CN-122015118-A - Wind-powder coupling adjusting system and method based on combustion stability index drive

CN122015118ACN 122015118 ACN122015118 ACN 122015118ACN-122015118-A

Abstract

The invention belongs to the technical field of combustion control and operation optimization of coal-fired boilers, and particularly relates to a wind-powder coupling adjusting system and method based on combustion stability index driving. The invention comprises a hearth state sensing module, a combustion stability index construction module, a coupling control decision module, a small powder bin rapid powder supply execution module, a wind powder cooperative regulation module and a safety degradation module, wherein the invention constructs a quantifiable combustion stability index, realizes second-level compensation of a fuel side by utilizing an independent rapid powder supply channel, and introduces a wind powder cooperative mechanism to dynamically match primary air quantity while rapidly regulating powder so as to ensure that the wind powder balance is not destroyed in the regulation process.

Inventors

XU JUN
WANG YI
SU SHENG
HU SONG
XIANG JUN
CHEN DEZHI
YANG YIQING
CHEN LEI
LI JUNMENG
LIN BOWEN
DENG WEI
XU KAI
JIANG LONG

Assignees

华中科技大学

Dates

Publication Date: 20260512
Application Date: 20260204

Claims (10)

1. The wind-powder coupling regulating system based on combustion stability index driving is characterized by comprising a hearth state sensing module, a combustion stability index constructing module, a coupling control decision module, a small powder bin rapid powder supply executing module, a wind-powder cooperative regulating module and a safety degradation module; The hearth state sensing module comprises a flame detector, a hearth pressure or negative pressure sensor, a burner outlet temperature sensor, a hearth temperature sensor and a smoke analyzer, is used for collecting multi-source combustion state signals in real time, and is used for carrying out time alignment and synchronization in a sampling period of 0.1-1s so as to provide raw data input for constructing a combustion stability index; The combustion stability index construction module comprises a signal preprocessing unit, a sliding window characteristic extraction unit and a multisource characteristic fusion algorithm execution unit, wherein the combustion stability index construction module is used for extracting the pressure fluctuation energy, flame variation coefficient and CO/O 2 deviation characteristic of a hearth, and fusing to generate a combustion stability index in a single scalar or vector form, and dividing a stability zone, an early warning zone and a strong intervention zone according to the combustion stability index; the coupling control decision module comprises a feedback controller, a feedforward compensator, a constraint management unit and an anti-saturation processing logic unit, wherein the coupling control decision module is used for outputting a small powder bin rapid powder supply correction quantity, outputting a primary air or air distribution fine adjustment instruction and ensuring that a control action is executed in a safety boundary; The small powder bin rapid powder supply execution module comprises a small powder bin, a metering powder feeder, a branch regulating valve, a branch rapid opening valve, a check valve, a branch pipeline and a mixing point, wherein the mixing point is arranged before a primary air main pipe enters a combustor distributor, and the compensating pulverized coal supplied by the small powder bin and primary air enter the combustor after being mixed at the mixing point; the wind-powder cooperative regulation module comprises a primary wind regulation valve or variable frequency fan control system, a secondary wind distribution air door executing mechanism and a wind-powder matching calculation unit, and is used for dynamically regulating the primary wind quantity to maintain wind-powder matching, finely regulating local secondary wind distribution and inhibiting local fluctuation; The safety degradation module comprises a sensor health diagnosis unit, an actuator state monitoring unit and a constraint touch detection logic unit, and is used for evaluating the reliability of the sensor and the availability of the actuator in real time, triggering degradation when faults or out-of-limit occur, keeping normal operation of a basic DCS control loop and ensuring a safety base line.
