Partial discharge measurement and analysis device of generator

Abstract

The invention relates to a partial discharge measurement and analysis device of a generator, which is mounted on a three-phase power line of the generator and comprises a high-frequency current transformer, a fluorescent optical fiber, an ultrahigh-frequency sensor, a band-pass filter, a photomultiplier, a biasing circuit, an amplifier, a lock-in amplifier and an analyzer, a plurality of high-frequency current transformers and ultrahigh-frequency sensors are arranged in three groups and respectively correspond to three phases on the three-phase power line; after the high-frequency current transformer and the ultrahigh-frequency sensor in each group are connected in series through the fluorescent optical fiber, one end is mounted on one phase of the three-phase power line, and the other end is connected to the band-pass filter; and the band-pass filter, the photomultiplier, the biasing circuit, the amplifier, the lock-in amplifier and the analyzer are connected in sequence, and are used for carrying out partial discharge detection on the generator according to detection signals of the high-frequency current transformer and the ultrahigh-frequency sensor. Compared with the prior art, the device has the advantages of wide measurement range, high sensitivity, convenience in measurement, long service life and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of generator partial discharge detection, in particular to a partial discharge measurement and analysis device for a generator. BACKGROUND

[0002] Detecting the partial discharge of a generator is an important means of monitoring the insulation state of a power system, but due to the complex environment and signal characteristics on site, its detection faces many technical difficulties.

[0003] Firstly, there is strong electromagnetic interference, and there is a large amount of electromagnetic noise (such as excitation system pulses, arc discharge, etc.) in the operation site of the generator, and the partial discharge signal (usually microvolt level) is easy to be submerged. Traditional hardware filtering methods are difficult to completely eliminate interference, especially narrow-band noise overlapping with the partial discharge signal frequency band. Secondly, signal recognition and pattern classification are difficult. It lacks a unified discharge pulse feature library, and the waveforms, frequencies and amplitudes of different defects (such as stator winding discharge, slot discharge and end discharge) are quite different. The interference pulse and the real partial discharge signal may be similar in time-frequency domain features, and the traditional threshold method is easy to misjudge. At the same time, the weak signal collection and waveform are easy to be distorted. The partial discharge signal is small (picocoulomb level), and the high-frequency components are easy to attenuate in the transmission process. The wideband filter and amplifier may introduce waveform distortion, leading to misjudgment. Finally, the real-time performance and reliability of the monitoring need to be further explored. Offline detection cannot reflect the real insulation state under the running condition, while online monitoring needs to consider the data volume, transmission speed and analysis accuracy. The installation of the sensor may also affect the reliability of the generator protection system (such as zero sequence voltage protection).

[0004] At present, ultra-high frequency monitoring technology is usually used at home and abroad to monitor partial discharge, but this measurement method has some shortcomings in terms of environmental interference resistance and recognition accuracy. SUMMARY

[0005] The purpose of the present application is to overcome the shortcomings of the prior art and provide a partial discharge measurement and analysis device for a generator, which improves the environmental interference resistance and recognition accuracy.

[0006] The purpose of the present application can be achieved by the following technical solutions:

[0007] A partial discharge measurement and analysis device for a generator is installed on the three-phase power supply line of the generator, comprising a high-frequency current transformer, a fluorescent optical fiber, an ultra-high frequency sensor, a band-pass filter, a photomultiplier tube, a bias circuit, an amplifier, a lock-in amplifier and an analyzer.

[0008] The number of the high-frequency current transformers and the ultra-high frequency sensors is multiple, and the high-frequency current transformers and the ultra-high frequency sensors are divided into three groups and correspond to three-phase power lines; the high-frequency current transformers and the ultra-high frequency sensors in each group are connected in series through fluorescent optical fibers, and one end of the series connection is installed on one of the three-phase power lines, and the other end is connected to a band-pass filter.

