Energy Profiles: BACnet Load Control, 61850, OpenADR, ZigBee, and C12.19 David Holmberg BACnet Utility Integration Working Group leader OASIS Profiles in Energy June 9, 2009
Energy Profiles in context Service levels (the control strategy) Communications (info model) Load control (or price) communications Feedback to the grid side Or bids
BACnet background The BACnet protocol is all about building controls and designed for monitoring systems, managing schedules, trending, controlling loads. BACnet has metering specific tools like the Accumulator and Pulse Converter objects. Ongoing work on a generic Meter object to allow for interoperable access from meters or meter gateways. BACnet has a specific Load Control object (LCO)
BACnet Load Control object The Load Control object (LCO) provides an interface to execute predetermined control actions and to view current load shed status (example) Load Control object does not specify how the electrical consumption is to be reduced or how consumption baselines should be determined. Three parameters may be written: Requested_Shed_Level Start_Time Shed_Duration LCO can be in one of four states: inactive, shed pending, shed compliant, or shed non-compliant. can be linked in a distributed, hierarchical fashion for controlling complex combinations of electrical loads
Using the LCO LCO “Requested_Shed_Level” can be a level or % shed or kW shed. LCO provides a way to communicate value to sub-systems/ devices, rather than commanding them with specific control actions. LCO provides for status to give feedback—will you shed? Are you shedding? (discovery, forecasting and DG) Implementing Prices-to-devices Do we use the LCO with a chiller? Isn’t it better to raise zone temperature and let the existing control algorithm reduce energy consumption? Temp Control (LC in terms of “don’t melt the chocolate”) Acceptable lighting reductions (service level) For unimportant loads (the pool pump) I’m not going to tell it to go to 50% power Has to be in the context of building operation.
ZigBee SEP ZigBee SEP details load control and price event signals for AMI DR and LC Cluster, Apdx. D Load Control Event: issuerID, DeviceClass (to allow directing event, e.g., HVAC, pool pump, lighting, EV, water heater, appliance), startTime, Duration, CriticalityLevel, TempOffset, TempSetpoint, AverageLoadAdjustmentPercentage, DutyCycle CancelEvent commands also Price Cluster Get and publish price commands Get Scheduled Prices PublishPrice format: providerID, Rate class, EventID, current time, price, units, currency, start time, duration, price ratio, alternate cost delivered.
61850, OpenADR, C12.19 Marty Burns’ cross-analysis of IEC 61850, OpenADR, ANSI C12.19 and LCO price and DR structures. “Common Objects for Pricing and Control Communications, EPRI 1018556” Begins with 61850 constructs and adds to them to include pieces from other standards. Goal: develop real time price rate structures and control signals in IEC 61850 formats for contributions to user groups and standards organizations C12.19 Table 11: Direct load control: command sent to modify the state of control points. Schedule: End Device programmed to modify state of control points at specific dates, recurring dates, period of the week or event detection. Condition: End Device modifies state based on magnitudes of metered quantities, price level (active tier), time of the day, period of the year or any other condition based on a Single Line Math expression. Prepayment: End Device modifies state based on a remaining credit.
61850 data classes Tariff Schedule Direct Load Control Market Bidder Bid Weather Consumption Event Energy Efficiency IAQ