Analysis and assessment standards of power stability of multi-send HVDC systems

The asynchronously interconnected Yunnan Power Grid is a typical multi-send HVDC system. So far, research on systems with multiple high voltage direct current (HVDC) links is mainly focused on multi-infeed HVDC systems, and the assessment standards for power stability of multi-send HVDC systems have not been discussed yet. In this study, firstly the quasi-steady-state model of a two-send HVDC system is built and an analysis of power stability based on the maximum power curve is given. Secondly, the relationships between power stability and two indices (Multi-infeed Effective Short-circuit Ratio and the Multi-infeed Interaction Factor) are discussed. Lastly, the assessment standards for power stability of multi-send HVDC systems are proposed and a case study of Yunnan Power Grid is presented, which may provide useful instructions for the planning process of multi-send HVDC systems