AU2013209382B2

AU2013209382B2 - Detection system for detecting impedance variation in a neutral conductor, transformer station compising such a system and method for detecting impedance variation in a neutral conductor with such a system

Info

Publication number: AU2013209382B2
Application number: AU2013209382A
Authority: AU
Inventors: Michel Clemence; Erick Contini
Original assignee: Schneider Electric Industries SAS
Current assignee: Schneider Electric Industries SAS
Priority date: 2012-07-31
Filing date: 2013-07-29
Publication date: 2017-01-12
Anticipated expiration: 2033-07-29
Also published as: CN103575995A; AU2013209382A1; EP2693227A2; FR2994275A1; ES2754810T3; EP2693227A3; EP2693227B1; FR2994275B1; CN103575995B

Abstract

is DETECTION SYSTEM FOR DETECTING IMPEDANCE VARIATION IN A NEUTRAL CONDUCTOR, TRANSFORMER STATION COMPRISING SUCH A SYSTEM AND METHOD FOR DETECTING IMPEDANCE VARIATION IN A NEUTRAL CONDUCTOR WITH SUCH A SYSTEM This detection system (20) is suitable for detecting impedance variation (84) in a neutral conductor (22) of a multiphase AC electrical network, the electrical network 10 comprising P phase conductors (34) and one neutral conductor (22), where P is an integer greater than 1. The detection system (20) comprises a group (42A) of P voltage sensors (56A, 58A, 60A), each voltage sensor (56A, 58A, 60A) being suitable for measuring the voltage of a phase respective conductor (34) in relation to the neutral conductor (22), 15 and a supervising device connected to each of the voltage sensors (56A, 58A, 60A) via a data link (62). The detection system (20) further comprises (N-1) other group(s) (42B, 42C, etc.) of P voltage sensors (56B, 58B, 60B, 56C, 58C, 60C), where N is an integer greater than 1, the N groups of voltage sensors (42A, 42B, 42C, etc.) being arranged at different 20 locations along the electrical network, and the supervising device is suitable for detecting, between two successive groups of sensors (42A, 42B), a variation in the voltage of a given phase conductor (34) in relation to the neutral conductor (22), in order to detect impedance variation (84) in the neutral conductor (22) and locate said impedance variation (84) between the two successive groups of sensors (42A, 42B). 25 Figure 1 Overvoltage detection on one of the phases by a voltage sensor 00 Alarm transmission from the voltage sensor to the supervisor i I Querying of the voltage sensors of the other two 120 phases by the supervisor Significant undervoltage detection by the voltage 130 sensors of the other pages Search for potential 140 faise alarm Determination of voltage sensors detecting the arnomaly or not 50 Location of fault 160 Fig3

Description

1 2013209382 29 Jul2013

DETECTION SYSTEM FOR DETECTING IMPEDANCE VARIATION IN A NEUTRAL CONDUCTOR. TRANSFORMER STATION COMPRISING SUCH A SYSTEM AND METHOD FOR DETECTING IMPEDANCE VARIATION IN A NEUTRAL CONDUCTOR WITH SUCH A SYSTEM

The present invention relates to a system for detecting impedance variation in a neutral conductor of a multiphase AC electrical network, the electrical network comprising P phase conductors and one neutral conductor, where P is an integer greater than 1. 5 This detection system comprises a group of P voltage sensors, each voltage sensor being suitable for measuring the voltage of a respective phase conductor in relation to the neutral conductor, and a supervising device connected to each of the voltage sensors via a data link.

The present invention also relates to an electrical transformer station to be 10 connected to a multiphase AC electrical network, the transformer station comprising P phase conductors, one neutral conductor and such a system for detecting impedance variation in a neutral conductor.

The present invention also relates to a method for detecting impedance variation in a neutral conductor of a multiphase AC electrical network with such a detection 15 system.

The document US 2007/0258175 A1 discloses a detection system of the type mentioned above. The detection system comprises means for measuring the voltage imbalance between the first conductor and the neutral conductor, on one hand, and between a second conductor and the neutral conductor, on the other. This system is 2 suitable for a two-phase electrical circuit. The detection system comprises means for comparing the voltage imbalance with respect to a predetermined threshold value. The system comprises means for generating an alarm if the voltage imbalance measured is greater than or less than any of the predetermined threshold values. In this way, the system, by measuring the voltages of both electrical phase conductors and comparing values to the predetermined thresholds, enables the generation of an alarm in relation to a neutral break in the instrumented electrical circuit, such as a consumer board.

