Method and system for air gap eccentricity detection in a rotating machine

Abstract

Embodiments of the present disclosure disclose a method and system (150) for detecting air gap eccentricity in a rotating machine (100). The method includes receiving, by a processor (202), external leakage flux measurements of the rotating machine (100) from each of a plurality of magnetic sensors (110a, 110b, 110c, 110d). The method includes determining, by the processor (202), a moving average of the external leakage flux measurements received from each of the plurality of magnetic sensors (110a, 110b, 110c, 110d). The method includes determining, by the processor (202), an air gap eccentricity condition of the rotating machine (100) based on a moving average associated with each of the plurality of magnetic sensors (110a, 110b, 110c, 110d).

Description

Technical Field

[0001] The present disclosure relates generally to rotating machines and, more particularly, to methods and systems for air gap eccentricity detection in rotating machines. Background Art

[0002] Rotating machines have long been used to generate power and serve as industrial workhorses. Despite their rugged construction, rotating machines are susceptible to failures that can halt critical processes and cause huge losses. Air gap eccentricity is one of the most common types of failures in rotating machines. Air gap eccentricity refers to a condition where the center of a rotating machine’s rotor is misaligned / misaligned with the center of its stator. More specifically, air gap eccentricity occurs when the distance between the rotor and stator in the air gap of a rotating machine is uneven or asymmetrical. This air gap eccentricity occurs because wear caused by wind, climate, and other operating conditions causes an imbalance that results in an uneven air gap between the stator and rotor. Rotating machines operating with an eccentric air gap can result in increased mechanical vibration, accelerated insulation degradation due to increased coil motion, and potential rotor / stator friction due to unbalanced magnetic pull. If left unchecked, the eccentricity can slowly increase and, in the worst case, can result in the rotor contacting the stator, causing a catastrophic failure. From an operational perspective, the air gap must be kept uniform to prevent rotor damage due to magnetic induction heating, stator frame vibration, increase in the amplitude of the first harmonic of the bearing spectrum, non-uniform magnetic field, wear or cracks in structural components, winding insulation failure, cracks at the connection between the rotor pole and the rim, corrosion of the rotor or stator core, uneven preheating, bearing failure, etc.

[0003] In view of the above discussion, early fault detection and early warning are needed to ensure the full protection and normal operation of rotating machinery.

[0004] The information disclosed in this background section is only for enhancing the understanding of the general background of the invention and should not be considered as an admission or any form of suggestion that the information constitutes the prior art known to a person skilled in the art. Summary of the invention

[0005] In one embodiment, a method for determining air gap eccentricity in a rotating machine is disclosed. The method includes receiving, by a processor, external leakage flux measurements of the rotating machine from each of a plurality of magnetic sensors. The method includes determining, by the processor, a moving average of the external leakage flux measurements received from each of the plurality of magnetic sensors. The method includes determining, by the processor, an air gap eccentricity condition of the rotating machine based on the moving average associated with each of the plurality of magnetic sensors.

[0006] In another embodiment, a system for determining air gap eccentricity in a rotating machine is disclosed. The system includes a memory and a processor. The memory is configured to store instructions. The processor is configured to execute the instructions stored in the memory, thereby being configured to receive external leakage flux measurements of the rotating machine from a plurality of magnetic sensors. The processor is configured to determine a moving average of the external leakage flux measurements received from each of the plurality of magnetic sensors. The processor is configured to determine an air gap eccentricity condition of the rotating machine based on a moving average associated with each of the plurality of magnetic sensors.

[0007] The foregoing summary is for illustrative purposes only and is not intended to limit the invention in any way. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The accompanying drawings are incorporated in and constitute a part of the present disclosure and are used to illustrate exemplary embodiments and, together with the description, to explain the principles disclosed. The same reference numerals are used throughout the drawings to refer to the same features and components. Some embodiments of the apparatus and / or method according to the embodiments of the subject matter of the present invention will now be described by way of example only and with reference to the accompanying drawings, in which:

[0009] Figure 1 A schematic diagram showing an enlarged portion of a rotating machine and an air gap in which at least some embodiments of the present disclosure may be practiced;

[0010] Figure 2 is a block diagram of a system for determining an air gap eccentricity condition in a rotating machine according to one embodiment of the present disclosure;

[0011] Figure 3A shows external leakage flux measurements from a plurality of magnetic sensors of a rotating machine according to one embodiment of the present disclosure, depicting a healthy rotating machine;

[0012] Figure 3B shows external leakage flux measurements from a plurality of magnetic sensors of a rotating machine depicting static eccentricity in the rotating machine according to one embodiment of the present disclosure;

[0013] Figure 3C shows external leakage flux measurements from a plurality of magnetic sensors of a rotating machine depicting dynamic eccentricity in the rotating machine according to one embodiment of the present disclosure;

[0014] Figure 4A is a flow chart illustrating a method for determining dynamic eccentricity in a rotating machine according to one embodiment of the present disclosure;

[0015] Figure 4Bis a flow chart illustrating a method for determining static eccentricity in a rotating machine according to one embodiment of the present disclosure; and

[0016] Figure 5 is a flow chart illustrating a method for determining an air gap eccentricity condition in a rotating machine according to one embodiment of the present disclosure.

[0017] Those skilled in the art will appreciate that any block diagram herein represents a conceptual view of an illustrative system that embodies the subject matter of the present invention. Likewise, it will be appreciated that any flow charts, flow diagrams, state transition diagrams, pseudocodes, etc. represent various processes that can be substantially represented in a computer-readable medium and executed by a computer or processor, whether or not such a computer or processor is explicitly shown. DETAILED DESCRIPTION

[0018] In this document, the word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any embodiment or implementation of the present subject matter described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments.

[0019] Although the present disclosure may have various modifications and alternative forms, its specific embodiments have been shown in the accompanying drawings by way of example and will be described in detail below. However, it should be understood that this does not mean that the present disclosure is limited to the specific form disclosed. On the contrary, the present disclosure covers all modifications, equivalents and alternatives that fall within the spirit and scope of the present disclosure.

[0020] The terms "comprises," "includes," or any other variations are intended to cover a non-exclusive inclusion, so that a device, apparatus, or method that includes a list of components or steps includes not only those components or steps, but may also include other components or steps not expressly listed or inherent in such device, apparatus, or method. In other words, if one or more elements in a device, system, or apparatus are preceded by "comprises...a," it does not exclude the presence of other or additional elements in the device, system, or apparatus without more limitations.

[0021] In the following detailed description of the embodiments of the present disclosure, reference is made to the accompanying drawings which form a part thereof, in which specific embodiments in which the present disclosure may be implemented are shown by way of example. These embodiments are described in sufficient detail to enable those skilled in the art to implement the present disclosure, and it should be understood that other embodiments may be utilized and may be changed without departing from the scope of the present disclosure. Therefore, the following description should not be considered restrictive.

[0022] Figure 1 A schematic diagram of a rotary machine 100 is shown in which at least some embodiments of the present disclosure may be practiced.

[0023] The term "rotating machine" as used herein refers to an energy conversion machine that includes a rotating component (i.e., a rotor) and a stationary component (i.e., a stator). Thus, the rotating machine 100 includes an electric rotating machine equipped with a rotor 102 and a stator 104, which are separated by an air gap 106, as shown in the enlarged portion 180. The air gap 106 is an actual physical gap in the rotating machine 100 that separates the moving rotor 102 from the stator 104. In one example, any machine that performs electromechanical energy conversion through rotational motion is a rotating electric machine. The rotating machine 100 can be an alternating current (AC) machine or a direct current (DC) machine, such as an electric motor, a generator, etc. In this exemplary representation, the rotating machine 100 is an induction motor used in an industrial process.

[0024] Reference is made herein to rotating electrical machines (e.g. Figure 1 The present disclosure is explained with reference to the induction motor shown in FIG. 1 . It should be noted that the rotary machine 100 is hereinafter interchangeably referred to as the rotary electric machine 100. However, it should be noted that various embodiments of the present invention may be practiced with rotary machines other than induction motors. It should be noted that the rotary machine 100 is for exemplary purposes only and the rotary machine 100 may include, for example, Figure 1 In addition, only the components of the rotary machine 100 that are essential to the present disclosure are explained herein, and for the sake of brevity, descriptions of other components of the rotary machine 00 are not provided herein.

