Synchronous condensers causing transient instability in a highly stressed grid

Inhalt:
This paper is focusing on the comparison of the two main technologies for delivering dynamic reactive power compen-sation, namely STATCOMs and rotating synchronous condensers, in terms of the capability to support the grid voltage subsequent to 3-phase faults. Within that scope, dynamic RMS simulations on a highly stressed system, representing the planned German transmission system of the year 2035, have been performed. It turned out that, for achieving a stable voltage recovery after the fault, significantly less dynamic reactive power compensation devices are needed if solely STATCOMs are used, compared to the case if only synchronous condensers are utilized. This difference is due to the different physics of the two devices, which is further explained in this contribution.