Grid Forming Inverters for Spinning Reserve in Hybrid Diesel Microgrids

In order to evaluate the ability of a Grid Bridge System(GBS), or energy storage-backed grid forming inverter, to provide spinning reserve in an islanded microgrid with significant variable generation, we have developed a high-fidelity system model. In a loss-of-wind scenario, the GBS system significantly improves both the frequency nadir as well as the transient overvoltage response of the system. This case was analyzed for a system with one, two, and three diesel generators both with and without the GBS. System stability for the one generator plus GBS case outperformed all generator system, even for the three-generator case. This indicates that spinning reserve can be shifted from the generators to the GBS without sacrificing system stability, allowing the diesel generators to operate at more economical conditions, saving significant fuel costs over the long-term implementation of the GBS.