AU2016200357A1

AU2016200357A1 - Device and method for monitoring a voltage or a current, system for monitoring an electrical panelboard, electrical cabinet and transformer substation associated therewith

Info

Publication number: AU2016200357A1
Application number: AU2016200357A
Authority: AU
Inventors: Olivier Coutelou; Maxime Gaillard; Christophe Mollier; Damien Sillans
Original assignee: Schneider Electric Industries SAS
Current assignee: Schneider Electric Industries SAS
Priority date: 2015-01-22
Filing date: 2016-01-21
Publication date: 2016-08-11
Anticipated expiration: 2036-01-21
Also published as: AU2016200357B2; FR3032037B1; JP6625440B2; EP3048448A1; FR3032037A1; JP2016148654A; EP3048448B1

Abstract

Device and method for monitoring a voltage or a current, system for monitoring an electrical panelboard, electrical cabinet and transformer substation associated therewith Electronic device (60; 62A, ..., 62N) for monitoring an electrical quantity, the device comprising: - a module (66; 76A, ... , 76N) for measuring at least one value of the electrical quantity, - a module (103; 11 9A,...,1 19N) for sampling the measured value, - an emission module (106; 128A, ... , 128N) configured to emit, with an emission period, a message. The device furthermore comprises a module (104; 123A,...,123N) for determining a first table and a second table, the first table containing a plurality of first coefficients, each first coefficient being a function of a cosine and depending on the frequency of the voltage, and the second table containing a plurality of second coefficients, each second coefficient being a function of a sine and depending on the said frequency, the number of coefficients of each table being equal to the number of samples of the quantity during the emission period. Initialization Transmission of a frequency value j Adaptation of the 208 sampling frequency J Measurement of the 210 voltage Compression of the measured voltage, and fomrulation of 220 the first message M1 Emission of the first message M1

Description

Device and method for monitoring a voltage or a current, system for monitoring an electrical panelboard, electrical cabinet and transformer substation associated therewith

The present invention relates to an electronic device for monitoring an electrical quantity from among a voltage and an intensity relating to an AC current flowing in an electrical conductor, the AC current comprising at least one phase.

The monitoring device comprises a measurement module configured to measure at least one value of the electrical quantity, a radioelectric emitter-receiver, and an emission module linked to the radioelectric emitter-receiver.

The present invention also relates to an electronic system for monitoring an electrical panelboard comprising at least one primary electrical outlet conductor and at least one secondary electrical outlet conductor, each secondary outlet conductor being connected electrically to a corresponding primary outlet conductor.

The monitoring system comprises such monitoring devices, namely a first electronic device for monitoring the voltage of each primary electrical outlet conductor, and at least one second electronic device for monitoring the intensity of the AC current flowing in each secondary electrical conductor.

The present invention also relates to an electrical cabinet comprising an electrical panelboard comprising electrical outlet conductors, and such a monitoring system.

The present invention also relates to a substation for transforming an electric current exhibiting a first AC voltage into an electric current exhibiting a second AC voltage, this transformation substation comprising such an electrical cabinet, an inlet panelboard comprising at least one electrical inlet conductor suitable for being linked to an electrical network, the inlet conductor exhibiting the first AC voltage, the panelboard of the cabinet forming an outlet panelboard whose corresponding outlet conductors exhibit the second AC voltage. The transformation substation furthermore comprises an electrical transformer connected between the inlet panelboard and the outlet panelboard, the transformer being suitable for transforming the current exhibiting the first AC voltage into the current exhibiting the second AC voltage.

The present invention also relates to a method for monitoring an electrical quantity from among a voltage and an intensity relating to an AC current flowing in an electrical conductor. A monitoring system of the aforementioned type is known from document WO 2013/017663 A1. This monitoring system makes it possible in particular to measure the electrical energy of the current flowing in secondary conductors linked to a primary conductor, the secondary conductors corresponding to outlet conductors of an outlet panelboard and exhibiting substantially the same voltage as the primary conductor. The primary module forms a device for monitoring the voltage of the primary conductor, and each secondary module forms a device for monitoring the intensity of the current flowing in the corresponding secondary conductor.

