Research On Islanding Detection Of The Single-Phase Miniature Photovoltaic(PV) Grid

Since the21st century human society has was in the ecological environment seriously polluted and the shortage of fossil energy state. Solar energy is an inexhaustible and unlimited clean energy. At present, the solar power is mainly divided into the solar-thermal power generation and photovoltaic power generation. It has been more and more attention in application and popularization by people that has advantages of no pollution, safe and reliable. And then, the islanding will frequently occur in the process of photovoltaic (PV) grid power generation. Also the harm of islanding effection is more and more serious so that solving the problem of islanding is imminent. It is practical and significance problem to seek quickly and efficiently islanding detection method. The purpose of this paper is to study the islanding issues of the single-phase photovoltaic (PV) grid.In the first place, this paper studies what produce theory and harm in islanding, research status in domestic and overseas and testing standards. Secondly, This article adopted the active frequency island method, positive feedback active frequency shift method and active current disturbance method to detect islanding based on comparison and analysis to the islanding effection of the principle of active, passive and other detection methods and the advantages and disadvantages. Last but not least, these three methods are discussed in detail the working principle, advantages, disadvantages and blind detection range. Through MATLAB simulation study shows that using active electric current perturbation method in grid inverter can quickly detect the island state, stop inverter operation, and does not exist detection blind area when inverter single run in state of output power greater, equal to and less than the consumption of load power.The islanding protection circuit takes STC12C5A162S chip as the control core which is composed of voltage and current detection circuit, IGBT the control core which is composed of voltage and current detection circuit, IGBT driver circuit, LC filter circuit, fault protection circuit and display control circuit, etc. Also writing the procedures and designing the related control flowing chart of islanding detection algorithm. Combined with the design of hardware and software, we set up1000W/220V single-phase photovoltaic (PV) grid power generation system. And then it completed the single-phase grid experiment test and adopt active current perturbation method to detect islanding in this system. At last, it summarizes to this study and makes further prospect for future research.