Risk analysis of cascading blackout on generator voltage-class-reduction scheme

This paper mainly proposed a method for setting a suitable generator voltage-class-reduction scheme through analyzing the risk of cascading blackout. With the increasing urban load, power supply is insufficient at the load center area. But it is hard and expensive to build a new substation in the load center area directly. Generator voltage-class-reduction operation is an effective and economical approach to solve this problem. It is to make the generator units at the high-voltage terminal accessing to the low-voltage terminal of transformer branch. But it would change the topology and power flow distributions. Since the cascading failures are the intrinsic drawback of power grids, the imbalance of topology and power flow caused by such voltage-class-reduction scheme may increase the blackout risk. Thus, when making the generator voltage-class-reduction scheme, it is needed to evaluate the blackout risk to make the power system at the high level of robustness to against big blackouts. The IEEE-39 bus system was taken as example, and the simulation results indicated that a proper generator voltage-class-reduction scheme can reduce the blackout risk.