Non-intrusive partial discharge detection device and method

Abstract

The invention relates to the technical field of partial discharge detection, in particular to a non-intrusive partial discharge detection device and method. The invention aims to provide a novel partial discharge detection technology which has high sensitivity and strong anti-interference capability and can synchronously realize accurate discharge position and intensity and real-time diagnosis, namely a non-intrusive partial discharge detection method, which comprises the following steps: 1) emitting a polarization coded single photon pulse to detected power equipment; the method comprises the steps of (1) receiving a single photon pulse, (2) disturbing the polarization state in the interaction between the single photon pulse and a partial discharge area, (3) collecting returned photons for polarization state decoding, and (4) judging a partial discharge event based on the quantum state distortion degree and carrying out three-dimensional positioning of a discharge source.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of partial discharge detection, in particular to a non-invasive partial discharge detection device and method. BACKGROUND

[0002] In the operation process of high-voltage electrical equipment, when there are defects in the internal or surface of the insulating medium, partial non-through discharge (i.e. partial discharge) is prone to occur under the action of strong electric field. Such discharge usually does not cause through breakdown of the insulating medium, but long-term existence will continuously erode the insulating material, leading to continuous deterioration of the insulating performance, which seriously threatens the safe operation of the equipment and significantly shortens its service life. Therefore, accurate detection of partial discharge and real-time monitoring of discharge quantity trend are key technical requirements for evaluating the insulation state of the equipment, warning potential faults and preventing major accidents.

[0003] For partial discharge detection, the existing technology has developed various methods, but all have significant limitations. The ultra-high frequency (UHF) method detects by capturing the GHz frequency band electromagnetic wave excited by partial discharge, which has high sensitivity, strong anti-interference ability and can realize positioning of the discharge point, but is easily disturbed in a strong electromagnetic field environment, resulting in high false alarm rate. The ultrasonic wave method detects by receiving the pressure wave (ultrasonic wave) generated by discharge, which has high positioning accuracy and excellent anti-electromagnetic interference ability, but the ultrasonic wave signal decays quickly in the medium, resulting in limited sensitivity, short effective detection distance and strict requirements for sensor performance. The pulse current method detects the partial discharge pulse current flowing through the grounding wire, which can quantify the discharge quantity, but its detection accuracy is easily disturbed by noise of the grounding wire, making it difficult to meet the high-precision measurement requirements. The gas decomposition analysis method indirectly evaluates the discharge intensity by detecting the characteristic gas components produced by decomposition of the insulating medium (such as SF6) due to discharge, which can reflect the cumulative effect of discharge, but has serious response lag, which cannot realize real-time monitoring and positioning of discharge. As can be seen, the existing methods have deficiencies in sensitivity, anti-interference ability (especially in complex electromagnetic environment), real-time performance, positioning accuracy and simultaneous realization of multi-dimensional accurate diagnosis of position and intensity. Therefore, it is urgent to develop a new type of partial discharge detection technology with significantly improved sensitivity, excellent anti-interference ability and simultaneous realization of accurate and real-time diagnosis of discharge position and intensity, to meet the urgent needs of accurate evaluation and active warning of high-voltage electrical equipment state. SUMMARY

[0004] The purpose of the present application is to provide a new type of partial discharge detection technology with high sensitivity, strong anti-interference ability and simultaneous realization of accurate and real-time diagnosis of discharge position and intensity, i.e. a non-invasive partial discharge detection device and method.

[0005] The present application is implemented by using the following technical solutions: A non-invasive partial discharge detection device, comprising a quantum polarization light source unit, an optical detection path unit, a polarization analysis unit, an information processing and imaging unit; The quantum polarization light source unit comprises a laser emitter, a polarization modulator, an optical attenuator and an optical lens group arranged in sequence, the laser emitter emits a laser beam, the polarization modulator modulates the laser beam into light pulses of different polarization states (such as horizontal, vertical (H / V), diagonal, anti-diagonal (D / A) or circular polarization (R / L) and the like), and the optical attenuator attenuates the laser intensity of the polarization state light pulse to a level close to a single photon level. The optical detection path unit is used for providing a stable optical path to ensure that the detection photons can reach the to-be-detected region and interact with the partial discharge without interference. The polarization analysis unit comprises a polarization beam splitter, a wave plate group, a single photon avalanche diode (SPAD) array and a time correlation counter, the light pulse interacts with the partial discharge of the to-be-detected region, the photon disturbed by the partial discharge returns to the polarization analysis unit, the photon disturbed by the discharge is decomposed into different polarization components by the polarization beam splitter and the wave plate group according to different polarization states, and the spatially resolved photon counting is performed by the single photon avalanche diode (SPAD) array, and the arrival time and polarization state information of each photon are obtained by combining the time correlation single photon counter. The information processing and imaging unit is used for inputting the measured photon counting data and polarization state information into an FPGA module or an embedded processing unit, calculating the polarization state change rate and quantum state fidelity change of each detection channel (one single photon avalanche diode is one detection channel) in real time, judging whether a partial discharge event occurs, and if the change exceeds a preset threshold, determining that a discharge event occurs.

