CN-121995730-A - Dual-mode intelligent switching and adjusting method and system for pneumatic induced draft fan based on mode interlocking

CN121995730ACN 121995730 ACN121995730 ACN 121995730ACN-121995730-A

Abstract

The invention discloses a mode interlocking-based dual-mode intelligent switching and adjusting method and system for a steam-driven induced draft fan, and belongs to the technical field of thermal automatic control of thermal power plants. The invention comprises constructing dual-mode architecture of parallel rotational speed PID control channel and rotational speed stepping control channel in distributed control system, selecting one to output to rotational speed controller via a logic selection module, setting inter-channel undisturbed tracking logic and mutual exclusion locking logic between rotational speed PID automatic and moving blade automatic, providing mutually exclusive rotational speed PID mode and rotational speed stepping mode for selection by operator, and establishing command based on moving blade The composite fault diagnosis model of the feedback deviation and the hearth negative pressure deviation judges that the movable blade is jammed when the threshold condition is continuously met, automatically executes a degradation flow, forcibly cuts into a full manual safety state, supports manual switching to a rotating speed PID mode as emergency backup, and puts into a normal operation mode after the fault is removed. The invention realizes the unification of high-efficiency vibration prevention and high fault tolerance.

Inventors

Da Xuanlong
HU SHIMING
SUN DAWEI
ZHANG LINGHAN
CHEN DESHENG
WANG JINWEI
WANG SIYANG
Lan Siying

Assignees

西安热工研究院有限公司
华能(福建)能源开发有限公司福州分公司

Dates

Publication Date: 20260508
Application Date: 20260127

Claims (10)

