  Contingency analysis (CA) plays a critical role to guarantee operation
security in the modern power systems. With the high penetration of renewable
energy, a real-time and comprehensive N-1 CA is needed as a power system
analysis tool to ensure system security. In this paper, a graph-based
preconditioning conjugate gradient (GPCG) approach is proposed for the nodal
parallel computing in N-1 CA. To pursue a higher performance in the practical
application, the coefficient matrix of the base case is used as the incomplete
LU (ILU) preconditioner for each N-1 scenario. Additionally, the re-dispatch
strategy is employed to handle the islanding issues in CA. Finally, computation
performance of the proposed GPCG approach is tested on a real provincial system
in China.
