Optimal power rescheduling in interconnected AC/DC networks to maintain the voltage stability

Abstract

The main remedial actions to prevent voltage instability problems are load shedding and rescheduling of generating units. In AC/DC networks, the presence of high voltage direct current (HVDC) links equipped with voltage source converter (VSC) provides an efficient active and reactive power support. As the voltage stability is a local phenomenon, the rescheduling of an HVDC link could change the arrangement of critical buses and the stability margin of the entire power system as a remedial action. Considering this problem, a new optimization algorithm is proposed to provide the desired voltage stability margin in interconnected AC/DC networks taking into account the post contingency conditions and minimizing the cost of remedial actions. The regulation of the converter operating point is presented as a novel remedial action. The well-known loading margin (LM) index is used as the voltage stability criterion and different VSC-HVDC structures, i.e. singleinfeed, multi-infeed and multi-terminal HVDC systems are considered. The effectiveness of the proposed algorithm is evaluated using an AC/DC system comprising the IEEE 118bus and New England 39-bus test systems. The results show that the proposed algorithm could provide the desired value of LM with the minimum value of load shedding and the control cost.