[0009] The band-pass filter, the photomultiplier tube, the bias circuit, the amplifier, the lock-in amplifier and the analyzer are connected once, and are used for detecting partial discharge of the generator according to the detection signals of the high-frequency current transformers and the ultra-high frequency sensors.

[0010] Further, the fluorescent optical fiber is an insulating material, which is a quartz material.

[0011] Further, the fluorescent optical fiber is coated with fluorescent material at the end or local area of the optical fiber, when the excitation light is transmitted to the area where the fluorescent material is located through the optical fiber, the fluorescent material is excited and emits characteristic fluorescence, which is transmitted back to the detection end through the optical fiber.

[0012] Further, the high-frequency current transformer is used for detecting high-frequency pulse current of the generator in the frequency range of 3-30 MHz, and conducting conductor discharge detection.

[0013] Further, the ultra-high frequency sensor is used for detecting electromagnetic wave signals of the generator in the frequency range of 300 MHz-3 GHz, and conducting insulation defect detection.

[0014] Further, the band-pass filter is used for filtering out power frequency interference and high-frequency noise according to the frequency range of the detection signals of the high-frequency current transformer and the ultra-high frequency sensor.

[0015] Further, the photomultiplier tube is used for converting the received optical signal into an electrical signal.

[0016] Further, the bias circuit is used for providing stable DC bias for the subsequent amplifier, and ensuring that the detection signal is in the optimal working interval.

[0017] Further, the amplifier is used for preliminarily amplifying the detection signal; and the lock-in amplifier is used for suppressing noise and extracting micro-volt level discharge signals through phase-sensitive detection technology.

[0018] Further, the analyzer is used for analyzing the signals output by the lock-in amplifier based on an AI algorithm, distinguishing the types of partial discharge, and dynamically displaying the time domain and frequency domain characteristics of the discharge pulse.

[0019] Compared with the prior art, the present application has the following advantages:

[0020] (1) Compared with the traditional ultrahigh frequency measurement technology, the device greatly improves the monitoring ability of the partial discharge signal below 300MHz band, and is not easily affected by environmental interference. The fluorescent optical fiber uses insulating materials (such as quartz), which is completely not affected by the strong electromagnetic field inside the generator, avoiding the signal distortion caused by electromagnetic interference of the traditional electronic sensor. The fluorescent material is sensitive to the ultraviolet light / visible light generated by the partial discharge, which can detect early weak discharge and prevent insulation deterioration.

[0021] This device also ensures the cooperative detection of multiple physical quantities, improves the sensitivity and measurement range. HFCT is to detect the high-frequency pulse current (3-30MHz) of the generator ground line or neutral point, quantify the intensity of partial discharge, especially sensitive to the discharge near the conductor. UHF is to capture the ultrahigh frequency electromagnetic wave (300MHz-3GHz) excited by partial discharge, which is suitable for detecting internal insulation defects, and can effectively avoid low-frequency electromagnetic interference. The combination of the two can have good complementarity. HFCT is sensitive to conductor discharge, while UHF is more effective for insulation defects (such as air gap, surface discharge), and the combination of the two can cover a wider range of fault types. The combination of high-frequency current transformer (HFCT) and ultrahigh frequency (UHF) sensor for generator partial discharge (PD) monitoring can significantly improve the sensitivity, accuracy and anti-interference ability of detection, thereby providing more reliable technical support for the safe operation and condition-based maintenance of the generator.

[0022] (2) Long service life, corrosion and high temperature resistance. Optical fiber has no metal components, no electric spark, suitable for environments with flammable gases (such as hydrogen-cooled generators) or high temperature and high pressure environments. It is resistant to moisture, oil and chemical corrosion, and has better long-term stability than electronic sensors.

