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The grid connected inverter is the core component of the photovoltaic grid connected power generation system, which mainly converts the direct current of the photovoltaic matrix into alternating current that meets the grid connected requirements, playing a key role in the efficient and stable operation of the photovoltaic grid connected power generation system.This paper uses fuzzy PI control model which to improve the performance of intelligent photovoltaic grid-connected inverter to simulate the intelligent photovoltaic inverter system, using mathematical analysis and reasoning methods for model analysis,adopts two-stage three-phase LCL grid-connected inverter, establishes mathematical models in two-phase synchronous rotating and two-phase static coordinate systems, and adopts an active damping strategy based on grid-connected current. Based on existing research and empirical analysis,aiming at the disadvantage of poor dynamic response of repetitive control, an improved repetitive control strategy is adopted, and the controller is analyzed from two aspects of stability and dynamic performance, and the simulation model of photovoltaic grid-connected power generation system is built. Use experimental analysis method to verify the effectiveness of the model in this article,The experimental results show that the simulation system of intelligent photovoltaic grid-connected inverter considering fuzzy PI control proposed in this paper has certain effects. [ABSTRACT FROM AUTHOR]

This paper presents a low voltage ride through (LVRT) control strategy using an active power oscillations based reference current generation approach for grid tied solar photo voltaic (SPV) system under line-to-ground (LG) and double line-to-ground (LLG) faults. Proposed control strategy minimizes the harmonics injected into the grid, as well as oscillations in injected reactive power and DC-link voltage. Further this control strategy provides a dynamic control of active and reactive powers, the flow of sinusoidal currents into the grid, and avoids the disconnection between the utility grid and SPV system during faults. A proportional resonant (PR) current controller is developed in a stationary reference frame to achieve the power quality by fulfilling the grid codes. Simulation and experimental results are presented to highlight the merits of the proposed control scheme. [ABSTRACT FROM AUTHOR]

In this paper, the hybrid synchronization based grid forming (HS-GFM) control and coordination strategy are proposed for the inverter and boost converter to provide frequency support. As the main contribution, the inertia power and damping power are designed with HS-GFM based coordination strategy between inverter and boost converter. The inertia power can be obtained from DC capacitor and photovoltaic system in deloading mode independently. Besides, the damping power can be realized from the PV inverter in deloading mode. After that, the small signal models of inverter and boost converter considering grid frequency coupling are constructed with simplified single input single output (SISO) model to guide the parameter selection. Further, the grid synchronization stability, synchronization bandwidth and grid strength influence on the frequency response of the PV inverter can be analyzed with SISO model. Compared with conventional DC voltage based GFM, HS-GFM can improve stability especially in strong grid with slight reduction of synchronization bandwidth while it has the risk of instability in weak grid if parameters are not proper. Compared with phase locked loop (PLL) based control, the proposed HS-GFM control achieves a fast response under frequency excursion with better stability in weak grid. Finally, realtime and offline simulations are carried out to verify the proposed strategy and analysis. • Inertia and damping power are designed with hybrid synchronization based GFM control. • The DC side thevenin equivalence of boost converter is obtained for SISO analysis. • SISO model of PV inverter is built for stability analysis and parameter selection. • Comparisons with conventional GFM and phase locked loop based control are presented. [ABSTRACT FROM AUTHOR]

• Study of PV power plant with quasi-Z-source cascaded H-bridge multilevel inverter under failure. • Control system to provide a suitable DC voltage at the input of the VSI and ensure the grid power delivery. • Control tested from simulation results under different operating conditions and HIL experimental results. • Correct response of the developed control strategy with failure in qZSI module. At the present time, quasi-Z-source cascaded H-bridge multilevel inverters (qZS-CHBMLI) have gained attention in photovoltaic (PV) applications, due to their advantages over traditional multilevel inverters. They allow single-stage power conversion of a PV power plant by independently adjusting the DC voltage in each module; thus, each PV array operates at the maximum power. This advantage permits dispensing with a DC/DC boost converter and reduces the number of modules required. This paper develops a novel control strategy for a qZS-CHBMLI connected to a single-phase system that guarantees proper operation when a fault occurs in a quasi-impedance source inverter (qZSI). The control strategy is employed in a grid-connected qZS-CHBMLI with three modules, each one with a quasi-impedance network, a 4.8 kW PV array and a voltage source inverter (VSI), with H-bridge topology. The purpose of the control system is to deliver a suitable DC voltage at the input of the VSI and ensure the grid power requirements after a fault in a module. The proposed control system is evaluated through a 40 s simulation in MATLAB/Simulink® in two cases: A) analysis of the system behaviour when there is a variation in the operation limit equation; and B) evaluation of the control strategy under dissimilar operating conditions. In addition, an experimental setup based on an OPAL RT-4510 unit and a dSPACE MicroLabBox prototyping unit is employed to validate the results. The results confirmed the correct response of the applied strategy with the failure of a single module. [ABSTRACT FROM AUTHOR]

• A power-decoupled current source inverter (PD-CSI) is proposed for the operation in an unbalanced grid to reduce the current rating of the DC-link inductor. • A model predictive control is proposed for the PD-CSI. It achieves high performance in both stability and rapidity. • A space vector pulse width modulation is proposed for the PD-CSI. It helps to reduce the voltage rating of the ripple storage capacitor. The current source inverter (CSI) is a promising interface between the Photovoltaic (PV) panel and the three-phase AC grid. It boosts the PV panel voltage by a DC-link inductor and converts the maximum available PV power. In an unbalanced grid, double-line-frequency pulsating powers will be generated in the CSI, increasing the rating of the DC-link inductor and impeding the maximum power point tracking (MPPT) operation. To address this issue, a power decoupling (PD) circuit for a three-phase CSI is proposed in this paper. By using the DC-link inductor and active switches multiplex, the proposed PD circuit can reduce the current rating of the DC-link inductor with fewer active switches, and no detrimental power components are introduced to the utility grid. Moreover, to concurrently control multiple objectives without multiple loops, a model predictive control (MPC) method is further proposed for the PD-CSI, achieving a rapid response of PD-CSI. Besides, a space vector pulse width modulation (SVPWM) method is proposed for the PD-CSI to enhance the utilization of DC voltage, helping to reduce the voltage stress of the ripple storage capacitor. The priorities of the proposed topology and the corresponding control and modulation methods are finally verified by comparative experimental results. [ABSTRACT FROM AUTHOR]