Analytical Evaluation of Battery Energy Storage System Dispatch in PV Integrated Grid

Increasing penetration of Photovoltaic (PV) systems reduces the ability of the traditional grid to ensure adequate inertial and governor response under contingency. Battery Energy Storage System (BESS) can be an effective support system under such scenario as it can supply rapid active power to counter frequency change. However, instead of releasing the available capacity or allocating reserve obtained from offline solution, a power outage-dependent real-time BESS dispatch strategy may allow the grid operator to maintain stable frequency with less energy injection. In addition, this can lessen the overuse of the installed battery, leading to a longer lifespan and lower maintenance costs. This paper develops an analytical model for BESS dispatch in a utility-scale PV integrated grid, considering total outage, support from committed generators, and frequency-dependent loads. Dynamic simulations on the IEEE 39 bus test network show that the calculated BESS dispatch keeps the system frequency above the predefined threshold. Further sensitivity tests are conducted by varying the outage level between $5 \%$ and $15 \%$ of the total load and the load frequency relief (LFR) between $1 \%$ and $2 \%$. The obtained results indicate a maximum of $4.95 \%$ and $5.55 \%$ difference between the analytical outputs and the simulation findings for outage and LFR, respectively.