[0006] Principle description: the application proposes a non-invasive partial discharge detection and three-dimensional positioning scheme based on single photon polarization state preparation and quantum state tomography. The core idea is that a polarization encoded weak light (or single photon level) detection pulse is emitted to the to-be-detected region, the polarization state of the detection light is disturbed after interacting with the transient electromagnetic field, plasma or scatterer generated by the partial discharge; the polarization state of the returned or scattered light is subjected to spatially resolved single photon counting and quantum state reconstruction, the discharge event is identified according to the polarization state distortion, the discharge intensity is quantified, and the three-dimensional position of the discharge source is inverted through the photon arrival time difference and spatial resolution information.

[0007] Further, the optical detection path unit comprises an optical signal transmission channel, a collimator and a lens, and the single photon level light pulse passes through the optical signal transmission channel, the collimator and the lens in sequence and is focused to the to-be-detected region.

[0008] A non-invasive partial discharge detection method, comprising the following steps: 1) Polarization encoded single photon pulses are transmitted to the power equipment under test; 2) The polarization state is disturbed in the interaction with the partial discharge region: 3) The returned photons are collected for polarization state decoding; 4) Partial discharge events are determined based on the degree of quantum state distortion, and three-dimensional positioning of the discharge source is performed.

[0009] The beneficial effects produced by the present application are as follows: The present application adopts single photon level detection sensitivity, which can accurately capture nanosecond level weak discharge pulses, and the sensitivity is improved by one order of magnitude compared with the traditional pulse current method; The system is based on quantum state tomography technology for measurement, which avoids the influence of electromagnetic interference and can work stably in complex electromagnetic environment; Through photon timing and spatial resolution multi-channel data processing, real-time three-dimensional spatial positioning of the partial discharge source is realized; Without accessing the electrical circuit or damaging the equipment insulation, it is suitable for online monitoring of live high voltage equipment. BRIEF DESCRIPTION OF DRAWINGS

[0010] The accompanying drawings, which are incorporated into and form part of the specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the application.

[0011] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the accompanying drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, for those skilled in the art, other drawings can also be obtained based on these drawings without creative labor.

[0012] Figure 1 A structure diagram of the partial discharge detection device described in the present application; Figure 2 A schematic diagram of the partial discharge detection method described in the present application.

[0013] In the figure: 1-laser emitter, 2-polarization modulator, 3-optical attenuator, 4-collimator, 5-lens, 6-polarization beam splitter, 7-wave plate set, 8-single photon avalanche diode array, 9-time correlation counter, 10-FPGA module. DETAILED DESCRIPTION

[0014] In order to more clearly illustrate the above-mentioned purposes, features and advantages of the present application, the scheme of the present application will be further described below. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

[0015] In the description, it needs to be explained that the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance. It needs to be explained that unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting" should be understood in a broad sense, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through intermediate medium, or the communication inside two elements. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0016] In the following description, many specific details are set forth in order to provide a thorough understanding of the present application, but the present application can also be implemented in other ways different from those described herein; obviously, the examples in the description are only part of the examples of the present application, not all examples.

