1 Pacific Gas & Electric Company MTS: Evolution of the Electric Distribution System Manho Yeung, Senior Director, System Planning and Reliability PG&E October 15, 2014

2 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

3 Integrating DER into the Distribution Grid Distributed generation is growing exponentially DG Adoption  Total installed DG capacity = 1,647 MW  Total installed DG customers = 133,000  System penetration of DG Capacity = 8% of PG&E system peak demand  8% of distribution feeders have > 15% penetration*  3% of distribution feeders have >30% penetration  1% of distribution feeders have 100% penetration Roof Top Solar  Processing cycle time is 4 days from application complete to Permission to Operate (PTO)  Issued 4,000 PTO notices in August 2014 with a projected 40,000 total for 2014  No significant distribution upgrades required to date * Penetration defined as installed generation divided by peak demand on feeder

4 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 SUB R F F F F recloser breaker fuse capacitor regulator booster Main line Tap line Line transformer

5 Need an Intelligent Grid to Integrate DERs Programs and initiatives that make the distribution grid more intelligent, robust, reliable and affordable for our customers:  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