Elimination of floating nodes for load flow calculation

Most approaches aiming at reduction of the power flow computation time approximate the Jacobian matrix. Thus, the convergence is degraded compared to the conventional Newton method. This paper proposes a new approach for reducing the processing time by considering the fact that half of the nodes in real power systems are floating nodes that can be removed. In the conventional reduced matrix approach where the floating nodes are removed, the sparsity is lost. The method in this paper does not remove all of the floating nodes but keeps some nodes by using an optimal criterion for keeping the sparsity. The criterion is to indicate the minimum number of elements in the reduced matrix. This method has been applied to a 1000-node test system. It was verified that the number of elements of the Jacobian has been reduced to about one-half that of the conventional matrix. And computation time has been remarkably improved without sacrificing the convergence characteristics for the power flow computation.