<p>Peer-to-peer controlled microgrids are typically powered by multiple grid-connected inverter-interfaced distributed generators (IIDGs) and offer the merits of adaptive load sharing, voltage support, and plug-and-play functionality. However, dedicated protection relays for microgrid faults have not yet been fully developed, limiting the development of microgrids. To address this problem, this paper proposes a fault detection scheme based on positive-sequence fault components for peer-to-peer controlled microgrids. The fault component characteristics of the microgrid system containing multiple grid-forming (GFM) IIDGs are analyzed in detail by modeling the faults of the system first. It is found that the phase difference between the fault component node voltage and fault component current phasors can discriminate forward faults from reverse ones in various scenarios. Then, a fault detection criterion with low requirements for communication or data synchronization and resilience to the structure and operation modes of microgrids is proposed. The scheme is accompanied by a hybrid fault starting criterion that can adapt to the vast differences in fault response between the grid-connected and islanded modes, and a complementary discussion of frequent non-fault events is presented. The experimental results from hardware emulation and software simulation prove that the proposed scheme is highly effective and resistant to varying fault types and impedance.</p>