The primary module measures the voltage of the primary conductor, and transmits with an emission period a first message containing a synchronization datum and values representative of the voltage. Accordingly, the primary module calculates two correlation tables each covering a voltage period. The primary module thereafter samples the voltage during a voltage period, and then calculates, on the basis of the correlation tables, the Fourier series decomposition of the voltage measured over this voltage period. The Fourier coefficients calculated are thereafter included in the first message. Each secondary module then synchronizes itself with the aid of the synchronization datum received; measures, in a manner synchronized with the primary module, the Fourier coefficients of the intensity of the current flowing in the corresponding secondary conductor; and then calculates the energy of the current flowing in the said secondary conductor with the aid of the measured intensity values and of the voltage values contained in the first message. Each secondary module dispatches thereafter, destined for a centralization module and according to a token-based mechanism distributed between the secondary modules, a second message containing the identifier of the corresponding secondary module and the energy calculated by the secondary module, for example in the form of various values of energy meters.

Flowever, this monitoring system is not suitable for networks in which the voltage and/or the frequency vary in a noticeable manner, such as insular electrical networks. Indeed, the measurement of the voltage is done, for each emission period, over a single voltage period that is considered to be representative, the emission period corresponding to several voltage periods. The emission period is, for example, equal to 1 second, whereas the voltage period is generally equal to 16.66 milliseconds (ms) in the United States and to 20 ms in Europe. The measurement of the voltage is therefore performed over a brief part of the emission period.

The aim of the invention is to propose devices for monitoring the voltage, and respectively the intensity, of an AC current flowing in an electrical conductor, and a monitoring system comprising such devices, making it possible to remedy the aforementioned problem.

For this purpose, the subject of the invention is an electronic monitoring device of the aforementioned type, furthermore comprising a module for determining a first table and a second table, and a module for calculating at least one parameter for monitoring the quantity on the basis of the first table, of the second table, and of samples of the quantity, arising from the sampling module, the first table containing a plurality of first coefficients, each first coefficient being a function of a cosine and depending on the frequency of the voltage of the electrical conductor, and the second table containing a plurality of second coefficients, each second coefficient being a function of a sine and depending on the said frequency, the number of coefficients of each table being equal to the number of samples of the quantity during the emission period.

With the monitoring device according to the invention, the electrical energy is calculated in a more accurate and faster manner. In particular, the first and second tables are calculated for the whole of the emission period, and the calculation of the electrical energy therefore takes into account the variations of the voltage and/or of the intensity over the whole of the emission period. Furthermore, the use of the first and second tables makes it possible to reduce the electrical energy calculation time.

With the monitoring system of the prior art, the voltage is measured over a single voltage period, and is considered not to vary over the remainder of the emission period.

According to other advantageous aspects of the invention, the electronic monitoring device comprises one or more of the following characteristics, taken in isolation or in accordance with all the technically possible combinations: - the first coefficients satisfy the equation: C‘ m =cos(2xIIxFx jxmxPsmp), and the second coefficients satisfy the equation: C^,m = sin(2 xIIxFxyxmx Psmp) where j lies between 1 and J, J being an integer, preferably greater than or equal to 5, PSmp is the sampling period for the quantity, and m is a sample index varying between 1 and Ntotal_smp, Ntotal_smp being an integer representing the number of samples of the quantity during the emission period; - the determination module is suitable for recalculating, during each emission period, the first table and the second table on the basis of a value of the frequency measured during the penultimate emission period; - the sampling module is able to sample the electrical quantity with a sampling period and the value of the sampling period is dependent on a value of the frequency of the voltage measured during the penultimate emission period; - the device is adapted for monitoring the voltage of the electrical conductor, the measurement module is configured to measure the frequency of the voltage, and the message emitted furthermore contains a measured value of the frequency of the voltage; - the measurement module is configured to calculate, for each voltage sample, the real part and imaginary part of a corresponding voltage phasor satisfying the equations:

where Nsmp is the number of voltage samples acquired during a voltage period, the voltage period being equal to the inverse of the frequency, and to measure, with a measurement period, a value of the frequency on the basis of two voltage phasors corresponding respectively to two temporal instants separated temporally by a measurement period; - the measurement period is substantially equal to half the voltage period; - the device is adapted for monitoring an intensity, and comprises a module for receiving a data message comprising a measured value of the frequency of the voltage.

