A Novel Methodology for Optimal Allocation and Sizing of Soft Open Points in Distribution Networks

Abstract

The Soft Open Point (SOP) is an emerging power electronics device that can be implemented in distribution networks to realize active power flow control, reactive power compensation and voltage regulation, and post-faults service restoration. This paper presents a novel methodology for the optimal allocation and sizing of SOPs in active distribution networks. The objective of the proposed method is to minimize the total active power loss in distribution systems. A two-stage optimization framework is developed. In Stage 1, the loss sensitivity index (LSI) and voltage deviation index (VDI) are used to identify candidate locations of SOPs. A new approach to derive LSI is proposed in this paper, where LSI is used to find initial candidate nodes. The candidate nodes are then grouped lateral-wise and used to form the candidate pair of nodes for SOP placement between laterals. In Stage 2, a mathematical optimization model is developed using AC power flow for optimal sizing of SOPs. The capacity of each voltage source converter (VSC) of the SOP is individually optimized to obtain the optimal capacity. Finally, case studies using a modified IEEE 33-node test system are carried out to verify the effectiveness of the proposed method. The proposed method shows better performance than an existing method in reducing active power loss, improving voltage profile and implementing smaller capacity of SOPs in distribution networks.