1. The method for intelligently switching and adjusting the double modes of the pneumatic induced draft fan based on mode interlocking is characterized by comprising the following steps of: s1, constructing a dual-mode parallel control architecture and initializing The method comprises the steps of constructing a dual-channel parallel control architecture in a DCS system, wherein the dual-channel parallel control architecture comprises a rotating speed PID control channel, a corresponding rotating speed PID manual operator and a rotating speed stepping control channel, and corresponds to the rotating speed stepping manual operator; the final output instructions of the rotating speed PID control channel and the rotating speed stepping control channel are selected and output through a logic selection module, and the channel selection of the selection module is controlled by a mode enabling signal, wherein the mode enabling signal comprises a rotating speed PID mode enabling signal and a rotating speed stepping mode enabling signal; s2, starting preparation and mode manual selection When the pneumatic induced draft fan finishes the flushing and receives the remote control instruction, the movable blade and the two rotating speed manual operators are both placed in a manual state, a target operation mode is selected at the moment, and an operation interface provides two enabling keys, namely a rotating speed PID mode enabling mode and a rotating speed stepping mode enabling mode; If the 'rotational speed PID mode enabling' is selected, the DCS system enters a rotational speed PID regulation mode, the rotational speed PID manual operator is put into automatically, the rotational speed PID manual operator controls the negative pressure of the hearth through continuously regulating the rotational speed, at the moment, the movable vanes are automatically locked, the rotational speed stepping manual operator keeps a manual tracking state, and the output value of the rotational speed PID manual operator is followed in real time, so that undisturbed preparation is realized for potential mode switching; If the rotating speed stepping mode is selected, the DCS system enters a preparation state, and when the rotating speed stepping is automatically input and kept manual, the DCS system executes a fixed rotating speed-rotating blade adjusting strategy; s3, fault detection and automatic security degradation During the running period of the rotation speed stepping-movable blade cooperative regulation mode, the DCS continuously monitors the state of the movable blade executing mechanism, and when the fault judging condition is met simultaneously and the preset time delay is continuously reached for 60 seconds, the occurrence of the movable blade jamming fault is judged; s4, manual emergency switching stage After the DCS system enters a full manual safe state due to failure, the state of the unit is manually adjusted to adjust the rotating speed and the movable blades, if automatic control is required to be recovered to maintain the operation of the unit, the button of the rotating speed adjusting mode enabling is manually clicked, the movable blades are kept in a manual state, the rotating speed is automatically adjusted at the moment, the rotating speed PID adjusting mode is entered, namely the rotating speed PID regulator takes over and maintains the negative pressure of a hearth to be stable, and the continuous operation of the unit is ensured as an emergency backup control means; s5, overhauling reset and process restarting And after the maintenance of the movable vane executing mechanism is recovered to be normal, executing the reset operation of the DCS system, namely putting the movable vane manual operator and the two rotating speed manual operators into a manual mode, and recovering the DCS system to an initial selection state.
2. The method for intelligent switching and adjusting of a dual-mode intelligent switching and adjusting of a pneumatic induced draft fan based on mode interlocking according to claim 1, wherein in step S1, a dual-channel parallel control architecture built-in multiple interlocking logic comprises: The channel interlocking, namely the rotational speed PID control channel and the rotational speed stepping control channel are mutually exclusive, when one of the channels is put into automation, the other is automatically and forcedly switched to a manual tracking mode, and the other is output along with the main channel in real time, so that preparation is made for undisturbed switching; the adjusting right interlock comprises that the rotation speed PID automatic adjustment is mutually exclusive with the automatic adjustment of the movable blade, when the rotation speed PID manual operator is put into automation, the automatic function of the movable blade manual operator is logically locked, otherwise, when the movable blade manual operator is put into automation, the automatic function of the rotation speed PID manual operator is locked.
3. The mode-interlock-based dual-mode intelligent switching and adjusting method for the pneumatic induced draft fan according to claim 2, wherein when a rotational speed PID mode enabling signal is activated and a rotational speed PID manual operator, a rotational speed gear manual operator and a movable blade manual operator are in a manual state, a selection module outputs a rotational speed PID manual operator instruction and shields the rotational speed gear manual operator instruction; When the rotating speed stepping mode enabling signal is activated and the rotating speed PID manual operator, the rotating speed stepping manual operator and the movable blade manual operator are in a manual state, the selecting module outputs a rotating speed stepping manual operator command, and the rotating speed PID manual operator command signal is shielded.
4. The method for intelligent switching and adjusting a dual mode of a pneumatic induced draft fan based on mode interlock according to claim 1, wherein in step S2, when all of the following allowable conditions for the gear shift control are satisfied at the same time, the input gear shift control is to activate the gear shift logic, comprising: the operation signal of the induced draft fan is effective; The fan operation signal is valid; Fast without receiving boiler load shedding RB instruction; the absolute value of the difference between the current actual rotating speed of the fan and the target gear rotating speed set according to the current load is not more than 100 rpm.
5. The method for intelligently switching and adjusting the dual modes of the pneumatic induced draft fan based on the mode interlocking according to claim 4 is characterized in that in the step S2, if any one of the allowable conditions of the gear shift control is not met, the rotation speed gear shift logic is kept standby and is forbidden to put into the gear shift control, at the moment, the fixed rotation speed-movable blade adjusting strategy is performed in a degrading way equivalent to a DCS system, the rotation speed is kept unchanged at a current value, the negative pressure is independently adjusted by the movable blade, and the mode can be switched to the gear shift mode after all the conditions are met.
