A unified power flow approach using VSC-efficiency for AC-DC distribution systems operating at grid connected and islanded modes

Abstract This paper presents a unified power flow formulation for grid-connected and islanded distribution systems with any desired AC-DC structure. Load flow equations are formed using the generalized matrices. The definition of these matrices is based on graph theory and includes network structure and data of the lines, loads, power sources, converters, and efficiency of converters. The efficiency of the converters is modeled in the load flow program as a function of its operating current. By simulation in PLECS software, the efficiency curve of the converter is obtained. The proposed method is implemented on several AC-DC case studies in islanded and grid-connected operating modes. The results show that the proposed formulation of power flow simply considers the actual efficiency of the converter in the calculations and has less computational time than the available methods.