JP6528756B2 - Hot water level control device and hot water level control method - Google Patents

Description

  The present invention relates to a level control apparatus and level control method, and more particularly, to a continuous casting machine for adjusting the pouring amount of molten steel to a mold in order to control the level of molten steel in the mold to a target value. The present invention relates to a mold level control apparatus and a level control method of the mold.

  In the continuous casting process using a continuous casting machine, if the surface level of the molten steel in the mold of the continuous casting machine fluctuates, surface defects and cracks of the slab occur and breakouts that cause troubles in operation occur. May. Therefore, it is preferable that the surface level of the molten steel in the mold does not fluctuate as much as possible. To solve this problem, for example, Patent Document 1 suppresses the fluctuation of the surface level with a desired characteristic such that the value based on the sum of the deviation of the surface level from the target value and the first derivative of the deviation becomes 0. A level control system is disclosed which comprises a possible controller.

Unexamined-Japanese-Patent No. 5-277690

  However, in the control operation by the surface level control device disclosed in Patent Document 1, the desired characteristic itself that the value based on the sum of the deviation of the surface level from the target value and the first derivative of the deviation is 0 Is constant without being changed. Therefore, for example, when the actual operation characteristic is changed due to various physical factors during the control operation, the control with the desired characteristic becomes unstable, and it may be difficult to suppress the fluctuation of the surface level.

  The present invention has been made in view of the above, and it is an object of the present invention to provide a level control device and level control method capable of reducing the influence of a change in actual operating characteristics during control operation.

In order to solve the above-mentioned subject, a hot water level control device concerning one embodiment of the present invention is:
A flow rate adjustment unit that adjusts the amount of molten steel supplied from the tundish to the mold;
A level sensor for detecting the level of molten steel in the mold;
An operation amount for controlling the surface level is generated based on an actual value of the surface level detected by the level sensor and a target value of the surface level, and the operation amount is used as an operation command. And a control unit for instructing the flow rate adjustment unit;
Wherein the control unit includes a linear control unit which generates a linear control input signal which is an operation amount signal of linear control systems, and the disturbance suppression control unit that generates a non-linear control input signal is a non-linear operation amount signal based on the sliding mode control And a control parameter change unit that changes a control parameter of the linear control.

In the level control device according to an embodiment of the present invention,
The linear control unit is obtained by multiplying the deviation between the measured value of the molten metal level and the target value of the molten metal level by a predetermined coefficient, and the variation of the deviation by a predetermined coefficient. And calculating the linear control input signal based on the signal.

In the level control device according to an embodiment of the present invention,
The disturbance suppression control unit defines a switching function which is determined by linear combination of respective signals of a deviation between an actual measurement value of the surface level and a target value of the surface level and a variation of the deviation, and the switching function The non-linear control input signal is generated according to the sign of the value determined by substituting the deviation and the amount of change of the deviation .

In the level control device according to an embodiment of the present invention,
The control parameter change unit determines a reference model of the control target of the hot water level control system, calculates the hot water level estimated value using the reference model, and calculates the hot water level estimated value and the hot water level actual measurement value. The control parameter of the linear control is changed by evaluating the fluctuation of the characteristic of the control target based on the difference and performing an operation of changing the control parameter.

  It should also be understood that one embodiment of the present invention may be implemented as a method substantially contemplating the above-described apparatus, and that these are also included within the scope of the present invention.

For example, the hot water level control method according to one embodiment of the present invention is
Hot water surface including a flow rate adjustment unit for adjusting the amount of molten steel supplied from the tundish to the mold, a level sensor for detecting the level of molten steel in the mold, and a control unit for outputting an operation command to the flow rate adjustment unit. A level control method using a level control device, comprising:
Generating a linear control input signal which is a manipulated variable signal of the linear control system ;
Generating a non-linear control input signal which is a non-linear manipulated variable signal based on sliding mode control ;
Changing control parameters of linear control;
An operation amount for controlling the surface level is generated based on the measured value of the surface level detected by the level sensor and the target value of the surface level according to the changed control parameter. Outputting the operation amount as an operation command;
including.

