基于plc电厂输煤控制系统.doc

摘 要 输煤系统是电厂的重要组成部分，电厂输煤系统运作的性能关系到电厂生产效率以及工人的身体健康。由于早期的输煤系统的自动化水平不高，人工作业量大，维护困难等缺点，与现代化工业需求不相适应，因此提高输煤系统自动化程度是必然选择。 电厂输煤以往的控制方式落后，本文采用S7-200系列的PLC，以PLC为核心，设计电厂输煤控制系统，实现输煤系统的启停，进煤量的检测与调节，及备用系统自动切换功能。首先从输煤系统工艺流程出发，对控制系统分析，设计合理的方案。其次，在硬件部分中对各设备选型，分析需要控制的量，有称重信号，速度信号，报警信号，各设备启停，进煤量调节。以S7-200 PLC作为主控制器，设计电机和变频器的控制电路，绘制电气控制原理图，通过PLC对变频器的控制达到对皮带机运行速度的控制，从而实现进煤量的调节。最后，在软件部分，设计系统流程图和编写系统的控制程序，以及对组态监控界面的设计实现对系统的监控。 在这输煤系统中，进煤量控制调节由触摸屏监控，不用在工业现场人工操作，减少工作量，提高输煤效率。 关键词：输煤系统；PLC；变频器；监控 Abstract The?coal?handling?system?is?an?important part of power plant, and the operating performance of coal handling system will affect the productivity of a power plant and the health of its workers. Since the early coal handling systems have the defects such as low automation?level,?a?large?amount?of?manual?work?and maintenance difficulties, which are incompatible with the needs of modern industry, increasing the automations level of coal handling system is inevitable. The previous control methods?of?the?coal?handling?system?are backward. This thesis used the S7-200 series of PLC as the core to design the coal handling control system which could realize start and stop of coal handling system, detection and regulation of coal feed and automatic switching of backup system. First, with the technological process of the coal handling system as a starting point, it analyzed the control system and designed a reasonable plan. Second, in the hardware part, it selected various devices and analyzed the amount to be controlled, such as weighing signal, speed?signal,?alarm?signal,?motor?start-stop?as well as coal testing and regulation. With S7-200 PLC as the master controller, it designed the control circuit of motor and transducer, drew the electrical control schematics, and realized control over the belt conveyor speed through control over inverter via PLC, so as to regulate the coal feed. Finally, in the software part, it designed the system flow chart, wrote the system control program, and designed the