[0023] (3) Convenient measurement. Using a handheld PDA power measurement instrument can perform partial discharge monitoring. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 A structure diagram of a partial discharge measurement and analysis device for a generator is provided in the embodiments of the present application. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical scheme and advantages of the embodiments of the present application more clear, the technical scheme in the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0026] Therefore, the following detailed description of the embodiments of the application provided in the drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of the application. All other embodiments obtained based on the embodiments of the application by one of ordinary skill in the art without creative work are within the scope of the protection of the application.

[0027] It should be noted that similar reference numbers and letters represent similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0028] In the description of the application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the application is usually placed, and are merely for the convenience of describing the application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the application.

[0029] It should be noted that the terms "first" and "second" are used only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features referred to. Therefore, the features defined with "first" and "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise specifically limited.

[0030] In addition, the terms "horizontal", "vertical", and the like do not mean that the components must be absolutely horizontal or vertical, but can be slightly inclined. For example, "horizontal" only means that it is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but can be slightly inclined.

[0031] Embodiment 1

[0032] As shown in Figure 1 The present embodiment provides a partial discharge measurement and analysis device of a generator, which is installed on a three-phase power line of a generator, and includes a high-frequency current transformer 1, a fluorescent optical fiber 2, a ultra-high frequency sensor 3, a band-pass filter 4, a photomultiplier tube 5, a bias circuit 6, an amplifier 7, a lock-in amplifier 8, and an analyzer 9.

[0033] The number of high-frequency current transformers 1 and ultra-high frequency sensors 3 is multiple, and they are divided into three groups and correspond to three phases on the three-phase power line. The high-frequency current transformers 1 and ultra-high frequency sensors 3 in each group are connected in series through the fluorescent optical fiber 2, and one end is installed on one phase of the three-phase power line, and the other end is connected to the band-pass filter 4.

[0034] The band-pass filter 4, the photomultiplier tube 5, the bias circuit 6, the amplifier 7, the lock-in amplifier 8 and the analyzer 9 are connected once to detect the partial discharge of the generator according to the detection signals of the high-frequency current transformer 1 and the ultra-high frequency sensor 3.

[0035] Accordingly, the partial discharge measurement and analysis device in the scheme is connected through three-phase power supply, and the high-frequency current transformer 1 and the ultra-high frequency sensor 3 are installed for each phase and connected through the fluorescent optical fiber 2. Then the current of different wavelengths is filtered through the band-pass filter 4, and then the current is amplified through the photomultiplier tube 4, the bias circuit 5, the amplifier 6 and the lock-in amplifier 7. Finally, the analyzer 9 with a touch screen is connected to detect the partial discharge signal of the generator.

[0036] Specifically, the fluorescent optical fiber 2 is an insulating material, which can be quartz material. The monitoring capability of the fluorescent optical fiber for the partial discharge signal below 300 MHz is greatly improved, and it is not easy to be affected by environmental interference. The fluorescent optical fiber adopts an insulating material (such as quartz), which is completely not affected by the strong electromagnetic field inside the generator, thereby avoiding the signal distortion of the traditional electronic sensor caused by electromagnetic interference. The fluorescent material is sensitive to the ultraviolet light / visible light generated by the partial discharge, and can detect early weak discharge to prevent insulation deterioration.

[0037] The fluorescent optical fiber adopts a single-point arrangement form, and the fluorescent material is coated / doped at the end or local area of the optical fiber; the excitation light is transmitted to the fluorescent area through the optical fiber, and the emission light returns to the detection end.

[0038] When the excitation light is transmitted to the area coated / doped with the fluorescent material through the optical fiber, the fluorescent material is excited and emits characteristic fluorescence. These fluorescence signals are transmitted back to the detection end through the optical fiber, and after photoelectric conversion and signal processing, quantitative analysis of the target substance can be realized.

[0039] The fixing form of the fluorescent optical fiber is: mechanical fixing method (clamping fixing): a metal / plastic clamp is used to fix the optical fiber on a substrate or a support. This mode is detachable and flexible to adjust, and can avoid excessive compression to cause optical fiber micro-bending loss.

