DEVICE RELEASEABLY COUPLABLE TO AN ELECTRIC ASSET AND METHOD FOR OBTAINING IDENTIFICATION OF AT LEAST ONE ELECTRIC ASSET AND INFORMATION ABOUT PARTIAL DISCOVERY EXPERIENCED BY AT LEAST ONE ELECTRIC ASSET - Patent application

Abstract

According to an embodiment of the present invention, a device releasably coupleable to an electric asset is provided. The device comprises a sensor configured to detect partial discharge from the electric asset and generate a pulse signal representative of the presence or absence of detected partial discharge, and a time domain based RFID tag electrically coupled to the sensor. The time domain based RFID tag is configured to uniquely provide an ID code representative of the location of the device when coupled to the electric asset. The device is configured to generate a backscatter signal and a pulse signal including the ID code upon interrogation by an external interrogation transmitter. The generated backscatter signal is to be read by an external reader. According to a further embodiment, a method for obtaining an identity of at least one electric asset and information about partial discharge experienced by at least one electric asset is also provided.

Description

[Technical field]

[0001] This application claims the benefit of priority to Singapore Patent Application No. 10202106164Q filed on June 9, 2021, the contents of which are hereby incorporated by reference in their entirety for all purposes.

[0002] Various embodiments relate to a device releasably coupleable to an electric asset and a method for obtaining an identity of at least one electric asset and information about partial discharge experienced by the at least one electric asset. [Background technology]

[0003] Partial discharge (PD) is a localized dielectric breakdown of electrical insulation in electrical assets operating at high voltages, revealing hidden dielectric defects in the insulation. If PD is left undetected, it leads to the degradation of the electrical asset and then to its unexpected breakdown. Therefore, detection of PD is essential to prevent the expected failure of critical electrical assets.

[0004] PDs can be detected by a variety of sensors, such as pulsed current sensors, acoustic sensors, optical sensors, and radio frequency (RF) sensors. For example, pulsed current sensors detect high-frequency spectral components of current during PD events, but the detection capabilities of pulsed current sensors may be affected when there is significant high-frequency PD-irrelevant background noise. Acoustic sensors detect acoustic waves associated with PD, but wave propagation may be affected by the structure of the electrical asset, and detection of acoustic waves may be challenging in urban environments with large acoustic background noise. Optical sensors are highly sensitive and compact in size, but their implementation is intrusive. RF emission sensors detect PDs by capturing and analyzing electromagnetic (EM) waves associated with PDs. RF emission sensors have gained popularity due to their relative ease of implementation and their non-intrusive nature. When an RF receiving antenna is chosen as the sensor for EM waves associated with PDs, the sensor is placed several meters away from the electrical asset in the far-field region of the EM waves. When an RF sensing coil is chosen as the sensor for EM waves, the sensor is mounted on the electrical asset, which is in the near-field region of the EM waves. For PD detection in the far-field region, several receiving antennas placed at different locations are needed so that the PD source localization can be estimated based on the different arrival times of the EM waves at the antennas. Through simulations on an empty volume of about 10 m (length L) x 4 m (width W) x 4 m (height H) based on a total of four antennas, the theoretical PD source detection accuracy is reported to be 39.3 mm, but has not been experimentally proven. In practice, the PD source localization accuracy based on arrival time analysis depends on the number of possible EM wave propagation paths due to reflections in and out of the electrical asset. Also, the PD signal detected by the antenna is in the μV range, which cannot be easily distinguishable when strong EM background noise exists in the environment.

[0005] In situations where more than one electrical asset is employed, identifying the correct electrical asset from which the PD signal originates can be extremely challenging and sometimes impossible.

[0006] RFID is a contactless ID technology that automatically identifies target objects and obtains relevant data by RF signals without manual intervention. Nevertheless, compared to barcodes, the higher manufacturing cost restricts chip-based RFID tags from being widely used. One of the recent advancements in RFID technology is chipless RFID, which refers to RFID tags that do not contain silicon chips. Chipless RFID has lowered the manufacturing cost and has been integrated into pressure, humidity, temperature, gas, and strain sensors for practical applications. With no silicon chip, chipless RFID tags have the innate ability to withstand harsh operating environments.

[0007] A frequency-domain (FD)-based chipless RFID approach has been reported, which detects EM waves through a wideband antenna and modulates the frequency signature with a two-step impedance resonator (SIR). FD-based chipless RFID approaches have shown their capability to facilitate discriminative detection simultaneously, but they require high bandwidth, which increases the reader design cost.

[0008] Therefore, there is a need to provide a device and / or apparatus and method for obtaining identity information of an electrical asset and information about partial discharges experienced by the electrical asset while addressing at least the above-mentioned problems. Summary of the Invention

[0009] According to an embodiment, a device releasably coupleable to an electrical asset is provided. The device may include a sensor configured to detect partial discharge from the electrical asset and generate a pulsed signal representative of the presence or absence of the detected partial discharge, and a time-domain based RFID tag electrically coupled to the sensor, the time-domain based RFID tag configured to uniquely provide an ID code representative of the location of the device when coupled to the electrical asset. The device may be configured to generate a backscatter signal and a pulsed signal including the ID code upon interrogation by an external interrogator, and the generated backscatter signal may be read by an external reader.

[0010] According to an embodiment, an apparatus is provided, which may include at least one device according to various embodiments, each device releasably coupleable to a respective corresponding electric asset, an external interrogation transmitter configured to transmit an interrogation signal to the at least one device to generate a backscatter signal, and an external reader configured to read the backscatter signal to obtain an identity of the corresponding electric asset and information about partial discharges experienced by the corresponding electric asset.

[0011] According to an embodiment, a method for obtaining an identity of at least one electric asset and information about partial discharge experienced by the at least one electric asset is provided, the method including: transmitting an interrogation signal by an external interrogation signal transmitter to at least one device, each device releasably coupled to a respective corresponding electric asset, detecting a partial discharge from the respective corresponding electric asset by each device, generating by each device a backscatter signal including an ID code uniquely representing a location of the device coupled to the respective corresponding electric asset and a pulse signal representative of the presence or absence of a detected partial discharge, and reading by an external reader the backscatter signal to obtain the identity of the respective corresponding electric asset and information about partial discharge experienced by the respective corresponding electric asset.

[0012] In the drawings, like reference characters generally refer to like parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed generally on illustrating the principles of the invention. In the following description, various embodiments of the invention are described with reference to the following drawings, in which: [Brief description of the drawings]

