CN108415470B - Liquid level-flow nonlinear area control method based on fuzzy system - Google Patents
Liquid level-flow nonlinear area control method based on fuzzy system Download PDFInfo
- Publication number
- CN108415470B CN108415470B CN201810138010.XA CN201810138010A CN108415470B CN 108415470 B CN108415470 B CN 108415470B CN 201810138010 A CN201810138010 A CN 201810138010A CN 108415470 B CN108415470 B CN 108415470B
- Authority
- CN
- China
- Prior art keywords
- liquid level
- set value
- control
- flow
- change
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Classifications
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
- G05D9/00—Level control, e.g. controlling quantity of material stored in vessel
- G05D9/12—Level control, e.g. controlling quantity of material stored in vessel characterised by the use of electric means
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
- G05D7/00—Control of flow
- G05D7/06—Control of flow characterised by the use of electric means
- G05D7/0617—Control of flow characterised by the use of electric means specially adapted for fluid materials
- G05D7/0623—Control of flow characterised by the use of electric means specially adapted for fluid materials characterised by the set value given to the control element
Abstract
The invention discloses a liquid level-flow nonlinear area control method based on a fuzzy system, and belongs to the technical field of process industrial production. Aiming at the process characteristics of continuous production among rectifying towers in the chemical production process industry, combining fuzzy control and nonlinear area control, dividing a liquid level control interval, and adjusting the set value of a flow controller in advance according to the liquid level variation, the variation rate and other parameters, the area where the liquid level is located and the variation condition of the liquid level. The method has certain intelligence and self-adaptive functions. The method aims at the change degree of the deviation of the process controlled variable, adjusts the set value of the liquid level controller in real time to achieve the aim of adjusting the change of the control action intensity, and simultaneously changes the change direction of the set value according to the change direction of the liquid level to achieve the effect of adjusting in advance, thereby realizing the intelligent nonlinear area control of the liquid level-flow.
Description
Technical Field
The invention belongs to the technical field of process industrial production, and relates to a nonlinear area control method of a liquid level-flow control loop of a process industrial production device.
Background
Along with the gradual improvement of the modernization, automation and integration level of the process industrial production device, the relationship between production devices and equipment is tighter and tighter. Because of the continuity of production operation, the discharge of the former equipment is often directly used as the feed of the latter equipment, for example, two rectifying towers for continuous production, the liquid level at the bottom of the tower is usually controlled in a liquid level-flow cascade manner, the outflow at the bottom of the upstream rectifying tower is the feed of the downstream rectifying tower, and the feed is required to be changed as slowly as possible or unchanged in order to keep the production stability of the downstream rectifying tower. However, due to the production continuity, if the working condition of the upstream changes, the liquid level-flow cascade control of the upstream rectifying tower is difficult to avoid fluctuation of the bottom flow of the upstream rectifying tower due to untimely and effective adjustment, so that the fluctuation of the feeding amount of the downstream rectifying tower is caused, and the high-precision stable control of the downstream rectifying tower is influenced. Aiming at the liquid level-flow cascade control loops which are mutually related and mutually influenced at the upstream and the downstream, a liquid level control interval is divided by combining fuzzy control and nonlinear area control, and a flow set value is adjusted in advance according to parameters such as liquid level variation, change rate and the like, so that a rectifying tower liquid level-flow nonlinear area control method based on a fuzzy system is formed, the problem of large flow fluctuation of the liquid level-flow control loops is reduced, and the influence on downstream equipment is reduced.
Disclosure of Invention
In a liquid level-flow cascade control loop of upstream and downstream equipment of a process industrial production device, due to working condition change, liquid level-flow cascade control is not timely and effective in adjustment, so that flow fluctuation is large, and downstream production is affected. Aiming at the problem, the invention provides a liquid level-flow nonlinear area control method based on a fuzzy system, aiming at the process characteristics of continuous production among rectifying towers in the chemical production process industry, combining fuzzy control and nonlinear area control, dividing a liquid level control interval, and adjusting the set value of a flow controller in advance according to the area of the liquid level and the change condition of the liquid level according to parameters such as liquid level variation, change rate and the like. The specific strategy is as follows:
according to the set value of the liquid level, the liquid level is divided into three intervals, namely a fine adjustment area A, a fine adjustment area B and a coarse adjustment area C.
