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Title:
METHOD AND SYSTEM FOR DEVIATION DETECTION IN SENSOR DATASETS
Document Type and Number:
WIPO Patent Application WO/2019/012029
Kind Code:
A1
Abstract:
A system, device and method of deviation detection in at least one sensor dataset associated with one or more sensors in a technical system are disclosed. The method includes generating a best fit model of the technical system based on a target sensor dataset. The method also includes predicting sensor dataset of the target sensor using the best fit model and non- target sensor data sets of non-target sensors and determining a deviation tolerance by determining a difference between the predicted sensor dataset and the target sensor dataset. Fur- ther, the method includes detecting deviation in actual sensor dataset of the target sensor when a data-point in the actual sensor dataset exceeds the deviation tolerance and detecting deviation in the at least one sensor dataset of the one or more sensors by detecting deviation in each of the non-target sensor datasets.

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Inventors:
RAMANATH VINAY (IN)
RIZVI KHALEELI ASMI (IN)
HEDGE GAURAV (IN)
Application Number:
PCT/EP2018/068902
Publication Date:
January 17, 2019
Filing Date:
July 12, 2018
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
SIEMENS AG (DE)
International Classes:
G05B23/02
Domestic Patent References:
WO2017116627A12017-07-06
Foreign References:
US20170102978A12017-04-13
US20160116378A12016-04-28
US20130204808A12013-08-08
US20110202488A12011-08-18
Other References:
None
Attorney, Agent or Firm:
PATENT ATTORNEYS WILHELM & BECK (DE)
Download PDF:
Claims:
Claims

1. A method of deviation detection in at least one sensor dataset associated with one or more sensors in a technical system, wherein the one or more sensors comprising a target sensor and non-target sensors, the method comprising:

receiving a target sensor dataset associated with the target sensor in time series;

generating a best fit model of the technical system based on the target sensor dataset;

predicting sensor dataset of the target sensor using the best fit model and non-target sensor datasets of non-target sensors ;

determining a deviation tolerance by determining a dif- ference between the predicted sensor dataset and the target sensor dataset;

detecting deviation in actual sensor dataset of the target sensor when a data-point in the actual sensor dataset exceeds the deviation tolerance; and

detecting deviation in the at least one sensor dataset of the one or more sensors by detecting deviation in each of the non-target sensor datasets.

2. The method as claimed in claim 1, wherein generating a best fit model of the technical system based on the target sensor dataset, comprises:

generating a system model from the target sensor dataset using a neural network model; and

generating the best fit model from the system model using projection pursuit regression.

3. The method as claimed in claim 1, predicting sensor dataset of the target sensor using the best fit model and non-target sensor datasets of non-target sensors, comprises:

determining dot products of non-target data-points in the non-target sensor dataset with weight of the best fit model.

4. The method as claimed in claim 1, wherein determining a deviation tolerance by determining a difference between the predicted sensor dataset and the target sensor dataset, com¬ prises :

determining the difference between predicted data-points in the predicted sensor dataset with target data-points in the target sensor dataset for each time instant; and

determining the deviation tolerance for each time instant based on the difference between the predicted data-points and the target data-points.

5. The method as claimed in claim 1, wherein detecting devia¬ tion in actual sensor dataset of the target sensor when a data- point in the actual sensor dataset exceeds the deviation tol- erance, comprises:

determining whether the data-point in the actual sensor dataset exceeds the deviation tolerance at for each time in¬ stant; and

detecting deviation in the actual sensor dataset when the data-point exceeds the deviation tolerance.

6. The method as claimed in claim 1, wherein detecting devia¬ tion in the at least one sensor dataset of the one or more sensors by detecting deviation in each of the non-target sensor datasets, comprises:

iteratively detecting deviation in each of the non-target sensor datasets by considering the non-target sensors as the target sensor; and

detecting deviation in the at least one sensor dataset by combining the deviations associated with each of the one or more sensors.

7. The method as claimed in claim 1, wherein the deviation detected in the target sensor dataset is a sensor deviation in the target sensor dataset or a prediction deviation in the predicted sensor dataset of the target sensor.

8. The method as claimed in claim 7, comprising: determining deviation in the non-target sensor datasets when the prediction deviation is determined, wherein the non- target sensor datasets and the target sensor dataset are ca¬ pable of converging to a deterministic function.

9. The method as claimed in claim 1, comprising:

determining a deviation periodicity in the at least one sensor dataset of the one or more sensors;

determining a sample period for each of the one or more sensors; and

predicting a subsequent deviation in the at least one sensor dataset based on the deviation periodicity and the sam¬ ple period. 10. he method as claimed in claim 9, wherein determining a deviation periodicity in the at least one sensor dataset of the one or more sensor, comprises:

determining a sensor threshold for each of the one or more sensors; and

determining the deviation periodicity in the at least one sensor dataset when the deviation tolerance at each time instant exceeds the sensor threshold.

11. The method as claimed in claim 9, further comprising:

determining a circular correlation plot for the at least one sensor dataset;

determining whether the deviation periodicity falls on a hill or a valley of the circular correlation plot; and

determining that the deviation periodicity is true when the deviation periodicity falls on the hill and false when the deviation periodicity falls on the valley.

12. The method as claimed in claim 1, further comprising:

determining a target sensitivity of the target sensor by performing a perturbation analysis on the target sensor dataset based on each of the non-target sensor datasets.

13. A deviation detection device for detecting deviation in at least one sensor dataset associated with one or more sensors in a technical system, the device comprising:

a receiver to receive the at least one sensor dataset in time series;

at least one processor; and

a memory communicatively coupled to the at least one pro¬ cessor, the memory comprising:

a model generator to generate a best fit model of the technical system based on the target sensor dataset; a prediction module to predict sensor dataset of the target sensor using the best fit model and non-target sensor datasets of non-target sensors;

a tolerance module to determine a deviation toler¬ ance by determining a difference between the predicted sensor dataset and the target sensor dataset;

a sensor deviation module to detect deviation in actual sensor dataset of the target sensor when a data- point in the actual sensor dataset exceeds the deviation tolerance; and

a system deviation module to detect deviation in the at least one sensor dataset of the one or more sensors by detecting deviation in each of the non-target sensor datasets.

14. he device as claimed in claim 13, wherein the model gen¬ erator comprises:

a system model generator to generate a system model from the target sensor dataset using a neural network model; and a best fit model generator to generate the best fit model from the system model using projection pursuit regression.

15. he device as claimed in claim 13, wherein the prediction module comprises:

a matrix module to determine dot products of non-target data-points in the non-target sensor dataset with weight of the best fit model.

16. he device as claimed in claim 13, wherein the tolerance module comprises:

a subtractor to determine the difference between pre¬ dicted data-points in the predicted sensor dataset with target data-points in the target sensor dataset for each time instant, wherein the deviation tolerance is determined for each time instant based on the difference between the predicted data- points and the target data-points. 17. he device as claimed in claim 13, wherein the sensor de¬ viation module comprises:

a comparator to determine whether the data-point in the actual sensor dataset exceeds the deviation tolerance at same time instant, wherein deviation in the actual sensor dataset is detected when the data-point exceeds the deviation toler¬ ance .

18. The device as claimed in claim 13, wherein the system de¬ viation module, comprises:

a deviation aggregator module to iteratively detect de¬ viation in each of the non-target sensor datasets by consid¬ ering the non-target sensors as the target sensor, wherein the deviation in the at least one sensor dataset is detected by combining the deviations associated with each of the one or more sensors.

19. The device as claimed in claim 13, wherein the memory com¬ prises :

a period generator to determine a deviation periodicity in the at least one sensor dataset of the one or more sensors; a sampling module to determine a sample period for each of the one or more sensors; and

a deviation predictor to predict a subsequent deviation in the at least one sensor dataset based on the deviation periodicity and the sample period.

20. The device as claimed in claim 19, wherein the deviation predictor comprises: a correlation module to determine a circular correlation plot for the at least one sensor dataset and determine whether the deviation periodicity falls on a hill or a valley of the circular correlation plot, wherein the deviation predictor de- termines that the deviation periodicity is true when the de¬ viation periodicity falls on the hill and false when the de¬ viation periodicity falls on the valley.

21. The device as claimed in claim 13, wherein the memory com- prises:

a sensitivity module to determine a target sensitivity of the target sensor by performing a perturbation analysis on the target sensor dataset based on each of the non-target sensor datasets .

22. A system for detecting deviation in at least one sensor dataset, the system comprising:

a server operable on a cloud computing platform;

a network interface communicatively coupled to the server; and

at least one technical system communicatively coupled to the server via the network interface,

wherein the server includes a deviation detection device for detecting deviation in at least one sensor dataset associated with at least one sensor in the at least one technical system, the device comprising:

a receiver to receive the at least one sensor dataset in time series;

at least one processor; and

a memory communicatively coupled to the at least one pro¬ cessor, the memory comprising:

a model generator to generate a best fit model of the technical system based on the target sensor dataset; a prediction module to predict sensor dataset of the target sensor using the best fit model and non-target sensor datasets of non-target sensors; a tolerance module to determine a deviation toler¬ ance by determining a difference between the predicted sensor dataset and the target sensor dataset;

a sensor deviation module to detect deviation in actual sensor dataset of the target sensor when a data- point in the actual sensor dataset exceeds the deviation tolerance; and

a system deviation module to detect deviation in the at least one sensor dataset of the one or more sensors by detecting deviation in each of the non-target sensor da- tasets .

Description:
Method and System for Deviation Detection in Sensor Datasets

[0001] This application claims the priority of the US patent application 15/647,847, filed July 12, 2017, which is incor- porated by reference herein, in the entirety and for all pur ¬ poses.

[0002] The present invention relates generally to automat ¬ ically determining error condition in sensors provided in a technical system.

[0003] Currently, almost every technical system is equipped with an operational data extraction system using a network of sensors placed across the system for diagnostic and prognostic applications. The sensors are required for online monitoring as well as offline analytics and therefore, sensor data is expected to be without anomalies or deviations from antici ¬ pated trends . [0004] Accordingly, it is important to identify sensor data-points in the sensor data whose anomalous nature cannot be accounted for by change in process of the technical system. In other words, the sensor data-points that are affected by sensor malfunctions and/or environmental interferences need to be identified. Further, in case of scarceness of the sensor data an additional challenge is that the identified sensor data-points may often be a false positive.

SUMMARY OF THE INVENTION

[0005] This summary is provided to introduce a selection of concepts in a simplified form that are further disclosed in the detailed description of the invention. This summary is not intended to identify key or essential inventive concepts of the claimed subject matter, nor is it intended for determining the scope of the claimed subject matter. [0006] In accordance with one aspect of the invention, there is provided a method of detecting deviation in one or more sensor dataset associated with multiple sensors in a technical system. The sensors can be classified as a target sensor and non-target sensors. The method includes receiving a target sensor dataset associated with the target sensor in time series and generating a best fit model of the technical system based on the target sensor dataset. Further, the method includes predicting sensor dataset of the target sensor using the best fit model and non-target sensor datasets of non-target sensors and determining a deviation tolerance by determining a difference between the predicted sensor dataset and the target sensor dataset. Furthermore, the method includes detecting deviation in actual sensor dataset of the target sensor when a data- point in the actual sensor dataset exceeds the deviation tol ¬ erance. The method also includes detecting deviation in the at least one sensor dataset of the one or more sensors by detect ¬ ing deviation in each of the non-target sensor datasets. [0007] Additionally, the method includes determining a de ¬ viation periodicity in the sensor dataset of the sensors and a sample period for each of the sensors. The deviation perio ¬ dicity and the sample period are used to predict a subsequent deviation in the sensor dataset. Further, the method includes determining a target sensitivity of the target sensor by per ¬ forming a perturbation analysis on the target sensor dataset based on each of the non-target sensor datasets.

[0008] In accordance with another aspect of the invention, there is provided a deviation detection device for detecting deviation in one or more sensor datasets of a plurality of sensors in a technical system. The device includes a receiver, one or more processors and a memory. The memory includes mod ¬ ules that are executed by the one or more processors. The modules include a model generator to generate a best fit model of the technical system based on the target sensor dataset. A prediction module to predict sensor dataset of the target sen ¬ sor using the best fit model and non-target sensor datasets of non-target sensors. A tolerance module to determine a devia ¬ tion tolerance by determining a difference between the pre ¬ dicted sensor dataset and the target sensor dataset. A sensor deviation detector to detect deviation in actual sensor da- taset of the target sensor when a data-point in the actual sensor dataset exceeds the deviation tolerance and

a system deviation detector to detect deviation in the one or more sensor datasets by detecting deviation in each of the non-target sensor datasets.

[0009] In accordance with yet another aspect of the inven ¬ tion there is provided a system for detecting deviation in one or more sensor datasets. The system includes a server operable on a cloud computing platform, a network interface communica- tively coupled to the server and one or more technical systems communicatively coupled to the server via the network inter ¬ face. The server includes a deviation detection device for detecting deviation in the sensor datasets associated with at least one sensor in the one or more technical systems.

[0010] The present invention is further described herein ¬ after with reference to illustrated embodiments shown in the accompanying drawings, in which: FIG 1A illustrates a model-fitting phase according to the pre ¬ sent invention;

FIG IB illustrates a deviation detection phase according to the present invention;

FIG 2 is a block diagram of a deviation detection device according to the present invention;

FIG 3 is a flowchart illustrating the method of detecting deviation in one or more sensor datasets, according to the present invention; FIG 4 is a block diagram of a system for detecting deviation in the one or more sensor datasets according to the present invention ; FIG 5 is a graph a deviation tolerance for a sensor dataset according to the present invention;

FIG 6 is a graph illustrating deviations detected in a com ¬ pressor outlet pressure dataset associated with a compressor outlet pressure sensor according to the present invention;

FIG 7A is a graph illustrating a comparison of actual sensor dataset and predicted sensor dataset associated with a rota ¬ tional speed sensor according to the present invention;

FIG 7B is a graph illustrating a comparison of actual sensor dataset and predicted sensor dataset associated with a combus ¬ tion flame sensor according to the present invention; FIG 7C is a graph illustrating a comparison of actual sensor dataset and predicted sensor dataset associated with a com ¬ pressor inlet pressure sensor according to the present invention; FIG 8 is a graph 800 illustrating a deviation periodicity in actual sensor dataset associated with exhaust temperature sen ¬ sor according to the present invention;

FIG 9 is a flowchart illustrating a method of predicting a subsequent deviation in actual sensor dataset associated with a target sensor according to the present invention; and

FIG 10 is a graph illustrating a target sensitivity of a target sensor with respect to non-target sensors according to the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS [0011] Various embodiments are described with reference to the drawings, wherein like reference numerals are used to refer to like elements throughout. In the following description, a large gas turbine has been considered as an example of a tech- nical system for the purpose of explanation. Further, numerous specific details are set forth in order to provide thorough understanding of one or more embodiments of the present inven ¬ tion. These examples must not be considered to limit the ap ¬ plication of the invention to large gas turbine and includes any technical system for sensor frozen period is automatically determined. It may be evident that such embodiments may be practiced without these specific details.

[0012] As used herein, the term "dataset'V'datasets" refers to data that a sensor records. The data recorded by the sensor is for a particular period of time. In the present embodiment, the sensor records the data in time series. The dataset com ¬ prises multiple data points, each representing a recording of the electronic device. As used herein, "sensor value" and "data point" are used interchangeably to mean a representation of one or more datums recorded for the at least one operative parameter associated with the technical system. The "at least one operation parameter" refers to one or more characteristics of the technical system. For example, if a gas turbine is the technical system, the at least one operation parameter includes combustion temperature, inlet pressure, exhaust pressure, etc.

[0013] Further, "target sensor" refers to one of a plurality of sensors that is used as input data or training data to determine a system model. The remaining sensors of the plural ¬ ity of sensors are referred to as "non-target sensors". The data-points generated by the target sensor are referred to as "target sensor dataset", which is used as training data to generate system model and best fit model. The data-points gen- erated by the non-target sensors are referred to as "non-target sensor dataset", which is used to predict sensor dataset of the target sensor. The term "actual sensor dataset" of the target sensor refers to data-points on which deviation is de ¬ tected. The "actual sensor dataset" and the "target sensor dataset" are both generated from the target sensor, however, the "target sensor dataset" is the training data used to build the system model while "actual sensor dataset" is the data with potential deviation. During the implementation of the present invention, a target sensor can be changed to a non- target sensor and vice versa. [0014] FIG 1A illustrates a model-fitting phase 100A ac ¬ cording to the present invention. The model fitting phase 100A is to train a neural network model on a training data 102 supplied. The training data 102 relates to a target sensor dataset associated with a target sensor. For example, consid- ering a gas turbine as the technical system, the target sensor can be an exhaust temperature sensor. The training data 102 used for the model fitting phase 100A is analyzed for anomalies using known anomaly detection methods involving adaptive whiskers and Local Outlier Probability estimation.

[0015] The training data 102 is used to generate a system model 104. The system model 104 is of one hidden layer with neurons adaptive to the training data 102. In an exemplary embodiment, the system model 104 is a list of an artificial neural network model, which is an object returned by a nnet function .

[0016] On the system model 104 a regression model 106 is applied. In an embodiment, a projection pursuit regression 106 determines projections that fit the system model 104 the best. After application of the regression model, a best fit model 108 is generated from the system model 104. Due to scarcity and inherent nature of randomness in the training data 102, anomalous data-points in the training data 102 tend to have minimal implications on the best fit model 108. The best fit model 108 is used in a deviation detection phase as detailed in FIG IB. [0017] FIG IB illustrates the deviation detection phase 100B according to the present invention. The best fit model 108 and non-target sensor datasets 110 are used to predict sensor dataset 112 of the target sensor. The predicted sensor dataset 112 is determined that based on a deterministic func ¬ tion between the non-target sensors and the target sensors as the sensors are related to each other by laws of physics. The predicted sensor dataset 112 is compared with the target sensor dataset to determine a deviation tolerance 114. Actual sensor dataset 116 associated with the target sensor is compared with the deviation tolerance 114 to detect sensor deviation 118 for the target sensor. Sensor deviation for all the sensors in the technical system is aggregated to determine system deviation for the technical system.

[0018] For example, the predicted sensor dataset 112 is generated for the target sensor for a period of January 1 to February 28 based on the non-target sensor datasets from Jan ¬ uary 1 to February 28. The predicted sensor dataset 112 is then compared with the target sensor dataset from January 1 to February 28 to determine the deviation tolerance 114. Further, the actual sensor dataset 116 of the target sensor for a period of March 1 to April 30 is compared with the deviation tolerance 114 to determine whether the actual sensor dataset 116 exceeds the deviation tolerance 114 at each time instant. When data- points in the actual sensor dataset 116 exceeds the deviation tolerance 114 at a given time instance, then the deviation is detected in the target sensor dataset. [0019] The model fitting phase and deviation detection phase is implemented via a deviation detection device. FIG 2 is a block diagram of a deviation detection device 200 according to the present invention. The deviation detection device 200 detects deviation in one or more sensor datasets associated with one or more sensors in a technical system. The technical system used for explaining is a large gas turbine. However, it is not limited to a large gas turbine and can include any system with multiple sensors. The deviation detection device 200 according to the present invention is installed on and accessible by a user device, for example, a personal computing device, a workstation, a client device, a network enabled com ¬ puting device, any other suitable computing equipment, and combinations of multiple pieces of computing equipment. The deviation detection device 200 disclosed herein is in operable communication with a database 202 over a communication network 205. [0020] The database 202 is, for example, a structured query language (SQL) data store or a not only SQL (NoSQL) data store. In an embodiment of the database 202 according to the present invention, the database 202 can also be a location on a file system directly accessible by the deviation detection device 200. In another embodiment of the database 202 according to the present invention, the database 202 is configured as cloud based database implemented in a cloud computing environment, where computing resources are delivered as a service over the network 205. As used herein, "cloud computing environment" refers to a processing environment comprising configurable computing physical and logical resources, for example, net ¬ works, servers, storage, applications, services, etc., and data distributed over the network 205, for example, the inter ¬ net. The cloud computing environment provides on-demand net- work access to a shared pool of the configurable computing physical and logical resources. The communication network 205 is, for example, a wired network, a wireless network, a com ¬ munication network, or a network formed from any combination of these networks.

[0021] In a preferred embodiment according to the present invention, the deviation detection device 200 is downloadable and usable on the user device. In another embodiment according to the present invention, the deviation detection device 200 is configured as a web based platform, for example, a website hosted on a server or a network of servers. In another embodiment according to the present invention, the deviation detec- tion device 200 is implemented in the cloud computing environ ¬ ment. The deviation detection device 200 is developed, for example, using Google App engine cloud infrastructure of Google Inc., Amazon Web Services® of Amazon Technologies, Inc., as disclosed hereinafter in FIG 4. In an embodiment, the deviation detection device 200 is configured as a cloud computing based platform implemented as a service for analyzing data.

[0022] The deviation detection device 200 disclosed herein comprises memory 206 and at least one processor 204 communi ¬ catively coupled to the memory 206. As used herein, "memory" refers to all computer readable media, for example, non-vola ¬ tile media, volatile media, and transmission media except for a transitory, propagating signal. The memory is configured to store computer program instructions defined by modules, for example, 210, 212, 218, 222, etc., of the deviation detection device 200. The processor 204 is configured to execute the defined computer program instructions in the modules. Further, the processor 204 is configured to execute the instructions in the memory 206 simultaneously. As illustrated in FIG 1, the deviation detection device 200 comprises a communication unit 208 including a receiver to receive the sensor dataset in time series and a display unit 160. Additionally, a user using the user device can access the deviation detection device 200 via a GUI (graphic user interface) . The GUI is, for example, an online web interface, a web based downloadable application interface, etc.

[0023] The modules executed by the processor 204 include a training data module 210, a model generator 212, a prediction module 218, a tolerance module 222, a sensor deviation module 226, a system deviation module 230, a period generator 234, a sampling module 236, a deviation predictor 238 and a sensitivity module 242.

[0024] The training data module 210 removes anomalies in a target sensor dataset associated with a target sensor known anomaly detection methods involving adaptive whiskers and Lo ¬ cal Outlier Probability estimation. The model generator 212 includes a system model generator 214 to generate a system model from the target sensor dataset. The model generator 212 also includes a best fit model generator 216 to generate a best fit model from the system model using projection pursuit regression .

[0025] The prediction module 218 predicts sensor dataset of the target sensor using the best fit model and the non-target sensor dataset. The prediction module 218 includes a matrix module 220 to determine dot-products of non target data-points, in the non-target sensor datasets, with weight of the best fit model. The dot-product dataset is the predicted sensor dataset of the target sensor.

[0026] The predicted sensor dataset is compared with the target sensor dataset to determine a deviation tolerance. This is performed using the tolerance module 222 that includes a subtractor 224. The subtractor 224 determines the difference between predicted data-points in the predicted sensor dataset with target data-points in the target sensor dataset for each time instant. Therefore, the deviation tolerance is a dataset of the difference between the predicted data-points and the target data-points determined for each time instant.

[0027] The deviation tolerance is used to determine devia ¬ tion in actual dataset of the target sensor by the sensor deviation module 226. The sensor deviation module 226 includes a comparator 228 to determine whether the data-point in the actual sensor dataset exceeds the deviation tolerance at a given time instant. When the data-point exceeds the deviation tolerance, deviation in the actual sensor dataset is detected. [0028] Deviation of in the non-target sensor datasets is determined by considering each of the non-target sensors as the target sensor and iteratively executing the instructions in the modules 210 to 226. The system deviation module 230 includes a deviation aggregator module 232 that iteratively detects deviation in each of the non-target sensor datasets by considering the non-target sensors as the target sensor. The deviation aggregator module 232 generates a union of all the deviations from the sensors in the technical system to give an aggregated report of all anomalies present in the one or more datasets associated with the operation of the technical sys ¬ tem. FIGs 5, 6, 7A, 7B and 7C illustrate the operation the deviation detection device 200.

[0029] The deviation detection device 200 can also predict a subsequent deviation that could occur in the sensor dataset. To predict the subsequent deviation the device 200 includes the period generator 234, sampling module 236 and the deviation predictor 238. The period generator 234 determines a deviation periodicity in the sensor datasets of the one or more sensors in the technical system. The sampling module 236 determines a sample period for each of the one or more sensors. The devia ¬ tion predictor 238 includes a correlation module 240 to deter- mine a circular correlation plot for the sensor dataset and determine whether the deviation periodicity falls on a hill or a valley of the circular correlation plot. If the deviation periodicity falls on the hill the deviation periodicity is true and if the deviation periodicity falls on the valley the deviation periodicity is false. The method used to predict the subsequent deviation is further elaborated in FIG 9.

[0030] The deviation detection device 200 can also determine the sensitivity of the target sensor with respect to changes in the non-target sensor. The sensitivity module 242 performs a perturbation analysis on the target sensor dataset based on each of the non-target sensor datasets to determine a target sensitivity. This can be iteratively performed for all the sensors in the technical system to understand the sensor sensitivity for each of the sensors. This is further elaborated in the explanation to FIG 10. [0031] As indicated in the aforementioned paragraphs the deviation detection device 200 performs three main functions. They include

a. Neural Network based regression for detecting deviations of the actual sensor dataset from the predicted sensor dataset. b. Sensitivity analysis of the sensors used to develop the system model of the technical system for variable significance and quantifying sensitivities of sensor output.

c. Periodicity estimation of the deviations to predict the next occurrence of the subsequent deviation.

The method to perform the three main functions is provided as a flowchart in FIG 3.

[0032] FIG 3 is a flowchart 300 illustrating the method of detecting deviation in one or more sensor datasets, according to the present invention. The method beings at step 302 with receiving a target sensor dataset associated with a target sensor in a technical system. The technical system includes multiple sensors that generate the one or more sensor datasets. The target sensor is one of the multiple sensors in the tech ¬ nical system. The target sensor dataset is used as training data with which a system model for the technical system is built . [0033] At step 304 a system model from the target sensor dataset is generated using a neural network model. In an ex ¬ emplary embodiment, the neural network model is an Artificial Neural Network (ANN) . At step 306 a best fit model is generated from the system model using projection pursuit regression. The projection pursuit regression includes an additive model that is fit to the data. The non linear functions need to be assumed in advance while the weights are determined when the best fit model is determined. In an exemplary embodiment, the best fit model is implemented with the ANN of a single hidden layer. The ANN minimizes a residual sum-of-squares (RSS) over the target sensor dataset to find the best fit model, with a back- propagation algorithm estimating the gradients for optimization. [0034] At step 308 the step of predicting sensor dataset of the target sensor using the best fit model and non-target sensor datasets of non-target sensors is performed. Since the best fit model is generated using the target sensor dataset, the non-target sensor dataset is used to predict the values of the target sensor using the best fit model. This is possible considering that the sensors in the technical system at related by laws of physics.

[0035] At step 310 a deviation tolerance is determined by determining a difference between the predicted sensor dataset and the target sensor dataset. In an embodiment, the target sensor dataset is divided into a target training dataset and a test dataset. The target training dataset is used to generate the system model and the best fit model. The predicted sensor dataset is generated based on the target training dataset. The accuracy of the predicted sensor dataset is then determined by the difference between the test dataset and the predicted sen- sor dataset. This difference at each time instant is referred to as the deviation tolerance.

[0036] At step 312 deviation in actual sensor dataset of the target sensor is detected when a data-point in the actual sensor dataset exceeds the deviation tolerance. Data-points of the actual sensor dataset are analyzed to determine whether they exceed the deviation tolerance for the given time instant. If the actual data-point in the actual sensor dataset exceeds the deviation tolerance, deviation is detected. The deviation detected in the target sensor dataset can be a sensor deviation in the target sensor dataset or a prediction deviation in the predicted sensor dataset of the target sensor. In other words, the deviation is detected based on the deviation tolerance, which is in turn based on the non-target sensor dataset there is a possibility of deviation in the non-target sensor dataset. Accordingly, the deviation in the actual sensor dataset can be attributed to either deviation in the actual sensor dataset or deviation in the non-target sensor dataset. This is further explained in FIGs 7A, 7B and 7C.

[0037] At step 314 deviations in all the sensors in the technical system is determined by iteratively performing the above steps. Each of the non-target sensors are considered as the target sensor and the best fit model for each sensor is generated. From the best fit model the sensor values are pre ¬ dicted and deviation in each non-target sensor dataset is de- termined.

[0038] At step 316 the deviation in all the sensor datasets is aggregated to determine a true list of all anomalies present in the sensor dataset associated with the sensors in the tech- nical system. Accordingly, at step 316 deviations in the sensor dataset is determined by combining the deviations associated with each of the one or more sensors.

[0039] The above method can be divided into two phases as indicated in FIGs 1A and IB, i.e. the model fitting phase and the deviation detection phase. The best fit model generated at the end of the model fitting phase can also be used for sensor sensitivity analysis. Accordingly, at step 318 a target sen ¬ sitivity of the target sensor is determined by performing a perturbation analysis on the target sensor dataset based on each of the non-target sensor datasets. The perturbation anal ¬ ysis allows study of changes in characteristics of a function when small perturbations are seen in the function' s parame ¬ ters . In other words, the perturbation analysis refers to how a neural network output is influenced by its input and/or weight perturbations i.e. how the best fit model varies based on the changes in the non-target sensor datasets. In an embod ¬ iment, the perturbation analysis involves measurement of the sensitivities based on the evaluation of the Taylor Series Expansion (TSE) of the cost function which is the Residual Sum—of—Squares (RSS) , with appropriate approximations that are necessary for the application. In an exemplary embodiment, approximation till the first derivative in the TSE is per ¬ formed. This is explained further with the example of exhaust temperature sensor in FIG 10. [0040] The method allows for further analysis of the devi ¬ ation tolerance at step 320. Sensor threshold for each of the sensors in the technical system is determined or known. The sensor threshold is compared with the deviation tolerance to determine a deviation periodicity. If the deviation tolerance is within the sensor threshold it is substitute by zero and accordingly, the deviation periodicity is determined at each instant when the deviation tolerance exceeds the sensor thresh ¬ old. At step 322 a sampling period of the sensors is deter ¬ mined. In an embodiment the sampling period of the sensors is already known. At step 324 a subsequent deviation in the one or more sensor datasets is determined based on the deviation periodicity and the sample period. This is further elaborated by the flowchart in FIG 9. [0041] FIG 4 is a block diagram of a system 400 for detecting deviation in the one or more sensor datasets according to the present invention. The system 400 includes a server 404 comprising the deviation detection device 200. The system 400 also comprises a network interface 405 communicatively coupled to the server 404 and technical systems 410A-410C communica ¬ tively coupled to the server 404 via the network interface 405. The server 404 includes the deviation detection device 200 for detecting deviation detection in sensor dataset associated with one or more sensor associated with the technical systems 410A-410C. The technical systems 410A-410C are located in a remote location while the server 405 is located on a cloud server for example, using Google App engine cloud infrastruc ¬ ture of Google Inc., Amazon Web Services® of Amazon Technolo ¬ gies, Inc., the Amazon elastic compute cloud EC2® web service of Amazon Technologies, Inc., the Google® Cloud platform of Google Inc., the Microsoft® Cloud platform of Microsoft Cor ¬ poration, etc. The technical systems 410A, 410B and 410C in ¬ clude sensors 420A, 420B and 420C, respectively. The sensors 420A, 420B and 420C are used to generate one or more sensor datasets including sensor values corresponding to one or more operation parameters associated with the technical systems 410A, 410B and 410C.

[ 0042 ] In case the server 405 is a cloud server, a system model and a best fit model can be fit on historic data asso ¬ ciated with the operation of the technical systems 410A-410C. The historic data is saved in a database 402, which can be a cloud based database. The deviation detection is performed in real-time by receiving sensor datasets from the sensors 420A- 420C. The deviation detection performed iteratively on the sensors 420A-420C all at once. [ 0043] FIG 5 is a graph 500 a deviation tolerance for a sensor dataset. According to the graph 500 on the x-axis 502 is difference between target sensor dataset and predicted sen ¬ sor dataset for a target sensor. As explained in FIG 2, the target sensor dataset is used to generate the best fit model and the predicted sensor dataset is generated from the best fit model and non-target sensor datasets. The difference is also referred to as the deviation tolerance.

[ 0044 ] The y-axis 504 indicates the number of times the deviation tolerance is repeated. As shown in the graph 500, the difference 0.2 is repeated most number of times as indi ¬ cated at point 510. The graph 500 also indicates highest de ¬ viation tolerance 515 at 0.4. The highest deviation tolerance can be used as a threshold for to determine deviation. In other words, when data-points in actual sensor dataset of the target sensor exceed the threshold deviation is detected.

[ 0045] FIG 6 is a graph 600 illustrating deviations detected in a compressor outlet pressure dataset associated with a com- pressor outlet pressure sensor. For the purpose of graph 600, the technical system is a gas turbine. The solid line 606 indicates actual sensor dataset of the compressor outlet pres- sure sensor while the dashed line 608 indicates predicted sen ¬ sor dataset of the compressor outlet pressure sensor. The x- axis 602 indicates time instant and the y-axis 604 indicates values of data-points in the actual sensor dataset 606 and the predicted sensor dataset 608. The spikes 610 in the actual sensor dataset 606 are deviations from the predicted sensor dataset 608. Accordingly, the spikes 610 are the deviations detected in the actual sensor dataset of the compressor outlet pressure sensor.

[0046] When deviation is detected in sensor datasets it can be of two types, i.e. deviation in the actual sensor dataset of the target sensor or deviation in the predicted sensor dataset of the target sensor. FIGs 7A-7C illustrate the two types of deviations and the relationship between sensors in the technical system of a gas turbine.

[0047] FIG 7A is a graph illustrating a comparison of actual sensor dataset and predicted sensor dataset associated with a rotational speed sensor. The x-axis 702 indicates the time and the y axis 704 indicates values of actual sensor dataset 706 and predicted sensor dataset 708 of the rotational speed sen ¬ sor. As shown in the graph, there is a spike in the predicted sensor dataset 708. This indicates a deviation is the predicted sensor dataset. Deviation in the predicted sensor dataset 708 relates to deviation in sensor datasets associated with sen ¬ sors apart from the rotational speed sensor as illustrated in FIG 7B. [0048] FIG 7B is a graph illustrating a comparison of actual sensor dataset and predicted sensor dataset associated with a combustion flame sensor. The x-axis 712 indicates the time and the y-axis 714 indicates the values of actual sensor dataset 716 and predicted sensor dataset 718 of the combustion flame sensor. The spike in actual sensor dataset 716 at time instant 20000 can be associated to the spike in the predicted sensor dataset 708 in FIG 7A. Apart from the spike in the actual sensor dataset 716, spike 710 can be seen in the predicted sensor dataset 718. The spike 710 can be associated with a deviation in sensor dataset apart from the combustion flame sensor as indicated in FIG 7C. [0049] FIG 7C is a graph illustrating a comparison of actual sensor dataset and predicted sensor dataset associated with a compressor inlet pressure sensor. The x-axis 722 indicates the time and the y-axis 724 indicates values of actual sensor dataset 726 and predicted sensor dataset 728 of the compressor inlet pressure sensor. The spike in the actual sensor dataset 726 is comparable to the spike 710 in FIG 7B. Therefore, the method of forming individual models on each sensor and itera- tively using deviation detection for each sensor increases the robustness of our approach. If a deviation is missed by one models, it is captured by another model from the set of devel ¬ oped models.

[0050] FIG 8 is a graph 800 illustrating a deviation periodicity in actual sensor dataset associated with exhaust tem- perature sensor. Deviation tolerance of predicted sensor da ¬ taset of the exhaust temperature sensor is determined. The deviation tolerance is compared with sensor threshold associ ¬ ated with the exhaust temperature sensor. The sensor threshold can be determined based on laws of physics and from manufac- turing specification of the exhaust temperature sensor. The x- axis 802 indicates the time and the y axis 804 indicates the deviation tolerance that exceeds the sensor threshold. The deviation periodicity 810 indicates periodic deviations occur ¬ ring in the actual sensor dataset of the exhaust temperature sensor. The deviation periodicity 810 can be used to predict a subsequent deviation in the data generated by the exhaust temperature sensor. This is explained further by the flowchart in FIG 9. [0051] FIG 9 is a flowchart illustrating a method 900 of predicting a subsequent deviation in actual sensor dataset associated with a target sensor. The actual sensor dataset 902 is received and deviation periodicity 906 is determined from deviation tolerance and sensor threshold 904 associated with the target sensor. In an embodiment, the deviation periodicity 906 is determined based on the sensor threshold 904 determined from Power Spectral Densities (PSDs) of its permuted signals. The deviation periodicity 906 is applied on an Auto-Correla ¬ tion Function (ACF) 908. At 910, curvature around the deviation periodicity falling on the ACF 908 is used to determine the subsequent deviation. If deviation periodicity 906a falls on a hill 912 of the ACF 908, then the deviation periodicity 906a is refined at 914 to determine the subsequent deviation 916. If deviation periodicity 906b falls on a valley 918 of ACF 908, then the deviation periodicity 906b is dismissed as a false alarm 920. [0052] FIG 10 is a graph 1000 illustrating a target sensi ¬ tivity of a target sensor with respect to non-target sensors. For the purpose of the graph 1000, the target sensor is exhaust temperature sensor of a gas turbine. The non-target sensors include compressor inlet pressure sensor 1010, inlet guide vanes sensor 1012, inlet filter differential pressure sensor 1014, feed pressure sensor 1016, rotational speed sensor 1018, compressor outlet temperature sensor 1020, outlet temperature sensor 1022, compressor inlet temperature sensor 1024 and compressor outlet pressure sensor 1026.

[0053] The x-axis 1002 indicates the non-target sensors 1010-1026 and the y-axis 1004 indicate the target sensitivity of the exhaust temperature sensor with respect to the non- target sensors 1010-1026. As shown in the graph the exhaust temperature sensor is most sensitive to the changes in the compressor outlet pressure sensor 1026, followed by the inlet filter differential pressure 1014 and the compressor inlet pressure sensor 1024. [0054] The graph 1000 is especially beneficial in technical systems such as the gas turbines as multiple sensors in the order of hundred may connected. The designing of such technical systems can be simplified by quantifying the relative im ¬ portance of each sensor to a target sensor.

[0055] It will be readily apparent that the various methods, algorithms, and modules disclosed herein may be implemented on computer readable media appropriately programmed for computing devices. The modules that implement the methods and algorithms disclosed herein may be stored and transmitted using a variety of media, for example, the computer readable media in a number of manners. In an embodiment, hard-wired circuitry or custom hardware may be used in place of, or in combination with, software instructions for implementation of the processes of various embodiments. Therefore, the embodiments are not lim ¬ ited to any specific combination of hardware and software. In general, the modules comprising computer executable instruc ¬ tions may be implemented in any programming language. The mod ¬ ules may be stored on or in one or more mediums as object code. Various aspects of the method and system disclosed herein may be implemented in a non-programmed environment comprising doc- uments created, for example, in a hypertext markup language (HTML) , an extensible markup language (XML) , or other format that render aspects of a graphical user interface (GUI) or perform other functions, when viewed in a visual area or a window of a browser program. Various aspects of the method and system disclosed herein may be implemented as programmed ele ¬ ments, or non-programmed elements, or any suitable combination thereof .

[0056] Where databases comprising data points are de- scribed, it will be understood by one of ordinary skill in the art that (i) alternative database structures to those described may be readily employed, and (ii) other memory structures be ¬ sides databases may be readily employed. Any illustrations or descriptions of any sample databases disclosed herein are il- lustrative arrangements for stored representations of infor ¬ mation. Any number of other arrangements may be employed be ¬ sides those suggested by tables illustrated in the drawings or elsewhere. Similarly, any illustrated entries of the databases represent exemplary information only; one of ordinary skill in the art will understand that the number and content of the entries can be different from those disclosed herein. Further, despite any depiction of the databases as tables, other formats including relational databases, object-based models, and/or distributed databases may be used to store and manipulate the data types disclosed herein. Likewise, object methods or be ¬ haviors of a database can be used to implement various pro ¬ cesses such as those disclosed herein. In addition, the data- bases may, in a known manner, be stored locally or remotely from a device that accesses data in such a database. In embod ¬ iments where there are multiple databases in the system, the databases may be integrated to communicate with each other for enabling simultaneous updates of data linked across the data- bases, when there are any updates to the data in one of the databases .

[0057] The present invention can be configured to work in a network environment comprising one or more computers that are in communication with one or more devices via a network. The computers may communicate with the devices directly or indirectly, via a wired medium or a wireless medium such as the Internet, a local area network (LAN) , a wide area network (WAN) or the Ethernet, a token ring, or via any appropriate communications mediums or combination of communications medi ¬ ums. Each of the devices comprises processors, some examples of which are disclosed above, that are adapted to communicate with the computers. In an embodiment, each of the computers is equipped with a network communication device, for example, a network interface card, a modem, or other network connection device suitable for connecting to a network. Each of the computers and the devices executes an operating system, some ex ¬ amples of which are disclosed above. While the operating system may differ depending on the type of computer, the operating system will continue to provide the appropriate communications protocols to establish communication links with the network. Any number and type of machines may be in communication with the computers . [0058] The present invention is not limited to a particular computer system platform, processor, operating system, or network. One or more aspects of the present invention may be distributed among one or more computer systems, for example, servers configured to provide one or more services to one or more client computers, or to perform a complete task in a distributed system. For example, one or more aspects of the present invention may be performed on a client-server system that comprises components distributed among one or more server systems that perform multiple functions according to various embodiments. These components comprise, for example, executa ¬ ble, intermediate, or interpreted code, which communicate over a network using a communication protocol. The present inven- tion is not limited to be executable on any particular system or group of systems, and is not limited to any particular distributed architecture, network, or communication protocol.

[0059] The foregoing examples have been provided merely for the purpose of explanation and are in no way to be construed as limiting of the present invention disclosed herein. While the invention has been described with reference to various embodiments, it is understood that the words, which have been used herein, are words of description and illustration, rather than words of limitation. Further, although the invention has been described herein with reference to particular means, ma ¬ terials, and embodiments, the invention is not intended to be limited to the particulars disclosed herein; rather, the in ¬ vention extends to all functionally equivalent structures, methods and uses, such as are within the scope of the appended claims. Those skilled in the art, having the benefit of the teachings of this specification, may affect numerous modifi ¬ cations thereto and changes may be made without departing from the scope and spirit of the invention in its aspects.