交直流混合输电系统交互作用量化指标研究

Interaction Index Parameters of AC-DC Hybrid Transmission Systems

中国直流多落点系统的电网格局在南方电网、华东电网和四川电网中形成。现有的多馈入交互作用因子和多馈入短路比没有考虑交直流并联多落点系统送、受端换流站间的相互影响,没有计及换流站的无功损耗。统筹考虑所有换流站的相互作用,采用复功率形式计入换流站无功损耗,将现有交互作用因子和多馈入短路比扩展到交直流并联多落点系统中,提出复功率短路比,证明系统强度不仅与电网结构参数和直流功率的变化有关,还受换流母线电压的影响。通过算例仿真说明复功率短路比对换流母线抗电压跌落能力有一定表征作用,更加适用实际研究的需要;弥补了现有短路比定义未考虑无功影响而导致评价过于乐观的不足,有助于指导实际交直流互联电网的安全稳定分析及其规划设计。

The HVDC muhi-feed systems have been formed in South China Power Grid, East China power grid and Siehuan power grid. The existing multi-infeed interaction factor （MIIF） and multi-infeed short circuit ratio （MSCR）, however, do not consider the interactions of converter stations in the AC -DC hybrid transmission system and the reactive losses of converter stations. With consideration of the interactions of all converter stations and their reactive loss in fonu of complex power, the complex power muhi-feed short circuit ratio （CMSCR） is pruposed in this paper through extending the existing MIIF and MSCR to the AC/DC parallel multi-feed systems. It is proved that the strength of grid system is not only related to the power grid＇ s structural parameters and DC power variations, but also affected by the bus voltage of the converters. Simulation ease study indicates that the CMSCR can characterize, to some extent, the auti-voltage drop eapability of the converter buses and is more suitable for praetieal studies. Moreover, it can offset the deficiency of existing short eireuit ratio （SCR） for not considering the reactive influences whieb often lead to over optimistic evaluation results, and is helpful for AC-DC interconneeted power grid stability analysis and planning.