JP2018069260A - Molten metal surface level controller and molten metal surface level control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a molten metal surface level controller and a molten metal surface level control method capable of reducing influence by the change of actual operation characteristics in a control operation.SOLUTION: Provided is a molten metal surface level controller 20 comprising: a flow rate regulation part 18 regulating the amount of molten steel fed from a tundish 11 to a mold 13; a level sensor 19 detecting the molten metal surface level of the molten steel in the mold 13; and a control part 21 creating a control input for controlling the molten metal surface level based on the observed value of the molten metal surface level detected by the level sensor 19 and the objective value of the molten metal surface level and instructing the control input to the flow rate regulation part 18 as an operation command. The control part 21 includes: a linear control part 221 creating a linear control input signal; a disturbance suppression control part 222 creating a non-linear control input signal; and a control parameter change part changing the control parameters of the linear control part 221 and the disturbance suppression control part 222.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a molten metal level control apparatus and a molten metal level control method, and more particularly to a continuous casting machine that adjusts the amount of molten steel poured into the mold in order to control the molten metal level in the mold to a target value. The present invention relates to a hot water surface level control device and a hot water surface level control method.

  In the continuous casting process using a continuous casting machine, if the molten steel level in the mold of the continuous casting machine fluctuates, surface flaws and cracks in the slab may occur, breakouts that cause operational problems, etc. may occur. There is a case. Therefore, it is preferable that the molten steel level in the mold does not vary as much as possible. In response to this problem, for example, in Patent Document 1, the fluctuation of the molten metal level is suppressed with a desired characteristic such that the value based on the sum of the deviation from the target value of the molten metal level and the primary differential value of the deviation becomes zero. A hot water level control device comprising a possible controller is disclosed.

JP-A-5-277690

  However, in the control operation by the molten metal level control device disclosed in Patent Document 1, the desired characteristic itself such that the value based on the sum of the deviation from the target value of the molten metal level and the first derivative value of the deviation becomes zero. Remains constant without change. For this reason, for example, when the actual operation characteristics change due to various physical factors during the control operation, the control with the desired characteristics becomes unstable, and it may be difficult to suppress the fluctuation of the molten metal level.

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

In order to solve the above-mentioned problem, a hot water level control device according to an embodiment of the present invention includes:
A flow rate adjusting 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;
Based on the measured value of the hot water surface level detected by the level sensor and the target value of the hot water surface level, an operation amount for controlling the hot water surface level is generated, and the operation amount is used as an operation command. A control unit for instructing the flow rate adjustment unit,
The control unit includes a linear control unit that generates a linear control input signal, a disturbance suppression control unit that generates a nonlinear control input signal, and a control parameter change unit that changes a control parameter of linear control. .

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

In the hot water level control device according to an embodiment of the present invention,
The disturbance suppression control unit defines a switching line determined by a linear combination of signals of a deviation between the measured value of the molten metal level and the target value of the molten metal level, and a change amount of the deviation, and the switching line The nonlinear control input signal is generated by a sign of a value determined by substituting the deviation and a variation amount of the deviation into

In the hot water level control device according to an embodiment of the present invention,
The control parameter changing unit determines a reference model of a controlled object of the molten metal level control system, calculates a molten metal surface level estimated value using the reference model, and calculates the molten metal surface level estimated value and the molten metal surface level measured value. The control parameter of the linear control is changed by evaluating a change in the characteristics of the control target based on the difference and performing an operation of changing the control parameter.

  Further, it should be understood that one embodiment of the present invention can be realized as a method substantially conceived by the above-described apparatus, and these are also included in the scope of the present invention.

For example, a hot water surface level control method according to an embodiment of the present invention includes:
A molten metal surface provided with a flow rate adjusting unit for adjusting the amount of molten steel supplied from the tundish to the mold, a level sensor for detecting the molten metal level in the mold, and a control unit for outputting an operation command to the flow rate adjusting unit. A level control method using a level control device,
Generating a linear control input signal;
Generating a non-linear control input signal;
Changing the control parameters of the linear control;
Based on the measured value of the molten metal level detected by the level sensor and the target value of the molten metal level, the operation amount for controlling the molten metal surface level is generated by the changed control parameter, Outputting the operation amount as an operation command;
including.

