HVDC transmission system transmits power using direct current through subsea cables, thereby avoiding the reactive power draw from cable capacitance that plagues AC systems and enables more efficient long-distance power delivery to subsea installations.
2Ease of operation
If high-voltage wet-mateable connectors are used for subsea connections, then electrical connections can be made underwater, but the connectors become significantly more expensive and complex
Solution Approach 1:
The patent applies preliminary action by making all electrical connections in a dry environment before submerging the modular components into the water. Modules are assembled, tested, and connected using standard dry-mateable connectors on land or on support vessels, then entire sealed modules are lowered into the subsea environment as complete units. This eliminates the need for complex high-voltage wet-mateable connectors, as no electrical connections are made underwater. The dry connection approach significantly reduces connector complexity and cost while maintaining ease of operation.
3Reliability
If components are enclosed in pressure vessels for subsea protection, then components are protected from the underwater environment, but maintenance requires completely removing the T&D system from service and raising the unitary enclosure
Solution Approach 1:
The patent segments the subsea power distribution system into multiple independent modular units, each housed in its own pressure vessel. These modules can be independently removed, replaced, or maintained without affecting other modules in the system. The segmented modular architecture allows a single module to be serviced while other modules continue to operate, eliminating the need to take the entire T&D system offline for maintenance. This segmentation maintains subsea environment protection through sealed pressure vessels while dramatically improving ease of repair through modular independence.
Solution Approach 2:
The patent enables continuity of useful action by designing the system so that maintenance on one module does not interrupt power delivery from other modules. The modular architecture with independent pressure vessels allows parallel operation of multiple modules, ensuring that the subsea installation continues to receive power during maintenance activities. This continuity eliminates the complete system shutdown required by unitary enclosure designs and maintains productive operation throughout the maintenance process.
4Productivity
If modular power conversion modules are used with removable positioning, then maintenance can be performed without disrupting power delivery, but the system requires complex switchyard modules with bypass and isolation switches
Solution Approach 1:
The patent segments the power distribution system into modular units with integrated switchyard functionality distributed across modules rather than concentrated in a single complex switchyard. Each module contains its own isolation and bypass capabilities, allowing individual modules to be disconnected and maintained without affecting other modules. This distributed segmentation simplifies the overall switchyard complexity by breaking it into smaller, manageable units while maintaining the ability to perform maintenance without disrupting overall power delivery to the subsea installation.
Data Source
AI summary
A submersible power system includes at least one DC power source and at least one submersible power distribution system electrically coupled to the at least one DC power source. The at least one submersible power distribution system includes at least one receptacle configured to be exposed to an underwater environment. The at least one submersible power distribution system also includes a plurality of power conversion modules removably positioned within the at least one receptacle. Each power conversion module of the plurality of power conversion modules includes an enclosure configured to be exposed to the underwater environment. The at least one submersible power distribution system further includes at least one switchyard module selectably coupled to and uncoupled from the plurality of power conversion modules. The at least one switchyard module includes a plurality of switches configured to electrically bypass and isolate each power conversion module from the DC power source.