Pacific Gas & Electric Company
MTS: Evolution of the Electric Distribution System
Manho Yeung,
Senior Director, System Planning and Reliability
PG&E
October 15, 2014
1
PG&E Distribution System
Service Territory
 70,000 square miles with diverse topography
 5.5 million electric customers
 2013 peak demand about 21,000 MW
 Over 50% of electric supply from
non-greenhouse gas emitting facilities
Distribution Grid
 3200 distribution lines
 142,000 miles of distribution lines
 1.1 million distribution line transformers
 150,000 fuses
 14,500 voltage devices
 6,900 line reclosers
2
Integrating DER into the Distribution Grid
DG in PG&E System
1800
Distributed generation is growing
exponentially
1600
DG Adoption
 Total installed DG capacity = 1,647 MW
1400
 Total installed DG customers = 133,000
Megawatts
1200
 System penetration of DG Capacity = 8% of PG&E
system peak demand
1000
800

8% of distribution feeders have > 15% penetration*

3% of distribution feeders have >30% penetration

1% of distribution feeders have 100% penetration
600
Roof Top Solar
400
 Processing cycle time is 4 days from application
complete to Permission to Operate (PTO)
200
 Issued 4,000 PTO notices in August 2014 with a
projected 40,000 total for 2014
0
 No significant distribution upgrades required to
date
Year
* Penetration defined as installed generation divided by peak demand on feeder
3
Grid of Things to Integrate DER
The grid, with its many devices, serves as a platform to enable and
facilitate the integration of DERs
Protection devices to ensure safety
 Devices in RED such as breakers, reclosers, and fuses coordinate with DER protection schemes
Voltage regulation to ensure service quality
 Devices in GREEN are voltage devices that coordinate with DER load flow
 Most PGE feeders have voltage regulated by a substation Load Tap Changer and many have multiple
capacitors and tap changing regulators
Conductors and transformers to transmit power
 A portion of the feeder is considered “main line” where conductors are large
 Tap lines are used to connect customers and further distribute electricity
 Line transformers are used to step power down to secondary voltage to serve multi customers
 Most of the lines are economically sized for the load that they are serving
Line
transformer
SUB
Tap line
F
fuse F
R
F
regulator
Main line
F
capacitor
booster
recloser
breaker
4
Need an Intelligent Grid to Integrate DERs
Programs and initiatives that make the distribution grid more
intelligent, robust, reliable and affordable for our customers:
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Smart Meters
SCADA (supervisory control and data acquisition)
Sensors and monitors to further improve system operations
Volt/VAR optimization to automate voltage regulation and save
energy
Smart Inverters
FLISR (fault location isolation and service restoration) feeder
automation
Standardizing such as larger conductor and infrastructure
replacement for two way flows
Identify optimal locations and target DER (DR, EE, DG, storage)
to maximize customer benefits
5