EP3347727A1

EP3347727A1 - Method for locating partial discharges in an electrical apparatus, system for locating partial discharges and coupling housing

Info

Publication number: EP3347727A1
Application number: EP16769889.3A
Authority: EP
Inventors: Jean-François Penning; Assane SARR; Samuel FIFI
Original assignee: General Electric Technology GmbH
Current assignee: General Electric Technology GmbH
Priority date: 2015-09-08
Filing date: 2016-09-08
Publication date: 2018-07-18
Also published as: FR3040781B1; FR3040781A1; WO2017042261A1

Abstract

The invention relates to a method for locating a partial discharge in a high-voltage electrical apparatus (10) insulated by a dielectric fluid comprising at least one first and one second UHF sensor (11, 12). The method comprises the following steps: E1 recovering a first and a second signal, separating each of the first and second signals into at least two representative signals, combining the representative signals, calculating an interference function from the representative signals in the frequency range, and determining the location of the partial discharge from the calculated interference function. The invention further relates to a system for locating a partial discharge and a coupling housing occupying such a system.

Description

METHOD FOR LOCATING PARTIAL DISCHARGES IN AN ELECTRICAL EQUIPMENT, SYSTEM FOR LOCATING PARTIAL DISCHARGES, AND COUPLING HOUSING

DESCRIPTION

TECHNICAL AREA

The invention relates to the field of high voltage devices isolated by insulating fluids, such as electrical substations isolated by a dielectric gas, and methods for controlling these same electrical equipment.

STATE OF THE PRIOR ART In order to control the insulation state of a high-voltage electrical equipment, it is known to perform a detection of the presence of partial discharges.

Indeed, the existence of such partial discharges is characteristic of the presence of a defect of the apparatus which could cause in the short or medium term a failure. Partial discharge detection methods, such as that described in document EP 2726888 A1, are therefore used in the control of electrical equipment in order to detect such defects and are generally followed when such discharges are detected. an inspection of the equipment.

In order to facilitate and optimize this inspection, it is known, notably from the article by SM Hoek and his co-authors titled "New Procedures for Partial Discharge Localization in Gas-Insulated". Switchgears in Frequency and Time Domain "and published as part of the conference" XV ^th International Symposium on High Voltage Engineering "to Ljubljane Slovenia under the reference T7-547 to implement partial discharge localization processes.

Among the methods described by S. M. Hoek and his co-authors, a first method is termed location in the time domain. This method consists, as illustrated in FIGS. 1a and 1b, in equipping the high-voltage electrical equipment with at least a first and a second UHF sensor 11, 12 and measuring the representative signal 201, 202 of a partial discharge on each of these UHF sensors. The time offset Δt between the detection of the signal of a partial discharge on the first UHF sensor and the detection of the signal of this same partial discharge on the second sensor is directly related, as illustrated in Figure la, at the distance difference X2. -X1 of the first and second sensors 11, 12 vis-à-vis the location of the partial discharge 20 in the electrical equipment 10.

A simple calculation based on the speed of the UHF wave in the atmosphere of the electrical equipment makes it possible to go back to the distance difference X2-X1 and thus to the location of the partial discharge in the electrical equipment 10.

If this location method allows a simple location of the location of the electrical equipment 10 where partial discharges take place, it has a number of disadvantages. Indeed, it requires the use of an acquisition system additional fast, such as an oscilloscope, relatively expensive. This method is moreover strongly sensitive to any reflections of the partial discharge signal that may be produced by the non-straight portions of the electrical equipment 10. Thus, it is not uncommon for the calculation of the time offset Δt to be carried out in such a way that erroneous on one of these reflections and therefore that the location obtained is erroneous.

In order to solve these disadvantages S. M.

Hoek and his co-authors also describe a frequency domain detection method with interference measurement. This method is also based on the time shift between the signal of a partial discharge received on a first sensor 11 and a second sensor 12. In fact, the signals of a partial discharge 20 obtained from the first and the second sensor 11, 12 can be considered substantially identical with a corresponding phase shift At offset, it is possible to calculate a function of interference between these two signals to determine this shift.

This interference function can be expressed mathematically as follows:

with K (w) the interference function in the frequency domain, H (w) the spectrum of the sum of the first and second signals, G (w) and F (w) respectively the spectra of the first and second signals. Thus, considering that the signals of the first and second are substantially identical out of phase with the time offset At, it is possible to approximate the following equality:

The interference function can therefore be approximated in the frequency domain by a function

2π

rectified cosine of period Αω = - that can be

To express in terms of frequency: Af = -

Has

In practice and because of measurement errors, noise and inaccuracy of the approximations used, the interference function, although periodic, moves away from the idealized form of the rectified cosine. S. M. Hoek and his co-authors show that a wavelet transform of the interference function in the frequency domain makes it possible to measure a "fundamental frequency" of the interference function and thus to determine the time shift At.

Thus, such a method in the frequency domain with calculation of an interference function makes it possible to obtain a measurement of the time offset At, and thus to determine the location of the partial discharges, in a robust manner and not influenced by any possible However, this method in the frequency domain also has certain disadvantages.

Indeed, it is relatively complex to put in place since it requires three measures successive first and second measurements of the partial discharge signal on the first and second UHF sensors 11, 12 respectively and a third measurement in which the first and second discharge signals are combined. With such conditions, the measurements of the first and second signals respectively measured on the first and second sensors 11, 12 and the sum signal of these first and second signals are performed with a shift in time. There may therefore be a discrepancy between these different measurements which makes the equality approximation between the first and second signals inaccurate, which can create disturbances in the calculated interference function. Thus, this method is relatively complex to implement, because of the need to perform three successive measurements and provides results that can be difficult to interpret even through a wavelet transform. STATEMENT OF THE INVENTION

The aim of the invention is to remedy at least partially these drawbacks and is thus intended to provide a method for locating partial discharges in high-voltage electrical equipment isolated by a dielectric fluid that is both robust and therefore insensitive to possible reflections of partial discharge signals in the electrical equipment, and which is simplified compared to the method of locating a partial discharge in the frequency domain of the prior art. To this end, the invention relates to a method for locating a partial discharge in high voltage electrical equipment isolated by a dielectric fluid comprising at least a first and a second UHF sensor, said method comprising the following steps:

El recovery of a first and a second signal respectively from the first and the second UHF sensor,

E2 separating each of the first and second signals into at least two representative signals on at least two respective channels,

E3 combining representative signals to provide a sum signal representative of the sum of the first and second signals,

E4 parallel acquisition of the representative signals and the sum signal,

E5 calculating an interference function from the representative signals and the acquired sum signal, this calculation consisting in dividing the spectrum of the sum signal by the sum of the spectra of the representative signals,

E6 determination of the location of the partial discharge from the calculated interference function.

