Photovoltaic Microgrid Operation Control Based On Underfrequency Load Shedding And Low-power Prototype System’s Design And Implementation

Low-carbon lifestyle and the using of environmental energies have promoted the emergence of micro gird because of the increasingly environmental pollution and the exhausting of traditional energy. The establishment of the microgrid would bring a series of benefits, such as increasing the use ratio of power grid and electric energy, reducing the pollution of environment, enhancing the reliability and safety of power supply and improving the quality of electric energy and so on. Therefore, the development of micro grid is the unstoppable trend and main direction of the smart power grids in the future.This paper is based on the 110kW photovoltaic microgrid project of Anhui Polytechnic University, which to solve the problem of load scaled control in microgrid, to establish the islanded mode of microgrid’s low frequency decrease load strategy through fuzzy controller. Meanwhile, it aims to design a miniwatt microgrid prototype system so that the island could run normally.Firstly, the paper introduces the research background and significance of the microgrid system, the research and application value of nowadays microgrid system and the microgrid’s research status and current situation at home and abroad. Then it would present the microgrid system from three aspects:the definition, structure and characters.Secondly, the paper has a detailed analysis about the mathematical model and operating characteristic of the photovoltaic cell, as well as building a simulation model of it in matlab/simulink. Besides, it analyzes different control strategy in microgrid, and build islanded mode of microgrid’s simulation model in matlab/simulink.What’s more, it has done a research on the low frequency decrease load strategy under the islanded mode of microgrid. Due to the imbalance between distributed generators and loads, the change of system frequency is so large that it does not meet the requirements of power quality when it under islanded mode of microgrid. This paper presents an underfrequency load shedding(UFLS)strategy in islanded mode of microgrid which is based on fuzzy logic controller. The control strategy includes a fuzzy logic controller and a load controller. Adding the low frequency decrease load control model in the islanded mode of microgrid which has been built before, the effectiveness of the low frequency decrease load strategy would be verified via emulation proof. Then, the paper introduces the miniwatt microgrid prototype system and runs the operation and adjustment for the built microgrid’s primary experimental platform. The final experiment result would verify the usability of the designed platform.Finally, I have a summary and expectation for this issue. In the paper, the photovoltaic microgrid model has been built, and put in the low frequency decrease load strategy in order to realize the load scaled control when frequency is in an instability circumstance. In the practical application, the conditions are actually more complicated, so the microgrid system and the low frequency decrease load strategy in the paper are required to further research and implementation. In the flourish of the microgrid science and the unceasing generalization of the smart power grid, the microgrid science would be widely used in electrical power system and microgrid will brings convenience for the customers in the near future.