  According to the hot water surface level control device and the hot water surface level control method according to the embodiment of the present invention, it is possible to reduce the influence due to the change in the actual operation characteristics during the control operation.

It is a figure which shows an example of schematic structure of the continuous casting machine which controls the hot_water | molten_metal surface level control with the hot_water | molten_metal 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 which shows schematic structure of the hot_water | molten_metal surface level control apparatus which concerns on one Embodiment of this 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. It is the schematic which shows an example of the relationship between the switching line (sigma) and the output signal _unl . It is a figure which shows the fluctuation | variation of the hot_water | molten_metal surface level at the time of controlling based on the control signal output from the control signal calculating part of FIG. It is a figure which shows typically the fall of a dummy bar. It is a block diagram which shows an example of the process in the control parameter change part which consists of the norm model calculation part of FIG. 4, a parameter calculation part, and a parameter update part. It is a figure which shows a 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 diagram illustrating an example of a schematic configuration of a continuous casting machine that controls a molten metal surface level by a molten metal surface level control device according to an embodiment of the present invention. The continuous casting machine 10 includes a tundish 11, a nozzle 12 formed so as to protrude downward from the bottom surface of the tundish 11, a mold (mold) 13 disposed below the tundish 11, and below the mold 13. A support roll 14 and a cooling water spray 15, a transport roll (pinch roll) 16, and a cutting machine 17. The support roll 14 forms a curved slab passage from the lower side of the mold 13 to the transport roll 16 disposed horizontally. The direction along the slab path from the mold 13 toward the transport roll 16 is referred to as the casting direction.

  The tundish 11 is an intermediate container that stores molten steel from a ladle. Molten steel stored in the tundish 11 is supplied to the mold 13 through a nozzle 12 having a constant inner diameter. The inlet 12a 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 of the nozzle inlet 12a. 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 of the inflow port 12a. In the present embodiment, the flow rate adjusting unit 18 will be described below as an example of a stepping cylinder that adjusts the opening degree of the inflow port 12a by being displaced in a direction (vertical direction) orthogonal to the inflow port 12a. .

  When the flow rate adjusting unit 18 is a stepping cylinder, when the stepping cylinder is moved away from the inlet 12a (displaced upward in FIG. 1), the opening degree of the inlet 12a is increased and supplied from the tundish 11 to the mold 13. The 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 becomes lower, 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 an unsolidified slab. The slab formed by the mold 13 is pulled out from the mold 13 along the casting direction. The mold 13 is provided with a level sensor 19 such as a vortex type level sensor. The level sensor 19 measures the level of molten steel in the mold 13.

  The slab pulled out from the mold 13 is supported by the support roll 14 and moves toward the transport roll 16 through the slab passage 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 pulled out and moved toward the transport roll 16.

  The cooling water spray 15 cools the slab by spraying water toward the slab passing through the slab passage. As the slab moves through the slab passage, the cooling by the cooling water spray 15 solidifies the unsolidified portion inside the slab. The slab is completely solidified before reaching the transport roll 16.

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

  At the start of the continuous casting process, a dummy bar is inserted from the lower end of the mold 13 to the transport roll 16 instead of the cast piece. The dummy bar blocks the slab 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 continuous casting is started by pulling the dummy bar to the cutting machine 17 side by the support roll 14.

  The dummy bar is configured by connecting a plurality of link members 31 with connecting pins 32 as shown in FIGS. 2A and 2B as examples of a side view and a plan view, respectively. In the dummy bar 30, the link members 31 adjacent to each other can rotate around the connecting pin 32.

  FIG. 3 is a functional block diagram showing a schematic configuration of the hot water level control device according to the present embodiment. The hot water 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 molten metal level control device 20 operates the stepping cylinder 18 based on the molten metal level of the 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 hot water level control device 20 including each functional block of the hot water level control device 20. The control unit 21 includes a processor such as a CPU (Central Processing Unit) that executes a program that defines a control procedure, and the program is stored in, for example, the storage unit 22 or an external storage medium.

