Optimal integration of DER and SST in active distribution networks

The power distribution system is evolving towards a smart grid paradigm facilitated by infrastructure improvement, innovative technologies, and electronically-interfaced devices. The solid state transformer (SST) promises to be one of the most significant power electronically-interfaced devices to be integrated in the next generation distribution network due to its extensive energy management capability to handle interconnected AC and DC source(s) and load(s). In this paper, a three-phase unbalanced Optimal Power Flow (OPF) algorithm is extended for integrating distributed energy resources (DER) and SSTs in the future distribution networks. The purpose of the OPF is to optimize the economic operations of DERs in conjunction with the SST to improve system efficiency and voltage profiles, while controlling DER penetration. The topology and functionalities of the SST are introduced and modeled in the OPF algorithm. Comprehensive models of loads, conductors, voltage regulators, transformers, and pricing schemes are considered for accuracy. Based on the theoretical foundations, simulations are conducted on the IEEE 123 bus test system. The entire algorithm is also visualized in a quasi-static time-series (QSTS) manner to capture the variability of the system and response of the SSTs in different control modes. This can be adopted by distribution automation enterprises for active distribution networks.