Olkiluoto 3 disconnected from the grid in a fault ride-through test
As a result of the fault ride-through test conducted by Fingrid on 29 November 2023, Olkiluoto 3 disconnected from the main grid. The test arrangement was successful on Fingrid’s part. The cause of the disconnection is being investigated at the power plant. The power system is functioning normally.
The reliable operation of power plants during faults occurring in the main grid can be verified by conducting a so-called fault ride-through test. The test involves creating a momentary short circuit in the grid near the power plant, thus causing a similar drop in voltage that would occur in the event of a real fault resulting from, for example, a lightning strike in the vicinity of the power plant.
Olkiluoto 3 is the largest individual power plant unit in the Finnish and Nordic power system. In terms of the functionality of the entire power system, it is important to ensure that the power plant operates stably and reliably in various situations, including faults in the grid. For this reason, Fingrid arranged a separate fault ride-through test to ensure the reliability of Olkiluoto 3.
For the fault ride-through test of Olkiluoto 3, Fingrid changed the switching of the main grid in Western Finland so that the effects of the test on others connected to the grid were minimal. Due to the abnormal switching state, it was necessary to limit the volume of wind power production on the west coast during the test.
Olkiluoto 3 disconnected from the main grid during the test. An investigation into the causes of the incident has been initiated at the power plant.
Tuomas Rauhala, Senior Vice President, Fingrid Oyj, tel. +358 40 506 4695
Minna Laasonen, Fingrid Oyj, tel. +358 303 955 132
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