Study on methods for solving the divergence of power flow with small impedance branches

Small impedance branches may lead to divergence of power flow. The convergence of power flow can be improved by some methods, such as improving voltage start, improving the Jacobian matrix, and using fast decoupled power flow. This paper investigates these methods, and finds out that when these methods are applied to systems with small impedance branches, they possess same characteristic, that is the Jacobian matrices of the equations of all these methods are almost same, but the right-hand vectors are different. That means the Jacobian matrix has great influence on the convergence of power flow, but the right-hand vector or the calculated power has little influence. And this conclusion explains why all these methods which are much different in principle are efficiency in dealing the divergence problem induced by small impedance branches. Experimental results validate our analysis.