Subsea Power Supply Assembly with Variable Frequency UPS
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Solution Overview
Problem
Existing subsea power supply systems face challenges in providing power to subsea UPS units due to the Ferranti effect in long step-outs, leading to stability issues and increased costs with additional cables, and crosstalk problems when trying to integrate UPS power with motor power in the same umbilical.
Innovation Solution
A subsea power supply assembly that uses a variable speed drive connected to a step-up transformer, with a step-out cable transmitting power to a subsea location where a step-down transformer and uninterruptable power supply (UPS) receive variable frequency power, allowing the UPS to operate within a wide frequency range matching the motor's speed, and sharing the same conductors as the electric motor, thereby reducing the need for additional cables and minimizing crosstalk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional conductors are arranged in the umbilical to supply power to subsea UPS units, then the UPS can receive dedicated power supply, but the umbilical outer diameter becomes excessive and cost increases dramatically
Solution Approach 1:
The patent makes the motor power conductors serve dual purposes: supplying power to both the electric motor and the subsea UPS unit. The same three-phase conductors that deliver motor power are also used to deliver control power to the UPS, eliminating the need for separate dedicated control power conductors and reducing umbilical complexity
Solution Approach 2:
The patent combines the motor power supply function and the UPS power supply function into a single integrated power delivery system. By merging these two functions into one set of conductors, the umbilical structure is simplified, reducing its outer diameter and manufacturing cost while maintaining reliable power supply to both loads
2Length of stationary object
If conductors are arranged in the same layer in the umbilical to save space, then the umbilical diameter is reduced, but crosstalk occurs between power supply systems
Solution Approach 1:
The patent acknowledges that placing conductors in the same layer creates crosstalk, but converts this potential harm into a benefit by using the controlled crosstalk as a coupling mechanism. The motor power conductors intentionally induce voltages in the UPS power conductors through electromagnetic coupling, allowing power transfer without requiring physical isolation or separate layers
Solution Approach 2:
The patent introduces electromagnetic induction as an intermediary mechanism for power transfer. Instead of directly connecting UPS conductors to the power source through separate cables, the system uses the magnetic field generated by motor power conductors as an intermediary to induce and transfer power to the UPS conductors, enabling wireless-like coupling within the same cable layer
3Reliability
If a dedicated umbilical is used for subsea UPS power supply, then power reliability is ensured, but the cost and complexity of the system increases dramatically
Solution Approach 1:
The patent makes the motor power conductors serve dual purposes: supplying power to both the electric motor and the subsea UPS unit. The same three-phase conductors that deliver motor power are also used to deliver control power to the UPS, eliminating the need for separate dedicated control power conductors and reducing umbilical complexity
Solution Approach 2:
The patent combines the motor power supply function and the UPS power supply function into a single integrated power delivery system. By merging these two functions into one set of conductors, the umbilical structure is simplified, reducing its outer diameter and manufacturing cost while maintaining reliable power supply to both loads
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
This solution enables efficient and cost-effective power supply to subsea UPS units with reduced cable requirements and eliminates crosstalk, ensuring stable operation of subsea control systems by matching the UPS input frequency with the motor's frequency, thus supporting safe shutdown and operation of subsea control systems.
Implementation Method 1
a step-up transformer connected to the variable speed drive output
Implementation Method 2
a first step-down transformer having an input and an output... The step-out cable is connected to the first step-down transformer
Implementation Method 3
A subsea power supply assembly supplying electric power to an electric motor at a second location from a first location. At the first location, the assembly comprises a variable speed drive having a variable speed drive output
Data Source
AI summary
Subsea power supply assembly supplying electric power to a motor at a second location from a first location. The subseas power supply assembly includes a variable speed drive (VSD) and a step-up transformer connected to it. At a subsea location the assembly includes a first step-down transformer with input and output and an uninterruptible power supply having an input. A step-out cable supplies power from the step-up transformer to the motor. The cable connects to the first step-down transformer. The speed of the electric motor is proportional to the output frequency of the VSD. The power receiving input of the uninterruptible power supply connects to the output of the first stepdown transformer, thereby receiving electrical power with frequency equal to the output frequency of the VSD.