Such a method allows a location of the partial discharge robust and unaffected by any disturbances. Indeed, the first and the second representative signal and the sum signal being acquired simultaneously, the equality approximation between the first and the second representative signal when calculating the interference function is checked. Thus, the determination of the time shift from the interference function is facilitated even in a disturbed environment, all the more so when it is implemented using a wavelet transform.

In addition, the acquisition of the first and the second signal, through the signals representative of the separation devices, and the sum signal being performed simultaneously, this limits the number of successive connection operations to be performed by a technician setting implement the process. The method is thus simplified with respect to a method for locating a partial discharge of the prior art.

By signal representative of a first signal it should be understood that the representative signal has a proportionality link with respect to the first signal at least according to one of its variables, such as voltage, current or power. Thus, in a conventional configuration of the invention, a representative signal has a power equal to a predetermined fraction of said first signal, for example half or third, it being understood that this does not exclude that the power of the representative signal can be equal to the power of said first signal or even be equal to a multiple of this same power. The determining step may comprise a sub-step of performing a wavelet transform.

Such a sub-step is particularly suitable for allowing the determination of the time shift from the interference function even when the UHF signals are noisy. A particularly robust localization method is thus obtained.

The invention further relates to a system for locating a partial discharge in high voltage electrical equipment isolated by a dielectric fluid, said electrical apparatus comprising at least a first and a second UHF sensor,

the location system comprising:

at least a first and a second input connector intended to be respectively connected to the first and second UHF sensors and adapted to respectively recover a first and a second signal respectively from the first and second UHF sensors,

at least a first and a second separation device respectively connected to the first and second input connectors and adapted to respectively share the first and second signals in at least two representative signals on at least two respective channels,

at least one coupling device connected to the first and second separation devices and adapted to combine the representative signals so as to provide a sum signal representative of the sum of the first and the second signal,

at least one acquisition device connected to the first and second separation devices and to the coupling device and adapted to acquire the representative signals and the sum signal in parallel,

an analysis unit connected to the acquisition system and configured to perform a calculation of an interference function from the representative signals and the sum signal, said calculation of dividing the spectrum of the sum signal by the sum of the spectra of the signals representative of the first and second signals,

said analysis unit being further configured to allow determination of the location of the partial discharge from the calculated interference function.

Such a locating system makes it possible to implement a method of locating a partial discharge according to the invention and thus benefits from this process.

According to a first possibility of the invention, the locating system may comprise a coupling box, said coupling box comprising the first and the second input connector, the first and the second separation device, and the coupling device, said coupling housing having a first, a second and a third output connector respectively connected to the first and second separating device and to the coupling device, said first, second and third output connectors being connected to the at least one acquisition device.

A location system including such a coupling box is particularly suitable for providing a portable location system that can be connected to ready UHF sensors installed on the electrical equipment. Thus the technician is able to come on the spot to take measurements.

According to another possibility of the invention, the locating system may comprise at least a first and a second coupling unit,

the first coupling housing having the first input connector and a third input connector connected to the second coupling housing, a first and a third output connector,

the second coupling housing comprising at least the second input connector, a second output connector and a fourth output connector through which the second coupling housing is connected to the third input connector of the first coupling housing.

the first and the second coupling housing respectively comprising the first and the second separating device, the first and the second separating device being respectively connected to the first and second output connectors,

the first coupling unit further comprising the coupling device connected to the first separation device and the third connector input, the latter being connected to the fourth output connector of the second coupling housing, the sum signal being supplied through the third output connector,

the second separation device being connected to the fourth output connector,

the first, second and third output connectors being connected to the at least one acquisition device.

With such coupling boxes, the system is particularly suitable for permanent installation in electrical equipment. Indeed, it is possible to deploy these coupling boxes in the electrical equipment so as to cover its entire length. In this way, a technician wanting to locate a partial discharge occurring in the electrical equipment just has to connect the acquisition device to the different coupling boxes of the electrical equipment. In this configuration, each of the coupling boxes then serves in turn first and second coupling housing in the sense of the invention.

The first and the second coupling box may be identical.

The acquisition device may comprise at least a first and a second acquisition module, the first channels of the first and second separation device being respectively connected to the first and second acquisition module and in which the coupling device is connected to the first acquisition module, each of the first and second acquisition modules being connected, or intended to be connected, to the analysis unit.

With such a configuration, the system can be permanently integrated into the electrical equipment with an acquisition module for each of the UHF sensors. Such a system can therefore easily be adapted to perform the method of locating a partial discharge at a distance without requiring the movement of a technician. It will be noted moreover that with such a configuration, the number of acquisition module is optimized.

The locating system may comprise high voltage electrical equipment isolated by a dielectric fluid,

the first and the second input connector, the first and the second separation device and the coupling device being integrated into the electrical equipment with the first and second input connectors connected respectively to the first and second sensors UHF, the electrical equipment comprising at least a first and a second output connector respectively connected to the first and second separation device, and a third output connector connected to the coupling device.

the acquisition device and the analysis unit can be provided by at least one acquisition and analysis module independent of the high-voltage electrical equipment isolated by a dielectric fluid, said acquisition module and analysis system comprising a first, a second and a third connector respectively connected to the first, second and third input connector.

