The increasing penetration of distributed generation in low-voltage microgrids introduces significant challenges for power sharing and voltage regulation, particularly in four-wire systems subject to unbalanced loads and neutral currents. This paper proposes a coordinated control framework for four-leg grid-forming voltage source converters aimed at improving power sharing, stability, and neutral current management in islanded microgrids. The proposed approach combines three complementary mechanisms: (i) passivity-based output impedance shaping in the \(\alpha \) \(\beta \) axes to ensure robust interconnection stability, (ii) a physics-based enhancement loop derived from the \(\Delta \) E/R relation of resistive feeders to improve active power sharing without increasing droop gains, and (iii) a rating-scaled zero-sequence impedance synthesis that enables decentralized neutral current sharing proportional to converter capacity. The control strategy is evaluated through analytical modeling, small-signal reasoning, and extensive statistical assessment using a Monte Carlo framework that captures load imbalance uncertainty. Detailed electromagnetic transient simulations performed in PSCAD/EMTDC further validate the proposed methodology. The results demonstrate that the proposed framework improves active power sharing accuracy to below 2% error while maintaining bounded voltage deviations and enabling proportional neutral current distribution among converters. In addition, voltage unbalance levels remain controlled under load uncertainty, confirming the effectiveness of the proposed control architecture for reliable operation of low-voltage four-wire microgrids.