[0025] In an exemplary scenario, the air gap 106 shown in the enlarged portion 180 may change in a non-uniform manner due to an air gap eccentricity condition. As used herein, the term "air gap eccentricity" refers to a condition that occurs when there is an uneven or asymmetric distance between the rotor 102 and the stator 104 in the air gap 106 of the rotating machine 100. When there is eccentricity in the air gap 106, the magnetic permeance in the air gap 106 changes, resulting in an unbalanced magnetic flux within the air gap 106. The air gap eccentricity condition may be at least one of the following conditions: static eccentricity and dynamic eccentricity. Static eccentricity occurs when the radial air gap is fixed to a minimum value at the same position of the air gap 106 relative to the stator 104 regardless of the rotor movement. Static eccentricity may be caused by stator core ovality, incorrect positioning of the stator core or bearings during commissioning or maintenance, and the degree of static eccentricity does not change over time. Dynamic eccentricity refers to a condition where the position of the minimum radial air gap is not limited to one position like static eccentricity, but rotates with the rotor 104. In other words, the center of the rotor 104 is not at the center of rotation, but moves, thereby increasing / decreasing the air gap 106 at different locations. This is caused by shaft bending, bearing wear, asymmetric thermal expansion of the rotor 104, etc. When the rotating machine 100 experiences both static eccentricity and dynamic eccentricity, this air gap eccentricity condition is called mixed eccentricity. For example, wear or cracks in the rotor may introduce a mixed air gap eccentricity condition in the rotating machine 100.

[0026] In one embodiment, one or more magnetic sensors 110 (in Figure 1 110a, 110b, 110c, 110d, collectively referred to as "one or more magnetic sensors 110") are used to measure external leakage flux. The external leakage flux is the portion of the magnetic flux generated from the rotating machine 100 that does not follow the expected path in the magnetic circuit, also known as stray flux. Therefore, since there is an air gap 106 between the stator 104 and the rotor 102 of the rotating machine 100, the generation of external leakage flux is a rotating machine (e.g., a rotating machine 100 (in Figure 1 106). It should be noted that the term “external leakage flux measurement value” as used herein refers to the leakage flux outside the rotating machine 100, rather than the leakage flux / magnetic flux within the air gap 106. The external leakage flux measurement value can be used to determine the eccentricity condition of the air gap 106 of the rotating machine 100. Typically, when the air gap 106 of the rotating machine 100 changes, the leakage reactance between the stator 104 and the rotor 102 will also change, and thus the external leakage flux of the rotating machine 100 will also fluctuate to indicate this change in the air gap 106 of the rotating machine 100. Therefore, the air gap eccentricity condition of the electrical rotating machine (i.e., the rotating electric machine 100) can be determined by measuring the external leakage flux of the rotating machine 100.

[0027] In one embodiment, each magnetic sensor 110a, 110b, 110c, 110d of the one or more magnetic sensors 110 may be used to receive external leakage flux measurements around the rotating machine 100. The one or more magnetic sensors 110 may be analog sensors or digital sensors (eg, MEMS-based magnetic sensors).

[0028] In one embodiment, one or more magnetic sensors 110 are located near the rotating machine 100 to receive external leakage flux measurements of the rotating machine 100 for determining an eccentricity condition of the rotating machine 100. More specifically, each of the one or more magnetic sensors 110 can be arranged at a different location near the rotating machine 100 to measure the external leakage flux measurements. In one embodiment, the magnetic sensors 110a, 110b, 110c are disposed on the body 108 of the rotating machine 100, such as Figure 1 As shown. It should be noted that in some existing rotating electrical machines, for example, the rotating machine 100 includes a magnetic field sensor, such as a magnetic sensor 110a on the body 108 of the rotating machine 100, which can be used to capture external leakage flux measurements. In one example, the magnetic sensor 110a mounted on the body 108 of the rotating machine 100 is used to monitor the condition of the rotating machine 100, for example, to identify a broken rotor bar of the rotating machine 100. In one embodiment, the magnetic sensor 110a may also be adapted to measure the external leakage flux generated from the rotating machine 100. It should be noted that although only one magnetic sensor 110a is shown mounted on the body 108 of the rotating machine 100, more than one magnetic sensor, such as magnetic sensors 110b, 110c, 110d, may be mounted at multiple different locations on the body 108 of the rotating machine 100 and at multiple different angles of the rotating machine 100 for measuring the external leakage flux generated by the rotating machine 100.

[0029] In one example, the magnetic sensors 110a, 110b, 110c, and 110d are mounted on the frame of the rotating machine 100 and are evenly distributed, that is, if there are three sensors 110a, 110b, and 110c, each magnetic sensor will be placed 120 degrees apart on the circumference of the frame, and if there are four magnetic sensors 110a, 110b, 110c, and 110d, the magnetic sensors 110a, 110b, 110c, and 110d will be placed 90 degrees apart. In another example, the magnetic sensor 110a can be mounted at any position on the end shield of the rotating machine 100, the magnetic sensor 110b can be mounted at any position on the frame of the rotating machine 100, and the magnetic sensor 110c is installed in the sealed housing of the compressor. It should be noted that the examples described herein are for illustrative purposes, and in general, one or more magnetic sensors 110 may be adapted to be mounted at any location on the rotating machine 100 or near the rotating machine 100 and in any orientation to receive external leakage flux measurements generated by the rotating machine 100 for processing and determining the air gap eccentricity condition of the rotating machine 100. In this exemplary representation, magnetic sensors 110a, 110b, and 110d are shown on the surface (i.e., the frame / rim) of the rotating machine 100, and magnetic sensor 110c is shown on the end cap of the rotating machine 100. It should be noted that magnetic sensors 110a, 110b, 110c, and 110d may be mounted at any location on the rotating machine 100 or adapted to be mounted near the rotating machine 100 to receive external leakage flux measurements of the rotating machine 100. However, it should be noted that the magnetic sensors 110 a , 110 b , 110 c , and 110 d are not placed or mounted anywhere near the air gap 106 because they are non-intrusive sensors for measuring external leakage flux outside the air gap 106 of the rotating machine 100 .

[0030] In this exemplary representation, magnetic sensors 110a, 110b, and 110d are mounted on an outer surface (i.e., a frame) of the rotating machine, while magnetic sensor 110c is mounted on an end cap of the rotating machine 100. It should be noted that when multiple magnetic sensors (e.g., magnetic sensors 110a, 110b, 110c, and 110d) are used, external leakage flux measurements from magnetic sensors 110a, 110b, 110c, and 110d may be analyzed separately to determine air gap eccentricity in the rotating machine 100.

[0031] Various embodiments of the present disclosure disclose a system 150 for air gap eccentricity detection in a rotating machine. In general, the system 150 uses signal processing to analyze external leakage flux measurements received from one or more magnetic sensors 110. A moving average is determined based on each external leakage flux measurement, and an air gap eccentricity condition is determined based on the moving average of each external leakage flux measurement. In addition, the system 150 is further configured to determine the type of air gap eccentricity based on the moving average. In addition, a severity level of the air gap eccentricity condition can be determined to provide notifications that can help schedule maintenance and take timely action. In addition, a control signal can be generated based on a customer-settable fault severity level for actuating a circuit breaker electrically connected to the rotating machine 100. Next, refer to Figure 2-5 The processing of external magnetic leakage flux measurements by system 150 is described.

[0032] Figure 2 A system 150 for determining an air gap eccentricity in a rotating machine 100 is shown according to one embodiment of the present disclosure. In one embodiment, the system 150 is a standalone processor implemented within a control system capable of controlling the operation of an industrial process using the rotating machine 100. More specifically, the system 150 is a relay that operates in real time to trip a circuit breaker of the rotating machine 100 based on a customer-settable fault severity level, as will be described later. In another embodiment, the system 150 is a control system capable of controlling the rotating machine 100. In yet another example, the system 150 is a general-purpose computer configured to perform the operations described herein.

[0033] System 150 is depicted as including processor 202, memory 204, input / output module 206, and communication interface 208. It should be noted that in some embodiments, system 150 may include more or fewer components than depicted herein. The various components of system 150 may be implemented using hardware, software, firmware, or any combination thereof. In addition, the various components of system 150 may be operably coupled to each other. More specifically, the various components of system 150 may be able to communicate with each other using a communication channel medium (e.g., a bus, an interconnect, etc.). It should also be noted that one or more components of system 150 may be implemented in a single server or multiple servers remotely located from each other.

[0034] In one embodiment, the processor 202 may be implemented as a multi-core processor, a single-core processor, or a combination of one or more multi-core processors and one or more single-core processors. For example, the processor 202 may be implemented as one or more of a variety of processing devices, such as a coprocessor, a microprocessor, a controller, a digital signal processor (DSP), a processing circuit with or without an attached DSP, or a variety of other processing devices, including a microcontroller unit (MCU), a hardware accelerator, a dedicated computer chip, etc.