With such a configuration, the system can be partially integrated into the electrical equipment, the technician can intervene with a portable acquisition and analysis module to implement the method of locating a partial discharge, or intervene remotely if the system is connected to a remote computer via a computer network.

The first and the second separation device can each be a divider,

the coupling device may be an inverted mixer or divider mounted.

The invention also relates to a coupling box for a system according to the invention, said coupling box comprising:

a first and a second input connector intended to be respectively connected to a first and second UHF sensor of a high voltage electrical equipment isolated by a dielectric fluid, and adapted to respectively recover a first and a second signal respectively from the first and second UHF sensor,

a first and a second separation device respectively connected to the first and second input connectors and adapted to respectively separate the first and second signals into two representative signals on at least two respective channels, at least one coupling device connected to the first and second separation devices and adapted to combine the representative signals so as to provide a sum signal representative of the sum of the first and second signals,

a first, a second and a third output connector respectively connected to the first and second separation devices and to the coupling device, said first, second and third output connectors being intended to be connected to at least one connected acquisition device; to an analysis unit for forming a location system according to the invention.

Such a coupling box is particularly adapted to equip a portable discharge location system. Thus, a technician having to implement a method of locating a partial discharge can do so on an apparatus simply equipped with UHF sensor by connecting the connected coupling unit a portable acquisition and analysis module with two UHF sensors. sequence between which a partial discharge is likely to exist.

The invention further relates to a coupling housing for a locating system according to the invention comprising:

a first input socket for forming the first input connector of the location system, said first input socket being adapted to recover a first signal from the first UHF sensor,

a second input socket for forming the third input connector and for being connected to a substantially identical second coupling housing, said second coupling housing having its first input socket connected to a second UHF sensor so that it forms the second input connector of the location system,

a separation device connected to the first input socket and adapted to separate the first signal into three representative signals on three respective channels,

a coupling device connected to the separation device and to the second input socket and adapted to combine the representative signal and the signal supplied by the second coupling unit so as to provide a sum signal representative of the sum of the first signal and the second signal,

a first and a second output respectively connected to the first separation device,

a third output socket by which the signal sum is supplied,

the second and third output sockets being intended to respectively form the first and third output connectors and to be connected to at least one acquisition device which is itself connected to an analysis unit so as to form with the second coupling unit a location system according to the invention.

Such coupling boxes are particularly suitable for permanent installation in electrical equipment by equipping each of the UHF sensors of the electrical equipment. Thus, further providing in the same electrical equipment an acquisition module fitted to each of the coupling boxes and an analysis unit, it is possible to provide a partial discharge location system that can be controlled remotely.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be better understood on reading the description of exemplary embodiments, given purely by way of indication and in no way limiting, with reference to the appended drawings in which:

FIGS. 1a and 1b respectively illustrate an electrical equipment isolated by a dielectric fluid equipped with a first and a second UHF sensor in which electrical equipment takes place a partial discharge to be located and the measurements of the signal of a partial discharge obtained on the first and the second UHF sensor,

FIG. 2 illustrates a high voltage electrical equipment isolated by dielectric fluid comprising three phases each equipped with a first and a second UHF sensor, and a partial discharge location system equipping one of the phases of said electrical equipment, FIG. 3 illustrates a coupling unit equipping the positioning system illustrated in FIG. 2 with part of its wall torn off to illustrate a first and a second separation device and a coupling device,

FIG. 4 is a flowchart illustrating the main steps and sub-steps of a method for locating partial discharges according to the invention,

FIG. 5 illustrates an example of the signals acquired by an acquisition unit as illustrated in FIG. 3 with, respectively, at A, B and C, the signals acquired from a first and a second UHF sensor of FIG. electrical equipment and a sum signal, these same signals seen in the frequency domain, respectively D, E and F, and an interference function G in the frequency domain calculated from these same signals,

FIGS. 6a and 6b illustrate an example of interference function respectively in the frequency domain and after wavelet transform of the family of "cosine-rectified" wavelets,

FIG. 7 illustrates an electrical apparatus forming part of a locating system according to a second embodiment of the invention, said electrical equipment comprising several UHF sensors equipped to enable the partial discharge to be located, FIG. 8 illustrates a coupling box adapted to equip an electrical apparatus according to the second embodiment,

FIG. 9 illustrates a coupling box adapted to equip an electrical apparatus according to the second embodiment, this coupling box being specific to the first UHF sensor of said apparatus,

FIG. 10 illustrates the connection between them of the coupling casings of the location system according to the second embodiment, the first and the last coupling casing not being specific and being equipped with 50-ohm end plugs,

- Figure 11 illustrates the connection of two successive coupling boxes according to the second embodiment.

The different parts shown in the figures are not necessarily in a uniform scale, to make the figures more readable.

The different possibilities (variants and embodiments) must be understood as not being exclusive of each other and can be combined with one another.

DETAILED PRESENTATION OF PARTICULAR EMBODIMENTS

FIG. 2 illustrates a high-voltage electrical apparatus 10 comprising three phases each equipped with a first and a second UHF sensor 11, 12, such as UHF antennas. The phase of the electrical equipment 10 furthest from the foreground presents its first and second UHF sensors 11, 12 connected to a partial discharge location system 100 according to the invention in order to allow the detection of a partial discharge.

The locating system 100 comprises: a coupling housing 20 to which are connected the first and second UHF sensors 11, 12, an acquisition device 30 connected to the coupling housing 20, and

a computer 40 connected to the acquisition device 30.

The coupling housing 20, as illustrated in FIG. 3, comprises:

a first and a second input connector 21, 22 respectively connected to the first and second UHF sensors 11, 12,

a first and a second power divider 23, 24, also known as a separator, each connected respectively to the first and second input connectors 21, 22 and comprising a first and a second channel,

a mixer 25, also known under the name of a coupler connected at input to the second channels of the first and second divider 23, 24, a first, second and third output connector 26, 27, 28 respectively connected to the first channels of the first and second channels; second divider

23, 24 and at the outlet of the mixer 25.

