Security and stability study of planning UHVAC/DC hybrid transmission system

This paper presents the security and stability study of planning UHVAC/DC hybrid transmission system using digital and analog hybrid real-time simulation. The building of digital electromagnetic transient and physical simulation models of planning UHVAC/DC power grid was introduced, then detailed simulation of UHV power backbone was presented. The study include as following: Single Fault, Critical failure of ac system, polebipolar emergency outage of dc system. Simulation results show that: Ac power system failure will lead power fluctuation at UHVAC transmission channels, but the system will restore stable operation after ac fault was cleared. When dc system occurs polar emergency outage, planning UHV system was stable, but for bipolar emergency outage, it need trip off generators at sending system to ensure the system stability. 2015 UHV power backbone meet the requirements of Guidelines for Power System Stability, this network structure is feasible.