Patent Application
20230052163
This application relates to the field of building automation systems and, more particularly, to management of field devices for the building automation systems.
Building automation systems encompass many field devices, widely dispersed throughout a facility, that aid in the monitoring and control of various aspects of building operation, such as comfort, reliability, and energy savings. Examples of building automation systems include security systems, fire safety systems, lighting systems, and heating, ventilation, and/or air conditioning (“HVAC”) systems. The field devices of a building automation system utilize control mechanisms to maintain high precision for these monitoring and control features. One way to measure the performance of a control mechanism is to observe a settling time of a step response. The response may be eyeballed by a technician from a trend plot or determined by a separate data acquisition and processing system.
Currently, there is a problem with technician managing a field device of a building automation system, particularly for estimating controller response via visual inspection of a trend graph. Due to this difficulty, a technician could need a substantial amount of time for managing each device and, even then, the resulting performance from such maintenance may not be precise. In some cases, technicians may not even bother with any maintenance actions due to this difficulty, thereby leaving gaps for energy inefficiencies and poor safety responses. In addition, there are directions in the American Society of Heating and Air-Conditioning Engineers (“ASHRAE”) standards, for example with respect to fume hoods, to periodically assess and monitor the performance within a building automation system. With a typical project having 100+ operations (i.e., 50+ labor hours for the project), a technician or operator can be under substantial pressure to assess and service the performance of such operations more quickly and accurately.
A technician may also experience problems with servicing operations by a separate data acquisition and processing system. For every operation, the technician may need to step through a manual process to collect relevant data and generate a graphical view of the performance. For higher performance and accurate systems, the data collection of relevant data would benefit from a separate data acquisition system. The technician may then visually analyze the graphics, or analyze the data values directly, to assess the estimated performance of the respective operation so that the technician can identify corrections. The technician would need to repeat the process until she or he reached some level of confidence in achieving the desired performance. Thus, even with a separate data acquisition and processing system, a technician or operator is under substantial pressure to assess and service the performance of field device operations quickly and accurately.
In accordance with one embodiment of the disclosure, there is provided a control performance measurement and management approach for a building automation system (“BAS”). The approach facilitates determination of a settling time of a control loop so that a lab, building operator, or safety officer may quickly and usefully measure control performance during periodic checks. Events of an object, which may change values based on determined criteria, may be configured to determine and otherwise manage the settling time of the control loop. The settling time may be determined based on the deviation of normal time, offnormal time, and monitoring time from normal. For some embodiments, the settling time may then become, and be recorded as, a property of the object. As a result, the approach determines the settling time of the control loop to allow a technician to tune or otherwise manage a control loop to a concrete value instead of eyeballing a trend plot. The approach may also be used for fault detection & diagnostic, particularly with respect to a high, low, and/or unstable loop, and save time for the technician to setup/commission the BAS.
For some embodiments, control performance may be quickly implemented and determined with an Event Enrollment Object, thus reducing the skill level required to assess and service the control performance. Control performance may also be detected onboard a device without any additional or outside equipment/resources. As a result, a technician may tune or otherwise manage control loops and get quick immediate feedback, thereby allowing the technician to make immediate adjustments to the control loops. For example, the control parameters may be automatically adjusted to achieve the desire settling time.
One aspect is a method for managing control performance of a building automation device. Variable data is received at a field device. A variable reference and a setpoint reference are identified, the variable and setpoint preferences corresponding to a control loop of the field device and associated with the variable data. A time delay normal period is identified based on expected oscillations of the variable reference, a first upper settling threshold associated with the setpoint reference is identified, and a first lower settling threshold associated with the setpoint reference is identified. An offnormal timestamp is generated based on the variable reference relative to a second upper settling threshold associated with the setpoint reference, a second lower settling threshold associated with the setpoint reference, or both. The second upper and lower settling thresholds are different from the first upper and lower settling thresholds. A normal timestamp is generated based on the variable reference relative to the first upper settling threshold and the first lower settling threshold. A settling time of the control performance is determined based on the normal timestamp, the offnormal timestamp, and the time delay normal period. One or more performance features of the field device are modified based on the determined settling time.
