HVDC Converter Control via Limb Optimization
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Solution Overview
Problem
Conventional converter control methods fail to independently manage AC and DC current demands and accommodate performance variations in converter limbs, leading to suboptimal operation and increased losses due to equal current contributions from all limbs, regardless of their performance.
Innovation Solution
A method of controlling converters through mathematical optimization, which determines optimal limb portion currents and voltage sources by creating an equivalent converter configuration, applying current and voltage weightings based on measured parameters, and using feedback loops to adjust for performance deviations and environmental factors, allowing for differential contributions from each limb.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional control methods are used to manage converter limbs, then all limb portions are controlled to provide equal current contribution, but this results in increased conduction and switching losses and fails to accommodate performance variations in individual limbs
Solution Approach 1:
The patent applies local quality by determining individual limb portion currents based on the specific performance characteristics of each limb portion. Instead of uniform current distribution, each limb portion is controlled according to its own performance capabilities, thereby reducing overall conduction and switching losses while accommodating local variations in limb performance
Solution Approach 2:
The control method dynamically adjusts limb portion currents based on real-time performance measurements and environmental conditions. The system continuously monitors limb performance and modifies current distribution accordingly, enabling adaptive optimization that reduces losses while responding to changing operating conditions
2Adaptability or versatility
If conventional control methods are used, then AC and DC current demands are managed together, but this prevents independent control of AC and DC current demands
Solution Approach 1:
The patent segments the control of converter limbs into independent AC and DC current demand components. By decomposing the overall current control into separate AC and DC portions, the system enables independent management of each demand type, allowing flexible adaptation to different operating requirements while maintaining overall converter performance
3Reliability
If equal current contributions are enforced from all limb portions, then control is simplified, but this fails to accommodate performance variations and degradation in individual limbs
Solution Approach 1:
The patent implements feedback mechanisms that continuously monitor the performance of each limb portion and use this information to adjust current distribution. This feedback loop enables the system to accommodate performance variations and degradation in individual limbs, maintaining reliable converter operation under degraded conditions while optimizing overall performance
Solution Approach 2:
The control method dynamically changes operating parameters, specifically the current contributions of individual limb portions, based on measured performance characteristics. By adjusting these parameters in response to actual limb performance, the system maintains reliability under degraded conditions while adapting to changing operational requirements
Data Source
AI summary
In the field of high voltage direct current power transmission networks, a method of controlling a converter that includes at least one converter limb which corresponds to a respective phase of the converter, is described. The method includes obtaining a respective AC current demand phase waveform for each converter limb which the corresponding converter limb is required to track, and a DC current demand which each converter limb is also required to track. The method further determining a limb portion current for each limb portion that the limb portion must contribute to track the corresponding required AC current demand phase waveform and the required DC current demand, and providing a limb portion voltage source for each limb portion to achieve the corresponding limb portion current. The method carrying out mathematical optimization to determine one or more optimal limb portion currents and/or provide optimal limb portion voltage sources.