The utility model provides an electric power switching device is joined in marriage to direct current for improving rural power grids three -phase balance and capacity, does include AC DC converter, first energy storage unit, power flow controller, second energy storage unit, DC AC converter, customer side the?DC?load and switch board. AC AC?electric network is connected to the interchange side of DC converter, AC the input of first energy storage unit is connected to the direct current side of DC converter, power flow controller is connected to the output of first energy storage unit, and power flow controller passes through direct current line connection second energy storage unit, is DC connected respectively to the output of second energy storage unit the direct current side and the customer side the?DC?load of AC converter, DC the interchange side of AC converter exchanges output for the three -phase four -wire. The utility model discloses under the prerequisite that does not change original middle and low voltage ac distribution network infrastructure, adopt DC distribution, form the interchange the direct current (Exchange) the power supply structure, solved in because, low pressure line power supply radius overlength, three -phase unbalanced load and a large amount of end user voltage quality subalternation problems that arouse that insert of distributed generator.