However, such a detection system does not provide information on the status of the electrical network apart from the consumer board.

It would be desirable to propose a detection system suitable for detecting impedance variation in the neutral conductor on the electrical network and locating the neutral variation along the network.

Any discussion of documents, devices, acts or knowledge in this specification is included to explain the context of the invention. It should not be taken as an admission that any of the material formed part of the prior art base or the common general knowledge in the relevant art on or before the priority date of the claims herein.

Comprises/comprising and grammatical variations thereof when used in this specification are to be taken to specify the presence of stated features, integers, steps or components or groups thereof, but do not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

In accordance with a first aspect of the invention, there is provided a detection system for detecting impedance variation in a neutral conductor of a multiphase AC electrical network, the electrical network comprising P phase conductors and one neutral conductor, where P is an integer greater than 1, the system comprising: - a group of P voltage sensors, each voltage sensor being suitable for measuring the voltage of a phase respective conductor in relation to the neutral conductor, and - a supervising device connected to each of the voltage sensors via a data link, 3 wherein the system further comprises (N-1) other group(s) of P voltage sensors, where N is an integer greater than 1, the N groups of voltage sensors being arranged at different locations along the electrical network, and wherein the supervising device is suitable for detecting, between two successive groups of sensors, a variation in the voltage of a given phase conductor in relation to the neutral conductor, in order to detect impedance variation in the neutral conductor and locate said impedance variation between the two successive groups of sensors.

According to advantageous embodiments of the invention, the detection system may comprise one or a plurality of the following features, taken in isolation or according to any technical feasible combinations: - each voltage sensor comprises means for transmitting a warning message to the supervising device in the event of overvoltage or undervoltage detection for at least one phase conductor; - each voltage sensor comprises means for comparing the voltage measured with a predefined overvoltage threshold and undervoltage threshold, in order to detect an overvoltage or undervoltage; - the supervising device comprises means for comparing the voltage measured, received from a corresponding voltage sensor, with a predefined overvoltage threshold and undervoltage threshold, in order to detect an overvoltage or undervoltage; - the supervising device comprises means for communicating with each of the voltage sensors, suitable for transmitting a query to each of the voltage sensors in order to receive the voltage measured by each voltage sensor in response; - the supervising device comprises a calculating unit suitable for comparing the measured voltage of each phase conductor with a predefined overvoltage threshold and undervoltage threshold.

In accordance with another aspect of the invention, there is provided an electrical transformer station to be connected to a multiphase AC electrical network, the transformer station comprising - a first board comprising P electrical input conductors suitable for being connected to the electrical network, where P is an integer greater than 1, 4 - a second board comprising at least one output of P electrical conductors and one neutral conductor, - an electrical transformer connected between the first board and the second board and suitable for transforming an incoming current on the input conductors and having a first AC voltage into a current having a second AC voltage, and - a detection system for detecting impedance variation in the neutral conductor, wherein the detection system is according to the first aspect of the invention.

In accordance with another aspect of the invention, there is provided a method for detecting impedance variation in a neutral conductor of a multiphase AC electrical network, the electrical network comprising P phase conductors and the neutral conductor, where P is an integer greater than 1, the method comprising the following steps: - measurement, by a group of P voltage sensors at a given location of the electrical network, of the voltage of each phase conductor in relation to the neutral conductor, - transmission of the voltages measured to a supervising device, from the group of voltage sensors, wherein during the measurement step, the voltage of phase conductor in relation to the neutral conductor is measured at different locations along the electrical network, by N groups of P voltage sensors arranged at said various locations, and wherein the method further comprises the following step: - detection, between two successive groups of sensors, of a voltage variation in a given phase conductor in relation to the neutral conductor, in order to detect impedance variation in the neutral conductor and locate said impedance variation between the two successive groups of sensors, the detection step being performed by the supervising device on the basis of the measured voltages transmitted by each of the groups of voltage sensors. 4a

According to advantageous embodiments of the invention, the method for detecting impedance variation in the neutral conductor may comprise the following features: - after receiving a warning message from a voltage sensor of a given group, in the event of the detection of a voltage anomaly, such as overvoltage or undervoltage, for at least one phase conductor, the supervising device transmits queries to the various voltage sensors of the given group, in order to receive the voltages measured by the sensors of the given group; - after receiving the voltages measured by the sensors of the given group, the supervising device checks whether both an overvoltage for one phase conductor and an undervoltage for the other phase conductors are detected; - after receiving the voltages measured by the sensors of the given group, the supervising device checks that the voltage anomaly detected is not caused by the loss of any of the phases of the network or a load imbalance between the phases of the network; - after receiving a warning message from a voltage sensor of a given group, the supervising device further transmits queries to the various voltage sensors of the group(s) adjacent to the given group - the supervising device determines the group(s) of sensors detecting the voltage anomaly and that or those not detecting same and determines an impedance variation zone situated between the final group of sensors not indicating the anomaly and the first group of sensors indicating the anomaly.

