Compensation method fast decomposition method power flow calculation method for branch network with small impedance

The invention discloses a power flow calculation method for a small impedance branch-containing power network employing a compensation method and a fast decomposition method. Before power flow calculation, a small impedance branch is firstly processed and the small impedance branch is changed into a form of series connection of two branches, wherein the impedance of one branch is z1=r+j(x+xc), the impedance of the other branch is z2=-jxc, and xc is a mean value of reactance absolute values of the branches of which the reactance absolute values are smaller than a reactance threshold in a power system, and is called a normal reactance mean value of the power system. One small impedance branch is changed into two branches with relatively high impedance through series compensation, so that the convergence of power flow calculation can be improved. The small impedance branch with any impedance or even the branch with zero impedance can be calculated. According to the power flow calculation method, the problem of convergence due to the fact that a small impedance branch-containing branch system is analyzed by a conventional power flow calculation method employing the fast decomposition method can be effectively solved, and meanwhile, power flow calculation can be carried out on a normal system. Therefore, adverse effects are avoided.