Impedance-based stability analysis of multiple STATCOMs in proximity

With the advanced technology of power electronics and the increasing load demand in modern power systems, it is possibly necessary to have multiple STATCOM (static compensator) units in physical proximity to share the work burden and to tackle emergencies too. Then there is a possibility that these STATCOMs may interact in an undesired way, which could drive the system into unwanted oscillations and potentially into instability, due to dynamic phenomena generated and dependent on the respective controllers of these converters as well as on the system impedance in their operating region. On the contrary, a system with a single STATCOM would not be subject to these specific occurrences. To investigate this problem, this paper extends the impedance-based stability analysis in order to explains the dynamics behind. A sample transmission system and its corresponding simulation model are used as test bed to conduct the study.