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

  The memory | storage part 22 memorize | stores the various data for the hot-water surface level control apparatus 20 to use in hot-water surface level control. An example of data stored in the storage unit 22 will be described as appropriate together with details of the control performed by the control unit 21.

  Next, details of processing 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 molten metal level is indicated by y.

The control unit 21 repeatedly performs the process described below. Hereinafter, the process which the control part 21 performs at the time t is demonstrated. In each symbol used in the following description, when a process at time t is indicated, t is added as 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 mold surface level control system in the continuous casting machine 10 of FIG. FIG. 4 shows a model diagram used in the calculation in the control unit 21. 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 performs a predetermined calculation described later in each of these functional units.

Control signal computing unit 211, based on the deviation E _t of the molten metal surface level target value r in the mold 13, the actual molten steel surface level (measured value) in the mold 13, which is measured by the level sensor 19 and y _t, deviation E The operation amount u _t of the stepping cylinder 18 is determined so that _t becomes zero. The target value r of the hot water level is stored in advance in the storage unit 22, for example.

  The parts other than the functional parts in FIG. 4 are mathematical expressions showing the change in the molten steel surface level in the mold 13 determined by the molten steel flowing into the mold 13 by the operation of the stepping cylinder 18 and the drawing of the slab after initial solidification from the mold 13. It is a model. Here, “s” in the figure is a Laplace operator.

Various mathematical models (dynamic characteristic models) of the stepping cylinder 18 can be considered. In the example shown here, it is assumed that the operation is based on a pulse motor. In the example shown here, the operation amount u _t does not represent the entire opening, but is given as a change amount 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 calculation unit 211 to the flow rate adjustment unit 18 as an operation command. In the example shown here, the dynamic characteristic of the stepping cylinder 18 is modeled as a 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). Function g (x) to calculate the opening area based on the degree of opening X _t, is a function of the common flow setting determined using the amount of molten steel in the ladle (ladle) based on the opening area, those It is well known among contractors.

  Next, calculation processing in the control signal calculation unit 211, the normative 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 illustrating an example of processing in the control signal calculation unit 211. 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 an arbitrary control system such as output feedback or state feedback. Here, as an example, the linear control unit 221 is described as a feedback control system based on the molten metal surface level deviation (e _t ) and the difference (Δe _t ).

Here, in FIG. 5, it was described as a discrete time system. In an actual control system, assuming that the control cycle is Δt, an operation amount u _t is calculated every control cycle Δt, and is given as a command value to an actuator that operates 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 manipulated variable signal (non-linear input signal) _unl based on the 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 manipulated variable signal u _nl is generated based on the sign of a value determined by substituting the difference Δe _t . Next, the processing by the disturbance suppression control unit 222 will be specifically described.

Sliding mode control is a control system that achieves a control purpose by constraining a state to a hyperplane on a phase space that generates a slip state. The hyperplane is a switching hyperplane with an operation amount u _t and serves as a 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 ( It is represented as a switching line by 2).

FIG. 6 is a schematic diagram illustrating an example of the switching function σ on the phase plane. In the formula (2), _{P 1} and _{P 2,} for example, in the case where a linear control system is realized by PI (proportional integral) control _{is P 1 = P t I t t} S, the P 2 = _{P t} expressed. Here, _{P t} is a proportional gain: a (P gain proportional gain), _{I t} is an integral gain: a (I gain integral gain), _{t S} is the control cycle (Delta] t).

In the present embodiment, the control signal calculation unit 211 acquires the P gain P _t from the parameter update unit 214. For more information about the calculation of the P gain P _t by the parameter update unit 214 will be described later. Also, I gain _{I t} and control cycle _{t S} is, for example, stored in the storage unit 22.

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 This is represented by the sum of the manipulated variable signal (disturbance compensation signal) u _nl . Here, the manipulated variable signal u _l is expressed by the following equation (3).

