Frequency stability in integrated synchronous power systems

Abstract

In the later years, the frequency quality in the Nordic synchronous system has been reduced significantly. In order to restore the frequency quality, new requirements for the primary frequency control (FCR) is under development by the Nordic TSOs. The new FCR requirements based on stability and dynamic performance have been tested for a single unit in Sundsbarm power plant and for a single unit in Hjartdøla power plant. Simulation models was build up to mirror the behaviour of the power plants during the tests. The new stability requirentent for syncronous operation is similary to the FIKS stabiltiy requiremnt for seperat operation. However, the 'system' that regulates against is different. It is desired that the providing unit should deliver steady-state power within 5 seconds at disturbances. Results from the tests, showns that the hydropower units fullfil the stability requirements. The tests expose also that the hydropower units can deliver 100% steady-state power response within 5 seconds. Except for the unit in Hjartdøla power plant tested with 4% droop setting which can deliver 91% of full steady-state response at downwards regulation.