This report describes a first phase of effort in providing the Bonneville Power Administration (BPA) with comprehensive tools for model-based analysis of interactions between the Pacific HVDC Intertie (PDCI) and the alternating current (ac) system containing it. The work builds upon the transient stability model coded by Control Technologies, Inc. (CTI) for use in the Electric Power Research Institute (EPRI) Extended Transient-Midterm Stability Package (ETMSP). The general thrust of the effort is that CM`s model be interfaced to and tested against all tools provided by EPRI`s Power System Analysis Package (PSAPAC), and that these tools be used to investigate options for PDCI use in testing and control of western system dynamics. This will require refinements to the tools, the model, and western system case data. The PSAPAC tool for eigenanalysis is the Small Signal Stability Package (SSSP), useful for performing modal analysis of the multiterminal HVDC (MTDC) system. Such analyses are necessary to design and test an expanded role of the PDCI for power system control. This study focused on testing the application of the MTDC with SSSP. Modifications were made to enable SSSP to read the MTDC model. The PSAPAC and SSSP tools and the MTDC model were evaluatedmore » for accuracy and consistency using several modal analysis techniques, including Prony analysis on ETMSP-generated data. Although SSSP appears to be useful in analyzing the PDCI modes, inconsistencies limit the overall usefulness of that approach. The modal frequencies and damping identified by SSSP are inconsistent, indicating SSSP has difficulty analyzing the MTDC representation of the dc systems. The differences between the new and existing models can be used to identify the particular modeling issues associated with SSSP which are presently resulting in inconsistent results.« less