METHOD FOR VERIFYING THE PLAUSIBILITY OF SENSOR INFORMATION IN A PLANT PROCESS

Abstract

An aspect of the invention relates to a method for verifying the plausibility of sensor information sensed by a sensor device associated with a plant process, in particular a water treatment process and/or a wastewater treatment process, wherein the sensor information relates to the plant process, the method comprising: receiving (S100), by a control unit, the sensor information; performing (S110), by the control unit, a verification model, the verification model determining an expected sensor information which the sensor device shall provide, wherein the verification model determines the expected sensor information based on at least one other information related to the plant process and having a relationship to the sensor information; comparing the expected sensor information with the received sensor information; and upon determining (S120) that the sensor information deviates from the expected sensor information, outputting (S130), by the control unit, a verification signal.

Claims

1-15. (canceled)

16. A method for verifying the plausibility of sensor information sensed by a sensor device associated with a plant process, in particular a water treatment process, wherein the sensor information relates to the plant process, the method comprising: receiving, by a control unit, the sensor information; performing, by the control unit, a verification model, the verification model determining an expected sensor information which the sensor device shall provide, wherein the verification model determines the expected sensor information based on at least one other information related to the plant process and having a relationship to the sensor information; comparing the expected sensor information with the received sensor information; and upon determining that the sensor information deviates from the expected sensor information, outputting, by the control unit, a verification signal.

17. The method of claim 16, wherein the at least one other information is not originated from the sensor device.

18. The method of claim 16, wherein the at least one other information is at least one of a second sensor information of a second sensor device associated with the plant process, a process parameter related to the plant process, a plant process constraint and a control activity related to the plant process.

19. The method of claim 16, wherein the verification model includes at least one rule for determining the expected sensor information based on the at least one other information.

20. The method of claim 19, wherein the at least one rule is determined based on historical data related to the plant process.

21. The method of claim 16, further comprising: in response to the verification signal, switching the control unit in a safe control mode for controlling the plant process.

22. The method of claim 16, further comprising: in response to the verification signal, initiating a maintenance procedure, in particular a comparison and calibration procedure, for the sensor device.

23. The method of claim 21, further comprising: in response to the verification signal, initiating a maintenance procedure, in particular a comparison and calibration procedure, for the sensor device; and after completing the maintenance procedure, switching the control unit from the safe control mode back to a normal control mode.

24. A control unit for controlling a plant process, in particular a water treatment process, the control unit being communicatively coupled to a sensor device associated with the plant process and sensing sensor information related to the plant process, the control unit being configured to: receive the sensor information; perform a verification model, the verification model for determining an expected sensor information which the sensor device shall provide, wherein the verification model determines the expected sensor information based on at least one other information related to the plant process and having a relationship to the sensor information; compare the expected sensor information with the received sensor information; and output a verification signal upon determining that the sensor information deviates from the expected sensor information.

25. The control unit of claim 24, wherein the at least one other information is not originated from the sensor device, wherein the at least one other information is at least one of a second sensor information of a second sensor device associated with the plant process, a process parameter related to the plant process, a plant process constraint and a control activity related to the plant process.

26. The control unit of claim 24, wherein the verification model includes at least one rule for determining the expected sensor information based on the at least one other information.

27. The control unit of claim 26, wherein the at least one rule is determined from historical data related to the plant process.

28. The control unit of claim 24, wherein the control unit is configured to switch in a safe control mode for controlling the plant process in response to the verification signal.

29. The control unit of claim 28, further configured to initiate a maintenance procedure, in particular a comparison and calibration procedure, for the sensor device, and to switch from the safe control mode to a normal control mode of the plant process, after receiving an indication that the maintenance procedure has been completed.

30. A computer program comprising instructions which, when the program is executed by a control unit for controlling a plant process, in particular a water treatment process, the control unit being communicatively coupled to a sensor device associated with the plant process and sensing sensor information related to the plant process, cause the control unit configured to: receive, by the control unit, the sensor information; perform, by the control unit, a verification model, the verification model determining an expected sensor information which the sensor device shall provide, wherein the verification model determines the expected sensor information based on at least one other information related to the plant process and having a relationship to the sensor information; compare the expected sensor information with the received sensor information; and upon determining that the sensor information deviates from the expected sensor information, outputting, by the control unit, a verification signal.

Description

[0040] These and other objects, features and advantages of the present invention will become more apparent upon reading of the following detailed description of preferred embodiments and accompanying figures. It should be understood that even though embodiments are separately described, single features thereof may be combined to additional embodiments.