[0013] [Figure 1A] 1 is a schematic diagram of a device releasably coupleable to an electrical asset, according to various embodiments. [Figure 1B] 1B is a schematic diagram of an apparatus including at least one device of FIG. 1A, according to various embodiments. [Figure 1C] 4 is a flow chart illustrating a method for obtaining an identity of at least one electric asset and information about partial discharge experienced by the at least one electric asset, according to various embodiments. [Diagram 2] FIG. 1 is a schematic diagram of an example system architecture for chipless or chipped RFID based remote condition monitoring, according to various embodiments. [Diagram 3]1 is a plot illustrating current-voltage (IV) curves for a state-change component according to one embodiment. [Figure 4] FIG. 1 illustrates an example system overview of a TD-based chipless RFID tag with a sensing coil for PD detection and source identification, in accordance with various embodiments. [Figure 5A] FIG. 1 is a schematic diagram illustrating a proposed prototype of a chipless RFID tag based on the Time Domain Reflectometry (TDR) operating principle using a PD sensor, according to one embodiment. [Figure 5B] FIG. 1 is a schematic diagram illustrating the architecture of a cascaded structure based time domain (TD) chipless RFID tag according to one embodiment. [Figure 5C] FIG. 2 is a schematic diagram illustrating the architecture of a power splitter-based TD chipless RFID tag according to one embodiment. [Figure 6A] 1 is a schematic perspective projection of the final structural dimensions of a zeroth-order resonator (ZOR) antenna, according to one embodiment. [Figure 6B] FIG. 2 is an equivalent circuit diagram of a composite right / left hand transmission line (CRLH TL) in accordance with various embodiments. [Figure 7A] FIG. 2 is an equivalent circuit diagram of a unit cell of a vialess CRLH delay line according to one embodiment. [Figure 7B] FIG. 2 is a schematic perspective view of a unit cell of a CRLH delay line according to one embodiment. [Figure 8] 7C is a plot illustrating the relationship between group delay and frequency of the CRLH delay line of FIG. 7B. [Figure 9A] FIG. 1 is a schematic perspective view of a square split ring resonator (SRR) structure according to one embodiment. [Figure 9B] 1 is an equivalent circuit diagram of an SSR, according to various embodiments. [Figure 10A]FIG. 1 is a schematic perspective view of a complementary split ring resonator (CSRR1) structure with capacitive stubs, according to one embodiment. [Figure 10B] FIG. 1 is a schematic perspective view of a complementary split ring resonator (CSRR2) structure with inductive microstrip lines according to one embodiment. [Figure 10C] FIG. 1C is an equivalent circuit diagram of the complementary split-ring resonator of FIG. 10A or FIG. 10B. [Figure 11] 11 is a plot illustrating simulated phase shift versus time for four modulation sections with delay lines in accordance with various embodiments. [Figure 12A] FIG. 1 is a schematic diagram of a design employing a reconfigurable stub line with two apparent delay sections and a phase shifter according to one embodiment. [Figure 12B] FIG. 12B is an enlarged top view of one delay section of FIG. 12A. [Figure 12C] FIG. 12B is a corresponding bottom view of one delay section of FIG. 12A. [Figure 12D] FIG. 12C is a cut-out perspective view of the power splitter with unadjusted reconfigurable stub lines of FIG. 12B. [Figure 12E] FIG. 12C is a cutaway top view of the power splitter with untuned reconfigurable stub lines of FIG. 12B. [Figure 12F] FIG. 12C is a corresponding bottom view of the power splitter with untuned reconfigurable stub lines of FIG. 12B. [Figure 13] FIG. 13 is a cutaway top view of a power splitter with reconfigurable stub lines soldered to effect phase according to one embodiment with the phase shifter disabled. [Figure 14] FIG. 13 is a cutaway top view of a power splitter with reconfigurable stub lines soldered to effect phase, according to one embodiment, with a phase shifter enabled, having additional conductors soldered. [Figure 15]FIG. 1 is a diagram of a time domain signal of a TD chipless RFID tag with 16PSK modulation, with an inset being a polar diagram, according to one embodiment. [Figure 16A] 1 is a polar diagram illustrating the phase shift of a reflector without a phase shifter, according to one embodiment. [Figure 16B] 4 is a polar diagram illustrating the phase shift of a reflector with a phase shifter according to one embodiment. [Figure 17] 1 is a photograph of an early design coil prototype according to one embodiment. [Figure 18] 1 is a photograph of a multi-band coil prototype according to one embodiment. [Figure 19] Figures 17 and 18 are comparative plots depicting the power spectra of PD signals captured by two different sensing coil designs. [Figure 20] Figures 17 and 18 are comparative plots depicting the time-domain PD signals captured by two different sensing coil designs. [Figure 21] 1 is a photograph of a fabricated chipless RFID tag with a diode-integrated sensing coil set up for experimental validation according to one embodiment. [Figure 22A] FIG. 1 is a schematic perspective view of a model of a transducer with a bushing having a housing having a metallic outer surface and an insulating inner surface, a metal shaft disposed through a hole in one surface of the housing, and an annular ceramic member surrounding the shaft, according to one embodiment. [Figure 22B] FIG. 22B is a simulation of the electric field distribution using the model of FIG. 22A without the sensing coil. [Figure 22C] FIG. 22B is a simulation of the electric field distribution using the model of FIG. 22A with a sensing coil. [Diagram 23] FIG. 2 is an equivalent circuit diagram of a diode-equipped sensing coil, according to one embodiment. [Figure 24A] FIG. 2 is a block diagram of a measurement setup of a PD detection system according to one embodiment. [Figure 24B]1 is a photograph of an actual measurement setup of a PD detection system according to one embodiment. [Diagram 25] 24A and 24B , (b) a plot illustrating the relationship between coil voltage and time, (c) a plot illustrating the relationship between voltage ratio and time, and (d) a plot illustrating the relationship between phase difference and time. [Figure 26] 1 is a plot illustrating the phase change of a signal received by a reader during a polling cycle of four chipless RFID tags equipped with PD sensors in accordance with various embodiments. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The following detailed description refers to the accompanying drawings, which show, by way of illustration, specific details and embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. Other embodiments may be utilized, and structural, logical, and electrical changes may be made without departing from the scope of the invention. The various embodiments are not necessarily mutually exclusive, as some embodiments may be combined with one or more other embodiments to form new embodiments.

[0015] An embodiment described in the context of one of a method or device is equally valid for the other method or device, and similarly, an embodiment described in the context of a method is equally valid for the device, and vice versa.

[0016] Features described in the context of an embodiment may also be applicable to the same or similar features in other embodiments. Features described in the context of an embodiment may also be applicable to other embodiments, even if not explicitly described in these other embodiments. Furthermore, additions and / or combinations and / or alternatives to features described in the context of an embodiment may also be applicable to the same or similar features in other embodiments.

[0017] In the context of the various embodiments, the articles "a," "an," and "the" as used in connection with features or elements include a reference to one or more of the features or elements.

[0018] In the context of various embodiments, the phrase "at least substantially" can include "exactly" and reasonable variations.

[0019] In the context of the various examples, the terms "about" or "approximately" as used with numerical values ​​encompass the exact value and reasonable variations.

[0020] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0021] As used herein, a phrase of the form "at least one of A or B" can include A or B, or both A and B. Similarly, a phrase of the form "at least one of A or B or C," or a phrase including additional listed items, can include any and all combinations of one or more of the associated listed items.

[0022] As used herein, the phrase "configured to" can mean "constructed to" or "arranged to."

[0023] Various embodiments provide an RFID-based detection system for partial discharge (PD) detection and identification. For example, the system may be a chipless RFID-based detection system. Various embodiments may also provide a vialess passive metamaterial (MTM)-based quadrature phase shift keyed (QPSK) modulated chipless radio frequency identification (RFID) tag integrated with a PD sensor for PD detection and identification. Individual tags with sensors may be mounted on specific electrical assets to be monitored. When interrogated by an external reader at 2.4 GHz, the tags respond with a signal containing the ID information and status of the PD sensor. Any detected PD event may be traced back to the respective electrical asset generating the PD emission after time domain (TD) analysis, which allows for prompting corrective actions before further degradation and premature failure of the asset.

[0024] FIG 1A illustrates a schematic diagram of a device 100 releasably coupleable to an electrical asset, according to various embodiments. The device 100 may include a sensor 102 configured to detect partial discharge from an electrical asset (not shown in FIG 1A) and generate a pulsed signal representative of the presence or absence of a detected partial discharge, and a time-domain based RFID tag 104 electrically coupled to the sensor 102 (as represented by line 106), the time-domain based RFID tag 104 configured to uniquely provide an ID code representative of the location of the device 100 when coupled to the electrical asset. The device 100 may be configured to generate a backscatter signal and a pulsed signal including the ID code upon interrogation by an external interrogation transmitter (not shown in FIG 1A), the generated backscatter signal to be read by an external reader (not shown in FIG 1A).

