Implementation of greenhouse climate control simulator based on dynamic model and vapor pressure deficit controller

Abstract

This paper discusses the implementation of greenhouse climate control simulator based upon dynamic model with intuitive user interface that provides various options to simulate greenhouse climate under open and closed loop control conditions. The simplified greenhouse climate model based upon mass and energy balance principle, encapsulates the realistic situations in a greenhouse to simulate and analyze the effect of different control strategies (shading, ventilation, cooling or heating) on inside climate for various greenhouse design configurations and under different weather conditions. The model is integrated with the proposed greenhouse-crop vapor pressure deficit (GH-crop VPD) based multi-input multi-output fuzzy climate controller that operates in feedforward mode and regulates greenhouse climate conducive for healthy plant growth and yield. Under closed loop operation, the controller automatically readjusts the operating status and rate of different climate control equipments (shade screen, roof vents, exhaust fan, cooling system and heating system) and simulates automatic control of GH-crop VPD within set limits irrespective of the variations in outside weather conditions. Designed as an educational tool, the simulator was used under open loop to demonstrate how for a selected greenhouse design and weather conditions, different climate control strategies affect greenhouse climate conditions. Multiple simulations run under different scenarios were simultaneously displayed for comparison study and analysis. Further, the closed loop simulations were performed that indicated high performance of the controller in regulating GH-crop VPD under different hot weather conditions and depicted what systems (rate and operating status of different climate control equipments) would be needed to meet desired conditions.