[0041] FIG. 1 depicts a method for verifying the plausibility of sensor information in a plant process, and

[0042] FIG. 2 Depicts a process for defining at least one rule used by a verification model.

[0043] FIG. 1 schematically depicts a method for verifying the plausibility of sensor information in a plant process, e.g., a (waste) water treatment process. Some of the depicted method steps may be optionally and are depicted to provide a better understanding of the context the present disclosure. The method is depicted as a closed loop because it is continuously performed during execution of the plant process.

[0044] The plant process may be controlled based on data/information, in particular sensor information/readings, related to the plant process. The sensor information may be based on the sensor reading. For example, one or more sensor devices may provide sensor information related to the plant process to a control unit, wherein the control unit performs one or more control activities based on the sensor information. The sensor information may represent a value of a process parameter of the plant process. Further, the control unit may additionally consider the process stage of the plant process for performing said control activities.

[0045] A sensor device may be a process analyzer and/or a process probe which preferable continuously measures/reads a parameter related to the plant process, e.g., an oxygen concentration, a nitrate concentration etc. The sensor device may also be a non-analytic sensor, e.g., a water flow rate sensor, an air flow rate sensor, a pressure sensor. Both, the process analyzers, and non-analytic sensors may provide corresponding sensor information which may be used by the control unit to control the plant process.

[0046] In step S100 depicted in FIG. 1, sensor information of one or more sensor devices may be received. Optionally, the sensor information may be stored to provide for historical data. Further, the sensor information may be received by the control unit.

[0047] Moreover, the control unit may be configured to perform a verification model, wherein the verification allows determining an expected sensor information of a sensor device of the one or more sensor devices based on at least one other information related to the plant process and having a relationship to the sensor information of said sensor device. That is, the expected sensor information is determined from the context of the plant process in which the sensor device operates.

[0048] In step S110, the control unit performs the verification model to determine the expected sensor information.

[0049] Further, in step S120, the determined expected sensor information is compared to the actual received sensor information of the sensor device which is to be verified. In case the actual sensor information matches the expected sensor information, the plant process is continued as it is. That is no exceptional control activities are performed.

[0050] Upon determining that the actual sensor information deviates from the expected sensor information, a verification signal is output by the control unit in step S130. Based on the output of the verification signal in step S130, the control unit may switch into a fallback operation mode for controlling the plant process (step S140 in FIG. 1). The fallback operation mode may provide for safe operation of the plant process which might be based on a control strategy not relaying on the faulty sensor device. Furthermore, the verification signal may include information regarding specific fallback control activities to be performed by the control unit and/or the plant on which the plant process is running.

[0051] Furthermore, in step S150, the control unit may initiate a maintenance activity for a sensor device, e.g., a comparison/calibration activity. For example, the control unit may automatically activate a workflow procedure comparison/calibration of the sensor device and/or may electronically communicate to an operator that comparison/calibration of the sensor device is required. For this purpose, the control unit, the sensor device, and a calibration facility may be communicatively coupled with each other, e.g., through a cloud application. Furthermore, the verification signal may indicate the sensor device(s) for which the maintenance activity shall be performed.

[0052] In a first step of the comparison/calibration activity, the sensor information/sensor reading may be compared with a laboratory reading of a sample preferably taken at the location of the sensor device. In a second step, it is determined whether the sensor reading matches the laboratory reading. In case, both readings do not match, the sensor device is calibrated and/or repaired and/or exchanged and it is indicated to the control unit that the maintenance activity is completed. In case both readings match, it is also indicated that the maintenance activity is completed.

[0053] After completing the maintenance activity of the sensor device(s), the control unit may be switched back to a normal operation mode for controlling the plant process in step S170, provided that the control unit and/or the plant process was operated in the fallback operation mode (step S160).

[0054] In the following, examples of the at least one other information based on which the verification is performed are discussed in more detail.

[0055] Preferably, the at least one other information is at least one of a second sensor information of a second sensor device associated with the plant process, a process parameter related to the plant process, a plant process constraint and a control activity related to the plant process.

[0056] For example, the second sensor device may provide as second sensor information a sensor reading related to a dosage of a chemical applied in the plant process. Based on said dosage information, the verification model may determine an expected sensor information which the sensor device (first sensor device) shall provide/communicate, because applying the dosage of the chemical in the plant process may have a deterministic impact to the parameter reading by the first sensor device. Further, the dosage information may relate to time of day and the stage of the plant process. In another example, sensor information of similar sensor devices of parallel process/treatment lanes are compared. In a further example, a conductivity sensor reading may be used to verify a sensor information/sensor reading from an NH4-N sensor.

