HVDC Transformer Topology for Long-Distance Renewable Grid Links
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Solution Overview
Problem
Current power transmission systems using long-distance AC cables for connecting new energy power generation to the electric grid face inefficiencies and high costs, particularly in scenarios like offshore wind farms where distances are vast.
Innovation Solution
A high-voltage DC transformation apparatus is introduced, comprising bidirectional AC/DC conversion modules, transformers, and unidirectional rectifier modules, which convert DC power to AC, boost it, and then rectify it back to DC, enabling efficient long-distance transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If long-distance AC cable transmission is used to connect power systems to the electric grid, then the power transmission distance is extended, but the transmission efficiency decreases and costs increase
Solution Approach 1:
The patent transforms the power transmission system from AC to DC mode and implements high-voltage boosting. Specifically, the bidirectional AC/DC conversion module converts AC power to DC power, the DC voltage boosting module increases the DC voltage level, and the unidirectional rectifier module converts the boosted DC power back to AC for grid connection. This parameter transformation enables efficient long-distance transmission by reducing resistive losses associated with AC transmission over vast distances.
2Length of moving object
If long-distance AC cable transmission is used to connect power systems to the electric grid, then the power transmission distance is extended, but the transmission cost increases
Solution Approach 1:
The patent implements high-voltage DC transmission through parameter transformation. The DC voltage boosting module increases the voltage level, which reduces current for the same power transmission. Since transmission losses are proportional to the square of the current, this voltage increase dramatically reduces energy losses and associated costs for long-distance transmission of new energy power.
3Loss of energy
If DC power is converted to AC, boosted, and then rectified back to DC for transmission, then transmission efficiency is improved, but device complexity increases
Solution Approach 1:
The patent divides the power transformation system into three functional modules: the bidirectional AC/DC conversion module, the DC voltage boosting module, and the unidirectional rectifier module. Each module performs a specific function in the power transformation chain, making the overall complex system manageable through functional segmentation and modular design.
Solution Approach 2:
The bidirectional AC/DC conversion module can operate in both rectification and inversion modes, providing multi-functionality. This module can convert AC to DC during normal operation and DC to AC during grid faults or maintenance, reducing the need for separate backup systems and simplifying the overall apparatus complexity.
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 reduces transmission losses and costs by utilizing high-voltage DC power, and allows for flexible power adjustment through energy storage and auxiliary generators, enhancing grid stability and efficiency.
Implementation Method 1
a first DC voltage is converted into a first AC voltage by a bidirectional AC/DC conversion module
Implementation Method 2
the first AC voltage is boosted to a second AC voltage by a transformer
Implementation Method 3
the second AC voltage is rectified by a unidirectional rectifier module to generate a second DC voltage
Data Source
AI summary
A high-voltage DC transformation apparatus, a power system and a control method of the power system. The high-voltage DC transformation apparatus is electrically connected to at least one high-voltage DC power generator. The high-voltage DC transformation apparatus includes at least one bidirectional AC/DC conversion module, at least one first transformer and at least one unidirectional rectifier module. A DC terminal of the bidirectional AC/DC conversion module is electrically connected to the corresponding high-voltage DC power generator. The first transformer includes a first transmission terminal and a second transmission terminal. The first transmission terminal is electrically connected to an AC terminal of the corresponding bidirectional AC/DC conversion module. The unidirectional rectifier module includes an input terminal and an output terminal. The input terminal is electrically connected to the second transmission terminal of the corresponding first transformer, and the output terminal is electrically connected to a high-voltage grid.