IEEE Power & Energy Magazine - July/August 2021 - 31

operational constraints of the preferred resources, namely
availability, duration, and intermittency.
First, the load growth is forecasted using a bottom-up
approach that aggregates the expected load growth up from
the circuit level to the substations. Predictably, the anticipated
incremental load has fluctuated year to year since the launch
of the PRP due to variations in load growth projections, DER
adoption rates, and their impact on the load, temperature fluctuations,
and changes in customer behavior. The next step in
the portfolio design process is the development of load shapes
and resource attributes. The hourly load shape forecasts
developed for 2022 are used to quantify the demand above
the 2013 baseline. This incremental load need for 2022 is to
be served by the preferred resources portfolio and defines the
attributes required to meet the delta: quantity, duration, frequency,
time frame/season, and time of day.
The final step in the process is the selection of the bestfit
preferred resources for the PRP portfolio by matching the
acquired preferred resources by the hour based on the highest
peak day forecasted in 2022. The portfolio is reevaluated when
preferred resources are added or removed (e.g., due to contract
terminations) or when new forecasts are developed. The
portfolio design process is refined periodically to incorporate
updates based on the measured performance of the preferred
resources deployed.
The PRP DER portfolio currently deployed to fill the gap
between the 2013 baseline demand and the 2022 load shape is
detailed in Table 1. The size of the portfolio is 122 MW, with 78%
(95.44 MW) being the result of customer participation in tariffed
programs. Also, the PRP DER portfolio includes a 19.6-MW
combined heat and power (CHP) resource not under contract with
SCE but deployed in the PRP area to support its objectives.
Portfolio Performance
The performance of the PRP portfolio is evaluated every year
based on the availability to offset demand when required and
the contribution levels, particularly on peak days and across
peak hours, as illustrated in Figure 3. The 2019 portfolio performance
was assessed considering the peak demand day throughout
the year, which was recorded at about 1 p.m. on 26 July
2019 (shown as an inset in Figure 3). Table 2 details the type
of DER, deployed capacity, measured peak load reduction, and
effectiveness in reducing the demand above the 2013 baseline.
The DER effectiveness, defined as the ratio of the measured
grid load reduction to deployed DER capacity in the 2019 PRP,
ranges from 31% energy efficiency to 96% CHP. Overall, the
effectiveness factor for all of the aggregated resources is 71%,
demonstrating that DERs can offset peak demand. Nonetheless,
hurdles remain. For example, advanced and mature analytical
tools are lacking to assess the full potential of DERs.
Since customer participation in the tariffed programs
accounts for the majority of the PRP DER portfolio, a deeper
understanding of customers' behaviors and higher visibility
into behind-the-meter resources are critical next steps to
increase the effectiveness of the PRP portfolio. The PRP
july/august 2021
program has provided valuable data points for planning, integrating,
and operating the 30 GW of generation capacity and
10 GW of storage from DERs required for a carbon-free future
in California. Hence, SCE plans to continue measuring the performance
of the PRP DER portfolio to gain insights into when
and how to incorporate DERs to support grid reliability and
regulatory goals.
table 1. The PRP DER portfolio
for the southern region covering 13 cities.
Deployed DER Capacity (MW)
Resource Type
Energy efficiency
Permanent load shift
Demand response
Distributed
generation-behind
the meter
Distributed
generation-in front of
the meter
Energy storage-
behind the meter
Energy storage-in
front of the meter
Hybrid (distributed
generation with
energy storage)
Subtotals
Total
4.78
0.82
95.44
2
25.16
122
table 2. PRP DER portfolio performance
at peak load, 26 July 2019.
Resource
Type
Distributed
generation
(CHP)
Distributed
generation
(PV)
Demand
response
Energy
efficiency
Energy
storage
Total
Deployed
DER Capacity
(MW)
19.6
47.92
16.04
15.05
3.4
102.01
Measured Peak
Load Reduction
(MW)
18.9
35.54
10.59
4.66
2.67
72.36
Effectiveness
96%
74%
66%
31%
79%
71%
ieee power & energy magazine
31
1.4
1.4
Customer
Programs/
Tariffs
30.21
59.63
Competitive
Solicitations
7.62
3.84
11.7
Utility
Owned
IEEE Power & Energy Magazine - July/August 2021

Table of Contents for the Digital Edition of IEEE Power & Energy Magazine - July/August 2021
