Stability and fuel savings Trade-Offs in a Renewable-Diesel-Battery isolated power system under N-1 contingency

• Evaluate frequency stability in an isolated power system under N-1 contingency conditions. • Analyze the impact of different operational strategies on system resilience and fuel consumption. • Show the impact of integrating a spinning reserve battery on stability and diesel generator operation. • Provide insights into balancing fuel efficiency and reliability in hybrid diesel-renewable power systems. This paper presents a dynamic model of a diesel generator incorporating detailed governor dynamics and an empirical representation of turbo lag. The model is applied to an isolated hybrid power system comprising diesel, renewables (hydroelectricity and solar PV), and battery storage, based on the real-world configuration of the Tahitian grid. The study utilizes two distinct modeling approaches: a short-term simulation at the millisecond scale for evaluating frequency stability under transient conditions, and a longer-term (10-minute scale) unit commitment model for assessing operational dispatch strategies. The system’s capability to handle N-1 contingencies, specifically the loss of the largest diesel generator, is investigated under multiple scenarios. Results indicate that simplified generator models and reserve assessments can significantly underestimate frequency instability risks. Furthermore, incorporating battery storage as a controllable reserve substantially reduces frequency deviations and enhances diesel generator efficiency. These findings underscore the importance of multi-timescale modeling that realistically captures generator dynamics and operational constraints when evaluating the stability and operational efficiency of isolated power systems.