Analysis of overvoltage levels in the rigid bipolar MMC-HVDC configuration

Bipolar high voltage direct current (HVDC) transmission systems based on modular multilevel converters (MMC) are intended to be used in several upcoming projects. This contribution performs a profound analysis of occurring overvoltages in a single point grounded rigid bipolar transmission scheme, where the MMC topology equipped with half-bridge (HB) submodules is utilized. In order to derive voltage stresses affecting the dc cable system, a detailed parametric study is performed by means of time­domain simulations. Obtained results are discussed with regard to different station grounding configurations.