Abstract:
In regions with high electricity demands, the AC power grid is densely populated, leading to difficulties in controlling power flow and issues with excessive short-circuit currents. The scale effect of AC power grids trends to saturation, necessitating the development of new hybrid AC/DC grid structures. To improve the controllability, safety, and stability of AC/DC hybrid power systems, three typical AC/DC transmission methods are first analyzed in terms of their technical characteristics: full DC asynchronous interconnection, full AC synchronous interconnection, and conventional AC/DC hybrid interconnection. Next, in accordance with the unique transmission configuration of single-AC multiple-DC transmission sections, the operational characteristics of this configuration are analyzed in terms of its ability to control power flow,
N−1 overload, short-circuit currents, frequency stability, voltage stability and synchronous stability. Principles for constructing the single-AC multiple-DC transmission section are also provided. Finally, case studies are conducted in a modified IEEE 11-bus system. The results demonstrate that the single-AC multiple-DC transmission configuration can simultaneously compromise the controllability, safety, and stability requirements of hybrid AC/DC power systems, making it a highly promising grid structure with practical applications.