Coordinated Air-Fuel Controller for Gas Turbines
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Solution Overview
Problem
Existing gas turbine control systems face challenges in coordinating air and fuel supply due to a non-intuitive relationship between turbine speed error and exhaust temperature error, making it difficult to design and tune cross channel controllers, which operate in 'control error space' rather than 'demand space'.
Innovation Solution
A coordinated air-fuel controller with a cross channel controller operating in 'demand space' uses an air versus fuel model to coordinate air and fuel supply, allowing for a direct relationship between air and fuel, making it easier to design and tune, and reflecting constraints within the fuel supply controller.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cross channel controller operates in control error space using turbine speed error and exhaust temperature error, then the controller can regulate turbine performance parameters, but the non-intuitive relationship between speed error and temperature error makes the controller difficult to design and tune
Solution Approach 1:
The patent transforms the control variables from error space parameters (speed error, temperature error) to demand space parameters (fuel demand, air demand). This parameter transformation simplifies the control relationship by making it more intuitive and direct, thereby reducing controller design and tuning complexity while maintaining reliable turbine performance regulation
2Productivity
If the cross channel controller uses processed speed error signal and temperature error signal with transfer functions, then the controller can generate air supply control signals, but the indirect error-space operation reduces coordination accuracy between air and fuel supply
Solution Approach 1:
Instead of operating in the traditional error space where control signals are derived from error signals through complex transfer functions, the patent inverts the approach by operating directly in demand space. This allows the controller to directly coordinate air and fuel demands based on intuitive relationships, improving coordination accuracy while maintaining control signal generation capability
Data Source
AI summary
A fuel controller, and associated method, provides a fuel control output signal to a fuel control actuator to control operations. The fuel controller determines the fuel control output signal based on rotational speed error. A combustion air controller provides a combustion air control output signal to a combustion air control actuator to control operations. A cross channel controller is in communication with the fuel controller and the combustion air controller. The cross channel controller provides a combustion air control modification signal to the combustion air controller. The combustion air control modification signal is determined from the fuel control output signal using an air versus fuel model. The combustion air controller determines a preliminary combustion air control signal based on an exhaust temperature error, and further determines the combustion air control output signal based on both of the preliminary combustion air control signal and the combustion air control modification signal.