Gas Turbine Fuel Control Combustion Oscillation Suppression
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Solution Overview
Problem
Conventional fuel control devices for gas turbines struggle to accurately adjust fuel distribution ratios during rapid load changes, leading to potential combustion oscillations that can damage the combustor and gas turbine components.
Innovation Solution
A fuel control device with an IGV response correction unit, combustion temperature estimation value calculation unit, and valve opening calculation unit is implemented to correct inlet guide vane openings and calculate actual fuel distribution command values based on real-time atmospheric conditions and gas turbine output, ensuring accurate fuel distribution and preventing combustion oscillations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the fuel control device uses conventional turbine inlet temperature estimation based on atmospheric pressure, atmospheric temperature, IGV opening command value, and gas turbine output value, then the estimation is simple to calculate, but the estimation value does not keep pace with rapid changes in actual turbine inlet temperature, causing operation lines to enter combustion oscillation regions
Solution Approach 1:
The patent applies preliminary action by calculating a preliminary turbine inlet temperature estimation value using conventional methods before the rapid load change occurs. This preliminary estimation serves as a baseline that is then corrected based on the actual load change amount and IGV opening change amount, allowing the system to anticipate and compensate for temperature deviations before they cause combustion oscillation
Solution Approach 2:
The patent implements feedback by continuously monitoring the actual gas turbine output value and comparing it with the commanded output value to determine the load change amount. This feedback loop allows the system to detect rapid load changes and adjust the fuel distribution ratio accordingly, correcting the temperature estimation to reflect actual conditions and preventing operation lines from entering combustion oscillation regions
2Ease of operation
If the fuel distribution ratio is adjusted during rapid load changes to follow the target operation line, then the turbine inlet temperature control is simplified, but the actual operation line may still enter combustion oscillation regions due to estimation delays
Solution Approach 1:
The patent applies preliminary anti-action by calculating a correction amount for the turbine inlet temperature estimation value before the actual temperature deviation occurs. This correction is based on the load change amount and IGV opening change amount, which are available in advance during rapid load changes. The corrected estimation is then used to adjust the fuel distribution ratio, preventing the operation line from entering combustion oscillation regions rather than merely responding after the problem occurs
3Adaptability or versatility
If the system uses a target operation line to guide fuel distribution ratios, then the control strategy is straightforward, but rapid load changes cause the actual operation line to deviate into combustion oscillation regions
Solution Approach 1:
The patent applies dynamics by making the fuel distribution ratio adjustment dependent on the rate of load change. During rapid load changes, the system dynamically adjusts the fuel distribution ratio at a larger magnitude to quickly bring the operation line back toward the target operation line. During gradual load changes, smaller adjustments are made. This dynamic adjustment strategy allows the system to adapt to varying load change rates while maintaining combustion stability
Data Source
AI summary
An IGV opening command value is corrected to calculate an actual opening equivalent value that indicates an approximate value of an actual opening. A temperature estimation value, for a case where a mixture of fuel and in-flowing air is combusted, is calculated using the actual opening equivalent value, atmospheric conditions, and an output from a gas turbine. A fuel distribution command value that indicates distribution of fuel output from a plurality of fuel supply systems is calculated on the basis of the temperature estimation value. The fuel distribution command value and a fuel control signal command value that indicates the total flow rate of fuel to be output to the plurality of fuel supply systems are acquired, and respective valve openings of fuel flow rate regulating valves of the fuel supply systems are calculated on the basis of the fuel distribution command value and the fuel control signal command value.