In order to improve the speed of power flow calculation and meet the requirement of real-time calculation

the iterative methods for linear equations are applied to the power flow calculation. When the spectral distribution of the coefficient matrix is relatively scattered

however

the speed of iterative method is slow and even not convergent. The coefficient matrix is needed to be pre-treated to solve the problems mentioned above. Firstly

the characteristic of Jacobi matrix in the power flow calculation is analyzed and segmentally processed based on the PV and PQ nodes. The bigger numbers are found and act as preconditioners. Then

the inverse matrix of the preconditioners is multiplied by the coefficient matrix A and the constant item b

and the original linear system is transformed into a new equivalent linear system which can be easily solved. The speed of solving linear equations in power flow calculation is highly improved. The simulation result shows that the algorithm can solve the power flow equations efficiently.