[0025] In the context of various embodiments, a topology "representative of" can interchangeably refer to representing, relating to, or capable of indicating.

[0026] The phrase "electrically coupled" may mean directly or indirectly connected to or provided as an electrical connection.

[0027] The phrase "ID code" refers to an identity code or identification code.

[0028] In other words, PD detection in the near-field region is the focus here. The sensor 102 may be in the preferred form of an RF sensing coil mounted on the exterior shelf of the electrical asset. EM waves associated with PD generated within a power transformer may be detected by a coil mounted on the exterior metal surface of the power transformer. The coil installation is usually advised by the asset owner who has prior knowledge of the most probable PD source location. The sensing coil may also be designed based on the size of the available area and the required detection sensitivity. For example, a 55 cm x 80 cm coil may be mounted on the transducer surface, which may be approximately 15 cm away from the transducer windings to detect PD caused by degraded winding insulation, and a 50-turn 32 cm narrow coil may be placed in the gap of the steel frame surface of the motor to detect PD due to degraded stator winding insulation. Since the EM waves are in the near-field region, the signal detected by the coil is in the range of several hundred mV, improving the signal-to-noise ratio of the PD detection. Furthermore, tags may be integrated into the sensing coil so that each electrical asset has a unique identity (ID) to trace the defective asset in case of a PD event. By connecting the open-ended microstrip line output of each RFID tag to a sensing coil and mounting the sensing coil directly at the appropriate location on the electrical asset, the sensing coil helps to identify the defective asset with high certainty.

[0029] To address the problems presented by the frequency domain (FD)-based chipless RFID approach, a time domain (TD)-based RFID tag (e.g., 104 in FIG. 1A) with a sensing coil is proposed. The TD-based RFID tag may be chipped (i.e., chip-based) or chipless. In one example of a specific use case of the TD-based chipless RFID tag with a sensing coil, it may provide additional advantages of being battery-less since the device receives its power wirelessly by the interrogator signal, good PD detection reliability due to near-field sensing, and the ability to distinguish PD from different assets for defective asset identification.

[0030] Unlike physical parameters such as pressure, humidity, temperature, gas, or strain, PD is a transient event. Each PD event usually lasts for only a few hundred nanoseconds, and the signal level is weak and prone to decay over time, unlike physical parameters such as pressure, humidity, temperature, gas, or strain, which do not change significantly in such a short period of time. Therefore, capturing PD events requires the sensor to have high sensitivity, fast response, and a hold time large enough for the RFID tag to transmit the information to the reader. At the same time, the RFID read cycle is required to be short enough to ensure that the signal can be captured reliably. Technical and collaborative considerations of the design of both the sensor (e.g., 102) and the tag (e.g., 104) are required in realizing the device 100. In other words, the design considerations of the sensor (e.g., 102) and the tag (e.g., 104) are not independently implementable as two separate units, and therefore, they are simply integrated together. Therefore, the device 100 cannot be considered as a mere plug, but acts like an inductive substitute from existing parameter sensors with RFID tags. Although there may be existing dedicated PD sensors in the current market for measuring PD waveforms, such existing sensors are relatively expensive and are mainly used for scheduled maintenance checks at substations, rather than large-scale deployment for continuous PD monitoring. The proposed device 100 is designed to detect the presence of PD events without capturing detailed waveforms, eliminates complex PD waveform receiving circuitry, and can also be produced at a relatively low cost, making the device 100 an ideal choice for large-scale PD monitoring.

[0031] In one example, the generated pulse signal including a phase change can indicate that there is a detected partial discharge from the electrical asset, and the generated pulse signal not including a phase change can indicate that there is no detected partial discharge from the electrical asset. Conversely, the generated pulse signal including a phase change can indicate that there is no detected partial discharge from the electrical asset, and the generated pulse signal not including a phase change can indicate that there is a detected partial discharge from the electrical asset.

[0032] In various embodiments, the sensor 102 may comprise at least one sensing coil for detecting partial discharge and at least one state-change component connected in parallel with the at least one sensing coil and operable to generate a pulsed signal. The at least one state-change component may comprise a nonlinear component, such as, but not limited to, a fast response diode, a detector diode, a PN junction diode, a Schottky barrier diode, a varactor / varicap diode, a bipolar junction transistor, a field effect transistor, or a memristor.

[0033] The sensor 102 may include an additional sensing coil electrically coupled in series with the at least one sensing coil. The at least one sensing coil may be configured to operate at a first resonant frequency and the additional sensing coil may be configured to operate at a second resonant frequency, the first resonant frequency being different from the second resonant frequency. In other words, the additional sensing coil and the at least one sensing coil may operate at different resonant frequencies.

[0034] The at least one sensing coil can include multiple sensing coils configured to operate at different resonant frequencies, where each resonant frequency is separated from the others, and to provide an extended bandwidth to the sensor 102, where the extended bandwidth depends on the spread of the different resonant frequencies.

[0035] In various embodiments, the time-domain based RFID tag 104 may include a delay line including one or more discontinuities, each of which is configured to provide one or more unique codes, and the unique codes from the one or more discontinuities are used as the ID code. In some instances, each discontinuity may include one of a split ring resonator, or a complementary split ring resonator, or a combination of a split ring resonator and a complementary split ring resonator. In other instances, the discontinuity may include one of a reconfigurable stub line, or a reconfigurable stub line and a phase shifter. In the case of two or more discontinuities, each discontinuity may be spaced apart from one another.

[0036] The delay line may be a composite right / left handed transmission line.

[0037] The time-domain based RFID tag 104 may further comprise a power divider coupled to the discontinuities and arranged along the delay line in such a manner that the discontinuities may be indirectly coupled to the delay line through the power divider. The power divider may be configured to at least reduce excess signal reflections from the discontinuities, thereby ensuring that only one signal reflection is performed by the discontinuities.

[0038] The distal end of the delay line may be coupled to the sensor 102, allowing a time lag to be provided between the ID code and the pulse signal.

[0039] The time-domain based RFID tag 104 may further include an antenna coupled to a proximal end of the delay line, the proximal end being opposite the distal end. The antenna may be configured to receive an interrogation signal from an external interrogation transmitter. In this example, the antenna may be integrated within the time-domain based RFID tag 104.

[0040] In another example, the device 100 can include an antenna coupled in series with the time domain based RFID tag 104, the antenna configured to receive interrogation signals from an external interrogation transmitter. In this other example, the antenna can be external to the time domain based RFID tag 104.

[0041] In various embodiments, device 100 may further include at least one parameter sensor, each electrically coupled to the time domain based RFID tag, which may be described similarly to the time domain based RFID tag 104. The at least one parameter sensor may be configured to detect at least one parameter experienced by the electrical asset to determine an anomalous change in the at least one parameter.

[0042] The time domain based RFID tag 104 may be a time domain based chipped RFID tag or a time domain based chipless RFID tag. Each time domain based RFID tag electrically coupled to at least one parameter sensor may be a time domain based chipped RFID tag or a time domain based chipless RFID tag.

[0043] In one embodiment, the time domain based RFID tag 104 is a time domain chipped based RFID tag, and the device 100 may further comprise at least one parameter sensor electrically coupled to the time domain based chipped RFID tag 104. The at least one parameter sensor may be configured to detect at least one parameter experienced by the electrical asset to determine an anomalous change in the at least one parameter. In other words, multiple sensors, including the sensor 102, may be electrically coupled to a single time domain chipped based RFID tag.

[0044] In various embodiments, the at least one parameter sensor may comprise at least one of a temperature sensor, a humidity sensor, a vibration sensor, or a strain sensor.