These features and advantages of the invention will emerge on reading the description hereinafter, given merely at a non-limiting example, with reference to the appended figures, wherein: - figure 1 is a schematic representation of an electrical transformer station connected to a three-phase AC electrical network, the transformer station comprising a system for detecting variation according to the invention; - figure 2 is a larger-scale view of zone II in figure 1; - figure 3 is a flow chart of a method for detecting impedance variation on a neutral conductor in the electrical network. 2013209382 12 Dec 2016 4b

In figure 1, a transformer station 10 connected to an AC electrical network 12 comprises a first medium-voltage board 14, a second low-voltage board 16, an electrical 5 CONTINUES ON PAGE 5 5 2013209382 29 Μ 2013 transformer 18 connected between the first board and the second board and a system 20 for detecting impedance variation in a neutral conductor 22.

The transformer station 10 is suitable for transforming the electrical current output by the network 12 and having a first AC voltage, into an electrical current having a 5 second AC voltage.

The electrical network 12 is a multiphase AC network comprising P phases, where P is an integer greater than 1, such as a three-phase network. In other words, in the embodiment described, P is equal to 3.

The electrical network 12 is a medium-voltage network, i.e. a network wherein the 10 voltage is greater than 1000 Volts and less than 50,000 Volts. The first three-phase voltage is thus a medium voltage.

The first board 14 comprises a plurality of inputs 24, each input 24 comprising P electrical input conductors 26, where P is an integer greater than 1, and an isolating switch 28. 15 The first board 14 comprises an input circuit breaker 30 connected between the transformer 18 and the inputs 24.

The second board 16 comprises a plurality of outputs 32, each output 32 being suitable for supplying the second AC voltage and comprising P electrical output conductors 34 and the neutral conductor 22. 20 The second board 16 comprises an output circuit breaker 36 connected between the transformer 18 and the outputs 32.

The electrical transformer 18 is suitable for transforming the current from the electrical network having the first AC voltage into the current supplied to the second board 16 and having the second AC voltage. The electrical transformer 18 comprises a 25 primary winding 38 connected to the first board 14 and a second winding 40 connected to the second board 16.

The detection system 20 is suitable for detecting impedance variation in the neutral conductor 22 along said conductor.

The detection system 20 comprises N groups 42A, 42B, ..., 42N of voltage 30 sensors wherein three successive groups 42A, 42B, 42C are represented in figure 1, and wherein one group 42A can be seen on a larger scale in figure 2. Each of these N groups comprises P sensors, for example 56A, 58A, 60A for the group 42A, for measuring each of the voltages of the P phase conductors in relation to the neutral 6 conductor 22. In the embodiment described in figure 1, each group 42A, 42B, 42C consists of P voltage sensors 56A, 58A, 60A, 56B, 58B, 60B, 56C, 58C, 60C,

In this way, N voltage sensors are distributed along each output conductor 34 and are suitable for measuring the voltage of each phase conductor 34 in relation to the neutral conductor 22 at N different points. This is the case for example of the voltage sensors 56A, 56B, 56C for the voltage measurements of the first phase.

The detection system 20 comprises a supervising device 61 connected to each of the voltage sensors 56A, ..., 60C via a data link 62.

Each output 32 is a low-voltage output, i.e. an output wherein the voltage is less than 1000 Volts. The second three-phase voltage is thus a low voltage.

Each of the phase conductors 34 carries electricity to loads 63 of consumers situated along the electrical network. Some of these loads, particularly those comprising electronic circuits, are susceptible to electrical network voltage variations.

Each of the voltage sensors 56A, ..., 60N comprises a processor 64 and a memory 65 associated with the processor 64. The memory 65 is suitable for storing a first communication software 66 and a first calculation software 68.

In one embodiment, each sensor 56A, ..., 60N comprises a radioelectric transceiver 70 suitable for communicating in both directions with the supervising device 61, each data link 62 being a radioelectric data link in this case.

