EDG9 auxiliary diesel generator is quite a big engine

The EDG9 diesel generator which serves as an auxiliary power source for power plants Olkiluoto 1 and Olkiluoto 2 is quite a big engine. At first sight it appears to be just a regular diesel generator, but it has a very special purpose and is significant to Teollisuuden Voima's elctricity production.

As a whole, the Emergency Diesel Generator (EDG) renewal project is the largest modernisation project in the history of OL1 and OL2. Not only will it secure the operation of the plants, it also provides employment to Finnish professionals for years to come. The diesel generators are designed to secure electricity supply to the power plant in case of a possible but improbable loss-of-power situation.

The project was launched in 2007 and the contract was awarded to Wärtsilä in 2013 after six years filled with engineering work and studies. The existing auxiliary diesel generators, eight in total, will be replaced in the project with new diesel generators which are erected in the same places as the old ones. The project is carried out in such a way that eight generators are available for operation at all times. To ensure this, a ninth diesel generator was built to take the place of the old generators, one at a time, as they are replaced during power operation. Now that the ninth EDG is ready, the replacement of the original diesel generators will start towards the end of the summer 2020. The replacement of one diesel generator takes about six months.

The project was launched in 2007 and the contract was awarded to Wärtsilä in 2013 after six years filled with engineering work and studies. The existing auxiliary diesel generators, eight in total, will be replaced in the project with new diesel generators which are erected in the same places as the old ones. The project is carried out in such a way that eight generators are available for operation at all times. To ensure this, a ninth diesel generator was built to take the place of the old generators, one at a time, as they are replaced during power operation. Now that the ninth EDG is ready, the replacement of the original diesel generators will start towards the end of the summer 2020. The replacement of one diesel generator takes about six months.

The cost estimate for the whole modernisation project is more than one hundred million euro and the project will go on for many years. The main supplier is Wärtsilä Finland. Wärtsilä is also responsible for regulatory documentation, design, the main equipment, erection and commissioning. TVO is in charge of works related to construction engineering and HVAC systems, and has awarded related contracts to e.g. Skanska, Vesi-Vasa, Vertek and Ilmastointi Salminen. The new diesel generators to be erected at the plant units will be equipped with air cooling, in addition to seawater cooling, and they are of seismically resistant design.

Each diesel generator is ready for operation at all times and will reach the full operating speed in less than 10 seconds on a start-up command. The replacement of the diesel generators takes place at the plant units during power operation.

EDG 9 is a completely new diesel power plant and had its first start-up on 8 May 2020. The EDG 9 plant building is 15 metres wide and 20 metres long, and with three storeys stands at a height of more than 10 metres. The diesel generator itself is quite a big engine (4 m x 3 m x 9 m) and weighs more than sixty-eight thousand kilograms. It features six cylinders, and the pistons have a diameter of 32 centimetres. The speed of the engine is 750 RPM and the generator's power output is more than 2300 kilowatts.

For TVO, the project has been headed by Seppo Hyvärinen, Mari Hovi and Ossi Heikkinen before the current Project Manager Petteri Salminen.

Text: Pia Petäjä

Photo: Helena Urpulahti