Gas Engine Speed Control via Torque-Based Lambda Correction
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Solution Overview
Problem
Existing methods for automatically controlling stationary gas engines are not optimal in handling fluctuating fuel quality or fuel density, leading to sluggish response times and potential overshooting in engine output adjustments.
Innovation Solution
A method that computes an engine speed control deviation and determines a set torque as a correcting variable, using this torque to adjust the gas throttle angle by varying the set volume flow with a correction factor, which is calculated based on the deviation between actual and limited system torque, ensuring robust operation and maintaining a constant lambda value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the mixture throttle position is changed to adjust power output, then the engine output changes, but the response time becomes sluggish and lambda control becomes delayed
Solution Approach 1:
The patent applies preliminary action by pre-calculating the required gas throttle position based on the desired power output change before the mixture throttle adjustment is complete. The control system anticipates the lambda deviation that will occur and pre-adjusts the gas throttle to compensate, thereby reducing the overall response time and eliminating the sluggishness associated with sequential adjustment.
Solution Approach 2:
The patent implements feedback control by continuously monitoring the actual lambda value and comparing it to the target lambda. Based on this feedback, the control system dynamically adjusts the gas throttle position to maintain the correct air-fuel ratio during transient operations. This closed-loop feedback mechanism eliminates the delay in lambda control by making real-time corrections.
2Reliability
If the gas throttle position is adjusted to maintain lambda, then the lambda value is maintained, but the correcting variables may overshoot under certain conditions
Solution Approach 1:
The patent applies partial action by adjusting the gas throttle only to the extent necessary to maintain lambda, rather than making full compensatory adjustments. The control system calculates the precise amount of gas throttle adjustment needed based on the current operating conditions and lambda deviation, avoiding excessive correction that would cause overshooting. This selective, measured adjustment maintains stability while preventing precision errors.
3Reliability
If sequential iterative adjustment of mixture throttle and gas throttle is performed, then lambda control is achieved, but the system complexity and control time increase
Solution Approach 1:
The patent merges the control of the mixture throttle and gas throttle into a coordinated system. Instead of treating them as separate sequential adjustments, the control system simultaneously considers both throttle positions and their interactions. This combined control approach achieves accurate lambda control while reducing the overall control time and simplifying the control logic by eliminating the need for separate iterative adjustment cycles.
Data Source
AI summary
A method for automatically controlling a stationary gas engine, where an engine speed control deviation is computed from a set engine speed (nSL) and an actual engine speed (nIST), and a set torque is determined as a correcting variable from the speed control deviation by a speed controller, where a set volume flow is determined as a function of the set torque to establish a mixture throttle angle (DKW1, DKW2) and a gas throttle angle, and where the set volume flow is varied to adjust the gas throttle angle by a correction factor.