POWER April 2021 - 15

FOCUS ON O&M
liable and repeatable approach for connecting
their distribution power plants
to the utility grid.
Figure 4 shows an example of a utility
circuit with a D-VAR VVO and a new
distribution solar plant. The utility-owned
D-VAR VVO ensures that existing customers
served by this circuit do not experience
power quality problems due to
the new solar plant, while also protecting
the utility's mechanical tap changers
from mis-operation and excessive wear
and tear.
3. A D-VAR VVO distribution-class STATCOM
installed in a 15-kV class feeder. Courtesy:
AMSC
reliably managing voltage by owning and
operating the voltage regulating assets
on their distribution circuits. As increased
variable
distributed
generation
causes
greater load dynamics in the distribution
grid, utilities must invest in a more dynamic
voltage regulation system.
Distribution solar plants incorporate
devices called inverters between the solar
panels and the utility grid to extract
DC power from the panels and convert
it to the AC power required by the distribution
grid. Inverters are owned by
the plant operator and physically located
within the power plant, where they are
connected to the low-voltage AC bus
that is also owned by the plant operator.
Incorporating utility-owned D-VAR
VVO STATCOMs as the primary dynamic
voltage regulation solution and implementing
commonsense configuration
guidelines for utility-owned inverters
can provide plant developers with a reFinancing
Options for
Utility-Owned STATCOMs
For any generation project, a utilityowned
voltage regulation approach that
incorporates the D-VAR VVO distributionclass
STATCOM will allow the utility to
concentrate on what they do best-voltage
control and management-while simultaneously
enabling the developer to
focus on what they do best-rapid and
reliable plant development. Utility-owned
dynamic voltage regulation will permit
both the utility and the plant developer
to maximize system operational reliability
for the service lifetime of a plant.
With an average installed capital cost in
the range of 2% to 3% of the cost of the
generating plant, the D-VAR VVO distribution-class
STATCOM offers utilities a
broadly feasible low-cost upgrade.
Two financing models can be employed
to accommodate different environments.
In the first model, the developer pays, and
the utility owns and operates. This model
is similar to traditional upgrades offered by
utilities, such as protection upgrades or a
dedicated feeder upgrade. Cost recovery
details are defined in an interconnect agreement
signed by the developer and the utility.
Successful approaches can range from
the developer paying up front for the upgrades,
to a monthly fee structure for the
plant, or some combination of both.
In the second model, the utility pays
for the upgrade, with utility rate-base
recovery. This model is no different from
the way utilities recover costs for other
voltage-regulating assets necessary to
ensure system reliability. When connecting
a new generating plant to an existing
distribution feeder, the D-VAR VVO
can be employed as a primary voltage
regulator on the circuit. This model can
be most appropriate for utilities experiencing
broader adoption of distributed
generation on several utility circuits,
as well as utilities that are pursuing renewable
targets and need to accelerate
and streamline interconnections of
renewable generation.
Meeting Today's Challenging
Distribution Needs
Demand for connecting generating
plants to the distribution grid will only
continue to grow. Distribution-connected
generation offers utilities and developers
a unique option where system
issues such as congestion and complex
transmission system interconnection requirements
can be avoided. In the U.S.
alone, there are thousands of MW-class
distribution power plants currently in the
planning phase. Many of these projects
will require cost-effective solutions to
address voltage issues if they are to be
funded and constructed.
STATCOM technology has been applied
successfully in the transmission grid
for more than 30 years, establishing itself
as a trusted tool for ensuring system reliability.
Derived from STATCOM's proven
performance and engineered for today's
distribution systems, the D-VAR VVO provides
utilities with a powerful, cost-effective,
and easily implemented solution for
meeting today's changing and challenging
distribution requirements.
-This article was contributed by AMSC,
a system provider of megawatt-scale
power resiliency solutions.
Valve Actuator Diagnostics
for Predictive Maintenance
A predictive approach to finding potential
issues with steam or gas turbine valve
actuators can help power plant operators
realize cost savings and avoid unit downtime.
Having a way to analyze actuator
diagnostics can include conducting a
hysteresis test to gather data.
Utilizing the data to establish a predic4.
An existing distribution feeder with a D-VAR VVO allowing connection of a new distribution
solar plant. The D-VAR VVO protects the utility and its existing customers from experiencing
power quality issues. Courtesy: AMSC
April 2021 | POWER
www.powermag.com
tive maintenance practice allows operators
to optimize a unit's availability, while
also reducing maintenance costs. The
15

http://www.powermag.com

POWER April 2021

Table of Contents for the Digital Edition of POWER April 2021