Abstract: In general, only such system factors as different system operation conditions, different fault types and fault time are considered when over-voltage protection parameters for series compensation (SC) devices are designed, while the influence of SC device fault is seldom considered. But in fact, the cases of SC device faults exist in practical operation, which directly influence the SC device parameters. In this paper, by using the current data of China Southern Grid and parameters of three sets of series compensation (SC) devices in Baise substation and their protection configurations, the models of overhaul of SC and false action of over-voltage protection are established. The interaction influence between parameters of SC devices in the same substation are studied in such operation conditions as false trigger and refusing trigger of GAP, and SC device out of service. Study results show that it is reasonable to consider the effect of a set of SC faults on parameters of other SC over-voltage protection devices when carrying out SC basic design.