The first and second divisors 23, 24 are both adapted to separate respectively the first and second signals in two representative signals on their respective first and second paths. Thus the first and the second divider 23, 24 each form a separation device adapted to separate respectively the first and the second signal into two representative signals on at least two respective channels.

In the configuration of the coupling box 20 illustrated in FIG. 3, the first and second dividers 23, 24 are adapted to respectively separate the first and second signals into two respective representative signals whose power corresponds to the power of the corresponding divided signal. by two. Such dividers 23, 24 have, among other things, the advantage of being passive components that do not require additional power supply. Of course, the coupling housing 20 may comprise another type of separation device without departing from the scope of the invention.

Thus, the coupling housing 20 may also comprise, in substitution for the first and second divider 23, 24, a first and a second active component, that is to say supplied either by an external power supply, or by an internal power supply, adapted to provide on each of their first and second channels a representative signal substantially equal to the corresponding signal.

The mixer 25 allows to combine the representative signals from the second channels of the first and second divider 23, 24 and outputs a signal sum corresponding to the sum of the signals representative of the first and second signals. The mixer 25 thus forms a coupling device connected to the first and second dividers 23, 24 and adapted to combine the representative signals so as to provide a sum signal representative of the sum of the first and second signals. It may be noted that, as a variant of the invention, the coupling device may also be formed by an inverted mounted divider, the first and second representative signals being then injected by the two outputs of the divider and the input of the divider serving as the exit.

Such a mixer 25 has the further advantage of being a passive component and thus allows, with the first and the second divider, to provide a fully passive coupling box 20. Of course, it is also conceivable, without departing from the scope of the invention, the coupling housing 20 comprises a coupling device other than a mixer, the latter may be passive or active, without the we leave the scope of the invention.

With such a configuration of the coupling housing 20, when the latter is connected by its first and second input connector 21, 22 to the first and second UHF sensor 11, 12, the first, the second and the third output connector 26 , 27, 28 show signals respectively representative of the first and second signals and the sum of the first and second signals.

The first, the second and the third output connectors 26, 27, 28 are all three connected to the acquisition device 30. The acquisition device 30 is adapted to acquire from the output connectors 26, 27, 28 of the coupling unit 20 the signals representative of the first and second signals and the sum of the first and second signals. the second signal. Acquisition of signals representative of the first and second signals and the sum of the first and second signals can be done directly in the frequency domain, or in the time domain, with a Fourier transform to obtain the spectrum of these signals.

The acquisition device 30 illustrated in FIG. 2 is an acquisition device as described in document EP 2726888 A1 in which it is called a control device and illustrated in FIG. 3 of this document, comprising three acquisition channels. . It should be noted that, contrary to the invention, the three acquisition paths of this acquisition device are provided in this document to acquire the signals on the 3 phases of the high voltage switchgear.

Thus, as described in document EP 2726888 A1, the acquisition device 30, according to the block diagram of FIG. 3 of this document, not reproduced here, comprises:

- a housing,

three connection terminals to a sensor respectively connected to the first, second and third inputs 26, 27, 28 of the coupling housing 20,

a computer socket for connecting the computer 40, and a grounding plug to ensure the security of the control device,

- three UHF protection systems whose inputs are each connected to one of the connection terminals,

- three UHF tuners (or tuners) whose inputs are each connected to the output of one of the UHF protection systems,

three analog / digital converters (or ADCs) whose inputs are each connected to the output of one of the UHF tuners so as to convert the signals from the corresponding UHF tuner into a digital signal,

a system for acquiring a synchronization voltage, the input of which is connected to the synchronization terminal,

three processing units (or μΡ) synchronized by the acquisition system of a synchronization voltage and each adapted to process the digital signals from an analog / digital converter, also synchronized by the acquisition system,

a connection module (or COM) to a computer, said connection module being adapted to interface between the processing units and the computer 40, and being connected to the computer socket of the control device.

Such an acquisition device 30 has the advantage of allowing both the detection of a partial discharge in the electrical equipment, as described in document EP 2726888 A1, and the acquisition of a frequency spectrum. It thus makes it possible to acquire the signals representing respectively the first and the second signal and the sum of the first and second signals in the frequency domain.

Of course, the acquisition device 30 may be other than the acquisition device described in EP 2726888 A1 without departing from the scope of the invention. In this context, the acquisition device 30 may comprise one or more oscillators adapted to operate in the frequency range of the UHF, or one to several acquisition cards equipping the computer 40, where said cards being adapted to allow an acquisition of signals representative of the first and second signals and the sum of the first and second signals directly in the frequency domain, or in the time domain, with a Fourier transform to obtain the spectrum of these signals.

The acquisition device 30 is itself connected to the computer 40 so as to transmit the signals acquired to the latter.

The computer 40 is configured to, from the signals acquired by the acquisition device 30, calculate an interference function.

The acquisition device 30 and the computer 40 together form an acquisition and analysis module.

Such an interference function, as described in the article by SM Hoek and his co-authors and described above in the introductory part relating to the prior art, can be calculated by following equation (1):

with K (w) the interference function in the frequency domain, H (w) the spectrum of the signal representative of the sum of the first and the second signals, G (w) and F (w) the spectra of the signals respectively representative of the first and second signal.

Thus, in the case where the acquisition of the signals representative of the first and second signals and their sum by the acquisition device 30 is performed in the time domain, the computer 40 is configured to perform a Fourier transform of these representative signals to obtain these representative signals in the frequency domain.

The signals representative of the first and second signals and their sum are therefore available to the computer 40, either by calculation or directly provided by the acquisition device 30, the computer 40 is configured to calculate the function of interference according to equation (1) above.

The computer 40 is also configured to allow, from the calculated interference function, a determination of the location of the partial discharge.

Indeed, as shown by SM Hoek and his co-authors in their article and as indicated in the part of the prior art, the interference equation can be approximated in the frequency domain to a rectified cosine whose "frequency" period Af is equal to the inverse of the time offset At (see equation (2)). It is therefore sufficient to determine the period of the interference function to deduce, from the speed of an electromagnetic wave in the electrical equipment, a differential X2-X1 of the distance from the location where the discharge takes place. partial between the first and the second UHF sensor. Such a differential then makes it easy to deduce precisely the location of the partial discharge and perform the necessary inspection operations.

