## 4 Results and Discussion

Table 3: \(\mathrm{R_{yy}}\), RMSE, and \(\mathrm{R^{2}}\) coefficients of obtained SI algorithm using BJ and comparable generator. Figures 8 and 9 compare the responses of a traditional generator and the SI algorithm in an electrically relatively close three-phase short circuit in a 330 kV overhead line and an electrically relatively far three-phase short circuit. The response of a traditional generator to a short circuit was modeled in the PSS/E packet and captured the frequency, generator power, and busbar voltage. In the mathematical model of this generator, the deadband of the turbine governor is relatively large, i.e., the turbine governor does not work during the transient process. The Automatic Voltage Regulator (AVR) system was activated and modeled. Subsequently, the developed SI algorithm was modeled with the Simulink software package, and frequency change, modeled with the PSS/E, was fed to the input of the SI algorithm in the Simulink. Figure 8: Comparison of active power outputs of the SI algorithm and simulated power output, when H = 5 s and 3 ph short circuit (SC) in the overhead line is far away (in the middle of power system) from the generating source with the SI algorithm. Figure 9: Comparison of active power outputs of SI algorithm and simulated power output when H = 5 s when 3 ph short circuit (SC) in the overhead line is close to the generating source with the SI algorithm. We observed a transient process (Figure 8) in which the three-phase short circuit is electrically distant from the traditional generator, and then, the voltage at the generator terminals does not drop due to the AVR system, and the rotor angle increases in terms of the stator magnetic field. Due to a short circuit in the grid, voltage decreases; therefore, an excitation system is activated that tries to restore the voltage at the generator terminals, i.e., the exciter increases the current. This is the reason why the traditional generator increases active power at the initial short circuit time. In this case, SI algorithm behavior is superior to the traditional generator, because the SI algorithm decreases the active power at the initial short circuit time. Most likely, such SI algorithm behavior will help to reduce generator oscillations during the transient process. The behavior of the SI algorithm from 0.9 s is analogous to that of a synchronous generator. We see that, in the case of a short circuit (Figure 9), the SI algorithm decreases the power at the initial time and only disconnects the short circuit after 140 ms; the power starts to increase, and the transient process settles approximately in 5 s. This operation of the SI algorithm is superior to the generator in that it delivers active power to the electrical power grid at the initial short circuit time, thus increasing the stability of the electrical power grid. In this case, the traditional generator starts to decrease the power at the initial short circuit time, because the short circuit is electrically close (only by the transformer); therefore, the voltage at the generator terminals is significantly reduced because the resistance approaches zero, and due to the magnetic processes in the generator, the current stops increasing when a certain value is reached, meaning that the active power supplied to the electrical power grid by the traditional generator decreases. The type of inverter and its characteristics (current or voltage source) may affect the performance of the SI algorithm.