Designing off-grid renewable energy systems for reliable and resilient operation under stochastic power supply outages

Abstract

The power supply from solar and wind generators is not only inherently variable but also prone to failure due to rare-weather related events, i.e., hailstorms, icing. Current system sizing strategies often consider system reliability or resilience but rarely consider them simultaneously. Here, we proposed a sizing approach for an off-grid power system to supply a minimum power threshold (Lth) during power disruption events. The Lth concept ensures blackout avoidance and enough dispatchable stored energy during power outages. We developed several scenarios with 4- to 24-hour simulated outage events occurring multiple times per year. After sizing a system, designs are tested by simulating the systems’ operation based on data containing stochastic outage events. The resulting lost load is recorded to assess system reliability and resilience. Results showed that, regardless of outage frequency, total annual stochastic outage durations up to 32 h did not affect the optimal capacities of system components while ensuring the same reliability level. However, system capacities increased by up to 90% when the annual outage duration increased to 144 h. Meanwhile, introducing a minimum power threshold, Lth = 0.97, further increased the renewables generation and storage capacity up to 50% and 7%, respectively. Systems’ resilience tests showed an 80% chance of a system designed with the Lth approach to withstand the prolonged stochastic power disruptions, while this value is only 25% for the systems designed using the conventional approach.