6. The mode-interlock-based dual-mode intelligent switching and adjusting method for a pneumatic induced draft fan according to claim 1, wherein in step S3, the fault determination condition is specifically: |DV|= |moving blade instruction-moving blade feedback|/range 100%>15%; |Dp|= |negative pressure set point-negative pressure actual value| >200 Pa; after the fault is judged, the DCS system immediately executes an automatic safety degradation flow: a. forcedly withdrawing the automatic adjustment of the movable blade, and controlling the movable blade to be cut manually; b. forced withdrawal of the automatic rotation speed stepping adjustment, and cutting the rotation speed control to manual operation; c. the DCS system enters a full manual safety state and triggers an alarm.
7. The method for intelligently switching and adjusting the double modes of the pneumatic induced draft fan based on the mode interlocking according to claim 1 is characterized in that in the step S4, the method further comprises the steps of selecting a rotating speed stepping adjustment mode from the step S2 again and putting into a normal rotating speed stepping-movable blade cooperative adjustment mode according to a safety condition judging mechanism so as to enable a unit to recover economic and vibration-proof operation.
8. Steam-driven induced draft fan bimodulus intelligence switches governing system based on mode interlocking, its characterized in that includes: constructing a dual-mode parallel control architecture and an initialization unit, wherein the dual-channel parallel control architecture is constructed in a DCS system and comprises a rotating speed PID control channel, a corresponding rotating speed PID manual operator and a rotating speed stepping control channel, and corresponds to the rotating speed stepping manual operator; the final output instructions of the rotating speed PID control channel and the rotating speed stepping control channel are selected and output through a logic selection module, and the channel selection of the selection module is controlled by a mode enabling signal, wherein the mode enabling signal comprises a rotating speed PID mode enabling signal and a rotating speed stepping mode enabling signal; The starting preparation and mode manual selection unit is used for selecting a target running mode at the moment when the pneumatic induced draft fan finishes the flushing and receives the remote control instruction and the movable blade and the two rotating speed manual operators are both in a manual state, and the operating interface provides two enabling keys, namely a rotating speed PID mode enabling mode and a rotating speed stepping mode enabling mode; If the 'rotational speed PID mode enabling' is selected, the DCS system enters a rotational speed PID regulation mode, the rotational speed PID manual operator is put into automatically, the rotational speed PID manual operator controls the negative pressure of the hearth through continuously regulating the rotational speed, at the moment, the movable vanes are automatically locked, the rotational speed stepping manual operator keeps a manual tracking state, and the output value of the rotational speed PID manual operator is followed in real time, so that undisturbed preparation is realized for potential mode switching; If the rotating speed stepping mode is selected, the DCS system enters a preparation state, and when the rotating speed stepping is automatically input and kept manual, the DCS system executes a fixed rotating speed-rotating blade adjusting strategy; The DCS system continuously monitors the state of the movable blade executing mechanism during the operation of the rotation speed gear-movable blade cooperative regulation mode, and judges that the movable blade is jammed when simultaneously meeting the fault judging condition and continuously reaching the preset delay time for 60 seconds; The manual emergency switching stage unit is used for manually adjusting the rotating speed and the movable blades after the DCS system enters a full manual safety state due to faults, and manually clicking a rotating speed adjusting mode enabling button if automatic control is required to be restored to maintain the operation of the unit; And the maintenance resetting and flow restarting unit is used for executing the resetting operation of the DCS system after the maintenance of the movable blade executing mechanism is recovered to be normal, and the movable blade manual operator and the two rotating speed manual operators are both placed in a manual mode, so that the DCS system is recovered to an initial selection state.
9. The mode-interlock-based dual-mode intelligent switching and adjusting system for a pneumatic induced draft fan according to claim 8, wherein the construction of the dual-mode parallel control architecture and the initialization unit, the built-in multiple interlock logic of the dual-channel parallel control architecture comprises: The channel interlocking, namely the rotational speed PID control channel and the rotational speed stepping control channel are mutually exclusive, when one of the channels is put into automation, the other is automatically and forcedly switched to a manual tracking mode, and the other is output along with the main channel in real time, so that preparation is made for undisturbed switching; the adjusting right interlock comprises that the rotation speed PID automatic adjustment is mutually exclusive with the automatic adjustment of the movable blade, when the rotation speed PID manual operator is put into automation, the automatic function of the movable blade manual operator is logically locked, otherwise, when the movable blade manual operator is put into automation, the automatic function of the rotation speed PID manual operator is locked.
10. The mode-interlock-based dual-mode intelligent switching and adjusting system for the pneumatic induced draft fan according to claim 9, wherein when a rotational speed PID mode enabling signal is activated and the rotational speed PID manual operator, the rotational speed gear manual operator and the movable blade manual operator are in a manual state, the selection module outputs a rotational speed PID manual operator instruction and shields the rotational speed gear manual operator instruction; When the rotating speed stepping mode enabling signal is activated and the rotating speed PID manual operator, the rotating speed stepping manual operator and the movable blade manual operator are in a manual state, the selecting module outputs a rotating speed stepping manual operator command, and the rotating speed PID manual operator command signal is shielded.

