Simple Tuning Rules for Feedforward Compensators Applied to Greenhouse Daytime Temperature Control Using Natural Ventilation

In this work, simple tuning rules for feedforward compensators were applied to design a control strategy to regulate the inside air temperature of a greenhouse during daytime by means of a natural ventilation system. The developed control strategy is based on a PI (Proportional-Integral) controller...

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Bibliographic Details
Published inAgronomy (Basel) Vol. 10; no. 9; p. 1327
Main Authors Montoya-Ríos, Ana Paola, García-Mañas, Francisco, Guzmán, José Luis, Rodríguez, Francisco
Format Journal Article
LanguageEnglish
Published Basel MDPI AG 01.09.2020
Subjects
Air temperature
ARX model
Compensators
Computer simulation
Controllers
Daytime
disturbance rejection
Feedforward control
Greenhouses
Identification
Mathematical models
Monitoring systems
Performance enhancement
PID control
Polynomials
Proportional integral
Solar radiation
Strategy
System identification
Temperature control
Transfer functions
Tuning
Variables
Ventilation
Weather
Wind speed
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Summary:In this work, simple tuning rules for feedforward compensators were applied to design a control strategy to regulate the inside air temperature of a greenhouse during daytime by means of a natural ventilation system. The developed control strategy is based on a PI (Proportional-Integral) controller combined with feedforward compensators to improve the performance against measurable external disturbances such as outside air temperature, solar radiation, and wind velocity. Since the greenhouse process dynamics is very complex and physical non-linear models are mathematically complicated, a system identification methodology was proposed to obtain simpler models (high-order polynomial and low-order transfer functions). Thus, an easier procedure was completed to tune the PI controller parameters and to obtain the feedforward compensators expressions by following a series of modern and simple tuning rules. Simulations with real data were executed to compare the control performance of a PI controller with or without the addition of feedforward compensators. Moreover, real tests for the developed control strategy were carried out in an experimental greenhouse. Results demonstrate an enhanced control performance with the presence of the feedforward compensators under different weather conditions.
ISSN:2073-4395
2073-4395
DOI:10.3390/agronomy10091327