Investigating Small Modular Reactor's Design Limits for Its Flexible Operation With Photovoltaic Generation in Microcommunities

Use of flexible and dispatchable generation from the small modular reactors (SMRs) in combination with the nondispatchable generation from renewable energy systems (RES) can be an effective alternative to pursue the mandate of replacing the fossil-fuel based electricity with the carbon-neutral energy systems in the remote microcommunities. This paper evaluates the feasibility of SMRs' flexible operations in microcommunities with the photovoltaic (PV) generation as a case study. Considering the design limits of SMRs for (a) the range of net change in electrical power output and (b) the ramp rates of net change in turbine power, a power system study is conducted to cover the three aspects of flexible operations, namely: (1) Planned load-following, (2) Unplanned load-following, and (3) Frequency regulation. A generic governor model in power system simulator for engineering (PSS/E), a power system transmission and planning software, is adapted to incorporate the operating limits of the reactor for the dynamic simulation. The multitimescale approach, combining (a) steady-state time-series power flow analysis and (b) dynamic simulations with high-resolution solar irradiation datasets, is proposed to assess the implications of SMR's design limits. The results obtained on an existing remote feeder with three sets of operating limits—namely, the conventional, advanced and extreme limits of ramp rates juxtapose the SMRs' performance, given the challenging operating conditions with PV generation in remote locations. The results indicate that the SMR under study can accommodate the highest permissible PV penetration obtained by the hosting capacity analysis of the feeder under the clear sky conditions. However, dynamic simulations with the extreme PV variabilities show that the PV penetration level should be further limited so that the maximum deviations in SMR power levels stay within 40% of its rated capacity. SMR provides adequate frequency support for the PV penetration of up to 50% of the feeder maximum demand in this study.