Gas Turbine Feedforward Control for Compressor Failure
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Solution Overview
Problem
Existing power plant control systems are too slow to respond to unexpected transients, leading to sudden shutdowns of major rotating equipment when a fuel gas compressor fails, resulting in high stress and potential delays in restarting the plant.
Innovation Solution
A method that rapidly reduces the power output of gas turbine engines to an emergency power output upon detection of a fuel gas compressor failure, using feedforward control signals to quickly adjust fuel flow and maintain operation until redundant compressors can take over.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If pressure controllers and load control systems are designed to work slowly to avoid steep pressure gradients and oscillations, then stable operation of gas turbine engines is achieved, but the control systems cannot respond quickly enough to unexpected transients such as fuel gas compressor failures
Solution Approach 1:
The control system is equipped with feedforward control that anticipates compressor failures and preemptively adjusts fuel control valve positions and gas turbine power output before the failure fully impacts the system. This preliminary action prevents the transient pressure drops that would otherwise cause sudden shutdowns, thereby maintaining stability while enabling fast response to failures.
2Productivity
If fuel gas compressors are operated close to full load to improve plant economics, then investment cost and self-consumption are optimized, but failure of a compressor results in fast drop of fuel gas supply pressure causing sudden shutdown of gas turbine engines
Solution Approach 1:
Upon detection of compressor failure, the feedforward control system immediately reduces gas turbine power output to match the reduced fuel gas supply capacity. This prevents fuel gas pressure from dropping below the minimum required pressure threshold, allowing the gas turbine engines to continue operating reliably at reduced capacity rather than shutting down suddenly.
Solution Approach 2:
The control system dynamically adjusts the operating point of the gas turbine engines in response to compressor failure. By continuously modulating fuel control valve positions and power output based on real-time compressor status, the system maintains reliable operation across varying conditions, transitioning smoothly from full-load operation to failure-mode operation without sudden shutdowns.
3Duration of action of stationary object
If sudden shutdown of gas turbine engines is prevented through fast control response, then lifetime consumption of thermally loaded parts is reduced, but the control system complexity increases
Solution Approach 1:
The feedforward control system uses pre-programmed control strategies and lookup tables that define the relationship between compressor failure scenarios and required gas turbine power adjustments. This approach provides fast protective action to preserve equipment lifetime while avoiding the need for complex real-time calculations or advanced control algorithms, thereby limiting control system complexity.
Data Source
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AI summary
Disclosed is a method for operating a power plant (1) comprising at least one gas turbine engine (10, 20) and at least one fuel gas compressor (53. 54, 55). The method comprises supplying fuel gas (5) through a utility supply line (51), compressing the fuel gas to a plant supply pressure in at least one operating fuel gas compressor and supplying the compressed fuel gas to a plant supply line (52). The at least one gas turbine engine is operated at a set power output according to a power demand signal. If a failure of an operating fuel gas compressor is detected, the power output of the at least one gas turbine engine is reduced to an emergency power output which is lower than the set power output and the power output of the at least one gas turbine engine is restricted to the emergency power output. The reduction of the power output is performed in one single step and controlled by at least one feedforward control signal.