> FOCUS A MODEL SYSTEM
The sheer size and complexity of the electric-power grid
makes it challenging, if not impossible, to continuously monitor
and track possibly millions of data points per minute. Therefore, power-system modeling is vital for condensing the volume
of data down to a manageable number of analytics that focus on
important issues that require operator attention.
Practically speaking, utilities use power-system modeling
for planning and design calculations.
“Utilities use models for analyses, such as planning for
growth in load and to make decisions concerning capital equipment and future upgrades,” Cale said.
Protection engineering is another practical component of
“For example, utility engineers can examine the timing and
sequences of breakers, relays and switches to plan for and better isolate faults and reduce outage times,” he said.
Models, and the analytical data generated by them, are also
important in both capacity planning and creating integrated
“Capacity planning is how utilities, independent system
operators and regional transmission organizations try to discern how much new generation capacity is required to meet
reserve margins,” Bodell said.
Integrated resource plans are multiyear projections on
which infrastructure investments will be required in the
power system to meet changing conditions. These plans help
utilities incorporate resources such as demand response and
The challenges associated with power-system modeling
primarily involve obtaining the appropriate and correct data
required to accurately and adequately represent the network
“With solar photovoltaic [PV], battery storage and other
emerging technologies, some of the challenges lie in developing
models that appropriately integrate them with the power-system grid model,” Sahni said.
Why should an EC care?
According to Sahni, power-system modeling is important to
electrical contractors (ECs) because they can use the data to
perform specific power studies and evaluate the impact of the
building under construction on the power-system network.
“Alternatively, the contractor can hire third-party expertise
to perform those power studies to better understand the technical and economic impacts the facility will have on the power
system or vice versa,” he said.
Some contractors working on new facilities may be called
on to supply information that must be included in a utility’s
power-system model. The biggest issue for the contractor, then,
would be to supply information pertaining to the steady-state
and dynamic characteristics of a facility’s solar PV, wind power
or energy-storage resources. These resource technologies will
certainly include the newer “smart” inverters, and that information will be vital to utilities as part of their control strategy
for intermittent renewables.
According to Cale, ECs that are familiar with power-system
modeling can work with utilities to perform design calculations
for both the bulk-transmission system as well as the distribution
system to determine design specifications, such as transformer
ratings, conductor sizes and relay timing.
“One caveat is that contractors that perform power-system
(modeling) should ensure that they have a detailed enough
model, or use a software package that does, to accurately represent the system’s underlying physics,” he said.
Another reason to be familiar with power-system modeling,
Bodell said, is the increasing need for contractors to understand
electricity market prices and how demand-response operations
can interact with those wholesale markets.
“Electrical contractors who understand these models will
be able to respond to evolving market demands and be more
involved in choosing and implementing the controls and other
smart-building systems that take better advantage of the interaction between retail and wholesale electricity markets,” he said.
As the country moves toward a next-generation electric
grid that integrates more renewable and other distributed generation technologies, there will be an increased emphasis on
power-system modeling and its ability to evaluate the impact
of such technologies on the grid and on ensuring that they are
integrated reliably. Adoption of renewable-energy technologies
are also starting to blur the lines between the transmission and
distribution sides of the industry, leading to the development
of combined transmission- and distribution-system models.
“With the growing deployment of renewable-energy generators on the distribution system, it will eventually be impossible
for utilities or contractors to examine the transmission system
without considering generation occurring on the distribution
system,” Cale said.
BREMER, a freelance writer based in Solomons, Md., contributes
frequently to ELECTRICAL CONTRACTOR. She can be reached at
410.610.7164 and firstname.lastname@example.org. I S T
Utilities use models for analyses
such as planning for growth
in load and to make decisions
concerning capital equipment
and future upgrades.