Temporary Overvoltages during Field Tests of System Restoration after Blackout: Analysis of the Phenomenon and Possible Countermeasures

E. Cinieri, M. Sforna, A. Carrus, and F.M. Gatta (Italy)


Blackout, System Restoration, SystemSecurity, Ferroresonance overvoltages.


In order to gain experience in the operations that are necessary to guarantee quick restoration of the power system after a blackout, a reenergization test from the hydro power plant of Roncovalgrande in blackstart, was performed in Italy. The line Roncovalgrande-Turbigo was energized from the 420 kV busbars of Roncovalgrande power plant in order to supply energy and enable restarting of the thermal power plant of Turbigo. During the test high temporary overvoltages arised. The research work performed has enabled comprehension of the causes of the phenomenon and has drawn to identify the countermeasures that are necessary to avoid it and assure succesfull accomplishement of the operation.

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