In recent years, the Hungarian electricity system has been going through a rapid transition, the built-in solar PV capacity has more than doubled since 2022, due to the favourable support schemes. In parallel to the growth in weather-dependent electricity generation, the share of flexibly dispatchable - typically fossil fuel based - producers has been rapidly decreasing due to the efforts towards reaching carbon-neutrality targets, and this transition was further accelerated by high and volatile gas prices caused by the Russian-Ukrainian war.
Due to these changes in the electricity generation mix, the role of nuclear power plants, which were traditionally baseload providers, is gradually shifting towards active participation in the grid power balancing. In the last few years, the number of load reductions in nuclear units commanded by the TSO has also rapidly increased: from 55 of such events and 15.6 GWh in 2023 it has grown to 110 and 34.2 GWh in 2024.
Load changes can be best characterized by their ramp rates, amplitudes, and durations, which all could be a possible subject of optimization. After introducing a few principles and operating modes, possible solutions to improving different aspects of flexibility of both older and newer generation units are listed, including one the most promising developments of Framatome, OAPS (real-time predictive system for flexible operation). The system is presented in more detail, and a brief overview is given on the ongoing developments and expected outcomes.
One of the main questions when deciding on improving the maneuvering capabilities of nuclear power plants is the level of flexibility required from the grid side. For the analysis of this question, we have carried out hourly dispatch numerical simulations for the future electricity system of Hungary predicted for 2035. We have varied several flexibility constraints – maximum ramp rate, minimal stable load and minimum shutdown time – of the existing four Gen2 500 MW NPP units and of the two Gen3+ 1200 MW NPP units to be built, and compared these scenarios, drawing conclusions on the impacts of these changes on the simulation results, such as the occurrences of different types of load change events and yearly curtailments, while the properties of other producers remain unchanged.
We have analysed for the idealized deregulated electricity market conditions, how the flexibility of nuclear power plants impacts the system, how the hourly power generation mix changes, how much this affects the price of electricity and renewable curtailments.
Besides comparing the nuclear power plants’ estimated revenues from the electricity market, different aspects affecting the economics of the nuclear power plants are also discussed.
Through the presented results, conclusions and considerations altogether, the audience can gain insight into the formulation and unfolding of a complex research and development project conducted in cooperation between academia and industry.