The subject of the invention is also an electronic system for monitoring an electrical panelboard comprising at least one primary electrical outlet conductor and at least one secondary electrical outlet conductor, the or each secondary outlet conductor being connected electrically to a corresponding primary outlet conductor, the corresponding outlet conductors exhibiting an AC voltage, the system comprising: - a first electronic device for monitoring the voltage of each primary electrical outlet conductor, - at least one second electronic device for monitoring the intensity of the AC current flowing in each secondary electrical conductor, in which each electronic monitoring device is such as defined hereinabove.

According to other advantageous aspects of the invention, the electronic monitoring system comprises one or more of the following characteristics, taken in isolation or in accordance with all the technically possible combinations: - each electronic monitoring device furthermore comprises a module for determining a first table and a second table, and a module for calculating at least one parameter for monitoring the quantity on the basis of the first table, of the second table, and of samples of the quantity, arising from the sampling module, the first table containing a plurality of first coefficients, each first coefficient being a function of a cosine and depending on the frequency of the voltage of the electrical conductor, and the second table containing a plurality of second coefficients, each second coefficient being a function of a sine and depending on the said frequency, the number of coefficients of each table being equal to the number of samples of the quantity during the emission period; - the first monitoring device is adapted for monitoring the voltage of the electrical conductor, the measurement module is configured to measure the frequency of the voltage, and the message emitted furthermore contains a measured value of the frequency of the voltage, and each second monitoring device is adapted for monitoring an intensity, and comprises a module for receiving a data message comprising a measured value of the frequency of the voltage; - the first monitoring device furthermore comprises a module for determining a first table and a second table, and a module for calculating at least one parameter for monitoring the quantity on the basis of the first table, of the second table, and of samples of the quantity, arising from the sampling module, the first table containing a plurality of first coefficients, each first coefficient being a function of a cosine and depending on the frequency of the voltage of the electrical conductor, and the second table containing a plurality of second coefficients, each second coefficient being a function of a sine and depending on the said frequency, the number of coefficients of each table being equal to the number of samples of the quantity during the emission period, and each second monitoring device comprises a determination module able to calculate a third correlation table and a fourth correlation table, the third table containing a plurality of the first coefficients, and the fourth table containing a plurality of the second coefficients, the number of coefficients of each table being equal to the number of samples of the quantity during a corresponding voltage period.

The subject of the invention is also an electrical cabinet comprising: - a panelboard comprising at least one primary electrical outlet conductor and at least one secondary electrical outlet conductor, the or each secondary outlet conductor being connected electrically to a corresponding primary outlet conductor, the current flowing in the corresponding outlet conductors exhibiting an AC voltage, and - a system for monitoring the electrical panelboard, in which the monitoring system is such as defined hereinabove.

The subject of the invention is also a substation for transforming an electric current exhibiting a first AC voltage into an electric current exhibiting a second AC voltage, comprising an electrical cabinet such as defined hereinabove, an inlet panelboard comprising at least one electrical inlet conductor suitable for being linked to an electrical network, the inlet conductor exhibiting the first AC voltage, the panelboard of the cabinet forming an outlet panelboard whose corresponding outlet conductors exhibit the second AC voltage, and an electrical transformer connected between the inlet panelboard and the outlet panelboard, the transformer being suitable for transforming the current exhibiting the first AC voltage into the current exhibiting the second AC voltage.

The subject of the invention is also a method for monitoring an electrical quantity from among a voltage and an intensity relating to an AC current flowing in an electrical conductor, the AC current comprising at least one phase, the method being implemented by an electronic monitoring device, and comprising the following steps: - b) the measurement of at least one value of the electrical quantity and the sampling of the measured value, - d) the emission, with an emission period, of a data message containing a set of at least one parameter for monitoring the measured quantity, destined for another electronic device, the method comprising, furthermore, prior to step b), the following step: - a) the determination of a first table and of a second table, the first table containing a plurality of first coefficients, each first coefficient being a function of a cosine and depending on the said frequency of the voltage of the electrical conductor, and the second table containing a plurality of second coefficients, each second coefficient being a function of a sine and depending on the said frequency, and the number of coefficients of each table being equal to the number of samples of the quantity during the emission period, and in that it comprises, furthermore, after step b) and prior to step d), the following step: - c) the calculation of at least one parameter for monitoring the quantity on the basis of the first table, of the second table, and of samples of the quantity, obtained during step b).