[0045] 1B shows a schematic diagram of an apparatus 120 according to various embodiments. The apparatus 120 may comprise at least one device 100, each device 100 releasably coupleable to a respective corresponding electric asset (not shown in FIG. 1B), according to various embodiments, an external interrogation transmitter 122 configured to transmit an interrogation signal to the at least one device 100 to generate a backscatter signal, and an external reader 124 configured to read the backscatter signal to obtain an identity of the corresponding electric asset and information about partial discharge experienced by the corresponding electric asset. The at least one device 100 may be in communication with the external interrogation transmitter 122 and the external reader 124 as represented by respective lines 126, 128.

[0046] Apparatus 120 may include elements or components that are the same as or similar to those of device 100 of FIG. 1A, and thus the similar elements may be as described in the context of device 100 of FIG. 1A, and thus the corresponding description may be omitted here.

[0047] In various embodiments, the external interrogation transmitter 122 and the external reader 124 may be integrated into a single external interrogation transmitter and reader.

[0048] An exemplary system architecture for chipless or chipped RFID-based remote conditional monitoring, as seen in schematic diagram 201 of Fig. 2, may include an apparatus 120 according to various embodiments. In Fig. 2, there are m remote sites, denoted as remote site #1, remote site #2, ..., remote site #m, and each remote site may have n devices under test, such as DUTs 211a, 211b, 211m (e.g., DUT11, DUT12, ..., DUT1n at remote site #1, DUT21, DUT22, ..., DUT2n at remote site #2, and DUTm1, DUTm2, ..., DUTmn at remote site #m). Each DUT 211a, 211b, 211m may be an electrical asset with a device (e.g., 100) mounted thereon. Each device includes an RFID detection tag 104a, 104b, ..., 104m (described in a similar context to the time-domain-based RFID tag 104 of FIG. 1A). The RFID detection tags 104a, 104b, ..., 104m may be interrogated by a respective RFID interrogation transmitter 122a, 122b, ..., 122m (described in a similar context to the external interrogation transmitter 122 of FIG. 1B) at or near each remote site. Each RFID interrogation transmitter 122a, 122b, ..., 122m may also be integrated into a reader (described in a similar context to the external reader 124 of FIG. 1B) and is in communication with a TV white space transmitter-receiver (TVWS Tx / Rx) 207a, 207b, ..., 207m coupled to an antenna 209a, 209b, ..., 209m. Each remote site may be located within a radius of approximately 5 km from a remote TVWS Tx / Rx 207c equipped with an antenna 209c for transmitting signals to and from the remote site. The remote TVWS Tx / Rx 207c may be in communication with a remote monitoring center 203 via any nearest available internet access 205.With such a system architecture, the remote monitoring center 203 can be provided as a centralized unit for monitoring whether a partial discharge is being experienced by any of the DUTs 211a, 211b, 211m and, if so, from which DUTs 211a, 211b, 211m.

[0049] FIG. 1C shows a flow chart illustrating a method 140 for obtaining identification information of at least one electric asset and information about partial discharge experienced by at least one electric asset, according to various embodiments. In FIG. 1C, in step 142, an interrogation signal may be transmitted by an external interrogation signal transmitter (e.g., 122 in FIG. 1B) to at least one device (e.g., 100), each device 100 being releasably coupled to each corresponding electric asset. In step 144, a partial discharge from the corresponding electric asset may be detected by each device 100. In step 146, a backscatter signal may be generated by each device 100. The backscatter signal may include an ID code that uniquely represents the location of the device 100 coupled to the corresponding electric asset, and a pulse signal that represents the presence or absence of a detected partial discharge. In step 148, the backscatter signal may be read by an external reader (e.g., 124 in FIG. 1B) to obtain identification information of the corresponding electric asset and information about partial discharge experienced by the corresponding electric asset.

[0050] Method 120 may include elements or components that are the same as or similar to those of device 100 of FIG. 1A or apparatus 120 of FIG. 1B, and therefore are assigned the same numbers, and the similar elements may be as described in the context of device 100 of FIG. 1A or apparatus 120 of FIG. 1B, and therefore corresponding descriptions are omitted here.

[0051] In step 146 of generating the backscattered signal, the state-change component of the device 100 may remain in a first state when substantially no partial discharge is detected such that the phase of the pulse signal remains unchanged, and the state-change component may be changed to a second state by an induced pulse voltage of a detected partial discharge to result in a phase change of the pulse signal.

[0052] A manner of detecting the induced pulse voltage may be by detecting a change in resistance R of the state-change component.

[0053] A state-change component (e.g., a diode) may have a current-voltage (IV) curve 301, as shown in FIG. 3. Typically, the voltage required to turn on a diode is called the forward voltage, which may be referred to interchangeably as the cut-in voltage or the on voltage. When the positive voltage across the diode is greater than or equal to the threshold forward voltage, the diode begins to exhibit nonlinear characteristics and may result in an impedance change. In the reverse direction, there is a threshold reverse voltage as well. When the negative voltage across the diode is greater than or equal to the threshold reverse voltage, the diode begins to exhibit nonlinear characteristics and may result in an impedance change as well. Thus, the IV curve 301 may be separated into three parts based on the threshold forward voltage and threshold reverse voltage, resulting in three statuses (Status 1, 2, and 3), as seen in FIG. 3. Status 1 may be considered as no impedance change, since the IV relationship is approximately linear and the impedance change may be negligible. The first state of the state-change component may refer to operation in a status 1 situation. In statuses 2 and 3, the impedance may be considered as a change associated with the diode exhibiting a pronounced non-linear characteristic. The second state of the state-change component may refer to operation in a status 2 situation or a status 3 situation. Alternatively, statuses 2 and 3 may be collectively considered to be an impedance change status, for example when two diodes are connected in parallel. The second state of the state-change component may therefore refer to operation in this impedance change status situation. Although the I-V relationship is still approximately linear in the areas represented by 303, 305 in FIG. 3, operation at these voltages may still be referred to as the second state since the impedance has changed from status 1, and a phase shift compared to status 1 may still be detected.

[0054] Conversely, in an alternative embodiment, the state change components may be arranged or configured in such a manner that the phase of the pulse signal may remain unchanged when there is a detected partial discharge induced pulse voltage (when there is a PD event), and that a phase change of the pulse signal may be effected when there is substantially no partial discharge (when there is no PD event).

[0055] In various embodiments, detecting 144 the partial discharge can include capturing the energy of the partial discharge over an extended bandwidth of a sensor (e.g., 102) of device 100. Sensor 102 can include multiple sensing coils operating at different resonant frequencies, with the extended bandwidth depending on the spread of the different resonant frequencies.

[0056] The device 100 may include a time-domain based RFID tag (e.g., 104) with a delay line, and generating 146 the backscattered signal may include providing one or more unique codes with one or more discontinuities in the delay line and using the unique codes as the ID code. Providing one or more unique codes may include generating one or more unique codes based on phase shift coded modulation. The phase shift coded modulation may be one of 4 phase shift coded modulation or 16 phase shift coded modulation.

[0057] In various embodiments, the method 140 can further include at least reducing excess signal reflections from the discontinuities with a power splitter that may be electrically coupled to the discontinuities and arranged along the delay line in such a manner that the discontinuities are indirectly coupled to the delay line through the power splitter.

[0058] The method 140 may further include receiving the interrogation signal by an antenna of at least one device 100 .

[0059] In various embodiments, the external interrogation transmitter 122 and the external reader 124 may be integrated into a single external interrogation transmitter and reader.

[0060] The method 140 may further include detecting, by at least one parameter sensor of each device 100, at least one parameter experienced by the corresponding electrical asset to determine an abnormal change in the at least one parameter. Each of the at least one parameter sensor may be electrically coupled to a time domain based RFID tag (described in a similar context to the time domain based RFID tag 104 of FIG. 1A). In one instance, the time domain based RFID tag may be a time domain based chipless RFID tag.

