IEEE Power & Energy Magazine - September/October 2019 - 33

IEEE Standard 1547-2018 has several functionality options and
does not specify communication or cybersecurity requirements,
which leaves significant issues to be resolved.

exchange and requirements for control and communication.
These aspects span concerns for interconnection requirements, planning, and real-time distribution operations.
Customer DERs is used here broadly to also include DER
aggregators and independent DER developers. Coordination
between DOs and customers is essential to ensure customer
DER operations do not adversely impact system operations
and safety and that DER services meet the required performance and communications service levels.
Several relevant standards have been developed to address
interconnection and interoperability issues, such as IEEE
Standard 1547-2018. However, additional effort is required
to enable the application of such standards; for example,
practical implementation will require certification testing
and market adoption as well as viable strategies for applying
the advanced functionality offered by these standards. For
example, IEEE Standard 1547-2018 has several functionality
options and does not specify communication or cybersecurity
requirements, which leaves significant issues to be resolved at
the state or utility level to ensure effective distribution systems
and customer coordination. A recent report from the Association of Edison Illuminating Companies (AEIC) summarizes
lessons learned from several demonstrations of DER services
in the United States. It presents the following set of issues that
require resolution regarding coordination between DOs and
customer DERs:
✔ Reliability of DER communications was well below
the average communication reliability of distribution
supervisory control and data acquisition systems.
✔ Reliable measurement and verification for DER services are needed.
✔ Timely coordination between the DO and aggregator
is essential.
✔ Harmonization of standards and related certification
testing is needed.

Coordination of Distribution
With Transmission
System operators are faced with the dual challenge of managing variable, bulk-level, renewable power generation and
a variable net load driven by customer DERs, which poses
the larger issue given the lack of visibility and controllability. A 2018 CIGRE Joint Working Group C2/C6.36 report
identifies critical issues for TSOs in managing frequency,
balancing, system voltage control, and bulk power system
(BPS) restoration with significant DER integration and
september/october 2019

utilization. This report discusses findings from an international survey of TSOs and identifies the following issues in
common with the AEIC report:
✔ observability
✔ effective controllability
✔ timely operational coordination.
In addition, the North American Electric Reliability Corporation (NERC) has continued to assess the issues involving a more distributed power system. The System Planning
Impacts from Distributed Energy Resources Working Group
(SPIDERWG) prepared a draft scope document that identifies "key points of interest related to system planning,
modeling, and reliability impacts to the BPS." The working
group's activity list includes the following actions related to
transmission-distribution coordination:
✔ Develop detailed guidelines related to the recommended information sharing and data collection for
necessary information to flow effectively across the
T-D interface to support BPS reliability needs.
✔ Develop recommended practices and guidance for assessing the performance of the BPS under increasing
penetrations of aggregate DERs.
✔ Provide guidance for distribution-level monitoring to
improve steady-state and dynamic modeling of aggregate DERs, including the use of smart meters, dynamic disturbance recorders, phasor measurement units,
and other recording devices.
✔ Provide technical recommendations for the adoption
and use of IEEE Standard 1547-2018.
✔ Provide guidelines, white papers, compliance guidance, and so on in support of NERC reliability standards addressing interconnection requirements.
The SPIDERWG activities are consistent with the findings of the CIGRE report, clearly indicating that there
is much work needed to address myriad issues related to
large-scale DER integration and utilization. Although these
reports do not address all of the TDC coordination issues,
they illustrate the importance of undertaking a thorough
assessment to determine the cyberphysical and structural
changes needed. These should be done as part of a holistic
assessment of the grid architecture.

International Efforts
Many regions and countries have begun to assess the structural
changes needed to integrate DERs at scale and utilize their
export energy and grid services capabilities. The following
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IEEE Power & Energy Magazine - September/October 2019

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