Dynamic State Estimation based protection of microgrid circuits

Microgrid protection presents challenges because of the presence of inverter interfaced resources which results in insufficient separation between fault and load currents. This paper uses the Dynamic State Estimation (DSE) based protection (EBP) method for the protection of microgrid components. The paper demonstrates that this method provides a reliable protection system as opposed to traditional methods. Specifically, we verify that traditional protection functions such as overcurrent, distance etc. fail to provide selectivity in protection of microgrids. The EBP method can be viewed as an evolution of current differential protection and requires GPS synchronization if measurements come from different metering devices. The method mainly determines whether the measurements are consistent with the model of the protection zone by use of the chi-square test. Numerical simulations prove that the method can correctly respond to different fault types and locations. The method works equally well for three-phase balanced or unbalanced systems, two-phase or single-phase systems, and radial or networked microGrids.