DE102008007802A1 - Method and device for controlling manipulated variables in metallurgical plants - Google Patents

Abstract

the requirements for the control of various control variables in metallurgical plants have become so high that often the required control ratio of actuators (valves, etc.) is much larger than available on the market. In order to be able to set a larger desired control variable always secure and reproducible with optimal and improved control quality with commercially available actuators with a small control range, the realization of the largest possible control range for the total supply amount according to the invention proposes to use an actuator circuit (8), in the at Hochregeln from a manipulated variable (4) = x to the existing actuator (51) with variable control variable (71) at least one other actuator (52) with a freely selectable fixed control variable (72) is connected in parallel and from this manipulated variable (4) = x the total supply amount is set by the fixed set control variable (72) and the variable control variable (71) combined.

Description

The The invention relates to a method and a device for regulation different control variables in metallurgical Plants such as steel mills, continuous casters, Rolling mills for the example control of hydraulic, electrical and also pneumatic devices with a control system, with the out of the command and the Return variable the calculation performed a deviation and performed a new manipulated variable for the controlled system is given, with the existing example of a valve Actuator implements the control variable, with the then the total supply amount of For example, hydraulic oil, water, air, electrical voltage or current from the given supply is regulated.

At the Operation of metallurgical plants are a series of Regulations of different control variables for Control of hydraulic, electrical and pneumatic Drives necessary, which are directly or indirectly on the inner as well as the external quality of the Affect the final product. As an example, here is the spray cooling On the one hand the inner quality due to the speed the Durcherstarrung influenced, as well as outer Quality the surface of the final product. The Quality (control quality), with which all regulations, involved in the production of continuously cast products, Setting their control variables is of great importance Importance.

In many cases are the requirements of these regulations meanwhile become so high that the manufacturers of actuators (Valves, etc.) used in continuous casters, can no longer meet these requirements. For the control of the spray water are on the market only control valves available, which has a control ratio over allow the controlled system of maximum 1:15, where 1 the minimum and 15 the maximum controlled variable represent. With an ever-widening range of steel grades, to be cast on a continuous caster, However, rule conditions of far more than 1:15 needed, as an ever-increasing Required bandwidth of the spray water flow to be set becomes.

To The prior art is, for example, in the continuous casting used regulations the controlled variable according to the following Principle influences. The control system receives the reference variable for the controlled variable and calculated from the feedback variable the so-called control deviation. According to the control deviation becomes the manipulated variable for the controlled system specified. The controlled system (valves, etc.) must have this value the given supply (hydraulic oil, electrical voltage, Water, air, etc.) implement and further process, the controlled system being due to the current state of the art Often unable to set the controlled variable a given supply quantity with appropriate accuracy to exactly regulate more than a limited relationship.

So will in the DE 2 344 438 Described a method for controlling the cooling of an emerging from a continuous casting strand with the ability to cool the strand in individual zones exactly to the extent that corresponds to the change in the heat transfer resistance with increasing solidification. For each zone, at the beginning of a casting process, the reference quantity of the groundwater quantity, which is based on the optimum amount of water, is set. During casting, by integrating the speed of the individual strand sections over the running time and simultaneously holding the time spent by a strand section in the cooling area time with a computer, the coolant amounts applied to the individual strand sections determined, compared with corresponding lead quantities and determines the remaining coolant amounts still applied to these strand sections , The setting is then made by adjustable slide or possibly by appropriate nozzle assembly, for example, the coolant quantity of all spray units is controlled together by a valve.

Furthermore, from the DE 103 21 791 A1 a method for controlling the temperature of a metal strip in a hot rolling finishing train, wherein a target function for actuators is formed by comparing a desired temperature profile with an actual temperature profile, the deviations detected arbitrarily positioned in the finishing line target specifications metrologically and mass flow (belt speed) and coolant flow are controlled on the one hand by pre-calculation and on the other hand online by solving a quadratic optimization problem with linear constraints.