According to an advantageous possibility of the invention, in order to allow the determination of the period of the interference function in the frequency domain, the computer can be adapted to perform on the interference function a wavelet transform on the basis of the family of corrected cosine wavelets.

A wavelet of this family can be written according to the following equation:

Thus, a wavelet transform consists of performing the following calculation

with K _S , _T (w) a wavelet of the wavelet family of the rectified cosine type, * the conjugate complex, τ the translation factor and s the expansion factor. This calculation makes it possible to obtain a correlation graph from which it is possible to determine the wavelet for which the correlation is maximal. The expansion factor of said wavelet exhibiting the maximum correlation corresponds to Af which is equal to the inverse of the desired time shift At.

According to different variants of the invention, the computer may be configured to determine this correlation maximum and the associated time offset, or may be configured to display the correlation graph so that a technician determines on this graph the corresponding dilation factor. and therefore the corresponding time shift.

This second solution is to be preferred, since it allows the technician using the detection system to check on the correlation graph, the proper implementation of the detection method.

With this configuration of the computer 40 for calculating the interference function and making it possible, from said interference function, to determine the location in the electrical equipment 10 of the partial discharge, the computer forms a communication unit. analysis according to the invention. Such an analysis unit is thus configured to perform a calculation of an interference function from the signals representative of the first and second signals and of the sum signal, this calculation consisting of dividing the spectrum of the sum signal by the sum of the spectra. signals representative of the first and second signals. Said analysis unit is further configured to determine the location of the partial discharge from the calculated interference function.

Such a system 100 of a partial discharge allows the implementation of a method of locating a partial discharge. Such a partial discharge location method comprises, as illustrated in the flow chart of FIG. 4, the following steps:

El recovery of a first and a second signal respectively from the first and second UHF sensors 11, 12,

E2 separating each of the first and second signals into at least two representative signals on two respective channels,

- E3 combination of the representative signals so as to provide a sum signal representative of the sum of the first and the second signal,

E4 parallel acquisition of the representative signals and the sum signal,

E5 calculating an interference function from the signals representative of the first channels and the acquired sum signal, this calculation consisting in dividing the spectrum of the sum signal by the sum of the spectra of the signals representative of the first channels,

In such a method, the acquisition of the representative signals is carried out during step E4 through the first channels of the dividers 23, 24, while the coupling of the representative signals provided through the second channels of the dividers 23, 24 is performed in the step E3.

The steps E1-E3 are implemented by means of the coupling box 20, while the step E4 and the steps E5 and E6 are respectively implemented by means of the acquisition device 30 and the computer 40.

According to the possibility illustrated on the flowchart of FIG. 4, the step of determining the location of the partial discharge comprises the following sub-steps:

E61 performing a wavelet transform of the interference function according to the family of corrected cosine wavelets,

- E62 determination, from the result of the wavelet transform, the location of the partial discharge in the electrical equipment, such a determination can be obtained by calculating from the correlation maximum the time offset At between the signals of the first and second UHF sensors 11, 12.

Of course, if the substep E61 is implemented by means of the computer 40, the substep E62 can be performed manually by a technician, using the assistance or not the computer 40, or by the computer in an automated way.

In the first case, the substep E62 can consist in carrying out the following operations: graphical display on the computer screen of the result of the wavelet transform of the interference function,

selection by the technician on the displayed graph of the maximum correlation and determination from this maximum of the corresponding time offset At,

determination and display by the computer 40 of the difference in distance X2-X1 of the location of the partial discharge with respect to the first and second UHF sensors 11, 12.

FIGS. 5, 6a and 6b illustrate the results of each of these steps of such a method when locating a partial discharge in an isolated electrical station by a dielectric fluid, such as, for example, sulfur hexafluoride gas.

Thus, FIG. 5 illustrates at A and B, respectively, the signal captured by means of the acquisition device 30 from the first and second UHF sensors 11, 12, and represented in the time domain. It can be seen from these two graphs that the signal on the second sensor 12 is delayed by about 13.4 ns. In C of this same figure is illustrated the signal sum corresponding to the sum of the signal of the first and the second UHF sensor 11, 12. In D, E and F of FIG. 5 are respectively illustrated the spectrum of the signals illustrated respectively in A, B, C of Figure 5.

These three spectra D, E and F are acquired directly in the frequency domain and correspond to the signals represented in FIG. 5 A, B, C in the time domain. These three spectra are used to determine the interference function illustrated in FIG. 5G in the frequency domain. It may be noted that, alternatively, according to a possibility of the invention, these signals can be acquired in the time domain and then transposed in the frequency domain by a Fourier transform by means of the computer 40.

FIG. 6a illustrates this example of an interference function 203 connected in parallel with a rectified cosine 204 whose "frequency" period Af is equal to the inverse of the time offset Δt between the first and the second signal (see in this connection). equation (2) described in the preamble of this document). The simple paralleling of these signals does not confirm the good correlation between the two.

Figure 6b illustrates the result of the wavelet transform of the interference function of Figure 6a. It is observed in the graph of FIG. 6b that while FIG. 6a does not show a clear correlation between the interference function 203 and the rectified cosine 204, this correlation is perfectly proved by the wavelet transform. Passing through a wavelet transform makes it possible to overcome the disturbances that affect the interference function and to provide a robust localization method.

Thus, with a correlation centered at 75 MHz for the expansion factor and 600 MHz for the translation factor, the corresponding time offset At is 13.4ns, that is to say a difference in distance from the first and second UHF sensor of about 4m.

According to a second embodiment of a rental system of a partial discharge according to the invention partially illustrated in Figure 7, the electrical equipment 1010 may at least partly be pre-equipped to allow such a location.

Such a locating system differs from a locating system 100 according to the first embodiment in that the functions performed by the coupling box and the acquisition device are permanently installed in the electrical equipment 1010, the system detection device according to this embodiment comprising the electrical equipment 1010.