These characteristics and advantages of the invention will become apparent on reading the description which follows, given solely by way of nonlimiting example and with reference to the appended drawings in which: - Figure 1 is a schematic representation of a transformation substation comprising a first panelboard, a second panelboard connected to the first panelboard by way of a transformer and a system for monitoring the electrical energy of the current flowing in outlet conductors of the second panelboard, - Figure 2 is a schematic representation of the monitoring system of Figure 1, the monitoring system comprising a first device for measuring the voltage, a plurality of second devices for measuring the intensity and a centralization device, - Figure 3 is a schematic representation of the second device of Figure 2, - Figure 4 is a flowchart of the steps, implemented by the first device of Figure 2, of a monitoring method according to the invention, - Figure 5 is a flowchart of the steps, implemented by the second devices of Figures 2 and 3, of the same monitoring method, - Figure 6 is a flowchart of the steps, implemented by the centralization device of Figure 2, of the same monitoring method, - Figure 7 is a timechart representing the instants of emission and of reception of a first message, the latter being emitted by the first device destined for the second devices, - Figure 8 is a timechart representing the temporal periods for which coefficients of a Fourier series decomposition of the voltage, and respectively of the intensity, are determined and also the temporal instants of preparation of the first message, of emission of the first message and of calculation of the electrical energy, corresponding to a first embodiment, and - Figure 9 is a timechart representing the temporal periods for which coefficients of a Fourier series decomposition of the voltage, and respectively of the intensity, are determined and also the temporal instants of preparation of the first message, of emission of the first message and of calculation of the electrical energy, corresponding to another embodiment.

In the subsequent description, the expression "substantially equal to" defines a relation of equality to plus or minus 10 %, preferably to plus or minus 5 %.

In Figure 1, a transformation substation 10 connected to an electrical network 12 comprises a first panelboard 14, also called the inlet panelboard, a second panelboard 16, also called the outlet panelboard, an electrical transformer 18 connected between the first panelboard and the second panelboard and a system 20 for monitoring the second panelboard.

As a variant, an electrical cabinet, not represented, comprises the second panelboard 16 and the monitoring system 20. Stated otherwise, the electrical cabinet comprises the elements of the transformation substation 10 with the exception of the electrical transformer 18 and of the first panelboard 14, the second panelboard 16 being for example supplied directly at low voltage.

The transformation substation 10 is suitable for transforming the electric current delivered by the network 12 and exhibiting a first AC voltage, into an electric current exhibiting a second AC voltage.

The electrical network 12 is an AC network, such as a three-phase network. The electrical network 12 is, for example, a medium-voltage network, that is to say of voltage greater than 1 000 V and less than 50 000 V. The first three-phase voltage is then a medium voltage. As a variant, the electrical network 12 is a high-voltage network, that is to say of voltage greater than 50 000 V.

The first panelboard 14 comprises several inlets 22, each inlet 22 comprising a first 24A, 24B, a second 26A, 26B, and a third 28A, 28B inlet conductors. Each first, second, third inlet conductor 24A, 24B, 26A, 26B, 28A, 28B is linked to the electrical network by way of a respective inlet isolator 32. The three-phase current flowing in the corresponding inlet conductors 24A, 24B, 26A, 26B, 28A, 28B exhibits the first three-phase voltage.

The second panelboard 16 comprises a first 34, a second 36, a third 38 and a fourth 39 primary conductors and a plurality N of outlets 40A, 40B, ...40N, namely a first outlet 40A, a second outlet 40B, ..., an Nth outlet 40N, each outlet 40A, 40B, ..., 40N being suitable for delivering a three-phase voltage.

Each outlet 40A, 40B, 40N is a low-voltage outlet, that is to say of voltage less than 1 000 V. The second three-phase voltage is then a low voltage. As a variant, each outlet 40A, 40B, ..., 40N is a medium-voltage outlet, that is to say of voltage greater than 1 000 V and less than 50 000 V.

The first outlet 40A comprises a first 42A, a second 44A, a third 46A and a fourth 48A secondary conductors and three outlet isolators 50. The first, second and third secondary conductors 42A, 42B, 42C are respectively linked to the first, second and third primary conductors 34, 36, 38 by way of a corresponding outlet isolator 50. The fourth secondary conductor 48A is directly connected to the fourth primary conductor 39.

