The organic combination of programmable logic controller (PLC) and human-machine interface can fundamentally reduce the use of control elements and simplify the connection procedure. On this basis, distributed control through fieldbus can save cable consumption, and also reduce the installation workload and crane failure rate.
This article will take the application of PLC programmable controller in the lifting equipment of hydropower station as the breakthrough point, and on this basis, it will be deeply explored. The relevant contents are as follows. The central processing unit of programmable logic controller is the control center of the whole system. The functions attached to the programmable logic controller system program receive and store user programs and data transmitted from the programmer; check the status of power supply, memory, input/output ports and alarm timing devices; and analyze the grammatical problems in user programs.
In the running state of the programmable logic controller, at first, the programmable logic controller receives the status and parameters of the input devices in the field in the form of scanning. On this basis, the programmable logic controller enters the input/output port image area separately, reads the user program from the user program memory, and executes the logic according to the instructions when the command is interpreted. The results of arithmetic operations are compiled and bolted in the image area and data registers of the input/output ports of numeric values. After all the user programs are executed, the output state of the input/output port image area and the parameters in the output register are transmitted to the corresponding output module. As we all know, man-machine interface – programmable logic controller – frequency converter is the basic mode of crane control in hydropower station at present, and programmable logic controller is the main control system, thermostatic element which can meet the needs of monitoring and fault alarm of the whole machine. The combination of programmable logic controller and human-machine interface has fundamentally deepened the control accuracy and automation of cranes, and thus reduced the work intensity of operation and maintenance workers. In recent years, most cranes in hydropower stations choose distributed control. The following diagram shows the network connection of crane programmable logic controller. On the basis of defining the network structure of the programmable logic controller system, the hardware related to the programmable logic controller should be configured. This paper will take SIEMENS AG FWB S7-300 as an example. S7-300 uses PROFIBUD-DP fieldbus, while the main station chooses CPU315-2DP central processing unit with built-in loading memory of 80 kilobytes, which can be extended to 512 kilobytes; RAM 48 kilobytes, the extreme number of digital points is 1024, and the extreme number of analog points is 128, which can reach 512 kilobytes. To general application requirements. In addition to the power supply unit, CPU unit and interface unit, the main station also needs to be equipped with input/output port. CPU315-2DP can expand four basic racks, each rack can install eight signal units.
The IM360/IM361 port unit connects the S7-300 backplane bus in series from one rack to the next. ET200 slave station is installed in the operation platform and car room, which is connected by IM153 communication unit and main station communication. ET200 domain name is set by IM153 dialing unit. PROFI-BUS-DP can also connect sensor devices in series, but if the connected device is not identified by programming software, the GSD file of the device DP is required. When the main hoist of the crane is powered on, the programmable controller will check itself at the first time. If the subordinate device of DP network is not abnormal, the hoist will start to operate. In addition to the motor protection function in the vacuum fluorescent display screen, the motor is also equipped with overheat protection and OPC. The crane is controlled by programmable controller and frequency converter, and the man-machine interface is installed in the driver’s cab to monitor the operation of the whole machine. Workers can effectively grasp the basic state information of the crane, and then lay the foundation for stable operation and fault treatment. The color touch operation panel selected in this study has excellent interactivity and is easy to connect with the programmable controller. Because of the use of touch operation panel, the monitoring and operation of the portal crane is greatly simplified. Operators can detect the basic operation of the portal crane through the screen at the first time. On this basis, depending on the actual situation, the operation parameters can be adjusted synchronously. The screen of touch operation panel is based on Web design. Touch screen design not only needs to set up corresponding control functions, but also needs to have strong convenience. The main hoisting screen is mainly used to monitor the operation status of the hoisting converter and the automatic hook beam, which covers the fault number reminder, reset, hoisting degree and hoisting load of the automatic hook beam. In summary, this paper matches the application practice of a large crane device in a hydropower station, applies programmable controller and frequency converter to crane control, attaches to the special function requirements of the crane in hydropower station, puts forward the basic control concept, and designs it on this basis. The design has been put into the lifting equipment of a hydropower station, and the ideal operation effect has been achieved. Man-machine interface-programmable logic controller-frequency converter is the basic mode of crane control in hydropower station at present, and programmable logic controller is the main control system, which can meet the needs of monitoring and fault alarm of the whole machine.
The combination of programmable logic controller and interface has fundamentally deepened the control accuracy and automation of cranes, and thus reduced the work intensity of operation and maintenance workers. The crane we studied is controlled by programmable controller and frequency converter. The driver’s cab is equipped with man-machine interface to monitor the operation of the whole machine. Workers can effectively grasp the basic state information of the crane, and then lay the foundation for stable operation and fault treatment. The color touch operation panel selected in this study has excellent interactivity and is easy to connect with the programmable controller.