[0057] Moreover, a process parameter as the at least one other information may provide for a time-based relationship between the at least one other information and the sensor information. Specifically, historical data at a given time of the day may be the at least one other information. For example, the process parameter may be a consumption information of past periods, e.g., consumed energy for aeration and/or consumed chemicals. Further, if it is determined that the consumption determined from the sensor information deviates from the typical consumption information of past periods, e.g., example at the same time of the day, the verification signal is output. The verification signal may further indicate that the sensor device is likely to be faulty and/or that a sensor device sensing a process parameter having an effect on this process parameter, i.e., the consumption of energy for aeration or consumption of chemicals, is faulty. For example, if the current energy consumption for aeration deviates from an expected energy consumption, a sensor device sensing the oxygen and/or ammonium concentration might be faulty and thus, causing an inappropriate aeration control.

[0058] As a further example, the process parameter may be historical data related to a consumption of a chemical, e.g., a precipitant, at the same time of the sensor information and having similar flow rates.

[0059] Moreover, a plant process constraint as the at least one other information may provide for defining a relationship between a limitation the plant process and the sensor information. A plant process constraint may be a physical and/or a chemical constraint given by the plant process, e.g., by the physical layout of the plant running the plant process. For example, a sensor information related to a sensor reading of a flow rate or a change of a flow rate in the hydraulic system of the plant may be compared to an expected flow rate or change of flow rate based on the physical layout of the plant.

[0060] Accordingly, deviations between the expected flow rate and the measured flow rate (current sensor information) may cause the verification signal to be output. The verification signal may indicate that the sensor device communicating the sensor information is likely to be faulty.

[0061] Moreover, a control activity related to the plant process as the at least one other information may provide for defining a relationship of control activities with respect to the sensor information. A control activity may relate to modifying a control parameter influencing the plant process or a parameter of the plant process. For example, increasing the aeration energy in the plant process as a control activity should result in a decrease of an ammonium (NH4-N) sensor reading of a sensor device. Accordingly, if the current sensor reading does not decrease, the verification signal may be output. The verification signal may further indicate that the sensor device communicating the sensor information is likely to be faulty.

[0062] As a further example, the at least one other information may relate to the airflow demand in certain zones/stages of the plant process, e.g., a wastewater treatment process, which is compared to corresponding sensor information. Accordingly, a changing ratio between those air flow demands can be caused by a sensor device reading a NH4-N concentration. Specifically, a drifting NH4-N sensor reading towards higher reading will result in higher air demand in the corresponding lanes if the sensor device(s) is (are) implemented in a closed loop control structure. Moreover, the at least one other information and the sensor information may relate to a specific time of day

[0063] As a further example, on intermittent operated plants, when controlling the process to be in an aeration stage, it is expected that after a certain aeration time a sensor device reading the NH4-N parameter communicates 0 mg/L (expected sensor information). If the actual sensor information deviates from this sensor information, the verification signal is output to initiate a maintenance activity for the sensor device.

[0064] Preferably, the verification model includes at least one rule for determining the expected sensor information based on the at least one other information. Accordingly, the at least one rule defines a relationship or dependency between the at least one other information and the sensor information. In case the expected sensor information deviates from the sensor information, the control unit may assume that the at least one rule is violated which may cause the verification signal to be output. Moreover, the at least one rule may be deterministic. That is, the same input to the rule provides the same output, i.e., the same expected sensor information. Further, rules may be associated with each other allowing a fine-grained determination of the expected sensor information. Accordingly, the verification signal may be output if all associated rules are violated.

[0065] Moreover, the at least one rule may further define verification information to be issued with the verification signal. The verification information may indicate the sensor device which is probably faulty. This is particular useful for a case where the violation of a rule indicates that a sensor device other than the sensor device providing the sensor information with which the expected sensor information is compared is faulty.

[0066] Furthermore, the at least one rule may be defined by a user. For example, the control unit may provide a user interface allowing to define the at least one rule.

[0067] Preferably, the at least one rule is determined based on historical data (see step S100) related to the plant process or during a learning period. For example, the at least one rule may by determined by an artificial intelligence module being trained with the historical data.

