Abstract
Battery Energy Storage System (BESS) can provide frequency support to the power system by adjusting active power flow, but this may negatively impact local voltage. To mitigate this, the BESS can simultaneously inject or absorb reactive power to regulate voltage levels. This work analyzes the reactive power compensation necessary for a BESS to participate in frequency markets while upholding local voltage levels during reserve activation. Using a LinDistFlow framework, a case study on the IEEE 33-bus system is performed for one month of operation for a grid-connected BESS that maximizes profit while upholding the voltage levels in the grid, and reserves reactive power to counteract worst-case voltage impacts. To have sufficient reactive power to counteract voltage impact during activation, the BESS reduces frequency market bids by 34.8%. This consideration impacts the profitability of the BESS, capturing the need to address these service costs with the distribution system operator (DSO).