MVDC Collection System With DC/DC Step-Up Converters
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current offshore wind power plants face inefficiencies in medium voltage AC collection systems due to high power losses in transformers and AC cables, and existing MVDC solutions struggle to achieve high voltage ranges without DC/DC conversion at wind turbines, necessitating a more efficient and reliable medium voltage DC collection system for large offshore wind farms.
Innovation Solution
A multi-phase wind turbine generator system with power cell based modular converters and medium frequency or high frequency transformers is employed to create a medium voltage DC collection system, utilizing DC/DC step-up converters to achieve high voltage DC outputs up to 50 kV, reducing the need for wind turbine transformers and improving power density and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If medium voltage AC collection systems are used, then existing technology is available and easy to implement, but power losses in transformers and AC cables increase, reducing system efficiency
Solution Approach 1:
The patent replaces the traditional AC collection system with a DC collection system, substituting the mechanical/electromagnetic transformation process (AC-AC transmission) with a direct DC transmission approach. This eliminates the need for AC transformers and reduces power losses associated with AC cable transmission, directly addressing the energy loss problem while managing complexity through standardized DC equipment design.
Solution Approach 2:
The patent changes the fundamental electrical parameter from AC to DC, operating the collection system at DC voltages between 1 kV and 50 kV. This parameter change eliminates the need for AC-specific equipment like transformers and enables more efficient power transmission by reducing resistive losses and eliminating reactive power issues inherent in AC systems.
2Loss of energy
If collection system voltage is increased from 33 kV to 72 kV, then system efficiency improves, but the dimension of electrical equipment inside the wind turbine tower increases
Solution Approach 1:
The patent eliminates the need for step-up transformers by implementing DC generation directly at the turbine level or using DC-DC conversion. This substitution removes the bulky transformer equipment from the turbine tower, solving the space constraint problem while enabling higher voltage operation for improved efficiency in the collection system.
Solution Approach 2:
The patent segments the power conversion function into modular DC-DC converters that can be distributed across multiple locations in the collection system rather than requiring a single large transformer at each turbine. This segmentation allows for more flexible space utilization and reduces the volume of equipment at any single location while maintaining high voltage efficiency.
3Reliability
If DC/DC power conversion is implemented at wind turbines to achieve high voltage DC output, then power density and reliability improve, but the complexity of power electronics increases
Solution Approach 1:
The patent employs DC-DC power conversion with controlled voltage multiplication to achieve high voltage DC output (1 kV to 50 kV) at the turbine level. This parameter transformation enables direct connection to the MVDC collection system without AC conversion, improving reliability by eliminating AC-DC conversion stages and reducing overall system complexity despite the use of power electronics.
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 enhances the efficiency and reliability of offshore wind power transmission by minimizing power losses and insulation stress, enabling cost-effective and high-performance medium voltage DC collection systems for large offshore wind farms, improving overall system efficiency and controllability.
Implementation Method 1
multi-phase wind turbine generator and power cell based modular converters with middle frequency or high frequency transformers
Implementation Method 2
power cell based modular converters with middle frequency or high frequency transformers to enable medium voltage direct current electrical systems
Data Source
AI summary
A power generation system includes at least one generator that generates a medium voltage direct current that has a positive DC voltage output and a negative DC voltage output. The system also provides a medium voltage DC (MVDC) cable system with a positive pole cable and a negative pole cable, wherein the positive pole cable is connected to the positive DC voltage output and the negative pole cable is connected to the negative DC voltage output. A substation is connected to the MVDC cable system and includes at least one DC/DC step-up converter to step-up the medium voltage direct current to a high voltage direct current.