CN115219854A - Partial discharge monitoring system and method based on multiple sensors - Google Patents

Abstract

The invention relates to a partial discharge monitoring system and a partial discharge monitoring method based on multiple sensors, wherein the system comprises a sensor module, a front-end module, a monitoring host, a network module, a mobile end and a monitoring end, wherein the sensor module is connected with the front-end module, the front-end module is connected with the monitoring host, the monitoring host is connected with the network module, and the mobile end and the monitoring end are respectively connected with the network module; the sensor module is composed of at least two sensors of different types, and partial discharge signals received by the sensors of different types are mutually verified. Compared with the prior art, the invention has the advantages of obviously improving the accuracy of the partial discharge monitoring system, avoiding misjudgment, misalarming and the like.

Description

Partial discharge monitoring system and method based on multiple sensors

Technical Field

The invention relates to a partial discharge monitoring technology, in particular to a partial discharge monitoring system and method based on multiple sensors.

Background

The live-line detection technology of the national power grid power equipment is mentioned in the red book, 85% of electrical accidents are caused by the fact that the partial discharge phenomenon is not detected in the early stage, if the partial discharge phenomenon can be monitored in the early stage, over 80% of electrical safety accidents can be predicted in advance, and loss of people and assets caused by the electrical accidents is avoided. According to the statistical data of the fault factors of the electrical equipment, the insulation aging of the electrical equipment can be found to be one of important reasons for causing the fault of the electrical equipment.

The existing partial discharge monitoring system mainly has the following problems: (1) Generally, only one type of sensor is used, and the sensor is easily interfered by environmental noise, so that the situations of missing alarm and false alarm occur (for example, chinese patent publication numbers CN110703062A and CN112379232A and the like). (2) The partial discharge signal at the initial stage of insulation degradation cannot be detected, and the repair and maintenance cannot be carried out in time, so that the insulation failure is accelerated, and the system operation cost is increased. And (3) the device does not have the functions of monitoring and managing the whole life cycle.

Disclosure of Invention

The present invention is directed to overcoming the above-mentioned drawbacks of the prior art and providing a partial discharge monitoring system and method based on multiple sensors.

The purpose of the invention can be realized by the following technical scheme:

according to one aspect of the invention, a partial discharge monitoring system based on multiple sensors is provided, which comprises a sensor module, a front-end module, a monitoring host, a network module, a mobile terminal and a monitoring terminal, wherein the sensor module is connected with the front-end module, the front-end module is connected with the monitoring host, the monitoring host is connected with the network module, and the mobile terminal and the monitoring terminal are respectively connected with the network module; the sensor module is composed of at least two sensors of different types, and partial discharge signals received by the sensors of different types are mutually verified.

As a preferable technical scheme, the different types of sensors comprise a high-frequency current transformer HFCT, an ultrahigh-frequency current transformer UHFCT, an instantaneous ground voltage sensor and an ultrasonic sensor.

As a preferable technical solution, the high frequency current transformer HFCT is a Rogowski coil current sensor, and a magnetic core with high magnetic permeability is used as a framework of the Rogowski coil.

As a preferred technical solution, the sensor module includes a high frequency current transformer HFCT and an ultrahigh frequency current transformer UHFCT.

As a preferred technical scheme, the front-end module comprises a local discharge signal acquisition circuit and a local discharge signal processing circuit which are connected with each other; the partial discharge signal acquisition circuit is connected with the sensor module, and the partial discharge signal processing circuit is connected with the monitoring host;

the partial discharge signal acquisition circuit is used for acquiring partial discharge signals, and the partial discharge signal processing circuit is used for processing the partial discharge signals.

As a preferred technical solution, the network module includes a router and a cloud server which are connected to each other, the router is connected to the monitoring host and the monitoring terminal, and the cloud server is connected to the mobile terminal.

As a preferred technical scheme, the mobile terminal is a mobile phone, a tablet computer or a notebook computer.