Another aspect is a building automation system for managing control performance of a building automation device. A field device is configured to receive variable data at a field device, in which the field device has one or more performance features modified by a settling time. The field device or a management device communicating with the field device are configured to perform the following functions. A variable reference and a setpoint reference are identified, the variable and setpoint references corresponding to a control loop of the field device and associated with the variable data. A time delay normal period is identified based on expected oscillations of the variable reference, a first upper settling threshold associated with the setpoint reference is identified, and a first lower settling threshold associated with the setpoint reference is identified. An offnormal timestamp is generated based on the variable reference relative to a second upper settling threshold associated with the setpoint reference, a second lower settling threshold associated with the setpoint reference, or both. The second upper and lower settling thresholds are different from the first upper and lower settling thresholds. A normal timestamp is generated based on the control variable data relative to the first upper settling threshold and the first lower settling threshold. The settling time of the control performance is determined based on the normal timestamp, the offnormal timestamp, and the time delay normal period.
The above described features and advantages, as well as others, will become more readily apparent to those of ordinary skill in the art by reference to the following detailed description and accompanying drawings. While it would be desirable to provide one or more of these or other advantageous features, the teachings disclosed herein extend to those embodiments which fall within the scope of the appended claims, regardless of whether they accomplish one or more of the above-mentioned advantages.
For a more complete understanding of the present disclosure, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, wherein like numbers designate like objects.
Various technologies that pertain to systems and methods that facilitate control performance measurement and management of a building automation system (“BAS”) will now be described with reference to the drawings, where like reference numerals represent like elements throughout. The drawings discussed below, and the various embodiments used to describe the principles of the present disclosure in this patent document are by way of illustration only and should not be construed in any way to limit the scope of the disclosure. Those skilled in the art will understand that the principles of the present disclosure may be implemented in any suitably arranged apparatus. It is to be understood that functionality that is described as being carried out by certain system elements may be performed by multiple elements. Similarly, for instance, an element may be configured to perform functionality that is described as being carried out by multiple elements. The numerous innovative teachings of the present application will be described with reference to exemplary non-limiting embodiments.
The system and method quickly and accurately assess the control performance of control loops of field devices within a BAS controller. Technicians may better tune control loops by giving immediate feedback to measure performance times and readjust loop tuning parameters. In addition, an operator may monitor control loop performance for other faults including, but not limited to, control instability, control variable too high, control variable too low, and other faults associated with terminal unit fault detection.
Referring to
For the illustrated embodiment of
For some embodiments, the BAS 100 may include one or more programmable logic controllers 116 for connectivity to components of a building level network (BLN) of the system 100. Each programmable logic controller 116 may connect the primary bus 102 of the MLN to a secondary bus 118 of the BLN. Each programmable logic controller 116 may also include management logic for switching, power quality, and distribution control for the BLN components. Some field devices 120, 124 may communicate directly with the network connection or secondary bus 118 of the BLN, whereas other field devices 122, 126 may communicate through, and perhaps be controlled by, another field device (such as device 120, 124).
In these illustrative embodiments, objects associated with the BAS 100 include anything that creates, processes, or stores information regarding data points, such as physical devices (controllers, field panels, sensors, actuators, cameras, etc.) and maintains data files, such as control schedules, trend reports, defined system hierarchies, and the like. The illustration of the BAS 100 in
The communication component 204 is configured to receive data associated with one or more points of a site from a corresponding field device of the BAS 100 and otherwise manage the field device. For example, the communication component 204 may receive data from field devices of the subsystems 112, 114. The communication component 204 may utilize wired technology for communication, such as transmission of data over a physical conduit, e.g., an electrical or optical fiber medium. For some embodiments, the communication component 204 may also utilize wireless technology for communication, such as radio frequency (RF), infrared, microwave, light wave, and acoustic communications. RF communications include, but are not limited to, Bluetooth (including BLE), ultrawide band (UWB), Wi-Fi (including Wi-Fi Direct), Zigbee, cellular, satellite, mesh networks, PAN, WPAN, WAN, near-field communications, and other types of radio communications and their variants.
The processor or processors 206 may execute code and process data received from other components of the device components 200, such as information received at the communication component 204 or stored at the memory component 208. The code associated with the BAS 100 and stored by the memory component 208 may include, but is not limited to, operating systems, applications, modules, drivers, and the like. An operating system includes executable code that controls basic functions, such as interactions among the various components of the device components 200, communication with external devices via the communication component 204, and storage and retrieval of code and data to and from the memory component 208.