  According to the surface level control device and the surface level control method according to the embodiment of the present invention, it is possible to reduce the influence of the change of the actual operating characteristic during the control operation.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows an example of schematic structure of the continuous casting machine which controls a surface level by the surface level control apparatus which concerns on one Embodiment of this invention. It is a figure which shows an example of the structure of a dummy bar. It is a functional block diagram showing a schematic structure of a surface level control device concerning one embodiment of the present invention. It is a block diagram which shows an example of control in the continuous casting machine of FIG. 1 as a mathematical model. It is a block diagram which shows an example of the process in the control signal calculating part of FIG. It is the schematic which shows an example of switching function (sigma) on a phase plane. FIG. 7 is a schematic view showing an example of the relationship between a switching line σ and an output signal u _nl . It is a figure which shows the fluctuation | variation of a hot metal level in, when control is performed based on the control signal output from the control signal calculating part of FIG. It is a figure which shows the fall of a dummy bar typically. It is a block diagram which shows an example of a process in the control parameter change part which consists of a reference | standard model calculating part, a parameter calculating part, and a parameter update part of FIG. It is a figure which shows the P gain change result.

  Hereinafter, an embodiment according to the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a view showing an example of a schematic configuration of a continuous casting machine which controls the level of the molten metal level by the molten metal level control apparatus according to an embodiment of the present invention. The continuous casting machine 10 includes a tundish 11, a nozzle 12 formed to project downward from the bottom of the tundish 11, a mold 13 disposed below the tundish 11, and a lower part of the mold 13. The support roll 14 and the cooling water spray 15 which are disposed in the above, a transport roll (pinch roll) 16 and a cutting machine 17 are provided. The support roll 14 forms a curved slab passage from the lower side of the mold 13 to the horizontally disposed transfer roll 16. The direction along the cast strip passage from the mold 13 toward the transport roll 16 is referred to as the casting direction.

  Tundish 11 is an intermediate container for storing molten steel from a ladle. The molten steel stored in the tundish 11 is supplied to the mold 13 through the nozzle 12 having a constant inner diameter. The inlet 12 a of the nozzle 12 is provided with a flow rate adjusting unit 18 that adjusts the amount of molten steel flowing from the tundish 11 into the mold 13 by adjusting the opening degree of the nozzle inlet 12 a. That is, the flow rate adjusting unit 18 adjusts the amount of molten steel supplied from the tundish 11 to the mold 13 by adjusting the opening degree of the inlet 12 a. In the present embodiment, the flow rate adjustment unit 18 is described below as a stepping cylinder that adjusts the opening degree of the inflow port 12a by displacing in a direction (vertical direction) orthogonal to the inflow port 12a as an example. .

  When the flow rate adjusting unit 18 is a stepping cylinder, when the stepping cylinder is moved away from the inflow port 12a (displaced upward in FIG. 1), the opening degree of the inflow port 12a becomes high, and is supplied from the tundish 11 to the mold 13. Amount of molten steel increases. On the other hand, when the stepping cylinder is moved closer to the inflow port 12a (displaced downward in FIG. 1), the opening degree of the inflow port 12a decreases, and the amount of molten steel supplied from the tundish 11 to the mold 13 decreases.

  The molten steel supplied to the mold 13 is cooled on the inner wall surface of the mold 13 to form a non-solidified slab inside. The slab formed by the mold 13 is pulled out of the mold 13 along the pouring direction. The mold 13 is provided with a level sensor 19 such as an eddy current level sensor. Level sensor 19 measures the surface level of molten steel in mold 13.

  The slab pulled out of the mold 13 is supported by the support roll 14 and moves toward the transfer roll 16 through a slab path formed by the support roll 14. At least a part of the support roll 14 is constituted by a drive roll, and the slab is continuously drawn and moved toward the transport roll 16.

