Optimal Operation of Greenhouses in Microgrids Perspective

An optimal energy management strategy for greenhouses is proposed in this paper for both grid-connected and islanded modes, i.e., microgrids perspective. Especially, the islanded mode is focused due to the scarcity of resources and inability to suffice all loads during the entire islanded period. In normal mode, the greenhouse can trade power with the utility grid to minimize its operation cost. In islanded mode, only local resources can be used, and thus precedence of different control parameters is defined to optimize the growth of plants. In addition, an algorithm is developed to avoid the acceptable range violation of the same parameter in consecutive intervals. The four major control parameters considered in this paper are indoor temperature, relative humidity, CO₂ concentration, and indoor lighting. In order to enhance the sustainability of the greenhouse, renewable sources, energy storage systems, and combined heat and power units are incorporated into the model. The uncertainties associated with renewable generations and loads (electric, heat, and cooling) are realized via robust optimization method. The effect of uncertainties on operation cost and power trading with the utility grid in grid-connected mode along with operation cost and control parameters' violation intervals in islanded mode are analyzed. Finally, the effect of event occurrence time on the violation intervals of the control parameters is analyzed. Numerical simulations have proved the effectiveness of the proposed method.