Fault Current Correction Strategies for Effective Fault Location in Inverter-Based Systems

The grid of the future will integrate various distributed energy resources (DERs), microgrids, and other new technologies that will revolutionize our energy delivery systems. These technologies, as well as proposed grid-support functions, require inverter-based systems to achieve incorporation into the overall system(s). However, the presence of inverters and other power electronics changes the behavior of the grid and renders many traditional tools and algorithms less effective. An inverter is typically designed to limit its own current output to avoid overloading. This can result in both voltage collapse at the inverter output and limited energy being delivered during a fault so that protective relays cannot respond properly. To avoid sustained faults and unnecessary loss of service, it is proposed that either supercapacitor or flywheel energy storage be utilized to energize faults upon overload of the inverter to achieve fault current correction. This paper will discuss these challenges for inverter-based system fault detection, explore fault current correction strategies, and provide MATLAB/Simulink simulation results comparing the effectiveness of each strategy.