The primary outlet conductors 34, 36, 38 and the corresponding secondary outlet conductors 42A, 44A, 46A exhibit substantially the same voltage, namely respectively a first voltage U1, a second voltage U2 and a third voltage U3 corresponding to the three phases of the second three-phase voltage.

The other outlets 40B, ...40N are identical to the first outlet 40A described previously, and comprise the same elements, each time replacing the letter A by the corresponding letter B, ..., N relating to the references of the elements.

The electrical transformer 18 is suitable for transforming the current arising from the electrical network exhibiting the first AC voltage into the current delivered to the second panelboard 16 and exhibiting the second AC voltage. The electrical transformer 18 comprises a primary winding 52 connected to the first panelboard 14 and a secondary winding 54 connected to the second panelboard 16.

The monitoring system 20 is configured to monitor the second panelboard 16, in particular to calculate the electrical energy of the current flowing in the or each secondary outlet conductor 42A, 44A, 46A, 42B, 44B, 46B, ..., 42N, 44N, 46N.

The monitoring system 20, visible in Figure 2, comprises a first electronic device 60 for monitoring the voltage U1, U2, U3 of each primary electrical outlet conductor 34, 36, 38, a plurality N of second electronic devices 62A, 62B, ..., 62N for monitoring the intensity 11 A, ..., I3N of the AC current flowing in each secondary electrical conductor 42A, ..., 46N, and an electronic centralization device 64.

The first device 60 comprises a module 66 for measuring the voltage of the current flowing in the corresponding primary conductor 34, 36, 38, and an information processing unit 68. The first device 60 also comprises a radioelectric emitter-receiver 70, a radioelectric antenna 72, and an electrical power supply module 74 for the measurement module, for the information processing unit and for the radioelectric emitter-receiver.

The second device with the reference 62A comprises, for each of the first 42A, second 44A and third 46A secondary conductors, a sensor 76A of the intensity of the current flowing in the corresponding secondary conductor 42A, 44A, 46A. The second device 62A comprises an information processing unit 78A, a radioelectric emitter-receiver 80A, and a radioelectric antenna 82A. The second device 62A also comprises an electrical power supply module 84A for the information processing unit and for the radioelectric emitter-receiver. The second device 62A is identified by a unique number, also called an identifier.

The other second devices 62B, ..., 62N are identical to the second device 62A described previously, and comprise the same elements, each time replacing the letter A by the corresponding letter B, ..., N relating to the references of the elements. Each of the other second devices 62B, ..., 62N also exhibits a unique identifier.

The centralization device 64 comprises an information processing unit 86, a database 88 and a man-machine interface 90. The centralization device 64 comprises a radioelectric emitter-receiver 92, a radioelectric antenna 94 and an electrical power supply module 96 for the information processing unit, for the database, for the man-machine interface and for the radioelectric emitter-receiver.

The measurement module 66 is suitable for measuring the first voltage U1 of the phase flowing through the first primary conductor 34, the second voltage U2 of the phase flowing through the second primary conductor 36, and the third voltage U3 of the phase flowing through the third primary conductor 38. The measurement module 66 is also suitable for measuring the frequency F of the three-phase voltage flowing through the primary conductors 34, 36, 38.

The information processing unit 68 comprises a processor 98 and a memory 100 able to store a first piece of software 102 for acquiring values of the voltages U1, U2, U3 measured by the measurement module 66 and a first piece of software 103 for sampling, with a sampling period Psmp, the value of the measured voltage U1, U2, U3. The samples of the measured voltage U1, U2, U3 are respectively denoted U1m, U2m, U3m, where m is a sample index varying between 1 and Ntotal_smp, Ntotal_smp being an integer representing the number of samples of a measured quantity X in the sampling window. The measured quantity X is, for example, the voltage U1, U2, U3 measured by the first device 60, or else the intensity 11 A, ..., I3N measured by the second device 62A as will be described subsequently.

The sampling window is, for example, chosen equal to one second.

The sampling period Psmp is equal to the ratio of the voltage period PVOitage and of a number Nsmp of samples of the quantity X measured per voltage period PVOitage-The sampling period Psmp satisfies the equation:

(1)

Where PVOitage is the period of the voltage, equal to the inverse of the frequency F of the voltage.