As a preferable technical scheme, the front-end module and the monitoring host are arranged in a protective box, and the sensor module is connected with the front-end module through an RG58 cable.

According to another aspect of the present invention, there is provided a method for the multiple sensor based partial discharge monitoring system, comprising the steps of:

step one, partial discharge signals extracted by multiple sensors at the same time are reserved, and partial discharge signals extracted by a single sensor are discarded;

step two, converting the partial discharge signals retained in the step one in a time domain and a frequency domain, calculating the equivalent time T and the equivalent frequency F of each pulse, projecting the equivalent time T and the equivalent frequency F to a 2-dimensional T-F plane, drawing a TF mapping chart, performing cluster analysis on the TF mapping chart, and separating the partial discharge signals according to the difference between noise clustering and the partial discharge signal clustering;

step three, drawing the amplitude value, the extraction time and the power frequency voltage waveform of the partial discharge signal retained in the step two in the same graph, namely a PRPD spectrogram, and discarding the partial discharge signals appearing in a second quadrant and a fourth quadrant according to the spectrogram;

and step four, amplifying the partial discharge signals screened out in the step three by using an oscilloscope to completely present the waveforms of the partial discharge signals, comparing the partial discharge signals with the partial discharge standard waveforms defined by IEC 60270 through a convolutional neural network or a support vector machine algorithm, performing fast Fourier transform on the partial discharge signals screened out in the step three to obtain frequency spectrums of the partial discharge signals, and comprehensively judging the discharge types according to the time domain waveforms and the frequency spectrums.

As a preferred technical solution, the specific judgment method of the first step is as follows: in the interval of [ t, t + delta t ], if more than half of the sensors detect partial discharge signals, the partial discharge is considered to be really generated, otherwise, the detected partial discharge signals are considered to be the ambient environment interference;

where t is the time recorded by the sensor that first detected the partial discharge signal, and Δ t is the maximum time difference between the multiple sensors detecting the same partial discharge signal.

Compared with the prior art, the invention can continuously monitor the partial discharge signal of the power equipment on line for 24 hours, and has the advantages of high sensitivity, accurate judgment, capability of identifying the partial discharge signal at the initial stage of insulation degradation, simple and rapid data reporting, convenient installation and use and the like. After partial discharge occurs to the equipment, the insulation state of the power equipment can be predicted in time, and related power equipment maintenance or replacement plans are formulated, so that the monitoring and management of the whole life cycle of the power equipment are realized, and the safety and stable operation of a power system are effectively guaranteed.

Drawings

FIG. 1 is a schematic structural view of the present invention;

FIG. 2 is a schematic diagram of the structure of a Rogowski coil in accordance with the present invention;

FIG. 3 is a typical TF map;

FIG. 4 is a partial discharge PRPD spectrum;

the system comprises a sensor module 1, a front-end module 2, a monitoring host 3, a network module 4, a mobile terminal 5, a monitoring terminal 6, a high-frequency current transformer HFCT11, an ultrahigh-frequency current transformer UHFCT12, an instantaneous ground voltage sensor 13, a partial discharge signal acquisition circuit 21, a partial discharge signal processing circuit 22, a router 41 and a cloud server 42.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, not all, embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, shall fall within the scope of protection of the present invention.

The invention provides a high-precision partial discharge online monitoring system and method based on multiple sensors, wherein on hardware, multiple types of sensors are used simultaneously, and on software, technologies such as partial discharge phase distribution (PRPD) spectrogram analysis, real-time waveform characteristic extraction, signal grouping noise filtering, spectrum analysis and the like are comprehensively applied, so that the precision of the partial discharge monitoring system is obviously improved, and misjudgment and misalarming are avoided. The provided online monitoring system can update monitoring data in real time, and sends an alarm signal to a central control room and related responsible persons at the first time, so that the timeliness of information transmission is improved.

The invention is suitable for the on-line monitoring of partial discharge of various power equipment such as Gas Insulated Switchgear (GIS), transformers, generators, power distribution cabinets, cables and the like.

