Page 206 - Hybrid-Renewable Energy Systems in Microgrids

186 Hybrid-Renewable Energy Systems in Microgrids

From simulation results, it is obvious that the system is not stable when a long
transmission line is used without considering SDBR. However, SDBR can signifi-
cantly augment the transient performance of a grid connected WTGS.
This is because during the short insertion period of SDBR, energy is dissipated and
it increases the terminal voltage of IG. Therefore, SDBR has the ability to mitigate
destabilizing depression of electrical torque and contribute to the balance of active
power and improves system transient performance.

2.5.2 Effect of shaft stiffness

Figs. 9.27–9.30 show transient responses of the system with and without SDBR for
different values of shaft stiffness. In the simulation, two values of shaft stiffness is
considered (K s = 0.8 pu and X t = 0.1 pu). Electrical torque, stator voltage, generator

Figure 9.26 Turbine speed response.

Figure 9.27 Electrical torque response.