Generator Frequency Torque Control for Stable Engine-Generator Sets
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Solution Overview
Problem
Existing closed-loop control devices for power assemblies with internal combustion engines and generators have inherent instability due to using dynamic variables, leading to less robust steady-state control behavior and requiring complex adaptations for different power assemblies.
Innovation Solution
A closed-loop control device that uses generator frequency as a controlled variable, determining a control deviation and target torque as a manipulated variable, with an adaptable control rule based on adaptation variables like generator frequency, target torque, and power, allowing for consistent loop gain across operating points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If speed of internal combustion engine is used as controlled variable, then dynamic response is improved, but system robustness deteriorates
Solution Approach 1:
The patent introduces generator frequency as an intermediary controlled variable between engine speed and final control output. The controller detects generator frequency (which is less dynamic and quieter) and determines target torque based on frequency control deviation, thereby mediating the control action to achieve both dynamic response and robustness.
Solution Approach 2:
The patent changes the controlled parameter from engine speed to generator frequency. Since generator frequency is tapped at a less dynamic point and has lower gain, this parameter change inherently improves robustness while maintaining control effectiveness through the adapted control rule.
2Speed
If gain of controlled system is increased, then dynamic control behavior is improved, but steady-state control behavior deteriorates
Solution Approach 1:
The patent changes the controlled parameter to generator frequency, which has significantly lower gain compared to speed control. This allows using a faster controller with larger proportional coefficient without compromising steady-state behavior, as the lower gain of frequency measurement naturally dampens the system response.
3Measurement precision
If control rule is adapted for different power assemblies, then control precision is improved, but device complexity increases
Solution Approach 1:
The patent creates a universal control device that can be applied to different power assemblies without specific tuning. The control rule is adapted as a function of operating points (detected generator frequency, target torque variable, generator power), allowing the same controller to maintain optimal performance across various applications.
Solution Approach 2:
The control rule is made dynamic and adaptive, changing based on operating conditions rather than being fixed for each application. The adaptation variables (generator frequency, target torque, generator power) allow the controller to automatically adjust to different power assembly characteristics without requiring manual reconfiguration.
Data Source
AI summary
A closed-loop control device for closed-loop control of a power assembly is configured for:detecting a generator frequency of a generator;determining a control deviation as a difference between the detected generator frequency and a target generator frequency;determining a target torque as a manipulated variable for controlling an internal combustion engine as a function of the control deviation;using a control rule for determining the target torque; andadapting the control rule—used to determine the target torque—as a function of an adaptation variable, the adaptation variable being the detected generator frequency, a target torque variable, or a generator power, wherein the closed-loop control device can adapt the control rule by determining a proportional coefficient of the control rule such that a predetermined loop gain (vf) of an open control loop is constant, the predetermined loop gain (vf) being: vf=kpf((fG,stat)(30 Mm,stat)).