The number of samples per voltage period Nsmp is preferably an integer. The number of samples per voltage period Nsmp is, for example, equal to 36.

The memory 100 is able to store a first piece of software 104 for determining a first correlation table TABLE_1 and a second correlation table TABLE_2, on the basis of a measured value of the frequency F.

The first table TABLE_1 contains a plurality of first coefficients C\m. Preferably, the first table TABLE_1 contains Ntotal_smp first coefficients C\m. Each first coefficient C\m is a function of a cosine depending on the frequency F of the voltage.

The second table TABLE_2 contains a plurality of second coefficients C2,m· Preferably, the second table TABLE_2 contains Ntotal_smp second coefficients C2,m· Each second coefficient C2,m is a function of a sine depending on the frequency F of the voltage.

The memory 100 is able to store a first piece of software 105 for calculating a first set of at least one parameter for monitoring the voltage U1, U2, U3. The first set comprises for example a plurality of coefficients of a transform of the samples U1m, U2m, U3m of each measured voltage, up to a rank J of value greater than or equal to 1, preferably greater than or equal to 5, still preferably equal to 15. By convention, the rank equal to 1 corresponds to the fundamental of the transform.

In accordance with Shannon's theorem, the value of J must be less than or equal to (Nsmp/2)-1. The value of J will preferably be chosen equal to (Nsmp/2)-3. In the exemplary embodiment described, Nsmp is equal to 36, and the value of J is then equal to 15 with the aforementioned formula.

The memory 100 is able to store a first calculation piece of software 105 configured to calculate at least one parameter for monitoring the voltage U1, U2, U3 as a function of at least one measured value of the said voltage U1, U2, U3, preferably as a function of some of the values of the said voltage U1, U2, U3 measured in the course of a given emission period Pemission· The monitoring parameters comprise for example coefficients of a transform of the voltage values U1, U2, U3 measured.

The transform is, for example, a Fourier transform, and the first calculation piece of software 105 is suitable for calculating the real coefficient ReUjj and imaginary coefficient ImUjj of the Fourier series decomposition of the samples Uim of each measured voltage Ui, where i is an index of the corresponding phase, for example respectively equal to 1, 2 and 3, j is a rank of the Fourier series decomposition, with j lying between 1 and J, J being equal to the number of ranks of the said decomposition.

As a variant, the transform is a Laplace transform.

The memory 100 is able to store a first piece of software 106 for emitting a first message M1 destined for each second device 62A, ..., 62N. The instants of emission of two successive main messages M1 are separated by an emission period Remission-Each emission period Remission preferably exhibits a predetermined value, for example equal to one second. Preferably, the emission period Remission is chosen equal to the duration of the sampling window.

The number of samples Ntotal_smp is therefore equal to the number of samples in the emission period Remission- The number of samples Ntotal_smp is calculated according to the equation:

(2)

Each emission period Remission corresponds to a multiple NVOitage of voltage periods PVOitage, the voltage period PVOitage being equal to the inverse of the frequency F of the AC voltage U1, U2, U3. The multiple NVOitage is preferably an integer of value greater than or equal to 2, and the emission period Pemission then corresponds to an integer multiple of voltage periods PVOitage.

As a variant, the multiple NVOitage is a real number with value strictly greater than 1. According to this variant, a smoothing of the value of the samples of the measured intensity will then be performed so as to take into account this non-integer value of the multiple NVOitage-

The multiple NVOitage is calculated according to the equation:

(3)

The memory 100 is able to store a piece of software 107 for measuring the frequency F of the voltage. The measurement piece of software 107 is configured to calculate, for each emission period Pemission, the frequency F of the voltage on the basis of voltage samples U1m, U2m, U3m. The measurement piece of software 107 is able to store the calculated value of the frequency F in the memory 100 in the form of a stored value of the frequency Fst0. The measurement piece of software 107 is configured to transmit the value of the measured frequency F to the first sampling piece of software 103, to the first determination piece of software 104, to the first calculation piece of software 105 and to the first emission piece of software 106.

The memory 100 is able to store a piece of software 108 for distributing a unique token to the second devices 62A, ..., 62N in a successive manner.