  The cooling water spray 15 cools the slab by injecting water toward the slab passing through the slab passage. As the slab travels through the slab channel, the cooling by the coolant spray 15 solidifies the unsolidified portion inside the slab. The slab solidifies completely before reaching the transport roll 16.

  The slab that has reached the transport roll 16 is transported by the transport roll 16 and cut by a cutter 17 such as a torch cutter, for example. The slab cut by the cutting machine 17 is conveyed, for example, to the rolling process which is the next process.

  At the start of the continuous casting process, a dummy bar is inserted in place of the slab from the lower end of the mold 13 to the transfer roll 16. The dummy bar closes the billet passage from the lower end of the mold 13 at the start of continuous casting. At the start of continuous casting, molten steel is supplied from the tundish 11 to the mold 13 with the dummy bars arranged. Then, the dummy bars are pulled out to the cutting machine 17 side by the support roll 14 to start continuous casting.

  For example, as shown in FIGS. 2A and 2B as an example of a side view and a plan view, respectively, the dummy bar is configured by connecting a plurality of link members 31 by a connecting pin 32. In the dummy bar 30, the link members 31 adjacent to each other are rotatable around the connection pin 32.

  FIG. 3 is a functional block diagram showing a schematic configuration of the level control apparatus according to the present embodiment. The molten metal level control device 20 includes a control unit 21, a storage unit 22, a flow rate adjustment unit (stepping cylinder) 18, and a level sensor 19. The level control device 20 operates the stepping cylinder 18 based on the level of molten steel in the mold 13 measured by the level sensor 19.

  The control unit 21 is a processor that controls and manages the entire surface level control device 20 including the functional blocks of the surface level control device 20. The control unit 21 is configured by a processor such as a CPU (Central Processing Unit) that executes a program that defines a control procedure, and the program is stored, for example, in the storage unit 22 or an external storage medium or the like.

  Control unit 21 generates a signal for operating stepping cylinder 18 based on the level of molten steel in mold 13. More specifically, the level control device 20 generates a control signal (operation command) to be sent to an actuator that operates the stepping cylinder 18. The details of the control (process) performed by the control unit 21 will be described later.

  The storage unit 22 stores various data to be used by the molten metal level control device 20 in molten metal level control. An example of data stored in the storage unit 22 will be described as appropriate together with the details of the control performed by the control unit 21.

  Next, details of the process executed by the control unit 21 will be described with reference to FIGS. 4 to 8. In the following description, the opening degree of the stepping cylinder 18 is indicated by x, and the surface level is indicated by y.

The control unit 21 repeatedly performs the process described below. Hereinafter, the process performed by the control unit 21 at time t will be described. In each symbol used in the following description, in order to indicate processing at time t, t is added with a subscript. For example, the opening and melt-surface level of the stepping cylinder 18 in the processing of time t, respectively expressed as x _t and y _t.

  FIG. 4 is a block diagram showing a level control system in a mold in the continuous casting machine 10 of FIG. FIG. 4 shows a model diagram used for the calculation in the control unit 21. As shown in FIG. In FIG. 4, the control system in the continuous casting machine 10 of FIG. 1 is modeled using a mathematical model in part. The control unit 21 includes a control signal calculation unit 211, a reference model calculation unit 212, a parameter calculation unit 213, and a parameter update unit 214, and these respective function units perform predetermined calculations described later.

The control signal calculation unit 211 calculates the deviation E _t based on the deviation E _t between the target surface level r in the mold 13 and the actual surface level (measured value) y _t in the mold 13 measured by the level sensor 19. _t defines the operation amount _{u t} of the stepping cylinder 18 so that 0. The target value r of the surface level is stored, for example, in the storage unit 22 in advance.

  Parts other than the respective functional parts in FIG. 4 are mathematical expressions indicating changes in molten steel level level in the mold 13 determined by pulling out from the mold 13 of molten steel flowing into the mold 13 by operation of the stepping cylinder 18 and the initial solidification. It is a model. Here, "s" in the figure is the Laplace operator.

