Loss of Load Expectation
(LOLE) Methodology
ENGCTF Item-8
April 11th 2013
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Overview
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LOLE Definition & Background
Technical Details & Modeling
GADS Summary
Reference Links
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Loss of Load Expectation (LOLE) Definition…
LOLE is the measure of how long, on average, the available
generation capacity is likely to fall short of the load demand
Loss of Load Probability
(LOLP) is the probability
in a given hour
Sum of the Daily Peak
LOLP values is an
expectation (LOLE)
Sum of all LOLP values
is called Loss of Load
Hours (LOLH)
LOLE is used to study Generation(Resource) Adequacy
A product of Unit Availability
The “Perfect Storm”
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1-day in 10-years LOLE Criteria…
• LOLE is expressed as hours per year with the usual target
criteria being (0.1 days/year) or 1-day in 10-years
• MISO Resource Adequacy criteria for Planning Reserve
target is the industry standard LOLE objective
of less than1-day in 10-years
• NERC Standard BAL-502-RFC-02
Calculate a planning reserve margin that will result in the sum of
the probabilities for loss of Load for the integrated peak hour for all
days of each planning year analyzed being equal to 0.1. (This is
comparable to a “one day in 10 year” criterion).
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LOLE Process comparison:
PRM & Assessment Studies
LOLE
PRM Study
Assessments
Planning Reserve Margin (PRM) Study
1-day in 10-years LOLE
(0.1 d/yr)
LOLE
Software
Planning Reserve
Margin Requirement
(MW)
Seasonal, Long Term Reliability & Probabilistic Assessment Studies
Capacity Inputs (MW)
• Retirements
• Fuel Limitations
• Other Sensitivities
LOLE
Software
LOLE (d/yr)
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LOLE Software Tool…
• Multi-Area Reliability Simulation (MARS)
Program
– General Electric (GE) Company product
– Uses a sequential Monte Carlo simulation
• Steps through time chronologically and randomly
drawing unit availability
• Replicating simulation with different sets of random
events until statistical convergence is obtained
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LOLE Models Utilize an
Equivilized Transportation Model…
Detailed Transmission Model
• Typical Load/Power Flow model used in
transmission studies
• Retains transmission system details with a
system of voltage specific buses and voltage
specific branches
• Loads are modeled at bus level
Equivilized Transportation LOLE
Model
• Retains individual generating unit details
• System of interconnected zones/areas
• Aggregated load at a zonal level model
representation
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Major PRM variables include…
Unit
Availability
Load
Forecast
Uncertainty
(LFU)
• Unplanned Events
• forced outages, forced de-rates...
• Planned Events
• maintenance outages, seasonal de-rates, retirements…
• Generator Availability Data System (GADS)
• tracks and collects unit historic performance data
• Predicting exactly what the future load will be is not possible,
a LFU variable is needed to account for this uncertainty
• MISO’s Resource Adequacy construct is 1-year forward
looking the amount of LFU is a 1-year uncertainty value
• the uncertainty increases as the period of time between
forecast and actual increases
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LOLE Modeling Unit Availability…
• In the MARS LOLE model there are 3 unit types used to
model availability differently
– Typical Thermal Unit (most common modeling type)
• Uses Forced Outage Rates to randomly draw when units are
un-available (forced off)
• Example: Coal, Nuclear, CT, CC…
– Energy Limited Unit
• Used to model units with known monthly energy limits
• Example: Demand Response (limited use) type programs
Hydro & other storage type units, if fuel dependency is more of factor on
unit availability than forced outages
– Demand Side Unit
• Used to model units with a known hourly output profile
Typical Week(168 hrs) or Full Year(8760 hrs)
• Example: Wind Units and Demand Side programs if data is available
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LOLE Modeling Unit Availability continued…
• In the MARS LOLE model there are 2 different ways to
account for Planned Maintenance
– Manual Scheduled Maintenance
• Used when actual Start and End dates of planned maintenance is known
• Example: Nuclear refueling schedules
– Auto Scheduled Maintenance
• Used when only the typical duration of season maintenance practices
are known and not the actual dates
• Automatically scheduled to minimize loss of load (LOLE)
{biggest units scheduled first during the lowest load periods}
• A Planned Maintenance Rate can be derived from GADS data
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GADS Summary
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Generator Availability Data System (GADS)
– Event, Performance, Design1 and Fuel1 data records
– Historic data and performance information used to calculate unit specific
statistics
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Equivalent Forced Outage Rate demand (EFORd)
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Forced Outages are the random events that occur when a unit fails to run
Equivalent: accounts for Forced De-Rate events
demand: adjustment factor for units with low service hours
LOLE Model uses EFORd statistic calculated over the last 5-years
Outside Management Control (OMC) Events
– Force Majeure type of events: flood, hurricanes, transmission outages…
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eXcluded Equivalent Forced Outage Rate demand (XEFORd)
– XEFORd = EFORd with OMC events removed (excluded)
– RA Construct uses XEFORd statistic calculated over the last 3-years to
calculate Unforced Capacity (UCap) ratings of units
1NERC
only data records; MISO doesn’t collect this information
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Reference Links
• Loss of Load Expectation (LOLE) Study Reports
–
https://www.misoenergy.org/Planning/ResourceAdequacy/Pages/ResourceAdequacy.aspx
• Resource Adequacy Documents
– BPM https://www.misoenergy.org/Library/BusinessPracticesManuals
• BPM 011 - Resource Adequacy
– MISO Tariff: Module E-1
• https://www.midwestiso.org/_layouts/MISO/ECM/Download.aspx?ID=138166
• NERC Links
– NERC Standard BAL-502-RFC-02
• http://www.nerc.com/files/BAL-502-RFC-02.pdf
– GADS
• http://www.nerc.com/page.php?cid=4|43
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Contact Info
• Brandon Heath – (651) 632 - 8473
[email protected]
• Davey Lopez – (317) 249 - 5109
[email protected]
• MISO Stakeholder Working Group – LOLEWG
https://www.misoenergy.org/STAKEHOLDERCENTER/COMMITTE
ESWORKGROUPSTASKFORCES/LOLEWG/Pages/home.aspx
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