Based on this described prior art, the object of the invention is to develop the existing control of various control variables in metallurgical plants so that even with commercial actuators with a small control range, the control system and a larger desired controlled variable always secured and reproducible with an optimal and improved control quality established.

The Asked task is procedurally with the characterizing features of claim 1 and device solved with the characterizing features of claim 6 characterized that for the realization of the largest possible control range used for the total supply quantity a controlled system in which when up-regulating the existing actuator with variable Controlled variable from a manipulated variable = x at least one further actuator with a freely selectable fixed set control variable in parallel is and from this manipulated variable = x the total supply from the resulting supply subsets combined is set.

For this is in the controlled system at least one actuator with variably adjustable Control variable, such as a control valve, with at least one actuator with adjustable controlled variable, For example, a switching valve connected in parallel. Latter actuator (and all others) are, for example, pure open-close actuators and act on the controlled variable with a fixed Value from the supply. The fixed value is adjustable and forms a part of the supply value. For setting the fixed control variable may be the passage parameters of the actuator such as Resistor, choke, line diameter changed and / or additional actuators are connected in parallel.

The desired controlled variable must be on this No longer just by an actuator with a limited control ratio be set, but is from a freely selectable Control value x combined with a fixed value set. This creates a significantly extended control range and a more precise and / or exact adjustability (or improved control quality) for the entire regulatory task. Prerequisite here is that the solid actuators a nearly constant and reproducible Own property in the control value output.

at Command value = x is not only high-level an actuator with permanently set controlled variable switched on, but at the same time the actuator with variable Re size so far down regulated that with newly set variable control variable plus the Fixed control variable of the control process also continued above the manipulated variable = x and the total supply is ensured. Due to existing Inertia during the shift (hysteresis) is when downshifting to consider the existing own defined hysteresis h. This happens in such a way that at the manipulated variable = x - h switching off the "constant" actuator takes place and from this value the "variable" actuator in Range 0 to x - h the regulation of the total supply quantity takes over again.

For the control down, the hysteresis h results in a smaller required control range S for the variable control variable actuator, which is determined as follows:
for x - h ≤ 50% S = x and
for x - h> 50%, S = x - h.

The overlap the manipulated variable of the "variable" actuator and all the parallel actuators is beyond the design defines the parallel branches and the "variable" actuator, so that the control system the desired controlled variable always secured and reproducible with an optimal and improved Setting quality.

• – Parallelschaltung von Regel- und Schaltvorrichtungen,
• – Parallelschaltung von mehreren Regelvorrichtungen,
• – Parallelschaltung von mehreren Schaltvorrichtungen (Kaskadierung),

wobei diese Regelungen mit Vorteil verwendet werden zur:

• – Regelung von Luft, Wasser, Öl als hydraulisches Medium wie beispielsweise HFC Ultra Safe, Quintolubric oder mineralisches Hydrauliköl, Öl als Schmierstoff oder ähnlichen Medien im Stahlwerk zur Erzeugung und Weiterverarbeitung von Flüssigstahl sowie flüssigen NE-Metallen,
• – Regelung von Luft, Wasser, Öl als hydraulisches Medium wie beispielsweise HFC Ultra Safe, Quintolubric oder mineralisches Hydrauliköl, Öl als Schmierstoff oder ähnlichen Medien einer Stranggießanlage zur Weiterverarbeitung von Flüssigstahl sowie flüssigen NE-Metallen zu Halbzeugen wie etwa Grammen, Dünnbrammen, Knüppeln, Blöcken, oder Ähnlichem,
• – Regelung von Luft, Wasser, Öl als hydraulisches Medium wie beispielsweise HFC Ultra Safe, Quintolubric oder mineralisches Hydrauliköl, Öl als Schmierstoff oder ähnlichen Medien eines Walzwerkes zur Weiterverarbeitung von Grammen, Dünnbrammen, Knüppeln, Blöcken, oder Ähnlichem,
• – Regelung von Luft, Wasser, Öl als hydraulisches Medium wie beispielsweise HFC Ultra Safe, Quintolubric oder mineralisches Hydrauliköl, Öl als Schmierstoff oder ähnlichen Medien für Nebeneinrichtungen eines Walzwerkes wie beispielsweise Haspel, Laminarkühlstrecke und Ähnlichem,
• – Regelung von Luft, Wasser, Öl als hydraulisches Medium wie beispielsweise HFC Ultra Safe, Quintolubric oder mineralisches Hydrauliköl, Öl als Schmierstoff oder ähnlichen Medien einer Bandbehandlungsanlage.

