Condensate Flow Rate Control for Power Plant Frequency Response
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Solution Overview
Problem
Conventional power plants face challenges in maintaining high precision and responsiveness to frequency fluctuations and load changes due to delays in steam system control, particularly in dispersed power sources where frequency fluctuations occur rapidly.
Innovation Solution
A condensate flow rate control device that adjusts pressure in the condensate flow path to control the amount of bleed steam from the steam turbine, improving responsiveness and precision in conforming to frequency fluctuations and load changes without the need for additional control valves, by utilizing a water level adjustment unit to calculate setting values based on input fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional steam system control (governor valve opening control, fuel flow rate control, feed water flow rate control) is used for frequency control, then the power plant can respond to frequency fluctuations, but the response is delayed due to dead time and combustion delay, preventing swift fluctuation suppression
Solution Approach 1:
The invention extracts the frequency control function from the slow-responding steam system and transfers it to the fast-responding condensate system. By controlling the condensate flow rate to the deaerator in response to frequency fluctuations, the system achieves rapid frequency regulation without the dead time and combustion delay inherent in fuel control systems.
Solution Approach 2:
Instead of controlling the steam input to the turbine (conventional approach), the invention inverts the control strategy by regulating the condensate return flow to the deaerator. This reverse approach allows the condensate system, which has minimal delay, to become the primary frequency control mechanism, bypassing the slow thermal response of the boiler-fuel system.
2Measurement precision
If governor valve opening control is used for frequency control, then frequency fluctuations can be stabilized, but the control precision is insufficient when frequency fluctuations are significant, necessitating additional steam system control
Solution Approach 1:
The invention merges the governor valve control system with the condensate flow rate control system into a unified frequency control mechanism. The condensate flow rate control device works in conjunction with the governor valve, combining the rapid response of condensate control with the existing steam flow control to achieve both high precision and reliability in frequency stabilization.
Solution Approach 2:
The control system functions as a composite control mechanism, where the condensate control component provides fast response for precision frequency regulation, while the steam system component provides robust frequency stabilization. This composite approach leverages the strengths of both systems to overcome the limitations of either system alone.
3Ease of operation
If the deaerator water level is adjusted to control condensate flow rate, then the feed water storage amount is maintained constant during stable operation, but additional control complexity is introduced for frequency and load control
Solution Approach 1:
The deaerator water level adjustment valve is given multiple functions: it maintains feed water storage during stable operation and simultaneously controls condensate flow rate for frequency and load control. By making this existing valve multi-functional, the system avoids adding separate control devices, thereby reducing overall control system complexity while achieving enhanced control capabilities.
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 enhances the precision and responsiveness of power output control, reducing output deviations during high load changes and frequency fluctuations, and allows for stable operation by temporarily extracting energy from the steam turbine, thus improving the overall control of the power plant.
Implementation Method 1
adjusts pressure in a condensate flow path from the deaerator water level adjustment valve to the deaerator so as to control an amount of bleed steam from the steam turbine
Data Source
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AI summary
[Problem] To provide a condensate flow rate control device and control method for a power plant that improve responsiveness to frequency fluctuations or requested load changes, that can reduce frequency fluctuations with precision, or that can improve the precision with which the output power conforms to requested load instructions. [Solution] A power plant equipped with a condensate flow rate control device (36) is provided with a deaerator (32) into which condensate generated in a condenser (26) is supplied via a deaerator water level adjustment valve (34) and into which the bleed steam from a steam turbine (18) is introduced. The condensate flow rate control device (36) has a water level adjustment means (40) for conducting condensate flow rate control. The water level adjustment means (40) adjusts the pressure in the condensate flow path from the deaerator water level adjustment valve (34) to the deaerator (32) so that input frequency fluctuations are suppressed, or so that the output value of a generator (12) conforms to input requested load changes, thereby adjusting the amount of bleed steam from the steam turbine (18).