The use of large amounts of existing baseload NPPs capacities with a significant increase in renewable generation in the mathematical model of optimal dispatching of generating capacities of Ukraine’s power system leads to a significant surplus of electricity during peak power generation at solar PV’s, which necessitates additional sources of flexibility of the power system, such as battery electricity storage systems. The projects of new advanced nuclear power units provide for their use in flexible load modes with a maximum unloading of up to 50% of the rated capacity. Advanced NPP power units with small modular reactors are designed for even greater more maneuverable operation with possible unloading of up to 20% of rated capacity. The article presents approaches to modeling the use of NPP power units in variable load modes in the mathematical model of the optimal daily load schedule dispatching of Integrated Power System of Ukraine. The first approach is to model the operation of NPP power units similar to modeling the participation of cycling TPP units in covering the daily electrical load profile of the power system, in particular, changes in generation power in the range from minimum to nominal load levels, load rate. The second approach is to determination for each nuclear power unit of variants of modes of their hourly loading, the choice of one of which is made as a result of optimization. The modeling results showed that the choice of optimal flexible loading modes of new nuclear power units allows to provide the load balance of the power system almost completely with available capacities, including cycling TPP units, and the use of pump-storage generating units to transfer excess PV generation at peak hours of electricity consumption, which avoids the use of battery storage systems. Keywords: mathematical model of dispatching, operational mode, nuclear power unit, daily electric load profile, power system
Numerical study on CMT boron replenishment strategy for an AP1000 nuclear power unit
