Operation analysis of modified Sen transformer for flexible distribution interconnection

Flexible distribution network is an effective solution to improve the operation performance of distribution system, and soft open point (SOP) is regarded as the key equipment of flexible distribution network. However, the installation and operation cost of SOP based on fully controlled power electronic devices are relatively high, which limits the practical application of SOP in distribution networks. To solve this problem, a novel flexible interconnection device based on modified Sen transformer (MST) is considered. The power control mechanism of MST is illustrated, and the node voltage conditions that limit MST access are derived. Then, the node power regulation capability of MST is described in detail, and the impact of system operating states on the operational boundary of MST is analysed. A 10.5kV distribution network in Tianjin is used to verify the regulation perfor- mance of MST. Results indicate that MST can independently regulate the active and reactive power of the controlled bus to the desired level.