The usage and combination of renewable energy resources (RES) that leads to distributed energy resources (DER) are developing rapidly in power system architecture nowadays. Some of the reasons are insufficiency of fossil fuels in the future, reduce greenhouse gases emission, and enabling consumers to have flexible energy utilization.

Unlike conventional power generation and distribution, generation capacity of DER is low. Thus, there are needs to integrate different types of DERs and load with microgrid. The microgrid enhanced with power electronics can offer better quality of power supply and higher efficiency and dependability of service.

Despite all the benefits, microgrid also has its own challenges, some of it are operation in normal or islanding mode, plug and play operation, protection, power quality, security, voltage and frequency control, system stability and energy management. Maximum value of the fault current during grid-connected mode and islanding mode are significantly different and it will be in two directions depending on the fault location. Thus, the selection of various protection devices (PD) and the protection coordination will be challenging as well. Protection system of the microgrid should be able to identify the fault, disconnect the fault and clearing the fault in minimum time span without disturbing the whole system. It should also be capable of meeting the requirement of both grid-tied mode and islanding mode.

Technical challenges of DC microgrid protection are DC fault current characteristics, grounding effect, fault interruption problem due to the lack of natural zero current, and less system inertia and low stability. Fault detection in DC microgrid is more complex if we compare it to AC microgrid. This is mainly due to the lack of frequency, phasor and sequence components. This PhD research will critically review various existing protection methods and PD to overcome the technical challenges of DC microgrid. In addition, this PhD research will also be using hardware-in-the-loop testbed for confirming the software simulation results.

This PhD research is aiming to investigate the most optimal fault protection strategy to dispatch energy among different parts inside DC microgrid. The research will also consider the economic and reliability aspect of the scheme.