Comparative Assessment of Shifted Frequency Modeling in Transient Stability Analysis using the Open Source Simulator DPsim

Modern power systems introduce new dynamics, which may require the appropriate selection of the modeling method for each type of dynamic simulation. In this paper, electromagnetic transient (EMT), Root Mean Square (RMS), and Shifted Frequency Analysis (SFA) modeling are compared in the scope of the dynamic simulation of transient stability analysis. The comparison is carried out by analyzing the accuracy of the simulation results as a function of the simulation step size. The evaluation is conducted for classic and low inertia systems for the accuracy of rotor angle transients and the critical clearing time, being the variables of interest in transient stability analysis. The real-time open source simulator DPsim is employed. The main advantage presented by DPsim, is the possibility to run the same simulation scenario with the same solver, but in three different modeling domains. This powerful feature enables a systematic comparison between the modeling methods. With respect to transient stability analysis, the results of the comparative analysis support the usage of SFA, both for classic and low inertia systems. SFA incorporate more dynamics than RMS simulation into the models, while at the same time allowing larger step sizes than EMT simulation.