Application Of Improved Resistance-typed High Temperature Superconducting Fault Current Limiter In Photovoltaic Power System

With the increasing demand for energy and the depletion of fossil energy,the problem of environmental pollution caused by fossil energy is becoming more and more serious.Solar energy is a clean and pollution-free new energy source with large reserves and wide distribution,as one of the most ideal energy sources for environmental protection,solar energy has been widely used by human beings.With the increasing capacity of photovoltaic power grid,short circuit current in power system is increasing,which poses great threat to power equipment and even threatens personal safety.In order to limit the short circuit current value to the rated range of the switch equipment,there are many electric equipment that limit the fault current.The electric network containing the photovoltaic power generation system is ideal for the resistance type superconducting fault current limiter.The resistance type SCFCL is simple,the response speed is fast,and the resistance type SCFCL of the system has no effect on it,if the system is running normally.When short circuit fault occurs,the resistance of resistance type SCFCL increases rapidly to limit short circuit current and short circuit capacity.Resistive SCFCL integrates detection,triggering and limiting flow,and has self recovery function.Resistive SCFCL can effectively limit short circuit current and improve power supply quality.The basic principle of photovoltaic power generation system and the characteristics of the main system components was first introduced in thispaper,introduces the basic working principle of the solar cell,expounds various MPPT algorithms,analyzes the structure and working principle of the inverter,and then summarizes the basic and electrical mechanism of the superconductor,and analyzes the structure of the SCFCL by analyzing the different machine structures.Understand their respective characteristics and working principles.Based on the requirements of power grid to SCFCL,the last part of the paper focuses on improving the basic principle and current limiting characteristics of resistive SCFCL.In this paper,a three level inverter grid connected PV system with limited current by using resistive SCFCL is simulated by Matlab/Simulink.When various short circuit faults occur at the load end,the current limiter is placed at the B1 of the photovoltaic terminal,the load end B2 and the B3 end of the grid end respectively.The voltage and current value of the photovoltaic end B1,the load B2 and the grid end B3 arerespectively obtained.When the current limiter is placed at the B1 of the PV terminal,there is no current limiting phenomenon,which is due to the photovoltaic(PV).The system is equivalent to a current source.The current size depends on the intensity of the light,which is not related to the short circuit of the power system.Therefore,the current is almost invariable,so the current limiter is placed at the end of the light and the current is not limited.The current limiter at the load side has the best current limiting effect because the closer the fault current is,the better the current limiting effect is.When the current limiter is placed at the end of the grid,the finite flow effect is achieved,but no load side is obvious because the current limiter is far away from the fault point,so the current limiting effect is poor.The simulation results show that the resistance type fault current limiter installed at the appropriate location can effectively limit the short-circuit fault current and has good current limiting effect.Improve the stability of photovoltaic power system and improve the power quality of power grid.