IMPACT OF WIND ENERGY CONVERSION SYSTEMS ON GENERATOR DISTANCE PHASE BACKUP PROTECTION

Abstract

The need for clean, renewable energy has resulted in new mandates to augment, and in some cases replace conventional, fossil based generation with renewable generation resources. Wind generation is among those resources that have been at the center of attention. These resources are environmentally friendly, renewable, and they do not produce green-house gases. Therefore, there has been a significant growth in the integration of wind power into power systems networks in recent years. This structural change in power systems results, however, in new concerns regarding the reliable and secure operation of the power system with high penetration of wind energy conversion systems. This thesis investigates the impact of large doubly-fed induction generator- and full- frequency converter-based wind farms on the performance of generator distance phase backup protection (Relay (21)) and the generator capability curves. In this context, comprehensive studies are conducted on a sample power system incorporating large DFIG- and FFC-based wind farms tapped to the transmission system. The results of these studies which provide an in-depth assessment of Relay (21) performance in the presence of this type of wind energy conversion systems show that a wind farm tapped to a transmission line has an adverse effect on the distance phase backup protection of a nearby generator. The severity of such an impact varies according to the fault type and its location. Moreover, the adverse effect of the wind farms on Relay (21) performance extends to affect the coordination between generator distance phase backup protection and the generator overexcited capability limits. Such an impact varies also according to the fault type, fault location and generator loading. The time-domain simulation studies are carried out using the ElectroMagnetic Transient Program (EMTP/RV).