IEEE Power & Energy Magazine - July/August 2019 - 77

"Managing the New Grid." This panel explored power
system planning and operations challenges and opportunities as a result of changes to the power generation
resource mix, taking into consideration the steps initiated
by the North American Electric Reliability Corporation
(NERC), regional entities, industry, and FERC. The IEEE
Industry Technical Support Task Force provided a written
testimony and had an IEEE representative participating
on the panel. Although the testimony had a focused scope
and reach, the authors have expanded it through this article to discuss in-depth issues and potential solutions to
ensure reliable, secure, and safe operation of the electric
power system.

Generation Portfolio Trends and
Essential Reliability Services

subsidies for coal, nuclear, and renewable generation. The market would be streamlined by including consumers, prosumers,
and aggregators in the short-term markets for energy and ancillary services.
Extreme care must be taken so that the adoption of new
generation technologies does not undermine the reliability
and resilience of the electric grid. To address some of these
issues, FERC commissioners asked the following questions
at their reliability conference.
✔ Are essential reliability services (ERSs) adequately
quantified to augment existing measures of reliability
such as reserve margin?
✔ Is there an opportunity to further refine ERSs so that
they can be used to develop and deploy solutions to the
specific challenges facing the grid?
✔ Is there a need to better quantify ERSs so that they can
be provided through a market mechanism rather than
a reliability standard?
It is critical to ensure that new generation technologies [particularly inverter-based resources (IBRs), such as wind, solar,
and distributed energy resources (DERs)] have the capability
to provide ERSs to the electric power system. Quantifying the
value of ERSs in a technologically neutral manner (not only
for conventional generation but for IBRs) would be beneficial
for improving reliability and resilience. For example, IBRs
can provide reserve margins if the ERS is properly addressed
and recognized by system operators and in the marketplace.
Market mechanisms would require proper reliability standards
to price the ERSs provided by all technologies. Furthermore,
IEEE Standard 1547-2018 (IEEE Standard for Interconnection
and Interoperability of DERs with Associated Electric Power
Systems Interfaces) defines the ERS (i.e., frequency response,
ramping, and voltage support) capabilities for DERs interconnected to the distribution grid.

US$/MWh

GWh

The electric power industry is experiencing a rapid transition
from conventional generation to renewable and cleaner technologies. The U.S. trends are shown in Figure 1. This evolution is driven by regulatory and policy mandates as well as by
maturing alternative technology and associated cost reductions.
For instance, in the United States, the Eastern Interconnection
has experienced a significant adoption of cleaner generation
technologies (natural gas and, increasingly, renewables) and
the retirement of many coal and nuclear plants. The Electric
Reliability Council of Texas (ERCOT) and California markets
have experienced a substantial interconnection of renewable
generation. Wind generation is dominant in the ERCOT market and largely localized in the Texas Panhandle area, while
solar generation has modified the load-curve profile of the
California Independent System Operator (CAISO) and created
steep-ramping needs for operators during sunset and potential overproduction risks during daytime. Figure 2 shows the
effect of high solar penetration on the demand for fast-ramping
resources in early morning and late
afternoon and the overgeneration
potential that would require curtail30
Distributed Solar
ment of renewable resources.
25
Utility-Scale Solar
By 2030, the European Union
20
Imports
(EU) targets at least 40% reduc15
Other Renewables
Thermal
tion in greenhouse gas emissions
10
Nuclear
compared with 1990 and expects
5
Hydroelectric
0
to meet over 27% of energy con0 2 4 6 8 10 12 14 16 18 20 22 24
sumption by renewables. A large
Hour of the Day
contribution toward this goal is
(a)
expected to come from renew60
Real-Time
40
able generation, electrified heatAverage
20
ing and cooling (including heat
Hourly Price
0
pumps), and transportation.
-20
0 2 4 6 8 10 12 14 16 18 20 22 24
While continuing to pursue GHG
Hour of the Day
emissions goals, the EU has also
(b)
proposed restructuring its power
system. Objectives include ensuring figure 2. Examples of (a) the California ISO duck curve and (b) negative wholesmooth interconnections; mandating sale prices on 11 March 2017. (Source: U.S. Energy Information Administration.)
regional planning; and eliminating See also Hobbs et al.
july/august 2019

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