[0017] The specific embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0018] As Figure 1 shown, a non-invasive partial discharge detection device, comprising a quantum polarization light source unit, an optical detection path unit, a polarization analysis unit, an information processing and imaging unit; The quantum polarization light source unit comprises a laser emitter 1, a polarization modulator 2, an optical attenuator 3 and an optical lens 5 arranged in sequence. The laser emitter 1 emits a laser beam. The polarization modulator 2 modulates the laser beam into light pulses of different polarization states (such as horizontal, vertical (H / V), diagonal, anti-diagonal (D / A) or circular polarization (R / L) and other different polarization states). The optical attenuator 3 attenuates the laser intensity of the polarization state light pulse to a single photon level. The optical detection path unit is used to provide a stable optical path to ensure that the detection photons can reach the measured area and interact with the partial discharge without interference. Specifically, it includes an optical signal transmission channel, a collimator 4 and a lens 5. The single photon level light pulse passes through the optical signal transmission channel, the collimator 4 and the lens 5 in sequence and is focused to the measured area; The polarization analysis unit includes a polarization beam splitter 6, a wave plate group 7, a single photon avalanche diode array 8 and a time correlation counter 9. The light pulse interacts with the partial discharge of the measured area, and the photon returned after the disturbance of the partial discharge is sent into the polarization analysis unit. The polarization beam splitter 6 and the wave plate group 7 are used to decompose the photon after the discharge disturbance into different polarization components according to different polarization states, and the single photon avalanche diode array 8 is used to count the spatially resolved photons. Combined with the time correlation single photon counter, the arrival time and polarization state information of each photon are obtained; The information processing and imaging unit is used for inputting the measured photon counting data and polarization state information thereof into the FPGA module 10 or the embedded processing unit, calculating the polarization state change rate and quantum state fidelity change of each detection channel (one single photon avalanche diode is one detection channel) in real time, judging whether a partial discharge event occurs, and if the change exceeds a preset threshold, determining that a discharge event occurs; meanwhile, through the photon timing and spatial resolution multi-channel data processing, the real-time three-dimensional spatial positioning of the partial discharge source is realized.

[0019] Principle description: the application proposes a non-invasive partial discharge detection and three-dimensional positioning scheme based on single photon polarization state preparation and quantum state tomography. The core idea is that: polarized encoding weak light (or single photon level) detection pulses are emitted to the to-be-measured region, after the detection light interacts with the transient electromagnetic field, plasma or scatterer generated by the partial discharge, the polarization state of the detection light is disturbed slightly; the polarization state of the returned or scattered light is subjected to single photon counting and quantum state reconstruction in time and space, the discharge event is identified according to the polarization state distortion, the discharge intensity is quantified, and the three-dimensional position of the discharge source is inversed through the photon arrival time difference and spatial resolution information.

[0020] A non-invasive partial discharge detection method, as shown in Figure 2 , comprising the following steps: 1) emitting polarized encoding single photon pulses to the measured power equipment: the laser and the polarization modulator 2 cooperate to emit single photon pulses with a specific polarization state, and the single photon pulses are focused to the to-be-measured region through the optical detection path unit; 2) polarization state disturbance in the interaction of single photon pulses with the partial discharge area: when the partial discharge occurs, the electromagnetic field and plasma of the discharge area will produce a slight polarization disturbance to the passing single photon pulses, and the electro-optic effect, magneto-optic effect and the like will cause the change of the polarization state when the light pulses pass through the discharge source. This process is the generation source of the partial discharge signal, and the disturbance of the photon polarization state is the target of the system detection; 3) collecting the returned photons for polarization state decoding: the disturbed polarization state single photons return and are processed by the polarization analysis unit, that is, first, the polarization beamsplitter 6 separates different polarization components; then, the separated polarization state photons are subjected to spatial resolution photon counting by the single photon avalanche diode array 8, and meanwhile, the arrival time of each photon is recorded by the time correlation single photon counter. The high-precision photon counting and polarization information decoding help to restore the polarization state change of the partial discharge event, and ensure that the discharge intensity can be accurately quantified; 4) Determine partial discharge events based on quantum state distortion degree, and perform three-dimensional positioning of discharge source and discharge intensity quantification: When no partial discharge occurs (system calibration stage), input the photon polarization state information and photon arrival time data obtained in step 3) into the field programmable gate array (FPGA module 10), the FPGA module 10 calculates the polarization state change rate of the detection light path, establishes the spatial coordinate mapping relationship of the light path, and determines the quantum state distortion degree threshold based on the background noise; when partial discharge occurs (detection and positioning stage), input the real-time data obtained in step 3) into FPGA 10; FPGA 10 identifies the polarization state change rate change that exceeds the calibration threshold to determine the occurrence of discharge event, and calculates the three-dimensional spatial position of the discharge source based on the spatial coordinate mapping relationship and the photon arrival time difference, while quantifying the discharge intensity.

[0021] The discharge intensity is defined as the degree of quantum state distortion caused by the discharge source, which is directly calculated from the quantum state tomography data. It is directly proportional to the disturbance amplitude of the partial discharge event on the polarization state of the detected photons. Specifically, the numerical value of the discharge intensity reflects the degree of small disturbance of the photon polarization state by the partial discharge process.