Each application includes executable code to provide specific functionality for the processor 206 and/or remaining components of the management and/or field device 104-108, 120-126, 201. Examples of applications executable by the processor 206 include, but are not limited to, a control performance module 210 and an event enrollment module 212. The control performance module 210 manages the control performance measurement and management of a BAS including the generation of normal and offnormal timestamps as well as the determination if a settling time for a control loop. The event enrollment module 212 processes an event enrollment object, which includes information relating to the management of events for a BACnet system. The event enrollment object communicates a device notification message in response to the occurrence of a specified event. For some embodiments, the event enrollment object may be utilized for control performance by setting the event type of the object to floating limit. By specifying an event type of floating limit, normal, high limit, and low limit event states are utilized as well as setpoint reference, time delay normal, high differential limit, and low differential limit event parameters.
For some embodiments, a field device may include a proportional integral derivative (“PID”) controller to employ feedback or continuously modulated control. The PID controller continuously determines an error value or other differential. For the BAS 100, the field device includes a PID controller for precise control of temperature, pressure, flow, or any other physical property within a system. For example, the field device may be used to manage physical components, such as sensors, dampers, valves, and other controllers of the BAS. For BACnet devices in particular, the PID controller takes the form of an event enrollment object within a BACnet field device. An environmental reading may be compared to a determined setpoint, and a control process may generate a correct control signal based on the environmental deviation from the setpoint, for example, for a valve, heater, or damper.
Data stored at the memory component 208 is information that may be referenced and/or manipulated by an operating system or application for performing functions of the management and/or field device 104-108, 120-126, 201. Examples of data associated with the BAS 100 and stored by the memory component 208 may include, but are not limited to, control loop data 214 and control performance data 216. The control loop data 214 includes the control variable data and the setpoint reference data corresponding to a control loop of a field device. The control performance data 216 includes information generated and determined by the management and/or field device 104-108, 120-126, 201, such as the offnormal timestamp, the normal timestamp, and the settling time.
The device components 200 may include one or more input components 218 and one or more output components 220. The input components 218 and output components 220 of the device components 200 may include one or more visual, audio, mechanical, and/or other components. For some embodiments, the input and output components 218, 220 may include a user interface 222 for interaction with a user of the device. The user interface 222 may include a combination of hardware and software to provide a user with a desired user experience.
It is to be understood that
In particular, for this example, data may be stored for each of the sensors 304, actuators 306, controllers 308, or functions 310 that indicate the state, operation, or readings of each of these components, and this data may be stored in a database, such as control loop data 214, or other storage. This data may include multiple data points for each of these elements. This data is used by functions 310, controller 308, and the management device to operate and monitor the BAS 100, including control performance measurement and management as disclosed herein. Of course, these particular sensors, actuators, controllers, and functions are for purposes of illustration, but each of the particular process implementations can use data from its own sensors, actuators, controllers, or functions, as described below.
Referring to
The BAS 100 includes multiple field devices 120-126 and one or more management devices 104-108, 201. Each field device 120-126 is configured to receive the variable reference 406 and the setpoint reference 408. For some embodiments, the management device 104-108, 201 identifies a variable reference property corresponding to the variable reference 406 of the control loop and a setpoint reference property corresponding to a setpoint reference 408 of the control loop. For these embodiments, the management device 104-108, 201 or the field device 120-126 may identify the variable reference 406 and the setpoint reference 408 based on the variable reference property and the setpoint reference property.
The management device 104-108, 201 communicate with the field device 120-126 to facilitate management of control performance. The management device 104-108, 201, the field device 120-126, or a coordinated operation of both the management and field devices, is configured to perform the functions described below. Event parameters 410-418 are identified, timestamps 420, 422 are generated, a settling time 424 is determined, and one or more performance features of the associated field device or devices 120-126 are modified.
A time delay normal period 410 is identified based on expected oscillations of the variable reference 406, a first upper settling threshold 412 associated with the setpoint reference 408, and a first lower settling threshold 414 associated with the setpoint reference 408. For some embodiments, an event enrollment object for the field device 120-126 may be generated based on the time delay normal period 412, the first upper settling threshold 414, and the first lower settling threshold 414.
