Power communication technology is an important part of the digitalization of power systems in smart grid. Our goal is always to build a digital communication network with high bandwidth, security, and reliability. At present, our power communication technology has experienced power line communication (PLC), Plesiochronous Digital Hierarchy (PDH), Synchronous Digital Hierarchy (SDH) optical fiber communication, optical transport network (OTN), and packet transport network (PTN) technology. Facing the requirements for automatic power control system and digitalization in the future, it is also necessary to introduce the flexible small container optical service unit (OSU) for production services into the existing OTN architecture, so as to efficiently transmit production service signals at a rate of lower than 1 Gbit/s. The generated OTN OSU structure effectively carries existing wavelength division multiplexing (WDM) and multi-service transmission platform (MSTP) optical transmission networks, making it the best choice of the special wide area network (WAN) technology in the future electric power industry, and adapts to the development of highly-reliable automatic control services of automatic power control and digital services of industrial Internet of Things (IoT).