[0035] In one embodiment, the memory 204 is capable of storing machine executable instructions, referred to herein as instructions 205. In one embodiment, the processor 202 is implemented as an executor of software instructions. Thus, the processor 202 is capable of executing the instructions 205 stored in the memory 204 to perform one or more operations described herein. The memory 204 may be any type of memory accessible to the processor 202 to perform the corresponding functions, such as will be referred to in Figure 4A-4B For example, the memory 204 may include one or more volatile or non-volatile memories, or a combination thereof. For example, the memory 204 may be implemented as a semiconductor memory, such as a flash memory, a mask ROM, a PROM (programmable ROM), an EPROM (erasable PROM), a RAM (random access memory), etc.

[0036] In one embodiment, the processor 202 is configured to execute instructions 205 for: (1) determining a moving average of external leakage flux measurements received from each of the plurality of magnetic sensors 110 a, 110 b, 110 c, 110 d, (2) determining an air gap eccentricity condition of the rotating machine 100 based on the moving average associated with each of the plurality of magnetic sensors 110 a, 110 b, 110 c, 110 d, (3) determining a maximum moving average and a minimum moving average based on the moving average associated with the external leakage flux measurements from at least one of the plurality of magnetic sensors 110 a, 110 b, 110 c, 110 d, (4) determining a dynamic index based on the maximum moving average and the minimum moving average, (5) determining the air gap eccentricity condition as dynamic eccentricity when the dynamic index is greater than a dynamic eccentricity threshold, (6) determining a dynamic eccentricity severity level based on the dynamic index, and (7) determining a dynamic eccentricity condition based on the dynamic index received from the plurality of magnetic sensors 110 a, 110 b, 110 c, 110 d. (8) identifying a minimum magnetic flux density distribution from the multiple magnetic flux density distributions as a first reference magnetic flux density distribution, and identifying a maximum magnetic flux density distribution from the multiple magnetic flux density distributions as a second reference magnetic flux density distribution, (9) determining a plurality of magnetic flux density distribution distances based on the multiple magnetic flux density distributions, the first reference magnetic flux density distribution, and the second reference magnetic flux density distribution, (10) determining a distribution difference between a current moment and a previous moment for each of the multiple magnetic flux density distribution distances, (11) determining a static index based on the multiple magnetic flux density distribution distances and the distribution differences, (12) determining an air gap eccentricity condition as static eccentricity when the static index is greater than a static eccentricity threshold, (13) determining an air gap eccentricity condition as static eccentricity when the static index is greater than a static eccentricity threshold, and (14) determining a static eccentricity severity level based on the density distribution difference. Processor 202 may also be configured to execute instructions 205 to: (1) generate a control signal based on at least one of: a dynamic eccentricity severity level and a static eccentricity severity level, and (2) generate a notification based on determining an air gap eccentricity condition of rotating machine 100 .

[0037] In one embodiment, the I / O module 206 may include a mechanism configured to receive input from an operator of the system 150 and provide output. As used herein, the term "operator of the system 150" may refer to one or more individuals directly or indirectly associated with managing the rotating machine 100. In order to be able to receive input and provide output to the system 150, the I / O module 206 may include at least one input interface and / or at least one output interface. The operator of the system 150 may use the I / O module 206 to provide a dynamic eccentricity threshold, a static eccentricity threshold, and a customer-settable fault severity level for actuating the circuit breaker via the input interface. In one example, the severity level (i.e., the dynamic eccentricity severity level and the static eccentricity severity level) may be displayed to the operator of the system 150. In addition, a notification based on determining the air gap eccentricity condition of the rotating machine 100, the type of the air gap eccentricity condition, and the severity level may also be displayed in the output interface. In some embodiments, an alarm may be activated based on the severity level of the air gap eccentricity condition using the output interface. Such warnings based on the customer-settable severity level are very important for reducing damage and planning maintenance of the rotating machine 100.

[0038] Examples of input interfaces may include, but are not limited to, a keyboard, a mouse, a joystick, a keypad, a touch screen, soft keys, a microphone, etc. Examples of output interfaces may include, but are not limited to, a display such as a light emitting diode display, a thin film transistor (TFT) display, a liquid crystal display, an active matrix organic light emitting diode (AMOLED) display, a microphone, a speaker, a ringer, etc.

[0039] The communication interface 208 may include a mechanism configured to communicate with an external entity / peripheral device, such as one or more magnetic sensors 110a, 110b, 110c, 110d associated with the rotating machine 100, a remote server, etc. In other words, the communication interface 208 is configured to receive external leakage flux measurements from each of the one or more magnetic sensors 110 for processing by the processor 202. As already explained, the external leakage flux measurements are performed by one or more magnetic sensors 110 mounted on the rotating machine 100 or placed near the body 108 of the rotating machine 100 in order to measure the external leakage flux of the rotating machine 100. In one embodiment, the external leakage flux measurements are forwarded to the processor 202, which performs one or more operations described herein to detect air gap eccentricity in the rotating machine 100. It should be noted that the external leakage flux measurements received from the one or more magnetic sensors 110 may be conditioned before being processed by the processor 202. Therefore, the system 150 may include other components for pre-processing the external leakage flux measurements received from the one or more magnetic sensors 110, such as a signal conditioner ( Figure 2). In general, signal conditioning is the process of manipulating an analog signal (here, a "magnetic flux measurement") in such a way that the analog signal is optimized for further processing. Thus, signal conditioning of the magnetic flux measurement may include, but is not limited to, amplification, filtering, continuous amplification, conversion, range matching, isolation, and any other process that makes the sensor output of the magnetic sensor suitable for processing after conditioning. In general, such signal conditioning of the magnetic flux measurement may be performed to eliminate unwanted noise, improve resolution, improve signal-to-noise ratio (SNR), convert to other forms, etc. In one embodiment, the external leakage flux measurement of each of the plurality of magnetic sensors 110a, 110b, 110c, 110d is a direct current (DC) component. More specifically, a moving average filter is used as part of preprocessing to generate a DC component of the external leakage flux measurement, which may be further processed to detect air gap eccentricity and the severity level of air gap eccentricity in the rotating machine 100. In another embodiment, the external leakage flux measurement of each of the plurality of magnetic sensors 110a, 110b, 110c, 110d includes an alternating current (DC) component.

[0040] The system 150 is depicted as being in operable communication with a database 220. In one embodiment, the database 220 is configured to store one or more machine parameters related to the rotating machine managed by the system 150. Some examples of machine parameters include, but are not limited to, air gap measurements, rotor specifications, stator specifications, etc. The database 220 may include multiple storage units, such as hard disks and / or solid state disks in a redundant array of inexpensive disks (RAID) configuration. In some embodiments, the database 220 may include a storage area network (SAN) and / or a network attached storage (NAS) system. In one embodiment, the database 220 may correspond to a distributed storage system, wherein each database is configured to store custom information, such as air gap eccentricity monitoring strategies, a list of rotating machines, air gap eccentricity conditions of rotating machines over time, detailed information of fault conditions, severity levels, maintenance data, historical data of external leakage flux measurements, dynamic eccentricity thresholds, static eccentricity thresholds, notifications, etc.

[0041] In some embodiments, database 220 is integrated into system 150. For example, system 150 may include one or more hard disk drives as database 220. In other embodiments, database 220 is external to system 150 and can be accessed by system 150 using a storage interface ( Figure 2The storage interface is any component capable of providing the processor 202 with access to the database 220. The storage interface may include, for example, an Advanced Technology Attachment (ATA) adapter, a Serial ATA (SATA) adapter, a Small Computer System Interface (SCSI) adapter, a RAID controller, a SAN adapter, a network adapter, and / or any component that provides the processor 202 with access to the database 220.

[0042] As previously described, the communication interface 208 is configured to receive external leakage flux measurements from each of the one or more magnetic sensors 110 and forward the flux measurements to the processor 202. The processor 202, in conjunction with the instructions in the memory 204, is configured to process the external leakage flux measurements for detecting air gap eccentricity in the rotating machine 100. As previously described, the external leakage flux measurements may correspond to leakage flux generated by the rotating machine 100 (i.e., a rotating electrical machine) due to changes in the air gap 106 between the stator 104 and the rotor 102 of the rotating machine 100. It should be noted that the external leakage flux measurements are captured outside the rotating machine 100, and the one or more magnetic sensors 110 do not measure the external leakage flux anywhere in the air gap 106 of the rotating machine 100.

