IEEE Power & Energy Magazine - September/October 2019 - 52

and tools presented in this article apply generally to information and communication technology integration, although
we focus here on operational situations, especially between
organizations that must establish agreements.
In the parable of the charging car, the integration scenario
involves the energy service provider, the customer's chosen platform, and the EV. This is represented in Figure 3, with interactions among the client, service providers, distributors, and
distribution operations. The growing integration and coordination of devices at the customer edge of the system means that
millions of interface situations involving EVs, distributed generation, batteries, and flexible loads are at stake. This new world
is at our doorstep, and making integration simple and reliable
will be a necessary endeavor as our society moves forward.
The degree to which today's distributed energy resources
(DERs) are integrated with system operations, such as electric
cars, solar panels, and controllable loads, is far from the plugand-play necessity. Consider the interoperability categories in
Figure 2. At the lower technical levels, the aspects of integrating customer-owned devices and systems are addressed by a
wide variety of mature standards and support all forms of wired
and wireless communication. At the communication protocol
level, everything from customers' equipment to their facility
management integration uses a wide variety of standards, some
open and some proprietary. Each technology ecosystem (such
as solar photovoltaics (PVs), EVs, and load management) has
its own, often competing, set of protocols for communicating
with customer apparatus. Electric utility-oriented projects tend
to use technical-level communications standards derived from
electric power field equipment automation standards, while
customer component suppliers frequently use standards developed in their professional domains (for instance, automotive
engineering, industrial systems, and building automation).
Table 1 is based on a U.S. Department of Energy (DOE) grid
modernization project that investigated the gaps between DER
interoperability standards. The diversity of standards organizations and the types of professional organizations that support
them are highlighted across the different types of technologies
being integrated. At the interoperability level, the emerging information modeling standards have differences from each DER
technology ecosystem (for instance, PV systems, EV charging,
battery storage systems, and building-demand response). The
format differs across environments, as do information sciencebased methods and tools, such as the Unified Modeling Language standard, and the knowledge representation for defining
models. Some information models are extensions of existing
standards that use specialized language formats, making harmonization of specifications across different ecosystems difficult. Existing information models tend to support direct-control
types of interactions with DER equipment for reading statuses
and setting actions. In this situation, the models must represent
all the relevant details of the remotely controlled apparatus so
that the algorithms can map the equipment. For example, a system remotely governing a smart inverter on a rooftop solar setup
must model all the appropriate characteristics of that equipment,
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meaning much information must be exchanged and kept current
for the controller to properly do its job.
At the interoperability organizational level, architectural
ideas supporting greater separation of decision-making
functions that have clear lines of responsibility are emerging in the form of service-oriented requests that describe
the desired outcomes independently from how the results
are produced. This can promote a business process that significantly simplifies information models based on service
definitions and expected performance rather than detailed
equipment models that must be exchanged and continually
maintained. Standards that uphold service-oriented interactions are starting to be adopted in specific ecosystems.
While there is some progress at the organizational level,
there are few grid services available for DER coordination.
Most interactions with DER facilities are directly controlled
by utilities or third-party aggregators. Service contracts may
or may not stipulate the purpose of control, so the grid service
or system objective is not always apparent to the DER facility.
Some programs are designed to encourage consumer behavior changes in ways that help system operations without using
direct-control methods. Examples include tariff schemes, such
as demand capacity charges that provide an incentive to stay
below a power limit, and time-of-use programs that change the
price of energy depending on when it is consumed. Systems
in which retail prices are dynamic beyond fixed schedules are
rare, but interest in variable rate scheduling is growing.
The following are observations about the interoperability characteristics for aggregators of DERs:
✔ Most programs are used primarily for peak capacity
management and spinning reserve grid services, but
each jurisdiction defines the services differently. The
lack of standardization across market systems requires
aggregators to customize their technology.
✔ Aggregators tend to use proprietary communication
and control platforms to directly govern DERs. They
work with a customer's facility management system
to regulate the local equipment, or they command the
DER equipment directly through their own technology.
This makes interfaces with DER facilities aggregator
dependent and hinders switching between providers.
✔ From an architectural framework perspective, there
is little coordination between third-party aggregators
dealing with wholesale markets, and distribution system operators. Problems in system operation loom as
these programs scale to high penetration levels within
a distribution feeder.
Cybersecurity issues exist across the organizational, informational, and technical levels as well. Most DER facilities operate without any cybersecurity requirements, although
the adoption of standards is improving. Even in California,
where the California Independent System Operator (ISO) has
set cybersecurity requirements for DER providers, the specifications stop at the aggregator level as DER facilities internally operate without cybersecurity requirements. Existing
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IEEE Power & Energy Magazine - September/October 2019

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