A numerical integration method for long‐term power system dynamic simulation

Large power system frequency/voltage fluctuations due to severe faults in trunk transmission lines or major generating units may trip‐off other facilities and result in large‐scale power system blackout. To prevent such blackout, development of an accurate and fast long‐term power system dynamic simulation tool is required. With respect to the development stage, selection of a numerical integration method available for step‐size adjustment, and the development of a scheme for the adjustment are principal subjects. The trapezoidal and the second‐order Gear methods were selected as possible candidates for the step‐size adjustment from the viewpoint of numerical stability. The trapezoidal method is selected from the viewpoint of accuracy and applicability to power system dynamic simulations. A new scheme for the automatic step‐size adjustment is proposed for the trapezoidal method to achieve fast simulation of the long‐term power system dynamics. The validity of the proposed scheme is verified through simulation studies on a single‐machine‐to‐infinite bus system.