Abstract :
The question of possible limits of HVDC power supplied to an a.c. system is discussed on a general basis. This limit will be of interest, if a.c. systems are to be reinforced without increasing their short circuit capacity. The two important aspects, i.e. power frequency and harmonic phenomena are discussed in view of investigations on single HVDC converters published earlier by other authors. The results are extended to multiple infeed. It is shown that in contradiction to the general opinion at present, the short circuit ratio presents no limit to the rating of a single converter station, that for multiple infeed each station can be dealt with separately with regard to its rating and that increasing the number of inverter stations connected to the same system does not increase the danger of harmonic instability.
