Role of Energy Storage Systems for Ancillary Services

The large-scale integration of wind power into modern electricity systems presents fundamental operational challenges, owing to the stochastic and non-dispatchable nature of wind resources. This paper examines the colocated of Battery Energy Storage Systems (BESS) with utility - scale wind power plants as a technically and economically viable strategy for mitigating generation variability and enabling firm power delivery. A 60 MW wind power plant, comprising Permanent Magnet Synchronous Generators (PMSG),interfaced with the grid via back-to-back Voltage Source Converters (VSC) is modeled in the PSCAD/EMTDC electromagnetic transient simulation environment, alongside a Lithium Iron Phosphate (LiFePO₄) - based BESS connected at the 110 kV point of common coupling. Three representative operational scenarios are evaluated over a 24-hour simulation horizon: (i) standalone wind plant operation without storage; (ii) wind-BESS co-operation with real-time power smoothing and constant 40 MW grid delivery; and (iii) combined operation under active power curtailment with simultaneous reactive power regulation. Simulation results demonstrate that BESS effectively eliminates generation volatility, enables energy time-shifting from periods of surplus to peak demand intervals, and delivers critical ancillary services: including primary frequency response and dynamic reactive power compensation with a discharge response time of approximately 100 milliseconds. The study fidnings have shown that BESS integration transforms an inherently intermittent wind generation into a dispatchable generation resource, enhances power system stability, improves the capacity factor of the wind plant, and has potential to generates additional economic value through the elimination of imbalance penalties, reduction of curtailmens, and access to ancillary service revenue streams.