IEEE Power & Energy Magazine - July/August 2021 - 65

A high penetration of renewable energy brings significant
power system flexibility challenges, and the requirements for
flexible resources become increasingly critical.
The flexibility resources to form cloud-based energy storage
come not only from generators' and consumers' distributed
storage facilities but from an uninterruptible power supply
facilitated by data centers, communication base stations, and
even virtual storage from other energy sectors. The customer
of cloud-based energy storage (that is, the stakeholder who uses
it) can be a power system operator, generator, or load. Cloudbased
energy storage can serve power systems as a provider of
technical ancillary services. It can also furnish customers with
storage functionalities such as renewable energy forecast error
compensation and peak shaving for large industrial/commercial
consumers. Cloud-based storage can aggregate the spare
capacity of distributed resources to serve the demand of assorted
services across different timescales, e.g., from frequency
regulation, on a timescale of seconds, to peak regulation, on
an hourly timescale. Finally, cloud-based energy storage
benefits from the synergies of different flexible storage-like
resources, while distributed resources gain through more
effective utilization to recover their investment costs.
Technology Framework
Although each cloud-based energy storage project may have
different structures, the technology
frameworks have similarities.
A general technology framework
is illustrated in Figure 2. Its operation
is governed by a cloud-edge
coordinated control system. If it
provides services to a power grid,
it should be connected to the power
system dispatching center through
dedicated cyberoptical communication
networks. Otherwise, it
can be operated from a separate
dispatching center. The power system
operator dispatches cloudbased
energy storage in the same
way as a grid-scale storage facility.
The dispatching platform receives
energy storage charge and discharge
requests from power system
operators and customers and optimizes
distributed storage resources
to meet demand. Customers can
communicate with the dispatching
platform via wired and 4G/5G
wireless systems.
Cloud Energy
Storage
Customer
BMS
...
july/august 2021
The " edge " part of cloud-based energy storage is the
terminal box that monitors and controls distributed storage
resources. One terminal box can connect several distributed
storage facilities. The edge is in charge of communicating
with the dispatching platform and controls the distributed
storage resources. It may have some computing ability
that can strategically manage and aggregate the distributed
resources it collects. Communication between the dispatching
platform and its control terminal is usually through
4G/5G wireless networks, instead of dedicated fiberoptics,
so that the cost of building the system can be reduced.
Business Model
Various business models have been proposed and implemented
for aggregating distributed storage resources into
cloud-based energy storage. Major stakeholders include cloud
operators, storage owners, and storage customers, along with
power system operators and small customers, such as renewable
energy producers and industrial/commercial electricity
consumers. A distributed storage facility is usually invested
in by generation companies, energy consumers (e.g., factories),
even third parties. The owner of a storage facility leases
Power System
Dispatching Center
Private Communication
Network (Fiberoptic)
Public
Communication
Network
(4G/5G)
Cloud Energy
Storage Dispatching
Platform
Public Communication
Network (4G/5G)
Control Terminal
Control Wire
...
4G/5G
Control Terminal
Cloud Energy
Storage
Customer
...
figure 2. The cloud energy storage structure. BMS: battery management system.
ieee power & energy magazine
65
Battery 1
Battery 2
Battery N
Flexible
Resource 1
Flexible
Resource 2
Flexible
Resource 3
Flexible
Resource 4
Flexible
Resource M
IEEE Power & Energy Magazine - July/August 2021

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