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Reliability Indicators
 
About This Metric
 
SRIbps
SRIbps is a metric in which the load loss component only captures load loss resulting from transmission or generation sources, notably the bulk power system. All other components of SRIbps are the same as the previously published and discussed SRIOLD. SRIbps does not take in account load lost due to distribution system sources.  Therefore this approach corrects the effects that arise from use of Form OE-417 data, as discussed above.
SRIbps  = [(RPL) × wL × (MWL) + wT × (NT) + wG × (NG)] X 1000
Where,
SRIbps           =              Severity Risk Index for specified event (assumed to span one day),
wL                =              60% , weighting of load loss,
MWL            =              normalized MW of bpsL in percent,
 
 
Where,
 
        =   load loss due to transmission or generation sources (MW) for the day
   = daily peak load (MW) is aggregated at NERC level obtained from FERC
 = Total Customer served for the day obtained from IEEE benchmark data
        = Customers Interrupted due to transmission or generation sources for the    day obtained from IEEE benchmark data
 
wT                =              30% - weighting of transmission lines lost,
NT                =              normalized number of transmission lines lost in percent obtained from TADS reports
 wG              =              10% - weighting of generators lost,
NG                =              normalized number of generators lost in percent obtained from GADS reports
 RPL             =              load Restoration Promptness Level:
                                 RPL = 1/4, if TCAIDI < 50,
 RPL = 2/4, if 50 <= TCAIDI < 100,
 RPL = 3/4, if 100 <= TCAIDI < 200,
 RPL = 4/4, if TCAIDI >=200.
 
Additional information on formula and weighting factors above can be found at http://www.nerc.com/docs/pc/rmwg/SRI_Equation_Refinement_May6_2011.pdf
 
Metric Definition Document
SRI Enhancement Whitepaper can be found at: http://www.nerc.com/comm/PC/Performance%20Analysis%20Subcommittee%20PAS%202013/SRI%20Enhancement%20Whitepaper.pdf
 
 

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