A New Shared Module Soft Open Point for Power Distribution Network

Abstract

The soft open point (SOP), as a sort of promising flexible power electronic device in place of the normal open point, can improve the operating flexibility of a distribution network. However, the traditional cascaded-H-bridge (CHB)-based SOP requires a large number of H-bridge modules and high-frequency transformers, which are costly and bulky. In this article, a shared module SOP (SMSOP) topology is proposed based on CHB. The modules of the SMSOP topology are divided into shared modules and nonshared modules. Both the input and output stages of the nonshared modules are connected in series with the terminals of the shared modules to connect two ac grids. Compared with the traditional CHB-based SOP, this topology can reduce the number of H-bridge modules and high-frequency transformers. Mathematical models are derived, and control strategies as well as feasible areas are discussed. A design method is proposed to minimize the number of modules. Finally, the correctness and validity of the proposed SMSOP are verified by simulation and experimental results.