Study On Photovoltaic Grid-connected Power System

Electricity is the basis of the industry to protect the development of the national economy. Because of the uneven distribution and limitation of resources, the energy supply is not adequate all over the world. This has seriously restricted the development of socio-economic and the improvement of people’s living standards. Now, the whole world is looking for green renewable energy to solve the energy crisis. The state is paying more and more attention to the solar energy which is one of the cleanest and most renewable energy. The state has invested a lot of money in new energy industry and made a major breakthrough in it. The solar power comes true because of the photovoltaic.Firstly, working principle and characteristics of the solar cells are introduced, including the types of solar cells, the working principle of the equivalent circuit, and the I-V output characteristics. The engineering model of Photovoltaic is established to get the characteristic curve of a solar cell.Secondly, Maximum power point tracking algorithm for photovoltaic power generation is given. Perturbation and Observation method (P&O) is used to realize the PV Maximum power point trackingThirdly, the working principle of PQ control is introduced. The PQ control model is established in DQ coordinate system. The results of simulation show that the method has good adaptability according to external environmental changing and good dynamic performance.Finally, several common islanding detection methods are introduced. And a combined islanding detection method is proposed. The results of simulation show that the method can detect the islanding phenomenon rapidly and reliably.