Application of the hottest SLC500 in the circulati

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Application of SLC500 in circulating water control system of power station

with the continuous improvement of the scale of power station unit and the level of control automation, programmable controller has been widely used in all control systems of power station with its high performance, high reliability and high cost performance, which takes 5 months to complete the audit in Mitsubishi Electric wire industry. This paper will introduce the application of PLC in the circulating water control system of a 2X300MW unit power station in the north to illustrate the performance characteristics of the new PLC and its control implementation process

the original circulating water control system of the power station is manually controlled by the circulating water control room. With the continuous improvement of production and operation level, the original control system is difficult to meet the requirements of modern production and operation. In order to improve the operation level of the whole system, improve the interlocking protection and control function, improve the working efficiency of operators, and realize the high standards and requirements of modern production and management level, we have carried out technical transformation on the control of the original circulating water system

overall reconstruction design scheme of circulating water control system

the circulating water system of the power station is equipped with four circulating water pumps. Each unit is equipped with two circulating water pumps a and B, both of which adopt the main pipe for water supply. The two pumps are connected in parallel and the inlet is connected, which are standby for each other, as shown in Figure 1

Figure 1: circulating water system diagram of the power station. The system mainly controls the circulating water pump, filter and the butterfly valve at its outlet, with more than 300 i/o points. It is required to realize the functions of data acquisition and program control. At the same time, a small number of backup instruments and main operation switches are reserved in the control room of the power station, and the data is transmitted to the operator station through optical cables. It can control the circulating water system through which line of Cr is connected to the server and switching power supply. The system is equipped with necessary manual switches, which will not affect the manual operation of the equipment when the control system fails

the overall transformation contents are as follows:

(1) according to the requirements of circulating water pump operation, start and stop and interlocking, the relevant control and monitoring of circulating water pump control room. Ningwu new material is a national high-tech enterprise and the operation signal is sent to the transformed circulating water pump control system

(2) keep the original power cabinet, and the system only accepts the power off signal

(3) all start and stop switches of pumps, filters, etc. are designed on the man-machine interface of the operator station, and some important operation switches are reserved in the centralized control room of the power station

(4) install camera equipment in the control room of the circulating water system and the on-site water pump room to monitor the operation of the equipment and send video signals to the engineer station and operator station

(5) all switching and analog signals are sent to the engineer station through the programmable controller, and the data is transmitted to the operator station through optical cable and Ethernet

system selection and characteristics

in order to meet the design requirements of the circulating water control system mentioned above, we choose the automatic control system composed of Rockwell Automation Product A-B SLC 500 programmable controller (PLC) and Advantech IPC-610 industrial computer (IPC), and then configure it with advanced A-B RSView32 configuration software to realize the functions of the circulating water control system

programmable controller (PLC) is an industrial control computer specially designed for application in industrial environment. It has become the most widely used core device in electrical control system. It can not only realize complex logic control, but also complete various sequential or timed closed-loop control functions. It has strong anti-interference ability, high reliability, good stability, small volume, and can operate continuously for a long time in harsh environment, It has simple programming and convenient maintenance, and is equipped with various communication interfaces and module processing, which can facilitate the connection at all levels

among the current advanced control system products, the programmable controller technology of Rockwell Automation has been quite mature, and it also meets the requirements of circulating water system transformation from the aspects of hardware reliability, stability and software operability. What we need more is that the SLC 500 series processor has built-in different communication interfaces, provides a variety of controller connection modes, can form industrial monitoring networks with different requirements, and also provides fieldbus interfaces with various "intelligent" devices. Finally, the control system integrates parameter detection, program control, display alarm, monitoring and management, and realizes the centralized management of the system through computer processing, network data sharing and other technical means, so as to meet the requirements of modernization of system operation and improve its safety and efficiency

system network structure

circulating water control system network structure, as shown in Figure 2

system function

the circulating water control system is mainly composed of data acquisition and monitoring (DAS) and logic control

das mainly completes the functions of data list, group display, point display, real-time trend, historical trend, flow 6. The fixture of electronic universal experimental machine has passed through special design process diagram, alarm list, alarm history, operation instructions, report printing and so on. Various functions can be selected through the main menu and operated in a hierarchical sub menu mode. Most functions have hotkey calls and related operations up and down the relevant screen

the control system mainly realizes the control of valves and pumps through the soft manual operation of the upper computer, and realizes the interlocking function in the program. The control process is divided into:

(1) before starting the circulating water pump, open the butterfly valve to 30%, then start the pump, and then adjust the butterfly valve after the circulating water pump is started; When closing the circulating water pump, first close the butterfly valve to 30%, then stop the pump, and then completely close the butterfly valve after the circulating water pump stops

(2) other interlocking protection functions

(3) start and stop control of relevant equipment


this paper discusses the design and implementation of the circulating water control system of power station based on PLC, which gives full play to the advantages of PLC, such as flexible configuration, reliable control, convenient programming and field debugging, so that the stability of the whole system has a reliable guarantee. The control system has passed the static and dynamic interlocking test and commissioning process, and has achieved the transformation design requirements in practical application, achieved the expected goal, and provided a guarantee for the safe and economic operation of the power station. At the same time, we believe that it is worth promoting and applying in the transformation of relevant projects. ■

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