As shown in fig. 1, a partial discharge monitoring system based on multiple sensors includes a sensor module 1, a front-end module 2, a monitoring host 3, a network module 4, a mobile terminal 5 and a monitoring terminal 6, where the sensor module 1 is connected to the front-end module 2, the front-end module 2 is connected to the monitoring host 3, the monitoring host 3 is connected to the network module 4, and the mobile terminal 5 and the monitoring terminal 6 are respectively connected to the network module 4; the sensor module 1 is composed of at least two sensors of different types, and partial discharge signals received by the sensors of different types are verified mutually, so that the partial discharge judgment precision is remarkably improved.

The different types of sensors described include a high frequency current transformer HFCT11, an ultrahigh frequency current transformer UHFCT12, an instantaneous ground voltage sensor 13 and an ultrasonic sensor.

In the technical scheme, the lowest sampling level, the least sampling times and the least sampling time are set by the monitoring host 3; the front-end module 2 stores a sampling level (mV), obtains a discharge waveform through the sensor module 1, judges whether the discharge waveform is greater than the sampling level, and the monitoring host 3 records and judges whether partial discharge exists through a partial discharge algorithm. When the partial discharge times are accumulated to affect the insulation system of the electrical equipment, the monitoring host actively sends an alarm signal to the upper stage in time through the network module 4. Meanwhile, an alarm relay in the partial discharge monitoring system acts to output a passive contact signal, the alarm signal is displayed on a liquid crystal display screen, and meanwhile, the background monitoring computer sends alarm information to an email and a specified mobile phone of a user through a network. Through the technical scheme, the judgment result of the monitoring host 3 can be transmitted to the monitoring terminal of the central control room through the network module 4 or transmitted to the mobile terminal through the cloud server, so that maintenance personnel can conveniently receive related information of partial discharge.

In this embodiment, the sensor module 1 includes an HFCT sensor and a UHF sensor, the HFCT sensor is a high-frequency current sensor, and the UHF sensor is an ultra-high frequency electromagnetic wave sensor. Through double physical quantity detection, the alarm accurate report rate of the partial discharge signal is improved, and the conditions of false alarm and alarm leakage in the process of partial discharge online monitoring can be effectively avoided.

An HFCT sensor, i.e. a Rogowski coil current sensor, is shown in fig. 2. Preferably, the present invention intends to use a magnetic core with high permeability as the framework of the Rogowski coil to improve the sensitivity of HFCT. When the detector is used, a conductor to be detected penetrates through the annular coil, and the integral of the current with respect to time is output. When partial discharge occurs, high-frequency pulse current is generated on a grounding wire by charge transfer caused by the discharge, the current generates a magnetic field in the surrounding space, and the HFCT acquires energy from the magnetic field generated by the partial discharge and converts the energy into current in a secondary coil through electromagnetic coupling, so that a partial discharge signal is accurately and effectively extracted.

The UHFCT has good corona resistance, high working frequency and large attenuation to environmental noise, so the UHFCT is very suitable for on-line monitoring of partial discharge. The partial discharge in the insulating medium can be neutralized by positive and negative charges every time, 1 steep current pulse is accompanied, ultrahigh frequency electromagnetic waves are radiated to the periphery, and the partial discharge can be monitored by detecting the ultrahigh frequency electromagnetic waves.

The network module comprises a router and a cloud server, and the router is electrically connected with the cloud server. The mobile terminal can be a mobile phone, a tablet computer, a notebook computer and other network-connectable equipment. The sensor module is electrically connected with the front-end module, the front-end module is electrically connected with the monitoring host, the monitoring host is electrically connected with a router in the network module, the monitoring end is electrically connected with the router in the network module, and the mobile end is in wireless communication with the cloud server.

