MSc. Antti-Juhani Nikkilä studied the performance of the electricity transmission network in case of power system blackouts. In such blackouts, a country or even multiple countries could be without electricity. The objective of the thesis was to study new procedures for fast power system restoration and study what kind of processes are required for the planning of the restoration. The dissertation focused on a situation where neighbouring countries cannot support the restoration.
"For example, there could be a nationwide blackout in Finland and the neighbouring countries could not support the restoration," Antti-Juhani Nikkilä explains.
In such situation, the behaviour of the electricity network is very different from the normal daily operation. Since modern power systems are very reliable and major blackouts are rare, there is not much practical experience from the system restoration. In addition, new types of electricity production and other new technologies change the power system behaviour. Such changes pose a challenge for the mathematical modelling of the power system in case of rare disturbances and blackouts.
Simulations alone are not sufficient for restoration planning
The analyses of exceptional disturbances require computer simulations. In his dissertation, Antti-Juhani Nikkilä observed that the simulation models for normal system operation are not necessarily suitable for the analyses of major blackouts since the relevant behaviour of the system is so different. Simulations alone are not likely able to identify the critical issues that may be encountered during the restoration. Therefore, practical restoration field-tests are required.
"Restoration field-tests could provide measurement data which can be further used for the detailed modelling of different kinds of grid equipment. In addition, it is also possible to minimize the impact of the simulation model inaccuracies by selecting specific restoration procedures," Nikkilä says.
The results of the thesis may be used to enhance the restoration procedures in case of blackouts affecting entire power systems and consequently to enable fast and robust system restoration. In addition, the results may be used to improve the IT-systems used for the power system operation.
The study has been carried out at the Finnish transmission system operator Fingrid Oyj, where Nikkilä works as an expert.
The doctoral dissertation of MSc. Antti-Juhani Nikkilä in the field of electrical energy engineering titled Power system restoration after a system level blackout: Measures for system operation to manage technical uncertainties during the bottom-up restoration of a transmission network will be publicly examined at the Faculty of Information Technology and Communication at 12 o’clock on Friday 16 September, in Tietotalo auditorium TB109 at Tampere University Hervanta Campus (Korkeakoulunkatu 1, Tampere). The Opponents will be Professor Herwig Renner from TU Graz, Austria and Professor Matti Lehtonen from Aalto University, Finland. The Custos will be Professor Pertti Järventausta from the Faculty of Information Technology and Communication.
The dissertation is available at http://urn.fi/URN:ISBN:978-952-03-2507-7
Photo: Sanna-Kaisa Harjula