过程控制毕业设计双容液位控制系统设计.pdf

双容液位控制系统设计 摘 要 本设计完成对双容液位控制系统的设计。该系统的简要工作流程为：水泵将储水 箱中的水往上压，流经调节阀继续往上注入上水箱。上水箱的水再注入下水箱，下水 箱再回流至储水箱。PLC 通过设在下水箱底部的压力/液位变送器读取下水箱的当前 液位值，经 PID 指令运算来控制调节阀的开启程度。采用 PLC 作为主控制器，由 CPU226 模块和 EM235 模块组成。选择 PID 控制作为主控制策略，通过 PLC 中的PID 指令运算实现对调节阀的 PID 单回路控制。通过控制回路实现本地与远程的选择，通 过组态软件实现手动与自动的切换。电路中设有断路器和热继电器，能实现对电路的 保护和报警。通过运用 A3000 过程控制实验平台来检验本设计的可行性和合理性。 关键词：CPU226 ；EM235 ；PID ；A3000 ；自动化；过程控制；双容液位；PLC ；单 回路；双容液位控制系统设计 兰州理工大学 双容液位控制系统设计 Abstract The design is completed on the two-tank liquid level control system. Brief workflow of the system are: water pump to the water tank up in pressure, flows through the control valve to continue up into the tank. On the water tank under the tank and then into the next tank and then back to the tank. PLC through a water tank at the bottom of the next level transducer to read the current level value under the tank, to control by the PID instruction operation control valve opening degree. By PLC as the main controller, the CPU226 module and EM235 module. Select PID control as the main control strategy, through the PLC PID instruction in the operation of the control valve to achieve single-loop PID control. Through the control loop to achieve local and remote option, through configuration software manual and automatic switching. Circuit with circuit breakers and thermal relays, to achieve the protection and alarm circuit. A3000 process control through the use of experimental platform to test the feasibility and rationality of the design. Key words: CPU226 ；EM235 ；PID ；A3000 兰州理工大学 双容液位控制系统设计