Multi-terminal VSC-HVDC Coordination Control for Voltage Stability
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Solution Overview
Problem
Multi-terminal VSC-HVDC power transmission systems face challenges in coordination control, leading to voltage instability and reliability issues, particularly when the direct current voltage master control station shuts down, resulting in system failure or oscillations.
Innovation Solution
A coordination control method where a direct current voltage master control station controls the system, and at least one slave station takes over if the master station fails, using inter-station communications to switch control modes, ensuring stable direct current voltage control with or without deviations, and allowing common converter stations to maintain original control modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single point direct current voltage coordination control mode is used, then the system structure is simple and control is easy, but the system reliability deteriorates because the whole system exits operation when the master control station shuts down
Solution Approach 1:
The patent divides the voltage control function into multiple independent control stations (master control station and slave control stations) instead of relying on a single control point. Each station can independently perform voltage control, creating segmented control capabilities that prevent system-wide failure when one station shuts down.
Solution Approach 2:
The patent pre-configures multiple slave control stations with the capability to take over voltage control functions. These stations are prepared in advance with control algorithms and communication interfaces, so when the master control station fails, the takeover can occur immediately without system collapse.
2Reliability
If a direct current voltage slope-based multi-point coordination control mode is used, then the power adjusting capacity and stability are improved, but the direct current voltage quality deteriorates because it becomes nonconstant
Solution Approach 1:
The patent implements dynamic role assignment where control stations can switch between master and slave roles based on system conditions. The master control station provides constant voltage control when operational, while slave stations provide dynamic support. This dynamic configuration allows the system to maintain voltage quality while preserving stability capabilities.
Solution Approach 2:
The patent introduces an intermediary control mechanism where the master control station acts as the primary voltage regulator maintaining constant voltage, while slave control stations provide secondary support. This intermediary structure allows the system to benefit from both constant voltage control and multi-point stability support without the drawbacks of pure slope-based control.
3Reliability
If a direct current voltage deviation-based multi-point coordination control mode is used, then the system stability is improved compared to single point control, but the voltage control precision deteriorates due to slower detection and larger oscillations during takeover
Solution Approach 1:
The patent implements real-time feedback communication between control stations and the central control system. The master control station continuously monitors system voltage and communicates with slave stations, enabling precise detection of voltage deviations. This feedback mechanism allows for rapid response with high precision, avoiding the slower detection and larger oscillations of deviation-based control.
Solution Approach 2:
The patent merges the advantages of single-point constant voltage control with multi-point stability support. The master control station provides precise constant voltage control similar to single-point control, while slave stations provide additional stability support. This combination achieves both high voltage control precision and improved system stability.
Data Source
AI summary
The present invention discloses a coordination control method of a multi-terminal VSC-HVDC transmission system. If a direct current voltage master control station shuts down, a direct current voltage control slave station takes over direct current voltage control, and remaining convertor stations keep original control modes. The takeover steps comprise that under the condition that inter-station communications are effective, the master control station sends a shutdown message to the slave station through the inter-station communications, and when the slave station monitors that the direct current voltage master control station shuts down, the slave station switches a current control mode into a direct current voltage control mode; and under the condition that inter-station communications fail or inter-station communications are absent, the slave station monitors changes of the direct current voltage of a system.