[0043] More specifically, the external leakage flux measurements may be used to identify air gap eccentricity conditions in the rotating machine 100. Eccentricity conditions in the rotating machine 100 occur mostly due to excessive wear, manufacturing / installation errors, extreme operating conditions causing imbalance resulting in changes in the air gap 106 between the stator 104 and the rotor 102. As a result, these eccentricity conditions may result in increased mechanical vibrations, accelerated insulation degradation due to increased coil motion, and possible rotor 102 / stator 104 friction due to unbalanced magnetic pull, and in extreme cases, the rotor 104 may contact the stator 102, resulting in catastrophic failure. Some examples of air gap eccentricity conditions in the rotating machine 100 include, but are not limited to, static eccentricity, dynamic eccentricity, and mixed eccentricity. Next, refer to Figures 3A-3C Examples of external leakage flux measurements from one or more magnetic sensors 110 are shown and described that describe different types of eccentricity conditions.

[0044] Reference now Figure 3A, according to one embodiment of the present disclosure, diagram 300 depicts external leakage flux measurements of magnetic sensors 110a, 110b, 110c, and 110d of a rotating machine 100, depicting a healthy air gap. In one example, once the rotating machine 100 is installed, the external leakage flux measurements shown in diagram 300 can be captured by one or more magnetic sensors 110a, 110b, 110c, and 110d. In this exemplary representation, the external leakage flux measurements from magnetic sensor 110a are shown by diagram 305, the external leakage flux measurements from magnetic sensor 110b are shown by diagram 310, the external leakage flux measurements from magnetic sensor 110c are shown by diagram 315, and the external leakage flux measurements from magnetic sensor 110d are shown by diagram 320. It should be noted that diagram 300 depicts a healthy air gap 106 of rotating machine 100 (i.e., an air gap without an eccentricity condition) after rotating machine 100 is installed for example purposes only, and air gap 106 of rotating machine 100 may be in a healthy state without an eccentricity condition even after years of operation.

[0045] from Figure 3A It can be seen that the external leakage flux measurements from the magnetic sensors 110a, 110b, 110c, and 110d change in a uniform / consistent manner over time, and therefore, no air gap eccentricity is apparent from the graphs 305, 310, 315, and 320. As previously described, when the air gap 106 of the rotating machine 100 changes, the leakage reactance between the stator 104 and the rotor 102 also changes, and therefore the external leakage flux measurements of the rotating machine 100 from some magnetic sensors (e.g., 110a, 110b) may deviate from other magnetic sensors (110c, 110d) to indicate such a change in the air gap 106 of the rotating machine 100. However, since the air gap 106 of the rotating machine 100 does not change, the external leakage flux measurements appear consistent in the graphs 305, 310, 315, and 320. However, if the air gap 106 of the rotating machine 100 is not uniform, the external leakage flux measurements shown in graphs 305, 310, 315, and 320 will change to indicate air gap eccentricity, as will be described below with reference to Figure 3B-3C Explanatory.

[0046] Now refer to Figure 3B, shows external leakage flux measurements from magnetic sensors 110a, 110b, 110c, and 110d, depicting static eccentricity in a rotating machine 100, according to one embodiment of the present disclosure. In one example, once the rotating machine 100 is installed, one or more magnetic sensors 110a, 110b, 110c, and 110d can capture the external leakage flux measurements shown in diagram 330. For example, misalignment during motor assembly may result in an uneven air gap between the rotor 104 and the stator 102 of the rotating machine 100, where the stator 102 is stationary relative to the rotor 104.

[0047] In this exemplary representation, external leakage flux measurements from magnetic sensor 110a are shown by graph 335, external leakage flux measurements from magnetic sensor 110b are shown by graph 340, external leakage flux measurements from magnetic sensor 110c are shown by graph 345, and external leakage flux measurements from magnetic sensor 110d are shown by graph 350. It should be noted that graph 330 depicts static eccentricity in rotating machine 100 just after installation of rotating machine 100 for exemplary purposes only, and that static eccentricity in air gap 106 may result from bearing wear in stator 104 of rotating machine 100.

[0048] from Figure 3BIt can be seen that the external leakage flux measurements from magnetic sensors 110a, 110b, 110c, and 110d show different distributions. For example, the external leakage flux measurements from magnetic sensor 110d show a greater spread / distribution (see diagram 350) than the external leakage flux measurements from other magnetic sensors 110a, 110b, 110c (see diagrams 335, 340, 345). The external leakage flux measurements from magnetic sensors 110a, 110b, 110c, and 110d appear consistent but have different distributions, indicating that there is static eccentricity in the air gap 106 of the rotating machine 100. In general, when the external leakage flux measurements from each magnetic sensor change uniformly over time, their distributions show that the external leakage flux measurements of each magnetic sensor 110a, 110b, 110c, and 110d are more dispersed in diagram 330, indicating the presence of static eccentricity. In general, when the air gap 106 of the rotating machine 100 increases / decreases at a specific position, the leakage reactance between the stator 104 and the rotor 102 also changes based on the position, and therefore, the external leakage flux measurement values ​​of the rotating machine 100 from one magnetic sensor (e.g., the magnetic sensor 110d) may have different distributions to show the increase or decrease of the air gap 106. It should be noted that in order to detect the static eccentricity of the air gap 106 of the rotating machine 100, the external leakage flux measurement values ​​from multiple magnetic sensors (i.e., at least three magnetic sensors 110a, 110b, 110c) are required to determine the distribution or spread, and the reference Figure 4B Let's explain this in detail.

[0049] Now refer to Figure 3C , shows external leakage flux measurements from magnetic sensors 110a, 110b, 110c, 110d according to one embodiment of the present disclosure, depicting dynamic eccentricity in the rotating machine 100. As previously described, dynamic eccentricity is a condition in the rotating machine 100 where the center of the rotor 102 is not at the center of rotation and the location of the minimum radial air gap rotates with the rotor 102. Therefore, due to dynamic eccentricity, the external leakage flux measurements fluctuate as the air gap 106 changes.

[0050] In this exemplary representation, external leakage flux measurements from magnetic sensor 110a are shown by diagram 365, external leakage flux measurements from magnetic sensor 110b are shown by diagram 370, external leakage flux measurements from magnetic sensor 110c are shown by diagram 375, and external leakage flux measurements from magnetic sensor 110d are shown by diagram 380. It should be noted that diagrams 365, 370, 375, and 380 are for exemplary purposes only, and these diagrams can be changed in a manner different from that shown herein to indicate dynamic eccentricity. It should be noted that external leakage flux measurements from a single magnetic sensor (e.g., magnetic sensor 110a) can be used to determine dynamic eccentricity. More specifically, fluctuations displayed by one magnetic sensor can be used to determine changes in external leakage flux measurements, and the changes can be used to identify dynamic eccentricity of rotating machine 100.

[0051] from Figure 3C It can be seen that the external leakage flux measurements from magnetic sensors 110a, 110b, 110c, and 110d vary in a non-uniform manner over time. More specifically, the maximum and minimum values ​​observed over a period of time for the external leakage flux measurements from magnetic sensor 110a show significant fluctuations (see graph 365). For example, the maximum value of the external leakage flux measurement (v max1 ,v max2 ,v max3 ,…) and minimum value (v min1 ,v min2 ,v min3 ,…) is not like Figure 3A Such significant fluctuations in the external leakage flux measurements of the magnetic sensor 110 a (ie, the maximum and minimum values ​​of the external leakage flux measurements) indicate the presence of dynamic eccentricity in the rotating machine 100 . Figure 3C Graphs 370, 375, and 380 of show similar fluctuations and the fluctuations shown in the external leakage flux measurement of one magnetic sensor (e.g., the magnetic sensor) may be sufficient to determine a dynamic eccentricity condition. Therefore, if the system 150 is used only to measure a dynamic eccentricity condition in the rotating machine 100, the external leakage flux measurement from a single magnetic sensor is sufficient to detect the dynamic eccentricity of the air gap 106 of the rotating machine 100. Generally speaking, when the minimum radial air gap rotates with the rotor 102 during dynamic eccentricity, the air gap 106 in the rotating machine 100 increases / decreases as the rotor rotates at different positions, which causes the leakage reactance between the stator 104 and the rotor 102 to fluctuate based on the minimum air gap position, and therefore, the external leakage flux measurement of the rotating machine 100 from one magnetic sensor (e.g., the magnetic sensor 110a) may show significant changes (i.e., the difference between the maximum and minimum values ​​of the external leakage flux measurement), indicating a dynamic eccentricity condition in the rotating machine 100. Reference Figure 2 Description These external leakage flux measurements are processed to determine the air gap eccentricity condition.

