Study Of Coal Mine Drainage Systems On-line Monitoring Frequency Conversion Control System

With the development of electronic technology, the automation level of coal mine drainage system has been increased, and the running of equipment is more secure, reliable;The efficiency of the drainage system and has been improved to a certain extent. To further enhance the efficiency of the drainage system and achieve energy-saving emission reduction of coal enterprises, this paper puts forward design ideas of coal mine drainage systems on-line monitoring frequency conversion control system based on the Programmable Logic Controller (PLC) and the inverter. In the basis of study of centrifugal pump characteristic, this paper expounds the principle of energy saving with frequency control.As the design of mine drainage system is based on the biggest coal mine displacement of normal production, the equipments of systems selection in general tend to be high drainage capacity; motor and pump have left a larger margin. And also affected by water inflow changes with mined in different periods and seasonal changes, working conditions of drainage systems are often needed to be adjusted. This paper uses method of adjusting the motor speed by inverter to change the pump speed to achieve centrifugal pump characteristics change. This method is different from the past by changing the size of the valve opening to change the resistance of the drainage system. Whether the change of pipe network feature or pump characteristics can regulate the working conditions of drainage system. However, the method of valve regulating increases the drainage resistance, so that made input power do a lot of wasted effort ,its utilization rate of electric energy is higher than the method of pump speed adjustment by inverter. The use of inverter to adjust work conditions of pump offer a new way for the energy- saving operation of the drainage systemIn order to solve the problem of complex environment and changing situation under the coal mine. This design uses PLC to control the inverter in the way of communication. Simply by changing the PLC program can easily adjust the control strategies and operating models of system. Through the application of controllable valves, liquid level sensors, test equipment, and explosion-proof surveillance cameras and other automated equipment, composes of PLC-automatic monitoring system. The system can drain automatically according to the water storage level. In the base of automatic drainage, use the method of pump efficiency testing based on thermodynamic theory, combined with the relevant software on-line monitoring pump efficiency. The test software can map out lift characteristic curve, pipe network characteristic curves, pump efficiency curve, determine the operating point and the corresponding pump efficiency , Tons of water 100 meters electricity consumption and other parameters. Pump performance testing provides an important basis for adjusting pump operating conditions and is a higher level of system monitoring.Through the study of this paper, make the PLC automatic control, thermodynamic theory test pump efficiency and frequency conversion technology applied to pump control and monitoring, it has practical significance to improve the safety and efficiency of coal mine drainage systems.