To achieve the required control ranges with a secure accuracy in metallurgical plants such as steel mills, continuous casting plants, rolling mills for example control of hydraulic, electrical and pneumatic devices (air, water, oil as a hydraulic medium such as HFC Ultra Safe, Quintolubric or mineral Hydraulic oil), oil as a lubricant, etc. According to the invention, the following combinations can be used within a controlled system:

• - parallel connection of control and switching devices,
• - parallel connection of several control devices,
• - parallel connection of several switching devices (cascading),

these arrangements are used to advantage for:

• - Control of air, water, oil as a hydraulic medium such as HFC Ultra Safe, Quintolubric or mineral hydraulic oil, oil as a lubricant or similar media in the steelworks for the production and processing of liquid steel and liquid non-ferrous metals,
• - Control of air, water, oil as a hydraulic medium such as HFC Ultra Safe, Quintolubric or mineral hydraulic oil, oil as a lubricant or similar media of a continuous casting plant for the further processing of liquid steel and liquid non-ferrous metals to semi-finished products such as logs, thin slabs, billets, blocks, or the like,
• - control of air, water, oil as a hydraulic medium such as HFC Ultra Safe, Quintolubric or mineral hydraulic oil, oil as a lubricant or similar media of a rolling mill for further processing of logs, thin slabs, billets, blocks, or the like,
• Control of air, water, oil as a hydraulic medium such as HFC Ultra Safe, Quintolubric or mineral hydraulic oil, oil as a lubricant or similar media for auxiliary equipment of a rolling mill such as reel, Laminarkühlstrecke and the like,
• - Control of air, water, oil as a hydraulic medium such as HFC Ultra Safe, Quintolubric or mineral hydraulic oil, oil as a lubricant or similar media of a belt treatment plant.

Further Advantages and details of the invention are given below in schematic drawings illustrated embodiments explained in more detail.

It demonstrate:

1 a control scheme according to the prior art,

2 a controlled system with three actuators connected in parallel,

3 Rule diagram for high rules,

4 Rule diagram for shutdown,

5 Control diagram for raising and lowering the constant actuator.

In the 1 A conventional control scheme is shown in the form of a flow chart in the prior art. The starting point here is the control system 3 into which a given reference variable 1 and a current feedback size 2 for calculating the manipulated variable 4 be entered. The manipulated variable 4 then puts in the actuator 5 with a certain control ratio the controlled variable 7 one, with the then from the supply 6 those in the process 10 required total supply amount is provided.

In order to increase the control conditions required for the regulation of a total supply quantity, according to the invention, the control system 3 calculated manipulated variable 4 in one in the 2 illustrated controlled system (actuator circuit) 8th fed. Within this plant 8th are in the illustrated embodiment, three actuators connected in parallel. Each of these actuators 5 _{1,2, n} is with the supply 6 connected and takes this one of its controlled variable 7 _{1,2, n} correspondingly large supply subset 6 _{1,2, n} , which adds up, the controlled variable 7 according to the process 10 to be supplied total supply quantity. The trained with adjustable control ratio actuator 5 ₁ acts on the total controlled variable 7 with a variable controlled variable 7 ₁ and the actuators connected in parallel 5 ₂ and 5 _n each with a fixed set control variable 7 ₂ and controlled variable 7 _n ,