In this embodiment, the front end module 2 and the monitoring host 3 are arranged in the protective box, so that the front end module and the monitoring host are protected after being installed on the power equipment, and the service life of the front end module and the monitoring host is prolonged. In this embodiment, the front-end module includes a partial discharge signal acquisition circuit and a signal processing circuit, where the discharge signal acquisition circuit is configured to obtain a discharge signal, and the signal processing circuit processes the discharge signal.

In this embodiment, the sensor module 1 is installed on a GIS, which is a gas insulated switchgear, so that partial discharge of the equipment can be monitored. The UHF sensor is arranged at the position of the air chamber insulation isolator and is externally arranged. When GIS partial discharge occurs, UHF sensor receives the discharge signal radiated by disc insulator. The sensors are connected with the front end module through RG58 cables.

When the invention is applied to the GIS partial discharge on-line monitoring, a grounding wire of the GIS passes through the HFCT sensor, the UHFCT sensor is externally arranged and is arranged at the position of an insulating isolator of a gas chamber, and when partial discharge occurs, the UHFCT receives an electromagnetic wave signal radiated by a disc insulator.

After receiving the partial discharge signal, the multiple sensors perform identification according to the following steps:

the method comprises the steps of firstly, reserving partial discharge signals simultaneously extracted by multiple sensors, and discarding the partial discharge signals extracted by a single sensor. The specific judgment method is as follows: in the interval of [ t, t + delta t ], if more than half of the sensors detect the partial discharge signals, the partial discharge is considered to be really generated, otherwise, the detected partial discharge signals are considered to be the ambient environment interference. Wherein, t is the time recorded by the sensor which detects the partial discharge signal firstly, Δ t is the maximum time difference of the multiple sensors for detecting the same partial discharge signal, and Δ t is related to factors such as sensor type and cable length.

And step two, converting the partial discharge signals retained in the step one in a time domain and a frequency domain, calculating the equivalent time T and the equivalent frequency F of each pulse, projecting the equivalent time T and the equivalent frequency F to a 2-dimensional T-F plane, drawing a TF mapping chart, performing cluster analysis on the TF mapping chart, and separating the partial discharge signals according to the difference between noise clustering and partial discharge signal clustering. As a preferred scheme, the noise clusters and the partial discharge signal clusters are distinguished by the equivalent frequency, the noise clusters are formed when the frequency is lower, and the partial discharge signal clusters are formed when the frequency is higher. Fig. 3 is a typical TF map with clusters of partial discharge signals within the dashed box.

And step three, drawing the amplitude value, the extraction time and the power frequency voltage waveform of the partial discharge signal retained in the step two in the same graph, namely a PRPD spectrogram. Fig. 4 is a typical PRPD spectrum according to which partial discharge signals occurring in the second and fourth quadrants are discarded since partial discharge often occurs during the rise of the absolute value of the power frequency voltage.

And step four, amplifying the partial discharge signals screened in the step three by using an oscilloscope to completely present the waveforms, comparing the partial discharge signals with partial discharge standard waveforms (high-voltage end simple point discharge, grounding end point discharge, ungrounded conductor (protrusion) discharge, internal discharge, partial discharge (insulating paper or air bubbles), creeping discharge, thyristor interference, asynchronous signal interference and the like) defined by IEC 60270 through algorithms such as a convolutional neural network and a support vector machine, performing Fast Fourier Transform (FFT) on the partial discharge signals screened in the step three to obtain frequency spectrums of the partial discharge signals, and comprehensively judging the discharge types according to the time domain waveforms and the frequency spectrums.

While the invention has been described with reference to specific embodiments, the invention is not limited thereto, and various equivalent modifications and substitutions can be easily made by those skilled in the art within the technical scope of the invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims (10)

1. A partial discharge monitoring system based on multiple sensors is characterized by comprising a sensor module (1), a front-end module (2), a monitoring host (3), a network module (4), a mobile end (5) and a monitoring end (6), wherein the sensor module (1) is connected with the front-end module (2), the front-end module (2) is connected with the monitoring host (3), the monitoring host (3) is connected with the network module (4), and the mobile end (5) and the monitoring end (6) are respectively connected with the network module (4); the sensor module (1) is formed by at least two different types of sensors, and partial discharge signals received by the different types of sensors are mutually verified.

