Power System Toolbox Updates to Enable Long-Term Variable Time-Step Dynamic Simulation

Power System Toolbox (PST) is a MATLAB-based power system transient stability simulator package. In this paper, we report updates to PST that facilitate the study of long-term dynamics (LTD). Most importantly, the differential-algebraic equations that form the basis of the non-linear power system simulation routine have been functionalized and arranged such that any MATLAB, Octave, or custom ODE solver can used. This enables the application of variable time-step solvers which can reduce execution times for long simulations up to 14 times previously possible with PST. Additionally, new models have been developed and incorporated into PST that allow for automatic generation control (AGC) and user defined power injection models. With these updates, PST becomes suitable for the study of LTD issues such as frequency response during significant wind or solar ramps and the associated governor and AGC interactions. Examples showing some use cases and simulation speed ups are presented in this paper. The original software package (PST 3.0), and the updates pertaining to PST 4.0 are publicly available through an MIT open source license.