IEEE Power & Energy Magazine - November/December 2020 - 111

needs to be grid supportive and fix issues
created by the DER addition, such as intermittency, variability, and high voltage.
At the end of 2019, SDG&E had
approximately 179,000 PV installations with a nameplate capacity totaling 1,233 MW. In aggregate, this is the
largest generator in SDG&E's service
territory, which, due to NEM policies,
is not directly metered or controlled by
grid operators. As a result, grid operators face formidable challenges. They
must maintain balance between supply
and demand on the grid in real time
in the face of fluctuating energy generation from PV systems that can challenge grid stability.

Advancing DER
Integration at SDG&E
DER adoption has grown exponentially over the past two decades, and
it is poised to continue to expand. At
SDG&E, we take pride in having a
very streamlined interconnection process. Using an online customer portal,
commercial and residential fast-track
customers (86% of all applications)
can obtain permission to operate in

parallel with the grid within 1.3 and
2.5 days, respectively.
Our distribution resource plan incorporated pilots of PV aggregations
with smart inverters to attempt primary voltage regulation and microgrid
services. Significant investments were
made in hosting capacity analysis software that, in a year and a half, changed
the distribution planning process. Our
load flow analysis went from 1 peak
hour of the year to quasi-dynamic 576 h
for 10 different DER profiles, looking
at two days (typical high and low) for
24 h for each of the 12 months of the
year. Engineers at SDG&E also developed a distribution investment deferral
framework for distribution services as
defined in California: peak thermal
overloads, reliability back-tie, resiliency/microgrids, and voltage regulation.
SDG&E also quantifies the nature
of the need (e.g., magnitude) for DERs
to potentially defer more typical solutions, and there is a distribution planning advisory group and an independent professional engineer reviewing
utility projects annually. Wholesale
market participation by DERs and ag-

gregations for both energy and ancillary services are available.

We Have Our Work
Cut Out for Us
While our industry has made significant strides, there is still a long way to
go before we can collectively realize
the vision of leveraging DERs for grid
services. To help our industry get there,
an important next step is to take an
open and transparent inventory of the
gaps that need to be addressed to ensure
the world's energy system remains safe,
reliable, resilient, and secure. Progress
also needs to be made in the areas of interoperability requirements, validated
model-based development, standards
development, and end-to-end testing.
Additionally, the DOE, its national
labs, and other R&D organizations
around the globe should leverage their
funding to conduct research and pilot
studies to resolve these issues and identify, at a macro level, the cost to achieve
the end-state vision. The five articles in
this issue about the integration of DERs
are a start in this direction.
p&e

book review (continued from p. 108)
The authors note that the examples
and problems are a key part of the
treatment of the material and serve two
purposes: 1) to illustrate analytical expressions with numerical values and 2)
to provide examples of practical power
systems. In both cases, the examples
and problems show that seemingly
complex situations can be solved using some straightforward calculations.
Students in a graduate course using
this text will be expected to perform
dynamic simulations as part of their
learning experience.
There is a comprehensive companion website for this book hosted

by Wiley at www.wiley.com/go/chow/
power-system-modeling. The site is divided into a section for instructors and
for students. The instructor site contains
examples, lecture slides, problems, and
solutions. The student site comprises
the examples, including downloads of
the computer files needed for dynamic
simulations, which can be used directly
by the Power System Toolbox (PST), a
MATLAB-based software. Computer
code for additional models is also available at the companion website. PST is
open sourced and free for education use.
A user would need a MATLAB license
to use PST.

The authors note that Part I of the
book is suitable for an advanced undergraduate course for students who have
completed an introductory course on
power system analysis, while Part III
features advanced topics suitable for a
second graduate course on power system dynamics.
This book is a welcome addition to
the body of literature on power system
modeling, computation, and control
and will prove valuable both in an
academic setting and for practitioners.
-John Paserba
p&e

november/december 2020

ieee power & energy magazine

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IEEE Power & Energy Magazine - November/December 2020

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