| With the continuous development of social economy,the structure of power grid in China is undergoing great changes.On the one hand,the widespread access of distributed energy sources such as photovoltaic and wind power has changed the power flow distribution of the power grid,which has a huge impact on the power supply stability of the ac system.On the other hand,under the condition of rapid economic development,the national electricity load increases rapidly,and the burden of the original distribution network increases.Dc load is widely used,and ac/dc conversion is needed to connect to the power grid,which reduces the power supply efficiency.In this paper,a typical dc power distribution system is designed.Considering economy and power supply stability,the appropriate voltage level,topology and connection mode are selected.Then the typical components in dc distribution system,such as voltage source converter,dc transformer,photovoltaic cell and energy storage system,are studied and the corresponding control system is designed.Then,the PSCAD simulation software is used to build the dc distribution system model at both ends,and the simulation verification is carried out for the steady-state operation,energy storage charging,load fluctuation and mode switching of the system,so as to verify the power supply stability.Finally,the typical dc line fault and its protection principle of dc distribution system are analyzed theoretically,and the simulation verification is carried out by PSCAD simulation software. |
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