Multi-Terminal Soft Open Point with Anti-Islanding and Over-current Protection Capability

To increase the reliability of distribution networks, back-to-back converters-based soft open points (SOPs) are emerging as supportive devices for flexible power dispatch and fault isolating under abnormal conditions. However, the existing SOP control schemes are characterized by a master-slave configuration, and the malfunction of the master converter will paralyze the whole SOP system. Further, the existing SOPs are controlled at the current feeding mode, which cannot support isolated loads during the islanding fault. In view of these challenges, this paper develops a reliable and unified control scheme for the multiterminal SOP. The proposed solution can regulate the power flow during normal conditions, provide the grid-forming functionality for islanding cases, and limit the current after a short-circuit fault autonomously without detecting faults or switching modes.