Gas Turbine Compressor Surge Control via Variable Geometry
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Solution Overview
Problem
Gas turbine engine compressors operating at constant speed face challenges in controlling surge margin, especially during rapid transients and variable load conditions, due to limitations in existing control systems for bleed off valves and variable inlet geometry vanes.
Innovation Solution
A control logic system that adjusts the position of variable geometry compressor mechanisms, such as bleed off valves and variable inlet guide vanes, to maintain a target surge margin by integrating steady-state and transient schedules, allowing for independent scheduling of compressor operations to maximize power, efficiency, and life during steady-state conditions while preserving surge margin during transients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a compressor operates at constant speed to drive an electric power generator, then the generator produces stable frequency AC electricity, but the compressor cannot effectively respond to rapid transient conditions and maintain surge margin
Solution Approach 1:
The patent applies dynamics by making the compressor geometry variable through VIGVs and BOVs that can adjust their positions in real-time. This allows the compressor to adapt its effective geometry during transient conditions, enabling it to maintain surge margin while operating at constant speed for generator applications.
Solution Approach 2:
The control system is segmented into independent control mechanisms for VIGVs and BOVs, each controlled separately to manage different aspects of compressor performance. This segmentation allows independent optimization of inlet guide vane positioning and bleed valve control during transient events.
2Reliability
If existing control systems modulate bleed off valves and variable inlet guide vanes, then compressor surge margin is maintained, but the control effectiveness is limited during rapid transients at constant speed
Solution Approach 1:
The control system performs preliminary action by detecting transient conditions early and preemptively adjusting VIGV and BOV positions before the compressor reaches dangerous operating conditions. This proactive control enhances response effectiveness during rapid transients.
Solution Approach 2:
The system uses feedback from compressor operating parameters to continuously monitor surge margin and dynamically adjust VIGV and BOV positions. This closed-loop feedback control ensures effective surge margin maintenance while improving response to transient conditions.
3Device complexity
If a single control scheme is used for both steady-state and transient conditions, then device complexity is reduced, but optimal performance during both conditions cannot be achieved
Solution Approach 1:
The control scheme is segmented into separate steady-state control and transient control pathways. This allows each control mode to be optimized independently for its specific operating conditions while maintaining overall system manageability and avoiding excessive complexity.
Solution Approach 2:
The control system dynamically switches between or combines steady-state and transient control strategies based on operating conditions. This dynamic adaptation enables optimal performance during both steady-state and transient conditions without requiring a single overly complex control scheme.
Data Source
AI summary
A gas turbine engine is disclosed that has with two or more compressors. A first one of the compressors include a compressor variable geometry mechanism that may be in the form of adjustable vanes, bleed valves, or the like. A first one of the compressors is turned at a first speed and the second one of the compressors is turned at a second speed. The first speed is maintained approximately constant while the second speed varies and position of the compressor variable geometry mechanism is modulated in accordance with the second speed of the second one of the compressors to regulate surge margin for the first one of the compressors.