IEEE Power & Energy Magazine - November/December 2021 - 54

Current state-of-the-art services (e.g., capacity,
ancillary services, and so on) fall far short
of future service requirements.
to ensure cost-effective and reliable operations and investment
decisions. At the heart of organizing the power system
are defining " services " that need to evolve with the changing
characteristics of the power system. They are fundamental
to supporting the sociotechnical objective of reliably
maintaining supply-demand balance at all points in time, at
all locations, at least cost, equitably, and with minimum impact
on the environment.
These services determine the operation and planning of
the electricity grid across all time scales; the required characteristics
of the technologies connected to the power system;
and, through commercial mechanisms, the incentives
to innovate and invest and to do so equitably. Current stateof-the-art
services (e.g., capacity, ancillary services, and so
on) fall far short of future service requirements. There is a
danger of developing electricity grids that are costly, unreliable,
inequitable, and inflexible and will therefore not deliver
the step change needed for the energy transition.
For example, with increasing penetrations of variable renewables,
there is a decline in " inertial response " and a correspondtable
6. Services Research Program questions.
53) How should the definitions of services for IBR-dominated
grids be structured? Can standard services and standard
characteristics be defined that are reasonable for large and
small IBRs and across VRE, storage, and demand response
interfaces?
54) What methodologies can be employed to determine if
strong/stiff voltage-control services can be reliably provided
through reactive power droop or active regulation?
55) What models and methods are necessary to quantify the
ability of VRE to provide essential reliability services to the
grid, and how do system operators quantify the value of these
reliability services (for example, as an input to system-specific
market/incentive design questions)?
56) What roles can offshore wind and high-voltage dc clusters
play in providing energy system flexibility?
57) How can system performance requirements be translated
into reliable new technology solutions?
58) How can system operators quantify the transmission-level
service opportunities from DERs? What are the practical and
technical limitations to the reliable provision of various DER
services?
59) How can transmission-level services provided by DERs
be valued? What DER transmission-level service valuation
methodologies are best suited as a compromise between
simplicity and full cost-reflectiveness?
54
ieee power & energy magazine
ing deterioration in frequency control. There are also several
compounding factors. For instance, distributed solar PV systems
are reducing the efficacy of the existing emergency frequency
controls in place in many jurisdictions to arrest frequency decline
(e.g., underfrequency load shedding).
Inertia has not been in short supply historically as it
comes inherently with synchronous generation and therefore
was not deemed to be a service. There are several candidate
solutions to declining inertial response, starting with
focusing directly on supply-demand balance and ignoring
frequency control, which is only an indicator of this balance.
Maintaining frequency as the indicator of a supply-demand
imbalance and deploying fast-frequency-response and gridforming
converters as substitutes for physical synchronous
inertia constitute another approach. Interestingly, some of
the energy sources for these substitutes can be the VRE
sources themselves.
There are many other examples, including a possible
change in the most fundamental of all services: energy. With
increasing penetrations of variable renewables, there may
well be a point where the energy service, because of oversupply,
is replaced in the hierarchy by capacity. Because of the
way in which rules for participation have developed, many
services today may be biased toward provision by more established
technologies, in particular synchronous machines, as
other technologies (e.g., IBRs and storage) were not previously
in existence.
Developing system services in technology-agnostic ways
such that the full capabilities of all eligible technologies
are utilized, including those on the distribution grid and in
customer premises, can help system operators meet reliability
in a cost-optimal fashion. However, what is missing is a
unifying framework for defining and procuring services so
that the " best " combination of services is found, recognizing
that system characteristics, both technical and societal,
vary by location.
The Services Research Program questions (Table 6) aim
to quantify the technical requirements of a future power system
to maintain the supply-demand balance reliably and at
the least cost. A set of new services and/or a reordering of the
services hierarchy is needed to guide the transition toward
higher penetrations of variable renewables
in electricity
grids. This reordering should be based on their importance as
determined by fundamental electrical engineering, economics,
and social factors. The new services hierarchy may be
fundamentally different than those in the past. For instance,
under high penetrations of variable, zero-marginal-cost
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IEEE Power & Energy Magazine - November/December 2021

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