Although various mathematical models (dynamic characteristic models) of the stepping cylinder 18 can be considered, in the example shown here, it is assumed that the pulse motor is operated as a base. In the example shown here, the operation amount u _t is not intended to represent the entire opening is given as the amount of change from the current position. Entire opening X _t thus is e as the integral value of the operation amount u _t. The operation amount u _t is output from the control signal computing unit 211 as an operation command to the flow rate adjusting unit 18. In the example shown here, the dynamic characteristics of the stepping cylinder 18 are modeled as first-order lag.

Relationship between the degree of opening _{X t} and the molten steel flow rate g _{(X t)} of the stepping cylinder 18 is given as a function g (x). The function g (x) is a function of a general flow rate setting determined by calculating the opening area based on the opening X _t and using the molten steel amount in the ladle based on the opening area. It is well known among traders.

  Next, calculation processing in the control signal calculation unit 211, the reference model calculation unit 212, the parameter calculation unit 213, and the parameter update unit 214 illustrated in FIG. 4 will be described.

  FIG. 5 is a block diagram showing an example of processing in the control signal operation unit 211. As shown in FIG. As shown in FIG. 5, the control signal calculation unit 211 includes a linear control unit 221 and a disturbance suppression control unit 222, and these control units 21 execute predetermined calculations.

The linear control unit 221 defines a linear control system, and can adopt any control system such as output feedback and state feedback. Here, as an example, the linear controller 221, described as a feedback control system based on the molten metal surface level difference (e _t) and the difference (Δe _t).

Here, in FIG. 5, it is described as a discrete time system. The actual control system, when the control period is Delta] t, is calculated by the operation amount u _t in each control cycle Delta] t, it is given as a command value to the actuator for operating the stepping cylinder 18. Further, the difference .DELTA.e _t of the molten metal surface level deviation e _t and molten metal surface level difference shown in FIG. 5 is described by the following formula (1), respectively.

Linear control unit 221, based on the difference .DELTA.e _t of molten metal surface level difference e _t and molten metal surface level difference, generates an operation amount signal (linear control input signal) u _l. Stroke signal u _l multiplies the signal obtained by multiplying a predetermined coefficient (for example, P ₁₎ to the molten metal surface level difference e _t, predetermined coefficient difference .DELTA.e _t of molten metal surface level difference (for example, P ₂₎ It is calculated based on the obtained signal.

The disturbance suppression control unit 222 sets a non-linear operation amount signal (non-linear input signal) u _nl based on sliding mode control. Disturbance suppression control section 222, defines the molten metal surface level difference e _t, the switching line defined by a linear combination of the difference .DELTA.e _t of molten metal surface level difference, the switching line, molten metal surface level difference e _t and bath level level deviation The operation amount signal u _nl is generated based on the sign of the value determined by substituting the difference Δe _t of The processing by the disturbance suppression control unit 222 will be specifically described next.

Sliding mode control is a control system that achieves a control purpose by constraining a state on a hyperplane on a phase space that generates a sliding state. Furthermore, the hyperplane is switched hyperplane manipulated variable u _t, the switching function. In the present embodiment, the switching function σ to be used when calculating the control signal to the stepping cylinder 18 to provide as an operation amount u _t of molten metal surface level control, as a linear combination of e _t and .DELTA.e _t, the following equation ( 2) is represented as a switching line.

FIG. 6 is a schematic view showing an example of the switching function σ on the phase plane. In equation (2), P ₁ and P ₂ are, for example, P ₁ = P _t I _t t _S when a linear control system is realized by PI (proportional integral) control, and P ₂ = P _t expressed. Here, P _t is a proportional gain (P gain: proportional gain), I _t is an integral gain (I gain: integral gain), and t _S is a control period (Δt).

In the present embodiment, the control signal calculation unit 211 acquires the P gain P _t from the parameter update unit 214. Details of the calculation of the P gain P _t by the parameter updating unit 214 will be described later. Further, the I gain I _t and the control period t _S are stored, for example, in the storage unit 22 in advance.

