An assessment of the proportional-integral control tuning rules applied to Photovoltaic Irrigation Systems based on Standard Frequency Converters

In this work, a systematic study of different tuning rules of proportional-integral (PI) control parameters applied to Photovoltaic Irrigation Systems (PVIS) based on Standard Frequency Converters (SFCs) has been carried out. A laboratory system has been implemented to obtain the PI control parameters by means of the most widely accepted tuning rules in control systems. Based on the step-input response modeling, we have been applied the tuning rules of Ziegler-Nichols (ZNs), Chien-Hrones-Reswick (CHR), Cohen-Coon (C-C), Lambda and AMIGOs. Based on frequency response modeling we have been applied the tuning rules of Ziegler-Nichols (ZNf) and AMIGOf. The PI controller parameters obtained from these tuning rules have been evaluated by performing two types of tests: start-up and sudden drop of the available PV power. The experimental results show that the parameter sets obtained by the ZNs, CHR and AMIGOf rules are the only ones that pass all the start-up tests and that the tests of sudden drop of the available PV power are only passed by the configuration obtained by the AMIGOf rules. Therefore, it has experimentally verified that the AMIGO tuning rules based on the frequency response modeling are the only ones that provide adequate values for the PI control parameters for PV irrigation systems.