The Single-phase Photovoltaic Grid-connected Inverter Control Technology Research

With the booming development of world economy, world energy has become more intense and environmental pollution has become more serious. This has forced people to find and develop unlimited and clean resources, renewable energy. Traditional energy sources will be replaced. Renewable energy industry has been developed rapidly and of photovoltaic power generation and wind power one are the fastest growing two. The development of photovoltaic industry will have far-reaching significance to global environment and energy.In this paper, we took the single-phase photovoltaic grid-connected inverter as the main object of study, studied and analyzed the single-phase grid-connected photovoltaic power system. The main contents include the main circuit, maximum power point tracking, control and islanding, and we carried out analysis and simulation. The method of MPPT is very important. Here, fuzzy control method is selected, its advantages are simple and easy to control a complex system, only need a certain set of fuzzy rules. Under the fuzzy control, model simulation achieves the maximum power point and track fast, and the battery has reached a very high utilization. In this model of the inverter, the dual control, PID and phase lock-in technique, has achieved the ideal output current, high power factor current and well voltage waveform tracking. The principle of the protection is to detect the differences of the output waveform and the power wave in phase and frequency. In this paper, the frequency change is detected by active frequency detection method. When it is unaffordable for the system, the protection will be start so that the system disconnect with the load. In the simulation model, the grid disconnects the connection with load quickly within a detected period after the island so that to avoid the harm.