Convergence problems in forward/backward sweep power flow algorithms may arise because of neutral grounding resistance in multi-grounded three-phase four-wire distribution networks. The causes of the convergence problem are analyzed and an impedance compensation method of addressing this problem is described. The proposed method is able to guarantee the convergence and keep the power flow solution unchanged. By adding two serial impedances with opposite value between the grounding resistance and the neutral point

the spectral radius of the Jacobian matrix in fixed-point iteration is reduced to below 1

which satisfies the requirement of contraction mapping. Finally

the results of numerical tests have demonstrated the correctness of the method and its practical values. This work is supported by National Key Technologies R&D Program of China (No. 2013BAA01B01) and Important Guizhou Science & Technology Specific Projects (No. (2012)6022).