Experimental Research On Smart Microgrid System

With the continuous progress and development of society,the microgrid system has become an important part of the power industry.It can efficiently use various distributed power generation systems,has a high penetration rate of renewable energy,and The shortcomings of large grid power supply are too concentrated to make up,so it is very important for the research of microgrid.In this paper,based on the wind and solar storage complementary smart microgrid experimental system as a platform,the 10 k V overhead line subsystem and the photovoltaic grid-connected subsystem are analyzed experimentally.The main research contents are as follows:First,it describes the background and significance of the research on the smart microgrid experimental system platform,and introduces the current research progress on microgrid technology at home and abroad.Afterwards,the experiment platform based on the wind-solar hybrid smart micro-grid is introduced.The platform includes photovoltaic,wind,energy storage,energy management,and simulation of 10 k V overhead lines and other systems.With real-time monitoring function of various system parameters,it can realize single operation such as island / grid connection /production / experiment and free combination of various operation modes,and can complete seamless and fast cut between microgrid and distribution network within 10 ms,overhead The line can simulate many types of line short-circuit faults.Next,the simulation of the 10 k V overhead line constructed in the microgrid experimental platform is analyzed.The results show that the three-phase imbalance in the line is mainly caused by the imbalance between the three relative ground capacitances in the line,and Installing capacitors in the circuit can effectively improve the three-phase unbalance phenomenon.The harmonics appearing in the line are caused by the excessively high 5th and7 th harmonic content caused by the operation of the booster transformer core in saturation.In addition,the photovoltaic grid-connected subsystem in the platform is analyzed,and it can be concluded that the lower the inverter power of the grid-connected inverter,the higher the harmonic content generated.In addition,when a single-phase photovoltaic system is incorporated into different types of large power grids,it will cause unbalance of the three-phase voltage at the grid connection point,and when incorporated into the low-voltage distribution network,the harmonics at the grid connection point are mainly It is the 3rd harmonic.When it is incorporated into a 10 k V overhead line,the harmonics at the grid connection point are mainly the 5th harmonic.Finally,according to the microgrid experiment platform,the experimental analysis of theinfluence of the short circuit fault of the distribution network on the photovoltaic grid-connected system is carried out.It can be drawn from the results that the difference in short-circuit fault distance of the distribution network does not have a great impact on the photovoltaic grid connection,which is mainly caused by different types of faults in the distribution network,and three relative ground faults are more important The influence of the net is greater.