Alternatively, each sensor 56A, ..., 60N comprises a PLC injector, not shown, suitable for suitable for communicating in both directions with the supervising device 61, each data link 62 being a data transfer link via power line communication.

The supervising device 61 of the detection system 20 is suitable for communicating with the voltage sensors 56A,..., 60N and with a control centre 72.

The supervising device 61 comprises a processor 74 and a memory 76 associated with the processor 74. The memory 76 is suitable for storing a second communication software 78 and a second calculation software 80.

In the embodiment, the supervising device 61 comprises a radioelectric transceiver 82 suitable for communicating with each of the sensors and with the control centre 72. In this embodiment, the control centre 72 also comprises a transceiver, not shown, suitable for communicating with the supervising device 61. Alternatively, the communications described above use a data transfer link via power line communication.

The first communication software 66 is suitable for establishing communication between each voltage sensor 56A..... 60N and the supervising device 61. The first 7 2013209382 29 Jul 2013 communication software 66 is particularly suitable for transmitting a warning message to the supervising device 61 in the event of detection of overvoltage or undervoltage by the first calculation software 68 and for at least one phase conductor 34,

The first calculation software 68 is suitable for detecting an overvoltage or 5 undervoltage measured by a given voltage sensor 56A, ..., 60N, based on a predefined overvoltage and undervoltage threshold. The first calculation software 68 is particularly suitable for comparing the voltage measured with a predefined overvoltage threshold and undervoltage threshold, in order to detect said overvoltage or undervoltage.

Alternatively, the voltage sensors 56A, ..., 60N communicate the voltages 10 measured directly to the supervising device 61 which, using the second calculation software 80, is suitable for determining the voltage sensors 56A, ..., 60N measuring an overvoltage or an undervoltage in relation to predefined thresholds.

These two softwares 66 and 68 are suitable for communicating together. In this way, the detection of a voltage anomaly detected by the first calculation software 68 15 gives rise to the transmission of a warning by the first communication software 66 to the supervising device 61.

The second communication software 78 is suitable for establishing communication between the supervising device 61 and the various voltage sensors of the network 56A, ..., 60N, and between the supervising device 61 and the control centre 20 72. The second communication software 78 is suitable for transmitting queries to each of the voltage sensors 56A, .... 60N in order to receive the voltage measured by each of these sensors in response.

The second calculation software 80 is suitable, on the basis of the data communicated by the voltage sensors 56A, ..., 60N, for determining an undervoltage or 25 overvoltage anomaly with a predefined overvoltage threshold or undervoltage threshold.

Alternatively, when the voltage sensors 56A, ..., 60N communicate the voltages measured directly to the supervising device 61, the second calculation software 80 compares the voltages measured, received from the voltage sensors 56A, ..., 60N, with a predefined overvoltage threshold and undervoltage threshold, in order to detect an 30 overvoltage or undervoltage.

An impedance variation 84 on the neutral conductor 22 is represented in figure 1. The impedance variation 84 consists, for example, of a neutral conductor break, or neutral conductor contact degradation. 8

The operation of the detection system will now be described in view of figure 3. Figure 3 represents a flow chart of the steps of a detection method implemented by the detection system 20 comprising the N groups 42A, .... 42N of voltage sensors distributed along the output conductors 34, and by the supervising device 61.

In figure 3, during the first step 100, a voltage sensor, for example the sensor 56B, detects the presence of an overvoltage on one of the phase conductors 34. The detection of the overvoltage corresponds, for example, to a voltage measured between the phase conductor 34 and the neutral conductor 22 10% greater than the rated voltage of said phase conductor 34 in relation to the neutral conductor 22, i.e. 110% of the rate voltage, i.e. approximately 260V in the example of an embodiment in figure 1.

After detecting an overvoltage on any of the phase conductors 34, the voltage sensor detecting the anomaly transmits, during the step 110, an alarm to the supervising device 61.

On receiving the alarm, supervising device 61 queries the two voltage sensors 58B, 60B belonging to the same group 42B as the sensor 56B detecting the anomaly.

During the step 130, the supervising device 32 checks that the overvoltage detected on any of the voltage sensors, such as the sensor 56B in the example in figure 1, occurs in parallel with an undervoltage measured on the two other voltage sensors of the group 42B, such as the sensors 58B and 60B. In the case of a three-phase network and for a predetermined overvoltage threshold, equal to 110% of the rated voltage, the supervising device 61 checks than an undervoltage of at least 5% is observed by any one of the voltage sensors 58B, 60B associated with the two other phase conductors. In other words, the supervising device 61 checks that at least one voltage sensor 58B, 60B from the same group 42B as the sensor 46B detecting the overvoltage measures a voltage less than 95% of the corresponding rated voltage, i.e. 228V in the example of an embodiment in figure 1.

