A Robust Performance Analysis of a Solar PV-battery based Islanded Microgrid Inverter output Voltage Control using Dual-loop PID Controller

This paper proposes a performance indices-based voltage control of an isolated microgrid (MG) system. For this purpose, the system performance parameters such as integral absolute error (IAE), integral square error (ISE), integral time absolute error (ITAE), and integral time square error (ITSE) are obtained. The output voltage of a voltage source inverter (VSI) connected to a solar photo-voltaic (SPV) and battery energy storage system (BESS) based isolated MG is controlled using a dual-loop strategy, and the error profiles are observed. The control signals are generated through the pulse width modulation (PWM) technique. The SPV unit extracts maximum power infeed by using the maximum power point tracking (MPPT) algorithm. The BESS is also provided with PID based charge controller. The uncertainties in the solar irradiance pattern are considered by using a series of random variations at various time instants in the solar insolation data. The overall inverter output voltage control is done using a dual-loop PID-based controller. For this purpose, a closed-loop 'dq' controller is realized by taking the reference signal from the peak value of the 3- phase AC output voltage of the inverter. Various above mentioned performance indices are obtained for the different test cases, and a comparison between the proposed scheme and the model reference adaptive control (MRAC) based scheme is made. Results show the performance of a dual-loop PID controller is more promising as compared to the model reference-based approach.