Internal oscillations in multibridge h.v. d.c. convertors

Suitable models for the analysis of internal oscillations in multibridge h.v. d.c. convertors are described. These oscillations may be due to blocking and deblocking operations, normal commutations between convertor valves and abnormal commutations resulting from the development of convertor faults. A digital-computer program is developed and used to investigate the most severe voltage and current oscillations expected at the convertor main valves and bypass valves.