[0052] Now refer to Figure 2 , processor 202 receives the external leakage flux measurements and performs analysis to determine an air gap eccentricity condition of rotating machine 100 , as described below.

[0053] In one embodiment, the processor 202 is configured to determine a moving average of external leakage flux measurements received from each of the plurality of magnetic sensors 101a, 101b, 101c, and 101d. More specifically, the external leakage flux measurements from each magnetic sensor (e.g., magnetic sensor 110a) may be analyzed in a smaller window (e.g., a 20 millisecond window). Thus, the moving average of the external leakage flux measurements from the magnetic sensor (e.g., magnetic sensor 110a) includes a series of average values ​​(a,b) of different selections of the external leakage flux measurements. 1 ,a 2 ,a 3 ,...). Generally speaking, the external leakage flux measurements analyzed are located in smaller windows, which are also referred to herein as "window signals". In one embodiment, these smaller windows are overlapping windows. In one example, the moving average of the external leakage flux measurements is given by equation (1) shown below.

[0054]

[0055] Where LF(i,k) is the leakage flux measurement from the external sensor at the i-th moment, 'k' and 'Ns' are the number of samples in the power cycle.

[0056] In one embodiment, the air gap eccentricity condition of the rotating machine 100 is determined based on a moving average value associated with each of the plurality of magnetic sensors 110a, 110b, 110c, 110d. In one example, if a series of average values ​​(a) of different portions of the external leakage flux measurement values ​​received from one magnetic sensor (e.g., magnetic sensor 110a) are 1 ,a 2 ,a 3 ,…,a n ) and a series of average values ​​(b) of corresponding portions of external leakage flux measurements received from another magnetic sensor (e.g., magnetic sensor 110b) 1 ,b 2 ,b 3 ,…,b n) are the same, then there is no air gap eccentricity condition in the rotating machine 100. It should be noted that when comparing the moving averages of the two magnetic sensors (i.e., magnetic sensors 110a, 110b), slight variations in the moving averages are acceptable due to the relative positions of the magnetic sensors on the rotating machine 100.

[0057] However, if a series of average values ​​(a) of different portions of external leakage flux measurements received from a magnetic sensor (e.g., magnetic sensor 110a) are 1 ,a 2 ,a 3 ,…,a n ) itself and / or a series of average values ​​(b) of corresponding portions of external leakage flux measurements received from another magnetic sensor (e.g., magnetic sensor 110b) 1 ,b 2 ,b 3 ,…,b n ) is significantly different, then there is an air gap eccentricity condition in the rotating machine 100. Therefore, the processor 202 is configured to further analyze the moving average of each of the plurality of magnetic sensors 110a, 110b, 110c, and 110d to determine the type of eccentricity condition. As previously described, the air gap eccentricity condition can be determined as one of the following: dynamic eccentricity, static eccentricity, or mixed eccentricity. The following will describe processing the external leakage flux measurement value to determine the dynamic eccentricity in the rotating machine 100.

[0058] In one embodiment, the processor 202 is configured to determine a maximum moving average value (maxLF) based on moving average values ​​associated with external leakage flux measurements from at least one of the plurality of magnetic sensors 110a, 110b, 110c, 110d. MA (n,k)) and the minimum moving average (minLF MA As previously mentioned, a moving average of external leakage flux measurements from a single magnetic sensor (e.g., magnetic sensor 110a) may be sufficient to determine dynamic eccentricity. In one example, if leakage flux measurements from magnetic sensor 110a are considered, then a series of average values ​​a 1 ,a 2 ,a 3 ,…,a n The maximum moving average value (ie, minLF MA (n,k)=a max ) and the minimum moving average (minLF MA (n,k)=a minIn one embodiment, the maximum moving average and the minimum moving average are determined based on equations (2) and (3), respectively.

[0059] maxLF MA (n,k)=max(maxLF MA (n-1,k),LF MA (n,k)) (2)

[0060] minLF MA (n,k)=min(minLF MA (n-1,k),LF MA (n,k)) (3)

[0061] In one embodiment, the processor 202 is configured to calculate the maximum moving average value (minLF MA (n,k)) and the minimum moving average (minLF MA (n, k)) to determine the dynamic index. More specifically, the change in the external leakage flux measurement value is determined based on the maximum moving average and the minimum moving average determined based on the external leakage flux measurement value received from the magnetic sensor 110a. The change in the maximum moving average and the minimum moving average represents the dynamic index. The change in the external leakage flux measurement value can be determined as shown in equation (4).

[0062]

[0063] However, it should be noted that the external leakage flux measurements from each of the plurality of magnetic sensors 110a, 110b, 110c, 110d may also be analyzed separately to determine the dynamic eccentricity. More specifically, the method described above may be used to determine the dynamic eccentricity based on the external leakage flux measurements performed by each of the plurality of magnetic sensors 110a, 110b, 110c, 110d in the rotary machine 100. In one embodiment, the dynamic index is determined based on the maximum moving average and the minimum moving average determined based on the external leakage flux measurements of each of the plurality of magnetic sensors 110a, 110b, 110c, 110d, as shown in equation (5).

[0064]

[0065] Where S is the number of external leakage flux sensors.

[0066] In one embodiment, when the dynamic index is greater than a dynamic eccentricity threshold, the air gap eccentricity condition is determined to be a dynamic eccentricity. The dynamic eccentricity threshold is a customer-settable value for identifying a fault in the air gap 106 of the rotating machine 100. In one example, the dynamic eccentricity threshold may be set to 0.2. Whenever the dynamic index exceeds the dynamic eccentricity threshold (e.g., 0.2), the air gap eccentricity condition is determined to be a dynamic eccentricity of the air gap 106 of the rotating machine, as shown in equation (6) below. Additionally, if the dynamic index is less than the dynamic eccentricity threshold (e.g., 0.2), there is no eccentricity condition of the air gap 106 of the rotating machine 100, as may be apparent from equation (6) shown below.

[0067]

[0068] The processor 202 is further configured to determine a dynamic eccentricity severity level based on the dynamic index. An example of determining the dynamic eccentricity severity level is shown in the following equation (7):

[0069] dynSeverity(n)=100*dynIndex(n)% (7)

[0070] In addition, a control signal can be generated based on a customer-settable fault severity level for actuating a circuit breaker electrically coupled to the rotating machine 100. More specifically, an operator of the system 150 can specify a dynamic eccentricity severity level so that a fault in the rotating machine 100 (i.e., an air gap eccentricity condition) above a specified value can trigger a circuit breaker circuit to disconnect the rotating machine 100 from other circuits to prevent catastrophic failure. Processing leakage flux measurements from the plurality of magnetic sensors 110a, 110b, 110c, 110d to determine static eccentricity will be described below.

[0071] In one embodiment, the processor 202 is configured to determine a plurality of magnetic flux density distributions based on a moving average of external leakage flux measurements received from each of the plurality of magnetic sensors 110a, 110b, 110c, 110d. More specifically, the magnetic flux density distributions LF MA (n,1:S) is determined based on external leakage flux measurements from a magnetic sensor (eg, magnetic sensor 110a).

[0072] In one embodiment, the minimum magnetic flux density distribution and the maximum magnetic flux density distribution among the plurality of magnetic flux density distributions are identified as the first reference magnetic flux density distribution and the second reference magnetic flux density distribution. More specifically, the plurality of magnetic flux density distributions (LF MA (n,1),LF MA (n,2),LF MA(n,3),LF MA (n, 4)) are compared with each other to determine a first reference magnetic flux density distribution (ie, minValSensor) and a second reference magnetic flux density distribution (ie, maxValSensor) represented by the following equation (8).

[0073]

[0074] In one embodiment, multiple magnetic flux density distribution distances are determined based on multiple magnetic flux density distributions. More specifically, the magnetic flux density distribution distance between each of the multiple magnetic flux density distributions and each of the first reference magnetic flux density distribution (minValSensor) and the second reference magnetic flux density distribution (minValSensor) is determined. Therefore, the magnetic flux density distribution distance between the first reference magnetic flux density distribution / the second reference magnetic flux density distribution and each of the multiple magnetic flux density distributions is determined based on equation (9) shown below.