(1) A fine tuning area A: the fine adjustment interval value is a, and the liquid level measurement value is in the range of a set value SV-a and a set value SV + a;
(2) fine adjustment area B: the fine adjustment interval value is b, wherein b > a, the liquid level measured value is within the range of a set value SV-b and a set value SV-a, or the liquid level measured value is within the range of a set value SV + a and a set value SV + b;
(3) a coarse adjustment zone C: the coarse adjustment interval value is c, wherein c > b, and the liquid level measured value is within the range of a set value SV-c and a set value SV-b, or within the range of a set value SV + b and a set value SV + c.
For different liquid level intervals, the specific control strategy is as follows:
(1) when the liquid level is in the fine adjustment area A, adjusting the flow set value at a rate which is half of the reference rate set value according to the liquid level change condition;
(2) when the liquid level is in the fine adjustment area B, adjusting the flow set value at a reference rate according to the liquid level change condition;
(3) when the liquid level is in the rough adjusting area C, adjusting the flow set value at a rate which is twice of the reference rate set value according to the liquid level change condition;
(4) and setting a speed change factor of the flow set value according to the liquid level variation in the current control period, wherein the variation rate of the flow set value is the product of the speed change factor and the regulation rate.
And designing a two-input single-output fuzzy controller according to a control strategy of a fuzzy system, wherein input variables are a liquid level measured value and a liquid level variable quantity, and output variables are a flow set value variable quantity.
Based on the upper and lower limits and the variable quantity of the liquid level, a fuzzification method of the liquid level interval and the liquid level variable quantity is formulated: the liquid level interval is represented by A \ B \ C, SV represents a set value, [ A-, A + ] represents a fine adjustment area, [ B-, A- ] [ A +, B + ] represents a fine adjustment area, [ C-, B- ] [ B +, C + ] represents a coarse adjustment area, C + is equal to the upper liquid level limit, and C-is equal to the lower liquid level limit. Fuzzification processing is carried out on liquid level input variables:
l + + represents that the liquid level changes greatly in a forward direction in a sampling period, and L + represents that the liquid level changes little in the forward direction in a sampling period; 0 indicates no change in liquid level; l-represents the negative small change of the liquid level in one sampling period; l-represents the negative large change of the liquid level in one sampling period; fuzzification processing is carried out on the liquid level variable quantity:
obtaining a fuzzy control table according to the liquid level and the fuzzy quantity of the liquid level variable quantity:
obtaining an output variable U from a fuzzy control table:
U＝{3.6,2,1.8,1,0.9,0.5,0,-0.5,-0.9,-1,-1.8,-2,-3.6}
converting the output fuzzy quantity into a final set value variable quantity:
i denotes the number of control cycles, SVi+1Set value for the i +1 th control period, SViIs the set value of the ith control period, and V is the set value change rate.
Compared with the traditional PID controller, the method provided by the invention has the following advantages:
the method has certain intelligence and self-adaptive functions. The method aims at the change degree of the deviation of the process controlled variable, adjusts the set value of the liquid level controller in real time to achieve the aim of adjusting the change of the control action intensity, and simultaneously changes the change direction of the set value according to the change direction of the liquid level to achieve the effect of adjusting in advance, thereby realizing the intelligent nonlinear area control of the liquid level-flow.
Drawings
FIG. 1 is a schematic view of a liquid level control interval.
FIG. 2 is a schematic diagram of a two-input single-output fuzzy controller.
FIG. 3 is a comparison of the first embodiment of the rectifying column.
FIG. 4 is a second comparison between before and after the implementation of the rectifying column.
Detailed Description
The method proposed by the present invention is described below with reference to an example.
The nonlinear region control method designed by the invention is implemented on a loop consisting of a tower bottom liquid level control loop LIC330161 and a tower bottom outlet flow control loop FIC330202 of a rectification tower object of a certain refinery. The fine tuning region of the liquid level LIC340022 was set to [54,56], the fine tuning regions were set to [52,54], [56,58], the coarse tuning regions were set to [10,52], [58,90], and the flow set point tuning rate was set to 2.4/hr.
