Self-Excited Converter Control for AC System Vibration Suppression
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Solution Overview
Problem
In systems where self-excited converters and separately-excited converters are connected to the same AC system, changes such as alterations in short-circuit capacity can cause vibrations in the AC system due to control responsiveness issues, potentially leading to hunting and regular vibration patterns.
Innovation Solution
A power conversion device with a control system that detects vibration components in the AC voltage and sets appropriate control parameters for the self-excited converter based on stored vibration information to prevent vibrations. This system includes a vibration detector, a determination unit to find similar vibration information, and a setting unit to adjust the control parameters accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If both self-excited converter and separately-excited converter perform control to prevent vibration in the AC system, then the vibration prevention capability is improved, but hunting of control is generated which causes regular vibration
Solution Approach 1:
The patent introduces a vibration detector as an intermediary component that monitors AC voltage vibration components and provides information to the control device. This mediator enables the control device to make informed decisions about parameter adjustments, preventing direct conflict between the two converters' control actions and eliminating hunting while maintaining vibration prevention capability.
Solution Approach 2:
The patent implements a feedback mechanism where the vibration detector continuously monitors AC voltage vibration components and feeds this information back to the control device. The control device then adjusts control parameters of the self-excited converter based on this feedback, creating a closed-loop control system that prevents vibration without causing hunting.
2Object-affected harmful factors
If the control parameter of the self-excited converter is adjusted to prevent vibration, then the vibration component is reduced, but the control responsiveness may be affected
Solution Approach 1:
The patent dynamically adjusts control parameters of the self-excited converter based on real-time vibration detection. Instead of using fixed parameters, the system changes parameters adaptively in response to detected vibration components, achieving both vibration suppression and maintained responsiveness through dynamic adaptation rather than static configuration.
Solution Approach 2:
The patent changes control parameters of the self-excited converter based on detected vibration conditions. The control device selects from multiple predetermined parameter sets or adjusts parameters continuously based on vibration magnitude and frequency, allowing the system to optimize performance by changing parameters rather than being constrained by fixed settings.
3Power
If the self-excited converter and separately-excited converter are connected to the same AC system to enhance power flow, then the power transmission capability is improved, but vibration is generated due to control responsiveness influence
Solution Approach 1:
The vibration detector serves as an intermediary monitoring system that detects vibration components in the AC system before they escalate. This early detection enables the control device to adjust parameters proactively, allowing both converters to operate together for enhanced power flow while preventing the vibration that would otherwise result from their interaction.
Solution Approach 2:
The patent applies preliminary anti-action by detecting vibration components early and adjusting control parameters before significant vibration occurs. The control device preemptively modifies parameters of the self-excited converter in response to detected vibration trends, preventing the harmful vibration effect before it fully develops while maintaining the beneficial dual-converter power flow capability.
Data Source
AI summary
A power conversion device included in a self-excited DC power transmission system connected to an AC system includes a self-excited converter and a control device. The control device includes: a storage to store first vibration information and a first control parameter of the self-excited converter in association with each other for each of a plurality of pieces of first vibration information, a vibration detector to detect a vibration component of an AC voltage of the AC system; a determination unit to determine whether first similar vibration information similar to first detected vibration information including the vibration component of the AC voltage of the detected AC system exists in the plurality of pieces of first vibration information; and a setting unit to set the first control parameter associated with the first similar vibration information as a new control parameter of the self-excited converter when the first similar vibration information exists.