1 1 Substation Asset Strategy Kevin Dasso, Senior Director Engineering and Operations IEEE/PES Annual Substations Committee Meeting April 7, 2008

2 2 Outline About PG&E Challenges Project Activities Capital Investment Outlook Trends Bus Conversions Mission Substation Rebuild Questions

3 3 About PG & E PG&E serves 13 million people, or 1 out of every 20 people in the U.S. 70,000 Square Miles Service Territory, from Eureka in the north to Bakersfield to the south 5 Million Electric Customers 4 Million Gas Customers Transmission Voltages – 500, 230, 115, 70 & 60 kV Distribution Voltages – 35, 21, 17, 12 & 4 kV Substations ! PG&E Service Territory Map

4 4 Electric Transmission Investment Profile Fastest-growing area of the business Investment driven by: –System expansions as approved by the California ISO –Interconnections/upgrades to support new generation –Replacements, upgrades, and other life extension programs to maintain capacity –Reduction of grid congestion and Reliability Must Run contracts –Access to renewable generating resources

5 5 Challenges Aging Infrastructure –Replacements, upgrades, and other life extension programs to maintain line capacity “Experienced” workforce NERC standards compliance

6 6 Capital Expenditure Outlook Distribution Substation$245$207$209$206 Transmission Substation$338$308$314$341$361 Transmission Line$257$218$515$356 $402 Total (in $MM)$840$733$1,038$903$969 Projected capital expenditures average $900M for years : ($MM)

7 7 Trends –Capacity growth –Reliability enhancements –Aggregation of future planned work at each facility in order to effect wholesale reliability upgrades

8 8 Bus Conversions -- Distribution –The majority of existing distribution busses are single- bus New installations are designed with a ring bus ► Major equipment replacement or capacity expansion projects present opportunities to convert to ring bus

9 9 Bus Conversions -- Transmission –The majority of transmission busses are double-bus / single breaker New installations are designed with breaker-and- a-half (BAAH) bus ► Major equipment replacement or capacity expansion projects present opportunities to convert to BAAH bus Space constraints drive toward GIS technology

10 Mission Substation Rebuild Many aspects were considered : –Operating Philosophy –Planned area upgrades –Reliability indexes and Outage statistics –Load balancing on 115 kV sources –Load planning and fault current levels –Available floor space, and construction sequencing –Construction clearance considerations— load shifting and switching ability

11 Mission Substation Rebuild Existing Substation Configuration: –Built in 1947; expanded in 1958 –Indoor substation with 3 floors –Four incoming 115 kV underground cables –115 kV open-air ring bus and equipment, with wall bushings between rooms –12 kV is double-bus switchgear; multi-floor –15 radial feeders, 9 network feeders, 14 tie cables –Three 50MVA and two 35MVA transformers, forced-oil, in separated rooms

12 Mission Substation Rebuild External Building View

13 Mission Substation Rebuild Existing Single Line Diagram – 9 element Ring Bus Bank Line

14 Mission Substation Rebuild Existing Control Room

15 Mission Substation Rebuild New Substation Configuration: –Rebuild in place, rather than across the street –Replace all existing 12 kV switchgear with new, compact switchgear (frees up needed floor space) –Increase capacity -- replace the 5 existing transformers with new 75MVA standard size and add a 6th transformer -- doubles capacity to 450 MVA! –Reduce fault current levels -- only 2 banks in parallel –Replace 115 kV open air bus with GIS –Replace all relays and control with latest integrated schemes

16 Mission Substation Rebuild New Single Line Diagram – 6 bay BAAH (2 spare elements) Line Bank FUT Line Bank Line FUT Bank Line

17 Mission Substation Rebuild New Control Room (simulated)

18 Mission Substation Rebuild Conversion Timeline: – Switchgear replacement, in two phases –2008 Award GIS and EPC project contract –2010 Rebuild complete

19 Q & A