In English

Modelling an Electricity System with Load Following Nuclear Power Plants

Karl Gustavsson
Göteborg : Chalmers tekniska högskola, 2014. 35 s.
[Examensarbete på avancerad nivå]

A significant part of the greenhouse gases emitted today comes from the electricity generation around the world. Since the greenhouse gases contribute to the global warming it is of great interest of how the energy system can be changed to lower these emissions. Another reason for changing the energy system is that the fuels used may become much more expensive, or even become very scarce, when the availability of the fuels decrease. Renewable energy sources have no or low net emissions of greenhouse gases and does not, per definition of being renewable, use any fuel that may become depleted. Some of the renewable sources have variable production, like when the wind is blowing. This has the consequence that the other electricity sources may need to be more flexible to be able to meet the instantaneous electricity demand at each hour, here approximated with a hourly balance between supply and demand. Since a large part of Sweden's electricity is generated by nuclear power and since nuclear is also a power source with no or very low greenhouse gas emissions, it is of interest what role it takes in an electricity system with large amounts of variable renewable generation. A model that minimizes the total production cost from all power producers of southern Sweden was developed for this purpose. The power limits for load following nuclear power plants (NPPs) were investigated and were thereafter used as input to the model. Acquired data for wind and hydro power were also put into the model to model the electricity system of southern Sweden. When modelling load following NPPs, the pressurized water reactors (PWRs) could vary between 30 and 100 % of the rated power and the boiling water reactors (BWRs) could vary between 70 and 100 % of the rated power. The results from the simulations shows that the nuclear reactors can be up and running at a higher degree when using load following techniques. When the annual electricity production from wind power stays at 15 TWh or below, it is enough that only the pressurized water reactors use load following techniques to avoid shut down of any reactors when the power from the other sources is high. If the electricity production from wind goes above that, it is necessary to use more reactors as load following reactors if shutdowns of NPPs are to be avoided. At 20 TWh annual electricity from wind power it is necessary that all reactors use load following techniques to avoid shut downs in the model. When comparing the total electricity generated from nuclear at different wind power penetration levels, there is very small differences between when load following is used in the nuclear reactors or not. This is most likely because of the large amount of cheap hydro power in the system and and that export of electricity was forbidden in the model.

Nyckelord: nuclear power, energy systems modelling

Publikationen registrerades 2014-07-02. Den ändrades senast 2015-01-19

CPL ID: 200048

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