[0061] In another example, the time domain based RFID tag may be a time domain chipped based RFID tag, and the method 140 may further include detecting, with at least one parameter sensor of each device 100, at least one parameter experienced by the corresponding electrical asset to determine an anomalous change in the at least one parameter. The at least one parameter sensor may be electrically coupled to the time domain based chipped RFID tag.

[0062] Although the methods described above are illustrated and described as a series of steps or events, it will be understood that any order of such steps or events should not be construed in a limiting sense. For example, some steps may occur in a different order and / or simultaneously with other steps or events apart from those illustrated and / or described herein. Moreover, not all illustrated steps may be required to implement one or more aspects or embodiments described herein. Also, one or more of the steps depicted herein may be performed in one or more separate acts and / or phases.

[0063] Examples of device 100 and method 140 are described in further detail below, and more particularly in the context of the design of chipless RFID tags with sensing coils for PD detection and identification, and the performance of pre-fabricated tags with sensors.

[0064] design A. System Overview Fig. 4 shows an example system overview 401 of a TD-based chipless RFID tag with a sensing coil for PD detection and source identification. In Fig. 4, several chipless RFID tags with an interrogation transmitter and reader 424 and a sensor 400 are provided. Each tag with a sensor is mounted on an electrical asset 411a, 411b, 411c. The interrogation transmitter 424 periodically transmits a pulse signal 413 to all tags, and the response of the pulse signal 413 is received by the reader 424. The distinct ID codes 415a, 415b, 415c and the detected PD data 417a, 417b, 417c associated with the assets 411a, 411b, 411c are included in the signal received by the reader 424 and processed through a host computer, which may be connected via the Internet for remote access (not shown in Fig. 4). When a PD event 419 occurs at a particular asset 411 c , the detected PD signal 417 c and its corresponding ID code 415 c are detected by the reader 424 .

[0065] System overview 401 may include elements or components that are the same or similar to those of device 100 of FIG. 1A and apparatus 120 of FIG. 1B, and thus are assigned the same final numerals, and the similar elements may be as described in the context of device 100 of FIG. 1A and apparatus 120 of FIG. 1B.

[0066] B. Chipless RFID Tag Architecture FIG. 5A shows a schematic diagram illustrating a proposed prototype 500 of a chipless RFID tag 504 based on the time domain reflectometry (TDR) working principle with a PD sensor 502. The prototype 500 may include elements or components that are the same or similar to those of the device 100 of FIG. 1A, and therefore are assigned the same last numerals, and similar elements may be as described in the context of the device 100 of FIG. 1A. The chipless RFID tag 504 has three main components. The first component is an antenna 518 for communication with an interrogation transmitter (e.g., 122 in FIG. 1B) and a reader (e.g., 124 in FIG. 1B), which are not shown in FIG. 5. The second component is a delay line ρ to ensure a sufficient time interval between the transmission signal 513 from the interrogation transmitter and the backscattered signal 516 received by the reader, which may be realized by a composite right-handed / left-handed (CRLH) transmission line (TL). The third component is a discontinuity 514 that provides an abrupt phase change to be used as unique ID information, which may be realized using a split ring resonator (SRR) or a complementary split ring resonator (CSRR). Depending on the number of unique IDs required, different discontinuities may be designed to provide different phase changes. The tag 504 is connected to a PD sensor 502, which includes an RF coil 523 shunted with a diode 525 to detect PD events 519. By way of example, the prototype 501 presented here has four different discontinuities to provide four unique IDs in the form of quadrature phase shift keying (QPSK) modulation.

[0067] In another example, the chipless RFID tag 504 may be provided in the form of a cascaded architecture based TD chipless RFID tag 504a, whose architecture 500a is illustrated in FIG. 5B. The design includes cascaded discontinuities 514a, 514b, ..., 514N (i.e., serially arranged reflectors, each spaced θ apart from an adjacent reflector) and delay lines or delay sections ρ1, ρ2, ..., ρ2, which deliver successive reflected signals 527 as a time domain (TD) response (e.g., backscattered signal 516) of one interrogation 513. N Nevertheless, each reflector 514a, 514b, ..., 514N tends to reflect any signal, including the signal reflected by the backstage reflector, resulting in excessive reflected waves 529, as shown in Figure 5B. This weakens the response signal (e.g., backscattered signal 516) due to higher power consumption and waveform overlap.

[0068] To address this limitation, as shown in Fig. 5C illustrating a schematic diagram of the architecture 500b of a power splitter-based TD chipless RFID tag 504b, power splitters 531a, 531b, ..., 531N may be introduced that can couple a defined amount of signal power in the transmission line to a port that allows the signal to be used in another circuit. By doing so, excessive reflections (e.g. 529 as seen in Fig. 5B) may be eliminated or at least significantly reduced by breaking up the direct cascade of reflectors 514a, 514b, ..., 514N with delay lines or delay sections ρ1, ρ2, ..., ρN and ensuring that only one reflection 527 is performed by each reflector 514a, 514b, ..., 514N.

[0069] C. Antenna The antenna is designed based on a vialess CRLH zeroth order resonator (ZOR) operating at 2.4 GHz. The basic principle is to short one end of a CRLH transmission line (TL) to realize a ZOR resonator radiating in a broadside pattern. Taking into account the operating frequency, the equivalent circuit and initial structure size are estimated and further fine tuning is performed using an EM solver (CST EM studio) to obtain the final structure size. Figure 6A shows the overall size of 35.75 mm (W sub )×21.00mm(L sub 6A shows a schematic perspective projection 601a of the final structural dimensions of the ZOR antenna with a diameter of 0.01 mm and a board thickness of d=0.8128 mm. The circular segments with the meander paths and comb-like interlaced structures are on the top layer / surface of the board (of the PCB), while the dark areas in FIG. 6A are on the projected bottom (or underlying) layer / surface visible at the top. The board material is Rogers RO4003 (relative dielectric constant εr=3.38). The various dimensions of the antenna components are given in Table 1.

[0070] [Table 1]

[0071] FIG. 6B shows an equivalent circuit 601b of the CRLH TL. The left-handed capacitance C L and inductance L L are realized by the interdigital structure and the meander structure, respectively. The microstrip structure has a right-handed capacitance C R and inductance L R The traditional grounding via hole is now replaced by a large area fan patch that provides a capacitance C G To achieve an omnidirectional radiation pattern, a slot in the antenna ground plane is added. The two-port impedance and conductance parameters Z of the structure at the operating frequency are ij and Y ij(i, j = 1, 2) are obtained from full-wave simulations, and their equivalent capacitances and inductances are calculated using equations (1)-(5), where A is the area of ​​the grounding capacitance patch and d is the thickness of the substrate.

[0072]

number

number

[0073] Through equations (1) to (5), L R =5.305nH, C R =2.122pF, L L =1.1937nH,C L = 0.8292 pF, and C G = 3.7 pF. The antenna has an efficiency of -0.287 dB and a gain of 2 dBi at 2.4 GHz. The proposed design achieves a 25.6% reduction in size compared to the conventional design.

[0074] D. Delay line The time delay provided by the CRLH TL operating in the left-handed (LH) domain is longer than that provided by a conventional right-handed (RH) domain TL. For the ID code and PD sensor state to be distinguished, a time interval of at least 3 ns between the two is required. Therefore, the CRLH TL operating in the LH domain at 2.4 GHz is designed with three vialess CRLH unit cells to achieve the required time delay with the minimum size. The equivalent circuit 701a of the unit cell of the vialess CRLH delay line is shown in FIG. 7A. Similarly, the final values ​​of inductance and capacitance, respectively, may be calculated using equations (1)-(4) based on the unit cell structure dimensions given in Table 2 below.

