MicroGrid Renewable Integration Dispatch and Sizing (MiGRIDS) Analysis of Spinning and Regulating Reserve Options for Wind in an Alaskan Diesel Microgrid

St. Mary’s is a remote, isolated, Alaska microgrid that relies on diesel generation. Recently, a wind turbine generator (WTG) with a rated capacity just below system peak load was installed to help reduce diesel fuel consumption. With this WTG, St. Mary’s could significantly reduce their fuel consumption and run significant amounts of the year without any diesel generators (DG) online (“diesels-off”). However, wind power needs to be covered with spinning reserve capacity (SRC) and regulating reserves. Since there are no other sources, this needs to come from the DG, which does not allow them to turn offline and reduces the amount of potential fuel savings. The Alaska Village Electric Cooperative (AVEC) has invested in a “Grid Bridging System” (GBS), an energy storage system meant primarily to provide SRC and regulating reserves to allow the DG to go offline, scheduled to be installed in 2023. This paper uses the open source Python-based software tool Micro Grid Renewable Integration Dispatch and Sizing (MiGRIDS) to investigate the benefits and impacts of several methods to reduce or replace SRC and regulating requirements on the DG. These include optimizing SRC requirements, adding a GBS to the system, using short-term wind forecasting and using a fast acting controllable thermal energy storage system (TESS). The GBS resulted in the greatest fuel savings. Optimizing SRC and short-term wind forecasting resulted in a small decrease in fuel consumption on their own, but in combination with a GBS resulted in a much greater reduction. Finally, the TESS was able to regulate a poorly controllable WTG so that it behaved similar to a highly controllable WTG, at some expense to wind import.