Variable Frequency Steam Expander Control for Stable Power Output
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Solution Overview
Problem
Power generating devices using positive displacement steam expanders face challenges in maintaining high output due to fluctuations in differential pressure between primary and secondary side steam, leading to reduced output and difficulty in controlling rotation speed without altering torque.
Innovation Solution
A power generating device comprising a positive displacement steam expander, a power generator, operational frequency setting means, a power detector, and control means that adjusts the operational frequency based on detected power deviations to maintain target output, allowing for increased rotation speed without changing torque, thereby sustaining high output regardless of steam pressure differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the differential pressure between primary side steam and secondary side steam is increased to maximize power generator output, then the power generator can operate at rated output, but the output is reduced when secondary side steam pressure increases
Solution Approach 1:
The patent applies dynamics by making the power generator's operational frequency variable rather than fixed. The control means dynamically adjusts the operational frequency in response to changes in differential pressure, allowing the system to adapt to varying secondary side steam pressures while maintaining optimal power output. This resolves the contradiction by enabling the power generator to maintain rated output across different pressure conditions through continuous frequency adjustment.
Solution Approach 2:
The patent changes the operational parameter (frequency) of the power generator to maintain optimal performance. By varying the operational frequency based on differential pressure conditions, the system can compensate for pressure variations and sustain high power output. This parameter change approach allows the power generator to adapt to different operating conditions without being constrained by fixed frequency settings.
2Power
If the rotation speed of the positive displacement steam expander is increased to increase power output, then the output can be increased, but the torque changes which affects the flat characteristic
Solution Approach 1:
The patent applies dynamics by dynamically adjusting the operational frequency to compensate for torque changes when rotation speed varies. The control means monitors power output and adjusts frequency to maintain optimal operating conditions even as rotation speed changes. This allows the system to increase power output through speed variation while the frequency adjustment compensates for torque fluctuations, preserving the desired flat output characteristic.
Solution Approach 2:
The patent implements feedback control where the control means continuously monitors the power generator's operational parameters and adjusts the operational frequency based on detected deviations from target performance. This feedback mechanism ensures that when rotation speed changes to increase power output, the frequency adjustment compensates for torque variations, maintaining stable and predictable power generation characteristics.
3Power
If the operational frequency of the power generator is fixed to maintain stable operation, then the system is simple to operate, but the output cannot be sustained when differential pressure changes
Solution Approach 1:
The patent implements feedback control where the control means continuously monitors power output and operational parameters, automatically adjusting the operational frequency to maintain target performance. This feedback mechanism sustains high power output across varying differential pressure conditions without requiring complex manual intervention, as the system self-regulates through automated frequency adjustment based on real-time conditions.
Solution Approach 2:
The patent applies self-service by enabling the power generation system to automatically adjust its own operational parameters. The control means autonomously modifies the operational frequency in response to changing conditions, allowing the system to sustain optimal performance without external intervention. This self-adjusting capability maintains consistent power output while avoiding the need for complex external control systems.
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
The solution enables the power generator to maintain maximum output and desired flat output characteristics by controlling rotation speed without altering torque, ensuring consistent electric power generation irrespective of secondary side steam pressure, and facilitates integration with utility frequency systems.
Implementation Method 1
a positive displacement steam expander for converting expansion of steam into a rotational force
Implementation Method 2
a power generator connected to a rotational axis of the positive displacement steam expander
Data Source
AI summary
A power generating device according to the present invention has a positive displacement steam expander for converting expansion of steam into a rotational force, a power generator connected to a rotational axis of the positive displacement steam expander, an inverter for setting an operational frequency of the power generator, a power detector for detecting generated electric power of the power generator, and control means for changing set frequency of the inverter in accordance with a deviation of the generated electric power detected by the power detector from a target value. According to such a configuration, it is possible to sustain high output of the power generator irrespective of a differential pressure between primary side steam and secondary side steam.