Impact of large scale wind power integration non Ethiopian power system transient stability

Abstract

Ethiopian power system is a hydro dominant system where 84.19% of the electricity generation is hydro based. But in recent year Ethiopia electric power corporation is using wind power to solve electric power shortage. Currently 14.07% (153MW from Adama II wind farm, 120MW from Ashegoda wind farm and 51MW from Adama I wind farm) of the country’s power is generated from wind. Integrationoflargescalewindfarmintoapowersystempresentssomechallengesthatmust be addressed, such as system operation and control, stability and power quality. Therefore, currently several wind impact studies have been carried out in different countries. From these studies it was understood that the level of wind power penetration and intermittent nature of wind have major impact on a power system. This study focuses on the impact of wind power integration on the transient stability performance of a power system and different scenarios have been investigated. The analysisandmodelinghasbeendoneusingDIgSILENTsimulationsoftwarebasedondata obtained from EEP and Adama II wind farm. A very large wind power plant may contain hundreds of Megawatt-size wind turbines. These turbines are interconnected by an intricate collector system. While the impact of individual turbines on the the larger power system network is minimal, collectively, wind turbines can have a significant impact on a power system during a sever disturbance such as nearby fault. since it is not practical to represent all individual wind turbines to conduct simulations, a simplified equivalent representation is required . In this study, Adama II wind farm is aggregated from 102 wind turbines to single turbine representation and the model developed has been verified for its accuracy. The simulation has given 0.066% (0.1 MW)of active power flow and 0.081% (0.04 MVAR) of reactive power flow difference between full turbine representation and single turbine representation of Adama II wind farm. The transient stability impact has been analyzed for different aspects like location of fault and generator technology. As per the result of this study, wind power integration has a positive impact on the the critical fault clearing time (CCT) of the power system for example, for a fault near to Ashegoda wind farm the CCT of Tekeze power plant has been improved by 226 ms and for a fault far from any of the wind farms the CCT has been improved by only 44 ms