oa An Improved Photovoltaic Power Generation System with Quasi-Z-Source Inverter and Battery Storage

I. Introduction

Photovoltaic (PV) energy generation has been one of the most active research areas in the past decades, because it is essentially inexhaustible and environmental friendly with respect to the conventional energy sources.

However, nowadays the higher initial installation cost, lower efficiency and reliability of the PV system still block its widespread application. To overcome these problems, our project focuses on a novel PV system, including the novel PV interface inverter by combination of the battery into the quasi-Z-source inverter (qZSI). All of these aim at controlling output power of the PV system to the grid flexibly, thus, to extremely improve the scientific and economic developments of Qatar.

II. Methods And Results

This paper proposes the charging and discharging control of qZSI with battery for PV power generation system.

1) To monitor the battery state of charge (SOC), the output power-based SOC control is designed.

2) The closed-loop control of shoot-through duty ratio and direct power control of space-vector modulation are separately designed to acquire the stability of DC and AC voltages.

3) Related simulations and experiments are performed.

4) A 3 KW hardware experimental platform is being set up based on the TMS320F28335 32-bit floating-point DSP controller and PM100CLA120 Intelligent Power Module (IPM) for main power switching devices. We have done optimization design on the hardware circuits. Up to now, the hardware prototype has been partly set up.

III. Conclusions And Future Work

The acquired results indicate that the proposed control algorithm could stabilize the DC bus voltage and realize the battery charging and discharging without extra circuits, providing a significant method to enhance the performances of PV power generation systems.

Next step is to go on building the setup and perform related experiments, and then apply the designed control methods on the multilevel PV system, which is in accordance with our project timeline.