IEEE Power & Energy Magazine - March/April 2022 - 43

if the same solar resource is large enough and paired with a
properly sized battery, it may provide the complete value of
a generic DER.
There is precedent for
the treatment of " energylimited
resources " in wholesale capacity markets, where
independent system operators define a capacity factor for
each resource type accounting for its " availability " to provide
energy. In the context of value to the distribution grid,
other utilities, for example, in New York, define a coincidence
factor that captures the alignment of resource availability
and grid need. The choice of coincidence factor
depends on the grid service required for the bulk, transmission,
and distribution systems as well as DER location
and type. To simplify the calculation, these utilities use a
single-value approximation for the coincidence factor. For
example, they model the normalized (per nameplate capacity)
energy behavior of the DER on a time series basis and
compare that normalized behavior to peaks in the system
load and constraints.
Since the generic LMV is already determined on an hourly
basis and reflects the temporal and spatial aspects of grid needs,
the DER-specific LMV is a relatively straightforward calculation
that involves multiplying the normalized hourly profile of
specific DERs by the generic hourly LMV profile. The calculation
of the DER-specific LMV is formulated as an optimization
problem. In this formulation, 1 kW of a specific DER
technology or bundle of technologies is optimally dispatched
against the hourly LMV adhering to operational limits on the
DER technology.
This approach does not require
any additional data other than DER
limitations since the generic hourly
LMV is already calculated. Further,
it is applicable to more complex situations,
such as energy storage charge
and discharge as well as the bundle
of technologies where rules of thumb
might fall short and/or become more
complicated to establish. Numerical
examples for several DER configurations
are shown in Figure 2. For this
analysis, renewable resources coupled
with battery energy storage are
limited to charging the battery with a
renewable output.
Figure 2 illustrates several
conclusions for the specific case
studied:
1) For this situation, the PV
system can produce 78%
of the value of the generic
DER (a DER that is dispatchable
and capable of
providing sufficient active
and reactive power).
march/april 2022
DER-Specific LMV
100
10
20
30
40
50
60
70
80
90
2) The PV system captures much more of the value than
its capacity factor would indicate. This is because, in
this example, thermal overloading correlates reasonably
with peak PV production.
3) Combinations of PVs and storage are more effective
than PVs only, depending on the ratio of storage to PVs
in terms of power and energy. Due to the grid location
and feeder constraints, a multihour storage capacity
may be required to realize a generic DER value.
4) For this case, the wind resource can produce around
55% of the value of a generic DER. In this example,
the feeder capacity need is better aligned with the
temporal profile of PVs than that of wind.
5) Similar to PVs combined with battery energy storage
configurations, adding storage to wind installation
would increase its contribution and, thus, value.
Mapping LMVs and making these maps accessible would
provide customers and developers insight into the potential
incentive for each DER technology deployed at each location.
This incentive is based on calculating the marginal
value of each DER technology to the grid as a portion of the
avoided distribution upgrade costs.
Practical Capabilities That Are Needed
to Implement the VDER Framework
There are practical aspects to implementing the VDER computation
methodology. First, the engineering and planning
processes need be adjusted to support quantifying DER
figure 2.The results of evaluating PVs with different storage configurations against a
particular LMV profile. BESS: battery energy storage system.
ieee power & energy magazine
43
Percentage of Generic LMV
Generic
PVs
Wind
PVs + Wind
BESS (2 h)
BESS (6 h)
PVs + BESS (0.25kW, 2 h)
PVs + BESS (0.25 kW, 6 h)
PVs + BESS (0.5 kW, 2 h)
PVs + BESS (0.5 kW, 6 h)
Wind + BESS (0.25 kW, 2 h)
Wind + BESS (0.25 kW, 6 h)
Wind + BESS (0.5 kW, 2 h)
Wind + BESS (0.5 kW, 6 h)
PVs + Wind + BESS (0.25 kW, 2 h)
PVs + Wind + BESS (0.25 kW, 6 h)
PVs + Wind + BESS (0.5 kW, 2 h)
PVs + Wind + BESS (0.5 kW, 6 h)
IEEE Power & Energy Magazine - March/April 2022

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