[0075] [Table 2]

[0076] FIG. 7B shows a schematic perspective view 701b of a unit cell of a CRLH delay line according to one embodiment. The final delay line may be realized with three unit cells, each of which provides a time delay of 1.2 ns at 2.4 GHz. The proposed design reduced the size of the final delay line by 33.3% compared to the conventional TL design. The simulated time delay 803 and the measured time delay 805 versus frequency are shown in plot 801 of FIG. 8 illustrating the relationship between group delay and frequency of the CRLH delay line of FIG. 7B. The measurement results showed an upward shift of 0.15 GHz compared to the simulated results, which is about 6.25% error that may be contributed by fabrication tolerances. The measured resonant frequency is 2.55 GHz, and a time delay of 3.67 ns is achieved.

[0077] E. Discontinuities for phase changes To provide four ID codes for four tags, four phase modulation sections with unique reflection coefficients are designed using split ring resonators (SRRs) and complementary split ring resonators (CSRRs). The SRR is essentially a structure consisting of a pair of concentric ring conductors etched on a dielectric substrate with slots etched on both sides. The CSRR is a double structure of SRRs with a pair of concentric split ring slots etched on the ground plane. The equivalent circuit of the CSRR is roughly equivalent to shifting the components of the double SRR equivalent circuit from series to parallel and leaving the values ​​unchanged. The SRR and CSRR structures can provide the effective LH region required for the totally different and abrupt phase changes. For a given structure size, the range of resonant frequencies as well as the impedance of the resonant circuits of the SRRs and CSRRs are rather limited. If all four discontinuities were simply realized by SRRs or CSRRs, the size difference of the four sections could make it challenging to achieve compactness.

[0078] Both SRR and CSRR structures are used to provide four distinct phases in a compact size, and an EM solver is used to estimate and fine-tune the initial dimensions of the rings. The SRR structure 901a and its equivalent circuit 901b are shown in Figures 9A and 9B, respectively. As can be seen in Figure 9A, the SRR 901a has L ground is about 20.40 mm, and W ground A ground plane (dark rectangular area) is provided having a thickness of about 4.08 mm. Although the SRR structure 901a is shown as being rectangular in shape, the structure may also have other shapes.

[0079] The CSRR is a dual structure of SRR, essentially consisting of a pair of concentric ring gaps etched on the ground plane, except for the small segment conductors on either side. Two CSRRs with different structures 1001a, 1001b to provide -45° and 45° phase shift are shown in Figure 10A and 10B respectively, and their equivalent circuit 1001c is shown in Figure 10C. Table 3 shows the dimensions of the CSRR with capacitive stub (CSRR1). The CSRR is provided on the ground plane on the top side of the substrate, while the capacitive stub is provided on the bottom side of the substrate, projected on the top as seen in Figure 10A.

[0080] [Table 3]

[0081] Table 4 shows the dimensions of the CSRR with the inductive microstrip line (CSRR2). The CSRR is provided on the ground plane on the top side of the board, while the inductive microstrip line is provided on the bottom side of the board and projected on top as can be seen in Figure 10B.

[0082] [Table 4]

[0083] For QPSK modulation, four phase shifts, namely 135°, −135°, −45°, and 45°, are designed using two SRRs and two CSRRs with the dimensions given in Table 5.

[0084] [Table 5]

[0085] With the designed SRRs and CSRRs, the four tags can provide four completely different phase changes to the QPSK modulation: 135°, -135°, -45°, and 45°. The respective values ​​of the circuit elements of the two SRRs and two CSRRs are determined and listed in Table 6.

[0086] [Table 6]

[0087] The simulation results of the signal phase from 0 ns to 10 ns for the four-phase modulation section with CRLH delay lines are shown in plot 1101 of Figure 11. The simulated phase changes of SRR1 1107, SRR2 1105, CSRR1 1109, and CSRR2 1103 are 136.26°, -123.5°, 43.2°, and -46.7°, respectively, which actually result in four quite different phase changes.

[0088] The above discussion focuses on four different open-ring resonators deployed to produce four phase shifts as four symbols to achieve quadrature phase shift coding (QPSK) giving four unique IDs, which may be rather limited for large-scale practical applications. This may also not be easily modifiable as soon as the tag is fabricated on a printed circuit board (PCB). Furthermore, the reflection phase of the resonators may be very sensitive to size, which may require several design iterations to fine-tune the reflection phase.

[0089] Alternatively, a reconfigurable chipless RFID tag design may be considered to increase the number of unique IDs. More specifically, the design employs a reconfigurable stub line 1203 and a phase shifter 1205, as shown in schematic diagram 1201 of Figure 12A. In Figure 12A, a power splitter 1231 is employed.

[0090] 12B and 12C show the enlarged top view and corresponding bottom view of the area 1209 of FIG. 12A, respectively, which provides the structure of the power splitter-based chipless RFID tag with unadjusted reconfigurable stub line reflector fabricated on the substrate. The "upper right corner" designation in FIG. 12B marks the same corner when viewed from the bottom of FIG. 12C. The power splitter 1231, the phase shifter 1205, and the reconfigurable stub line 1203 are provided on the top side of the substrate (of the PCB). The phase shifter 1205 is mounted to the CSRR 1211, which is provided on the bottom side (or underside) of the substrate. In other words, the location of the CSRR 1211 is aligned (or overlaps) with the location of the phase shifter 1205. For a clearer view, Figures 12D, 12E, and 12F show a cut-out perspective view, a cut-out top view, and a corresponding bottom view, respectively, of area 1213 of Figures 12B and 12C.

[0091] FIG. 13 shows a cutaway top view (similar to 1213 in FIG. 12E) of a power splitter with reconfigurable stub wires soldered to 1303 to provide phase in one configuration 1213a, where the phase shifter represented by the dotted square 1301 is disabled.

[0092] FIG. 14 shows a cutaway top view (similar to 1213 in FIG. 12E) of a power splitter with reconfigurable stub wires soldered to 1303 to provide a phase according to another configuration 1213b, where the phase shifter represented by the dotted square 1401 is enabled by having an additional conductor with a dotted square 1401 soldered to 1303.

[0093] With this reconfigurable design, 16 symbols can be realized with 16-phase shift coding (16PSK) modulation, as shown in representation 1501 of Figure 15. Figure 15 shows the time domain signal of a TD chipless RFID tag with 16PSK modulation and its insert 1503, which is a polar diagram. Thus, the number of unique IDs has increased from 4 (e.g., for the initial designs in Figures 9A, 10A, and 10B) to 16 (e.g., for the reconfigurable design in Figure 12A).

[0094] The reconfigurable stub line includes several segments. By connecting different segments together (e.g., by soldering), the stub line can have different phase shifts of the reflected signal, as shown in the polar diagram 1601a of FIG. 16A, which depicts the phase shifts of the reflector without a phase shifter (1603, 1605, 1607, 1609, 1611, 1613, 1615). By using a 90-degree phase shifter, the stub line brings about additional phase changes, as shown in the polar diagram 1601b of FIG. 16B, which depicts the phase shifts of the reflector with a phase shifter (1621, 1623, 1625, 1627, 1629, 1631, 1633, 1635, 1637). Thus, by using only two reconfigurable structures, a total of 16 phases of the reflected signal are achieved. At the same time, the labels are modifiable to specific degrees.

[0095] The discontinuities described in this section E may include elements or components that are the same as or similar to those of device 100 of FIG. 1A, and thus the similar elements may be as described in the context of device 100 of FIG. 1A.

[0096] F.PD Sensor An initial coil design is shown in photograph 1701 of Figure 17, which has only a single coil with one resonant frequency and therefore limited bandwidth. Since the electromagnetic emissions associated with partial discharge (PD) are broadband in nature, the narrow bandwidth captures only a partial energy of the PD signal.

