Transmission Network Performance Report 2005 - National Grid

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DevelopmentsFY20053.1.2 Lightning AnalysisAs indicated in the preceding figures and tables, lightning has a very significantimpact on the system performance. Recognizing this importance, a lightningimprovement initiative was established in late FY2005. There are two interrelatedaspects to this work:• Lightning Analysis• Lightning Mitigating SolutionsThe overall intention is to learn more on how lightning impacts operationalperformance. A systematic analysis of historical faults (over the past 5 years) isbeing performed to derive a list of circuits that are especially prone to and exhibitpoor performance with respect to lightning. The intent is then to developstrategies and projects to address this poor or undesirable performance. Inaddition, strike location information is being identified for lightning-caused faults,to facilitate targeting and identification of potential damage. This would facilitateshorter repair times as well as mitigate the potential for future outages caused bylightning.Historically, northeastern United States is an area with relatively lower long-termexposure to lightning when compared to many other areas of the country, butwith this lower exposure comes a much greater variability in the amount oflightning storms from season to season. In the ten years studied for the NationalGrid USA service area average exposure densities (lightning density is thenumber of ground strokes/square kilometer/year) variances of ± 50 to 100% fromthe long-term average for a year are common, and some year-to-year changesare as high as 500%.26 National Grid Performance Report
FY2005DevelopmentsThe lightning density maps below illustrate the drastic nature of this year-to-yearvariability. Compare the density maps for CY2003 and CY2004. Hotter colorsindicate higher densities of lightning ground strikes.National Grid Performance Report 27
Page 1 and 2: National Grid Performance Reporti
Page 3 and 4: FY2005ContentsCONTENTSTransmission
Page 5 and 6: FY2005Transmission ReliabilityTrans
Page 7 and 8: FY2005Transmission Reliability1.3 P
Page 9 and 10: FY2005Transmission ReliabilityFigur
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Page 17 and 18: FY2005Transmission and CustomersTra
Page 19 and 20: FY2005Transmission and Customers•
Page 21 and 22: FY2005Transmission and Customers2.2
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Page 27: FY2005DevelopmentsFigure 3-2 shows
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Page 33 and 34: FY2005HVDCHVDCNational Grid Perform
Page 35 and 36: FY2005HVDCMost HVDC transmissions a
Page 37 and 38: FY2005Feedback andAdditional Inform
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Page 42: Feedback and Additional Information

Transmission Network Performance Report 2005 - National Grid

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