Effect of Penetration of Wind DGs on Transient Stability of Captive Power Generation Units

Abstract

This paper presents the analysis of transient stability for industrial generators and the effect of distributed generator units on transient stability has been studied. Here we considered IEEE 39 busses system having one utility bus and 9 captive generation units. It is observed that the voltages at all the buses, decreased when Wind Power DGs are connected. Voltages at all the buses in the system are reduced because of reactive power demand by Induction Generators. The total load of the system is 121.57 MW + j 56.6 MVAr. Critical Clearing Times (CCTs) are obtained without introducing any DG and later, CCTs are obtained with four Wind Power DGs. Their capacities are 7.0 MW, 8.0 MW, 9.0 MW and 5.0 MW with 0.8, 0.85, 0.9 and 0.95 power factors respectively. The Induction Generators used in Wind DGs inject active power and consume reactive power. It is observed that the voltages at all the buses, decreased when Wind Power DGs are connected. Voltages at all the buses in the system are reduced because of reactive power demand by Induction Generators. LLLG faults at seven load buses and nine Generator buses and are considered for obtaining Critical Clearing Times (CCT). It is observed that transient stability of system is improved by placing DGs. DGs used in this system improves the critical clearing time (CCT) for faults at load buses by 30% and faults at generator buses by 15.5%. The detailed results are tabulated in this paper.