A novel strategy for frequency control of islanded greenhouse with cooperative usage of BESS and LED lighting loads

Abstract

In microgrid perspective, a greenhouse (GH) can exchange power with the utility grid in the grid-connected mode or operate autonomously in the islanded mode. In this paper, a two-stage control strategy for the frequency control of the islanded greenhouse is proposed. The first stage is primary frequency control (PFC) that battery energy storage system (BESS) and LED lighting loads (LEDLLs) intercept the frequency deviation in a coordinated manner. BESS can inject or absorb power and LEDLLs also can decrease or increase their power consumption, respectively, for shortage or surplus power situations. One of the novelties of this paper is to use this capability of LEDLLs for participation in PFC, which is very suitable and useful since they are the major load in the GH. Also, the dimmable capability of LEDLLs is used for changing their power consumption to avoid unwanted and extreme frequency deviations in the islanded mode. The second stage is the secondary frequency control (SFC) that the slow responding diesel generators (DEGs) gradually change their output power to reestablish load-generation balance and consequently, restore frequency to its nominal value. Also, a novel strategy for emergency frequency restoration with the cooperation of the BESS and the LEDLLs is proposed for situations that DEGs alongside other DGs in the greenhouse cannot provide the power of total GH loads. Several case studies are performed on a GH under study by simulation in MATLAB/Simulink software that the results show the effectiveness of proposed control strategy.