Compressor Fuel Gas Control Device for Rapid Load Variation
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Solution Overview
Problem
Existing fuel gas supply systems face challenges in stabilizing pressure during rapid load variations, such as load interruptions, due to overshoot and undershoot in pressure control, requiring improved response characteristics.
Innovation Solution
A control device and method that incorporate a main pressure control unit using feedforward and feedback control values, and an emergency pressure control unit adding a bias value to the anti-surge valve control, to rapidly stabilize pressure by adjusting the inflow amount and anti-surge valve operation based on load variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional feedback control is used to maintain discharge pressure, then pressure stability is achieved under normal operation, but response to rapid load variation is slow and causes overshoot/undershoot
Solution Approach 1:
The feedforward control unit calculates a control value based on the load variation amount before the pressure deviation occurs, enabling the system to anticipate and respond to load changes proactively. This preliminary action allows the control valve to adjust the fuel gas flow rate in advance, preventing pressure overshoot and undershoot while maintaining stability.
Solution Approach 2:
The feedback control unit continuously monitors the discharge pressure and calculates a control value based on the deviation from the target pressure. This feedback mechanism ensures that any residual pressure deviations are corrected, maintaining pressure stability while working in conjunction with feedforward control to handle rapid load variations.
2Loss of time
If only feedback control is used, then pressure stability is maintained, but time is required to correct pressure deviations during interruption
Solution Approach 1:
By calculating the control value based on load variation amount before pressure deviation occurs, the system eliminates the time delay inherent in pure feedback control. The feedforward control unit enables immediate response to load changes, reducing the time required to stabilize pressure while maintaining control accuracy through subsequent feedback correction.
3Reliability
If anti-surge valve is opened rapidly to avoid surging, then compressor safety is protected, but pressure stability deteriorates due to oscillation
Solution Approach 1:
The feedback control unit continuously monitors discharge pressure and adjusts the anti-surge valve opening based on the pressure deviation. This closed-loop control prevents the oscillatory behavior caused by rapid valve opening, as the valve position is continuously refined to maintain pressure stability while still protecting the compressor from surging conditions.
Solution Approach 2:
The control system replaces purely mechanical valve actuation with an intelligent control algorithm that calculates optimal valve positioning based on load variation and pressure feedback. This substitution of mechanical reaction with calculated control enables smoother valve operation that maintains both compressor safety and pressure stability.
Data Source
AI summary
A control device (101) that controls a fuel gas supply system (100) that comprises: a compressor (1) that supplies compressed fuel gas to a load apparatus (15); an inflow amount regulating means (5) that regulates the amount of fuel gas that flows into the compressor (1); and an anti-surge valve (7) that is for returning to an inlet side of the compressor (1) fuel gas that is discharged from the compressor (1). The control device (101) comprises: a main pressure-control unit (101a) that controls the inflow amount regulating means (5) and the anti-surge valve (7) on the basis of a feedforward control value that is generated on the basis of the load of the load apparatus (15) and of a prescribed conversion process, and on the basis of a feedback control value that is generated on the basis of the deviation between a set value and a measured value for the discharge pressure of the compressor (1); and an emergency pressure-control unit (101b) that calculates a bias-added control value that is found by adding a predetermined bias value to an anti-surge valve control value that is for controlling the anti-surge valve (7) and that is calculated on the basis of at least one of the feedforward control value and the feedback control value, and that, on the basis of the occurrence of load variations that are at or above a prescribed value, switches between the anti-surge control value and the bias-added control value and controls the anti-surge valve (7).