Transient overvoltages on an HVDC bipolar line during monopolar line faults

A series of monopolar line-to-ground faults were performed on a bipolar HVDC transmission system and the induced transient voltage on the sound pole recorded and compared with various system modelling techniques. Longitudinal overvoltage profiles are developed and selected parameters varied in an investigation of factors influencing overvoltage magnitude and wave shape. Selected examples of field data are included to support the conclusions concerning fault location, distortion, line termination and prefault voltage.