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

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

  In Expression (4), if the reaching condition in the sliding mode control is satisfied, the switching line can be reached 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 due to the change in the value of σ, thereby increasing the load on the operation of the actuator. Therefore, the disturbance compensation signal u _nl may be determined by a saturation function as shown in the following equation (5).

In Expression (5), K is a gain coefficient of the disturbance suppression control unit 222. K _max is the maximum input value of the disturbance suppression control unit 222 and is stored in the storage unit 22 in advance, for example. 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 diagram showing the relationship between the value of the switching function σ and the disturbance compensation signal _unl . By determining the disturbance compensation signal u _nl by the saturation function in this way, the value of the disturbance compensation signal u _nl changes continuously even when the value of σ varies as shown in FIG. Therefore, even if the value of σ fluctuates, hunting in which the value of the disturbance compensation signal _unl oscillates hardly occurs, and smooth control input generation can be realized. That is, as in the present invention, the disturbance compensation signal u _{nl is set} to a saturation function as shown in Expression (5), so that the control signal calculation unit 211 can perform a smoothed control input.

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

The control signal calculation unit 211 outputs the control signal u _t calculated based on Expression (6) to the actuator that controls 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 12 a 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. FIG. 8A shows the fluctuation of the molten metal surface level based on the conventionally known general PI control, and FIG. 8B shows the control signal u _t output from the control signal calculation unit 211. The fluctuation of the hot water level when the control based on this is performed is shown. That is, the view shown in FIG. 8 (b), as compared to the diagram shown in FIG. 8 (a), shows the variation of the molten metal surface level the disturbance compensation signal u _nl is reflected for disturbance suppression. 8 (a) and 8 (b), an existing measurement graph shows an actual measurement value of fluctuations in the molten metal surface level when control is performed with existing facilities. 8 (a) and 8 (b), the simulation graph shows the fluctuation of the molten metal level derived when the disturbance measured in the existing measurement is inputted and the molten metal level control is simulated. .

  As can be understood from FIGS. 8A and 8B, when the hot water level control is performed by the hot water level control device 20 according to the present embodiment, compared to the case where the conventional PI control is performed, The fluctuation (runout width) is small with respect to the target value 40 mm of the hot water surface level. Thus, according to the hot_water | molten_metal surface level control apparatus 20 which concerns on the said embodiment, the fluctuation | variation of the hot_water | molten_metal surface level can be reduced compared with the control apparatus which performs the conventional PI control.

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, the hot water level control device 20 can generate the control signal u _t so as to suppress the influence of the disturbance by the disturbance compensation signal u _nl . Therefore, according to the hot water level control device 20, it is possible to reduce the influence of disturbance during the control operation.

  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 portion connected by the connecting pin 32 of the dummy bar 30 is detached from the slab passage, so-called sag has occurred. Even in this case, the influence of disturbance due to the drop can be reduced. Therefore, according to the hot water surface level control apparatus 20, the fluctuation | variation of the hot water surface level by 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 a change amount of the actual hot water surface level (actually measured hot water surface level change amount) and a calculated value of the hot water surface level change calculated by the control unit 21 (estimated hot water surface level change amount). Each calculation is performed in order to change the control parameter used in the control signal calculation unit 211. Details of processing by the control parameter changing unit will be described below with reference to FIG.

The parameter updating unit 214 updates a proportional coefficient when using PI control among control parameters. The parameter update unit 214 is shown as an example of the control parameter change. Based on the difference between the hot water surface level predicted by the reference model calculation unit 212 and the actual hot water surface level, Provide control parameters suitable for fluctuations. Here, in the block diagram of FIG. 10 are described as each process is discretely performed suit control period (t _s or Delta] t). Specifically, the normative model calculation unit 212, the parameter calculation unit 213, and the parameter update unit 214 determine the time based on the actually measured hot water surface level change amount and the hot water surface level change estimated value based on the control based on the control signal u _t at time t. A P gain P _{t + Δt} used in the control of _{t + Δt} is calculated.

