SUMMARYThe electric power industry has undergone considerable changes in the past decade throughout the world. The essential feature of these changes is to promote competition among utilities and to form active power market with reliable and less expensive electricity. Under these circumstances, stabilization and voltage stability problems of power systems are very important. Power systems engineers are examining the effect of the resistance value of braking resistors and the timing of their insertion on the improvement of the stability level.In this paper, we report on experiments carried out on the optimal size and switching of braking resistors, shunt capacitors, and other auxiliary devices. The experimental system model consists of a single synchronous generator connected through two parallel transmission lines to an infinite bus.

Keywords: transient stability, braking resistor, equal area criterion for stability, single machine infinite busThe electric industry has undergone a considerable change in the past decade throughout the world. The feature of change is to promote competition among utilities and to form active power market with reliable and less expensive electricity. Under these circumstances, stabilization and voltage stability problems of power system are very important. The power systems engineer is investigating the effect of the capacity of the braking resistor and the timing of insertion for the improvement of the stability level.In this paper, experiments are carried out the optimal size and switching of braking resistor and shunt capacitor etc. The studied system model for experiments consists of a single synchronous generator connected through two parallel transmission lines to an infinite bus. Figure 1 illustrates the exprerimental single machine infinite bus system A braking resister (system damping resistor) is installed at the generator terminal. SW1 and SW2 are used for interupption of one of the power transmissions. A shunt capacitor are may be used for the performance improvement by supporting the terminal voltage during the fault.Critical power transmission capability is the most consern f research, which are compared with numerious convinations of amount and insetion time of breaking resistor. Figure 2 illustrates these relationship and the maximum power will be 0.4 pu.Power consumuption by a braking resistor is also important in Fig. 1. Single machine infinite bus system order to decide the installed capacity withstands themal increase. This topic is also discussed with the above-mentioned experiments as shown in Fig. 3. As a conclusion of this study, a braking resistor is proved as a simple method to improve power stability. Combination of a shunt capacitor also provides a improved performance.