Description

Dual-mode intelligent switching and adjusting method and system for pneumatic induced draft fan based on mode interlocking Technical Field The invention belongs to the technical field of thermal automatic control of thermal power plants, and particularly relates to a dual-mode intelligent switching and adjusting method and system for a steam-driven induced draft fan based on mode interlocking. Background The pneumatic induced draft fan is a key device for guaranteeing the negative pressure stability of a boiler hearth, and the regulation performance of the pneumatic induced draft fan is directly related to the safe and economic operation of a unit. Currently, the main regulation strategies mainly exist in the following three categories, and each has significant limitations. And a continuous rotating speed regulating strategy for controlling the negative pressure of the hearth by directly regulating the rotating speed of the steam turbine. The strategy responds quickly and is directly controlled. However, when the unit load changes frequently, the fan speed will inevitably repeatedly cross the natural resonance interval of the rotor system, thereby inducing vibrations of long-term, high amplitude. The structure safety of equipment such as the fan body and the connecting pipeline is seriously threatened, the service life of key parts is greatly shortened, and the potential unplanned outage risk is formed. And a fixed rotating speed-movable blade regulating strategy, namely keeping the rotating speed of the fan constant and completely maintaining the negative pressure of the hearth by regulating the opening degree of the movable blade. Although the strategy thoroughly avoids resonance problems caused by rotation speed changes, new defects are introduced. Under the low-load working condition, the movable blades are operated at a smaller opening degree for a long time, the operation efficiency of the fan is obviously reduced, and the extra station power consumption is caused, so that the economy of the unit is influenced. More seriously, the strategy places all the regulating pressure on the movable blade executing mechanism, and once the problems of mechanical jamming, connecting rod faults and the like occur, the negative pressure regulating function is immediately lost, and the unit is possibly forced to stop. The scheme is used for presetting the rotating speed of the fan at a plurality of fixed gears (such as high, medium and low three gears) avoiding resonance areas according to the load level of a unit, and the negative pressure is finely regulated through the movable blades. The method combines the advantages of avoiding resonance and improving partial load efficiency. However, the real-time control of the negative pressure is still completely dependent on the movable blade mechanism, the fundamental failure risk of the movable blade jamming is not solved, and the reliability bottleneck of the regulating system still exists. The current technology suffers from the fact that the above strategy is exclusively implemented under traditional DCS architecture, since on-site speed controllers (such as MEHs) are typically only capable of receiving a single speed command signal. The prior art lacks a top-level architecture which can safely and undisturbed arrange two sets of rotating speed control logics in parallel in the same control system and can perform intelligent switching and strict interlocking according to operation requirements or equipment states. The emergency backup guarantee of the rotating speed PID mode can not be obtained while the unit enjoys the high efficiency and vibration-proof advantages of the rotating speed stepping mode, and the overall reliability of the system is provided with a short board. Disclosure of Invention Aiming at the technical problems that the operation efficiency, vibration safety and fault tolerance of a pneumatic induced draft fan cannot be considered on the premise of a single control instruction outlet in the prior art, the invention provides an intelligent switching and adjusting system and method based on dual-mode parallel and mode interlocking. The invention realizes coexistence, interlocking and safe switching of two control modes through a unique DCS internal architecture design, and ensures that the unit has optimal or available adjusting means under any working condition. In order to achieve the above purpose, the present invention adopts the following technical scheme: a dual-mode intelligent switching and adjusting method of a pneumatic induced draft fan based on mode interlocking comprises the following steps: s1, constructing a dual-mode parallel control architecture and initializing The method comprises the steps of constructing a dual-channel parallel control architecture in a DCS system, wherein the dual-channel parallel control architecture comprises a rotating speed PID control channel, a corresponding rotating speed PID manual operator and a rotatin