Abstract: | 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. |