阅读说明：本技术 基于模型预测控制的粉料混合水分控制系统 (Powder mix moisture control system based on Model Predictive Control ) 是由 许向阳 段居方 王军 于 2019-09-20 设计创作，主要内容包括：本专利名称为“基于模型预测控制的粉料混合水分控制系统”,属于过程控制领域。在生产活动中,常常会涉及对粉料加水混合的工艺,这类系统因其加水时刻与水分测量时刻间往往需要较长时间进行混合,故该问题的一大特点是具有较大的时延。为此本专利提出以预测控制为主要技术手段,通过实际粉料投放量、加水量实际测量值来预测加水点的水分,并通过内外环的PID控制器调节加水量从而达到在具有较大时延的系统中精确控制加水量的功能。本发明能达到的效果包括：在具有大时延的粉料混合系统中,提供一种能对水分精确控制的方法,使控制精度相比人工设定加水量更高,并且做到提高产品品质,减少浪费。(This patent is entitled " the powder mix moisture control system based on Model Predictive Control ", belongs to process control field.In production activity, the technique that can be usually related to adding powder water to mix, this kind of system generally requires the long period and is mixed because it adds between water moment and moisture measurement moment, therefore the one of the problem big feature is that have biggish time delay.This patent is proposed using PREDICTIVE CONTROL as technical way thus, the moisture of filling up area is predicted by practical powder injected volume, amount of water actual measured value, and amount of water is adjusted to reach the function of accurately controlling amount of water in having the system compared with long time delay by the PID controller of inner and outer ring.The present invention can achieve the effect that include: in the powder hybrid system with long time delay, provide it is a kind of can make to control precision higher compared to artificial setting amount of water to the method that moisture accurately controls, and accomplish to improve product quality, reduce waste.)

1. the powder mix moisture control system based on Model Predictive Control, which is characterized in that using PREDICTIVE CONTROL as major technique Means are predicted the moisture of filling up area by practical powder injected volume, amount of water actual measured value, and pass through inside and outside ring controller Amount of water is adjusted to reach the function of accurately controlling amount of water in there is the system compared with long time delay.

Technical field

The present invention relates to a kind of control systems for powder mixed process moisture size.Using PREDICTIVE CONTROL as major technique Means are predicted the moisture of filling up area by practical powder injected volume, amount of water actual measured value, and pass through inside and outside ring controller Amount of water is adjusted to reach the function of accurately controlling amount of water in there is the system compared with long time delay.The invention patent belonged to Process control field.

Background technique

In production activity, the technique that can usually be related to adding powder water to mix.Mixing in this kind of technique, after adding water Whether object moisture content accurately decides that can subsequent production link go on smoothly；Also, this kind of system adds the water moment because of it Generally requiring the long period between the moisture measurement moment is mixed, therefore the one of the problem big feature is that have biggish time delay, This time delay is very unfavorable to the control of moisture, directly controls and is extremely difficult to ideal control effect.

Such as Fig. 1, by steel plant to miberal powder plus for water mixing, miberal powder adds and can enter roller after water and mix, amount of water Size determine the moisture content of material after mixing, and the height of moisture content decides product quality in subsequent ironmaking processes Height, therefore moisture content control precision is particularly significant, that is, the control of amount of water is particularly significant.And from before roller plus Moisture measurement point after water spot to roller out will pass through about 130 seconds altogether, generate huge time delay.Due at this 130 seconds In the process, miberal powder situation may fluctuated all at any time, and the adjustment effect of water needs can just learn effect after 130 seconds, This necessarily causes runoff investigation very poor to the control effect of moisture content after mixing, easily causes moisture and controls not up to standard and cause Subsequent product quality is not up to standard.

In this regard, the invention patent proposes the powder mix moisture control system using PREDICTIVE CONTROL as core, prediction is utilized The inner loop control circuit that model is formed fast and effectively inhibits main interference, thus in the system with long time delay Accurate control amount of water, makes powder add the mixed moisture value of water fuctuation within a narrow range near setting value, reaches more precise control Effect.

Summary of the invention

It is an object of the invention to solve in the mixing of current powder moisture content accurately to control due to being difficult to there are long time delay The problem of processed, proposes the moisture control subsystem based on PREDICTIVE CONTROL.In the control system, read from industrial sensor first The measured value of the measured value plus water water that enter powder material weighing to be mixed waits until in controller, calculates moisture by prediction model Predicted value, realized by inner loop control device and main interference fast and effectively inhibited；It is outer by being carried out to moisture predicted value again Ring compensation control, final realize overcome time delay in long time delay system, improve the effect of moisture control precision.