[0075]

[0076] In one example, if the magnetic flux density distribution LF MA (n,2) has the minimum magnetic flux density distribution and LF MA (n,4) has the maximum magnetic flux density distribution, then LF MA (n,2) and LF MA (n, 4) can be determined as the first reference magnetic flux density distribution and the second reference magnetic flux density distribution, respectively. MA (n,2) and LF MA (n,4)) and the magnetic flux density distribution LF MA (n,1),LF MA (n,2),LF MA (n,3),LF MA (n,4) to determine the distance value as shown below based on the first / second reference magnetic flux density distribution respectively: (i.e., distVal(n,1) least ,distVal(n,2) least ,distVal(n,3) least ,distVal(n,4) least ,distVal(n,1) max ,distVal(n,2) max ,distVal(n,3) max ,distVal(n,4) max). It should be noted that the technique described above for determining the distance value of the magnetic flux density distribution is for example purposes only, and any other statistical technique may be used to determine the distance between the reference magnetic flux density distribution and the other magnetic flux density distributions.

[0077] In some embodiments, multiple magnetic flux density distribution distances may be normalized before further processing. In one example, each magnetic flux density distribution distance may be normalized by dividing the magnetic flux density distribution distance value by an average value. To achieve this effect, an average value may be determined based on a moving average value determined from external leakage flux measurements received from multiple magnetic sensors 110a, 110b, 110c, and 110d. For example, the magnetic flux density distribution distance may be normalized as shown in the following equation (10).

[0078]

[0079] The processor 202 is also configured to determine a change in the normalized magnetic flux density distribution distance (ie, δnorm) for each magnetic sensor with respect to a previous time (ie, n-1) to determine a distribution difference. distDiff(n,1:S) least,max =distValNorm(n,1:S) least,max -distValNorm(n-1,1:S) least,max (11)

[0081] In one example, the normalized magnetic flux density distribution distance of the sensor 110a is determined at a time (distValNorm(n,1) least ) and the previous moment (distValNorm(n-1,1) least ) distribution difference distDiff(n,1) least Similarly, the distribution difference between the current moment and the previous moment is determined for each of the plurality of magnetic flux density distribution distances.

[0082] In one embodiment, the static index (ie, statIndex(n)) is the normalized magnetic flux density distribution distance value (ie, distValNorm(n,1:S)) exceeding the distance threshold. least,max ) (in the distribution of differences distDiff(n,1:S) least,max is less than the difference threshold), as shown in equation (12) below.

[0083]

[0084] In one example, the distance threshold may be 5% and the difference threshold may be 0.1. Thus, there are multiple normalized magnetic flux density distribution distances (distValNorm(n,1)) that are checked against the distance thresholds. least ,distValNorm(n,2) least ,distValNorm(n,3) least ,distValNorm(n,4) least ,distValNorm(n,1) max ,distValNorm(n,2) max ,distValNorm(n,3) max ,distValNorm(n,4) max ) and multiple distribution differences distDiff(n,1) checked against a difference threshold least ,distDiff(n,2) least ,distDiff(n,3) least ,distDiff(n,4) least ,distDiff(n,1) max ,distDiff(n,2) max ,distDiff(n,3) max ,distDiff(n,4) max .

[0085] In one example, statIndex(n) is only valid if disValNorm(n,1) least Exceeds the distance threshold and the corresponding distDiff(n,1) least It is 1 only when it is less than the difference threshold.

[0086] In one embodiment, when the static index statIndex(n) is greater than a static eccentricity threshold, the air gap eccentricity condition is determined to be a static eccentricity. The static eccentricity condition of the air gap 106 of the rotary machine 100 is identified using equation (13) shown below.

[0087]

[0088] In one example, the static eccentricity threshold may be 2.

[0089] In addition, the processor 202 is configured to calculate the normalized magnetic flux density distribution distV alNorm(n,1:S) based on the normalized magnetic flux density distribution distV alNorm(n,1:S) least,max In one example, the static eccentricity level is compared with the reference magnetic flux density distribution (LF MA (n,1:2),LFMA (n,4)) and other magnetic flux density distributions The normalized distance value associated with the distance between least ,distValNorm(n,2) least ,distValNorm(n,3) least ,distValNorm(n,4) least ,distValNorm(n,4) least ,distValNorm(n,1) max ,distValNorm(n,2) max ,distValNorm(n,4) max ). An example of determining the static eccentricity severity level is shown in equation (14) below.

[0090] statSeverity(n)=max(distValNorm(n,1:S) least,max ) (14)

[0091] Furthermore, a control signal is generated based on a customer-settable static eccentricity severity level for actuating a circuit breaker electrically coupled to the rotating machine 100. More specifically, an operator of the system 150 may specify a static eccentricity severity level such that a fault in the rotating machine 100 (i.e., an air gap eccentricity condition) above a specified value may trigger a circuit breaker to disconnect the rotating machine 100 from other circuits to prevent a catastrophic failure.

[0092] In one embodiment, the processor 202 is configured to forward information related to the air gap eccentricity condition in the rotating machine 100 (e.g., the type of air gap eccentricity, the severity level) to the communication interface 208. The communication interface 208 can transmit the information related to the air gap eccentricity condition to the central server for further analysis and action, for example, data related to the type of air gap eccentricity, the severity level, which can be stored and visualized in the form of a report. In another embodiment, the communication interface 208 can forward information related to the severity level of the air gap eccentricity condition in the rotating machine 100 to an alarm circuit (not shown in the figure), which generates an alarm signal based on a threshold value set by a customer. The alarm circuit can provide an audible or visual alarm based on the air gap eccentricity condition. In another embodiment, the processor 202 can forward information associated with the air gap eccentricity condition to the I / O module 206. The I / O module 206 can display an appropriate alarm based on the air gap eccentricity condition of the rotating machine 100. For example, an output interface such as a ringer, a speaker, and a display can be used to generate an alarm signal for an operator of the system 150. In one example, the severity levels may be displayed to an operator of system 150 so that maintenance activities for rotating machine 100 may be planned in advance.

[0093] In one embodiment, the rotating machine 100 may exhibit both static eccentricity and dynamic eccentricity, in which case the air gap eccentricity condition is referred to as mixed eccentricity. It should be noted that the type of eccentricity condition, including dynamic eccentricity and static eccentricity, can be determined by evaluating the external leakage flux measurements from the plurality of magnetic sensors 110a, 110b, 110c, 110d.

[0094] As previously mentioned, external leakage flux measurements from the plurality of magnetic sensors 110a, 110b, 110c, 110d may be needed to determine the static eccentricity of the air gap 106 of the rotating machine 100. However, it should be noted that if the rotating machine 100 is specifically evaluated for dynamic eccentricity, external leakage flux measurements from any one of the plurality of magnetic sensors 110a, 110b, 110c, 110d may be sufficient. Figure 4A An exemplary flow chart depicting a method for determining dynamic eccentricity in a rotating machine is shown and described.

[0095] Figure 4A 1 is a flow chart illustrating a method 400 for determining dynamic eccentricity in a rotary machine 100 according to one embodiment of the present disclosure. As previously described, dynamic eccentricity is a condition in which the position of the minimum radial air gap is not confined to one position like static eccentricity, but rotates with the rotor 104. Therefore, dynamic eccentricity is determined by a dynamic index, which is a measure of the difference between the maximum moving average and the minimum moving average.

[0096] At 402 of method 400, external leakage flux measurements of rotating machine 100 are received from at least one magnetic sensor (e.g., magnetic sensor 110a). It should be noted that external leakage flux measurements from a single sensor are sufficient to determine dynamic eccentricity, as will be described below. If external leakage flux measurements are received from more than one magnetic sensor, the external leakage flux measurements from each magnetic sensor are evaluated separately to determine whether dynamic eccentricity exists in air gap 106 of rotating machine 100.

[0097] At 404 of method 400, a moving average of external leakage flux measurements received from at least one magnetic sensor 110a is determined. A moving average is a series of averages of different portions of external leakage flux measurements of a magnetic sensor (ie, 110a) analyzed in a smaller window.

[0098] At 406 of method 400, a maximum moving average and a minimum moving average are determined based on the moving averages associated with the external leakage flux measurements from at least one magnetic sensor. For example, a maximum moving average (maxLF MA (n,k)) and the minimum moving average (minLF MA (n,k)).

[0099] At 408 of method 400, a dynamic indicator is determined based on the maximum moving average and the minimum moving average. More specifically, the dynamic indicator is a representation of the change in the external leakage flux measurement value (i.e., the external leakage flux measurement value associated with the magnetic sensor 110) determined based on the moving average. In one example, the dynamic indicator is determined based on equations (4) and (5). It should be noted that equations (4) and (5) are for example purposes only, and any signal processing technique for determining a change or change in the external leakage flux measurement value can be used to determine the dynamic indicator.

