Gas Turbine VSV Control for Transient Overshoot Mitigation
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Solution Overview
Problem
Gas turbine engines face issues with transient overshoots during maneuvers, leading to component degradation and increased maintenance needs, as existing control systems are designed for worst-case scenarios and do not account for engine variations or hardware changes.
Innovation Solution
A method involving the use of two matrices to predict and mitigate overshoots by adjusting the angular positions of variable-pitch stator vanes, allowing for real-time control during transient maneuvers, independent of the actuation system, and capable of self-learning and recalibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If schedules are designed around a fully deteriorated worst case engine, then safety criteria and reliability are improved, but transient overshoot increases causing component degradation and maintenance issues
Solution Approach 1:
The control system performs preliminary action by predicting the overshoot magnitude and timing before it occurs, then preemptively adjusts the VSV angular position to counteract the anticipated overshoot, thereby preventing component degradation while maintaining safety margins
Solution Approach 2:
The system transitions from static schedules designed for worst-case scenarios to dynamic real-time control that continuously monitors engine parameters, predicts overshoot events, and adjusts VSV positions dynamically based on actual engine state and deterioration level
2Ease of operation
If schedules are used for brand new engines without adjustment, then control simplicity is maintained, but transient overshoot occurs leading to reduced component life
Solution Approach 1:
The control system performs self-service by automatically adapting to the engine's actual deterioration level through continuous monitoring and prediction, eliminating the need for manual schedule adjustments while extending component life through optimized transient control
Solution Approach 2:
The system changes control parameters in real-time based on engine deterioration state, transitioning from fixed schedules to adaptive control that modifies VSV angular positions according to actual engine conditions, thereby extending component life without compromising operational simplicity
3Power
If fast transient overshoot is allowed during slam acceleration, then power and efficiency objectives are met, but thermal gradients cause detrimental effects on component life and coating integrity
Solution Approach 1:
The control system applies preliminary anti-action by predicting the thermal overshoot before it occurs and preemptively adjusting VSV positions to reduce the rate of temperature rise, thereby preventing excessive thermal gradients that would damage components and coatings while maintaining power output objectives
Data Source
AI summary
A method of controlling settings of one or more actuatable gas turbine engine components includes: providing a first matrix which relates reduction in the operational parameter maximum value during the transient manoeuvre to settings of the component(s); providing a second matrix which relates the operational parameter maximum values attained during the transient manoeuvre: time to attain the maximum value after transient manoeuvre initiation, and operational parameter rate of change at the time of the maximum value; monitoring the engine in operation to identify a start of a transient manoeuvre; predicting, on the basis of the second matrix maximum values, an overshoot operational parameter amount during the identified transient manoeuvre and a time the overshoot occurrence; selecting a setting, using the first matrix, to eliminate the predicted overshoot; and applying the setting to the component(s) for a predetermined period around the predicted time of occurrence to reduce or avoid the overshoot.