2. A method for adjusting the coupling of wind and powder based on the driving of a combustion stability index, which is implemented based on the wind and powder coupling adjusting system according to claim 1, and is characterized by comprising the following steps: s1, initializing a system and setting parameters; s2, collecting a hearth state signal in real time; S3, constructing a combustion stability index; S4, judging a stable state and triggering control; s5, calculating a quick powder supply correction quantity; S6, executing powder supply of a small powder bin; S7, wind and powder cooperative adjustment; s8, safety monitoring and degradation processing; Step S9, circularly executing; repeating steps S2-S8 according to a set time period to form closed loop regulation.
3. The method according to claim 2, wherein in the step S1, the method comprises: setting the length and the step length of a sliding window, wherein the length of the sliding time window is fixed to be 30s, and the updating step length is fixed to be 1s; configuring a filtering frequency band; Defining a stability index partition threshold; setting the maximum correction amount of the small powder bin, the upper and lower limits of air quantity adjustment and inventory constraint.
4. The wind-powder coupling adjustment method according to claim 3, wherein in the step S2, the furnace status sensing module collects and outputs the following five types of signals: (1) Flame stabilization signal F s (t), output by the flame detector and forming a stabilization measure via its internal algorithm; (2) The hearth pressure signal P (t) is hearth pressure or hearth negative pressure; (3) A hearth temperature signal T (T) is the hearth representative point temperature; (4) A flue gas oxygen signal O 2 (t); (5) A flue gas carbon monoxide signal CO (t); The sampling period is set to be 0.2s for flame stabilizing signals and hearth pressure signals and 1s for hearth temperature, oxygen and CO signals, and all signals are aligned by adopting uniform time stamps to form a sliding time window input sequence.
5. The method of claim 4, wherein in the step S3, the combustion stability index construction module calculates four feature values within a sliding time window, calculates the combustion fluctuation index CBI and the combustion stability index CSI based on the four feature values, and performs index partitioning, and the method specifically comprises: 3.1 feature quantity: (1) Furnace pressure fluctuation intensity Ep: , Wherein P k is the kth pressure sampling value in the sliding window, The average value of the pressure in the sliding window is obtained, and N is the number of samples in the sliding window; (2) Flame coefficient of fluctuation CV f : , Wherein, the For the standard deviation of the flame holding signal in the sliding window, For the average value of the flame holding signal in the sliding window, A constant to prevent zero denominator; (3) CO risk amount R CO : , Wherein, CO avg is the average value of CO in the sliding window, K CO is a CO risk gain coefficient and is an average value of CO change rates in the sliding window; (4) Oxygen amount deviation D O2 : , Wherein, O 2,avg is the average value of O 2 in the sliding window, O 2,set is the oxygen set value, (dO 2 /dt） avg is the average value of the oxygen change rate in the sliding window, and K O2 is the oxygen deviation gain coefficient; 3.2 normalization: Normalization is performed for each feature quantity x: , Wherein x min and x max are setting boundaries of corresponding feature quantities; 3.3 combustion fluctuation index and combustion stability index: , , Wherein CBI is combustion fluctuation index, CSI is combustion stability index, and w1, w2, w3 and w4 are fixed weight parameters; output deviation: , wherein CSI tar is the target stability index; 3.4 index partition: setting a stable area, an early warning area and a strong intervention area: Stable region CSI > = CSI G ; the early warning area is CSI R <=CSI<CSI G ; Strong intervention region CSI < CSI R ; Wherein, CSI G and CSI R are tuning thresholds and are written into DCS parameter tables.
6. The method according to claim 5, wherein in the step S4, If the CSI is in the stable region, maintaining the current control; If the CSI is in the early warning area, starting feedforward compensation; if the CSI is in the strong interference area, activating feedback inhibition control; wherein the feedforward compensation The calculation formula is as follows, and the calculation formula consists of disturbance quantity: , Wherein the method comprises the steps of Representing the load change rate term, As a primary wind disturbance term, the wind turbine generator is provided with a primary wind disturbance table, V PA is primary air quantity, V PA,set is primary air quantity set value, and k L 、K PA 、k O2 is setting parameter; feedback amount in feedback suppression control The calculation formula is as follows by adopting PI: , Wherein K p 、K i is a tuning parameter.