In the present embodiment, the control signal u _t, as described above, is calculated by the linear controller 221, and the operation amount signal u _l a linear control system, is calculated by the disturbance suppression control section 222, the sliding mode control It is represented by the sum with the operation amount signal (disturbance compensation signal) u _nl based on. Here, the operation amount signal u _l is expressed by the following equation (3).

  In Formula (4), P1 and P2 are as above-mentioned.

On the other hand, the disturbance compensation signal u _nl is a non-linear operation amount in sliding mode control, and is given by the following equation (4) according to the value of the switching function σ.

  In Expression (4), when the reaching condition in the sliding mode control is satisfied, it is possible to reach the switching line from a state away from the switching line.

Here, the disturbance compensation signal u _nl under the switching function σ as described above may change discontinuously by changing the positive or negative value of σ, and the load on the operation of the actuator may increase. Therefore, the disturbance compensation signal u _nl may be determined by a saturation function such as the following equation (5).

In equation (5), K is a gain coefficient of the disturbance suppression control unit 222. K _max is the maximum value of the input of the disturbance suppression control unit 222, and is stored, for example, in the storage unit 22 in advance. Further, σ ₁ and σ ₂ define a kind of boundary layer and are set appropriately. σ ₁ and σ ₂ satisfy σ ₁ > 0 and σ ₂ <0, respectively.

FIG. 7 is a schematic view showing the relationship between the value of the switching function σ and the disturbance compensation signal u _nl . By determining the disturbance compensation signal u _nl by the saturation function in this way, as shown in FIG. 7, the value of the disturbance compensation signal u _nl changes continuously even if the value of σ fluctuates. Therefore, even if the value of σ fluctuates, hunting in which the value of the disturbance compensation signal u _nl vibrates is less likely to occur, and smooth control input generation can be realized. That is, as in the present invention, the control signal operation unit 211 can perform smoothed control input by setting the disturbance compensation signal u _nl to a saturation function as expressed by equation (5).

In the present embodiment, the control signal u _t configured based on the switching function σ of Equation (2) is expressed as the following Equation (6).

Control signal computing unit 211, a control signal u _t calculated based on the equation (6), and outputs to the actuator for controlling the stepping cylinder 18. Actuator, based on the acquired control signal u _t, controls the stepping cylinder 18. By controlling the stepping cylinder 18, the opening degree of the nozzle inlet 12a is adjusted, and the amount of molten steel supplied from the tundish 11 to the mold 13 is controlled.

8, in the case of performing control on the basis of a control signal u _t output from the control signal calculation unit 211 of FIG. 4 is a diagram showing a variation of the molten metal surface level. 8 (a) is shows a variation of the molten metal surface level based on a standard PI control conventionally known, FIG. 8 (b), the control signal u _t output from the control signal calculation unit 211 It shows the fluctuation of the surface level when the control based on the above is performed. That is, the diagram shown in FIG. 8 (b) shows the fluctuation of the surface level on which the disturbance compensation signal u _nl for disturbance suppression is reflected, as compared with the diagram shown in FIG. 8 (a). In FIGS. 8 (a) and 8 (b), the graph of the existing measurement shows the measured value of the fluctuation of the surface level when the control is performed by the existing equipment. Further, in FIGS. 8A and 8B, the graph of the simulation shows the fluctuation of the surface level derived when the simulation of the surface level control is performed by inputting the disturbance observed in the existing measurement. .

  As can be understood from FIGS. 8A and 8B, when the control of the surface level by the surface level controller 20 according to the present embodiment is performed, as compared with the case where the conventional PI control is performed, The fluctuation (swing width) is smaller than the target value of 40 mm at the surface level. Thus, according to the molten metal level control apparatus 20 which concerns on the said embodiment, compared with the control apparatus which performs conventional PI control, the fluctuation | variation of a molten metal level can be reduced.

Thus, molten metal surface level control device 20 according to this embodiment, by having the disturbance suppression control section 222, based on the disturbance compensation signal u _nl, generates a control signal u _t. Therefore, molten metal surface level control device 20, the disturbance compensation signal u _nl, can generate a control signal u _t so as to suppress the influence of disturbance. Therefore, according to the level controller 20, the influence of disturbance during control operation can be reduced.