In the 3 to 5 the operation of the method according to the invention is shown in the form of a control diagram with a manipulated variable range of up to 100%. The 3 shows the Hochregeln the controlled variable 7 with two actuators connected in parallel 5 ₁ and 5 ₂ , Plotted here is the desired controlled variable 7 in%, which should be fed to the process depending on the manipulated variable 4 in %. At the beginning of the control process, this value is determined solely by the actuator 5 ₁ adopted, so that the dashed lines of the controlled variable 7 ₁ parallel to the controlled variable 7 run. From a manipulated variable 4 = x (is about 65%) takes over the actuator connected in parallel 5 ₂ a permanently set controlled variable 7 ₂ so that the actuator 5 ₁ only to adjust reproducibly a range from 0 to this value x. For desired values greater than x, the actuator must 5 ₁ also only values of x minus fixed controlled variable 7 ₂ up to 100% minus permanently set controlled variable 7 ₂ set reproducibly, so can safely realize the large bandwidth of the entire control range despite a small control ratio. The adjustment of the actuator required at the value x 5 ₁ to a low value and then the set control variable 7 ₂ from the value x to the required controlled variable 7 to supplement is dashed lines.

In order to avoid constant switching on and off by the value around the switching point with the value x, all the actuators connected in parallel work with their own defined hysteresis h. Switching off therefore takes place at the value x - h. The actuator 5 ₁ therefore, it only has to take over a smaller control range here. In the 4 are the resulting conditions in the same way as in the 3 shown. The cut-off point x - h for the actuator 5 ₂ is now the amount of hysteresis h over the Zuschalt point x the 3 lower and here is about 54%, which is why accordingly later the actuator 5 ₁ must be high again at this shutdown.

In the 5 is only the connection 11 and the shutdown 12 of the actuator 5 ₂ represented according to the indicated directional arrows. The hysteresis h caused different on and off operations of 3 and 4 , as well as the location of the switching points x and x - h are highlighted by this presentation.

1

command variable

2

Feedback variable

3

control system

4

manipulated variable

5 _{1,2, n}

actuator

6

care

6 _{1,2, n}

Supply subset

7

controlled variable

7 _{1,2, n}

controlled variable (Part controlled variable)

8th

controlled system (Actuator circuit)

9

hysteresis

10

process

11

switch on

12

Switch off

H

hysteresis

S

range

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 2344438 [0005]
• - DE 10321791 A1 [0006]

Claims (16)