7. The method of claim 6, wherein in step S5, the small powder bin supplies powder in a rapid amount The calculation formula is as follows: , the constrained shaping is performed fixedly and is performed, Clipping: Is limited to , Speed limit: , inventory constraints-when the usable duration of the breadcrumbs bin is below the inventory threshold, Δq max is compressed to a conservative upper limit and smoothly recycled, Anti-saturation, freezing integral term and switching to the conservative parameter set when the output collision limit lasts for 5s, Wherein Δq min 、ΔQ max is a tuning parameter.
8. The method according to claim 7, wherein in the step S6, the small powder bin outputs pulverized coal through the powder feeding device, and the pulverized coal is fed into the mixing position of the burner side through the branch pipeline, so as to realize rapid dynamic adjustment of the fuel side, and the sequence of powder feeding actions of the small powder bin is performed as follows: hot standby, wherein the regulating valve is opened to a pre-opening position u pre , the quick-opening valve is closed, and the powder feeder is in start permission; Starting the powder feeder, climbing the powder feeding amount from 0 to Q ps,set according to a slope R up , and controlling the tracking of the regulating valve; Strong intervention, namely opening the quick-opening valve to an emergency opening u emg , climbing the powder supply quantity to Q according to a slope R strong ps,emg; Smooth recovery, namely, the powder feeding amount falls back to 0 according to a slope R down , a quick-opening valve is closed, a regulating valve returns to a pre-opening position, and the powder feeding machine is stopped; and (3) degrading and exiting, namely closing the branch valve and stopping the powder feeder.
9. The wind-powder coupling adjustment method according to claim 8, wherein in the step S7, the wind-powder cooperative adjustment module uses an equivalent wind-powder matching index R e as a cooperative control object: ; Wherein Q base is the fuel quantity given by a main powder supply system, Q s is the quick powder supply correction quantity of a small powder bin, and V PA is the primary air quantity; The system sets an equivalent wind powder matching index allowable interval [ R e,low ,R e,high ] and a primary wind safety lower limit V PA,min ; the collaboration rule is: When R e >R e,high is a primary air increasing command DeltaV PA , R e is returned to the allowable range; when R e <R e,low and V PA >V PA,min are the primary air reduction command DeltaV PA is output, R e is returned to the allowed interval; When V PA =V PA,min , the primary air is locked and no longer descends, and The upper limit of Q ps is compressed to a conservative upper limit, so that secondary fluctuation caused by wind-powder mismatch is avoided; The secondary air distribution correction adopts a fixed triggering condition that RCO exceeds a CO risk threshold value and lasts for 3s, or Fs (t) continuously descends and lasts for 3s, and after triggering, the secondary air gate executes balanced correction, and the correction amplitude is limited to keep the total air quantity unchanged.
10. The wind-powder coupling adjustment method according to claim 9, wherein in the step S8, the degradation criterion is one of the following conditions: (1) The flame holding signal is not refreshed for more than 2s; (2) The furnace pressure signal is not refreshed for more than 2s; (3) The powder feeder executes feedback and instruction deviation exceeding a threshold value for 5s; (4) The small powder bin level is lower than the lower limit of the level and lasts for 10s; (5) The bypass differential pressure exceeds the occlusion threshold for 5 seconds; The demoting action includes: (1) Entering a degraded exit state; (2) Closing the quick-opening valve and the regulating valve; (3) Stopping the powder feeder; (4) Exiting primary air coordination and secondary air distribution correction; (5) Maintaining a conventional combustion control loop; (6) Generating an alarm and recording an event; the event record comprises a trigger criterion code, a trigger time, a CBI maximum value, a CSI minimum value, an accumulated compensation amount, a degradation duration time and a primary air cooperative accumulated action amount.

