Donetsk National Technical University
Murashov Evgeniy Alexandrovich

FCITA group AT-01

e-mail: falling__angel@mail.ru

Theme of master's work:

"Coordinating SCADA-control system of CCM"

 The scientific chief:

Sukov Sergey Feliksovich

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Master thesis

Content

Introduction

Development of automation in a national economy and in all spheres of human activity goes on a way of gradual increase in a complex of machines and the units connected one or several interdependent control systems. In a basis of any control system the information processes connected to gathering of the information, its primary processing, transfer on different levels of system, storage, distribution and display, and also performance of commands of management lay. Creation of the information monitoring system and management of CCM, allows: to increase productivity of installation, to raise an output of suitable metal, to improve quality of an ingot, to reduce number of emergency operation of work and to raise serviceability of all object.

The most sensitive part of the continuous casting plant is the mold area. It is here that the liquid steel must form a solid shell before it is drawn into the casting machine. During the growth of the shell, problems such as sticker and air gap can occur, which lead to a breakout when the defective zone leaves the mold. The result is production downtime and expensive repairs. System helps avoid these problems by indicating a sticker or air gap in a timely manner, enabling reduction of the casting speed and correction of the defective zone.

The description of technological object

1. The technological circuit of object

The technological circuit of object is submitted in figure 1.

fig 1 The technological circuit of object
Figure 1 The technological circuit of object

The principle of work of CCM will consist in the following:

The steel casting ladle in capacity of 140 tons moves on CCM. Flood is carried out through an intermediate ladle, preliminary heated to temperature of 1000-1100 degrees in a crystallizer. Before the beginning of pouring in a cavity of a crystallizer the combined priming is entered. The priming represents an empty box, from sheet steel which cross-section corresponds to a structure of a crystallizer. In the beginning of process of moulding the priming forms a bottom of a crystallizer. The bottom end of a crystallizer to be in rollers pulling of cage. Acting metal, hardens at walls of a crystallizer and a priming. At achievement of the established level of metal in a crystallizer, there is an inclusion pulling of cage which extends a priming together with an ingot which crystallizes. The ingot which has left a crystallizer has viscous, practically liquid core, therefore an ingot located in a zone of secondary cooling (ZSC). For elimination of possible sticking and breakage of the stiffened metal on a working surface of a crystallizer greasing (slag mixes) moves, and the crystallizer to be actuated. After zone ZSC, the slab which has cooled down on all parameter, moves to a gas cutting torch. The cut slabs are accepted and are transferred on roller machine.

2. Management of CCM

Control system of CCM is distributed on 6 subsystems of management. The brief characteristic of everyone:

  1. Regulation of a level of metal in an intermediate ladle. Management to be reduced to management of a stopper on a steel casting ladle.
  2. Regulation of a level of metal in a crystallizer and a thermal mode of a crystallizer. For management of cooling is used the parity “ temperature drop - the charge of water ”.
  3. System of shake a crystallizer.
  4. Management of a thermal mode in section of zones of secondary cooling.
  5. Regulation of speed pulling cage.
  6. Regulation of the charge of gas for system of division of an ingot for measured lengths.

Information streams at management of CCM

1. Structure of problems management

The structure of problems for management and control of CCM is shared on two groups: information problems and problems of management.

Problems of management share on tasks of management installation in a normal mode and in emergency operation. Management in a normal mode means: start-up of installation, a stop of installation, maintenance of work of installation in the set mode, regulation of parameters, correction of parameters, forecasting of situations, management of executive mechanisms. Management in emergency operation includes: elimination of an emergency, an emergency stop, switching of executive mechanisms.

Information problems can be divided into three subgroups:

  • problems which provide with the information algorithms of management of technological installation;
  • problems which provide with the information of the operator of installation, the dispatcher and algorithms of the top level of a control system;
  • problems which provide functioning a complex of means.

The basic functions of management ACS of TP of continuous moulding of preparations:

Management in sizes

Management of processes
  • starting mode of CCM;
  • mode of secondary cooling of an ingot;
  • drive pulling of cage;
  • divisions of an ingot into measured lengths;
  • optimum mode of the ending of casting with the purpose of reduction of waste products.