Following the step 130, the step 140 consists of checking that the above detections are indeed representative of impedance variations, such as a neutral break. In other words, the step 140 consists of locating a potential false alarm. In particular, the supervising device 61 checks that the voltage anomaly detection is not due to the loss of any of the phases of the medium-voltage power supply network, whereby the overvoltage phenomenon in any of the phase conductors 34 occurs on the second low-voltage board 16, and the two other phase conductors have undervoltages in the region of 50%. 9 2013209382 29 Μ 2013

In some cases, the presence of decentralised in-line power production, via photovoltaic panels for example gives rise to an overvoltage in the region of 10% on one of the phases in the network. Conversely, in some cases, the presence of a significant load on any of the phases of the network gives rise to an undervoltage in the region of 5 5% to 10% on the other phases of the network. In one embodiment, the supervising device 61 measures the currents circulating on each of the phases, and all the powers produced or consumed on the same phases. It thus distinguishes between voltage anomalies due to decentralised production and to the presence of one or a plurality of significant load(s) on the network from those due to neutral conductor degradation. 10 Moreover, neutral conductor degradation is characterised in that it gives rise to a sudden variation in network phase voltages.

Following the detection of a voltage anomaly representing impedance variation of the neutral 84 during the step 140, the step 150 is intended to determine the final sensor 56A not indicating the impedance variation and the first sensor 56B indicating the 15 impedance variation.

For this purpose, after measuring a voltage anomaly on any of the phase conductors 34, and after the warning to the supervising device 61 by the voltage sensor 56B, the supervising device 61 queries the groups of sensors 42A, 42C adjacent to the sensors 56B, 58B, 60B. If any of these groups of sensors does not measure the 20 anomaly, such as the group 42A, the supervising device 61 infers that the location of the impedance variation is situated between the group 42B that measured the anomaly and the group 42A queried that did not measure the anomaly.

If the queried groups also measure the anomaly, the supervising device 61 further queries the adjacent groups upstream and downstream from the previously 25 queried groups. In this way, recursive querying of the groups of sensors situated upstream and downstream from the first group 42B measuring the anomaly is suitable, after a number of queries, for locating the first group 42A of sensors not measuring the voltage anomaly.

Finally, during the step 160, the impedance variation zone is located by the zone 30 situated between the final sensor not indicating a voltage anomaly 56A and the first sensor indicating a voltage anomaly 56B,

Once the location has been carried out by the supervising device 61, the anomaly location information is sent to the control centre 72 to enable maintenance to be scheduled on the network. 10

The detection system according to the invention is thus suitable not only for detecting impedance variation, such a neutral break, but also for locating the zone of the impedance variation along the low-voitage network due to the arrangement of the N groups 42A, .,,, 42N of voltage sensors along the low-voltage network.

Moreover, the communication between each voltage sensor 56A.....60N and the supervising device 61 is suitable for distinguishing voltage anomalies associated with the structure of the medium-voltage network 12 from voltage anomalies due to impedance variation 84 requiring maintenance.

The system and the method according to the invention are thus suitable for detecting degradation of a neutral conductor prior to the break thereof, enabling preventive maintenance on the network.

An intervention on the low-voltage network is then carried out before an outright break of the neutral 22 occurs and damages or destroys the loads 63 connected to the low-voltage network. This helps prevent degradation of these loads.

The use of such a device and such a method also enables the use of voltage sensors 56A.....60N comprising radioelectric transceivers 70, thus avoiding the need for staff to travel for readings.

Such a device and such a method are also suitable, following the location of the fault 84 on the electrical network, for transmitting an alarm from the supervising device 61 to the control centre 72 with the location information associated with said fault 84. The control centre 72 then sends a maintenance team to check the status of the connections of the neutral conductor 22 in a targeted and previously located zone.

The maintenance teams thus optimise the availability of their resources for maintenance of the impedance variation zone. This optimisation is enabled since the maintenance operators can travel directly to the impedance variation zone, without wasting time locating the zone.

It is thus envisaged that the detection system according to the invention is suitable not only for detecting but also for locating an impedance variation on the network, such as a neutral break, via voltage monitoring along the electrical network.

