Abstract
The objective of the paper is to study the potential behaviour of a power system with high share of nuclear and less thermal plants, in which variable RES insertion increases − for example the French case −, in order to determine the specifications for the design of a potential nuclear reactor with high “manoeuvrability”. Moreover, the flexible reactor may participate more in the supply − demand balance and in particular during large frequency fluctuations caused by the high variability of RES. The studies are carried out with the PowerFactory software, which make it possible to highlight specific needs regarding the power ramp for an “ideal” flexible nuclear reactor. Using a benchmark network, the Kundur “2 areas-4 machines”, the flexibility requirements are obtained as a function of the grid disturbances. For this purpose, the penetration of variable RES is progressively increased, while nuclear power is reduced and thermal power plants are totally suppressed. The study shows that a drop in RES production directly impacts the minimal frequency. A faster response speed of nuclear power makes it possible to restore this stability and return to normal operating conditions imposed by the grid operator. This paper describes therefore the process of obtaining the flexibility criterion for different cases of insertion of variable RES.
Highlights
The balance between electricity production and consumption must be ensured, at all times, on an electric power system
The study encompasses the following sections: – Section 2 describes the main hypotheses that are suitable for carrying out the approach. – Section 3 describes the network and the different elements of the power grid. It requires the adaptation of existing model; a specific nuclear regulation and variable Renewable Energy Sources (RES) productions model in order to simulate an equivalent power system to the French grid. – Section 4 gives the different steps for gradually increasing variable RES production and decreasing thermal resources in order to define flexible specifications for nuclear electric power in different mix cases. – Section 5 deduces how flexible nuclear power plants can improve the stability of the system with a high proportion of variable RES, before the conclusion in the last section
Current policies are moving towards the massive penetration of variable renewable energy sources and the elimination of fossil fuel units due to their high CO2 emissions
Summary
The balance between electricity production and consumption must be ensured, at all times, on an electric power system. The compensation of the production/consumption fluctuation is currently ensured by using controllable generation units. These units are mainly based on traditional fossil fuel (coal, gas, etc.) and hydraulic (hydroelectric barrage or pumping/turbining). Nuclear power plants (NPP), which are low carbon emitters, contribute but in a lesser extent than conventional thermal or hydraulic power plants, to the balance and frequency control thanks to their “load-following” mode. Their internal operating constraints prevent each nuclear power plant from participating strongly in stability control due mainly to pellet-to-clad interaction [4]. The innovative idea of this study is based on improving nuclear manoeuvrability, looking for flexibility requirements that could be addressed by the nuclear power plant design in other studies
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