Open-source short-circuit current solver for power systems with renewable energy sources and HVDC links

• Models considering fault characteristics of renewable energy sources (RES), HVDC and other devices are created. • An equivalent impedance calculation method without adding new bus is proposed for the transmission line fault. • Iterative short-circuit current calculation integrates RES and HVDC. • Open-source short-circuit solver implements proposed models and methods with additional useful features. Large-scale integration of renewable energy sources (RES) and high voltage direct current (HVDC) links have changed the power system short-circuit current (SCC) level significantly. Traditional SCC solvers for systems dominated by synchronous generators are no longer applicable. This paper provides an open-source SCC solver based on Simulation Toolkit for Electrical Power Systems (STEPS). It supports SCC analysis for power systems with RES and HVDC and allows customized extensions for emerging RES and HVDC control models. In the solver, the sequence models are created for RES and HVDC to support the research on changes in SCC characteristics. To speed up the calculation of equivalent impedance for different fault locations, a new method without adding new bus at the fault location is proposed. The solver provides iterative SCC calculation and direct solving functionality with a range of additional features. Flexible options are provided and configurable to cope with different calculation scenarios. The accuracy of the SCC solver is compared with PSS/E. Meanwhile, numerical examples considering RES and HVDC links are provided to demonstrate the practicality of the solver.