[0068] Referring to FIG. 2, a process for defining the at least one rule used by the verification model is described in more detail. In step S210, one or more deterministic rules may be defined. A deterministic rule may be based on a relationship between a sensor information and the at least one another information. The deterministic rule may be defined by a user and stored in the control unit.

[0069] Alternative or additionally, one or more empirical rules may be defined. Empirical rules may be defined during a learning period and/or are based on historical date. For example, historical data stored in step S100 or other previously stored historical data.

[0070] In step S220, sensor devices and/or signals are defined for monitoring during a subsequent empirical relationship evaluation. In step S230, the defined sensor devices and/or signals are checked for correlations based on the evaluation which for example may be based on historical data. In case a correlation between sensor devices and/or signals has been found, a corresponding empirical rule is defined in step S240, wherein the rule defines a relationship between sensor devices and/or signals related to the plant process. The process results in at least one defined rule. The at least one rule may be applied to the verification model.

[0071] In the following, further features, characteristics and advantages of the invention will be described by means of items:

[0072] 1. A method for verifying the plausibility of sensor information sensed by a sensor device associated with a plant process, in particular a water treatment process and/or a wastewater treatment process, wherein the sensor information relates to the plant process, the method comprising: [0073] receiving (S100), by a control unit, the sensor information; [0074] performing (S110), by the control unit, a verification model, the verification model determining an expected sensor information of the sensor device based on at least one other information related to the plant process and having a relationship to the sensor information; [0075] comparing the expected sensor information with the received sensor information; and [0076] upon determining (S120) that the sensor information deviates from the expected sensor information, outputting (S130), by the control unit, a verification signal.

[0077] 2. The method of item 1, wherein the at least one other information is not originated from the sensor device.

[0078] 3. The method of item 1 or 2, wherein the at least one other information is at least one of a second sensor information of a second sensor device associated with the plant process, a process parameter related to the plant process, a plant process constraint and a control activity related to the plant process.

[0079] 4. The method of any one of items 1 to 3, wherein the verification model includes at least one rule for determining the expected sensor information based on the at least one other information.

[0080] 5. The method of item 4, wherein the at least one rule is determined based on historical data related to the plant process.

[0081] 6. The method of any one of the preceding items, further comprising: [0082] in response to the verification signal, switching the control unit in a safe control mode for controlling the plant process.

[0083] 7. The method of any one of the preceding items, further comprising: [0084] in response to the verification signal, initiating a maintenance procedure, in particular a comparison/calibration procedure, for the sensor device.

[0085] 8. The method of item 6, further comprising: [0086] in response to the verification signal, initiating a maintenance procedure, in particular a comparison/calibration procedure, for the sensor device; and [0087] after completing the maintenance procedure, switching the control unit from the safe control mode back to a normal control mode.

[0088] 9. A control unit for controlling a plant process, in particular a water treatment process and/or a wastewater treatment process, the control unit being communicatively coupled to a sensor device associated with the plant process and sensing sensor information related to the plant process, the control unit being configured to: [0089] receive the sensor information; [0090] perform a verification model, the verification model for determining an expected sensor information of the sensor device based on at least one other information related to the plant process and having a relationship to the sensor information; [0091] compare the expected sensor information with the received sensor information; and [0092] output a verification signal upon determining that the sensor information deviates from the expected sensor information.

[0093] 10. The control unit of item 9, wherein the at least one other information is not originated from the sensor device; and/or [0094] wherein the at least one other information is at least one of a second sensor information of a second sensor device associated with the plant process, a process parameter related to the plant process, a plant process constraint and a control activity related to the plant process.

[0095] 11. The control unit of item 9 or 10, wherein the verification model includes at least one rule for determining the expected sensor information based on the at least one other information.

[0096] 12. The control unit of item 11, wherein the at least one rule is determined from historical data related to the plant process.

[0097] 13. The control unit of any one of items 9 to 12, wherein the control unit is configured to switch in a safe control mode for controlling the plant process in response to the verification signal.

[0098] 14. The control unit of item 13, further configured to initiate a maintenance procedure, in particular a comparison/calibration procedure, for the sensor device, and to switch from the safe control mode to a normal control mode of the plant process, after receiving an indication that the maintenance procedure has been completed.

[0099] 15. A computer program comprising instructions which, when the program is executed by a control unit for controlling a plant process, in particular a water treatment process and/or a wastewater treatment process, the control unit being communicatively coupled to a sensor device associated with the plant process and sensing sensor information related to the plant process, cause the control unit to carry out the method of any one of items 1 to 8.