The norm model calculation unit 212 determines a norm model to be controlled by the hot water surface level control system, calculates an estimated value of the hot water surface level using the norm model, and calculates an estimated value of the hot water surface level and an actual hot water surface level. The variation of the characteristics of the controlled object is evaluated based on the deviation from the measured value. Specifically, the reference model calculation unit 212, the control signal _{u t,} opening _{x t} of the stepping cylinder 18, pulling velocity _{V t} and molten metal surface level _{y t} of molten steel by the support roll 14 is input. Reference model calculation unit 212, based on the input bath level level y _t, and calculates the change amount [Delta] y _t of molten metal surface level. Variation [Delta] y _t of molten metal surface level is calculated as the difference between molten metal surface level y _t which is input, for example, the time stored in the storage unit 22 Delta] t before molten metal surface level _{y t-Δt, Δy t =} y _It is expressed as _t- y _t-Δt .

The normative model calculation unit 212 has a normative model that models the actual operation of the controlled object (models 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 the molten steel from the opening degree of the stepping cylinder 18 is a linear model, and is fixed as a linear coefficient N around a specific operating point.

Based on the reference model, the reference model calculation unit 212 calculates the difference between the absolute value of the estimated hot water level change amount and the absolute value of the measured hot water surface level change amount in the mold 13, thereby controlling the time t. The model deviation e _{M, t} in the used control characteristic is calculated. Model deviation e _{M, t,} when the measured melt surface level variation in the mold 13, y _t, is expressed by the following equation (7).

The model deviation e _{M, t} represents the difference between the estimated value of the molten metal level change amount and the actual measurement value, that is, the difference between the model assumed for control and the actual process. For example, if the amount of change in the measured hot water surface level is on average larger than the amount of change in the hot water surface level output from the reference model, the actual control gain needs to be increased because the plant gain of the reference model is small. Conversely, if the amount of change in the measured hot water level is smaller on average than the amount of change in the hot water level output from the reference model, 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. Further, the characteristics may change due to adhesion of the metal, etc., in order to cope with this. The model deviations e _{M and t} are input to the parameter calculation unit 213 by the reference model calculation unit 212.

The parameter calculation unit 213 and the parameter update unit 214 perform a calculation to change the control parameter, and change the control parameter for linear control. Specifically, the parameter calculation unit 213 calculates the adjustment amount ΔP _{B, t} as a proportional band to determine the P gain P _{t + Δt} in the process at time t + Δt based on the acquired model deviation e _{M, t} . Specifically, the parameter calculation unit 213 first calculates the average values (model average deviations) e _{sum and t} of the model deviations e _{M and t} in the processing of the 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 average deviation e _{sum, t} is expressed as the following equation (8).

The parameter calculation unit 213 determines the adjustment amount of the P gain based on the model average deviation e _{sum, t} . In the present embodiment, the parameter calculation unit 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 . Β _P1 and β _P2 are positive numbers that satisfy β _P1 <β _P2 . α _e1 , α _e2 , β _P1 and β _P2 are, for example, stored in the storage unit 22 in advance.

According to Expression (9), the parameter calculation unit 213 sets ΔP _{B, t} to −β _P2 , −β _P1 , 0, β _P1 , β _P2 according to the value of the model average deviation e _{sum, t.} Decide on. As described above, the parameter calculation unit 213 determines ΔP _{B, t} using the step function _, and outputs the same ΔP _{B, t} with respect to the model average deviation e _{sum, t} within a certain range. 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} is not 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 update unit 214.

Since the parameter calculation unit 213 determines ΔP _{B, t} based on the model average deviation e _{sum, t} that is the average value of the plurality of model deviations e _{M, t in} this way, for example, an error due to temporary erroneous detection or the like. It is easy to avoid the determination of ΔP _{B, t} .

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

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

In this way, the control unit 21 automatically determines the control characteristics based on the difference between the estimated hot water surface level change amount and the measured hot water surface level change amount. Thus, for example, in the continuous casting process, when the tip of the stepping cylinder 18 is worn or foreign matter adheres to the tip, the control unit 21 can perform control by reflecting this change in the control characteristics. it can. The control unit 21 operates the stepping cylinder 18 by using the control characteristic determined based on the P gain P _{t + Δt} calculated by the parameter update unit 214, so that the estimated molten metal level change amount and the actually measured molten metal surface level variation amount. The difference with can be reduced.

