IEEE Power & Energy Magazine - November/December 2021 - 52

As the fossil resources that have traditionally
provided the backbone of restoration are displaced,
IBRs will need to fill this gap.
seamlessly. Planning for all of these changes is critical. As the
primary energy resources change from fossil/nuclear fuel to
more VRE resources, and as more of these resources become
inverter based and distributed, the planning paradigm must
account for their different characteristics. As other technologies
(e.g., batteries) become more pervasive, they also increase
the need to update power system planning. Electrification and
integration of the other parts of the energy system (e.g., transport
and heat) can dramatically alter demand patterns, which
will also impact the planning paradigm.
To keep up with the trends, the metrics and methodologies to
plan reliable and resilient power systems must be continuously
updated to ensure that they are " fit for purpose " and deliver the
required levels of reliability in the future. System operators all
have their unique variation on long-term planning, driven in
part by their regulatory, policy, and market environments.
Despite these variations, one area of clear consensus is a
need to focus on network infrastructure planning as many
system operators have relatively limited responsibility for
generation investments. Instead, they are tasked with planning
transmission investments to accommodate a range of
future generation portfolios while maintaining the robust and
reliable operation of the power system. Thus, the processes
and tools required to plan the future bulk power system in a
liberalized market setting, where the generation side of the
equation is market and/or policy driven, should focus on the
transmission system and ensure that there are enough services
to maintain reliability and resilience.
Driven in part by climate change, the events on power systems
are becoming more extreme and highlight some commonmode
failures; it is important to account for them in planning
activities. As the consumer becomes more active in the power
system, possibly creating a more heterogeneous demand side,
the whole concept of planning standards may need to be adapted
to enable a more optimal system. DERs in particular can influence
traditional reliability control services like underfrequency
load shedding, impacting operating practices in important ways
that must be accurately accounted for at the planning stage.
Finally, the more dynamic a power system is, the more
complex its operations become (see Table 4), and the more
important it is that the planning process accounts for the operational
details. This poses a computational burden that can be
addressed with advanced computational methods, using both
hardware and software, and/or methods for representing power
system operations accurately in a reduced form. In sum, defining
the network infrastructure of least regret is growing more
complex. Operators must establish the necessary tools and
52
ieee power & energy magazine
processes to plan and build (and eventually operate) a future
power system that is dominated by VRE, IBRs, and DERs
while accounting for risk and uncertainty holistically.
Developing new planning metrics, methods, and tools
to capture the characteristics and influence of a changing
resource mix, including new flexibilities from demand-side
resources and storage, is the focus of the Planning Research
Program (Table 5). This program does not consider distribution
network planning or include detailed considerations of
electrification, sector-coupling impacts, or DERs. Nevertheless,
these will need to be represented in planning exercises
or, in the case of sector coupling, by quantifying demand
response or long-duration storage assets.
Sometimes It Will All Go Wrong
In common with all systems, there are times when the lights
go out. These failures are unavoidable but can be minimized
in a cost-effective manner, which is the main driver of all 59
research questions.
When the power system does go black, it must be restored
quickly and efficiently. Traditionally, flexible hydropower or
fossil-fueled power plants, such as simple cycle gas turbines or
diesel generators, have provided the first step of a black start.
Inverter-based resources such as wind generators and solar
PVs cannot currently provide a black start, and their participation
in the subsequent steps of system restoration is generally
avoided. However, IBRs generally have the potential for
fast and customized behavior; they offer the potential to provide
valuable contributions to restoration efforts, such as fast
frequency-containment reserves and tailored inertia response.
As the fossil resources that have traditionally provided
the backbone of restoration are displaced, IBRs will need to
fill this gap. Additionally, high penetrations of DERs complicate
traditional " cold load pickup " practices as blocks of
load that have embedded distributed PVs or distributed storage
may result in complex behavior that must be considered
in the restoration process. The sheer number of distributed
generators requires new forms of awareness and automation
to make their inclusion feasible for operators.
There are several unique problems associated with " bootstrapping "
the system with solar and wind IBRs from a black
condition back to normal operation. This is addressed in question
52: " How do system operators black-start a system with
very few (or no) synchronous machines? " The first challenge
is to ensure that, in planning and operational time frames, the
IBRs have a sufficient energy source available to enable the
black start (i.e., sufficient wind speeds, solar irradiation, or
november/december 2021
IEEE Power & Energy Magazine - November/December 2021

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