Description

Wind-powder coupling adjusting system and method based on combustion stability index drive Technical Field The invention belongs to the technical field of combustion control and operation optimization of coal-fired boilers, and particularly relates to a wind-powder coupling adjusting system and method based on combustion stability index driving. Background Under the construction background of a 'double carbon' target and a novel power system, the deep participation peak regulation of the coal motor group becomes normal. Frequent load change, wide load operation, variable coal quality and other factors, so that dynamic instability phenomena such as short-period pressure oscillation, flame flickering, partial flameout and the like are extremely easy to occur in the combustion process of the furnace. The traditional combustion control system mainly depends on slow parameters such as oxygen quantity, main steam temperature and the like to perform steady-state adjustment, lacks the capability of sensing combustion fluctuation in real time and rapidly inhibiting the combustion fluctuation, and is difficult to cope with second-level and even sub-second-level disturbance. Once the combustion instability is not inhibited in time, serious accidents such as deflagration, fire extinguishment, overheat of a heating surface and the like can be caused, and the safety of a unit and the stability of a power grid are threatened. In order to cope with combustion instability, chinese patent CN111678167B discloses an all-air powder on-line control system of an ultra-supercritical unit, and the pulverized coal distribution angles of all pipelines are automatically adjusted by utilizing an air powder balance distributor through on-line monitoring of the concentration, fineness, primary/secondary air, CO, carbon content of fly ash and the like of pulverized coal, so that static balance of air powder conveying is realized, and combustion uniformity is improved. Chinese patent CN115962478a proposes a full-condition adaptive combustion optimization control method for a coal-fired unit, which constructs a soft measurement model of boiler efficiency, CO, NOx, etc. based on historical operation data, generates optimal combustion parameters (such as coal feeding amount and throttle opening) through multi-objective optimization, and sends the optimal combustion parameters into DCS for execution in a closed loop. The core is data-driven steady-state optimization, and is suitable for economic and environment-friendly operation under different loads. However, in practical application, the prior art scheme still has the defects that firstly, the prior art does not combine dynamic signals such as flame, hearth pressure high-frequency fluctuation and the like, a unified combustion stability criterion cannot be built, slow working condition deviation and dangerous combustion oscillation (such as 0.5-3Hz pressure pulsation) cannot be distinguished, short period instability detection and judgment are inaccurate, secondly, an optimized instruction in the prior art acts on a main coal mill system, response is slow (in minutes) or only distribution proportion is adjusted, total powder supply amount is not changed, global fuel deficiency or overage cannot be dynamically compensated in seconds, combustion fluctuation caused by sudden disturbance is difficult to be restrained, and thirdly, if powder supply is only increased and primary air quantity is not coordinated, local rich powder deficiency or dilute phase transportation is easy to be caused, combustion instability is aggravated, and a new fluctuation source is possibly introduced due to rapid control due to lack of a cooperative mechanism of fuel rapid correction and air quantity synchronous adjustment in the prior art. Disclosure of Invention Aiming at the defects of the prior art, the invention aims to provide a wind-powder coupling adjusting system and method based on combustion stability index driving, which are used for constructing a quantifiable combustion stability index, realizing second-level compensation on the fuel side by utilizing an independent rapid powder supply channel, introducing a wind-powder coordination mechanism, dynamically matching primary air quantity while rapidly adjusting powder, and ensuring that the wind-powder balance is not destroyed in the adjusting process. The technical scheme adopted by the invention is as follows: A wind-powder coupling regulation system based on combustion stability index drive comprises a hearth state sensing module, a combustion stability index construction module, a coupling control decision module, a small powder bin rapid powder supply execution module, a wind-powder cooperative regulation module and a safety degradation module; The hearth state sensing module comprises a flame detector, a hearth pressure or negative pressure sensor, a burner outlet temperature sensor, a hearth temperature sensor and a smoke analyzer, is used for colle