Direct Power Control for Three-Level Multifunctional Voltage Source Inverter of PV Systems Using a Simplified Super-Twisting Algorithm

Abstract

This study proposes a simplified super-twisting algorithm (SSTA) control strategy for improving the power quality of grid-connected photovoltaic (PV) power systems. Some quality issues are considered in this study including the power factor, reducing the total harmonic distortion (THD) of current, compensating the reactive power, and injecting at the same time the energy supplied by the PV system into the grid considering non-linear load. This improvement is achieved by two topologies; controlling both the boost DC–DC converter and the DC–AC inverter that links the PV system to the grid. The DC–DC converter is controlled using proportional-integral (PI) and SSTA to maximize the power generated from the PV panel regardless of its normal and abnormal conditions, while the DC–AC inverter is employed to direct power control strategy with modified space vector modulation using the phase-locked loop (PLL) technique of a three-level neutral-point-clamped (NPC) inverter based on the proposed strategies (PI and SSTA). In addition, a shunt active power filter (SAPF) is used to connect the PV system to the AC grid and feed a non-linear load. To validate the simulation results presented in this paper using Matlab software, a comparative study between the PI controller and the SSTA is presented. The results show the effectiveness and moderation of the suggested SSTA technique in terms of feasibility, tracking performance, less power ripple, dynamic response, THD value, overshoot, steady-state error, and robustness under varying irradiation, temperature, and non-linear conditions.

Experimental Investigations on Photovoltaic Interface Neutral Point Clamped Multilevel Inverter-Based Shunt Active Power Filter to Enhance Grid Power Quality

“…The differential equations below can be used to explain the interaction, with SAPF being regarded as the source of current from the PCC. [11], [27]. The source current in the PCC point is composed of two components, filter currents (IF) and load currents (IL), according to Kirchhoff's current law, which can be expressed as IS = IF + IL.…”

“…An essential challenge in integrating photovoltaic systems with the electrical network is the issue of power quality, resulting from the increasing presence of non-linear loads linked with the electrical network. These loads are contributing to several issues, such as current harmonics, voltage harmonics, power factor, reactive power, and a growing need for active power [9]- [11]. In order to address these problems, grid-connected PV systems use components such as a PV panel, power converter (DC-DC), DC-link energy storage, a three-level SAPF, a grid-connected filter, and the controller circuit.…”

Transient Synchronous Stability Analysis of Grid-Forming Photovoltaic Grid-Connected Inverters during Asymmetrical Grid Faults

“…at 1.5 s. P + reff is set to 0.5 p.u., and D + is set to 25. The reactive power reference (Q + ref ) is set to 0.27 p.u., according to Equation (9). On the basis of Equation ( 12), S + acc = 0.235.…”

“…The traditional GFL-PGC is externally regarded as a controlled current source with high parallel impedance, and GFL-PGCs sample the voltage of the point of common coupling (PCC) during normal operations. The synchronization between GFL-PGCs and the power grid is realized through a phase-locked loop (PLL) [9,10]. However, it is difficult to effectively support the power grid using the control method based on GFL during grid frequency and voltage change [11].…”

Design and Analysis of a Hybrid Stand-Alone Microgrid

“…[23] presents the modeling and simulation of a 1 MW PV plant in the north of Morocco, employing PVsyst software. SAM software can be used for performance analysis of hybrid microgrids by monitoring and analyzing the software components that contribute to the overall performance of the system [24][25][26][27][28][29][30].…”