DISTRIBUTION STORM HARDENING AND RESILIENCY. Matt Shellenberger, P.E. American Electric Power

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1 DISTRIBUTION STORM HARDENING AND RESILIENCY Matt Shellenberger, P.E. American Electric Power

2 AMERICAN ELECTRIC POWER

3 DEFINITIONS» Hardening: improves the durability and stability of infrastructure to withstand the impacts of severe weather events with minimal damage EEI Before and After the Storm, January 2013» Resiliency: measures do not prevent damage; rather they enable facilities to continue operating despite damage and/or promote a rapid return to normal operations EEI Before and After the Storm, January 2013

4 THE CURRENT REALITY» High customer expectations for good reliability and short duration outages» Regulatory / political scrutiny has increased» Increased frequency of the biggest storm we ve ever had» Significant direct and societal costs for storm outages

5 EVENT TYPES TO HARDEN AGAINST» Wind above 60 mph Wind blows trees into line causing: conductor and pole failure Aeolian vibrations; galloping conductor; Tropical Storms and Category 1 Hurricanes (74-95 mph) Straight line winds (i.e. Derecho; down bursts ; etc.)» Ice & Snow precipitation Ice and heavy wet snows cause loads exceeding design criteria Ice load breaks conductors and poles, as well causing trees to fall onto the system Snow load primarily impacts trees near the system (and to the system, by extension)

6 SYSTEM LEVEL ACTIONS» Execute basic reliability / asset programs Cyclic vegetation management program in all locations Asset / Reliability Programs Circuit inspection & repair of deteriorated material & equipment Visual, EMF, Infrared inspection methods Sectionalizing improvement on all single & three phase Cyclic pole inspection / treatment / replacement Target aged poles Replacement of small wire (#4 and smaller) Basic infrastructure maintenance programs, consistently executed improve reliability.

7 DESIGNING BEYOND NESC» Increase the ice load (NESC rule 250 B) while holding the design tension fixed.» Grade B overload factors vs. increase ice loading.

8 LD-PRO 10 BUTTON MODE» Used Phase 2 to define the new Zone load conditions (NESC 250B).» Determine limiting spans in Phase 5 and Phase 6.» Design in Phase 9p and determine costs in Phase 10.» Trial and error method to find equivalent wind load for a given design criteria.

9 COMPARING THE OPTIONS I could see for miles and miles, I could see for miles and miles.. The Who Extreme ice wind 3ph new per mile 556AAC using max span % Loading pole Heavy NESC Zone, 250C 100mph, 250D 1" ice 40mph 96% 40' cl4 tangent pole (280' span) Medium NESC Zone, 250C 100mph, 250D.75" ice 40mph 100% 40' cl5 tangent pole (265' span) Light NESC Zone, 250C 100mph, 250D.75"ice 30mph 82% 40' cl 4 tangent pole (260' span) Corrosive Zone, 250C 150MPH wind, 250D.5" ice 30mph 95% 40' cl 2 tangent (180' span) Heavy NESC Zone, 250B- B Grade 90% 40' cl 3 tangent pole Medium NESC Zone, 250B- B Grade 86% 40' cl 4 tangent pole Light NESC Zone, 250B B-Grade 95% 40' cl 3 tangent pole Corrosive Zone, 250B B-Grade 95% 40' cl 2 tangent Heavy NESC Zone, 250B- C Grade 95% 40' cl 4 tangent pole Medium NESC Zone, 250B- C Grade 79% 40' cl 5 tangent pole Light NESC Zone, 250B C-Grade 82% 40' cl 4 tangent pole Corrosive Zone, 250B C-Grade 95% 40' cl2 tangent Light Plus, 100mph wind, 250B C-Grade 98% 40' cl2 tangent Heavy Plus, 1" ice, 250B C-Grade 91% 40' cl 2 tangent, 60" heavy braces on tangent Heavy Plus, 1.5" ice, 250B C-Grade 82% 40' cl 2 tangent, 60" heavy braces on tangent

10 NORMALIZING THE RESULTS (NO OLF) NESC Table values Grade B Grade C Strength factors for 250B Wood » NESC Heavy Grade C 28lbs/ft 2 ~ 107mph wind» NESC Heavy Grade B 35lbs/ft 2 ~117mph wind» AEP Heavy Plus (1 ice) Grade C 45lbs/ft 2 ~133mph wind

11 SAG AND TENSION.» Same tension with more ice = more sag, shorter spans, more vertical load, etc.» Deadends and anchoring are about the same.

12 INTERNAL AEP RECOMMENDATIONS» Heavy loading district (1/2 ice 40mph wind) upgrade to 1 ice / 40mph wind Equivalent to 0 ice / 133 mph wind 25%+ Increased structure strength 5% - 15% avg. increase in capital cost per structure Based on worst case as defined by ASCE ice/wind map applied in all locations (except light loading district).» Medium loading district (1/4 ice/ 40mph wind): upgrade to 1 ice / 40mph wind.» Light loading district (0 ice / 60mph wind): upgrade to 0 ice / 90mph wind. Note: Texas coastal region designed for 150 mph wind 12

13 CIRCUIT LEVEL ACTIONS» Target specific circuits Prioritize circuits using criticality algorithm Apply options by zone» Increase Automated Circuit Reconfiguration, Sectionalizing, Station Breaker capabilities» Expand Distribution SCADA

14 EPRI RESILIENCY STUDY» Three year project to determine ways to strategically design components of the distribution system to fail in a certain order to prevent the most time consuming repairs to be prevented.» Items being evaluated: Spacer Cable Construction Third party attachment impact Conductor slippage Pole Impact Loading Insulator Pin tests Crossarms and braces (tangents and deadends) Neutral attachment test.

15 DECIDING ON A FAILURE ORDER Possible order of failure 1. Insulator ties slip or swing to relieve impact load. Similar to transmission swinging suspension insulator. 2. Break the deadend crossarm. 3. Break inline crossarms / shear post insulators. 4. Break the pole Equipment must still meet NESC minimums» Design poles to AEP Heavy Plus (1 of ice)» Design remaining equipment to NESC minimums» How to prevent pre-mature failure of mechanically fused components under day to day loading.

16 RISKS» Doing nothing may lead to increased regulatory scrutiny» Corporate focus / commitment must be long term» Additional regulatory support may be needed for funding» Culture beats strategy, every time It s worked OK this way before Non-standard materials and practices are prevalent» Resources are necessary for large scale implementation» Customer may resist facility location and maintenance requirements» Joint-users may resist additional costs

17 MEASURING RESULTS» Comparative analysis of storm performance between improved and non-improved circuits» Historic vs. post-improvement performance» Overall system reliability change

18 NEXT STEPS» Develop final design rules Keeps maximum design tensions same? Apply new design rules in Distribution Design Studio» Decision: Implement hardening design criteria for all new and replacement facilities system-wide - 25% increase in 5%-15% increase in cost - Next Step: Evaluate alternative materials

19 QUESTIONS????

20 THANK YOU