Post on 21-Apr-2020
transcript
Reliability Measures and Risk Assessment
Andrew Slone, Engineer, Reliability Performance Analysis, NERC
EPRI Workshop, February 23, 2012
2 RELIABILITY | ACCOUNTABILITY
Overview
• Reliability Measures 2011 Risk Assessment of Reliability Performance Report
2012 State of Reliability Report
Overview of ALR Metrics and Trends
Severity Risk Index
• Future Integrated Reliability Indicators
3 RELIABILITY | ACCOUNTABILITY
Reliability MeasuresR
elia
bili
ty Im
pro
ve
me
nt
Organizational Effectiveness
?
?
??
?
?
??
?
?
? System/Event-Driven Metrics
Reliability Condition-
Driven Indicators
Standards/ Statute-Driven Metrics
Organization Effectiveness
Metrics
4 RELIABILITY | ACCOUNTABILITY
2011 Annual Report
• Annual Report “2011 Risk Assessment of Reliability Performance” Culminates a 3 year process to provide a view of risks to reliability
Approved by the NERC Board of Trustees on August 4, 2011
Available at: http://www.nerc.com/docs/pc/rmwg/2011RMWG_Annual_Report.pdf
State of Reliability Report
Standards Driven
Events Driven
Condition Driven
Integrated Measures and Analysis
5 RELIABILITY | ACCOUNTABILITY
Integration and Analysis
Critical Infrastructure
Protection
Standards Dev &
PrioritizationCompliance
Events Analysis
Events Driven
Standards Driven
Condition Driven
TADS
GADS
DADS
EVENTS
Metrics
Data Source Integration and Analysis
6 RELIABILITY | ACCOUNTABILITY
2012 State of Reliability Report
• New in 2012 State of Reliability Report Tighter integration of sources to ascertain historic
Bulk Power System reliability
Focus on providing relevance for both industry and regulators
Additional Data Sources
8 RELIABILITY | ACCOUNTABILITY
Metrics - Improving Trends
ALR Title
1-3 Planning Reserve Margin
1-4 BPS Transmission Related Events Resulting in Loss of Load
2-5 Disturbance Control Events Greater Than Most Severe Single Contingency
6-2 Energy Emergency Alert 3
6-3 Energy Emergency Alert 2
6-11 Automatic AC Transmission Outages Initiated by Failed Protection System
Equipment
6-12 Automatic AC Transmission Outages Initiated by Human Error
9 RELIABILITY | ACCOUNTABILITY
Metrics – Inconclusive Trends
ALR Title
2-3 Activation of Under Frequency Load Shedding
2-4 Average Percent Non-Recovery of Disturbance Control Standard (DCS)
Events
4-1 Automatic AC Transmission Outages Caused by Protection System
Equipment-Related Misoperations
6-12 Automatic AC Transmission Outages Initiated by Human Error
6-14 Automatic AC Transmission Outages Initiated by Failed AC Circuit Equipment
10 RELIABILITY | ACCOUNTABILITY
Metrics – New/No Data
ALR Title
3-5 IROL/SOL Exceedance
6-1 Transmission Constraint Mitigation
6-15 Element Availability Percentage
6-16 Element Unavailability Percentage
1-5 System Voltage Performance
1-12 Interconnection Frequency Response
12 RELIABILITY | ACCOUNTABILITY
Severity Risk Index (SRI)
• Focus on significant events and quantify the historic system performance using daily outage data GADS and TADS daily outages, forced only
MW load loss and restoration duration from disturbance event reports
