DC Transmission Commutation Control via Dynamic Trigger Delay
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Solution Overview
Problem
Existing DC transmission systems face commutation failures and stability issues during large transient disturbances due to the inadequacy of the maximum trigger delay angle determination methods in current technologies, which can lead to increased DC current and reduced voltage, causing system instability and potential converter blocking.
Innovation Solution
A commutation control method that detects transient disturbances and adjusts the maximum trigger delay angle by determining a smaller angle based on actual DC current and voltage conditions, using formulas such as AMAX=180°-arccos[cos(γo-2*dx*Io/IdN*Udi0/N*Udi0-K*(Io-Id)) or AMAX=180°-arccos[cos(γo+Δγ)-2*dx*Io/IdN*Udi0/N*Udi0-K*(Io-Id)), to prevent commutation failures and maintain voltage stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a maximum trigger delay angle determined in the related art is adopted when large transient disturbance occurs, then the DC voltage is increased to reduce DC current, but commutation failure or blocking of the current converter occurs
Solution Approach 1:
The patent implements dynamic adjustment of the maximum trigger delay angle based on real-time system conditions. When large transient disturbance is detected, the control method dynamically reduces the maximum trigger delay angle to a smaller value, whereas under normal conditions a larger angle is used to maintain voltage stability. This dynamic adaptation prevents commutation failure during disturbances while ensuring stable operation during normal conditions.
Solution Approach 2:
The patent changes the parameter of maximum trigger delay angle based on system state. By detecting large transient disturbance and switching to a smaller maximum trigger delay angle, the system adapts its operational parameters to avoid commutation failure. The method includes determining a smaller maximum trigger delay angle when disturbance is detected, which changes the commutation characteristics to prevent failure.
Data Source
AI summary
Provided are a commutation control method and a commutation control apparatus. The method includes: detecting whether transient disturbance in a DC transmission system satisfies a disturbance criterion condition; when the transient disturbance satisfies the disturbance criterion condition, determining a maximum trigger delay angle used in a commutation operation performed by a current converter on an inverter side of the DC transmission system, the determined maximum trigger delay angle being smaller than a maximum trigger delay angle used before the transient disturbance; and controlling the current converter on the inverter side of the DC transmission system to perform the commutation operation based on the determined maximum trigger delay angle.