Power flow approximation for DC networks with constant power loads via logarithmic transform of voltage magnitudes.

• A linear power flow of dc grids via a logarithmic transformation is presented. • Linear power flow methods allow improving convergence times in repetitive routines. • Logarithmic transformation of voltage magnitudes (LTVM) provides a graphical interpretation of the Taylor-based methods for power flow analysis. • Radial and meshed networks with multiple generation sources can be analyzed in the LTVM approach. • Power flow analysis is an essential tool for planning and operating electrical networks. This paper proposes a logarithmic transformation of voltages (LTVM) for the power flow in DC grids. This problem is non-linear due to the presence of constant power loads (CPLs), which also introduce a negative resistance effect that can create numerical instability for conventional algorithms. The proposed methodology is applied to dc-microgrids, dc-distribution and multi-terminal high voltage DC transmission (MT-HVDC). Two main approximations are presented and compared in terms of computational performance and the accuracy of the solution. Simulation results performed in Matlab/Octave demonstrate the advantages of the proposed methodology using a complete set of test systems, from low to high voltage applications. The proposed methodology does not require any consideration about the topology of the grid (radial or meshed) or the number of constant power loads. [ABSTRACT FROM AUTHOR]