[0097] To address this limitation for enhanced PD detection sensitivity, a multi-band coil as shown in photo 1801 of FIG. 18 is designed to widen the bandwidth of the detection coil. The multi-band coil includes four coils operating at different decoupled resonant frequencies. This design extends the overall PD detection bandwidth so that the captured energy of the PD signal is higher, which translates into better detection sensitivity. The coils may be of different shapes and sizes.

[0098] 19 shows a comparative plot 1901 depicting the power spectrum of the PD signal captured by two different sensing coil designs, where the multi-band sensing coil 1903 exhibits resonant frequencies of 6.5 MHz, 10.8 MHz, 14.9 MHz, and 21.3 MHz. Compared to the initial design sensing coil 1905, the power spectrum captured by the multi-band sensing coil 1903 is much higher, resulting in a 2.5 times larger PD signal waveform in the time domain, as observed in the comparative plot 2001 of FIG. 20 depicting the time domain PD signal captured by the two different sensing coil designs 1903, 1905.

[0099] Each of the two different sensing coil designs 1903, 1905 may be described in the analogous context of the sensor 102 of FIG. 1A.

[0100] Chipless RFID tag integrated into PD sensor Based on the aforementioned designs of the ZOR antenna, delay line, and discontinuities in sections C, D, and E above, respectively, the final chipless RFID tag may be fabricated with an overall size of 69 mm (L) x 40 mm (W). The final chipless RFID tag may be described in a similar context to the time-domain based RFID tag 104 of FIG. 1A. Finally, the PD sensor consists of an RF sensing coil and a detector diode is connected at the end of the tag for PD detection. The PD sensor may be described in a similar context to the sensor 102 of FIG. 1A. The coil may be designed with an optimal sensing distance of 10 cm to 20 cm, and is a 10-turn coil with a size of 35 mm x 35 mm and a thickness of 0.52 mm. A Schottky diode with a power-on voltage of 520 mV is in parallel with the coil to provide an impedance change in the event of a PD event.

[0101] FIG. 21 shows a fabricated chipless RFID tag 2104 with a diode-equipped sensing coil 2105, whose overall length was measured to be about 15.5 cm when unfolded next to a straightedge 2103 for experimental validation. In this example, described in a similar context to the prototype 500 of FIG. 5A, the fabricated chipless RFID tag 2104 includes an antenna 2118, a discontinuity 2114 (e.g., CSRR with capacitive stub) arranged between delay sections 2101a, 2101b. The sensing coil 2105 with a Schottky-barrier diode 2125 functions as a PD sensor 2102, and the tag 2104 provides an ID code associated with the asset. When the coil 2105 detects a PD event, the induced voltage in the coil 2105 turns on the diode 2125, changing the impedance seen by the tag 2104. This transmits a signal to a reader (not shown in FIG. 21), such as external reader 124 of FIG. 1B, at the operating frequency at which tag 2104 was interrogated.

[0102] To understand the possible impact of mounting a sensing coil (e.g. 2105) on the insulating elements of the monitored asset, an energized 110 kV high voltage transformer bushing is modeled using CST EM studio, as illustrated in the perspective schematic 2201 of FIG. 22A. The insulation permittivity εr=3. A 10-turn sensing coil 2105 is modeled and placed 15 cm from the top surface of the insulating material. By comparing the simulation results with and without the presence of the coil 2105, as shown in the simulation conclusions 2203, 2205 of FIG. 22B and FIG. 22C respectively, it is found that the electric field distribution in the insulating material is exactly the same as the maximum difference in the insulation directly under the coil 2105, which is less than 5%.

[0103] FIG. 23 shows an equivalent circuit 2301 of the sensing coil 2105 with a diode 2125, Z coil is the equivalent impedance of the coil 2105, and Z diode is the junction resistance R j , junction capacitance C j , and series resistance R s The impedance of the PD sensor 2102 is given by equations (10)-(12).

[0104] Z sensor =Z coil / / Z diode - Equation (10) Where: Z diode =R s +R j / / (-j / ωC j ) - Equation (11) Z coil =R coil +jωL coil - Equation (12)

[0105] Through measurement, L coil = 16.70 μH. Based on the datasheet of Schottky diode 2125 (MMSD 301T1G), C j = 0.9pF and Rj = 52Ω, and R at 200mV forward voltage j = 2kΩ. R s and R coil is usually small and can be ignored. When a PD event turns on diode 2125, at an operating frequency of 2.55 GHz, Z sensor There is a large impedance change of 100 MHz. A PD detection and discrimination measurement system is set up using an oscilloscope (Tektronix DPO7354) 2401, an RF signal generator (Agilent 8648D) 2407, and a directional coupler (AR RF / Microwave Instruments DC7144A) 2405, as shown in the schematic block diagram and photograph in Figure 24A and Figure 24B, respectively. Channels CH1 and CH2 of the oscilloscope 2401 measure the interrogation signal and the reflected signal, respectively. Channel CH3 measures the signal voltage induced by the sensing coil 2105 by measuring across the reference coil 2403. The sampling rate of each channel is set to 10 GS / s with a 3.5 GHz bandwidth. A spark generator 2409 is placed 10 cm away from the coil to emulate a PD event. Since air breakdown occurs at 3000 kV / m, the spark generator 2409 is designed with a 1 mm spark gap energized with a 3 kV pulse. In this setup, no remote communication was required, so the chipless RFID tag 2404 was fabricated without an antenna, discontinuities and a time delay line / section.

[0106] FIG. 25 shows (a) the measured injected signal V based on the equation given in FIG. inj and the received signal V rec By Γ input 1 shows (a) a flowchart illustrating signal processing of the measurement data from which (b) the signal can be calculated; (c) a plot illustrating the relationship between the voltage ratio and time; and (d) a plot illustrating the relationship between the phase difference and time.

[0107] Firstly, the received interrogation signal and the reflected signal are processed using a Windowed Fourier Transform (WFT) with a window size of 3ns, and their respective complex values ​​are extracted at 2.55GHz. Then, the phase difference between the two signals at different time intervals is calculated and stored. The measurement results of four fabricated tags with different phase changes are listed in Table 7.

[0108] [Table 7]

[0109] It should be noted that the phase difference here refers to the phase of the reflected signal relative to the interrogation signal.

[0110] 26 shows an example plot 2601 of data extracted from a reader for four tags equipped with PD sensors in sequential order: CSRR1, CSRR2, SRR2, and SRR1. The first phase change between the interrogation signal and the reflected signal from each tag is the ID code, and the second phase change indicates whether a PD event was detected. Since each tag is mounted to an electrical asset, detection of any PD event may be traced back to a specific asset with a unique ID code.

[0111] As discussed in the above examples, a TD chipless RFID tag with a PD sensor for PD detection and identification has been developed, fabricated, and experimentally verified. The chipless design brings a battery-less and low-cost solution to PD monitoring of critical electrical assets such as high-voltage transformers and motors. The proposed design has demonstrated its ability to detect PD events and identify faulty assets that generate RF emissions associated with PD. Its wireless, battery-less, and compact design allows ease of mounting for multi-asset monitoring and faulty asset identification. The existing diode-mounted sensing coil works well for relatively high strength PDs, but may not be sensitive enough to pick up weak PDs in the early stages of insulation failure because the induced voltage in the coil may not be high enough to turn on the diode. Design improvements such as increasing the number of turns in the coil and choosing a diode with a lower power-on voltage may be considered. Also, a more comprehensive and thorough analysis may be explored to understand the impact of installing a PD sensor on an insulation element, especially when the spacing between the active part and the ground reference is small.