Could be considered similar to a daily, quarterly or yearly SAIDI metric for distribution systems
If everything was out of service, all load was unserved, the day’s score would be 1000
If no lines or units were out of service and no load was lost the day’s score would be 0
Normal “good days” will measure higher than 0
14 RELIABILITY | ACCOUNTABILITY
Integrated Reliability Indicators (IRI)
• Develop the conceptual model of reliability risks
• Establish quantitative measures for evaluating the performance of the indicators
• Support risk-informed decision making
• May be able to correlate over the long term to predictive measures of reliability risks and if so…
• Estimate the effectiveness of reliability risk reduction and/or mitigation
15 RELIABILITY | ACCOUNTABILITY
EDI Calculation
• The EDI is derived from Severity Risk Index (SRI)
• SRI = wT ∙(NT) + wG ∙(NG) + wL ∙(LLS)
• Where: SRI = severity risk index for a specified event,
wL = weighting of load loss,
LLS = normalized MW of Load Loss in percent,
wT = weighting of transmission lines lost,
NT = normalized number of transmission lines lost in percent,
wG = weighting of generators lost,
NG = normalized number of generators lost in percent
ysDurationDa
SRIysDurationDaEDI
16 RELIABILITY | ACCOUNTABILITY
SRI Calculation
• Load Loss and duration (for 80% of load restored)
Restoration Promptness Level (RPL)
oRPL = 1, if restoration < 4 hrs
oRPL = 2, if 4 <= restoration < 12 hrs
oRPL = 3, if restoration >=12 hours
Load Loss Severity (LLS) = (RPL/3)*(Load Loss MW/Daily Peak Load)
LGen
Gen
T
TSRI LS
baseloss
LOSSMW
baseloss
LossWeighted6.01.03.0
_
_
_
_
17 RELIABILITY | ACCOUNTABILITY
SRI Base (Denominator) for Normalization
• Normalization Base
Use TADS inventory (200 kV and above) for Tloss_base
o Yearly AC Circuits and Transformers inventory data
oAverage MVA rating for each voltage class (see next slide)
Use unit MW Ratings in ESD as Gloss base
o ESD – Electricity Supply and Demand database
• Aggregation level
Interconnection
NERC -Wide
18 RELIABILITY | ACCOUNTABILITY
SRI Base (Denominator) for Normalization (2)
• Average MVA capacity for AC Circuits o 765 kV → 3000 MVA
o 500 kV → 2000 MVA
o 345 kV → 1300 MVA
o 230 kV → 700 MVA
• Example of AC circuit loss event in EDI: 100 – 230kV, 40 – 345 kV, 10– 500 kV, 3 – 765 kV:
037.0
000,084,4000,151
3000332000344130010787002708
20003200010130040700100NT
19 RELIABILITY | ACCOUNTABILITY
Event Driven Index (EDI) - Example
• Using the combined risk index score SRI, the 2009 risk events summed to 506.117 points; the top five day’s SRI values were: 1/27/09 4.98 SRI points, 7/1/09 3.70 SRI points
1/28/09 3.67 SRI points, 2/11/09 3.32 SRI points
12/15/09 3.22 SRI points
• If EDIyear = success rate for BPS risk events,
then EDI2009 = 100 x (365 x 1000 – 506.117)/(365 x 1000)
≈ 99.8613
21 RELIABILITY | ACCOUNTABILITY
The Risk Control Reduction Cycle
• Develop actionable risk control steps.
• Solve the problems to eliminate potential risks to reliability.
• Prioritize the risk clusters to find those risks which are the most severe.
• Find potential risks to reliability.
