Abstract : With the grid connection of distributed generation, PQ, PV, and slack node models can no longer meet the requirements of power flow calculation. This paper analyzes the output characteristics of three distributed generation grid connection methods: synchronous machines, asynchronous machines, and inverters. A P0 node model is defined, which changes the original power flow equations and affects the convergence of power flow calculation. Therefore, optimal multipliers are introduced to correct the Jacobian matrix, improving the convergence performance and speed of the Newton-Lambert method. Simulation calculations are performed on various operating modes of a power grid in a certain region. The results show the adverse effects of the introduction of distributed generation on power flow calculation and verify that optimal multipliers can improve the ill-conditioned power flow problem caused by the P0 node model. Keywords : Distributed generation; P0 node model; Optimal multipliers 1. Introduction With economic development, the grid capacity is increasing, and the hidden dangers of large power grids are becoming increasingly prominent. For example, the large-scale power outage in southern China caused by the snowstorm disaster in 2008 and the "8.14" blackout in the United States in 2003 illustrate this point. In these incidents, small-capacity distributed generation (DG) sources played a significant role, crucially supplying power to critical loads and restoring the power grid. Therefore, DG as a supplement to the large power grid is a current trend in power development. While the large-scale grid connection of DG is a beneficial supplement to the large power grid, it also brings many negative impacts and increases the difficulty of grid analysis. This paper mainly analyzes the impact of DG on regional power grid power flow calculation and studies the modification of the Newton-Raphson method to solve the power flow calculation problem in regional power grids containing DG. Although a node model of DG has been established in the literature, it is not perfect and uses a multi-iteration approach, resulting in a linear convergence speed, failing to fully utilize the squared convergence speed of the Newton-Raphson method. This paper establishes a node model of DG and uses the optimal multiplier modified Newton-Raphson method to solve the ill-conditioned power flow problem caused by DG. (Full text of the method for calculating power flow in regional power grids containing DG is available for download.)