Implementação de uma malha de controle para um sistema de bombeamento: um estudo de caso para a modulação de vazão em uma planta piloto

Abstract

This work describes the connection of instrumentation and the control of a pilot plant located in the Laboratory of Hydraulics at UFMG. This pilot plant consists basically of a water tank which receives water from a pump driven by an induction motor connected to a frequency converter. Originally, the pilot plant operated in open-loop and consequently itwas not possible to generate prespecified water flow profiles required to test reduced models of hydraulic structures. The purpose of this work was to implement a closed-loop control system in order to enable the pilot plant to produce the aforementioned water flow profiles. The implemented closed-loop consists basically of a differential pressure sensor and transmitter, a PID controller connected to the frequency converter and a PC computer. These devices were connected to the pilot plant and tuned in order to achieve the goal of water flow control.Besides connecting the equipment, a mathematical model based on first principles was derived for the pilot plant. Such a model was coded in MATLAB programming language and can be used to simulate the pilot plant operating both in open and closed-loop. Some PID tuning methods were implemented in order to tune the controller. After this was done, it was possible to successfully produce standard water flow profiles using the pilot plant. Some of such results are presented and discussed in this work.