Per Unit Displacement of Synchronous Inertia With BESS Synthetic Inertia Devices

Synthetic inertia offers the potential to increase power system stability during generation-load imbalances; particularly when conventional generation has been displaced by non-synchronous in-feed. This study is based on three frequency transients caused by the loss of 14% of the synchronous generation on the Irish system. Analysis of PMU data from power plants is used to determine the per unit displacement potential with battery energy storage systems of differing delay times and ramp rates. It is observed that synchronous generators undergo a step change in power output during frequency transients. The unsuitability of a droop response for a synthetic inertia response is demonstrated and that a step change in power output is required to maximize inertial participation. The displacement results are compared to existing and proposed operating characteristics of the Irish system.