The Groton Florence Roche Elementary School (FRES) backup power project is a battery energy storage system (BESS) microgrid that will supply power to the school in the event normal grid power is not available.

The BESS manufacturer required an electromagnetic transient modeling (dynamic modeling) report prior to acceptance of a purchase order. One goal for the report was to identify the inverter design parameters sufficient to power the school loads.

Based on a detailed review of the facility loads various scenarios were identified to evaluate BESS performance. PSCAD cases were created for each scenario and the simulation results were summarized for the client and manufacturer to review.

In addition to the dynamic modeling, steady state short circuit and load flows evaluations were performed to estimate unknown equipment characteristics and improve model assumptions.

SCOPE OF SERVICES

• Identify the BESS inverter design parameters requested by the BESS manufacturer.
• Generate an electro-magnetic transient modeling (dynamic modeling) report for the supplier to review prior to acceptance of the purchase order.
• Determined the BESS inverter current contribution to support transformer energization, and motor inrush using PSCAD scenarios.
• Reviewed scenario results for unacceptable voltage sag and swell conditions and recommend mitigations as necessary.
• Determined the AC short circuit current in both grid following and grid forming modes. These values aid with equipment selection and protection design considerations.
• Evaluate black start operation of the BESS inverter system.