A comparative analysis of PI & FLC based grid connected PV system with power backup to improve power quality

Abstract

In this article, a fuzzy logiccontroller (FLC) tuned DC-link controller is presented. This controller is utilized to enhance the power quality characteristic of grid-integrated PV systems with power backup in comparison to the PI controller, without any filter at PCC (point of common coupling). The primary purpose of these controllers is to maintain power to the DC/AC sides by maintaining the DC-link voltage under transient conditions. The proposed system is tested with a non-linear load; hence, the proposed system requires power quality enhancements on PCC. By using both controller power flow control, reactive power compensation and harmonic mitigation is done on PCC, after that grid current becomes sinusoidal. For the power quality improvement, no filter/shunt active power filter (SAPF) is connected to PCC, only proposed inverter current controller improves the power quality at PCC by using these controllers. Using the MPPT (maximum power point tracking) Controller, the maximum power extraction feature is also included in this paper to extract maximum power from the PV module under varying atmospheric circumstances. The power backup unit is also connected with this system, power backup unit includes a battery controller which works as a boost and buck converter according to system requirements, along with a battery. On the MATLAB/Simulink platform, the control scheme and functioning of both controllers are tested, and the results are validated as satisfactory. According to IEEE 519, the grid current THD is below 5% when the suggested control system is implemented.