Superconducting DC Power Transmission System for Offshore Wind Farms
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Solution Overview
Problem
Conventional AC transmission systems face inefficiencies and high costs due to capacitance issues, especially in long-distance power transmission from remote power generation sites like offshore wind farms, and high voltage DC systems require complex and expensive equipment for efficient power transmission.
Innovation Solution
A power transmission system utilizing a superconducting DC cable with a current-controlled topology, where power collection systems are coupled in series with a superconducting DC conductor to maintain a substantially constant current, reducing the need for expensive switchgear and simplifying the collector system, and using medium voltage DC transmission to facilitate efficient power delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If conventional HVAC transmission is used for long-distance power transmission, then power can be transmitted from remote generation sites, but capacitance causes charging current to flow along the cable length, reducing the source carrying capability and increasing cable costs
Solution Approach 1:
The patent changes the fundamental transmission parameter from alternating current to direct current, eliminating the capacitive charging current problem that limits AC cable carrying capability over long distances. This parameter change allows the cable to transmit only the useful source current without additional capacitive losses.
Solution Approach 2:
The patent replaces conventional HVAC transmission infrastructure with a superconducting DC transmission system, substituting the mechanical/electrical AC system with a superconducting DC system that has fundamentally different electrical characteristics and no capacitive effects.
2Loss of energy
If high voltage DC transmission is used to transmit high power efficiently, then transmission losses are reduced, but complex and expensive equipment such as switchgear and circuit breakers is required to handle high short circuit current
Solution Approach 1:
The patent changes the current control parameter from voltage-controlled to current-controlled operation. This fundamental parameter change transforms the system behavior so that current is maintained constant while voltage adjusts, eliminating the high short circuit current problem that requires complex switchgear in conventional HVDC systems.
Solution Approach 2:
The patent replaces expensive, complex HVDC switchgear and circuit breakers with simple semiconductor switching devices in the power electronic converters. These simpler, more reliable components perform the necessary isolation and protection functions without requiring costly high-voltage DC switching equipment.
3Power
If voltage controlled DC transmission system is used, then power transmission can be achieved, but the current may rapidly increase during faults and expensive switchgear is needed to perform interrupt functions
Solution Approach 1:
The patent implements current control with feedback mechanisms in the power electronic converters that actively regulate current levels. During fault conditions, the feedback control rapidly detects current deviations and adjusts the converter output to maintain constant current, preventing the rapid current increase that plagues voltage-controlled DC systems.
Solution Approach 2:
The patent incorporates protection mechanisms within the power electronic converters that anticipate and prevent fault conditions. The current-controlled topology inherently limits current excursions before they can become dangerous, and the semiconductor switches provide built-in protection against overcurrent conditions without requiring external switchgear.
4Device complexity
If medium voltage DC transmission with current-controlled topology is used, then equipment complexity and cost are reduced, but the system must maintain substantially constant current which requires precise control
Solution Approach 1:
The patent replaces mechanical current control mechanisms with electronic control through power electronic converters. These converters use semiconductor devices and electronic control circuits to precisely regulate current levels, providing the necessary automation and precision without mechanical complexity.
Solution Approach 2:
The power electronic converters perform multiple functions simultaneously: they convert AC to DC, control current levels, provide fault protection, and enable medium voltage transmission. This multi-functionality eliminates the need for separate current control equipment, switchgear, and protection devices, simplifying the overall system.
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 approach enables economical and efficient transmission of high power, such as 200 MW, at a medium voltage level, reducing the complexity and cost of equipment, and minimizing transmission losses, while avoiding the need for circuit breakers and transformers, thus enhancing the overall efficiency and reliability of power transmission.
Implementation Method 1
a first plurality of power collection systems coupled in series with at least one superconducting DC conductor to form a first transmission circuit for transmission of power to a remote location
Data Source
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AI summary
A direct current (DC) power transmission system (10) is described. The DC power transmission system includes a first plurality of series connected power collection systems (12) and at least one superconducting DC conductor (32) coupled to the plurality of series connected power collection systems and configured to transmit power generated by the plurality of power collection systems to a remote load (42).