Reconfigurable Converter-Formed Soft Open Point- Assisted Dynamic Restoration for Distribution Systems with Cold-load Pickup

Improving the power supply resilience under extreme conditions is an important construction goal faced by modern distribution systems (DSs). In this paper, we develop a dynamic restoration framework for renewable DSs with cold-load pickup (CLPU), assisted by the reconfigurable converter-formed multi-terminal soft open point (R-SOP) to minimize the de-energized loads and renewables curtailment under extreme weather events. Traditional SOP often designed as symmetric capacity topology, which may limit the DS restoration quality by the converter capacity of symmetric SOPs. To address this, a dynamic network reconfiguration model of DSs is established that embedded with R-SOP, whose typical feature is the asymmetric converter capacity design while keeping the total port capacity unchanged compared with traditional SOP. On this basis, a multi-period distribution service restoration model is formulated integrating the converter reconfiguration of R-SOP, DS topology changes and coordinated actions of flexible resources to enhance the restoration level and improve the renewable energy utilization. Moreover, restoration strategies that ignore the CLPU phenomenon may face remarkable gap from the realistic system operating conditions. Accordingly, a frequency-constrained dynamic restoration model is proposed in a faster-timescale to respond to the CLPU and restore the DS in a reliable and adaptable manner. Numerical simulations on two modified IEEE test systems and an actual distribution system verify the effectiveness of the developed framework.