Low-Frequency AC Rectification for Long-Distance Offshore Wind Transmission
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current offshore wind farm transmission systems face high costs due to the need for offshore converter stations, which are expensive and complex, especially when transmitting large-capacity wind power over long distances using AC systems, as the capacitive charging current limitations of AC submarine cables restrict direct transmission.
Innovation Solution
Implementing a low-frequency alternating-current uncontrolled rectification electric power transmission system by reducing the rated frequency of the offshore AC system to 8-20 Hz and increasing the length of AC submarine cables, merging offshore and onshore converter stations into a single onshore converter station to avoid the use of offshore platforms and reduce costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If AC systems are used for offshore wind power transmission, then the system structure is simple and technology is mature, but the capacitive charging current limits the transmission distance for large-capacity power
Solution Approach 1:
The patent changes the frequency parameter of the AC system from conventional 50Hz to low frequency (8-20 Hz). This parameter change reduces the capacitive charging current in the submarine cable, enabling long-distance transmission of large-capacity offshore wind power while maintaining the simplicity and technical maturity of AC systems.
2Length of stationary object
If offshore converter stations are used for DC transmission, then long-distance large-capacity transmission is enabled, but the cost and complexity increase significantly
Solution Approach 1:
The patent extracts the converter station from the offshore environment and places it onshore. By using low-frequency AC transmission through extended submarine cables, the system eliminates the need for expensive and complex offshore converter stations, achieving long-distance transmission with simplified onshore-based equipment.
3Length of stationary object
If offshore converter stations are used, then DC transmission capability is achieved, but the project cost increases due to offshore platform requirements
Solution Approach 1:
Instead of the conventional approach of using offshore converter stations for DC transmission, the patent inverts the arrangement by using onshore converter stations with low-frequency AC transmission through submarine cables. This inversion eliminates the need for expensive offshore platforms and associated infrastructure, significantly reducing project costs while maintaining long-distance transmission capability.
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 significantly reduces project costs by eliminating the need for offshore platforms and leveraging the technical maturity of AC transmission solutions, offering a cost-effective and applicable solution for future offshore wind power transmission projects.
Implementation Method 1
due to the limitation of the capacitive charging current of AC submarine cables, long-distance large-capacity wind power cannot be directly sent through the AC systems
Implementation Method 2
offshore wind farm low-frequency alternating-current uncontrolled rectification electric power transmission system
Data Source
AI summary
The present disclosure discloses an offshore wind farm low-frequency alternating-current uncontrolled rectification electric power transmission system, comprising an onshore converter station and an offshore alternating-current system. The offshore alternating-current system comprises wind turbine generators, alternating-current submarine cables, a confluence bus, and offshore booster stations; the onshore converter station comprises a wind field side alternating-current bus, an alternating-current system side alternating-current bus, an alternating-current filter, an energy dissipation device, a rectifier, and a converter; the rectifier is composed of a three-phase six-pulse uncontrolled rectifier bridge, and the converter may be an MMC or an LCC; the rated frequency of the offshore alternating-current system is selected to be close to 10 Hz.