2. The multiple sensor-based partial discharge monitoring system of claim 1, wherein the different types of sensors include a high frequency current transformer HFCT (11), an ultra high frequency current transformer UHFCT (12), an instantaneous ground voltage sensor (13), and an ultrasonic sensor.

3. The multiple-sensor based partial discharge monitoring system of claim 2 wherein the high frequency current transformer HFCT is a Rogowski coil current sensor, and a high permeability magnetic core is used as a framework of the Rogowski coil.

4. The multiple sensor-based partial discharge monitoring system according to claim 2, wherein the sensor module (1) comprises a high frequency current transformer HFCT (11) and a very high frequency current transformer UHFCT (12).

5. The multiple-sensor based partial discharge monitoring system according to claim 1, wherein the front-end module (2) comprises a partial discharge signal acquisition circuit (21) and a partial discharge signal processing circuit (22) connected to each other; the partial discharge signal acquisition circuit (21) is connected with the sensor module (1), and the partial discharge signal processing circuit (22) is connected with the monitoring host (3);

the partial discharge signal acquisition circuit (21) is used for acquiring a partial discharge signal, and the partial discharge signal processing circuit (22) is used for processing the partial discharge signal.

6. The partial discharge monitoring system based on multiple sensors according to claim 1, wherein the network module (4) comprises a router (41) and a cloud server (42) connected to each other, the router (41) is connected to the monitoring host (3) and the monitoring terminal (6), respectively, and the cloud server (42) is connected to the mobile terminal (5).

7. The system for monitoring partial discharge based on multiple sensors according to claim 1, wherein the mobile terminal (5) is a mobile phone, a tablet computer or a notebook computer.

8. The partial discharge monitoring system based on multiple sensors according to claim 1, characterized in that the front-end module (2) and the monitoring host (3) are arranged in a protective box, and the sensor module (1) is connected with the front-end module (2) through RG58 cables.

9. A method for the multiple sensor based partial discharge monitoring system of claim 1, comprising the steps of:

step one, partial discharge signals extracted by multiple sensors at the same time are reserved, and partial discharge signals extracted by a single sensor are discarded;

step two, converting the partial discharge signals retained in the step one in a time domain and a frequency domain, calculating the equivalent time T and the equivalent frequency F of each pulse, projecting the equivalent time T and the equivalent frequency F to a 2-dimensional T-F plane, drawing a TF mapping chart, performing cluster analysis on the TF mapping chart, and separating the partial discharge signals according to the difference between noise clustering and the partial discharge signal clustering;

step three, drawing the amplitude value, the extraction time and the power frequency voltage waveform of the partial discharge signal retained in the step two in the same graph, namely a PRPD spectrogram, and discarding the partial discharge signals appearing in a second quadrant and a fourth quadrant according to the spectrogram;

and step four, amplifying the partial discharge signals screened out in the step three by using an oscilloscope to completely present the waveforms of the partial discharge signals, comparing the partial discharge signals with the partial discharge standard waveforms defined by IEC 60270 through a convolutional neural network or a support vector machine algorithm, performing fast Fourier transform on the partial discharge signals screened out in the step three to obtain frequency spectrums of the partial discharge signals, and comprehensively judging the discharge types according to the time domain waveforms and the frequency spectrums.

10. The method of claim 9, wherein the step one specific determination method is as follows: in the interval of [ t, t + delta t ], if more than half of the sensors detect partial discharge signals, the partial discharge is considered to be really generated, otherwise, the detected partial discharge signals are considered to be the ambient environment interference;

where t is the time recorded by the sensor that first detected the partial discharge signal, and Δ t is the maximum time difference between the multiple sensors detecting the same partial discharge signal.

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