An offnormal timestamp 420 may be generated based on the variable reference 406 relative to a second upper settling threshold 416 associated with the setpoint reference, a second lower settling threshold 418 associated with the setpoint reference, or both. The second upper and lower settling thresholds 416, 418 are different from the first upper and lower settling thresholds 412, 414 since they are associated with different setpoint baselines. For some embodiments, the offnormal timestamp 420 may be generated based on a portion of the variable reference 406 transitioning outside of the second upper settling threshold 416, the second lower settling threshold 418, or both.
A normal timestamp 422 may be generated based on the variable reference 406 relative to the first upper settling threshold 412 and the first lower settling threshold 414. The normal timestamp 422 may be generated based on a portion of the variable reference 406 being maintained within the first upper settling threshold 412 and the first lower settling threshold 414 for the time delay normal period 410.
The settling time 424 of the control performance may be determined based on the normal timestamp 422, the offnormal timestamp 420, and the time delay normal period 410. For some embodiments, the settling time 424 of the control performance may be determined based on a difference of the normal timestamp 422 from the offnormal timestamp 420 and the time delay normal period 410. For example, the control performance settling time (TSettling) may be determined by extracting the offnormal timestamp (TOffnormal) and the time delay normal period (TDelayNormal) from the normal timestamp (TNormal) using the following formula: TSettling=TNormal−TOffnormal−TDelayNormal. For some embodiments, the settling time 424 of the control performance may be determined using a processing engine of the event enrollment object. For example, an event type of the event enrollment object may be configured as a floating limit with a specified time delay normal event parameter so that the event enrollment object may record values for the offnormal and normal timestamps 420, 422.
With the determined settling time 424 , the management device 104-108, 201 and/or the field device 120-126 have a baseline on how to adjust the performance values to satisfy the control performance of the control loop. Thus, one or more performance features of an associated field device 120-126 may be modified based on the determined settling time 424. For some embodiments, one or more performance features of the field device 120-126 may be modified by adjusting the control performance of the control loop based on the settling time 424. For some embodiments, one or more performance features of the field device 120-126 may be modified by recording the normal timestamp 422, the offnormal timestamp 420, and the settling time 424 at the management device 104-108, 201 over a period of time, and performing a historical analysis of the normal timestamps 422, the offnormal timestamps 420, and the settling times 424. For some embodiments, one or more performance features of the field device 120-126 may be modified by generating an alarm fault signal based on the settling time 424 indicating a failure of the control variable to stabilize relative to the first upper settling threshold 412, the first lower settling threshold 414, or both, for the time delay normal period. For embodiments where the management device 104-108, 201 generates the alarm fault signal, the alarm fault signal may be generated based on a portion of the variable reference 406 being detected outside of the first upper settling threshold 412, the first lower settling threshold 414, or both.
The settling thresholds are associated with setpoint baselines, which adjust for the control loop of each field device 120-126. In particular, the first upper settling threshold 412 and the first lower settling threshold 414 correspond to the high limit and low limit of a first setpoint 426. Likewise, the second upper settling threshold 416 and the second lower settling threshold 418 correspond to the high limit and low limit of a second setpoint 428.
As represented by
The applicable event state 430 at any given time may be based on the setpoint 426, 428 corresponding to the time, as determined by the setpoint reference 408. For example, as illustrated by example in
It should be noted that multiple offnormal states are illustrated in the example of
Referring to
Referring to
In addition to identifying the variable reference and the setpoint reference (706), a time delay normal period 410 is identified (710) based on expected oscillations of the variable reference 406. The management device 104-108, 201 may also identify (710) a first upper settling threshold associated with the setpoint reference 408 and a first lower settling threshold associated with the setpoint reference 408. The identification of the time delay normal period 410, the first upper settling threshold, and/or the first lower settling threshold may occur anytime during the operation 400 so long as they occur before the timestamp generations and settling time 424 determination described below.
An offnormal timestamp 420 is generated (712) based on the variable reference 406 relative to a second upper settling threshold associated with the setpoint reference 408, a second lower settling threshold associated with the setpoint reference 408, or both. The second upper and lower settling thresholds are different from the first upper and lower settling thresholds since the different groups of thresholds are associated with different setpoint baselines. For some embodiments, the offnormal timestamp 420 may be generated (712) in response to identifying the variable reference (706) or identifying the time delay normal period 410 (710). For some embodiments, the offnormal timestamp 420 may be generated (712), while identifying the variable reference 406 (706), in response to a portion of the variable reference transitioning (714) outside of at least one of the second upper settling threshold or the second lower settling threshold.
