According to the U.S. Department of Energy (DOE), 27 states and the District of Columbia have a renewable-portfolio standard—a policy requiring electricity providers to obtain a minimum percentage of their power from renewable-energy resources by a certain date—while five states have nonbinding goals for adoption of renewable energy (http://bit.ly/RPS_DSIRE). In those places, interest in demand response (DR) is growing.

DR is a set of activities to reduce or shift electricity use in response to supply conditions, with the goal of improving electric-grid reliability and managing customer electricity costs. Automation helps to improve the performance of DR programs by allowing responses to be more repeatable and reliable.

This article discusses Open Automated Demand Response (OpenADR), an information-exchange specification developed by the Demand Response Research Center (DRRC) at Lawrence Berkeley National Laboratory that enables fully automated DR. OpenADR uses utility-provided price, reliability, or DR-event signals to trigger preprogrammed energy-management strategies automatically.¹

This article also discusses the ancillary-services market. Ancillary services support power systems by helping to maintain power quality, reliability, and security. In California, California Independent System Operator (CAISO) purchases four types of ancillary-service products: regulation up, regulation down, spinning reserve, and non-spinning reserve.

Lastly, the article discusses pilot studies in which facilities participated in retail DR programs and wholesale ancillary-services markets and identifies research needed for widespread adoption of this approach.

OpenADR
OpenADR consists of two parts: a demand-response automation server (DRAS) and a DRAS client, also known as an OpenADR client (Figure 1).² Hosted by a utility or independent system operator, the DRAS publishes signals that notify an electricity customer of DR events. Embedded in or connected to the customer’s building-control system, the DRAS client listens to the signals, initiating preprogrammed control strategies in response.

Ancillary Services
Regulation energy is used to control system frequency, which can vary as generators access a system. Generators must respond to automatic-generation-control (AGC) signals to increase or decrease their operating levels, depending on the service—regulation up or regulation down—they provide.

Spinning reserve is unloaded capacity of units connected to or synchronized with the grid that can deliver energy in 10 min and run for at least two hours. Non-spinning reserve is capacity that can be synchronized and ramp to a specified load within 10 min. Typically, resources are dispatched using the International Organization for Standardization’s automated dispatch system (ADS) in conjunction with an energy-management system.

Participating-Load Pilot
CAISO offers two programs for participation in the wholesale DR market in California: proxy demand response (PDR) and participating load (PL). PDR is a load or aggregation of loads capable of measurable and verifiable electric-energy-demand reduction. These resources submit bids to the wholesale day-ahead or real-time energy market and respond to CAISO dispatches. Verification is done using a 10/10 baseline (average load over the previous 10 eligible days) or an agreed-upon baseline for a direct-load-control-type program. PL is a load that can only provide non-spinning reserve and curtail loads through real-time-market dispatch. With PL resources, hourly forecasts of bids are used for verification.

In 2009, the DRRC worked with CAISO to place three automated-DR customers from retail markets in the PL program. The customers’ communication and controls infrastructure was unchanged. The results showed that individual facilities can meet PL requirements with the same DR strategies used for retail-DR-program participation.³

Figure 2 shows the architecture used to connect the three sites to CAISO's signals. The ADS dispatched DR resources through the DRAS. For awards dispatching, OpenADR messaging infrastructure was utilized to deliver DR signals to the facilities’ energy-management and control systems (EMCS).

Dual-meter-socket installations allowed the facilities to keep their revenue meter and facilitated the installation of a meter with a code-division-multiple-access (CDMA) chip for the transfer of electric-load data. CDMA technology transmitted radio signals over a cellular-based wireless network. Four-second telemetry infrastructure was installed at each facility, and data were communicated to CAISO, the DRAS, and the utility. CAISO used the data to make the operating reserves visible on the grid and to ensure the resource was meeting its minimum operating-reliability criteria at all times. The utility stored the telemetry and interval-meter data in a secure folder. The data were used for load and shed forecasting.

The DRAS used the data to dispatch preprogrammed control strategies to sustain the shed amount dispatched by CAISO.

Having participated in the utility's automated-DR program for at least two years, the facilities already had two-level DR strategies programmed into their EMCS. The operators of each facility were asked to re-evaluate their strategies and decide for how long and with which DR strategy they would participate.

The operators of one facility allowed the team to adjust DR strategies based on the load feedback received from the 4-sec telemetry. A DR strategy utilizing 4°F temperature-set-point adjustments with 1°F increments was preprogrammed into the EMCS. During the resource-request period, forecasted bid level (target shed level) and measured load shed (current load level) were compared, and adjustments to temperature set points were requested automatically to sustain forecasted bid levels. Figure 3 shows how target shed level was maintained using measured sheds.

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