Before and after control effect is implemented, for example, as shown in fig. 3 and 4, the lic330161.pv is measured value of liquid level, and the fic330202.pv is bottom flow; it can be obviously seen that the output flow fluctuation of the tower bottom is large before the nonlinear region control is implemented, the stable production of the downstream is influenced, and after the nonlinear region control is implemented on the liquid level, the fluctuation condition of the output flow of the tower bottom is obviously improved, and the fluctuation is slowed down to a large extent.
Claims (1)
1. A liquid level-flow nonlinear area control method based on a fuzzy system is characterized in that: aiming at the process characteristics of continuous production among rectifying towers in the chemical production process industry, combining fuzzy control and nonlinear area control, dividing a liquid level control interval, and adjusting the set value of a flow controller in advance according to the area where the liquid level is located and the change condition of the liquid level according to parameters such as liquid level variation, change rate and the like; the specific strategy is as follows:
dividing the liquid level into three intervals, namely a fine adjustment area A, a fine adjustment area B and a coarse adjustment area C according to the set value of the liquid level;
(1) a fine tuning area A: the fine adjustment interval value is a, and the liquid level measurement value is in the range of a set value SV-a and a set value SV + a;
(2) fine adjustment area B: the fine adjustment interval value is b, wherein b > a, the liquid level measured value is within the range of a set value SV-b and a set value SV-a, or the liquid level measured value is within the range of a set value SV + a and a set value SV + b;
(3) a coarse adjustment zone C: the coarse adjustment interval value is c, wherein c > b, and the liquid level measured value is within the range of a set value SV-c and a set value SV-b, or within the range of a set value SV + b and a set value SV + c;
for different liquid level intervals, the specific control strategy is as follows:
(1) when the liquid level is in the fine adjustment area A, adjusting the flow set value at a rate which is half of the reference rate set value according to the liquid level change condition;
(2) when the liquid level is in the fine adjustment area B, adjusting the flow set value at a reference rate according to the liquid level change condition;
(3) when the liquid level is in the rough adjusting area C, adjusting the flow set value at a rate which is twice of the reference rate set value according to the liquid level change condition;
(4) setting a speed change factor of a flow set value according to the liquid level variation in the current control period, wherein the variation rate of the flow set value is the product of the speed change factor and the regulation rate;
designing a two-input single-output fuzzy controller according to a control strategy of a fuzzy system, wherein input variables are a liquid level measured value and a liquid level variable quantity, and output variables are a flow set value variable quantity;
based on the upper and lower limits and the variable quantity of the liquid level, a fuzzification method of the liquid level interval and the liquid level variable quantity is formulated: the liquid level interval is represented by A \ B \ C, SV represents a set value, [ A-, A + ] represents a fine adjustment area, [ B-, A- ] [ A +, B + ] represents a fine adjustment area, [ C-, B- ] [ B +, C + ] represents a coarse adjustment area, C + is equal to the upper liquid level limit, and C-is equal to the lower liquid level limit; fuzzification processing is carried out on liquid level input variables:
l + + represents that the liquid level changes greatly in a forward direction in a sampling period, and L + represents that the liquid level changes little in the forward direction in a sampling period; 0 indicates no change in liquid level; l-represents the negative small change of the liquid level in one sampling period; l-represents the negative large change of the liquid level in one sampling period; fuzzification processing is carried out on the liquid level variable quantity:
obtaining a fuzzy control table according to the liquid level and the fuzzy quantity of the liquid level variable quantity:
obtaining an output variable U from a fuzzy control table:
U＝{3.6,2,1.8,1,0.9,0.5,0,-0.5,-0.9,-1,-1.8,-2,-3.6}
converting the output fuzzy quantity into a final set value variable quantity:
i denotes the number of control cycles, SVi+1Set value for the i +1 th control period, SViIs the set value of the ith control period, and V is the set value change rate.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810138010.XA CN108415470B (en) | 2018-02-10 | 2018-02-10 | Liquid level-flow nonlinear area control method based on fuzzy system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810138010.XA CN108415470B (en) | 2018-02-10 | 2018-02-10 | Liquid level-flow nonlinear area control method based on fuzzy system |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN108415470A CN108415470A (en) | 2018-08-17 |
