Long term energy storage capacity optimization in energy buffer system

The intermittent nature of wind power, due to fluctuations in wind speed, makes wind energy to be unsteady. This results in frequency and voltage deviations in the grid when such sources are connected to the grid. This paper describes a design of battery energy storage system (BESS) in a buffer scheme to reduce the effects of intermittent wind power from wind farms. The problem is formulated as an optimization problem to maximize the economic benefits gained from selling of the dispatched power to the grid against the cost of BESS. The results of the optimization give the size of BESS, so that the BESS can provide the most probable smoothing of wind power. Two constraints are applied to this optimization problem, the voltage level across the dc-link of the buffer and the state of charge (SOC) for batteries must be kept within the upper and lower limits.