PLC控制电厂输煤系统及变频调速的毕业设计.doc

变频调速输煤系统的节能设计 摘　要 火电厂的输煤系统是火电厂的一个重要组成单元，特点是运行情况恶劣，条件复杂，转动机械多，作业线长，设备分散，尤其对运行人员来讲，现场冗员过多且工作强度大，并且粉尘，噪音等影响运行人眼的身心健康。因此，火电厂输煤程控技术是提高输煤系统自动化程度及可靠性程度的必然选择，也是火电厂提高市场竞争能力的必然要求。 可编程控制器（Programmable Logic Controller简称PLC）是一种专门用于工业生产过程控制的现场设备，在设计上有自己的明显特点：可靠性高，适应性广，具有通信功能，变成方便，结构模块化。在现代集散控制系统中，PLC已经成为一种基本控制单元，在工业控制领域中应用前景极其广泛。 然而为了对输煤量进行精确的控制，系统中同时采用了变频调速。变频调速是交流调速中的发展方向，是现代电力传动技术重要发展的方向。变频器不仅调速平滑，范围大，效率高，启动电流小，运行平稳，而且节能效果明显.使用变频器不仅能达到科学用能、节能降耗的目的，而且能够提高自动化水平，改善工艺。 关键词电厂输煤程控；PLC；变频调速  Abstract Construction of coal-fired power plants conveying system is an important component of the power unit, the characteristic is operating conditions, the condition is complex, rotating machinery, long lines, equipment to disperse, especially the operation team, the work and the dead wood too much intensity, and dust, noise in the physical and mental health of the human eye operation effect. Therefore, coveying coal SPC technology is to improve the conveying system automation degree and the reliability of the inevitable choice, but also improve the power plant is the inevitable requirement of the market competition ability. PLC (Programmable Logic Controller PLC) is a kind of special used in industrial production process control field device, go up in the design has its own obvious features: high reliability, wide adaptability, with communication function, into a convenient, modular structure. In the modern distributed control system, PLC has become a basic control unit, in the field of industrial control application prospect extremely extensive. However in order to lose the quantity of coal accurately control, system and used the frequency control.AC variable speed frequency control is in the direction of development is important to modern electrical drive technology development. Converter is not only a smooth speed, range, high efficiency, starting current, smooth operation, and significant energy savings, use the inverter can be used not only to science, energy saving purposes, but also