HVDC Commutation Failure Prediction Using Risk Factor and Future States
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Solution Overview
Problem
Conventional commutation failure prediction methods in HVDC systems are limited by their reliance on present-instant measurements, ignoring transient changes, leading to low prediction speed and susceptibility to missed predictions, thus limiting the accuracy of commutation failure prevention.
Innovation Solution
A rapid prediction method for commutation failure in HVDC systems using a commutation failure risk factor, which integrates real-time and future-instant characteristic quantities, calculates conventional and advanced commutation areas, and adapts weight coefficients based on prediction errors to enhance prediction speed and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional commutation failure prediction methods use present-instant measurements only, then the prediction method is simple, but the prediction speed is low and prediction accuracy is limited
Solution Approach 1:
The patent performs preliminary calculations of future-instant commutation voltage and DC current using prediction models before the actual commutation failure occurs. By pre-calculating these parameters and their corresponding commutation areas, the system enables faster prediction response without waiting for the fault instant to arrive, thus resolving the contradiction between simplicity and speed.
Solution Approach 2:
The patent dynamically adjusts the prediction horizon and recalculates commutation areas at multiple future instants based on system state changes. This dynamic approach allows the prediction method to adapt to transient changes in real-time, improving prediction speed while maintaining reasonable computational complexity through selective recalculation only when necessary.
2Device complexity
If conventional prediction methods ignore transient changes from present to future instant, then the calculation is simple, but the prediction accuracy is limited and missed predictions occur
Solution Approach 1:
The patent preliminarily predicts future-instant commutation voltage and DC current values using system models before the actual fault occurs. By pre-calculating these transient values and using them to determine commutation areas at future instants, the method captures transient changes that would otherwise be missed, thereby improving prediction accuracy without excessive computational complexity.
Solution Approach 2:
The patent incorporates feedback mechanisms where prediction errors from previous calculations are used to adjust and optimize future predictions. This feedback loop refines the prediction models for commutation voltage and DC current, improving accuracy by learning from past transient behavior patterns while keeping the calculation complexity manageable through iterative optimization.
3Loss of time
If the prediction time is extended beyond half a power frequency cycle, then more transient changes can be captured, but the conventional method becomes insufficient and fails to predict accurately
Solution Approach 1:
The patent extends the prediction horizon beyond half a power frequency cycle by preliminarily calculating commutation areas at multiple future instants. This preliminary action enables the system to predict commutation failures occurring further in advance while maintaining reliability through the use of prediction models that account for transient changes over the extended time horizon.
Solution Approach 2:
The patent maintains continuous prediction capability over extended time horizons by continuously updating the prediction models and recalculating commutation areas at successive future instants. This continuous useful action ensures that prediction reliability is maintained even when extending the prediction time beyond conventional limits, as the system continuously tracks transient changes throughout the extended horizon.
Data Source
AI summary
Disclosed are a rapid prediction method and system for a commutation failure in a high voltage direct current transmission system (HVDC) based on a commutation failure risk factor, belonging to the technical field of commutation failure prevention in the high voltage direct current transmission system. The method can rapidly predict whether the commutation failure occurs after a fault occurs in a line-commutated converter-HVDC (LCC-HVDC) system, thereby supporting the subsequent prevention of the commutation failure. During the implementation, the method defines a conventional commutation area and an advanced commutation area, and calculates a commutation failure risk factor by integrating the conventional commutation area and the advanced commutation area, thereby predicting the commutation failure. In the method, the present-instant information and the future-instant information of characteristic quantities are comprehensively considered during a prediction process, thereby improving the commutation failure prediction speed.