摘要:本设计研究的是PLC在太阳能集中供热水控制系统中的应用,该系统可以实现大楼太阳能自动化供热水。PLC为该系统的总控单元。指出了系统硬件的构成和系统软件过程的设计。

　　　本系统由水位控制系统，水温控制系统，压力控制系统，防冻控制系统组成。其中压力控制系统是基于变频器的供水系统，采用变频调速的方式，自动调节水泵电机的转速，保持供水稳定，在用水低谷时通过变频器降低频率，降低能耗。在用水高峰时通过变频器增大频率或者增加给水泵，变频频率根据生活用水时间及其他一些影响因素对主控PLC提供信息，对变频器进行调节，使水压恒定于一定的范围从而保证水的不间断供给。课题利用西门子公司s7-200的PLC控制器，实现对系统各部分的自动控制。在已有的太阳能热水器技术的基础上，采用PLC控制系统，实现热水器内水位水温的控制与加热，改善热水器的实际使用功能，从而使太阳能热水器水位水温控制达到更为理想的效果，更能满足居民楼内用户的实际需要。

关键词： PLC；太阳能；变频器；供热水系统；自动控制系统

Abstract:This design is the study of the solar water heating PLC Control System.The system can automation of building solar water heating.System for total control unit of using PLC.And introduces the working principle of solar energy water heater, process and system requirements, focus on the system hardware structure and software design of the system process

　　　The system consists of water level control system, temperature control system, pressure control system, frost control system.Pressure control system is based on a frequency converter to the water supply system, the variable frequency speed way, to automatically adjust the water pump motor speed, and keep the water supply stable in bottom water by the lower frequency, reduce the energy consumption. In the water peak by the increasing frequency or increased water pump, frequency conversion frequency according to life water time and other influencing factors on master PLC to provide information on the adjustment of frequency converter, make constant water pressure in a certain range to ensure uninterrupted supply of water.Subject adopts Siemens s7-200 PLC controller,parts of the system to achieve automatic control.On the basis of the existing solar water heater technology, using PLC control system, the water level in the water heater temperature control and heating, improve the function of water heater of actual use, so that the solar energy water heater water temperature control to achieve more ideal effect, more can meet the residential building within the user's actual needs.

Keywords: PLC; Solar; Inverter; Water heater; automatic control system