The electrical apparatus 1010 according to this second embodiment comprises:

at least two UHF sensors 1011, 1012 ..., 101η, the electrical equipment 1010 illustrated in FIG. 7 comprising n UHF sensors 1011, 1012 ..., 101η on each of its three phases,

a divider 1021, 1022 ..., 102n, for each of the UHF sensors 1011, 1012 ..., 101η except the last, comprising a first, a second and a third channel, only the dividers 1021, 1022 .. ., 102n of the phase closest to the first plane of the drawing being shown in FIG. 7, the divider 1021 corresponding to the first UHF sensor 1011 having only first and second channels, each of the dividers 1021, 1022 ... , 102n being connected to the corresponding UHF sensor 1011, 1012 ..., 101η and being adapted to provide on each of their first, second and third channels a signal representative of the corresponding UHF sensor signal 1011, 1012 ..., 101η,

a mixer 1031, 1032 ..., 103n for each of the UHF sensors 1011, 1012 ..., 101η except the last, each mixer 1031, 1032 ..., 103n being connected to two dividers 1021, 1022 .. ., 102n succeeding one another, said mixer 1031, 1032 ..., 103n being connected to the third channel of the first and second channels of the second and being adapted to supply a signal representative of the sum of the signals of the UHF sensors 1011, 1012 ..., 101η corresponding to two successive divisors 1021, 1022 ..., 102n,

an acquisition module 1041, 1042 ..., 104n corresponding to each of the UHF sensors 1011, 1012 ..., 101η, said acquisition module 1041, 1042 ..., 104n being connected to the second channel of the divider 1021 , 1022 ..., 102n corresponding to said UHF sensor 1011, 1012 ..., 101η and except the latter to the mixer 1031, 1032 ... 103n, connected itself to said divider 1021, 1022 ..., 102 (n-1) and the divisor 1022, 1023 ..., 102n succeeding it.

The last UHF sensor 101η, like the first UHF sensor, has a particular configuration. Thus, no mixer corresponds to it and the corresponding divider 102n has only a first and a second channel, the first channel being connected to the mixer 103n-1, of the UHF sensor 101n-1 which precedes the last UHF sensor 101η, and the second channel being connected to the acquisition module 104n, corresponding to the latter UHF sensor 10n.

Acquisition modules 1041, 1042 ..., 104n are of the same type as that described in document EP 2726888 A1 and in the first embodiment, with the difference that they comprise six input connectors, ie one pair phase input connectors of the electrical equipment 1010, and six acquisition channels of a signal each corresponding to a respective input connector so as to allow acquisition of the UHF signal injected by said channel.

For each pair of input connectors, there is a first input connector for the corresponding UHF sensor signal acquired by the corresponding second divider channel (first channel for that of the first UHF sensor) and a second input connector. for the sum signal supplied by the mixer corresponding to said UHF sensor.

The acquisition modules 1041, 1042 ..., 104n are illustrated in FIG. 7 only connected to the UHF sensors 1011, 1012 ..., 101η of one of the phases of the electrical equipment 1010. Of course, in the As part of a conventional configuration of the locating system according to this second embodiment, the UHF sensors of the other phases of the electrical equipment 1010 are also connected via dividers and mixers to acquisition modules 1041, 1042 ..., 104n, these acquisition modules can be the same as those used for the first phase or other acquisition modules. Acquisition modules 1041, 1042 ..., 104n are each connected to the computer, not shown in FIG. 7, by a computer link. Such a computer link may be a direct link, wired or wireless, in the case where the computer is installed on site, or a link provided by a private or public computer network for a remote computer.

Thus, with a configuration according to this second embodiment, it is possible to perform a first test of the electrical equipment 1010 to detect the presence of a partial discharge on one of the phases of the electrical equipment, for example according to the method described in EP 2726888 A1 and to precisely locate this partial discharge according to a principle similar to that described in the first embodiment.

It should be noted that in order to locate a partial discharge identified as present between a UHF sensor m and a UHF sensor m + 1 succeeding it directly, the signals representative of the UHF sensor signal m and the sum of the signals UHF sensors m and m + 1 are acquired by means of the acquisition module corresponding to the UHF sensor m whereas the signal representative of the signal of the UHF sensor m + 1 is acquired by means of the acquisition module corresponding to the UHF sensor m + 1.

Such a configuration makes it possible to limit the number of acquisition modules required. Indeed, a module for acquiring a UHF sensor m will be used both to determine the position of a partial discharge between UHF sensors m-1 and m and between UHF sensors m and m + 1. According to this second embodiment, the mixers 1021, 1022 ... and the dividers of the electrical equipment can be arranged in a housing so as to form a coupling housing 2020a as illustrated in FIG. coupling 2020a is referenced in correspondence with the UHF sensor 1012 of FIG. 7, the divider 2023 and the mixer 2024 corresponding respectively, as indicated by their double reference, to the divider 1022 and to the mixer 1032.

Such a coupling unit 2020a comprises: a first and a second input socket 2021, 2022 intended to be respectively connected to the corresponding UHF sensor 1012 and the divider 1023 corresponding to the UHF sensor 1013 which directly succeeds the UHF sensor 1012 corresponding to the housing of 2020a coupling,

the divider 2023 connected to the first input socket 2021, the divider comprising a first, a second and a third channel,

the mixer 2024 connected to the third channel of the divider 2023 and to the second input socket 2022,

first, second and third output jacks 2025, 2026, 2027 respectively connected to the first and second channels of the divider 2023 and to the mixer 2024.

The first output socket is intended to be connected to the input of the mixer 1031 corresponding to the UHF sensor 1011 that the UHF sensor 1012 corresponding to the coupling unit 2020a succeeds directly. The second and third output jacks are connected to the acquisition module 1042 of the corresponding UHF sensor 1012 in order to enable the latter to acquire the signal representative of the corresponding UHF sensor signal 1012 and the signal representative of the sum of the sensor signal. Corresponding UHF 1012 and the UHF 1013 sensor which succeeds it directly.