  For example, according to the molten metal level control device 20, at the initial stage of the continuous casting process, as shown in FIG. 9, a so-called depression occurs in which the portion connected by the connection pin 32 of the dummy bar 30 is separated from the slab passage. Even in this case, the influence of disturbance due to the drop can be reduced. Therefore, according to the molten metal level control device 20, the fluctuation of the molten metal level due to the disturbance can be suppressed.

  Next, processing by the reference model calculation unit 212, the parameter calculation unit 213, and the parameter update unit 214 of the control unit 21 will be described. The reference model calculation unit 212, the parameter calculation unit 213, and the parameter update unit 214 are collectively referred to as a "control parameter change unit". The control parameter changing unit is based on the actual amount of change in the surface level (the measured amount of surface level change) and the calculated value of the change in the surface level calculated by the control unit 21 (estimated amount of surface level change). Each operation is performed to change the control parameter used by the control signal operation unit 211. The details of the process by the control parameter changing unit will be described below with reference to FIG.

The parameter updating unit 214 is for updating a proportionality factor in the case of using PI control among control parameters. The parameter updating unit 214 is shown as an example of control parameter change, and based on the difference between the molten metal level predicted by the reference model calculation unit 212 and the actual molten metal level, according to the variation of the control object, Provide control parameters suitable for fluctuations. Here, in the block diagram of FIG. 10, each process is described as being discretely performed according to the control period (t _s or Δt). Specifically, the reference model calculation unit 212, the parameter calculating unit 213 and the parameter updating unit 214, based on the measured melt surface level variation and melt-surface level change estimate by the control based on the control signal u _t at time t, the time P gain P _{t + Δt} used in control of _{t + Δt} is calculated.

The reference model calculation unit 212 determines a reference model of a control target of the hot water level control system, calculates an estimated value of the hot water level using this reference model, and estimates the hot water level and the actual hot water level. By the deviation from the measured value of, the fluctuation of the property of the controlled object is evaluated. Specifically, the control signal u _t , the opening degree x _t of the stepping cylinder 18, the drawing speed V _t of molten steel by the support roll 14 and the surface level y _t are input to the reference model calculation unit 212. The reference model calculation unit 212 calculates a change amount Δy _t of the surface level based on the input surface level y _t . The change amount Δy _t of the surface level is calculated as a difference between the input surface level y _t and, for example, the surface level y _t −Δt before the time Δt stored in the storage unit 22, Δy _t = y _It is expressed as _{t −} y _{t − Δt} .

The reference model calculation unit 212 has a reference model obtained by modeling the operation of the actual control target (modeling of the dynamic characteristics of the stepping cylinder 18 and the process dynamic characteristics). Reference model calculation unit 212, based on the reference model, and calculates the variation of the molten metal surface level of the control signal u _t output from the control signal calculation section 211. In the reference model, the model for calculating the flow rate of molten steel from the opening of the stepping cylinder 18 is a linear model and is fixed as a linear coefficient N around a specific operating point.

The reference model calculation unit 212 controls the time t by calculating the difference between the absolute value of the estimated amount of level change and the absolute value of the actually measured amount of change in the mold 13 based on the reference model. The model deviation e _{M, t} in the used control characteristic is calculated. The model deviation e _{M, t} is expressed by the following equation (7), where y _t is the amount of change in the actual surface level of the mold 13.

The model deviation e _{M, t} represents the difference between the estimated value and the measured value of the level change amount of the molten metal, that is, the difference between the model assumed for control and the actual process. For example, if the amount of change in the measured level is on average larger than the amount of change in the level output from the reference model, the plant gain of the reference model is small, so the actual control gain needs to be increased. On the contrary, if the change amount of the actually measured surface level is smaller than the change amount of the surface level output by the reference model on average, the gain of the reference model is large, and therefore the control gain needs to be reduced. This is necessary because the opening of the stepping cylinder 18 has a non-linear characteristic, and the characteristic changes when the operating point is changed. In addition, the characteristics may change due to the adhesion of metal, etc., to cope with this. The model deviation e _{M, t} is input to the parameter calculator 213 by the reference model calculator 212.

