Research on Power Flow Calculation Method for Multi-voltage DC Distribution Network Considering Different Connection Modes

The power flow analysis of the DC distribution network is the basis of the design, operation and maintenance of the DC distribution system. Traditional DC power flow calculation methods cannot meet the power flow calculation requirements of multi-voltage DC power grids with more flexible control methods, more diverse operating modes, and richer load types. To this end, this paper proposes a power flow algorithm for multi-voltage DC distribution networks under different wiring modes. First, consider the multiple control methods of AC/DC converters and DC/DC converters, and establish a unified power flow control equation. Secondly, it studies the power flow calculation models of AC/DC converters and DC/DC converters in different connection modes, and focuses on the analysis of the power flow equation construction methods of different types of DC loads in true bipolar and pseudo bipolar networks. Furthermore, the steps and methods for solving the unbalanced network power flow equation are given. Finally, the demonstration project of the VSC multi-voltage DC distribution network at both ends of Suzhou is taken as an example to verify the effectiveness of the multi-voltage DC power flow algorithm proposed in this paper under different control methods. © 2021, Power System Technology Press. All right reserved.