The "plug" and "connector" terminologies used above and throughout the rest of this document are purely synonymous and interchangeable. These two different terminologies are used solely for the purpose of differentiating the denomination of the plugs of the coupling units of this second embodiment of the connectors of the locating system formed by these coupling units. It can thus be noted that these terminologies must be included in their widest definition, these having to include any type of connection making it possible to provide an electrical connection. Thus the terms of connectors or sockets may for example cover, according to certain variants of the invention, solder contacts.

The coupling housing 2020b corresponding to the first UHF sensor 1011, as illustrated in FIG. 9, differs from the coupling housing illustrated in FIG. 8 in that:

the divider 2023b has only a first and a second channel, the mixer 2024 is connected to the second channel of the divider 2023b,

the coupling unit 2020b has only first and second output jacks 2026, 2027 respectively connected to the first channel of the divider 2023b and to the mixer 2024.

In the same way, the coupling housing, not illustrated, of the last UHF sensor 101η differs from a coupling housing illustrated in FIG. 8 in that it comprises:

a single divider comprising only a first and a second channel, and

a first and a second output respectively connected to the first and second channels of the divider.

It may be noted that in order to equip the electrical apparatus with only one type of coupling housing, the coupling boxes corresponding to the first and the last UHF sensor 1011 may be of the same type as that illustrated in FIG. Figure 10 illustrates the connection of the coupling boxes to each other in such a configuration.

In the case of the first UHF sensor 1011, only the second and third output jacks 2026, 2027 of the corresponding coupling unit are connected, the first output junction 2025 remaining free and preferably being closed by an impedance terminating plug 2028. characteristic 50 Ohms. In the case of the last UHF sensor, the second input jack 2022 and the third output jack 2027 are not connected and are preferably closed by a terminator plug 2028, characteristic impedance 50 Ohms.

Thus, with such coupling boxes succeeding each other in the electrical equipment, taking again the example presented above concerning a UHF sensor m and a UHF sensor m + 1, it is possible to define a partial discharge location system between the sensor m and the sensor m + 1.

A location system thus defined comprises a first coupling housing, that of the UHF sensor m, and a second coupling housing, that of the UHF sensor m + 1. This locating system, exemplified in FIG. 11, conforms to that according to the second embodiment with, with reference to the coupling housing illustrated in FIG. 8:

the first coupling unit 2020a (that corresponding to the UHF sensor m) which comprises the first input connector formed by the first input socket 2021, and a third input connector formed by the second input socket 2022 connected to the second coupling housing 2020a (corresponding to the UHF sensor m + 1), the first and third output connectors, respectively the second and third output jacks 2026, 2027,

the second coupling unit 2020a which comprises at least the second input connector, formed by its first input socket 2021, the second output connector, formed by its second output socket 2026 and a fourth output connector, its first output socket 2025, by which the second coupling box 2020a is connected to the third input connector which is formed by the second input jack 2022 of the first coupling housing.

The first and the second coupling housing 2020a also comprises respectively the first and the second separator 2023, the first channels of the first and second separator 2023 being respectively connected to the first and the second output connector 2026, that is to say say the respective second outlet 2026 of the first and second coupling housing (those UHF sensors m and m + 1).

The first coupling unit 2020a further comprises the mixer 2024 connected to the second channel of the first splitter 2023 and the third input connector 2022, that is to say the second input terminal, the latter being connected to the fourth connector of output 2025, i.e. the first output socket of the second coupling housing 2020a, the sum signal being supplied through the third output connector, i.e. the third output socket 2027 of the first coupling housing 2020a. The second path of the second separation device is connected to the fourth output connector 2025, i.e. the first output socket of the second coupling housing.

In this way, the signals representative of the UHF sensor m and the sum of the signals of the UHF sensor m and the UHF sensor m + 1 are respectively available on the first and the third output connector 2026, 2027 corresponding to the second and third taps. first exit coupling box 2020a (that corresponding to this UHF sensor m) and which are connected to the acquisition module of the UHF sensor m.

The signal representative of the sensor m + 1 is therefore available on the second output connector 2026 corresponding to the second output socket of the second coupling unit 2020a (that corresponding to the UHF sensor m + 1) which is connected to the acquisition module of the UHF sensor m + 1.

Such a second embodiment allows a location of partial discharges at a distance, that is to say, without the intervention of a person at the level of the electrical equipment, provided that the system formed by the housings of acquisition 1041, 1042 ..., 104n and the computer is connected to a remote computer via a computer network. In this case, the step of determining the location of the partial discharge can, as in the first embodiment, be carried out manually by a technician from a remote computer, using the assistance or not of the computer, or by the computer. computer in an automated way.

If in the second embodiment described above, the electrical equipment 1010 comprises an acquisition module 1041, 1042 ..., 104n for each of the UHF sensors 1011, 1012, 1013 ..., 101η, it is also it is conceivable, without departing from the scope of the invention, to connect one or more acquisition modules only when testing the electrical equipment. According to this possibility, hybrid between the first and the second embodiment and not illustrated, the electrical equipment is pre-equipped in a mixer and divider to obtain for each pair of UHF sensors succeeding each other the signals representative of each of the signals of these two UHF sensors and their sum, the acquisition being obtained by connecting an external acquisition box as shown in Figure 2.

Claims

A method of locating a partial discharge in high voltage electrical equipment (10, 1010) isolated by a dielectric fluid having at least a first and a second UHF sensor (11, 12, 1011, 1012, 1013 ..., 101η), said method being characterized in that it comprises the following steps:

(El) recovering a first and a second signal respectively from the first and second UHF sensors (11, 12, 1011, 1012, 1013 ..., 101η),

(E2) separating each of the first and second signals into at least two representative signals on at least two respective channels,

(E3) combining the representative signals to provide a sum signal representative of the sum of the first and second signals,

- (E4) parallel acquisition of the representative signals and the sum signal,

(E5) calculating an interference function from the representative signals and the acquired sum signal, this calculation consisting in dividing the spectrum of the sum signal by the sum of the spectra of the representative signals,

(E6) determining the location of the partial discharge from the calculated interference function.

