惯性常数对交直流互联系统强弱的评估

Strength Evaluation by Inertia Constant for AC-DC Interconnected System

传统评估交直流系统强度的方法一般只考虑了短路比,而受端交流系统的强弱还跟系统的转动惯量即惯性常数的大小有关。在pscad/emtdc上建立受端单机和受端多机系统模型,通过电磁暂态仿真,针对受端单机系统,考虑在不同的短路比下维持交直流系统暂态稳定所需要的最小惯性常数,得出惯性常数可以作为衡量交直流互联系统强弱的一个评估指标;针对受端多机系统,通过多机系统动态等值方法,得出受端系统的等效惯性常数,通过仿真实验,验证上述结论的有效性。

The traditional strength evaluation of AC-DC system only takes short circuit ratio into account, but the receiving-end AC system strength is also related with the system rotary inertia, namely, the inertia constant. In pscad/ emtdc the stand-alone and multi-machine system model is set up. Thereby for the receiving-end stand-alone system, the electromagnetic transient is simulated considering the minimum inertia constant required to maintain the AC-DC system transient stability at different circuit ratio, and the inertia constant is obtained as an evaluation indicator of the AC-DC system strength. For the receiving-end multi-machine system,inertia constant is obtained by dynamic equiva- lent method. Simulation results verify the validity of these conclusions.