[0040] The high-frequency current transformer 1 HFCT is used to detect the high-frequency pulse current (3-30 MHz) of the generator ground wire or neutral point, quantify the intensity of the partial discharge, and is particularly sensitive to the discharge near the conductor.

[0041] The ultra-high frequency sensor 3 UHF is used to capture the ultra-high frequency electromagnetic wave (300 MHz-3 GHz) excited by the partial discharge, which is suitable for detecting internal defects of insulation and can effectively avoid low-frequency electromagnetic interference.

[0042] The combination of the two can have good complementarity. HFCT is sensitive to conductor discharge, while UHF is more effective for insulation defects (such as air gap, surface discharge), and the combination of the two can cover a wider range of fault types. The combination of high-frequency current transformer (HFCT) and ultra-high frequency (UHF) sensor for generator partial discharge (PD) monitoring can significantly improve the sensitivity, accuracy and anti-interference ability of detection, thereby providing more reliable technical support for the safe operation and condition-based maintenance of the generator.

[0043] The band-pass filter 4 is used to filter out power frequency interference and high-frequency noise according to the frequency band range of the high-frequency current transformer 1 and the ultra-high frequency sensor 3 detection signal. Among them, the power frequency interference refers to 50Hz (or 60Hz) and its harmonics (such as 100Hz, 150Hz, etc.), which are concentrated in the low frequency band. High-frequency noise may come from switching power supply, radio signal, digital circuit, etc.

[0044] The photomultiplier tube 5 is used to convert the received optical signal into an electrical signal.

[0045] The bias circuit 6 is used to provide stable DC bias for the subsequent amplifier 7, ensuring that the detection signal is in the optimal working interval.

[0046] The amplifier 7 is used to preliminarily amplify the detection signal; the phase-locked amplifier 8 is used to suppress noise and extract microvolt-level discharge signals through phase-sensitive detection technology.

[0047] The analyzer 9 is used to analyze the signal output by the phase-locked amplifier 8 based on AI algorithm, distinguish the type of partial discharge, and dynamically display the time domain and frequency domain characteristics of the discharge pulse.

[0048] Working principle:

[0049] The device is used for real-time monitoring of partial discharge signals during generator operation. Through multi-sensor fusion and high-precision signal processing technology, accurate extraction, amplification and analysis of discharge signals are realized. Its working principle can be divided into three stages: signal acquisition, signal conditioning and data analysis.

[0050] The signal acquisition module adopts a three-phase (A / B / C) synchronous detection architecture, each phase is equipped with: high-frequency current transformer 1 (HFCT) and ultra-high frequency sensor 3 (UHF), which are used to capture discharge signals of different frequency bands. Among them, HFCT (frequency band: 3MHz-30MHz) is used to detect pulse current signals caused by partial discharge, and UHF (frequency band: 300MHz-3GHz) is used to receive electromagnetic wave signals excited during discharge process. The signals collected by the sensor are transmitted through the anti-interference fluorescent optical fiber 2, effectively avoiding electromagnetic noise interference and ensuring high-fidelity transmission of signals.

[0051] Signal conditioning module is the original signal needs to be processed by multiple levels to improve the signal-to-noise ratio and extract effective features. Band-pass filter 4 filters out power frequency interference and high frequency noise according to the typical frequency band of discharge signal (such as different working range of HFCT and UHF). At the same time, photomultiplier 5 converts weak light signal into electrical signal. Bias circuit 6 provides stable DC bias for subsequent amplification circuit, ensuring that the signal is in the best working interval. Low noise amplifier 7: preliminary amplification of weak discharge signal, improve detection sensitivity. Finally, the phase-locked amplifier 8 is through the phase-sensitive detection technology, further suppress the noise and extract micro-volt level discharge signal, enhance the anti-interference ability of the system.

