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Electric hydraulic interaction
Norwegian University of Science and Technology, Faculty of Information Technology, Mathematics and Electrical Engineering, Department of Electrical Power Engineering.
2011 (English)MasteroppgaveStudent thesis
Abstract [en]

The hydraulic models representing hydro turbines and conduit system found in standard model libraries of power system analysis tools are often simplied mod- els. Subsequently, important information about the dynamics of the hydraulic system may not be properly represented by such models, putatively resulting in insucient representation of the interaction between the electric system and hydraulic system. In this master thesis three dierent hydraulic models for hydro power plants equipped with Francis turbines for use in power system simulation software has been studied: 1) a simplied model often found in power system simulation tools; 2) a model including a surge tank and elastic water column and 3) a model that includes a surge tank, elastic water column and turbine parameters accounting for the characteristics of the hydraulic turbine. The hydraulic models were implemented in Simpow, a power system simulation tool. A frequency scan in the range from 10􀀀3-5 Hz was performed. The re- sults were compared with a frequency scan from LVtrans, a program specically designed for accurate simulation of the dynamics of the hydraulic side in hydro power plants. The comparison showed that the simplied model failed to prop- erly represent the dynamics of the conduit system. The the model with surge tank and elastic water column was able to represent the dynamics of the con- duit system with satisfactory accuracy. Best representation was achieved for the model including turbine parameters. The three hydraulic models were implemented in three dierent power system congurations: a single machine innite bus system; a system consisting of two interconnected areas; and a system that has sustained power oscillations. The resulting active power delivered from the generator were the hydraulic models was implemented, the speed of the turbine, the pressure at turbine and the ow through the turbine were investigated. The simulation results revealed that the active power variation from the gener- ii ators is in the same range for all three models, except for the simulation with sustained power oscillations. The speed variations of the turbine as a result of incidents in the electrical network are in the same range for all three models. The model including turbine parameters is the only model able to represent the pressure variation as a result of a variation of speed of the turbine. For power oscillations with frequencies equal to the half period frequency of the water hammer eect,1.38Hz, both the model with surge tank and elastic water column and the turbine parameter model show very little response. For frequencies equal to the water hammer eect, 0.69Hz the variation in ow is also small for the two models. In general, the model with turbine parameters are better damped than the two other models. Further work should include development of an automated routine for determin- ing parameters to use in the model with turbine parameters as well as investiga- tions of how the model behaves in dierent network congurations.

Place, publisher, year, edition, pages
Institutt for elkraftteknikk , 2011. , 69 p.
Keyword [no]
ntnudaim:6268, MTENERG energi og miljø, Energibruk og energiplanlegging
URN: urn:nbn:no:ntnu:diva-14045Local ID: ntnudaim:6268OAI: diva2:445816
Available from: 2011-10-05 Created: 2011-10-05

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