| Abstract |
This paper presents a study of overvoltages generated on a HVDC poles resulting from converter-blocking with misfiring of by-pass valve; which injects an AC voltage component into the DC line. The magnitude of this component depends on the nature of fault, DC line impedance characteriestic, DC smoothing reactor, AC network short circuit power and the converter control system parameters. The influence of these parameters on this abnormal overvoltage is discussed. This phenomena is studied using a HVDC simulator for a point to point DC link and for a multiterminal transmission link having three terminal converter stations. The summary of the obtained results shown in this paper, indicates that the abnormal overvoltages may be suppressed by the selection of appropriate DC system parameters, by installation of auxillary reverse-bias diode or by installation of a damping circuit tor the DC lines. Also the proper and optimum design of the central loop parameters gives an important damping effect on these overvoltages. |