Risk Cluster Identification
Prioritization
Actionable Risk Control
Steps
Solve Problems
Intelligenceand
Analysis
22 RELIABILITY | ACCOUNTABILITY
IRI Concept
Event Driven Index (EDI)
Measures Risk from
Major System Events
Standards/Statute
Driven Index (SDI)
Measures Risks from Severe Impact
Violations
Condition Driven Index (CDI)
Monitors Risk from Key Reliability Metrics
Based on event severity
risk index (SRI) values
and turns into an
availability index
Uses the roster
of reliability
metrics
developed by
RMWG and
approved by
OC/PC
Identify a
subset of
standards that
have highest
impact to
reliability and
create an index
of standards
violations
23 RELIABILITY | ACCOUNTABILITY
IRI Concept (2)
• BPS Integrated Reliability Index (IRI):
Event Driven Index (EDI): Based on event severity risk index (SRI) values
Condition Driven Index (CDI): Use a subset of metrics based on selection criteria
Standards/Statute Driven Index (SDI): Identify a subset of standards that have highest impact to reliability and create an index of standards violations
24 RELIABILITY | ACCOUNTABILITY
EDI Trends by Quarter
99.70
99.75
99.80
99.85
99.90
99.95
100.00
Even
t Dri
ven
Inde
x (E
DI)
25 RELIABILITY | ACCOUNTABILITY
Standards/Statute Driven Index (SDI) Proposed Approach
• Severe Reliability Impact Statement (RIS)
RIS indicates significance of impact on BPS
• Uses Violation Risk Factor (VRF)
• Demonstrates Violation Severity Level (VSL)
• Similar to daily SRI calculation
• Almost 4 year history violation history of 4,410 confirmed violations
26 RELIABILITY | ACCOUNTABILITY
SDI Calculation
• SDI = (Total Compliance - ∑(wV∙NV/NR))/(Total Compliance)
• Range from 0 to 100
• Total Compliance = 1.0 * Number of Days in a specific period
• wV = weighting of a particular high risk req. violation
• NV = number of violations for the selected high risk req.
• NR = number of registered entities required to comply with the high risk req.
27 RELIABILITY | ACCOUNTABILITY
SDI Calculation Example
• SDI = 100 ∙ (Total Compliance - ∑(wV∙NV/NR))/(Total Compliance)
• SDI = 100 ∙ (1.0 ∙ Days in a Quarter - ∑(wV ∙ NV/NR)) / (1.0∙Days in a Quarter)
• 1Q2009:
40 violations (PRC-005 R1)
RIS = Severe, VRF=High, VSL=Severe
A total of 335 TO, 828 GO registered entities
SDI = 100 x (1.0 x 90 - 0.038 x 40/(335+828))/(1.0 x 90)
= 99.99
29 RELIABILITY | ACCOUNTABILITY
Condition Driven Index (CDI)
• Uses metrics approved by OC/PC
• Applies SMART criteria to rank the relative importance and weighting for performance
• 5 trend ratings are determined per metric performance Significant improvement
Slight improvement
Inconclusive
Slight Deterioration
Significant Deterioration
30 RELIABILITY | ACCOUNTABILITY
Possible IRI Attributes
• Scale from 0 to 100
• 100 would indicate a perfect performance
• Weighting should be developed and can be adjusted
• Aggregation at NERC, Interconnection and Region levels
• Reporting period – targeting quarterly, reported at year end
• Trial indicators until sufficient history is experienced
31 RELIABILITY | ACCOUNTABILITY
IRI Objectives
•Inform industry leaders
•Increase transparency
•Quantify action effectiveness of risk reduction
•Meaningful bulk system performance trends
•Guidance on improving system reliability
•Support with risk‐informed decision making
32 RELIABILITY | ACCOUNTABILITY
Working with EIA and Sandia
• EIA’s and Sandia's statistical analysis experience and risk-control technologies Leverage metric development experience for the Nuclear
Regulatory Commission (NRC) and the National Aeronautics and Space Administration (NASA)
Statistical significance and confidence interval determination
Integrated strategy to apply science, technology, and engineering capabilities
33 RELIABILITY | ACCOUNTABILITY
IRI Future Steps
Present
• Severity Risk Index
• Adequate Level of Reliability metrics
• TADS
• GADS
• Event Analysis Database
IRI Process
• Statistically link reliability reduction cause & effect
• Link event, precursor indicators, and outage datasets to explore initiating events
• Find top initiating events
• Develop reliability index framework
Future
• Use IRI to quantitatively measure BES reliability
• Focus on improving top initiating event performance
• Help focus industry on relevant reliability risks to improve BES reliability