The beneficial effect that the present invention can obtain include: in the powder hybrid system with long time delay, by prediction model, The cascade control system with inner and outer ring control loop is constructed, a kind of side that can be improved moisture content and accurately control finally is provided Method overcomes long time delay to influence control bring, to reach raising product quality, reduces the effect of waste.

Detailed description of the invention

Fig. 1: the mixing apparatus of powdery row material schematic diagram in steel plant

Fig. 2: control system block diagram

Fig. 3: control system equivalent diagram

Specific embodiment

The core idea of the invention is as follows Model Predictive Control can be pre- in real time online that is, according to the mathematical modeling of mixed process The moisture value in the mixed material of filling up area position is surveyed, and moisture content is controlled by the adjusting of amount of water.Due to coming to control It says, the moisture to filling up area position is predicted as most fastly, therefore using the point as future position, and moisture content control is maximally efficient.It It is finely adjusted again by the practical moisture measurement value of outer ring afterwards, practical mixing water score value is made to reach setting moisture value.Control system Block diagram as shown in Fig. 2, each variable, module in system block diagram illustrated in table 1.

1 control system block diagram explanation of table

Variable, module or transmission function	Explanation
		RD	The moisture content of setting
u	Add water management amount
		GP1~GP4	Real process
G1~G4	Mathematical prediction model
		DP	Predict moisture content
Dd	Moisture measurement value
		Ws	The practical inventory of powder
Wd	Powder feeds intake measurement
		Fd	Measuring water flow value

1) prediction model

Assuming that the water content of original powder is certain, the water content of powder can not be considered in this way in prediction model.

If the practical inventory of powder is W_s(t) (Kg/h), the measured value of powder material weighing are W_d(t) (Kg/h), powder to mixing The estimated value of point is W_p(t) (Kg/h), then:

Wherein δ W (s) is noise, T₁For the time constant of weighing instrument.

(note: X (s) is the Laplace transformation of signal X (t).)

Wherein est { } is estimation, T₂For the time constant of powder to mixing point, τ₁For powder to mixing point pure time delay when Between.

If the measured value of water is F_d(t) (Kg/h), it is assumed that measure of water accurately without time delay, estimate by the prediction of water to mixing point It is calculated as F_p(t) (Kg/h), then:

Wherein τ₂The pure time delay time of mixing point is arrived for filling up area (namely measure of water point).

Due to for control, the moisture to filling up area position be predicted as it is most fast, therefore using the point as future position, then plus The predicted value of water spot moisture may be expressed as:

Figure it is seen that the moisture content of filling up area is predicted by the measurement to powder inventory and amount of water, etc. Valence carries out the direct measurement of moisture content in Fig. 3 in filling up area, and the transmission function of equal value (model) of the Measurement channel has very Small time delay；Meanwhile the interference such as water flow fluctuation and the fluctuation of powder inventory caused by water pressure fluctuations etc., it is predicting It can be embodied in real time in model, therefore in 1 circuit of controller, these disturbing factors can obtain quickly effectively inhibiting, from It and is where entire control loop realizes that high-precision brings condition and the core of this patent.

2) control loop designs

Inner and outer ring dual controller, which is used, such as Fig. 2, in this patent forms serials control circuit.The controller action of inner ring compared with By force, for quickly being adjusted according to predicted value, main from water flow fluctuation and the fluctuation of powder inventory etc. in inner ring Interference is quickly and effectively inhibited；The controller action of outer ring is weaker, is finely adjusted for the deviation to prediction model.

In the control loop of inner and outer ring, it is all provided with the automatic no-harass switch method of hand.Inner ring hand automatically switch for Producing can automatically control in unbroken situation taking human as adjusting amount of water, and from manual operation no-harass switch to system.For Hand automatically switches, and when being in manual mode, output quantity U is enabled directly to track the amount of water manually set；Outer ring hand automatically switches It is set for manual adjustment inner ring, i.e., inner ring moisture content is set, after inner ring is steady, from manual operation no-harass switch to system It automatically controls, realizes that entire control loop reaches auto state.The automatic no-harass switch method of hand is mainly used for driving and parking process Smooth transition.