[0052] Finally, the data analysis and display module transmits the processed signal to the touch-sensitive intelligent analyzer 9, which integrates the following functions. Real-time waveform display is to dynamically display the time domain and frequency domain characteristics of the discharge pulse. Pattern recognition is to automatically distinguish internal discharge, surface discharge and corona discharge based on AI algorithm. At the same time, trend analysis is formed, historical data is recorded and insulation deterioration trend is predicted, providing early warning function.

[0053] The above describes the preferred embodiments of the present application in detail. It should be understood that those skilled in the art can make many modifications and changes without creative labor according to the concept of the present application. Therefore, any technical solution obtained by logical analysis, reasoning or limited experiment on the basis of the prior art according to the concept of the present application shall be within the protection scope determined by the claims.

Claims

1. A partial discharge measurement and analysis device for a generator, installed on the three-phase power lines of the generator, characterized in that, It includes a high-frequency current transformer (1), a fluorescent optical fiber (2), an ultra-high frequency sensor (3), a bandpass filter (4), a photomultiplier tube (5), a bias circuit (6), an amplifier (7), a lock-in amplifier (8), and an analyzer (9); The number of high-frequency current transformers (1) and ultra-high frequency sensors (3) are multiple and are set in three groups, corresponding to the three phases of the three-phase power line respectively. The high-frequency current transformers (1) and ultra-high frequency sensors (3) in each group are connected in series through fluorescent optical fibers (2), and one end is installed on one phase of the three-phase power line, and the other end is connected to a bandpass filter (4). The bandpass filter (4), photomultiplier tube (5), bias circuit (6), amplifier (7), lock-in amplifier (8) and analyzer (9) are connected in one step to detect partial discharge of the generator based on the detection signals of the high-frequency current transformer (1) and the ultra-high frequency sensor (3).

2. The partial discharge measurement and analysis device for a generator according to claim 1, characterized in that, The fluorescent optical fiber (2) is an insulating material, which is quartz.

3. The partial discharge measurement and analysis device for a generator according to claim 1, characterized in that, The fluorescent optical fiber (2) is coated with fluorescent material at the end or in a local area of ​​the optical fiber. When the excitation light is transmitted through the optical fiber to the area where the fluorescent material is located, the fluorescent material is excited and emits characteristic fluorescence, which is transmitted back to the detection end through the optical fiber.

4. The partial discharge measurement and analysis device for a generator according to claim 1, characterized in that, The high-frequency current transformer (1) is used to detect the high-frequency pulse current of the generator in the 3-30MHz frequency band and to perform conductor discharge detection.

5. The partial discharge measurement and analysis device for a generator according to claim 1, characterized in that, The ultra-high frequency sensor (3) is used to detect electromagnetic wave signals of the generator in the frequency range of 300MHz to 3GHz to detect insulation defects.

6. The partial discharge measurement and analysis device for a generator according to claim 1, characterized in that, The bandpass filter (4) is used to filter out power frequency interference and high frequency noise based on the frequency range of the signals detected by the high frequency current transformer (1) and the ultra-high frequency sensor (3).

7. The partial discharge measurement and analysis device for a generator according to claim 1, characterized in that, The photomultiplier tube (5) is used to convert the received optical signal into an electrical signal.

8. The partial discharge measurement and analysis device for a generator according to claim 1, characterized in that, The bias circuit (6) is used to provide a stable DC bias for the subsequent amplifier (7) to ensure that the detection signal is in the optimal operating range.

9. The partial discharge measurement and analysis device for a generator according to claim 1, characterized in that, The amplifier (7) is used to initially amplify the detection signal; the lock-in amplifier (8) is used to suppress noise and extract microvolt-level discharge signals through phase-sensitive detection technology.

10. The partial discharge measurement and analysis device for a generator according to claim 1, characterized in that, The analyzer (9) is used to analyze the signal output by the lock-in amplifier (8) based on the AI ​​algorithm, distinguish the type of partial discharge, and dynamically display the time domain and frequency domain characteristics of the discharge pulse.

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