Integrating power monitoring systems

03/12/2014


Q: Of the power monitoring systems you have encountered, what percentage has been integrated into a BAS, BMS, or other engineered systems?

Figure 2: A double-ended switchboard with manual tie-breakers and power monitoring on both utility feeders allows last minute checks of the utility status prior to transfer.Shapiro: We have seen integrated systems in smaller facilities. The functionality of these systems as electrical power monitoring systems with power quality monitoring capability is limited. Usually dedicated power quality applications are required to view and analyze the information from power quality meters directly.

Strang: We are finding that more power monitoring systems are being incorporated into BMSs. However, of those we encounter, I would be surprised if more than 25% were truly seamlessly integrated. In most cases, only a real-time kW value or maybe current and voltage are brought over as individual data points.

Yoon: For the most part, we've specified power monitoring as stand-alone systems. While the ideal building would have a fully integrated BMS capable of real time, system-level power monitoring and demand response, actual implementation is rare.

The challenge has been overcoming our clients' skepticism regarding return on investment (ROI) versus perceived complexity and cost. While the Midwest historically had much lower electrical costs in comparison to the east and west coasts, there just hasn't been enough motivation here to overcome these perceptions. For every motivated triple net lease, single tenant building, or owner occupied building, there are a multitude of buildings where energy cost just isn't as much as a consideration. In multi-tenant buildings where base building electrical costs are simply passed through to the tenants as part of the annual operations costs, you're incredibly dependent on having a proactive building management and operations staff to help convince a building's ownership that making a capital investment in a power monitoring system makes sense.

Young: Almost all LEED buildings that have the measurement and verification credit, integrate the power monitoring system into the BAS/BMS. This provides the building management with a dashboard of the overall power consumption, but it also can provide the building occupants with information as to the potential energy savings being realized.

Q: What metrics can you provide to indicate quantifiable reasons for or against integrating power monitoring systems?

Shapiro: Data gathering speed and the granularity of the information in the event of an electrical failure is critical. Integrated systems are typically more of a basic type of system and lack the ability to achieve the sequence of events down to the synchronized millisecond, which is essential for failure analysis. Dedicated local area network (LAN) infrastructure as well as dedicated servers and dedicated human-machine-interfaces (HMIs) allow for the speed, clear graphics, data presentation, and analytical tools required to achieve the tasks required for the facilities we design and commission.

Strang: I have heard various percentages used over the years, such as a power monitoring system can save you 10% of your utility bill. Based on experience, I would say that savings should be easily achievable with a power monitoring system. The catch phrase is “you can’t reduce what you can’t measure.” I firmly believe many of the benefits of a power monitoring system are more intangible and harder to quantify. For example, trending of current or voltage waveforms with a high resolution power monitor (i.e., 256 samples/cycle or greater) can provide insight into transformer internal arcing, incipient ground faults, or harmonic overheating of neutrals. The value of predictive maintenance saving a large power outage could be very high depending on the criticality of the load.

Young: The cost of the power monitoring system integration into the BMS is often one of the deciding factors. Another metric is if integrating the systems significantly increases the complexity and maintainability of either system.

Q: How often are power monitoring systems integrated with demand response scenarios?

Shapiro: Facilities we design and commission typically are not part of demand response scenarios due to the critical nature of the facility.

Strang: We typically do not see power monitoring systems integrated with demand response scenarios unless they are dedicated systems for that purpose. I think there is a big future, though, for this application and we will see more of it. There are many demand response vendors with programs that can only benefit the end user by signing up to curtail load and be paid to do so.

Yoon: In most cases, we see power monitoring only being used by buildings to optimize their load profiles, to identify operational issues, and to control monthly electrical demand charges. Very infrequently will we see power monitoring integrated with a demand response program, even though it seems like it should be a logical extension. The primary hurdle to overcome is the perception of the risk associated with demand response. Most clients think of demand response as a singular program where they are going to be asked to curtail electrical usage when they need it the most. This serves to highlight a very clear gap in understanding of the available programs. It's very uncommon to come across clients who can explain the basic differences between emergency demand response, economic demand response, and real-time pricing. If we could better explain that there are multiple different versions of demand response with various different potentials for risk and reward that can be tailored to meet the needs of the client, the acceptance of these programs would dramatically increase.

As it is, we depend on education and advocacy from groups like the Building Owners and Managers Association (BOMA) to spread the message among building owners and operators. We see relatively little from the utility company side to promote these programs. This is a shame given that there's relatively minimal risk associated with many programs. For example, emergency curtailment calls by the regional transmission organizations for the Midwest are extremely rare. It's basically leaving easy money on the table.

Young: Almost all power monitoring systems are integrated when the owner contracts for demand response. The building system monitors and records the demand reduction as well as the time frame for the reduction. This can provide a separate, independent record of not only the level of reduction, but the time of the reduction.



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