[0100] At 410 of method 400 , a determination is made as to whether the dynamic index is greater than a dynamic eccentricity threshold. The dynamic eccentricity threshold is a customer-settable value that may be provided by an operator of system 150 .

[0101] At 412 of method 400, when the dynamic indicator is greater than the dynamic eccentricity threshold, the air gap eccentricity condition is determined to be a dynamic eccentricity. If the dynamic indicator is less than the dynamic eccentricity threshold, then no dynamic eccentricity is detected in the rotary machine 100. When the dynamic indicator is less than the dynamic eccentricity threshold, the system 150 continues to monitor the air gap 106 of the rotary machine 100 to detect an air gap eccentricity condition.

[0102] At 414 of method 400, a dynamic eccentricity severity level is determined based on the dynamic indicator. An example of determining the dynamic eccentricity severity level is shown in equation (7). The dynamic eccentricity severity level indicates a measurement of the air gap eccentricity condition (here, dynamic eccentricity) that can enable an operator of the system 100 to schedule maintenance and take timely action. Figure 4B An exemplary method of determining the static eccentricity of the air gap 106 of the rotating machine 100 is described.

[0103] Figure 4B is a flow chart illustrating a method 450 for determining static eccentricity in a rotary machine 100 according to one embodiment of the present disclosure.

[0104] At 452 of method 450 , external leakage flux measurements of the rotating machine 100 are received by a system (eg, system 150 ) from each of the plurality of magnetic sensors 110 a , 110 b , 110 c , and 110 d .

[0105] At 454 of method 450 , a moving average of the external leakage flux measurements received from each of the plurality of magnetic sensors 110 a , 110 b , 110 c , and 110 d is determined.

[0106] At 456 of method 450 , a plurality of magnetic flux density distributions are determined based on a moving average of the external leakage flux measurements received from each of the plurality of magnetic sensors 110 a , 110 b , 110 c , and 110 d .

[0107] At 458 of method 450 , a minimum magnetic flux density distribution among the plurality of magnetic flux density distributions is identified as a first reference magnetic flux density distribution, and a maximum magnetic flux density distribution among the plurality of magnetic flux density distributions is identified as a second reference magnetic flux density distribution.

[0108] At 460 of method 450, a plurality of magnetic flux density distribution distances are determined based on the plurality of magnetic flux density distributions, the first reference magnetic flux density distribution, and the second reference magnetic flux density distribution. More specifically, each magnetic flux density distribution distance is determined by comparing each of the plurality of magnetic flux density distributions with each of the first reference magnetic flux density distribution and the second reference magnetic flux density distribution. The determination of the plurality of magnetic flux density distribution distances has been made with reference to Figure 2 For the sake of brevity, it will not be repeated here.

[0109] At 462 of method 450 , a distribution difference between a current time and a previous time for each of a plurality of magnetic flux density distribution distances is determined.

[0110] At 464 and 466 of method 450, a static indicator is determined based on a plurality of magnetic flux density distribution distances (see operation 460) and distribution differences, such as reference Figure 2 As described.

[0111] At 468 of method 450, when the static indicator is greater than the static eccentricity threshold, the air gap eccentricity condition is identified as static eccentricity. If the static indicator is less than the static eccentricity threshold, there is no static eccentricity in the rotary machine 100, and the system 150 continues to evaluate the external leakage flux measurements received from each of the plurality of magnetic sensors 110a, 110b, 110c, 110d.

[0112] At 470 of method 450, a static eccentricity severity level is determined based on the plurality of magnetic flux density distribution distances determined in operation. Examples of determining the static eccentricity severity level are shown in equations (10) and (14).

[0113] It should be noted that although reference Figure 1 The induction motor shown illustrates the determination of the air gap eccentricity condition in the rotary machine 100, but the various embodiments of the present disclosure can also be used in any other rotary machine with electrical conduction without departing from the scope of the present disclosure. More specifically, any rotary machine with an air gap and generating leakage flux can implement the embodiments according to the present disclosure to determine the air gap eccentricity condition. Figure 5 A method for determining an air gap eccentricity condition in a rotating machine 100 is described.

[0114] Figure 5 is a flow chart showing a method 500 for determining an air gap eccentricity condition in a rotating machine according to one embodiment of the present disclosure. The method 500 shown in the flow chart may be performed by, for example Figure 2 The operations of the flowchart and combinations of the operations in the flowchart may be implemented by, for example, hardware, firmware, a processor, a circuit, and / or different devices associated with the execution of software including one or more computer program instructions. The operations of the method 500 are described herein with reference to the processor 202 of the system 150. It is worth noting that the operations of the method 500 may be described and / or practiced by using one or more processors of a system / device other than the processor 202. The method 500 begins with operation 502.

[0115] At operation 502 of method 500, a processor, for example, references Figure 2The processor 202 shown and described receives external leakage flux measurements of the rotating machine 100 from each of the plurality of magnetic sensors 110a, 110b, 110c, 110d. As previously described, the processor 202 can be implemented within a control system (e.g., a relay) that is capable of controlling the operation of an industrial process using the rotating machine 100. In another embodiment, the system 150 is a control system that controls the rotating machine 100, or can be configured as a stand-alone processor that is configured to perform one or more operations described herein. In some embodiments, the processor 202 can be configured in a centralized / cloud application where it will periodically receive external leakage flux measurements and provide information about any evolving air gap eccentricity conditions. The external leakage flux measurements are made outside the air gap 106 of the rotating machine 100, thereby eliminating the need for structural changes that may be required when deploying the magnetic sensors 110a, 110b, 110c, 110d.

[0116] At operation 504 of method 500, a moving average of the external magnetic flux leakage measurements received from each of the plurality of magnetic sensors is determined. More specifically, the moving average is determined as a series of averages based on the external magnetic flux leakage measurements from each of the plurality of magnetic sensors 110a, 110b, 110c, 110d. In one embodiment, the external magnetic flux leakage measurements received from each magnetic sensor may be pre-processed to generate a DC component of the external magnetic flux leakage measurements, which may be further processed to detect an air gap eccentricity and a severity level of the air gap eccentricity in the rotary machine 100.

[0117] At operation 506 of method 500, an air gap eccentricity condition of the rotating machine is determined based on a moving average value associated with each of the plurality of magnetic sensors. When compared within a series of average values ​​of external leakage flux measurements associated with a magnetic sensor (e.g., magnetic sensor 110a), any deviation of the moving average value beyond a predefined threshold value indicates the presence of air gap eccentricity. Similarly, when compared with a moving average value of a corresponding portion of external leakage flux measurements associated with another magnetic sensor (e.g., magnetic sensor 110b), any deviation of the moving average value indicates air gap eccentricity. Reference has been made to Figure 2 and 4A -4B details determining the type of air gap eccentricity in the rotating machine 100, which is not described again here for the sake of brevity. The type of air gap eccentricity condition and the severity level of the air gap eccentricity condition can be displayed on the output interface (i.e., I / O module 206), or data related to the air gap eccentricity condition in the rotating machine 100 (i.e., the type and severity level of the air gap eccentricity) can also be sent to a remote server using a secure communication channel for visualization and report generation.

[0118] The operations of methods 400, 450 and 500 do not have to be performed in the order presented. In addition, one or more operations may be combined and performed in the form of a single step, or an operation may have multiple sub-steps that may be performed in parallel or sequentially.

[0119] refer to Figure 5 One or more operations of the disclosed methods or flowcharts 400, 450, and 500 may be implemented using software comprising computer executable instructions stored on one or more computer readable media (e.g., non-transitory computer readable media, such as one or more optical disks, volatile memory components (e.g., DRAM or SRAM), or non-volatile memory or storage components (e.g., hard drives or solid-state non-volatile memory components, such as flash memory components)) and executed on a computer (e.g., any suitable computer, such as a laptop, netbook, web book, tablet computing device, smartphone, or other mobile computing device). For example, such software may be executed on a single local computer.