[0112] Although the present invention has been particularly shown and described with reference to specific embodiments, it should be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined in the appended claims. The scope of the present invention is therefore indicated by the appended claims, and all changes that come within the meaning and range of equivalence of the claims are therefore intended to be embraced.

Claims

1. 1. A device releasably connectable to an electrical asset, comprising: a sensor configured to detect partial discharges from the electrical asset and generate a pulsed signal indicative of the presence or absence of the detected partial discharges; a time domain based RFID tag electrically coupled to the sensor, the time domain based RFID tag configured to uniquely provide an ID code representative of the location of the device when coupled to the electrical asset; Equipped with the device is configured to generate a backscatter signal including the ID code and a pulse signal upon interrogation by an external interrogation transmitter, the generated backscatter signal being read by an external reader; device.

2. 10. The device of claim 1, wherein the generated pulse signal including a phase change indicates the presence of the detected partial discharge from the electrical asset, and the generated pulse signal not including a phase change indicates the absence of a detected partial discharge from the electrical asset.

3. 2. The device of claim 1, wherein the sensor comprises at least one sensing coil for detecting the partial discharge and at least one state-change component connected in parallel to the at least one sensing coil and operable to generate the pulse signal.

4. The device of claim 3 , wherein the at least one state-change component comprises a non-linear component.

5. The device of claim 3 , wherein the sensor comprises an additional sensing coil electrically coupled in series with the at least one sensing coil.

6. 6. The device of claim 5, wherein the at least one sensing coil is configured to operate at a first resonant frequency and the further sensing coil is configured to operate at a second resonant frequency, the first resonant frequency being different from the second resonant frequency.

7. 7. The device of claim 1, wherein the at least one sensing coil comprises a plurality of sensing coils configured to operate at different resonant frequencies, each resonant frequency being separated from one another, and to provide an extended bandwidth to the sensor, the extended bandwidth being dependent on the spread of the different resonant frequencies.

8. 7. The device of claim 1, wherein the time domain based RFID tag comprises a delay line including one or more discontinuities, each discontinuity configured to provide one or more unique codes, the unique codes from the one or more discontinuities being used as the ID code.

9. Each discontinuity point is Split ring resonator, or Complementary split-ring resonators, or Combination of split-ring resonators and complementary split-ring resonators The device of claim 8 , comprising one of:

10. The discontinuity is Reconfigurable stub lines, or Reconfigurable stub lines and phase shifters. The device of claim 8 , comprising one of:

11. The device of claim 8 , wherein in the case of two or more discontinuities, each discontinuity is spaced apart from one another.

12. 9. The device of claim 8, wherein the delay line is a composite right / left handed transmission line.

13. 10. The device of claim 8, wherein the time domain based RFID tag further comprises a power divider coupled to the discontinuities and arranged along the delay line in such a manner that the discontinuities are indirectly coupled to the delay line through the power divider, the power divider configured to at least reduce excessive signal reflections from the discontinuities, thereby ensuring that only one signal reflection is performed by the discontinuities.

14. The device of claim 8 , wherein a distal end of the delay line is coupled to the sensor, thereby enabling a time lag to be provided between the ID code and the pulse signal.

15. 15. The device of claim 14, wherein the time domain based RFID tag further comprises an antenna coupled to a proximal end of the delay line, the proximal end being opposite the distal end, the antenna configured to receive an interrogation signal from the external interrogation transmitter.

16. 7. The device of claim 1, further comprising an antenna coupled in series with a time domain based RFID tag, said antenna configured to receive an interrogation signal from the external interrogation transmitter.

17. 7. The device of claim 1, further comprising at least one parameter sensor, each electrically coupled to a time domain based RFID tag, the at least one parameter sensor configured to detect the at least one parameter experienced by the electrical asset to determine an anomalous change in the at least one parameter.

18. The device of claim 1 to 6, wherein the time domain based RFID tag is a time domain based chipless RFID tag.

19. 7. The device of claim 1, wherein the time domain based RFID tag is a time domain chipped based RFID tag, and the device further comprises at least one parameter sensor electrically coupled to the time domain based chipped RFID tag, the at least one parameter sensor configured to detect the at least one parameter experienced by the electrical asset to determine an anomalous change in the at least one parameter.

20. 20. The device of claim 17, wherein the at least one parameter sensor comprises at least one of a temperature sensor, a humidity sensor, a vibration sensor, or a strain sensor.

21. An apparatus comprising: At least one device according to claim 1 to 6, each device being releasably connectable to a respective electrical asset; an external interrogation transmitter configured to interrogate the at least one device to generate a backscatter signal; an external reader configured to read the backscatter signal to obtain an identity of the corresponding electrical asset and information about partial discharges experienced by the corresponding electrical asset; An apparatus comprising:

22. 22. The apparatus of claim 21, wherein the external interrogation transmitter and the external reader are integrated into a single external interrogation transmitter and reader.

23. 1. A method for obtaining an identity of at least one electrical asset and information about partial discharge experienced by the at least one electrical asset, comprising: transmitting an interrogation signal to at least one device by an external interrogation transmitter, each device releasably coupled to a corresponding respective electrical asset; detecting, by each device, the partial discharge from the corresponding electrical asset; generating, by each device, a backscatter signal including an ID code that uniquely represents a location of the device coupled to the corresponding electrical asset and a pulse signal that represents the presence or absence of the detected partial discharge; reading the backscatter signals with an external reader to obtain an identity of the corresponding electrical asset and information about partial discharges experienced by the corresponding electrical asset; A method comprising:

24. 24. The method of claim 23, wherein in the step of generating the backscattered signal, a state-change component of the device remains in a first state when substantially no partial discharge is detected such that the phase of the pulsed signal remains unchanged, and the state-change component is changed to a second state by an induced pulse voltage of the detected partial discharge to cause a phase change of the pulsed signal.

25. 25. The method of claim 23 or 24, wherein the step of detecting the partial discharge comprises capturing the energy of the partial discharge over an extended bandwidth of a sensor of the device, the sensor comprising a plurality of sensing coils operating at different resonant frequencies, the extended bandwidth being dependent on the spread of the different resonant frequencies.

26. 25. The method of claim 23 or 24, wherein the device comprises a time domain based RFID tag with a delay line, and wherein the step of generating the backscattered signal includes providing one or more unique codes by one or more discontinuities in the delay line, and using the unique codes as an ID code.

27. 27. The method of claim 26, wherein the providing one or more unique codes comprises generating the one or more unique codes based on phase shift coded modulation.

28. 28. The method of claim 27, wherein the Phase Shift Coded Modulation is one of 4 Phase Shift Coded Modulation or 16 Phase Shift Coded Modulation.

29. 27. The method of claim 26, further comprising at least reducing excess signal reflections from the discontinuities with a power divider, the power divider being electrically coupled to the discontinuities and arranged along the delay line in such a manner that the discontinuities are indirectly coupled to the delay line through the power divider.

30. 27. The method of claim 26, further comprising receiving the interrogation signal by an antenna of the at least one device.

31. 25. The method of claim 23 or 24, wherein the external interrogation transmitter and the external reader are integrated into a single external interrogation transmitter and reader.

32. 25. The method of claim 23 or 24, further comprising detecting the at least one parameter experienced by the corresponding electrical asset by at least one parameter sensor of each device to determine an abnormal change in the at least one parameter, each of the at least one parameter sensor being electrically coupled to a time domain based RFID tag.

33. 27. The method of claim 26, wherein the time domain based RFID tag is a time domain based chipless RFID tag.

34. 27. The method of claim 26, wherein the time domain based RFID tag is a time domain chipped based RFID tag, the method further comprising detecting the at least one parameter experienced by the corresponding electrical asset with at least one parameter sensor of each device to determine an anomalous change in at least one parameter, the at least one parameter sensor being electrically coupled to the time domain based chipped RFID tag.

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