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The Result
■ Innovative reuse of a deactivated power plant
■ Improved grid stability due to the generation of reactive power and short circuit power through conversion of the generator into a synchronous condenser
■ Low investment and operational costs
SPPA-E3000 Converting power plants to synchronous condensers enables the innovative reuse of the Ensted deactivated power plant to ensure electricity grid stability in Denmark.
The Plant
Commissioned in 1979, the former steam power plant Ensted ENV3 (Enstedværket) is located at the head of Aabenraa Fjord in the south of
Denmark. Its Unit 3, formerly fired by coal and oil, had been Denmark’s largest combined heat and power unit. Ensted was equipped with a total electrical capacity of 626 MW and a heat capacity of 76 MJ/s. The operator, DONG
Energy A/S, had mothballed the power production by 1 January 2013 due to expected lower electricity consumption and a rising share of energy production from renewable sources, mainly wind power plants.
The Task
As already 39% of Denmark’s energy is supplied via wind power, conventional power plants with rotating equipment are being increasingly discontinued. To ensure grid stability, the existing Ensted plant was to be converted to a synchronous condenser. Moreover, the project had to be executed within a very tight schedule.
involved the turnkey solution SPPA-E3000 which was seamlessly interfaced into the existing
SPPA-T2000 system. The Ensted power plant now contributes to the stability of the national
Danish electricity grid when required.
Siemens was also responsible for the mechanical refurbishments, dismantling and conversion of the turbine, sensor systems, hydraulic components and adaption of the control system.
The rebuilding of the Ensted plant was associated with low investments and low risks:
Components from the original manufacturer, the reuse of equipment and the smooth integration of the new solution SPPA-E3000 were conducted with minimal effort.
Due to the extensive know-how and experience of the project team and Siemens’ professional project management capability, the project was completed within the very narrow, challenging timeframe of five months.
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Our Solution
Siemens had already successfully rebuilt existing power plants, similar to Ensted, into synchronous condenser mode.
Such compensators are generators which are connected to the grid without being driven by a turbine. They produce reactive power depending upon the excitation applied, thereby stabilizing the high-voltage grid.
Furthermore, the condenser mode enables the generator to deliver short circuit power to the grid and provides the opportunity for voltage regulation.
As the main contractor, Siemens executed the major part of the project. The electrical scope
Leif Høgh Sørensen, Project Manager
DONG Energy Thermal Power A/S

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