Energy Function for Power System With Detailed DC Model: Construction and Analysis

An energy function for AC/DC power system represented by a structure-preserving model is proposed considering detailed DC dynamics. The generators are described by one-axis model with excitation control. The DC line is modeled in details as load dependent on converter bus voltage and DC line current. The effects of mode shift and voltage dependent current limiter (VDCOL) are taken into account. The proposed energy function is theoretically shown to meet the major requirements of being an energy function. A numerical algorithm for constructing the energy function is presented. The monotonic decreasing property of the proposed energy function is numerically demonstrated on two AC/DC systems. It is clarified that the proposed energy function can be viewed as a generalization of the existing energy functions with less assumption.