Real-time load profiling as an energy diagnostic tool

Rusty McCloud, MeterSmart Services

Reliable, timely energy consumption data, collected at specific time intervals, is critical to the efficient operation of any facility in today’s tough energy market. Complex commercial and industrial electrical systems, like anything else, experience periodic failure—a condition the facility energy manager may not even be aware of for hours, days or even longer. A close examination of the interval data comprising the facility’s load profile, however, will alert the experienced eye to any potential anomaly in electrical system performance—indicating that a problem has, in fact, already occurred or may happen in the near future.

Load profiling in review

Whether performed in-house or subcontracted to outside vendors, load-profiling services typically offer snapshots of customer energy use collected in 24-hour intervals, which is an adequate time window for most operating conditions. For a number of reasons, large commercial and industrial (C&I) customers are seeing the need for historical load-profile information.

Customer load-profiles have recently become accessible on password-protected Web sites operated by serving utilities or by third-party service providers. Customers can access their energy data on a 24/7 basis, viewing load profile information for the previous 24-hour period or in 15-minute intervals collected only minutes before. When such “real time” information is needed, the meter is queried and the new data appears almost immediately on the Web site in a choice of user-friendly report formats designed to characterize the source, nature, duration or other aspect of the event in question.

Real-time data comes at a price

When is real-time load profiling the right choice for the energy manager? Quicker feedback—typically collected in 15-minute intervals—is clearly necessary in cases where “time is money,” as, for example, with real-time pricing (RTP) programs, demand reduction or load control programs, self-generation, or in times of critical facility events.

Real-time monitoring may be needed on a continuous basis, seasonally or only during critical periods in the facility’s operating cycle. More frequent updates, however, are considered costly and therefore harder to justify. This is especially true for the most commonly used remote interval data retrieval medium, the telephony-based (landline) system. Landline systems offer higher reliability, but costs can run in the hundreds of dollars per month for 15-minute updates versus tens of dollars per month for daily updates. Other remote retrieval systems like cell phones, radios, pagers, satellite, Internet-based and fixed-network systems have improved but have not yet proven to be more reliable than telephony-based systems.

Real-time interval data is particularly valuable in jurisdictions where utilities offer hourly “real-time pricing” rates or tariffs based on a particular usage threshold or baseline. Energy consumption above or below baseline is billed or credited, respectively, at a specified marginal cost rate. Variations on RTP programs offered by utilities include hour-ahead pricing or some combination of day- and hour-ahead pricing.

Regardless of the RTP program chosen by a customer, the energy manager needs to know exactly where the current usage level is relative to the established baseline. Real-time load profiling is the tool that gives the energy manager critical visibility into the whole process, preventing unnecessarily high usage at higher prices or allowing under-baseline savings to be realized.

In many cases, the real-time pricing participant is concerned only with specific time blocks during the day, or with collecting energy data at specific intervals only as needed. Customer-initiated refreshes of the interval data may be generated from a Web browser, allowing the added flexibility of setting the data collection start-stop time whenever desired, followed by 15-minute updates. The customer determines when to begin frequent polling of the billing meter and pays only for the block of time that is scheduled. Some RTP programs even generate an alarm whenever new prices exceed a pre-set threshold value. This type of “turn on a dime” response to rapidly changing market conditions is impossible without load profiling, data processing and display of energy patterns collected in near real time.

Demand reduction and self generation

Many utilities offer demand-side programs that encourage energy managers to curtail their consumption during peak periods through demand credits or the opportunity to sell unused capacity back to the utility whenever possible. Demand-side management programs come in many flavors, but all require the energy manager to have a clear and up-to-date picture of where current facility demand stands in relation to the contracted base level.

Back-up generators installed for emergency purposes are typically sized to provide sufficient generating capacity to cover essential load requirements. Back-up generators that are only run during monthly operational tests can also be used during high marginal price periods or during demand reduction periods as well, providing a cost-effective alternative while never actually curtailing load. The load profile allows the energy manager to verify that the back-up generator actually started and went online, while simultaneously monitoring operations during the curtailment period. Real-time updates are important whenever generators are used to curtail load to the utility.

Critical events

Many facilities use interval recorders installed on the billing meter or, alternatively, submeters to monitor various segments of the process, as well as the total facility. This interval load profile data may be used to “benchmark” components in the facility or even across multiple facilities.

As a diagnostic tool, load profiling allows the energy manager to identify and correct operational problems before they get worse, and in some cases before they even happen. The ability to request real-time updates during these times is an important element in the energy manager’s flexible response to changing real-world operational and market conditions. How often the data is collected—whether in daily time slices or in 15-minute intervals—ultimately depends on the needs of the application and the costs involved.

It, therefore, behooves facility managers to thoroughly evaluate their internal energy monitoring needs and to adopt the most cost-effective solution available. One option certainly worth considering is to outsource the whole process to an experienced third-party supplier whose load profiling, information processing and display services can be custom-tailored to match the user’s current and future energy management needs.

McCloud is a civil engineering graduate of Texas A&M University and a registered professional engineer in the state of Texas. As MeterSmart Services’ vice president of operations, he was instrumental in the design, configuration and installation of MeterSmart’s MV-90 based data collection system.

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