[0022] The introduction of the FPGA module 10 enables the system to perform data processing and real-time decision-making within nanosecond time range. By calculating the polarization state change rate and the distortion degree of the quantum state in real time, the system can timely determine the occurrence of partial discharge events, and realize real-time three-dimensional positioning through the inversion algorithm of spatial position and intensity. This step is the core data processing part, which realizes accurate three-dimensional positioning and intensity quantification of the partial discharge source through quantum state reconstruction and spatiotemporal positioning method.

[0023] In specific implementation, the path difference between the two detectors is calculated by calculating the photon arrival time difference between different detection channels, using the speed of light and the refractive index of the medium.

[0024] Among them, the speed of light and the refractive index of the medium are known, and the photon arrival time difference is measured by the system. The calculation of the path difference is based on these known parameters. Through this relationship, the system can accurately estimate the difference between the photon propagation paths of the two different detectors.

[0025] To improve the accuracy of the estimation, the least squares method is used for optimization calculation.

[0026] By minimizing the error between the predicted path difference and the actual path difference, the system can optimize the calculation result and accurately estimate the spatial position of the partial discharge source.

[0027] In a specific implementation, the device fits the photon counting data in each measurement basis by maximum likelihood estimation (MLE) or other quantum state reconstruction algorithm, and obtains the quantum state density matrix corresponding to the spatial position. Then, the discharge intensity is defined by quantifying the distortion degree of the matrix. The discharge intensity is proportional to the change in fidelity between the measurement state and the reference state, reflecting the disturbance intensity of the local discharge on the polarization state of the photon. When the discharge intensity exceeds the preset threshold, the system will determine that a discharge event has occurred.

[0028] The quantum state density matrix is calculated by a quantum state reconstruction algorithm based on the photon counting data in four different measurement basis vectors, thereby completely characterizing the polarization state properties of the detected photons at a specific spatial position. The matrix provides the distribution of the photons in each measurement basis vector, providing necessary data for subsequent quantum state analysis and calculation.

[0029] The above is only a specific implementation of the present application, enabling those skilled in the art to understand or implement the present application. Although detailed descriptions are made with reference to the foregoing embodiments, those of ordinary skill in the art should understand that the technical solutions described in the foregoing embodiments can be modified, or some or all of the technical features can be replaced equivalently; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments, and they should all be covered in the protection scope of the claims.

Claims

1. A non-intrusive partial discharge detection device, characterized in that, The quantum polarization light source unit, the optical detection path unit, the polarization analysis unit, the information processing and imaging unit are included. The quantum polarization light source unit includes a laser emitter, a polarization modulator, an optical attenuator and an optical lens group arranged in sequence. The laser emitter emits a laser beam. The polarization modulator modulates the laser beam into light pulses of different polarization states. The optical attenuator attenuates the laser intensity of the polarization state light pulses to a level close to a single photon level. The optical detection path unit is used to provide a stable optical path to ensure that the detection photons can reach the area to be detected and interact with the partial discharge without interference. The polarization analysis unit includes a polarization beam splitter, a wave plate group, a single photon avalanche diode array and a time correlation counter. The light pulses interact with the partial discharge of the area to be detected. The photons disturbed by the partial discharge return to the polarization analysis unit. The polarization beam splitter and the wave plate group decompose the photons disturbed by the discharge into different polarization components according to different polarization states. The single photon avalanche diode array performs spatially resolved photon counting. The time correlation single photon counter obtains the arrival time and polarization state information of each photon. The information processing and imaging unit is used to input the measured photon counting data and polarization state information into an FPGA module or an embedded processing unit to calculate the polarization state change rate and quantum state fidelity change of each detection channel in real time. Based on these changes, it is determined whether a partial discharge event occurs. If the change exceeds the preset threshold, it is determined that a discharge event occurs.

2. The non-invasive partial discharge detection device according to claim 1, characterized in that The information processing and imaging unit also realizes real-time three-dimensional spatial positioning of the partial discharge source through photon timing and spatially resolved multi-channel data processing.

3. The non-invasive partial discharge detection device according to claim 1, characterized in that The optical detection path unit includes an optical signal transmission channel, a collimator and a lens. Single photon level light pulses pass through the optical signal transmission channel, the collimator and the lens in sequence and focus on the area to be detected.

4. A non-invasive partial discharge detection method, characterized in that, The method includes the following steps: 1) Emitting polarization encoded single photon pulses to the power equipment to be measured; 2) The polarization state is disturbed in the interaction with the partial discharge area; 3) Collecting the returned photons for polarization state decoding; 4) Determining the partial discharge event based on the quantum state distortion degree and performing three-dimensional positioning of the discharge source.

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