  Leveraging electrochemical and thermal energy storage systems has been
proposed as a strategy to reduce peak power in data centers. Thermal energy
storage systems, such as chilled water tanks, have gained increasing attention
in data centers for load shifting due to their relatively small capital and
operational costs compared to electrochemical energy storage. However, there
are few studies investigating the possibility of utilizing thermal energy
storage system with resources to provide ancillary services (e.g., frequency
regulation) to the grid. This paper proposes a synergistic control strategy for
the data center with a chilled water storage providing frequency regulation
service by adjusting the chiller capacity, storage charging rate, and IT server
CPU frequency. Then, a three-stage multi-market scheduling framework based on a
model predictive control scheme is developed to minimize operational costs of
data centers participating in both energy and regulation markets. The framework
solves a power baseline scheduling problem, a regulation reserve problem, and a
real-time power signal tracking problem sequentially. Simulation results show
that utilizing the thermal energy storage can increase the regulation capacity
bid, reduce energy costs and demand charges, and also harvest frequency
regulation revenues. The proposed multi-market scheduling framework in a span
of two days can reduce the operational costs up to 8.8% ($1,606.4) compared to
the baseline with 0.2% (\$38.7) energy cost reduction, 6.5% (\$1,179.4) from
demand reduction, and 2.1% (\$338.3) from regulation revenues.
