Application of PLC of Hubei Institute of Technology in Automatic Control System of Diesel Generator Sets Zhang Jinwei, Chen Gang (Department of Mechanical Engineering, Hubei University of Technology, Wuhan 430068, China) introduced the main functions of single-machine emergency diesel generator sets and I/O settings in PLC control design The focus is on the design ideas and methods for the unit to prepare for operation, start-up, shutdown, regular self-lubrication and operating procedures.
Programmable controller; diesel generator set; automatic control; programmed diesel generator set as backup power source, widely used in various industries such as defense, industry, agriculture, commerce, etc. This paper is developed by Huaguang Electronics Industry Co., Ltd., suitable for small automatic The SH series PLC of the control system is designed for the automatic control system of the single-machine emergency diesel generator set.
1 diesel generator set automation function can set emergency power supply when the mains power failure.
2PLC control design According to the automation function of diesel generator set configuration, this system selects SH-64R1-C type programmable controller, 17 points input, 24 points output, see configuration.
Water temperature high report è±æ“‚é¼· overspeed alarm standby emergency stop oil pressure interlocking speed increase deceleration start stop magnetizing electromechanical closing heater input pump into the oil pump into the mains power loss under voltage electromechanical pressure over water temperature high oil temperature high oil Depressed generator switch manual start manual trip manual stop self-test operation report test reset Because the unit belongs to single-machine emergency automation unit, according to the provisions of GB/T4712 "Automated diesel generator component level requirements", the unit is equipped with the following automation functions.
Automatically start and load. When the mains stops, the control unit automatically starts, speeds up, and closes to supply power to the load. The process does not exceed 3s. Automatic shutdown. After the mains returns to normal, the delay ls is opened, the mains switch is closed, the automatic switching is completed, and then the unit is automatically shut down after 5 minutes of cooling. If the mains fails again during the cold machine, the unit will automatically switch the load to the load to provide automatic protection. During the operation of the unit, if the water temperature and oil temperature are faulty, the sound and light alarm will be given; if the overspeed or low oil pressure occurs, the sound and light alarm will be issued and the emergency stop; if overload, short circuit and voltage abnormality occur , the sound and light alarm signal is issued and opened.
Pre-supply function. When the unit is in the quasi-starting state, the automatic pre-fueling system is put into work, every 4 s, in preparation for the unit to start at any time.
Test machine function. When the unit is continuously shut down for more than 15d in the automatic state, the unit can start the test machine operation by itself, check whether the automatic control function is normal, and make the friction pairs of the unit fully lubricated, in order to prepare the system I/O configuration according to the external wiring diagram of the PLC. With its control function, the ladder diagram of PLC control can be programmed.
2.2 Program design 2.2.1 Preparation and operation program design To ensure that the unit can start smoothly and carry power within 30s after the power failure, the unit must be Zhang Jinyu (1971), female, Huanggang, Hubei, Hubei Institute of Technology, Master of Engineering, Master of Engineering, Research direction: mechanical design and theory - in preparation for operation. The state includes: 1) the temperature of the diesel engine cooling water and the lubricating oil must be kept within the temperature range of the diesel engine running; 2) the diesel engine is pre-lubricated at regular intervals, so that the oil film exists in all rotating parts of the diesel engine to ensure the unit is in emergency start. And when loading quickly, the diesel engine will not be damaged.
Prepare to run the block diagram as shown.
Prepare the program run box. 2.2 Unit start-up procedure design In the state of maintaining the ready-to-run state, the unit is interrupted from the mains to the start of the unit, and sends a closing signal to the main switch to supply power to the load. The whole process must be completed within 30s. The working process is as follows: When the mains is cut off or the external voltage is too low (the voltage drops by 20%), it is confirmed that the start signal is sent to the diesel engine after 2s, and when the starting speed of the unit rises to 300r/min, the start signal is sent to exit the starter motor. And speed up to the rated speed, at the same time, the unit is magnetized and built. Under the condition that both voltage and speed are met, the unit will automatically close the power supply to the load (see).
The operation block diagram of the drying unit start-up program can be started 3 times in succession if the start-up process is unsuccessful. When the start-up, the electromagnet is energized for 6s. When the start-up is unsuccessful, the electromagnet is powered off for 4s and then restarts. If the 3 starts are unsuccessful and the start delay time expires, the start failure audible and visual alarm signal is issued and the standby is enabled. 2.2.3 Unit shutdown program design When the utility power is restored, there are two automatic shutdown functions to choose from. In the "automatic one" state, after confirming that the utility power is restored for 10s, the unit will automatically open the switch and complete the switching. The power supply will be automatically supplied by the mains. The operator should press the power generation according to the usage of the load. The opening button of the machine will make the load be replaced by the mains supply. The above two working modes are the same except for the switching mode of the mains recovery. The shutdown function after switching is the same, both first down to 600r/min, empty Stop after running 5min cold (see).
I pump reset I unit shutdown program operation block diagram If the mains supply is interrupted during the shutdown process, it will directly return to the startup process.
2.2.4 Unit self-lubrication program design Self-test operation time depends on the situation, generally set to 30min, the unit starts automatically, idle speed operation for 5min, idle speed operation for 20min, and finally idle operation for 5min. If the mains power loss occurs during the self-test operation, the unit automatically exits the self-lubricating state and enters the normal emergency power supply state (see).
I self-lubrication time to 1 I unit three start failure failure report 1 I unit speed operation 20min|down speed fw group idling operation again 5~n I stop-machine I unit regular self-lubrication program running plant. 2.5 Unit operation program design After the automatic unit is successfully loaded and put into normal operation, the cycle detection of electromechanical abnormality and mains recovery is started to maintain the normal operation of the unit. In the operation of the unit, if the oil water temperature is high, the sound and light alarm can be performed; if the oil pressure is low and overspeed, the diesel engine can be controlled to stop urgently and an audible and visual alarm signal is issued; if an overcurrent occurs, the main switch is disconnected, and the sound and light are emitted. Alarm signal opening, stop, sound and light report 分M trip, stop, sound and light alarm 丨M trip, sound and light sound and light alarm 丨 mechanical and electrical opening, mains closing, by the city power supply to the power supply unit operating procedures Block Diagram Conclusion The working environment of diesel generator sets is often harsh. Therefore, PLC can improve the anti-interference ability of its control system. In addition, the ladder diagram is simple, easy to understand and easy to design. However, the automatic control of diesel generator sets is quite complicated, involving various aspects. If the above-mentioned programming methods and ideas (which have been successfully applied in simulation experiments) are adopted, the difficulty can be reduced.
Yang Yaochun. Practical electrical wiring and principles. Beijing: China Radio and Television Publishing House, 1991. Huaguang Electronics Industry Co., Ltd. Programmable Controller SH Series User's Manual (1st Edition). 1997. Wan Taifu, Tang Xianyong. Programmable controllers and their applications. Chongqing: Chongqing University Press, 1994. (Continued from page 28) Zhou Shizhen. Dynamic analysis of the height in the idle corrugating roller mechanism. Bao Zhoushi, Ke Hui. The finite element method for the integration of the crown parameters of the idle speed corrugating roller mechanism. Journal of Hubei Institute of Technology, 1998 (4) Huang Xiaocheng. Kinematics and dynamics of high speed corrugated board forming machines. Wuhan: School of Mechanical Engineering, Huazhong University of Science and Technology, 1997.
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