Influence of load characteristics on the power/voltage stability of HVDC systems. I. Basic equations and relationships

Recently, the influence of load characteristics on the power stability of a specific HVDC system configuration had been shown. This points to a more fundamental influence of load characteristics on the power/voltage stability of HVDC systems in general. Thus, a fundamental analysis of the influence of load characteristics on the power/voltage stability of three typical HVDC system configurations is carried out in this two-part work. Three aspects are treated; (i) the basic power/voltage stability equations incorporating load characteristics, the effect of load characteristics and system parameters, (ii) the relationships between the maximum power and voltage sensitivity based methods for all the configurations incorporating load characteristics, (iii) the most unfavourable load characteristics with respect to degrading power/voltage stability margins and the sensitivity of these margins to load characteristics. This paper, which constitutes part 1 of the work, presents (i) and (ii) while a companion paper dealt with (iii).