Two-stage Photovoltaic Grid-connected Inverter Research Articles

A Novel Two-Stage Photovoltaic Grid-Connected Inverter Voltage-Type Control Method with Failure Zone Characteristics

This paper investigates how to develop a two-stage voltage-type grid-connected control method for renewable energy inverters that can make them simulate the characteristics of a synchronous generator governor. Firstly, the causes and necessities of the failure zone are analyzed, and thus the traditional static frequency characteristics are corrected. Then, a novel inverter control scheme with the governor’s failure zone characteristics is proposed. An enabling link and a power loop are designed for the inverter to compensate fluctuations and regulate frequency automatically. Outside the failure zone, the inverter participates in the primary frequency regulation by disabling the power loop. In the failure zone, the droop curve is dynamically moved to track the corrected static frequency characteristic by enabling the power loop, resisting the fluctuation of grid frequency. The direct current (DC) bus voltage loop is introduced into the droop control to stabilize the DC bus voltage. Moreover, the designed dispatch instruction interface ensures the schedulability of the renewable energy inverter. Finally, the feasibility and effectiveness of the proposed control method are verified by simulation results from MATLAB (R2016a).

Applying Kalman filter on sensor noise cancelation in grid – connected inverter

This paper presents the control model of three phase grid- connected photovoltaic inverter based on the analysis of operating principle of two-stage conventional gridconnected inverter. The mathematical model of inverter under dq frame is set up and the overall control strategy of two-stage photovoltaic grid-connected inverter is proposed in this paper. To overcome the distortion general caused by switching effect on sensors, a Kalman filter is introduced. The control strategy was simulated on Matlab – Simulink to verify the steady and dynamic of model, improving the quality of electrical power to consumers.

Numerical modeling and research on nonlinear dynamic behaviors of two-stage photovoltaic grid-connected inverter

In this paper, the piecewise smooth state equation of a two-stage photovoltaic grid-connected (TPG) inverter is established and studied; based on the solution to the piecewise smooth state equation of the TPG inverter, effects of the photovoltaic array voltage on nonlinear dynamical behaviors of the TPG inverter are analyzed by using bifurcation diagram, folded diagram, 3D phase diagram, and Poincaré section. Then the nonlinear dynamical behaviors of TPG inverter are compared with the conventional one. And a strategy of expanding the input voltage range for the TPG inverter is explored. Finally, the nonlinear dynamical behaviors in it caused by the variation of main circuit parameters: such as the output inductance and capacitance of the front-stage, as well as those of the second-stage, are discussed through slow-scale bifurcation diagrams. Studies have found that it is effective to expand the input voltage range of the TPG inverter by segment control of the photovoltaic array voltage, and the chaotic phenomena in the TPG inverter can be avoided by increasing the parameter values of inertial devices such as output inductance and capacitance in the front-stage appropriately, but the values of output inductance and capacitance in the second-stage should be away from the multiple noncontiguous region, since it can cause chaotic behavior. The above work may have important guiding significance and application for improving the stability and efficiency of two-stage photovoltaic grid-connected inverter based photovoltaic power generation system.

Analysis of the Deadbeat Control Algorithm for Photovoltaic Grid Connected Inverter Output Current

Photovoltaic grid connected inverter is the core interface device in the photovoltaic power generation system to grid. The power quality of photovoltaic power generation system is affect by the waveform of output sinusoidal AC current directly. In this paper, current deadbeat control algorithm and a two-stage photovoltaic grid-connected inverter control strategy are proposed by analyzing the derivation of a photovoltaic grid-connected inverter. According to the grid connected Photovoltaic system features, a set of three-phase Photovoltaic grid connected inverter is designed, which rated power is 15 kW. The deadbeat control algorithm is introduced, based on the analysis of photovoltaic grid connected inverter topology, grid connected voltage, current, power, and the current waveform distortion rate. The deadbeat control algorithm is effective to control the three phase inverter output current through the system simulation and analysis.

Research of Single-Phase Two-Stage Photovoltaic Grid-Connected Inverter

In order to meet the needs of different occasions for the low power photovoltaic grid-connected inverter, designed a single phase 3KW two stage photovoltaic grid-connected inverter. DC - DC link used an improved ZVT- Boost circuit to achieve maximum power point tracking (MPPT) control of the panels, DC-AC link used frequency doubling unipolar SPWM control to ensure the full-bridge inverter circuit output current waveform distortion rate minimum, at the same time to achieve the highest efficiency.