2009 Pacific Gas and Electric Company SmartAC Ancillary Services Pilot

In the summer of 2009, PG&E and Lawrence Berkeley National Laboratory (LBNL) implemented a pilot program designed to assess the feasibility of providing spinning and non-spinning reserves to the California Independent System Operator’s (CAISO’s) Ancillary Service (AS) market using PG&E’s SmartAC program, an air conditioner (AC) cycling or direct load control program. Spinning and non-spinning reserves are system resources designed to allow the system operator to rapidly balance supply and demand on the electric grid in case of forced outages occurring on the generation and transmission systems.

The requirements for providing spinning and non-spinning reserve using responsive loads (e.g., air conditioning (AC) direct load control) are evolving in the California market. The Western Electricity Coordinating Council (WECC), for example, currently prohibits provision of spinning reserve with responsive loads. WECC’s current requirement is that resources providing spinning and non-spinning reserves be fully operational within 10 minutes of being called by the system operator. Spinning reserves must, in addition, be synchronized to the grid and begin operation immediately. Both spinning and non-spinning reserves must be capable of sustaining operation at full output for up to 2 hours (though, in fact, both reserves are rarely operated for the full two hours). Finally, suppliers must provide real-time information to the CAISO indicating the status of the resources providing spinning or non-spinning reserves.

PG&E’s AC direct load control program (SmartAC) controls approximately 135,000 central air conditioners located in the Central Valley and other areas east of the California Coastal Range. PG&E’s SmartAC program includes two types of direct load control (DLC) devices: programmable communicating thermostats (PCTs) and direct load control switches (DLC switches). Both types of DLC devices were examined in this pilot.

PG&E’s Transmission Operations Center (TOC) schedules SmartAC load control operations using a secure computer terminal located in its center at 77 Beale Street, San Francisco.CA. The terminal is connected via the internet to a signal control computer operated by Cooper Power Systems in Minneapolis, MN. The computer creates and sends load control signals to AC direct load control devices through paging companies with service in the PG&E service territory. It is a one-way communications link. That is,signals are sent to the control devices from the central facility, but the control devices do not return communication acknowledging receipt of the signal or provide other information that would indicate the results of operations.