| CN108415470B true CN108415470B (en) | 2022-03-01 |
Family
ID=63128296
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201810138010.XA Active CN108415470B (en) | 2018-02-10 | 2018-02-10 | Liquid level-flow nonlinear area control method based on fuzzy system |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN108415470B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110754937A (en) * | 2019-10-11 | 2020-02-07 | 珠海格力电器股份有限公司 | Water drainage control method and device for water purifying dispenser, storage medium and water purifying dispenser |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH03160213A (en) * | 1989-11-20 | 1991-07-10 | Sumitomo Electric Ind Ltd | Automatic burner for shaft furnace, fuzzy theory applied thereto |
| JPH07259745A (en) * | 1994-03-24 | 1995-10-09 | Meidensha Corp | Refluent water control method for rainwater stagnating pond |
| CN103412482A (en) * | 2013-06-09 | 2013-11-27 | 苏州经贸职业技术学院 | Dynamic fuzzy control system and control method thereof |
| CN106468879A (en) * | 2016-09-22 | 2017-03-01 | 北京世纪隆博科技有限责任公司 | A kind of liquid level flow nonlinear area control method |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7621141B2 (en) * | 2004-09-22 | 2009-11-24 | York International Corporation | Two-zone fuzzy logic liquid level control |
-
2018
- 2018-02-10 CN CN201810138010.XA patent/CN108415470B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH03160213A (en) * | 1989-11-20 | 1991-07-10 | Sumitomo Electric Ind Ltd | Automatic burner for shaft furnace, fuzzy theory applied thereto |
| JPH07259745A (en) * | 1994-03-24 | 1995-10-09 | Meidensha Corp | Refluent water control method for rainwater stagnating pond |
| CN103412482A (en) * | 2013-06-09 | 2013-11-27 | 苏州经贸职业技术学院 | Dynamic fuzzy control system and control method thereof |
| CN106468879A (en) * | 2016-09-22 | 2017-03-01 | 北京世纪隆博科技有限责任公司 | A kind of liquid level flow nonlinear area control method |
Non-Patent Citations (1)
| Title |
|---|
| "一种新型模糊液位控制及其应用";甄新平等;《化工学报》;20080731;第59卷(第7期);正文第1-3节 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN108415470A (en) | 2018-08-17 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN104595885B (en) | Station boiler Minimum Flowrate of Feed Pump recycle valve control method | |
| CN104753439B (en) | A kind of PID intelligent speed-regulating methods of motor | |
| CN106468879B (en) | A kind of liquid level-flow nonlinear area control method | |
| CN105182740B (en) | Raw material grinding autocontrol method | |
| JP2002523821A (en) | Controller for determining optimal tuning parameters used in a process control system and method of operating the controller | |
| CN108415470B (en) | Liquid level-flow nonlinear area control method based on fuzzy system | |
| CN103576711B (en) | Based on the chemical reactor temperature-controlled process that quantitative one-parameter PID controls | |
| CN105373065A (en) | Dry fog dedusting control system and method | |
| CN109368760B (en) | Method for realizing self-adaptive control of wastewater pH in DCS | |
| US5831850A (en) | Method and device for control over an admissable range with contextual anticipation using fuzzy logic | |
| CN107589662B (en) | Main steam pressure adjusting method and main steam pressure adjusting system | |
| JP2004163003A (en) | Control method of air separator | |
| CN105836421B (en) | A kind of multistage solid-handling equipment inter-linked controlling method | |
| CN112680789A (en) | HVPE temperature control system and method based on fuzzy control | |
| CN110595153A (en) | Control method for air feeding amount in automatic load changing process of air separation device | |
| CN103344115B (en) | Novel sintering machine speed control method | |
| CN108980438B (en) | Bivalve Staged cotrol method and control device | |
| CN108379867B (en) | Intelligent nonlinear area control method for liquid level-flow of rectifying tower by combining expert system | |
| CN104950847B (en) | The computational methods of the self-optimizing controlled variable of forced-circulation evaporation control process in alkali liquor concentration production technology | |
| CN108187362A (en) | A kind of rectifying column beacon flint control method | |
| CN108132596A (en) | A kind of advanced broad sense intelligence internal model collection PID controller design method of differential | |
| CN110243138B (en) | Air separation equipment model feedforward control system and method | |
| CN103713664B (en) | Sewage treatment control method, device, system and sewage treatment facility | |
| CN113082759A (en) | Automatic control system and control method for bromine distillation tower | |
| CN107777416A (en) | A kind of constant tension control system based on fuzzy |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |