Patent Publication Number: US-2016239755-A1

Title: Correlation and annotation of time series data sequences to extracted or existing discrete data

Description:
FIELD OF THE INVENTION 
     The present disclosure relates generally to a system and method for predicting events. More particularly, the present disclosure relates to a system and method for predicting events by associating time series data with other, non-time series, data. 
     BACKGROUND OF THE INVENTION 
     Advances in technology have enabled the development of increasingly complex industrial systems. Further, equipment maintenance within these systems has also evolved over the years from purely corrective maintenance, which reacts to equipment breakdowns, to predictive analysis, which detects early signs of system anomalies. Anomaly detection is an important step in equipment monitoring, fault diagnostics, and system prognostics. All these steps are closely related. Fault diagnostics refer to root cause analysis of a detected fault or an observed change in operational state in a piece of equipment. System prognostics refer to the prediction of impending faults or operational state changes, or the estimation of remaining useful life for a piece of equipment. 
     Thus, anomaly detection generally involves monitoring changes to the system state to detect equipment malfunction or faulty behavior. Early detection of anomalies allows for timely maintenance actions to be taken before a fault grows in severity, causing secondary damage and equipment downtime. Detecting abnormal conditions is an important first step in both system diagnosis and prognosis, because abnormal behavioral characteristics are often the first sign of a potential future equipment failure. One common approach to anomaly detection is a data-driven approach that utilizes time series data to detect equipment behavior changes tracked in sensor measurements taken during the normal operation of the equipment. 
     Each of the system components generally are monitored by a plurality of sensors that provide real-time samples of key metrics such as temperature, pressure, and vibration, which individually or in aggregate represent one or more performance characteristics. The performance characteristics may be used to measure the degradation of the components of the system over time. For example, these performance characteristics may include estimates or measurements of physical conditions, operational efficiency, projected remaining operational lifetime, or time to failure of the system or a component thereof. 
     Through the use of the sensors, the system monitors numerous parameters and collects in real time vast amounts of data for analysis. In addition to time series data, the system monitors the components to collect, for example, discrete alarm data, which can detect the occurrence of a particular event of interest. The events may happen infrequently, may be monitored over a short period of time, or may be monitored on scheduled regular intervals such as daily or weekly. 
     An event may occur when, e.g., an operating parameter falls outside of a determined threshold, which may trigger an alarm. For example, an alarm event may relate to a process alarm, an equipment alarm, a safety alarm, or a shutdown alarm. The process alarm assists with the detection of changes to the efficiency of a process. An equipment alarm detects problems with equipment. A safety alarm alerts a system operator to a condition that may be potentially dangerous or damaging to the system or its surroundings. Shutdown alarm informs the system operator that an automatic shutdown event has been reached and a shutdown of the equipment or system may have been initiated. 
     When an event occurs during the operation of the system, the parameters of the time series data related to the event are often analyzed in order to determine a correlation between the event and the time series data to enable the development of prognostics rules for future use. Such an analysis of the time series data for the purpose of anomaly detection is particularly important for understanding the interrelationship between the performance characteristics of the equipment or system during the time series which can be used to predict the occurrence of a future event. 
     Thus, there is a need for a predictive system that has the capability to identify new patterns within time series data with the further capability to associate the newly identified patterns within the time series data with various other types of data, such as alarm and event data. There is also a need for a system that quantifies the inter-relationship between the time series data and the event data to detect or predict future events. 
     SUMMARY OF THE INVENTION 
     In at least one aspect, the present disclosure provides a system for predicting events by associating time series data with other types of data. This system can include a processing unit configured to receive a data stream including time series data transmitted from a sensor configured to measure an operating parameter of a component being monitored. The processing unit analyzes the data stream to identify a sequence of interest in the time series data. The processing unit extracts the identified sequence of interest from the time series data as an extracted event. The processing unit quantifies the relationship between the time series data of the extracted event and the known event by calculating a confidence level to denote a statistical probability of occurrence of the event by comparing data patterns of the extracted event with data of the template pattern of the known event. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  illustrates an exemplary industrial system for use with the predictive system according to the present disclosure, in this case a gas turbine engine; 
         FIG. 1B  illustrates a schematic diagram of the gas turbine engine of  FIG. 1A  and depicts an exemplary embodiment of a predictive system including the gas turbine engine; 
         FIG. 2  illustrates a process flow diagram of a method for predicting events by associating time series data with various types of data in accordance with the present disclosure; 
         FIG. 3  illustrates a process flow diagram of a method for predicting events by associating time series data with various types of data in accordance with the present disclosure; and 
         FIG. 4  illustrates an exemplary computing system. 
     
    
    
     The present disclosure may take form in various components and arrangements of components, and in various process operations and arrangements of process operations. The present disclosure is illustrated in the accompanying drawings, throughout which, like reference numerals may indicate corresponding or similar parts in the various figures. The drawings are only for purposes of illustrating preferred embodiments and are not to be construed as limiting the disclosure. Given the following enabling description of the drawings, the novel aspects of the present disclosure should become evident to a person of ordinary skill in the art. 
     DETAILED DESCRIPTION 
     The following detailed description is merely exemplary in nature and is not intended to limit the applications and uses disclosed herein. Further, there is no intention to be bound by any theory presented in the preceding background or summary or the following detailed description. 
     In at least one embodiment, the system and method predicts events by associating time series data with other types of data. The system and method can include a processing unit configured to receive a data stream including time series data transmitted from a sensor configured to measure an operating parameter of a component being monitored. The processing unit analyzes the data stream to identify a sequence of interest in the time series data. The processing unit extracts the identified sequence of interest from the time series data as an extracted event. The processing unit quantifies the relationship between the time series data of the extracted event and the known event by calculating a confidence level to denote a statistical probability of occurrence of the event by comparing data patterns of the extracted event with data of the template pattern of the known event. 
       FIGS. 1A-1B  illustrate an exemplary embodiment that relates to a system and method for predicting events of a component, by associating time series data with various types of data, for example, event and alarm data and quantifying the inter-relationships between the data to enable real-time assessment of the time series data to detect or predict future events. 
     In a particular embodiment, and as will be described in greater detail below, the industrial system being monitored by a prediction system is a gas turbine engine. It should be noted that the gas turbine engine component in the prediction system describes an exemplary embodiment. Those skilled in the art will appreciate that the disclosed prediction system is not limited to a gas turbine engine in particular, and may be applied, in general, to a variety of systems or devices, such as, for example, locomotives, aircraft engines, automobiles, turbines, computers, appliances, spectroscopy systems, nuclear accelerators, medical equipment, biological cooling facilities, manufacturing lines, and power transmission systems, to name but a few. 
       FIGS. 1A-1B  illustrate the prediction system  100  for a gas turbine engine  102 , which is used to power, for example, a helicopter (not shown). Gas turbine engine  102  comprises an air intake  104 , a compressor  106 , a combustion chamber  108 , a gas generator turbine  110 , a power turbine  112 , and an exhaust  114 . 
     At the air intake  104 , air is suctioned through the inlet section by the compressor  106 . Air filtration occurs in the inlet section via particle separation. Air is then compressed by the compressor  106  where the air is used primarily for power production and cooling purposes. Fuel and compressed air is burned in the combustion chamber  108  producing gas pressure, which is directed to the different turbine sections  110 ,  112 . 
     Gas pressure from the combustion chamber  108  is blown across the gas generator turbine rotors  110  to power the engine and blown across the power turbine rotors  112  to power the helicopter. The two turbines  110 ,  112  operate on independent output shafts  116 ,  117 . Hot gases exit the engine exhaust  114  to produce a high velocity jet. 
     One or more sensors  118  are attached at predetermined locations such as  1 ,  2 ,  3 ,  4 , and  5  to the gas turbine engine  102 . Sensors  118  may be integrated into a housing of the gas turbine  102  or may be removably attached to the housing. Each sensor  118  can generate sensor data that is used by the prediction system  100 . In general, a “sensor” is a device that measures a physical quantity and converts it into a signal which earl be read by an observer or by an instrument. In general, sensors can be used to sense light, motion, temperature, magnetic fields, gravity, humidity, vibration, pressure, electrical fields, sound, and other physical aspects of an environment. 
     Non-limiting examples of sensors can include acoustic sensors, vibration sensors, vehicle sensors, chemical sensors/detectors, electric current sensors, electric potential sensors, magnetic sensors, radio frequency sensors, environmental sensors, fluid flow sensors, position, angle, displacement, distance, speed, acceleration sensors, optical, light, imaging sensors, pressure sensors and gauges, strain gauges, torque sensors, force sensors piezoelectric sensors, density sensors, level sensors, thermal, heat, temperature sensors, proximity/presence sensors, etc. 
     Sensors  118  provide sensor data to a monitoring device  120 , The monitoring device  120  measures characteristics of the gas turbine engine  102 , and quantifies these characteristics into data that can be analyzed by a processor  132 . For example, the monitoring device may measure power, energy, volume per minute, volume, temperature, pressure, flow rate, or other characteristics of the gas turbine engine. The monitoring device may be a suitable monitoring device such as an intelligent electronic device (IED). As used herein, the monitoring device refers to any system element or apparatus with the ability to sample, collect, or measure one or more operational characteristics or parameters of the predictive system. 
     The monitoring device  120  includes a controller  122 , firmware  124 , memory  126 , and a communication interface  130 , The firmware  124  includes machine instructions for directing the controller  122  to carry out operations required for the monitoring device. Memory  126  is used by the controller  122  to store electrical parameter data measured by the monitoring device  120 . 
     Instructions from the processor  132  are received by the monitoring device  120  via the communications interface  130 . In various embodiments, the instructions may include, for example, instructions that direct the controller  122  to mark the cycle count, to begin storing electrical parameter data, or to transmit to the processor  132  electrical parameter data stored in the memory  126 . The monitoring device  120  is communicatively coupled to the processor  132 . One or more sensors  118  may also be communicatively coupled to the processor  132 . 
     The prediction system  100  gathers data from the monitoring device  120  and other sensors  118  for predicting events by associating time series data with various types of data, such as alarm and event data and quantifying the inter-relationships between the data to enable real-time assessment of the time series data to detect or predict future events. The prediction system outputs data and runs a process algorithm according to aspects disclosed herein. The process algorithm includes instructions for associating time series data with other data, such as event and alarm data. 
     The prediction system  100  provides a process to identify correlations between time series data (e.g., sensor readings) and relational/non-relational data (e.g., alarms and events). In an embodiment, this process may include identifying new patterns across multiple time series variables that lead to an alarm or event. In another embodiment, the process may include detecting the existence of predefined patterns in a time series data stream in order to detect or predict a new event. 
     At least two principal approaches to associating the time series data with the alarm and event data to predict future events are disclosed herein: a data extraction approach and a data correlation approach. In the data extraction approach, time series data can be analyzed to extract sequences matching known patterns of interest. A weighting value can be assigned to indicate how well the sequence matches the predefined pattern. 
     For example, a startup sequence may be identified in gas turbine sensor data, utilizing pattern matching against a template pattern. The newly identified startup event can then be stored, along with a value indicating a confidence level that the sequence was correctly identified as a startup event based on how closely the time series data matched the predefined pattern. 
     A known stored pattern that corresponds to a startup of the gas turbine can be compared to the time series data gathered from different sensors. Based on the analysis, the system can determine, for example, that there is an 80% likelihood of the occurrence of a startup event based on how closely the current time series sensor data matches on the predefined pattern. 
     In the data correlation approach, sequences of time series data may be correlated to a separately stored, existing event or other discrete data to determine whether any correlation exists between the new time series sequence and stored sequences of known events. The correlation values indicate the strength of the relationship between the time series sequence and the existing stored data. Historical time series data may be mined to identify new patterns that have high correlation to events of interest. 
     For example, it may be determined that a particular pattern or sequence in gas turbine time series data acts as a leading indicator to a failure event that follows shortly thereafter. The correlation values within the newly defined pattern indicate the likelihood that the sequence will be followed by the failure event. The extracted events and correlation values are then applied to real-time data streams to identify potentially important sequences, in order to detect specific events or even predict future events before they occur. 
     In  FIGS. 2 and 3 , the prediction system identifies and quantifies relationships between time series and alarm or event data to predict future events. Types of data other than event or alarm data may be used by the prediction system  100  to predict future events. Those skilled in the art would recognize that the prediction system can be used to identify and quantify relationships between time series data and a variety of data types, such as continuous data, discrete data and random data. 
     In the data extraction approach illustrated in the exemplary embodiment of  FIG. 2 , a process algorithm receives a stream of data transmitted from the sensors  118  and monitoring device  120 . For example, temperature and pressure sensors  118 , collectively indicated generally by reference numeral  118 , are located on the gas turbine engine  102 . Of course, there may be any number of sensors located throughout the gas turbine engine  102  for monitoring any number of conditions. 
     The various sensors  118  throughout the system may provide operational data regarding the gas turbine engine  102  to the monitoring device  120 . Moreover, the controller  122  may also provide data to the monitoring device  120 . By way of example, the monitoring device  120  may receive and process data regarding the temperature within the engine, the pressure within the engine, the heat rate, exhaust flow, exhaust temperature, and pressure rate or a host of any other operating conditions regarding the engine  102 . 
     In block  200 , the process algorithm analyzes the incoming data stream to identify sequences of interest having predictive value. For example, the process algorithms may perform pattern matching to known template patterns to identify the sequences of interest. In block  210 , one or more pattern matching techniques may be employed, potentially including regression, neural networks, decision trees, Bayesian classifiers, Support Vector Machines, clustering, rule induction, nearest neighbor, simple aggregate approximation or cross-correlation. Those skilled in the art would recognize that other pattern matching algorithms may be used, as well. 
     Once a sequence is identified that matches a template, in block  220 , the process algorithm extracts and stores the identified sequence in a device as a newly “extracted” event for further analysis. The extracted event indicates that a certain event has been detected or is predicted to occur. Because the patterns involve multiple metrics across an interval of time, in various embodiments, the sequences of interest can be specified by a beginning time and ending time for the extracted event before storage. 
     In block  230 , the process algorithm calculates a confidence level to denote a probability that the event of interest occurred. The confidence level of the probability of occurrence is based on how closely the sequence matches the known template. To compute the confidence level, the process algorithm compares the event of interest with a template pattern corresponding to a known fault. Upon identifying the sequence of interest, based on the calculated confidence level, the system associates the sequence with the known fault. In various embodiments, the confidence level can be stored along with the extracted event data. 
     The threshold for the confidence level indicating the probability of occurrence can be established automatically by the system or entered manually into the system by a system operator via a user communication interface. For example, a confidence level of 1.0 may be specified to indicate a perfect match, which denotes perfect confidence that the event represented in the template has occurred. A confidence level less than 1.0 may be specified to indicate a lower confidence that the event has occurred. 
     For example, by comparing the sequence of interest with the known template, the process algorithm may compute a confidence value of 1.0. This confidence value may be assigned to the sequence of interest and stored to indicate a perfect match. 
     On the other hand, if the process algorithm computes a confidence values less than 1.0, this value can be assigned to the sequence of interest and stored to denote a weaker match. The system may be programmed to indicate for weak matches a lower confidence level that the event of interest occurred. 
     Thus, the system is able to set strong strengths for sequences of interest that have very similar patterns to the known templates and set weak strengths for sequences having less similar patterns. The numeric values described herein are just an example and different numeric ranges can be used in actual operations. 
     In the data correlation approach illustrated in the exemplary embodiment of  FIG. 3 , after relevant time series sequences are identified, in block  300 , the process algorithm may correlate the time series sequences to existing event data stored separately to find extracted time series events. This correlation procedure is particularly useful to reliably predict adverse events, such as failures, before they occur. The relevant time series sequences applied in this approach may be identified using the data extraction approach described above, by using another method, or may be retrieved from a database. 
     In block  302 , the correlation procedure may be performed, for example, by identifying every occurrence of the extracted time series event and then inspecting the event data that chronologically follows that sequence to identify positive cases and negative cases. A set of positive cases indicates that the event to predict is present following the time series sequence. A set of negative cases indicates the event to predict is not present following the sequence. The positive cases may be compiled and used to tune the pattern and calculate the overall accuracy (the predictive power) of the time series sequence. 
     Multiple approaches such as genetic algorithms or Hidden Markov Models may be used to train the patterns to find the positive cases and ignore the negative cases. For example, the system can be trained based on inputs provided by the system operator or trained with data files produced by a component having a known fault associated therewith. 
     In block  304 , the process algorithm stores the sequence data for sequences having a high predictive value. For example, if the predictive value exceeds a predetermined threshold, the sequence is marked as having a high predictive value and is stored in conjunction with the time series pattern. 
     In block  306 , the process algorithm mines historical data contained in a database to create new template patterns for time series sequences that have a high correlation to important events in the event data. The historical time series data represents signals of actual sensor data collected from a component, such as a gas engine, having known faults. 
     In block  308 , as new time series data arrives in the data stream, it can be analyzed in real time to determine how closely it matches a set of template patterns that are known to have detective or predictive value. Sequences of interest may, for example, have a strong match to a template with moderate predictive value, or a moderate match to a template with a strong predictive value. 
     For example, information regarding the time series having a high correlation can be stored as an abstract mathematical model of the collected data to create a data mining model of the template patterns having detective or predictive value. After the data mining model is created, new data can be examined with respect to the model to determine if the data fits a desired pattern or rule. 
     In block  310 , these predictive values can then be used to assess the likelihood of the event (e.g., a temperature sensor exceeding a threshold or manufacturing line shutdown). 
     In block  312 , if the likelihood of occurrence is found to be sufficiently high, then action can be taken to prevent the predicted event from occurring. For example in the data correlation approach, the characteristic or parameters of three sensors that behave in a certain manner may have previously been identified as a known pattern to indicate the occurrence of an event. This known time series pattern can then be applied to time series data in real time to predict that a particular event will occur when the sequence of the known pattern is detected. 
     Based on the prediction, preventative maintenance can be performed to avoid the occurrence of the event. Because a problem or anomaly reported by one component may have repercussions across the entire system, the prediction system  100  can notify the system operator when one component is operating outside its predefined parameters. 
     Based on the predicted sequences of events, the system and/or the system operator can quickly isolate and troubleshoot the problem. Once a predictive sequence has been detected, the system may automatically perform preventative maintenance by adjusting operational parameters of the system. Alternatively or in conjunction with the system, a system operator may be alerted to take the preventative measures. 
     The embodiments illustrated and described above disclose a system and method for associating sequences of time series data with both extracted events and existing events, and quantify the relationship between them. These associations enable real-time assessment of time series data to detect or predict future events. 
     A system and method is provided to annotate a time series data stream with information useful to predict future events in real-time enabling preventative action to be taken to prevent adverse events from occurring. The system and method analyzes time series data to better understand its behavior and identify patterns that can predict the occurrence of an event. 
     Elements of the prediction system  100  described above may be implemented on any general-purpose computer  400  with sufficient processing power, memory resources, and network throughput capability to handle the necessary workload demand.  FIG. 4  illustrates a typical, computer system suitable for implementing one or more embodiments disclosed herein. The general-purpose computer  400  includes a processor  412  (which may be referred to as a central processor unit or CPU) that is in communication with memory devices including secondary storage  402 , read-only memory (ROM)  404 , random access memory (RAM)  406 , input/output (I/O)  408  devices, and network connectivity devices  410 . The processor may be implemented as one or more CPU chips. 
     It is noted that components (simulated or real) associated with the system  100  can include various computer or network components such as servers, clients, controllers, industrial controllers, programmable logic controllers (PLCs), communications modules, mobile computers, wireless components, control components and so forth that are capable of interacting across a network. Similarly, the term controller or PLC as used herein can include functionality that can be shared across multiple components, systems, or networks. 
     For example, one or more controllers can communicate and cooperate with various network devices across the network. This can include any type of control, communications module, computer, I/O device, sensors, Human Machine Interface (HMI) that communicate via the network, or public networks. The controller can also communicate to and control various other devices such as Input/Output modules including Analog, Digital, Programmed/Intelligent I/O modules, other programmable controllers, communications modules, sensors, output devices, and the like. 
     The network can include public networks such as the Internet, Intranets, and automation networks such as Control and Information Protocol (CIP) networks including DeviceNet and ControlNet. Other networks include Ethernet, DH/DH+, Remote I/O, Fieldbus, Modbus, Profibus, wireless networks, serial protocols, and so forth. 
     The secondary storage  402  is typically comprised of one or more disk drives or tape drives and is used for non-volatile storage of data and as an over-flow data storage device if RAM  406  is not large enough to hold all working data. Secondary storage  402  may be used to store programs that are loaded into RAM  406  when such programs are selected for execution. 
     The ROM  404  is used to store instructions and perhaps data that are read during program execution. ROM  404  is a non-volatile memory device that typically has a small memory capacity relative to the larger memory capacity of secondary storage. The RAM  406  is used to store volatile data and perhaps to store instructions. Access to both ROM  404  and RAM  406  is typically faster than to secondary storage  402 . 
     I/O  408  devices may include printers, video monitors, liquid crystal displays (LCDs), touch screen displays, keyboards, keypads, switches, dials, mice, track balls, voice recognizers, card readers, paper tape readers, or other well-known input devices. The network connectivity devices  410  may take the form of modems, modem banks, Ethernet cards, universal serial bus (USB) interface cards, serial interfaces, token ring cards, fiber distributed data interface (FDDI) cards, wireless local area network (WLAN) cards, radio transceiver cards such as code division multiple access (CDMA) and/or global system for mobile communications (GSM) radio transceiver cards, and other well-known network devices. These network connectivity devices  410  may enable the processor  412  to communicate with an Internet or one or more intranets. 
     With such a network connection, it is contemplated that the processor  412  might receive information from the network, or might output information to the network in the course of performing the above-described method steps. Such information, which is often represented as a sequence of instructions to be executed using processor  412 , may be received from and outputted to the network. 
     The processor  412  executes instructions, codes, computer programs, scripts that it accesses from hard disk, floppy disk, optical disk (these various disk-based systems may all be considered secondary storage  402 ), ROM  404 , RAM  406 , or the network connectivity devices  410 . 
     In some embodiments, various functions described above are implemented or supported by a computer program that is formed from computer readable program code and that is embodied in a computer readable medium. The phrase “computer readable program code” includes any type of computer code, including source code, object code, and executable code. The phrase “computer readable medium” includes any type of medium capable of being accessed by a computer, such as read only memory (ROM), random access memory (RAM), a hard disk drive, a compact disc (CD), a digital video disc (DVD), or any other type of memory. 
     Alternative embodiments, examples, and modifications which would still be encompassed by the disclosure may be made by those skilled in the art, particularly in light of the foregoing teachings. Further, it should be understood that the terminology used to describe the disclosure is intended to be in the nature of words of description rather than of limitation. 
     Those skilled in the art will also appreciate that various adaptations and modifications of the preferred and alternative embodiments described above can be configured without departing from the scope and spirit of the disclosure. Therefore, it is to be understood that, within the scope of the appended claims, the disclosure may be practiced other than as specifically described herein.