Systems and methods for adjusting operation of a building management system based on determination whether a building equipment is in steady state
A building management system includes connected equipment and a predictive diagnostics system. The connected equipment is configured to measure a plurality of monitored variables. The predictive diagnostics system includes a communications interface, a steady state detector, a controller. The communications interface is configured to receive samples of the monitored variables from the connected equipment. The steady state detector is configured to recursively update a mean and a variance of the samples each time a new sample is received, identify whether each of the samples reflects a steady state or a transient state of operation of the connected equipment using the mean and the variance, and associate each of the samples to the steady state or the transient state as identified. The controller is configured to adjust an operation of the connected equipment based on the steady state or the transient state as identified.
1. A method in a building management system, the method comprising:
receiving samples of one or more measured variables from building equipment;
recursively updating a mean and a variance of the samples;
determining whether the building equipment is operating in a steady state or operating in a transient state using at least one of the mean or the variance; and
adjusting operation of the building management system based on determining whether the building equipment is operating in the steady state or operating in the transient state.
2. The method of claim 1 , further comprising:
building a model for predicting performance of the building equipment using only samples associated with the steady state; and
adjusting operation of the building management system using the model.
3. The method of claim 1 , further comprising:
recursively updating a slope of the mean and a slope of the variance;
combining the slope of the mean and the slope of variance to generate a combined slope; and
determining whether the building equipment is operating in the steady state or operating in the transient state using the combined slope.
4. The method of claim 3 , further comprising:
determining whether the combined slope is less than a threshold;
determining whether a second derivative of the variance is positive; and
in response to determining that the combined slope is less than the threshold and that the second derivative of the variance is positive, determining that the building equipment has switched from operating in the transient state to operating in the steady state.
5. The method of claim 3 , further comprising:
determining whether the combined slope is greater than a threshold;
determining whether a second derivative of the variance is negative; and
in response to determining that the combined slope is greater than the threshold or that the second derivative of the variance is negative, determining that the building equipment remains operating in the transient state.
6. The method of claim 3 , further comprising:
determining whether the combined slope is greater than a threshold; and
in response to determining that the combined slope is greater than the threshold, determining that the building equipment has switched from operating in the steady state to operating in the transient state.
7. The method of claim 3 , further comprising:
determining that the building equipment has switched between operating in the steady state and operating in the transient state based on the combined slope.
8. A device in a building management system, the device comprising:
one or more circuits configured to implement operations comprising:
receiving samples of one or more measured variables from building equipment;
recursively updating a mean and a variance of the samples;
determining whether the building equipment is operating in a steady state or operating in a transient state using at least one of the mean or the variance; and
adjusting operation of the building management system based on determining whether the building equipment is operating in the steady state or operating in the transient state.
9. The device of claim 8 , the operations further comprising:
building a model for predicting performance of the building equipment using only samples associated with the steady state; and
adjusting operation of the building management system using the model.
10. The device of claim 8 , the operations further comprising:
recursively updating a slope of the mean and a slope of the variance;
combining the slope of the mean and the slope of variance to generate a combined slope; and
determining whether the building equipment is operating in the steady state or operating in the transient state using the combined slope.
11. The device of claim 10 , the operations further comprising:
determining whether the combined slope is less than a threshold;
determining whether a second derivative of the variance is positive; and
in response to determining that the combined slope is less than the threshold and that the second derivative of the variance is positive, determining that the building equipment has switched from operating in the transient state to operating in the steady state.
12. The device of claim 10 , the operations further comprising:
determining whether the combined slope is greater than a threshold;
determining whether a second derivative of the variance is negative; and
in response to determining that the combined slope is greater than the threshold or that the second derivative of the variance is negative, determining that the building equipment remains operating in the transient state.
13. The device of claim 10 , the operations further comprising:
determining whether the combined slope is greater than a threshold; and
in response to determining that the combined slope is greater than the threshold, determining that the building equipment has switched from operating in the steady state to operating in the transient state.
14. The device of claim 10 , the operations further comprising:
determining that the building equipment has switched between operating in the steady state and operating in the transient state based on the combined slope.
15. A building management system comprising:
one or more processors; and
one or more computer-readable storage media having instructions stored thereon that, when executed by the one or more processors, cause the one or more processors to implement operations comprising:
receiving samples of one or more measured variables from building equipment;
recursively updating a mean and a variance of the samples;
determining whether the building equipment is operating in a steady state or operating in a transient state using at least one of the mean or the variance; and
adjusting operation of the building management system based on determining whether the building equipment is operating in the steady state or operating in the transient state.
16. The system of claim 15 , the operations further comprising:
building a model for predicting performance of the building equipment using only samples associated with the steady state; and
adjusting operation of the building management system using the model.
17. The system of claim 15 , the operations further comprising:
recursively updating a slope of the mean and a slope of the variance;
combining the slope of the mean and the slope of variance to generate a combined slope; and
determining whether the building equipment is operating in the steady state or operating in the transient state using the combined slope.
18. The system of claim 17 , the operations further comprising:
determining whether the combined slope is less than a threshold;
determining whether a second derivative of the variance is positive; and
in response to determining that the combined slope is less than the threshold and that the second derivative of the variance is positive, determining that the building equipment has switched from operating in the transient state to operating in the steady state.
19. The system of claim 17 , the operations further comprising:
determining whether the combined slope is greater than a threshold;
determining whether a second derivative of the variance is negative; and
in response to determining that the combined slope is greater than the threshold or that the second derivative of the variance is negative, determining that the building equipment remains operating in the transient state.
20. The system of claim 17 , the operations further comprising:
determining whether the combined slope is greater than a threshold; and
in response to determining that the combined slope is greater than the threshold, determining that the building equipment has switched from operating in the steady state to operating in the transient state.