Optimal Planning of Standalone Net-Zero Energy Systems With Small Modular Reactors

Renewable-based standalone systems are widely developed worldwide with the decentralization of power and energy systems. However, challenges are posed due to the intermittent nature of renewable resources and the lack of inertia. Small modular reactors (SMRs), a clean but also flexible and controllable energy, can be deployed to provide flexibility and inertia support to standalone energy systems with high penetration of renewable energy. In this paper, we propose a novel standalone net-zero energy system planning scheme that coordinates SMRs with other distributed energy resources, where both steady-state operation constraints and dynamic frequency security constraints are considered to guarantee the operational feasibility of the plan. Since the dynamics of SMR are very complex, the planning model becomes a complex and unanalytical optimization problem. To this end, we first develop a physics-informed data-driven approach to model the dynamic frequency characteristics of SMRs with high accuracy. On this basis, we propose a "checking and adjusting" heuristic approach to iteratively solve a series of MILP problems without the non-linear and unanalytical frequency constraint and then check whether the constraint can be satisfied. In this way, we can get a feasible and suboptimal solution in a tractable manner. Comprehensive case studies have been conducted, and results show that the inclusion of SMRs can substantially increase the flexibility and frequency security of standalone net-zero energy systems.