The parameter operation unit 213 and the parameter update unit 214 perform an operation to change the control parameter, and change the control parameter of the linear control. Specifically, the parameter calculator 213 calculates the adjustment amount ΔP _{B, t} as a proportional band in order to determine the P gain P _{t + Δt} in the process of time t + Δt on the basis of the acquired model deviation e _{M, t} . Specifically, the parameter calculator 213 first calculates an average value (model average deviation) e _{sum, t} of model deviations e _{M, t} in processing of a predetermined period T from time T ₀ to time T _1. . T ₁ −T ₀ = T, and T ₁ is, for example, the current time t. The model mean deviation e _{sum, t} is expressed as the following equation (8).

The parameter calculator 213 determines the adjustment amount of P gain based on the model average deviation e _{sum, t} . In the present embodiment, the parameter calculator 213 determines ΔP _{B, t} by the step function shown in the following equation (9).

In Formula (9), α _e1 and α _e2 are positive numbers that satisfy α _e1 <α _e2 . Moreover, beta _P1 and beta _P2 are positive numbers satisfying the β _P1 <β _P2. α _e1 , α _e2 , β _P1 and β _P2 are stored, for example, in the storage unit 22 in advance.

According to the equation (9), the parameter calculator 213 determines ΔP _{B, t} as any one of −β _P2 , −β _P1 , 0, β _P1 and β _P2 according to the values of the model mean deviations e _{sum and t.} Decide on. As described above, the parameter operation unit 213 outputs the same ΔP _{B, t} with respect to the model average deviation e _{sum, t in} a predetermined range by determining ΔP _{B, t} using the step function. In the present embodiment, [Delta] P _B, the _t, has been described as determined using the step function, [Delta] P _{B, t,} for example a linear function or the like, may be determined using other functions. Further, ΔP _{B, t} may not be automatically determined by a function such as a step function, but may be received as a direct change amount of the proportional band by the operator and given to the parameter updating unit 214.

Since the parameter calculator 213 determines ΔP _{B, t} based on the model average deviation e _{sum, t} which is an average value of a plurality of model deviations e _{M, t} as described above, an error due to, for example, a temporary false detection or the like This makes it easy to avoid the determination of ΔP _{B, t} .

When the parameter calculation unit 213 determines ΔP _{B, t} , P gain P _{t + Δt} in the process of time _{t + Δt} is calculated using a P gain update equation shown in the following equation (10).

The P gain P _{t + Δt} in the process of the time t + Δt calculated by the control unit 21 is input to the control signal calculation unit 211 of FIG. 4 and used in the process of the time t + Δt. That is, in the process of time t + Δt, the control characteristic is determined based on P gain _{Pt + Δt} . When the P gain P _{t + Δt} is equal to the P gain P _t , the same control characteristic is used in the process of time t and the process of time t + Δt.

As described above, the control unit 21 automatically determines the control characteristic based on the difference between the estimated amount of change in molten metal level and the measured amount of change in molten metal level. Thereby, for example, when the tip of the stepping cylinder 18 is worn or foreign matter adheres to the tip in the continuous casting process, the control unit 21 may perform control by reflecting this change in the control characteristic. it can. The control unit 21 operates the stepping cylinder 18 using the control characteristic determined based on the P gain P _{t + Δt} calculated by the parameter updating unit 214, thereby estimating the amount of change in the level and the amount of change in the actually measured level. And the difference between

Specifically, control unit 21 calculates P gain based on the estimated amount of molten metal level change and the actual amount of molten metal level change, and determines the control characteristic of flow rate adjusting unit 18 based on the calculated P gain. Do. Then, the control unit 21 based on the determined control characteristic to generate a control signal u _t, thereby operating the flow rate adjusting unit 18 in the generated control signal u _t. Therefore, according to the molten metal level control device 20, the influence of the change of the characteristic during the control operation can be reduced.