Claims

CLAIMS:

1. Detection system for detecting impedance variation in a neutral conductor of a multiphase AC electrical network, the electrical network comprising P phase conductors and one neutral conductor, where P is an integer greater than 1, the system comprising: - a group of P voltage sensors, each voltage sensor being suitable for measuring the voltage of a phase respective conductor in relation to the neutral conductor, and - a supervising device connected to each of the voltage sensors via a data link, wherein the system further comprises (N-1) other group(s) of P voltage sensors, where N is an integer greater than 1, the N groups of voltage sensors being arranged at different locations along the electrical network, and wherein the supervising device is suitable for detecting, between two successive groups of sensors, a variation in the voltage of a given phase conductor in relation to the neutral conductor, in order to detect impedance variation in the neutral conductor and locate said impedance variation between the two successive groups of sensors.
2. Detection system according to claim 1, wherein each voltage sensor comprises means for transmitting a warning message to the supervising device in the event of overvoltage or undervoltage detection for at least one phase conductor.
3. Detection system according to either claim 1 or 2, wherein each voltage sensor comprises means for comparing the voltage measured with a predefined overvoltage threshold and undervoltage threshold, in order to detect an overvoltage or undervoltage.
4. Detection system according to either claim 1 or 2, wherein the supervising device comprises means for comparing the voltage measured, received from a corresponding voltage sensor, with a predefined overvoltage threshold and undervoltage threshold, in order to detect an overvoltage or undervoltage.
5. Detection system according to any one of the preceding claims, wherein the supervising device comprises means for communicating with each of the voltage sensors, suitable for transmitting a query to each of the voltage sensors in order to receive the voltage measured by each voltage sensor in response.
6. Detection system according to any one of the preceding claims, wherein the supervising device comprises a calculating unit suitable for comparing the measured voltage of each phase conductor with a predefined overvoltage threshold and undervoltage threshold.
7. Electrical transformer station to be connected to a multiphase AC electrical network, the transformer station comprising - a first board comprising P electrical input conductors suitable for being connected to the electrical network, where P is an integer greater than 1, - a second board comprising at least one output of P electrical conductors and one neutral conductor, - an electrical transformer connected between the first board and the second board and suitable for transforming an incoming current on the input conductors and having a first AC voltage into a current having a second AC voltage, and - a detection system for detecting impedance variation in the neutral conductor, wherein the detection system is according to any one of the preceding claims.
8. Method for detecting impedance variation in a neutral conductor of a multiphase AC electrical network, the electrical network comprising P phase conductors and the neutral conductor, where P is an integer greater than 1, the method comprising the following steps: - measurement, by a group of P voltage sensors at a given location of the electrical network, of the voltage of each phase conductor in relation to the neutral conductor, - transmission of the voltages measured to a supervising device, from the group of voltage sensors, wherein during the measurement step, the voltage of phase conductor in relation to the neutral conductor is measured at different locations along the electrical network, by N groups of P voltage sensors arranged at said various locations, and wherein the method further comprises the following step: - detection, between two successive groups of sensors, of a voltage variation in a given phase conductor in relation to the neutral conductor, in order to detect impedance variation in the neutral conductor and locate said impedance variation between the two successive groups of sensors, the detection step being performed by the supervising device on the basis of the measured voltages transmitted by each of the groups of voltage sensors.
9. Method according to claim 8, wherein, after receiving a warning message from a voltage sensor of a given group, in the event of the detection of a voltage anomaly, such as overvoltage or undervoltage, for at least one phase conductor, the supervising device sends queries to the various voltage sensors of the given group, in order to receive the voltages measured by the sensors of the given group.
10. Method according to claim 9, wherein, after receiving the voltages measured by the sensors of the given group, the supervising device checks whether both an overvoltage for one phase conductor and an undervoltage for the other phase conductors are detected.
11. Method according to either claim 9 or 10, wherein, after receiving the voltages measured by the sensors of the given group, the supervising device checks that the voltage anomaly detected is not caused by the loss of any of the phases of the network or by a load imbalance between the phases of the network.
12. Method according to any one of claims 9 to 11, wherein, after receiving a warning message from a voltage sensor of a given group, the supervising device further transmits queries to the various voltage sensors of the group(s) adjacent to the given group.
13. Method according to claim 12, wherein the supervising device determines the group(s) of sensors detecting the voltage anomaly and that or those not detecting same and determines an impedance variation zone situated between the final group of sensors not indicating the anomaly and the first group of sensors indicating the anomaly.