2. Information and managing functions

For management of technological process of continuous moulding of preparations it is necessary to provide an opportunity of switching of control modes depending on a situation, namely: an automatic mode and a manual mode. At an automatic mode a course of process the industrial controller operates according to algorithm which in it is programmed. In a manual mode process the operator from the camera board with use SCADA - systems operates. The information on a condition of object is necessary for management of installation. Thus between the first level of management and top such streams of the information circulate:

  • temperature of liquid steel in a steel casting ladle;
  • temperature of liquid steel in an intermediate ladle;
  • weight of steel in an intermediate ladle;
  • weight of steel in сталеразливочном a ladle;
  • level of metal in a crystallizer;
  • effort of pulling an ingot from a crystallizer;
  • speed of pulling an ingot;
  • the charge and pressure of cooling water upon a crystallizer;
  • difference of temperatures of cooling water on a crystallizer;
  • the charge of technological greasing on a crystallizer;
  • the charge and pressure of water on section of secondary cooling;
  • temperature of a surface of an ingot.

Consideration existing SCADA systems

The SCADA-system is a Supervisory Control And Data Acquisition. It is set of devices of management and monitoring, and also a way of interaction with technological object. For today as this term understand a set program and hardware, for realization of camera workplaces.

At creation of information system are united in one functional unit a plenty of local subsystems which frequently have various program interfaces. It considerably complicates a problem of the coordination of such subsystems and reduces speed of system as a whole. Connection of local functional units with an identical program platform therefore is expedient. SCADA - system realizes this approach, therefore its application now everywhere and actually. Also directly the hardware is developed for a software package that allows to create information system more cheaply and with the minimal expenses of time.

In the today's market of the software plenty SCADA - systems is submitted. Most popular of them are submitted in the table.

SCADA- systems Firm the manufacturer Country
LabVIEW National Instruments USA
WinCC Siemens Germany
Trace Mode AdAstra Russia
RSView Rockwell Software Inc USA

Anyone SCADA - system should provide a number of functionalities. We list the basic opportunities and means which are inherent in all systems and differ only technical features of realization:

  • Automatic development which enables creations of the software without real programming;
  • Means of gathering of the primary information from devices of the bottom level;
  • Control facilities and registration of signals about emergencies;
  • Means of storage of the information with an opportunity of its subsequent processing;
  • Means of processing of the primary information;
  • Means of visualization of processes.

The listed opportunities of such systems substantially determine cost and terms of creation of the software, and also times of recovery of outlay.

One of factors which influences a choice of similar system is a program hardware platform on which it is realized SCADA - system. The analysis of transfer of such platforms is necessary, because the answer to a question of distribution SCADA depends on it - systems on existing numerical means. It is meant, that with the applied program developed in one operational environment, can be carried out in any other operational environment which supports given SCADA - a package. Significant majority SCADA - systems are realized on platform Microsoft Windows.

Such system should have means of network support. It is obvious, that for effective functioning in different industrial SCADA environment - the system should provide a high level of network service, that is it should support work in standard networks (Ethernet, ArcNet) and reports (TCP/IP, NETBIOS).

For designing systems of automation are important the opportunities of the graphic interface. In each such system there is a graphic object-oriented editor with a set of animation functions.

One of factors determining a choice of SCADA-system is technical support of firm of the manufacturer. For today leading firms manufacturers of the given systems provide various enough support of the users. It will consist in carrying out of regular training courses, maintenance of service, the organization of a "hot" line and the help in the decision of the problems connected to individual requirements of the customer of system, and also information support with the help of global network Internet.

The most popular SCADA - systems own the listed functionalities. The technology of programming is close to intuitive understanding of the automatic process that makes these products easy in development and accessible for a wide range of users. All systems can be counted open which have the open report for development of own drivers. All of them have the advanced network support, an opportunity of inclusion Active-X of objects.

Also it is necessary to note, that construction of system on basis SCADA - a package sharply reduces a set of necessary knowledge in the field of classical programming, allowing to concentrate efforts on development of knowledge in applied area. Thus, the choice of such system is made from criterion of quality of technical support, quality of training of users and quality of additional services on development and introduction of a final control system.

