A Study Of The Line Protection Scheme Of The DC Microgrid

With the development of power electronics technology,microgrid technology has become the trend of distributed power system in the future.The DC microgrid has great advantages in coordinating and organizing the distributed power sources,thus bringing new vitality to the traditional power grid.At present,domestic and international research on technologies such as DC microgrid topology,key equipment,operation control,etc.has made some significant success.However,the research and application of DC microgrid protection technology still faces challenges.This paper takes the DC microgrid line protection scheme as the research goal,and the main outcomes are:(1)Analyze the DC microgrid in depth,and establish a typical ring low-voltage DC microgrid simulation model with PSCAD/EMTDC.Based on this system model,characteristics of line fault are studied.The research result provides theoretical support for proposing the protection scheme;(2)Analyze the current characteristic after DC microgrid line fault,and propose the direction pilot protection scheme based on the direction of the current fault component.The protection scheme has clear selectivity,simple setting rule,and can quickly isolate faults.The effectiveness of the scheme is verified by simulation results;(3)Cable line is mostly adopted for power supply in current DC microgrid.It is necessary to add a special fault locating device.Under this condition,this paper proposes a dual-terminal distance protection scheme,which utilizes the electrical quantity information after fault occurrence.This protection scheme can isolate fault quickly and realize accurate fault location;At the end of the paper,the research results above are summarized and the further research directions are given.