Research on power flow calculation method of three-phase unbalanced microgrid based on time-domain iterative method

This article proposes a three-phase unbalanced microgrid power flow calculation method for the distributed generation (DG) unit based on time-domain iteration concept and the introduction of symmetric component analysis. Firstly, the discrete operation model of sag control DG unit is established, and the output power of DG unit is calculated using time domain derivation instead of equations to avoid convergence problems. Secondly, the unbalanced three-phase three-wire system is decomposed into independent positive and negative sequence network based on the symmetric component method, and the feeder and load model of the positive and negative sequence network are established according to the network connection and network parameters. Then, the parallel iterative calculation of the positive and negative sequence complete network model is derived, which does not need to update the network matrix and reduces the scale of calculation. Finally, the algorithm is simulated based on IEEE-8 node system verify the effectiveness of the algorithm.