Study on fast power flow calculation methods of large-scale power systems

Direct and iterative methods are two common solution methods for linear equations.Three methods for power flow calculation in large-scale power systems are compared,namely multifrontal algorithm(MA),GMRES method and FGMRES method.Numerical simulation tests on seven systems including IEEE 118,300 buses and five Poland test systems indicate that the FGMRES method obviously has fewer inner iterative numbers than the GMRES method with ILU preconditioner,but it takes more computing time on the whole.Overall,MA is the fastest.Based on PQ preconditioning,this paper presents a combined GMRES-MA method.MA is used to solve the assisted preconditioning equations,after the Krylov subspace is generated by the GMRES method for each step in the outer-iterations.The results show that,with the scale expanding,this new method has fewer inner iterative numbers than the GMRES method.Furthermore,compared with both MA and GMRES method,the computing time of the new method is decreased.Therefore,this new method is applicable to the fast power flow calculation in large-scale power systems.