Specifically, the control unit 21 calculates a P gain based on the estimated molten metal level change amount and the measured molten metal surface level change amount, and determines the control characteristics of the flow rate adjusting unit 18 based on the calculated P gain. To 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 hot water level control device 20, it is possible to reduce the influence due to the change in characteristics during the control operation.

  FIG. 11 is a diagram illustrating an actual P gain change result, and is a diagram illustrating a result of performing the above-described control using actual equipment. In FIG. 11, the horizontal axis represents P gain, and the vertical axis represents the N number represented by the product of the number of continuous casting charges and the strand. In FIG. 11, the bar graph indicates the N number at each P gain, and the curve graph is obtained by approximating the bar graph with a curve. FIG. 11 shows the result of appropriately adjusting the change of the P gain in accordance with the change of the parameter (characteristic) to be controlled during operation, and it can be seen that it can cope with the actual operation characteristic.

  Although the present invention has been described based on the drawings and examples, it should be noted that those skilled in the art can easily make various modifications and corrections 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, the functions included in each means, each step, etc. can be rearranged so that there is no logical contradiction, and a plurality of means, steps, etc. can be combined or divided into one. .

DESCRIPTION OF SYMBOLS 10 Continuous casting machine 11 Tundish 12 Nozzle 12a Inlet 13 Mold 14 Support roll 15 Cooling water spray 16 Transfer roll 17 Cutting machine 18 Stepping cylinder (flow rate adjustment part)
DESCRIPTION OF SYMBOLS 19 Level sensor 20 Hot water level control apparatus 21 Control part 22 Memory | storage part 30 Dummy bar 31 Link member 32 Connecting pin 211 Control signal calculation part 212 Reference | standard model calculation part 213 Parameter calculation part 214 Parameter update part 221 Linear control part 222 Disturbance suppression control part

Claims (5)

A flow rate adjusting 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;
Based on the measured value of the hot water surface level detected by the level sensor and the target value of the hot water surface level, an operation amount for controlling the hot water surface level is generated, and the operation amount is used as an operation command. A control unit for instructing the flow rate adjustment unit,
The control unit includes a linear control unit that generates a linear control input signal, a disturbance suppression control unit that generates a nonlinear control input signal, and a control parameter change unit that changes control parameters of the linear control unit and the disturbance suppression control unit. And a hot water level control device.   The linear control unit is obtained by multiplying a deviation between the measured value of the molten metal level and the target value of the molten metal level by a predetermined coefficient, and by multiplying the variation of the deviation by a predetermined coefficient. The molten metal level control device according to claim 1, wherein the linear control input signal is calculated based on the signal. The disturbance suppression control unit defines a switching line determined by a linear combination of signals of a deviation between the measured value of the molten metal level and the target value of the molten metal level, and a change amount of the deviation, and the switching line The molten metal level control apparatus according to claim 1 or 2, wherein the non-linear control input signal is generated by a sign of a value determined by substituting the deviation and a change amount of the deviation into.   The control parameter changing unit determines a reference model of a control target of the molten metal level control system, calculates a molten metal level estimated value using the reference model, and the variation amount of the molten metal level estimated value and the molten metal level actual measurement The control parameter for the linear control is changed by performing an operation for evaluating a change in the characteristic of the control target based on a difference from a value fluctuation amount and changing the control parameter. The hot-water surface level control apparatus according to claim 3. A molten metal surface provided with a flow rate adjusting unit that adjusts the amount of molten steel supplied from the tundish to the mold, a level sensor that detects a molten metal level of the molten steel in the mold, and a control unit that outputs an operation command to the flow rate adjusting unit. A level control method using a level control device,
Generating a linear control input signal;
Generating a non-linear control input signal;
Changing the control parameters of the linear control;
Based on the measured value of the molten metal level detected by the level sensor and the target value of the molten metal level, the operation amount for controlling the molten metal surface level is generated by the changed control parameter, Outputting the operation amount as an operation command;
A hot water level control method.

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