On the 20th, the first domestic rotating phase shifting power flow control device developed by State Grid Hebei Electric Power Research Institute was officially put into use in Zhuozhou City, Hebei Province. This device can achieve load balancing and loop switching between power lines with just one click without any customer perception, opening up a new technological path for optimizing and regulating the voltage and flow of the distribution network. As of the end of 2023, the installed capacity of distributed photovoltaics in Hebei South Power Grid has approached 18 million kilowatts. The large-scale integration of new energy into the grid has gradually transformed the distribution network from a traditional unidirectional power flow radiation network to a bidirectional power flow active network. This not only increases the complexity of power grid trends, but also increases the difficulty of line voltage regulation. In addition, the integration of diversified and customized loads such as automotive charging stations and data centers also poses higher requirements for the closed-loop operation and power supply reliability of the distribution network. Therefore, the research team of State Grid Hebei Electric Power Research Institute has innovatively proposed vector control technology based on rotating phase-shifting transformers. Researchers used two rotating phase-shifting transformers to generate voltage phasors with constant amplitude and variable phase angle, and injected adjustable series voltage into the line through vector superposition, thereby achieving decoupling control of grid power, flexible adjustment of long feeder voltage, and uninterrupted closed-loop power supply. Based on this technology, researchers have developed the first domestic 10 kV/1 MVA power flow control device and applied it for the first time at the 35 kV Dongchengfang substation in Zhuozhou City, Hebei Province. Due to differences in the wiring method of the previous voltage level, there is a 30 degree phase angle difference between the 514 and 512 lines at Dongchengfang Station in Zhuozhou. If traditional loop closing operation is used, it will cause significant surge currents. After integrating the power flow control device, Zhuozhou Power Supply Company not only achieved flexible closed-loop power supply without power outage, but also effectively solved problems such as line voltage exceeding limits and load overload through fine control of voltage and power flow, significantly improving the carrying capacity and operational efficiency of the regional power grid. Li Tiecheng, the R&D leader, introduced that in addition to the flexible ring closing function, this device can also effectively address issues such as exceeding the voltage limit at the end of the line and the voltage limit at the beginning of the high penetration cable line caused by the connection of high penetration distributed power sources. It has a wide range of application scenarios. (Lai Xin She)