  FIG. 11 is a diagram showing an actual P gain change result, and is a diagram showing a result of performing the above-described control using actual equipment. In FIG. 11, the horizontal axis shows P gain, and the vertical axis shows N number represented by the product of the number of charges of continuous casting and the strand. Further, in FIG. 11, the bar graph indicates the N number at each P gain, and the curve graph is a bar graph approximated by a curve. FIG. 11 shows that the P gain change is also appropriately adjusted according to the change of the control target parameter (characteristic) during operation, and it can be understood that it corresponds to the actual operating characteristic.

  Although the present invention has been described above based on the drawings and examples, it should be noted that those skilled in the art can easily make various changes and modifications based on the present disclosure. Therefore, it should be noted that these variations and modifications are included in the scope of the present invention. For example, each means, functions included in each step, etc. can be rearranged so as not to be logically contradictory, and it is possible to combine or divide a plurality of means, steps, etc. into one. .

10 Continuous Casting Machine 11 Tundish 12 Nozzle 12a Inlet 13 Mold 14 Support Roll 15 Cooling Water Spray 16 Transport Roll 17 Cutting Machine 18 Stepping Cylinder (Flow Control Part)
Reference Signs List 19 level sensor 20 level control device 21 control unit 22 storage unit 30 dummy bar 31 link member 32 connection pin 211 control signal operation unit 212 reference model operation unit 213 parameter operation unit 214 parameter update unit 221 linear control unit 222 disturbance control unit

Claims (5)

A flow rate adjustment unit that adjusts the amount of molten steel supplied from the tundish to the mold;
A level sensor for detecting the level of molten steel in the mold;
An operation amount for controlling the surface level is generated based on an actual value of the surface level detected by the level sensor and a target value of the surface level, and the operation amount is used as an operation command. And a control unit for instructing the flow rate adjustment unit;
Wherein the control unit includes a linear control unit which generates a linear control input signal which is an operation amount signal of linear control systems, and the disturbance suppression control unit that generates a non-linear control input signal is a non-linear operation amount signal based on the sliding mode control And a control parameter change unit configured to change control parameters of the linear control unit and the disturbance suppression control unit.   The linear control unit is obtained by multiplying the deviation between the measured value of the molten metal level and the target value of the molten metal level by a predetermined coefficient, and the variation of the deviation by a predetermined coefficient. The level control system according to claim 1, wherein the linear control input signal is calculated based on a signal. The disturbance suppression control unit defines a switching function which is determined by linear combination of respective signals of a deviation between an actual measurement value of the surface level and a target value of the surface level and a variation of the deviation, and the switching function The level control system according to claim 1 or 2, wherein the nonlinear control input signal is generated by a sign of a value determined by substituting the deviation and a variation of the deviation.   The control parameter change unit determines a reference model of the control target of the hot water level control system, calculates the hot water level estimation value using the reference model, and measures the fluctuation amount of the hot water level estimation value and the hot water level measurement The control parameter of the linear control is changed by evaluating the fluctuation of the characteristic of the controlled object based on the difference between the value and the fluctuation amount of the value and performing an operation of changing the control parameter. The level control device according to any one of claims 3 to 10. Hot water surface including a flow rate adjustment unit for adjusting the amount of molten steel supplied from the tundish to the mold, a level sensor for detecting the level of molten steel in the mold, and a control unit for outputting an operation command to the flow rate adjustment unit. A level control method using a level control device, comprising:
Generating a linear control input signal which is a manipulated variable signal of the linear control system ;
Generating a non-linear control input signal which is a non-linear manipulated variable signal based on sliding mode control ;
Changing control parameters of linear control;
An operation amount for controlling the surface level is generated based on the measured value of the surface level detected by the level sensor and the target value of the surface level according to the changed control parameter. Outputting the operation amount as an operation command;
Surface level control method including.

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