The reliable extinguishment of a single phase-to-ground arc is the key issue for safe and reliable operation in the distribution network. However, since the existing arc suppression methods are normally affected by the line parameters, the residual current (RC) at the grounding point still exists, then the grounding arc is hard to be extinguished reliably. Thus, an adaptive active voltage-type arc suppression (AAVAS) strategy that can reliably inhibit the RC at the grounding point is proposed in this article. First, the mechanism of the traditional voltage-type arc extinguishing method affected by the line parameters is proved, and the variation rules are given for the RC under different fault distances and grounding resistance. Second, the variation characteristics are analyzed for the faulty line current before and after arc extinguishing. On this basis, it is proposed to add the residual voltage compensation ring to the traditional voltage-type control strategy, which can effectively offset the influence of voltage drop on faulty-phase line impedance. Then, the Bode diagram analysis shows that the presented strategy performs well regardless of ground-fault conditions. Finally, the feasibility and effectiveness of the proposed AAVAS strategy are verified by the simulation and experiment results.

A soft open point (SOP) can improve the flexibility of power control and thus further enhance the reliability and economy of distribution networks. However, existing SOP regulation strategies have mainly focused on feeder imbalance regulation and line loss optimization in medium-voltage distribution networks, and the loss of SOPs and distribution transformers are often ignored, which has poor applicability in low-voltage distribution network (LDN). Therefore, a novel two-layer control strategy is proposed for SOPs working in LDN, which can improve economy and reliability of the system simultaneously. In terms of the system layer, the proposed load regulation strategy considering the economical operation area of the transformers can improve the system economy while realizing load imbalance regulation. In terms of the equipment layer, the proposed peer-to-peer control of each port in the SOP can effectively suppress the voltage fluctuation on the DC side. Thus, the system layer commands can be quickly tracked and well conducted. Finally, the feasibility and effectiveness of the proposed two-layer control strategy are verified by simulation and experimental results.

With the increasing integration of renewable energy sources (RES) and single-phase loads, three-phase imbalance and transformer lightly/heavily loaded operation issues has become more prominent in low-voltage distribution networks (LDN). However, existing research on interconnected systems of LDN (ISLDN) rarely addresses the comprehensive management of both three-phase imbalance and lightly/heavily loaded operation issues. To this end, a comprehensive control strategy for three-phase imbalance and lightly/heavily loaded operation in ISLDN based on a four-leg soft open point (F-SOP) is proposed in this paper. Firstly, the comprehensive loss characteristics model of ISLDN including the F-SOP and the transformer are established, revealing that both imbalance and load rate can affect the equipment efficiency. Secondly, considering the objective of minimizing power loss, an optimization dispatch strategy with constraints of three-phase imbalance and the optimal economic operation area is proposed to obtain the dispatch power commands for the F-SOP. Furthermore, an improved peer-to-peer control for F-SOP is proposed to ensure the conduct of the optimization dispatch strategy and enhance stability performance of system. Finally, the effectiveness and feasibility of the proposed comprehensive control strategy are validated by the simulations and experiments. The results show that comprehensive control of lightly/heavily loaded operation and three-phase imbalance in the ISLDN can significantly reduce daily power loss by 62%, improving system operation reliability and economy.