2. Model system
For the simulation of the transient stability, the IEEE nine bus power system model shown in Fig. 1 is used. The model system consists of two generators (G1 and G2) with capacities of 200 MVA and 130 MVA, respectively, and an infinite bus. Generators are connected to one another through transformers and double circuit transmission lines. The line parameters have the form R + jX (jB/2), where R, X and B represent resistance, reactance and susceptance per phase with two lines, respectively. F1, F2 and F3 are considered as fault positions. SVCs (SVC 1 and SVC 2) are connected in shunt at the bus of generators G1 and G2. Various generator parameters as well as the automatic voltage regulator (AVR) and governor (GOV) control system models used in this simulation are given in