Disclaimer
• This training presentation is provided as a reference for preparing for the PJM Certification Exam.
• Note that the following information may not reflect current PJM rules and operating procedures.
• For current training material, please visit: http://pjm.com/training/training-material.aspx
PJM©2014
PJM ©2011 www.pjm.com 1
Interconnection Training Program
Load Scheduling
Incremental Loading Tables
LS2
Clement Lovasik
State & Member Training
Winter, 2011
PJM©2011 www.pjm.com 2
LS 2 Objectives
• Describe how incremental loading tables are derived
and used for “least cost” dispatch of generating units
to match load demand.
– Describe the two modes of submitting bids for
generating resources cost based and price based
– Describe how a cost based incremental loading curve
for a generating unit is developed, given the unit’s
incremental heat rate and fuel cost
– Develop and use an incremental loading table for a
sample system given unit data
– Describe the “least cost” method for dispatching
generating units for a sample system given an
incremental loading table for the system
Cost Based Bids
• Generation offers to the PJM market are capped at the
unit’s production cost plus a 10% adder
• Start up and no load costs can be updated daily
• Offer developed using guidelines of the Cost Development
Task Force (CDTF)
• CDTF Rules laid out in PJM Manual 15
• Cost based bids are used to cost cap the unit should the
units used to control for a contingency fail the “Three Pivotal
Supplier Test”
• All generators must have a cost based bid on file in eMKT
PJM©2011 www.pjm.com 4
Historic LMP-Capped / Negotiated Offers
Historic LMP-Capped Offers
• Generation offers using historic LMPs at the generation
bus where energy is injected
• Value is determined by calculating the average LMP at the
generation bus during all hours over the past six months in
which the resource was dispatched above minimum.
Negotiated Offers
• Offer is based on a negotiated value with the PJM Market
Monitor
• Case-by-case basis
PJM©2011 www.pjm.com 5
Price Based Offers
• Offer is based on what the generation owner believes the
market will bear
• Start-up and no-load costs can be updated every 6 months
• Prior to March 31 for period April 1 to September 30
• Prior to September 30 for period October 1 to March 31
• Units may file with MMU for cost-based start-up and no-loads
which may be updated daily
• When switching to Priced Based offers a unit may not
switch back to another type of offer
PJM©2011 www.pjm.com 6 www.pjm.com
Parameter-Limited Schedules
What are Parameter-Limited Schedules?
Parameter-Limited Schedules are limitations that could
be imposed on the parameters that generators submit as
part of their offer.
• All cost based offers are PLS
• Price based schedules can be PLS or non-PLS
These pre-determined limits are used when
certain operational circumstances exist.
www.pjm.com
Parameter Limited Schedules
• For each unit class, minimum acceptable operating
parameters include:
– Turn Down Ratio (Ratio of Eco Max MW to Eco Min MW)
– Minimum Down Time
– Minimum Run Time
– Maximum Daily Starts
– Maximum Weekly Starts
Future parameters MAY include: Hot Start Notification Time, Warm Start Notification Time, Cold Start Notification Time
Some parameters will be set based
on operating history of the unit
compared to % of PJM-defined unit
class
The initial Minimum Down Time for each unit is based on
the minimum of the Minimum Down Times submitted over
the prior 24 months, if the resultant minimum down time is
less than or equal to 110 percent of the PJM-defined unit
class Minimum Down Time. If Minimum Down Time
submitted for a unit is more than 110 percent of the PJM-
defined unit class Minimum Down Time, then the unit’s
Minimum Down Time will be set equal to 110 percent of
the PJM defined unit class Minimum Down Time.
i.e.
PJM©2011 www.pjm.com 8
Heat Rate
• Measure of efficiency of a unit in converting heat energy to electrical energy.
• Ratio of heat supplied by fuel (MBTU) to MWhr of electrical energy delivered by a unit. – MBTU stands for one million BTUs, which can also be
expressed as one decatherm.