Choice a SCADA - package

To SCADA - system made the following demands:

  • Quality of the documentation;
  • Technical support;
  • Scale - an opportunity of creation of projects of different scale;
  • Openness of systems - an opportunity of the coordination of the given system with the equipment of other firms of manufacturers;
  • Full functionality and reliability;
  • System effectiveness. It means, that functions of input-output, archiving and visualization should have necessary functionality and speed;
  • The price.

As an actual problem is development of ACS of TP CCM on domestic hardware base it has been chosen SCADA - system of Russian firm AdAstra Trace Mode. Realization of information system on base Trace Mode allows to lower expenses of means on designing, assembly and diagnostics of system. This package meets above to the listed requirements and has a number of convenient functionalities.

Choice of topology and the interface of a network

For projected information system it is necessary to choose topology and the interface of a network. As it is necessary to receive the information from any information unit at any moment is chosen the highway with network Ethernet. In figure 2 is submitted the structure of a network.

fig2 Structure of a network
Figure 2 Structure of a network

Speed of transfer of the chosen interface 10 Mb/s. As work of a network in an excited environment as connecting cables at the bottom level of management the shielded twisted pair gets out. On the second and above levels of management it is possible to apply a simple twisted pair.

System of forecasting a breaks

The greatest problem in the mold is a sticker, which is caused by locally high friction between the strand shell and the mold. The strand shell sticks to the mold copper plate, and, by drawing out the strand, the shell is stressed and breaks, so that liquid steel splashes onto the copper plate. Another problem involves air gaps (cracks) between the strand shell and the mold plate, which are often formed at the edge between narrow and broad faces Due to the low thermal conductivity of the air, the shell cannot be cooled adequately, and it remains too thin. On the animated figure 3 ( developed by master of DonNTU Murashov E.A., 15 frame, 110кб) is presented a process of break of liquid metal on a wall of a crystallizer and is submitted to corresponding it dynamics of change of temperature.

figure 3 Emergency of break of liquid metal
Figure 3 Emergency of break of liquid metal

Evaluation of the temperature patterns and prediction of breakouts are performed by the advanced PLC running the open visualization system. Thermoelements measure the temperatures in the upper mold area and transfer them to the systems of prediction, which detects temperature patterns for both sticker and air gaps. The values for temperature and change of temperature of each sensor serve as inputs for evaluation by fuzzy logic of the probability of a breakout. A simple yet smart algorithm gives the system a very fast reaction time. Since the system must detect break-outs reliably, while avoiding expensive false alarms. restrictions are placed on the system that include:

  • Close monitoring of the casting speed;
  • Level of metal in a crystallizer;
  • Automatic deselection of defect thermoelements.

The conclusion

Acquaintance with object of management is lead and the information monitoring system and managements of CCM is designed. For the developed system the structure of problems of the control and management, structure of information streams is determined. The analysis existing SCADA - systems is lead and is chosen Trace Mode as it has all necessary functionalities and is much cheaper in realization and diagnostics than foreign analogues. It successfully answers a number of the requirements put to it. The local network for automatic control system of technological process of CCM is designed. The topology of a network represents a highway that is more effective and it is reliable, as interrogation of gauges can be carried out during the casual moments of time. As the interface of a network it is chosen Ethernet with speed of transfer 10 Mb / s. For development of the software of system it is necessary to receive mathematical model of object. After that will be lead imitating modelling.

The list of the literature

  1. Анюхин М.Н., Полюляшный А.С., Новиков О.И., Яршин Ю.В. Журнал "Сталь". Автоматическое поддержание уровня металла в кристаллизаторе МНЛЗ. №9, 1995 г., стр. 24-25.
  2. Каганов В.Ю. Машина непрерывного литья заготовок. М., 1990 г., 250 стр.
  3. Нисковских В.М., Карлинский С.Е., Беренов А.Д. Машины непрерывного литья слябовых заготовок. М.,1991 г., 271 стр.
  4. Чумаков С.М., Делекторский Б.А., Сорокин А.Н., Евтеев А.П. Журнал "Сталь". Возможности автоматического предупреждения о прорывах на выходе кристаллизатора.№5, 1998 г., стр. 22-26.
  5. Haers Ir. F., Thornton S.G. The application of mould thermal monitoring in the two-strand slab caster at Sidmar, Belgium// Steelmaking conference proceedings, 1993. p 425-436.

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