HVDC Transmission Voltage Control for Line Longevity
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Solution Overview
Problem
Existing power transmission systems face challenges in increasing transmission line longevity, reducing working stress, lowering operating costs, and minimizing power losses, particularly when converting AC to DC power lines, which are subject to high stress and inefficiencies.
Innovation Solution
A power transmission system that includes a transformer and power converters with modular multilevel converter topology, capable of converting AC to DC and back to AC, with a control system that dynamically adjusts DC voltage based on demand, using pulse width modulation and sensor data to optimize voltage levels and reduce stress on transmission lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If DC power line constantly transmits power at high voltage, then power transmission capability is improved, but transmission line longevity deteriorates due to high working stress
Solution Approach 1:
The patent implements dynamic voltage control in the DC power transmission system, where the voltage level is adjusted in real-time based on power demand conditions. During peak demand periods, high voltage is maintained to maximize power transmission capability. During low demand periods, voltage is reduced to minimize working stress on transmission lines and extend their service life. This dynamic adjustment mechanism resolves the contradiction between maintaining high power transmission capability and preserving transmission line longevity.
2Power
If AC to DC conversion is implemented, then power line capability is improved, but system complexity increases
Solution Approach 1:
The patent extracts and addresses only the essential conversion functions needed for AC to DC transformation, implementing a streamlined conversion system that maintains power line capability while avoiding unnecessary complexity. The conversion system is integrated directly into the existing power transmission infrastructure, removing separate complex conversion stations and reducing overall system complexity while preserving the enhanced power transmission benefits.
3Productivity
If high voltage DC transmission is used, then power transmission efficiency is improved, but power losses increase due to high working stress
Solution Approach 1:
The patent implements periodic voltage adjustment cycles that alternate between high voltage operation during peak demand (maximizing transmission efficiency) and reduced voltage operation during low demand (minimizing power losses and working stress). This periodic action pattern allows the system to optimize for efficiency when needed while reducing energy losses and stress on transmission components during other periods, resolving the contradiction between transmission efficiency and power loss reduction.
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
The system extends transmission line longevity, reduces operating costs, and minimizes power losses by dynamically adjusting DC voltage in response to demand, thereby managing stress and improving efficiency.
Implementation Method 1
with a control system that dynamically adjusts DC voltage based on demand, using pulse width modulation and sensor data to optimize voltage levels
Data Source
AI summary
Unique systems, methods, techniques and apparatuses of power transmission systems are disclosed herein. One exemplary embodiment is an AC power transmission system converted for transmission of high voltage direct current (HVDC) power, the converted system comprising an AC cable system, a first converter system, a second converter system, and a control system. The first converter system is structured to receive and convert AC power to DC power and output the DC power. The second power converter system is structured to receive the DC power, convert the DC power to a second AC power, and output the second AC power. The control system is structured to receive power demand information, determine a reduced DC voltage less than a rated HVDC voltage, control the first converter system such that the DC power is controlled to the reduced voltage, and control the second power converter system to operate in an active power control mode.