Peak Load Contribution (PLC) Overview
As a local distribution company (LDC) member of PJM
Interconnection, BGE is
responsible for determining the capacity and network transmission peak
load contributions (PLCs) for each electric account within the BGE
zone, aggregating these PLCs separately by capacity and network
transmission to the appropriate LSE, and reporting the total aggregate
PLCs by capacity and network transmission for each LSE to PJM.
Capacity Peak Load
As required by the PJM Reliability Assurance Agreement (RAA),
the PJM Office of the Interconnection (PJM OI) calculates the PJM
zonal capacity obligation. Each LDC in PJM's control area is assigned
a capacity obligation for its zone. The LDC is required to calculate
and report to PJM daily the capacity peak load contribution data,
aggregated by electricity supplier, for its zone.
In accordance with the PJM RAA and PJM rules and
procedures, BGE will calculate a system capacity peak load
contribution "ticket" for each electric account on an annual basis.
After the end of a summer period, PJM will identify the five highest
weather normalized PJM system coincident load hours that occurred on
different days over the period from June 1 through September 30. The
LDC-specific zones will identify the actual zonal loads associated
with these five hours. Each LDC-specific zone will reconcile these
five different hours back to the one hour weather normalized, system
coincident zonal peak load obligation. The consequent peak load
contributions will be calculated as an average over these five hours.
Each account's PLC will be updated on a yearly basis in accordance
with PJM rules and procedures.
Transmission Service Peak Load Contribution
Each local distribution company within PJM has a network
transmission service peak load contribution requirement. To allocate
fairly the LDC's daily requirement to electricity suppliers, network transmission
service peak load contributions (transmission PLCs) are determined. In
accordance with the Open Access Transmission Tariff (OATT) and PJM
rules and procedures, BGE will calculate a transmission PLC "ticket"
for each electric account on an annual basis. For a given year, an
account's daily network transmission service PLC requirement is based
on its load at the time of the actual unrestricted peak hours that
occurred during the twelve months ending October 31 of the prior
calendar year. (See PLC Peak Hours & Defaults) At the end of
this 12-month period, PJM and BGE will identify the five highest
unrestricted load hours that occurred on different days during this
12-month period. The LDC will reconcile these five different hours
back to the highest unrestricted peak load hour that PJM has
determined to be BGE's zonal peak load obligation. The consequent peak
load contributions will be calculated as an average over these five
hours. The account's transmission PLC will be updated in accordance
with PJM rules and procedures.
Daily Reporting of Peak Load Contributions
On a daily basis, BGE calculates and reports to PJM the sum
of the PLCs for each account served by the electricity supplier, known as the
"Supplier PLC." BGE computes the electricity supplier PLCs after the close of each
business day and submits them to PJM using PJM's eCapacity system and
published submission guidelines. The following sections describe the
methods and calculations used to derive electric accounts' and electricity suppliers' capacity and network transmission PLCs.
Calculating Annual Peak Load Contributions
Peak load contributions are typically processed differently
for the three metering types: (1) interval metered accounts, (2)
monthly demand metered accounts, and (3) monthly metered accounts
(without demand metering). Accounts with monthly demand meters or
monthly non-demand meters are also referred to as non-interval metered
Monthly kW demand
that have meter usage data including the account's highest demand
level (monthly kW peak) for the billing cycle and the on-peak
time-of-use (TOU) period. In addition to metered demands, kWh energy
usage is metered for each time-of-use period defined in BGE's retail
The derivation of the peak load contributions consists of
unreconciled peak loads.
profiled segment weight and obligation factor for each profiled
account's annual capacity and transmission peak load contribution.
A description of each procedure follows. The procedures are
further illustrated below by a simplified hypothetical distribution
system serving eight accounts: three monthly kWh metered accounts,
three monthly kW demand metered accounts, and two interval metered
accounts. An example for each type of account is given showing
calculations for one of the five hours averaged in deriving the
capacity and transmission PLCs.
Step 1: Determine Unreconciled Peak Loads
For each profiled segment and interval metered account, an
initial peak load estimate is obtained based on data metered at the
customer's premise. Premise level loads are adjusted for the
electrical losses that occur in BGE's transmission and distribution
system. Loss factors vary by voltage class and may be found under BGE Loss Factors. The loss-adjusted load
estimates are termed unreconciled peak loads since in total they may not exactly equal the
system load for that hour, and are therefore reconciled or scaled to
the known system load. For each peak hour used to calculate PLCs the
unreconciled peak is obtained as follows:
Interval metered accounts: the load for each interval metered electric account is
extracted and measured for any load curtailment impacts due to BGE's
active load management programs under Riders 5 and 6 (See Riders 5 & 6
in the BGE Retail Electric Service Tariff and the Active Load Management Programs link) .
Each load is then adjusted for
Non interval metered accounts: the average peak load for each profiled segment is obtained
from BGE's statistical sample of each profiled segment. (See Load Profiles) This aggregate peak load is allocated to each account
in the segment by applying an account-specific "usage factor". The
usage factor represents the ratio of the metered usage for the account
to the average usage of the profiled segment over the same period. The
total unreconciled peak load for the segment is the product of the
peak load for the segment, the loss factor for the segment, and the
sum of the usage factors for the segment.
Step 2: Reconcile Peak Loads
Unreconciled peak loads are then scaled to BGE's total
zonal load for each of the five hours included in the capacity and the
transmission PLC calculation. (See PLC Peak Hours & Defaults) An imbalance is computed as the difference between the total unreconciled load and BGE's total zonal load for each zonal peak hour.
This hourly imbalance is then apportioned to each interval metered
account and each profiled segment in proportion to its unreconciled
Step 3: Calculate the Profiled Segment Weight and
Obligation Factor for each Profiled Segment
Profiled segment weight for monthly metered customers: The sum of the
usage factors for each monthly metered profiled segment is the
profiled segment weight for that segment.
Step 4: Derive the Peak Load Contributions for each Account
Examples of Peak Load Contribution Calculations
There are four Excel® files illustrating the procedures for
calculating PLCs for monthly metered, monthly demand metered and
interval metered accounts, and for deriving reconciled load. For
reference purposes, an Excel® spreadsheet named "Customer PLC Datasheet Summary" lists the kW values by customer account used in the
calculation examples. The spreadsheets may be opened from this
location or downloaded as a zipped file called PLC Reconciliation Worksheets (zip).
The individual files are listed below:
Customer PLC Datasheet Summary
Interval Metered Accounts
Monthly Demand Metered Segment
Monthly Metered Segment (non-demand metered)