Dynamic performance of static and synchronous compensators at an HVDC inverter bus in a very weak AC system

This paper discusses the performance of dynamic voltage control devices at the inverters of very weak AC power systems. The types of compensation considered are: (a) static VAr compensators (SVC); (b) synchronous compensators (SC); (c) a mix of the two; and (d) fixed capacitors. Although the primary purpose of these compensators is to control voltage at the AC bus, their dynamic performance during system disturbances is a very important factor. The investigation includes the behavior of the various voltage control options under AC and DC disturbances. The paper shows that the SVC has the fastest response for load rejection type of overvoltages, but can cause serious problems with recovery during undervoltages caused by single phase faults. The CIGRE benchmark model for HVDC control studies has been modified and used in this study. In particular the effect of local load has been included