  Battery energy storage is an essential component of a microgrid. The working
temperature of the battery is an important factor as a high-temperature
condition generally increases losses, reduces useful life, and can even lead to
fire hazards. Hence, it is indispensable to regulate the temperature profile of
the battery modules/packs properly in the battery energy storage during the
operation. In view of this, a two-layer optimal control and operation scheme is
proposed for a microgrid with energy storage. In the first layer, an optimal
control model is formed to derive the optimal control policy that minimizes the
control efforts, consisting of the fan speed and battery current magnitude, in
order to achieve a temperature distribution reference over the battery modules.
In the second layer, the system operator of the microgrid performs an optimal
power flow to search for the optimal temperature distribution reference used in
the first stage and the corresponding operating current of the battery that
minimize the operation cost of the entire microgrid system. This two-layer
scheme offers a great computational benefit that allows for large-scale
integration of batteries. A case study is performed on the proposed two-layer
model to illustrate its performance.
