Gauss-Seidel three-phase load flow calculation method applied to un-grounded distribution network

The invention relates to a Gauss-Seidel three-phase load flow calculation method applied to an un-grounded distribution network, belonging to technical field of distribution network dispatching automation. Firstly, a relational expression between three-phase voltage and three-phase current of each node in the un-grounded distribution network is obtained according to the three-phase voltage and the three-phase current of each node in the un-grounded distribution network, in the relational expression, the voltage constraint on the second side of a three-phase transformer connected with a high voltage distribution network and a medium voltage distribution network in the un-grounded distribution network is added, then the relational expression is expressed into a form of partitioned matrix, and finally, a Gauss-Seidel three-phase load flow calculation formula of the un-grounded distribution network is obtained according to the relational expression in the form of partitioned matrix. By adopting the method of setting a zero sequence voltage reference value, the problem of difficulty in convergence on three-phase load flow calculation of the un-grounded distribution network caused by the floating zero sequence voltage in a distribution network of which neutral points are not grounded is solved. The Gauss-Seidel three-phase load flow calculation method has very good convergence and very high engineering practicability.