Automated Load Shedding Over Smart Grids | Automation.com

Automated Load Shedding Over Smart Grids

June 6, 2010 - The movement to reduce power usage and energy consumption among both consumers and businesses has never been stronger. This is especially true in the United States, where one year of energy consumption can now beat the energy production rate of the previous half-century.

In the U.S., businesses are rewarded with rebates and write-offs to replace inefficient systems with energy-saving “green” systems and technology. Heating and cooling systems are an ideal example, with the government offering worthwhile financial incentives for consumers who install solar, wind or geothermal systems.

U.S. energy providers, in the face of challenges like rising generation costs and expiring rate caps, are working with customers in unprecedented ways to reduce consumption and seek alternative ways to feed our power-hungry economy and country. Customers are experiencing a shift in the way that power companies control “when” power is being used. This active power management pushes power loads that would traditionally have occurred during peak power consumption periods into “valleys,” or low-energy usage cycles.

This helps to reduce brownouts, which can occur when energy usage exceeds the amount of energy that is available during these daily periods of peak consumption. Managing the power consumption and more evenly spacing it allows power companies to avoid scaling for additional power production.

Demand response instead relies on specific devices to reduce power on or completely shut down high-energy-usage machines and components during peak demand times, or otherwise balance usage between high- and low-demand cycles. This strategy is often referred to as load shedding, and when used effectively can help both the utility company and the customer to conserve energy and reduce costs.

Load Shedding and Building Automation
Load shedding usually begins with the energy provider or building owner. Often, the energy provider is responsible for signaling that it’s time for customers to make the necessary adjustments to power-consuming devices. This is accomplished by directly notifying a building engineer or resident, or forwarding an alert to a building automation system.

Load shedding becomes simpler with IP-based building automation systems. For commercial businesses, schools and large residential spaces such as apartment complexes, building automation has progressed to the point where most users have moved onto the IP layer. IP technologies give facility owners and managers the flexibility to migrate from legacy systems that locked them into specialized, proprietary systems, in favor of scalable systems with open standards.

The IP environment, or smart grid, also allows users to take advantage of a building’s existing network infrastructure. This not only does away with bundles of wires that are difficult to manage, but also creates a universal pipe to connect multiple systems and equipment components. It also provides an ideal platform to monitor operations and collect important data including run times and energy consumption.

Tying utility company alerts to the IP-based building automation system reduces the opportunity for human error, and can also help businesses and facilities generate data that confirms reduction of usage at peak times and explore ways to further improve energy efficiency.

How it Works
Utility companies typically trigger a closed relay to communicate load shed requests over the internet to building automation systems. The relay ideally communicates with any number of open-standard controllers connected to the facility’s network infrastructure to begin the process. Those controllers internally de-energize the relays to shed loads, and potentially communicate with sub-controllers within more complex, multi-layer building automation systems to drill deeper.

IP controllers and sub-controllers act as the bridge devices between the network infrastructure and the systems and machines that power the building. This typically includes lights, HVAC units, chillers, boilers and/or water pressure systems. Controllers with the appropriate I/O connections can also bring components tied to security, life safety and even AV systems onto the network. This might include digital and analog cameras, fire alarm panels and temperature sensors.

As a point of reference, a typical Barix building automation system will include at least one of its Barionet devices as the central I/O component. The Barionet 100 features two relays that can be used to turn machines and other building systems on and off for load shedding purposes. Sub-controllers such as the Barix R6 device add additional relays – six per R6 unit - to bring more devices onto the network. This connectivity enables a smart infrastructure to support load shedding.

The load shedding process mostly targets the highest energy-consuming systems. During peak power consumption hours, generally in the daytime, utility providers may signal their largest load-bearing customers to cut their lighting in half or reduce air conditioning cycles. In certain cases they may signal the facility to turn off power and switch to local usage. This might mean running building power through auxiliary systems including thermal ice storage, batteries or generators.

Smart systems based on a series of controllers and sub-controllers with multiple relays can be programmed so that systems within specific zones can be turned off at different times. A Barix system with one Barionet and five R6 units provide 32 relays. Relay #3 on each R6 may turn off lights on one side of the building for a specific period of time; when these lights come back, relay#4 can turn off the lights on the opposite wing.

This same philosophy can be applied to rooftop heating and cooling units, for example. The simple process of turning off some of the units at specific times will help shave energy usage. Rotating the units to cycle on and off every 15 minutes will ensure that none of the building spaces get too cool or warm, while keeping peak energy usage in check.

Data Collection and Centralized Monitoring
IP-based smart grids also support a centralized monitoring and reporting process, which gives energy-minded operators and engineers a valuable tool to measure effectiveness. The central controller or controllers, such as a Barionet, is usually responsible for aggregating and organizing the pertinent data related to the operation The number of controllers required is typically tied to the density of the system – the higher the I/O point count, the more controllers that are needed to compile and record the information.

IP systems allow building operators to check in on the operation from virtually anywhere. Pulling up the IP address for a specific controller from a browser is typically all that is required to retrieve and review the information, such as the success of a recent load shed. This will also give the operator a bird’s eye view of every controller and sub-controller in the network, which is helpful to pinpoint service issues, troubleshoot and respond accordingly.

The smart grid further improves data collection and reporting across the entire operation due its support of open standards. Gathering data from load shed events in an open protocol format is far simpler than retrieving data from several proprietary reporting tools in a legacy automation system.

It should also be noted that the support of standard encryption protocols such as AES 128-bit encryption can secure every device connected to the IP-based smart grid. This is essential for security, which is perhaps the largest single concern of operating an IP-based smart grid.

IP-based building automation systems also enhance redundancy. The Barionet, for example, can natively carry and report information to a secondary location if the central structure is temporarily offline. This will allow notification, alarm routing and general reporting related to load shedding and other processes continue uninterrupted.

Tying power and energy saving efforts to building automation has never been easier with smart grids. The flexibility of the smart grid and the many tools and devices available allow virtually any business or home-owner to build a manageable an effective system that matches their budgets.
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