Research On Photovoltaic And Battery Hybrid Grid-connected And Off-grid System Control

Because of the growing demands of energy and the depletion of traditional fossil energy, the importance and urgency of the development and utilization of new energy has become a broad consensus of the international community. Photovoltaic power generation is a kind of clean energy with numerous advantages, such as:clean, pollution-free, flexible installation, noiseless, inexhaustible and so on. It is really an important part of the new energy development and utilization. However, due to the inherent properties of the solar energy, there are also many disadvantages of photovoltaic power generation, such as:randomness, volatility, etc. the continuity and reliability of energy supply are the main problems to be solved in its development. The thesis mainly focuses on the following aspects:First, the thesis discusses three different output parameters of Maximum Power Tracking Control strategy and its application. In order to provide a sustainable and efficient energy, two different systems are proposed here. The first one is a set of independent power supply system, which contains photovoltaic unit and battery unit. There are two buses of the system, the DC bus and AC bus. The thesis discusses the control strategies of photovoltaic, battery, rectifier, inverter and bus voltage. A hierarchical control strategy is used to stable the DC bus voltage under different energy states. Single-phase phase-locked loop has been improved here. Finally, the system is verified by simulation.The second one is a PV-battery hybrid grid-connected power supply system. In order to improving power quality of the hybrid system, the condition of grid voltage distortion and current distortion is considered here. Harmonic current compensation function is used to improve the power quality of the distribution network. The control strategy of the PV-battery unit, grid-connected inverter is proposed here. Positive sequence fundamental voltage and harmonic current extraction methods are also presented here. The topology of the PV-battery system is improved here, new method of battery charging and discharging is proposed.A DSP-based system hardware system is also built to verify the correctness and practicality of the theoretical analysis. TMS320F28335is used here as master chip. Hardware and software design processes and debugging process are expounded here. The results of the system show that the system has meaningful theoretical meaning and practical value.