Method for controlling a wide variety of controlled variables ( 7 _{1 . 2} ) in metallurgical plants for the control of devices with a control system ( 3 ), from which the reference variable ( 1 ) and the return size ( 2 ) the calculation of an existing control deviation is carried out and a new control value ( 4 ) for the controlled system ( 8th ) is given, with which the actuator ( 5 ) the controlled variable ( 7 ) with which then the process ( 10 ) supply amount of a medium from the given supply ( 6 ) is regulated, characterized in that for the realization of the largest possible control range for the total supply amount, a controlled system ( 8th ) is used, when the up-regulation to the existing actuator ( 5 ₁ ) with variable control variable ( 7 ₁ ) from a manipulated variable ( 4 ) = x at least one further actuator ( 5 ₂ ) with a freely selectable, permanently set controlled variable ( 7 ₂ ) is connected in parallel and from this manipulated variable ( 4 ) = x the total supply quantity from the resulting supply subsets ( 6 _{1,2, n} ) is set in combination. Method according to Claim 1, characterized in that, in the case of a manipulated variable ( 4 ) = x during connection ( 11 ) of the actuator ( 5 ₂ ) at the same time the actuator ( 5 ₁ ) and with newly set variable control variable ( 7 ₁ ) continues the control process and ensures the required total supply. Method according to claim 1 or 2, characterized in that during sub-regulation ( 12 ) the existing own defined hysteresis (h) is taken into account in such a way that with a manipulated variable ( 4 ) = x - h the switch off ( 12 ) of the actuator ( 5 ₂ ) and from this value the actuator ( 5 ₁ ) in the range 0 to x - h the regulation of the total supply quantity takes over again. Method according to Claim 3, characterized in that the smaller control range (S) of the actuator (S) required by the hysteresis (h) 5 ₁ ) is determined as follows: for x - h ≤ 50%, S = x and for x - h> 50%, S = x - h A method according to claim 1, 2, 3 or 4, characterized in that for setting the constant controlled variable ( 7 ₂ ) the passage parameters of the actuator ( 5 ₂ ), such as resistance, throttle, line diameter changed and / or other actuators ( 5 _n ) are connected in parallel. Device for controlling a wide variety of controlled variables ( 7 _1.2 ) in metallurgical plants for the control of hydraulic, electrical and also pneumatic devices with a control system ( 3 ), from which the reference variable ( 1 ) and the return size ( 2 ) the calculation of an existing control deviation is carried out and a new control value ( 4 ) for the controlled system ( 8th ) is given, with which the actuator ( 5 _{1,2, n} ) the controlled variable ( 7 _{1,2, n} ) with which then the process ( 10 ) to be supplied total supply amount of, for example, hydraulic oil, water. Air, electrical voltage or current from the given supply ( 6 ), in particular for carrying out the method according to claim 1 to 5, characterized in that in the controlled system ( 8th ) at least one actuator ( 5 ₁ ) with variably adjustable controlled variable ( 7 ₁ ) with at least one actuator ( 5 ₂ ) with freely selectable, permanently set controlled variable ( 7 ₂ ) is connected in parallel. Device according to claim 6, characterized in that the actuator ( 5 ₁ ) a regulating device and the actuator ( 5 _2-n ) is a switching device. Apparatus according to claim 6 or 7, characterized in that at least two actuators ( 5 ₁ ) with variable control variable ( 7 ₁ ) are connected in parallel with each other. Apparatus according to claim 6 or 7, characterized in that at least two actuators ( 5 ₂ ) with permanently set controlled variable ( 72 ) are connected in parallel in the form of a cascade. Device according to claim 7 or 9, characterized in that the actuators ( 5 ₂ ) with permanently set controlled variable ( 7 ₂ ) are pure on-off or on-off actuators. Device according to claim 7, 8, 9 or 10, characterized in that the actuator ( 5 ₁ ) via a variable controlled variable ( 7 ₁ ), with at least the manipulated variable ( 4 ) to x% and then for values greater than x the manipulated variable from x to 100% minus fixed set control variable ( 7 ₂ ) be managed. Device according to one or more of the claims 7 to 11, characterized by their use for the regulation of Air, water, oil as a hydraulic medium such as HFC Ultra Safe, Quintolubric or mineral hydraulic oil, oil as a lubricant or similar media in the steelworks Production and processing of liquid steel as well as liquid non-ferrous metals. Device according to one or more of the claims 7 to 11, characterized by their use for the regulation of Air, water, oil as a hydraulic medium such as HFC Ultra Safe, Quintolubric or mineral hydraulic oil, oil as a lubricant or similar media of a continuous casting plant for further processing of liquid steel and liquid Non-ferrous metals to semi-finished products such as logs, thin slabs, Billets, blocks, or similar. Device according to one or more of the claims 7 to 11, characterized by their use for the regulation of Air, water, oil as a hydraulic medium such as HFC Ultra Safe, Quintolubric or mineral hydraulic oil, oil as a lubricant or similar media of a rolling mill for further processing of logs, thin slabs, billets, Blocks, or the like. Device according to one or more of the claims 7 to 11, characterized by their use for the regulation of Air, water, oil as a hydraulic medium such as HFC Ultra Safe, Quintolubric or mineral hydraulic oil, oil as a lubricant or similar media for ancillary equipment a rolling mill such as reel, Laminarkühlstrecke and similar. Device according to one or more of the claims 7 to 11, characterized by their use to the regulations of Air, water, oil as a hydraulic medium such as HFC Ultra Safe, Quintolubric or mineral hydraulic oil, oil as a lubricant or similar media of a belt treatment plant.