A Novel Approach for Resilient Protection of AC Microgrid Based on Differential Phase Angle of Superimposed Complex Power

In the last decades, the penetration rates of microgrids (MG) and distributed generations (DGs) are exponentially soared. Despite the fact that MGs can improve the reliability and resilience of distribution networks, designing a reliable protection scheme for alternating current microgrids (AC-MGs) is still a challenging task. The existence of various types of DGs and frequent changes in MGs’ operational modes, islanding, sudden increment in the value of loads, and penetration rate variation of DGs are some of the main issues which should be considered to design a reliable and resilient protection scheme for MG. In this paper, a novel adaptive resilient protection scheme employing synchronous current and voltage obtained from micro phasor measurement units (μPMU) located at both ends of the protected line, is presented. A new index is also devised to detect all types of internal and external faults based on differential phase angle of superimposed complex power (DPASCP). The threshold value of the proposed index is adaptively updated according to variations created in the network. This scheme can detect various types of faults in different locations fast and accurately in both grid connected and islanded mode of operation. The performance of the proposed protection scheme is also evaluated on IEEE 33-bus and 15-bus test networks in non-fault critical conditions such as grid-islanding switching, connection and disconnection of different DGs with changing in penetration rates of them, and load encroachment. The results demonstrate the capability and superiority of the suggested protection scheme.