Power Flow Coupling Characteristics Analysis and Coordinated Optimization Strategy for AC/DC Hybrid Transmission Sections

At present, the continuous growth of renewable energy integration and power grid load demand has placed higher requirements on the transmission capacity and power flow control capability of power systems. Owing to its flexible and controllable power flow characteristics, DC transmission technology has been introduced into AC grid structures, making AC/DC hybrid power grids an important development trend. However, the increasingly prominent power flow security issues caused by the complex coupling characteristics between AC and DC systems pose new challenges. First, this paper conducts an in-depth analysis of the operating mechanisms and power flow coupling characteristics of AC/DC hybrid transmission sections under various operating conditions. To address the dual challenges of insufficient utilization of transmission capacity and power flow security, a novel AC-like AC/DC power flow coordinated optimization strategy is proposed. Based on phase angle coordinated control, the autonomous response capability of the DC system is leveraged to perform real-time control and optimization of transmission power on lines, maximizing the capacity utilization of AC/DC hybrid transmission section while satisfying security and stability requirements. Finally, simulation studies based on a transmission network containing two four-machine AC systems verify that the proposed strategy fully meets the security and stability requirements of AC/DC hybrid power grids, providing reliable technical support for the coordinated development of future AC/DC grids.