Variable Gain PI Control for Fuel Gas Temperature Stability
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Solution Overview
Problem
Conventional gas turbine fuel gas heating control systems face instability in combustion gas temperature during load fluctuations, leading to unstable combustion states and reduced combustion efficiency due to inadequate adjustment of the time constant and gain in PI control.
Innovation Solution
The fuel gas heating control equipment incorporates a heater, a first gas system, a second gas system for bypassing the heater, a temperature-detecting element, and a bypass flow control valve with a bypass flow control portion that adjusts the flow rate using PI control, dynamically changing the gain and time constant based on generator output to stabilize fuel gas temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the time constant and gain in PI control are kept fixed, then the control system is simple, but the fuel gas temperature becomes unstable during load fluctuations
Solution Approach 1:
The patent applies dynamics by making the PI control parameters (gain and time constant) variable rather than fixed. The control system dynamically adjusts these parameters based on the generator output load, using different gain and time constant values for different operating conditions (e.g., during load changes versus steady-state operation). This resolves the contradiction by enabling temperature stability across varying loads while maintaining reasonable control complexity through structured parameter schedules.
Solution Approach 2:
The patent directly applies parameter changes by modifying the PI control gain and time constant values according to the operating condition. When the generator output changes, the system selects appropriate parameter sets to maintain optimal control performance. This allows the system to adapt to different load conditions and maintain fuel gas temperature stability without requiring an overly complex control architecture.
2Reliability
If the gain and time constant are adjusted dynamically, then the fuel gas temperature stability improves, but the control system complexity increases
Solution Approach 1:
The system dynamically adjusts control parameters based on generator output, implementing different gain and time constant values for different operating modes. This dynamic adaptation stabilizes combustion state during load fluctuations while keeping the control logic structured and manageable through predefined parameter schedules rather than complex real-time calculations.
Solution Approach 2:
The patent implements parameter changes by systematically varying PI control parameters according to operating conditions. The control algorithm selects from predefined gain and time constant sets based on generator output, achieving combustion stability without requiring excessively complex control logic. This structured parameter adaptation balances performance improvement with control system simplicity.
3Ease of operation
If a fixed PI control is used, then the control system is easy to implement, but the temperature fluctuation range increases during load changes
Solution Approach 1:
The patent implements parameter changes by using different PI control gain and time constant values for different operating conditions. During load changes, the system uses parameter sets optimized for transient response, while during steady-state operation, it uses sets optimized for stability. This approach effectively reduces temperature fluctuation range while maintaining reasonable implementation complexity through structured parameter selection.
Solution Approach 2:
The system dynamically adapts control parameters to match operating conditions, making the control behavior appropriate for each state. This dynamic parameter adjustment reduces temperature fluctuations during load transitions while keeping the control system implementable through predefined parameter schedules rather than complex real-time optimization algorithms.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution improves fuel gas temperature stability during load fluctuations, reduces temperature fluctuations at maximum output, and enhances combustion efficiency by maintaining a stable combustion state.
Implementation Method 1
a heater (6) for heating the fuel gas
Data Source
AI summary
A fuel gas heating control equipment in accordance with the present invention is provided with a gain-determining portion 21 and a time-constant-determining portion 22 which determine values of a gain and a time constant to be used for PI calculations being performed by a PI calculation portion 14. The gain-determining portion 21 specifies a small time constant for the PI calculation portion 14 during load fluctuations when the generator output increases, and specifies a large time constant for the PI calculation portion 14 when the generator output reaches the maximum output. In consequence, during load fluctuations, responsiveness is good and a rapid change in temperature can be followed, so that a fuel gas temperature will not fluctuate in response to a slight change in temperature at the maximum output, thereby achieving a stable fuel gas temperature.