– BTU stands for British Thermal Units
• As heat rate increases, efficiency decreases.
PJM©2011 www.pjm.com 9
Heat Rate
Heat Rate = MBTU = Heat Input (MBTU)
MWhr MW Output (MWhr)
Heat Rate = 312 MBTU/hr = 10.4 MBTU
30 MW MWhr
EXAMPLE:
PJM©2011 www.pjm.com 10
Heat Rate
• Optimum efficiency is normally at about 80% of full
load.
• Efficiency is less at lower loads due to heat required
to keep boiler hot an turbine spinning.
• At higher loads, losses in the turbine reduce
efficiency.
PJM©2011 www.pjm.com 11
Incremental Heat Rate
• IHR = Incremental Heat Rate
• IHR is significant to economic power system
operation.
• IHR is the change in heat input to a unit needed to
produce a given change in generation.
• IHR of a unit increases steadily with generation.
PJM©2011 www.pjm.com 13
Incremental Heat Rate
IHR = Increment of heat input (MBTU)
Increment of Power Output (MWhr)
PJM©2011 www.pjm.com 14
Incremental Heat Rate
• Increment of heat input =
392 MBTU/hr - 312MBTU/hr = 80 MBTU/hr
• Increment of power output =
40 MW - 30 MW = 10 MW
IHR = Increment of heat input (MBTU)
Increment of Power Output (MWhr)
IHR = 80 MBTU/hr = 8.0 MBTU
10 MW MWhr
PJM©2011 www.pjm.com 15
Incremental Cost
• Incremental cost for a unit at a given level of generation
is the cost per MW to produce the next increment of
power output.
• Is calculated by taking the product of the incremental
heat rate and the fuel cost.
INCREMENTAL COST (LAMBDA)
POWER OUTPUT IHR INC. COST
(MW) (MBTU/MWhr) ($/MWhr)
20
30 7.6 (7.6*2.3) = 17.5
40 8.0 (8.0*2.3) = 18.4
50 8.4 (8.4*2.3) = 19.3
60 8.8 (8.8*2.3) = 20.2
70 9.2 (9.2*2.3) = 21.2
80 10.2 (10.2*2.3) = 23.5
90 11.6 (11.6*2.3) = 26.7
100 12.7 (12.7*2.3) = 29.2
Inc. Cost = IHR * Fuel Cost
$/MWhr = MBTU/MWhr * $/MBTU
Fuel Cost = $2.30 / MBTUKEY
PJM©2011 www.pjm.com 18
Incremental Cost
Incremental Cost = MBTU x Fuel Cost
MWhr
Incremental Cost = 8.0 MBTU x 2.3 = 18.4 $/MWhr
MWhr
MBTU P
POWER MBTU
Relationship between Incremental Cost and Incremental Heat Rate
Cost for an Increment of Power P = Increase in MBTU needed to produce P Incremental Cost = IHR X Fuel Cost
($)
MWhr (MBTU) MWhr
X ($)
MBTU
Fuel Generating Unit Electrical Energy
$ X MBTU
MBTU MWhr
$ MWhr
=
PJM©2011 www.pjm.com 21
For Economic operation of a power system all generating units should be dispatched
at equal incremental cost.
Rate 1 Unit 1 Unit 2 Unit 3 Total 14.0 100 100 100 300 15.0 200 200 200 600 16.0 250 250 250 750 17.0 300 300 300 900
18.0 350 350 350 1050
PRINCIPLE OF ECONOMIC DISPATCH
Principle of Economic Dispatch
PJM©2011 www.pjm.com 22
Load (MW x 1000)
1 3 5 7 9 11 13 15 17 19 21 23
50
46
42
38
34
30
22
26
$5
$10
$15
$20
$25
$30
$35
$40
$45
Hour of Day
Dispatching Generation to Meet Load
PJM©2011 www.pjm.com 23
Exercise GT-2.1
PJM©2011 www.pjm.com 24
Questions
???