[0120] Various embodiments of the present disclosure provide many advantages. Embodiments of the present disclosure provide a method and system for detecting air gap eccentricity in a rotating machine. More specifically, the system receives external leakage flux measurements only from non-intrusive external sensors that measure leakage flux generated outside the air gap of the rotating machine 100. More specifically, magnetic sensors that have been deployed in the rotating machine 100 for monitoring machine conditions can be used without any special structural changes, which is different from intrusive sensors placed in the air gap 106 of the rotating machine 100. The disclosed method uses signal processing techniques to detect eccentric conditions while distinguishing them from non-eccentric conditions such as rotor short circuits and stator short circuits. In general, these embodiments propose techniques for identifying air gap eccentricity conditions and air gap eccentricity types in the rotating machine 100. In addition, the method is robust and insensitive to rotor and stator short circuits. This insensitivity to rotor and stator short circuits ensures that dynamic eccentricity can be distinguished from rotor short circuits and static eccentricity can be distinguished from stator short circuits. Furthermore, the system can be deployed in existing systems using protection relays or digital solutions when real-time operation is required. In real-time, if the system is deployed in a relay, it can be configured to trip the circuit breaker based on a fault severity level that can be set by the customer. Furthermore, the system can also be deployed in a centralized / cloud application where it will receive external leakage flux measurements at regular intervals and provide information about any developing air gap eccentricity conditions that may lead to a fault and the severity level of the air gap eccentricity at a given time. Furthermore, the severity level of the air gap eccentricity can also be determined, which will help the user / operator to take timely corrective measures before the condition deteriorates. Furthermore, since signal processing techniques are used to analyze the external leakage flux measurements, the amount of computational resources consumed to determine the air gap eccentricity is significantly reduced compared to computationally intensive and complex spectral analysis that consumes a lot of memory and processing resources.

[0121] Those skilled in the art will appreciate that, in general, the terms used herein are generally intended to be "open" terms (e.g., the term "including" should be interpreted as "including but not limited to", the term "having" should be interpreted as "having at least", the term "comprising" should be interpreted as "including but not limited to", etc.). For example, to aid understanding, the detailed description may contain the use of the introductory terms "at least one" and "one or more" to introduce statements. However, the use of such phrases should not be construed as implying that the introduction of a statement by the indefinite article "a" or "an" limits any particular description portion containing such introduced statement to an invention containing only one such statement, even if the statement contains the introductory terms "one or more" or "at least one" and an indefinite article such as "a" or "an" (e.g., "a" and / or "an" should generally be interpreted as meaning "at least one" or "one or more"); the same is true for the use of definite articles used to introduce such statements. In addition, even if a particular portion of an introduced description statement is explicitly recited, those skilled in the art will recognize that such statements should generally be interpreted as referring to at least the recited number (e.g., a simple statement of "two statements" without other modifiers generally means at least two statements or two or more statements).

[0122] Although various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for illustrative purposes only and are not intended to be limiting, with the true scope and spirit being indicated by the following detailed description.

Claims

1. A method for determining an air gap eccentricity condition in a rotating machine (100), the method comprising: Receiving, by a processor (202), external leakage flux measurements of a rotating machine (100) from each of a plurality of magnetic sensors (110a, 110b, 110c, 110d); determining, by the processor (202), a moving average of external leakage flux measurements received from each of the plurality of magnetic sensors (110a, 110b, 110c, 110d); as well as An air gap eccentricity condition of the rotating machine (100) is determined by the processor (202) based on a moving average value associated with each of the plurality of magnetic sensors (110a, 110b, 110c, 110d).

2. The method according to claim 1, wherein: The air gap eccentricity condition is at least one of the following: static eccentricity and dynamic eccentricity.

3. The method according to claim 1, wherein: Determining the air gap eccentricity condition of the rotating machine (100) comprises: determining a maximum moving average and a minimum moving average based on moving averages associated with external leakage flux measurements from at least one of the plurality of magnetic sensors (110a, 110b, 110c, 110d); determining a dynamic index based on the maximum moving average and the minimum moving average; and When the dynamic index is greater than the dynamic eccentricity threshold, the air gap eccentricity condition is determined as dynamic eccentricity.

4. The method according to claim 3, further comprising: A dynamic eccentricity severity level is determined based on the dynamic index.

5. The method according to claim 1, wherein: Determining the air gap eccentricity condition of the rotating machine includes: determining a plurality of magnetic flux density distributions based on a moving average of external leakage flux measurements received from each of the plurality of magnetic sensors (110a, 110b, 110c, 110d); identifying a minimum magnetic flux density distribution among the plurality of magnetic flux density distributions as a first reference magnetic flux density distribution, and identifying a maximum magnetic flux density distribution among the plurality of magnetic flux density distributions as a second reference magnetic flux density distribution; determining a plurality of magnetic flux density distribution distances based on the plurality of magnetic flux density distributions, the first reference magnetic flux density distribution, and the second reference magnetic flux density distribution, wherein each magnetic flux density distribution distance is determined by comparing each of the plurality of magnetic flux density distributions with each of the first reference magnetic flux density distribution and the second reference magnetic flux density distribution; Determine a distribution difference between a current moment and a previous moment for each of the plurality of magnetic flux density distribution distances; determining a static index based on the plurality of magnetic flux density distribution distances and the distribution difference; and When the static index is greater than the static eccentricity threshold, the air gap eccentricity condition is determined as static eccentricity.

6. The method according to claim 5, further comprising: A static eccentricity severity level is determined based on the plurality of magnetic flux density distribution distances.

7. The method according to claim 4 or 6, further comprising: A control signal is generated by the processor (202) based on at least one of the dynamic eccentricity severity level and the static eccentricity severity level for actuating a circuit breaker electrically coupled to the rotating machine (100).

8. The method according to claim 1, further comprising: A notification is generated by a processor (202) based on a determination of an air gap eccentricity condition of the rotating machine (100).

9. A system (150) for determining an air gap eccentricity condition in a rotating machine (100), comprising: a memory (204) configured to store instructions (205); and A processor (202) configured to execute instructions (205) stored in the memory (204), and thereby configured to: Receiving external leakage flux measurements of a rotating machine (100) from a plurality of magnetic sensors (110a, 110b, 110c, 110d); determining a moving average of external leakage flux measurements received from each of the plurality of magnetic sensors (110a, 110b, 110c, 110d); and An air gap eccentricity condition of the rotating machine (100) is determined based on a moving average value associated with each of the plurality of magnetic sensors (110a, 110b, 110c, 110d).

10. The system (150) of claim 9, wherein: The air gap eccentricity condition is at least one of: static eccentricity and dynamic eccentricity.

11. The system (150) of claim 9, wherein: To determine an air gap eccentricity condition of the rotating machine (100), the processor (202) is configured to: determining a maximum moving average and a minimum moving average based on moving averages associated with external leakage flux measurements from at least one of the plurality of magnetic sensors (110a, 110b, 110c, 110d); determining a dynamic index based on the maximum moving average and the minimum moving average; and When the dynamic index is greater than a dynamic eccentricity threshold, the air gap eccentricity condition is determined as dynamic eccentricity.

12. The system (150) of claim 11, wherein: The processor (202) is also configured to: A dynamic eccentricity severity level is determined based on the dynamic index.

13. The system (150) of claim 9, wherein: To determine an air gap eccentricity condition of the rotating machine (100), the processor (202) is configured to: determining a plurality of magnetic flux density distributions based on external leakage flux measurements received from each of the plurality of magnetic sensors (110a, 110b, 110c, 110d); identifying a minimum magnetic flux density distribution among the plurality of magnetic flux density distributions as a first reference magnetic flux density distribution, and identifying a maximum magnetic flux density distribution among the plurality of magnetic flux density distributions as a second reference magnetic flux density distribution; determining a plurality of magnetic flux density distribution distances based on the plurality of magnetic flux density distributions, the first reference magnetic flux density distribution, and the second reference magnetic flux density distribution, wherein each magnetic flux density distribution distance is determined by comparing each magnetic flux density distribution in the plurality of magnetic flux density distributions with each of the first reference magnetic flux density distribution and the second reference magnetic flux density distribution; determining a distribution difference between a current moment and a previous moment for each of the plurality of magnetic flux density distribution distances; determining a static index based on the plurality of magnetic flux density distribution distances and the distribution difference; and When the static index is greater than the static eccentricity threshold, the air gap eccentricity condition is determined as static eccentricity.

14. The system (150) of claim 13, wherein: The processor (202) is also configured to: A static eccentricity severity level is determined based on the plurality of magnetic flux density distribution distances.

15. The system (150) according to claim 12 or 14, wherein: The processor (202) is also configured to: A control signal is generated based on at least one of the dynamic eccentricity severity level and the static eccentricity severity level for actuating a circuit breaker electrically coupled to the rotating machine (100).

16. The system (150) of claim 9, wherein: The processor (202) is also configured to: A notification is generated based on a determination of an air gap eccentricity condition of the rotating machine (100).

Images