The Optimization of Action Sequence of Security and Stability Control System in HVDC Near-Area

With the increase of high voltage direct current(HVDC) transmission capacity, the consequences of HVDC faults on the AC receiving end power grid is becoming increasingly severe, so the security and stability control systems (SSC) with complex functions and strategies are required. But the functions of the AC and HVDC control systems in the near zone power grid are coupled with each other. The incorrect information identification collected by the SSC and the incorrect coordination of multiple action timing may cause incorrect operation of the SSC, which may lead to serious problems such as HVDC blocking or AC system instability. This paper focuses on typical cases of incorrect operation of the SSC in multiple HVDC near zone power grids, analyzes the root causes of the unexpected actions, proposes targeted optimization and improvement measures, and conducts simulation verification based on RTDS. Based on the research of the above typical cases, the general principles for designing a HVDC near zone SSC strategy are proposed, which effectively improves the reliability of the SSC and ensures the safe operation of the high voltage AC/DC hybrid power grid.