The locating method of claim 1 wherein the determining step comprises a sub-step of performing a wavelet transform.

A system for locating (100) a partial discharge in a high-voltage electrical apparatus (10, 1010) isolated by a dielectric fluid, said electrical apparatus comprising at least a first and a second UHF sensor (11, 12, 1011, 1012, 1013 ..., 101η),

the location system (100) being characterized in that it comprises:

at least a first and a second input connector (21, 22, 2021) intended to be respectively connected to the first and second UHF sensors (11, 12, 1011, 1012, 1013 ..., 101η) and adapted to recover respectively a first and a second signal respectively from the first and second UHF sensors (11, 12, 1011, 1012, 1013 ..., 101η),

at least a first and a second separation device respectively connected to the first and second input connectors (21, 22, 2021) and adapted to respectively share the first and second signals in at least two representative signals on at least two channels respectively,

at least one acquisition device (30, 1041, 1042, 1043, 104n) connected to the first and second separation devices and to the coupling device and adapted to acquire the representative signals and the sum signal in parallel,

The locating system of claim 3 including a coupling housing (20), said coupling housing (20) having the first and second input connectors (21,22), the first and second separating devices, and the coupling device, said coupling housing (20) having a first, a second and a third output connector (26, 27, 28) respectively connected to the first and second separating device and to the coupling device, said first, second and third output connectors being connected to the at least one acquisition device (30).

5. Location system according to claim 3 comprising at least a first and a second coupling housing (2020a),

the first coupling housing (2020a) having the first input connector (2021) and a third input connector (2022) connected to the second housing (2020a), a first and a third output connector (2026, 2027),

the second coupling housing (2020a) having at least the second input connector (2021), a second output connector (2026) and a fourth output connector (2025) through which the second coupling housing (2020a) is connected at the third input connector (2022) of the first coupling box,

the first and the second coupling housing (2020a) respectively having the first and second separating devices, the first and second separating devices being respectively connected to the first and second output connectors (2026),

the first coupling unit (2020a) further comprising the coupling device connected to the first separation device and the third input connector (2022), the latter being connected to the fourth output connector (2025) of the second coupling unit ( 2020a), the sum signal being provided through the third output connector (2027), the second separating device being connected to the fourth output connector (2025),

the first, second and third output connectors (2026, 2027) being connected to the at least one acquisition device.

6. Location system according to claim 5 wherein the first and the second coupling housing (2020a) are identical.

7. Location system according to any one of claims 3 to 6, comprising the electrical equipment (1010) high voltage isolated by a dielectric fluid,

wherein the first and second input connectors, the first and second separation devices and the coupling device are integrated in the electrical equipment (1010) with the first and second input connectors connected respectively to the first and second UHF sensors (1011, 1012, 1013, ... 101η),

the electrical apparatus (1010) having at least a first and a second output connector respectively connected to the first and second separation devices, and a third output connector connected to the coupling device.

8. Location system according to any one of claims 3 to 7,

wherein the acquisition device further comprises at least a first and a second acquisition module, the first and the second separation device being respectively connected to the first and second acquisition module and in which the coupling device is connected to the first acquisition module,

each of the first and second acquisition modules being connected, or intended to be connected, to the analysis unit.

9. Location system (100) according to any one of claims 3 to 8, wherein the acquisition device and the analysis unit are provided by at least one acquisition and analysis module independent of the high voltage electrical apparatus (1010) isolated by a dielectric fluid, said acquisition and analysis module having a first, a second and a third connector respectively connected to the first, second and third output connectors.

The locating system (100) according to any one of claims 3 to 9, wherein the first and second separating devices are each a divider (23, 24, 1021, 1022, 1023, ... 102n, 2023 , 2023b),

the coupling device being a mixer

(25, 1031, 1032, ... 103n, 2024) or an inverted mounted divider.

11. Coupling housing (20) for a system according to claim 4 taken alone or in combination with any one of claims 8 to 10, said coupling housing comprising:

a first and a second input connector (21, 22) for being respectively connected to a first and second UHF sensor (11, 12) of high voltage electrical equipment (10) insulated by a dielectric fluid, and adapted for respectively recovering a first and a second signal respectively from the first and the second UHF sensor (11, 12),

a first and a second separation device (23, 24) respectively connected to the first and second input connectors (21, 22) and adapted to separate respectively the first and the second signals in at least two representative signals on at least two respective paths,

at least one coupling device connected to the first and second separation devices and adapted to combine the representative signals so as to provide a sum signal representative of the sum of the first and second signals,

a first, a second and a third output connector (26, 27, 28) respectively connected to the first and second separation devices and to the coupling device, said first, second and third output connectors (26, 27, 28) being intended to be connected to at least one acquisition device (30) connected to an analysis unit to form a locating system (100) according to claim 4.

A coupling housing (2020a) for a locating system according to claim 5 or any one of claims 8 to 10 taken in combination with claim 5, comprising:

a first input socket (2021) for forming the first input connector of the location system, said first input socket (2021) being adapted to recover a first signal from a first UHF sensor,

a second input socket (2022) for forming the third input connector and for connection to a second identical coupling housing, said second coupling housing (2020a) having its first input socket (2021) connected to a second UHF sensor to form the second input connector of the location system,

a separation device connected to the first input socket (2021) and adapted to separate the first signal into three representative signals on three respective channels,

a coupling device connected to the separation device and to the second input terminal (2022) and adapted to combine the representative signal and a signal representative of the second signal provided by the second coupling unit (2020a) so as to provide a signal sum representative of the sum of the first signal and the second signal, a first and a second output socket (2025, 2026) each connected to the separation device,

a third output socket (2027) by which the sum signal is provided,

the second and the third output jacks (2026, 2027) being intended to respectively form the first and third output connectors and to be connected to at least one acquisition device (1041, 1042, ... 104n); - even connected to an analysis unit so as to form with the second coupling housing a locating system according to claim 5 or any one of claims 6 to 9 taken in combination with claim 5.