A normal timestamp 422 is generated (716) based on the variable reference 406 relative to the first upper settling threshold and the first lower settling threshold. For some embodiments, the normal timestamp 422 may be generated (716) in response to identifying the variable reference (706) or identifying the time delay normal period 410 (710). For some embodiments, the normal timestamp 422 may be generated (716), while identifying the variable reference 406 (706), in response to a portion of the variable reference 406 being maintained (718) within the first upper settling threshold and the first lower settling threshold for the time delay normal period 410.
The management device 104-108, 201, the field device 120-126, or the coordination of the management and field devices determines (720) a settling time 424 of the control performance based on the normal timestamp 422, the offnormal timestamp 420, and the time delay normal period 410. For some embodiments where an event enrollment object for the field device 120-126 is generated (702), the settling time 424 of the control performance may be determined (720) using a processing engine of the event enrollment object. In this manner, the management device 104-108, 201 and/or the field device 120-126 may efficiently leverage the existing processing engine of the event enrollment object for this particular function of the control performance approach. For some embodiments, the settling time 424 of the control performance may be determined (722) based on a difference of the normal timestamp 422 from the offnormal timestamp 420 and the time delay normal period 410.
One or more performance features of the field device 120-126 are modified (724) based on the determined settling time 424, i.e., in response to determining the settling time 424 (720). For some embodiments, the management device 104-108, 201 or the field device 120-126 may adjust (726) the control performance of the control loop based on the settling time 424. For some embodiments, the management device 104-108, 201 may record (728) the normal timestamp 422, the offnormal timestamp 420, and the settling time 424 at the management device 104-108, 201 over a period of time, and perform a historical analysis at the management device 104-108, 201 of the normal timestamps 422, the offnormal timestamps 420, and the settling times 424 recorded over the period of time. For some embodiments, the management device 104-108, 201 may generate (730) an alarm fault signal in response to the settling time 424 indicating a failure of the variable reference 550, 560, 650 to stabilize relative to the at least one of the first upper settling threshold or the first lower settling threshold for the time delay normal period 410. For embodiments where the alarm fault signal is generated (730), the management device 104-108, 201 may generate (732) the alarm fault signal in response a portion of the variable reference 550, 560, 650 being detected outside of at least one of the first upper settling threshold or the first lower settling threshold.
Referring to
For some embodiments, the user interface 222 may also receive high and low differential limit entries, corresponding to the first upper and lower settling thresholds 412, 414, at the event parameter section 840. For some embodiments, the event type 850 of the event enrollment object may also be specified, such as an event type of floating limit. Also, the management device 104-108, 201 or the field device 120-126 modifies one or more performance features of an associated field device 120-126 based on the determined settling time 424 so the above information about the event enrollment object 810 may be entered in such a manner as to indicate the type or types of performance features 860, such as an alarm fault detection. For yet other embodiments, the deadband 870 may be configured for the event enrollment object 810 to set tighter settling thresholds for the determination of the settling time.
Referring to
Referring to both
Those skilled in the art will recognize that, for simplicity and clarity, the full structure and operation of all data processing systems suitable for use with the present disclosure are not being depicted or described herein. Also, none of the various features or processes described herein should be considered essential to any or all embodiments, except as described herein. Various features may be omitted or duplicated in various embodiments. Various processes described may be omitted, repeated, performed sequentially, concurrently, or in a different order. Various features and processes described herein can be combined in still other embodiments as may be described in the claims.
It is important to note that while the disclosure includes a description in the context of a fully functional system, those skilled in the art will appreciate that at least portions of the mechanism of the present disclosure are capable of being distributed in the form of instructions contained within a machine-usable, computer-usable, or computer-readable medium in any of a variety of forms, and that the present disclosure applies equally regardless of the particular type of instruction or signal bearing medium or storage medium utilized to actually carry out the distribution. Examples of machine usable/readable or computer usable/readable mediums include: nonvolatile, hard-coded type mediums such as read only memories (ROMs) or erasable, electrically programmable read only memories (EEPROMs), and user-recordable type mediums such as floppy disks, hard disk drives and compact disk read only memories (CD-ROMs) or digital versatile disks (DVDs).
Although an example embodiment of the present disclosure has been described in detail, those skilled in the art will understand that various changes, substitutions, variations, and improvements disclosed herein may be made without departing from the spirit and scope of the disclosure in its broadest form.
