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

Abstract

In this article, a fuzzy logic controller (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.

Improved power quality based PVDG system using different optimised MPPT controllers

“…There are four main stages in FLC which are named as-fuzzification, base rule, inference mechanism, and defuzzification [23].Fuzzy logic is the collection of multi-valued logic in which there are two states either true or false and so the range of logic variables is from 0 to 1 and also there is the involvement of partial-truth region.…”

Optimal control for a photovoltaic integrated grid system using PSO and modified whale optimization to enhance power quality

“…Where t is the current iteration,  A and  C is coefficient vectors. The vectors  A and  C are calculated as follows, shown in equations (13) and (14).…”

“…The technical criteria both for the utility grid side and PV system side must be satisfied to ensure the safety of the PV installation, reliability of utility grid, and effective use of the generated electricity [13,14].…”

A novel control technique for various modes of grid-connected PV system to improve power quality.

“…The PV module will generate maximum output if it is optimally controlled. The number of optimizing techniques such as Hill climbing perturb & observe, fuzzy logic controller (FLC), etc [10,11]. can be applied to track the maximum output from the PV module [3].…”

“…Active wave shaping i.e., pulse width modulation is an effective approach to control the power quality [13][14][15]. Therefore, an effective controller, tuned with the PWM technique is required to maintain all the control parameters in the PV system without using external circuitry for controlling power quality indexes, however, the system could be controlled only with complete information about the system [10,16]. The PV module's manufacturer provides the datasheet with some specifications however, it is not complete data to understand the dynamic behavior of the system [17].…”