Techno-economic benefits of battery storage with grid-forming converters in low-carbon power grids

The decline in rotational inertia as a consequence of the increasing penetration of inverter-connected generation source may concern the grid security. This requires a significant amount of additional ancillary services. Grid-Forming (GFM) converters are pivotal since they may provide active inertia and damping power. The proposed work assesses the system-level techno-economic benefits of battery storage assets - equipped with GFM converters - delivering a variety of ancillary services under any operational mode. The resulting security-constrained scheduling model simultaneously optimizes energy production, rotational inertia, traditional primary response, inertial and damping response from GFM converters and secondary response. The formulation optimizes system-level requirements to ensure safe rate of changes of frequency, nadirs and quasi-steady state levels, avoiding unnecessary overscheduling of the battery power/energy headroom. Moreover, the model explicitly considers the effect of the energy recovery after delivering secondary response so that its deliverability from batteries is always guaranteed. Numerical simulations, applied to a future low-carbon scenario of the Great Britain system, prove the benefits of the proposed methodology against previous approaches.