随着人们生活水平的提高和可持续发展战略的需要，污水处理越来越受到社会的重视。污水是破坏环境的一个重要原因，当前中国污水处理自控系统相对落后，污水处理成本非常高，污水厂排放的污水水质不稳定。对污水进行净化处理既能够起到环境保护的作用，又可以进行处理水的回收与利用，从而节约水资源。为了提高污水处理的质量和效率，同时能节省大量的人力物力资源，建立一套先进实用有效的污水处理过程的自控系统，使得运行效果得到优化提升，减少运行费用，具有重要意义。 本文针对安庆污水处理厂的二期改造工程，进行了大型污水处理厂的电气控制系统的设计和实施。项目运用了PLC控制、现场总线、监控系统、传感器及化工仪器仪表在线检测等技术，选用了德国西门子公司的编程软件和组态软件，以及各类仪表设备，构建了大型污水处理厂的电气控制系统。 论文主要从三个方面展开工作：一是确定总体的自动控制系统设计方案，并对配电系统进行设计；二是根据污水处理工艺选择合适的设备，包括PLC选型、现场检测仪表选型以及工艺设备选型等；三是进行PLC控制系统软件设计和监控系统设计。本项目电气控制系统设计完成后，经过近半年的安装调试，系统运行稳定，各项参数指标均达到设计的要求，工程现已成功验收，取得了显著的经济效益和社会效益。

With the improvement of people's living standard and the strategy of sustainable development, wastewater treatment has aroused much attention of the society. Wastewater is one of the major factors that pollute the environment. The automatic controlling system of wastewater treatment in China isn’t very advanced. The cost of wastewater treatment process is high. The water qualities of the treated wastewater are unstable. The water purification treatment can not only play the role in the environmental protection,but also recycle water and utilization, so as to save water resources. In order to improve the quality and efficiency of wastewater treatment, and save a lot of manpower and material resources, it is necessary to establish a set of advanced and practical and effective wastewater treatment process of the automatic control system. It can optimize and upgrade the effect of operation,and reduce operating costs. According to the Anqing wastewater treatment plant two phase of the renovation project, the design and implementation of large-scale wastewater treatment plant electrical control system. The project used PLC, Field bus, monitoring system, sensing element and testing devices for instruments and apparatuses, and so on. We selected PLC and WinCC of Siemens Ltd. Of Germany. With many kinds of instrumentation, we designed a construction of a large-scale wastewater treatment plant electrical control system. The thesis main work includes three aspects：No.1 is to determine the overall design scheme of automatic control system and power distribution system. No.2 is to select the suitable equipment according to the wastewater treatment process, including the model of PLC, testing instrument and the process equipment etc. No.3 is to design software system and monitoring and control system. After the completion of the project design of electrical control system, and nearly six months of installation and debugging, the System is running stable. And the parameters have reached the design requirements. The project has been successful acceptance. It gained remarkable economic benefits and social benefits.