When they are executed by the processor 98, the first acquisition piece of software 102, the first sampling piece of software 103, the first determination piece of software 104, the first calculation piece of software 105, the first emission piece of software 106, the measurement piece of software 107, and respectively the piece of software for distributing the distributed token 108 form a first module for acquiring values of the voltages U1, U2, U3 measured, a first module for sampling the values of the voltages U1, U2, U3 measured, a first module for determining a first correlation table TABLE_1 and a second correlation table TABLE_2, a first module for calculating a set of at least one parameter for monitoring the voltage, a first module for calculating at least one parameter for monitoring the voltage, a first module for emitting the first message M1, a module for measuring the frequency and respectively a module for distributing the distributed token.

As a variant, the first acquisition module 102, the first sampling module 103, the first determination module 104, the first calculation module 105, the first emission module 106, the measurement piece of software 107, and the module for distributing the distributed token 108 are embodied in the form of programmable logic components or else in the form of dedicated integrated circuits.

The radioelectric emitter-receiver 70 complies with the ZigBee communication protocol based on the IEEE-802.15.4 standard. As a variant, the radioelectric emitter-receiver 70 complies with the IEEE-802.15.1 standard, or with the IEEE-802.15.2 standard, or else with the IEEE-802-11 standard or else any other proprietary radio protocol.

The radioelectric antenna 72 is adapted for emitting radioelectric signals destined for the antennas 82A, ..., 82N of the second devices and for the antenna 94 of the centralization device, and also for receiving radioelectric signals from the said antennas 82A, ..., 82N, 94. Stated otherwise, the first device 60 is linked to each of the second devices 62A, ..., 62N and to the centralization device 64 by a corresponding radioelectric link.

The power supply module 74 is suitable for electrically supplying the measurement module 66, the information processing unit 68 and the radioelectric emitter-receiver 70 on the basis of the three-phase voltage flowing through the primary conductors 34, 36, 38.

Each sensor of the intensity 76A of the second device 62A is suitable for measuring a respective intensity from among a first intensity 11A flowing in the first secondary outlet conductor 42A, a second intensity I2A flowing in the second secondary outlet conductor 44A and a third intensity I3A flowing in the third secondary outlet conductor 46A.

Each sensor of the intensity 76A, also called a current sensor, comprises a first torus 110A disposed around the corresponding secondary outlet conductor 42A, 44A, 46A and a first winding 112A arranged around the first torus, as represented in Figure 3. The flow of the current through the corresponding secondary outlet conductor is suitable for causing an induced current proportional to the intensity of the current in the first winding 112A. The first torus 110A is a Rogowski torus. The first torus 110A is preferably an open torus so as to facilitate its arrangement around the corresponding conductors.

The information processing unit 78A, visible in Figure 2, comprises a data processor 114A, and a memory 116A associated with the data processor. The memory 116A is suitable for storing a second piece of software 118A for acquiring values of the respective intensities measured by each current sensor 76A, and a second piece of software 119A for sampling, with a sampling period Psmp, the value of the first, second and third intensities 11 A, I2A, I3A measured, and a piece of software 120A for receiving the first message M1.

The sampling window is, for example, chosen equal to the emission period P emission-

The samples of the first, second and third intensities 11 A, I2A, I3A measured are respectively denoted 11 Am, l2Am, l3Am where m is the sample index varying between 1 and Ntotal_smp.

The memory 116A is able to store a second piece of software 121A for calculating a second set of at least one parameter for monitoring the intensity 11 A, I2A, I3A. The second set comprises for example a plurality of coefficients of a transform of the samples MAm, l2Am, l3Am up to the rank J. The transform is, for example, a Fourier transform, and the second calculation piece of software 121A is suitable for calculating the real coefficient Re/^,y, and imaginary coefficient ImliAj of the Fourier series decomposition of the samples liAm of each measured intensity liA, where i is the index of the corresponding phase, j is the rank of the Fourier series decomposition, with j lying between 1 and J.

As a variant, the transform is a Laplace transform.

The memory 116A is able to store a piece of software 122A for synchronizing the sampling of the intensities 11 A, I2A, I3A measured with respect to the sampling of the measured voltage U1, U2, U3.

In the subsequent description, each voltage period is referenced with the aid of the index k. By convention, the voltage period of index k equal to 1 corresponds to the temporal period in the course of which the first message M1 is emitted by the first device 60 and respectively received by each second device 62A, ..., 62N, and the voltage period of index k equal to 2 corresponds to the period at the start of which the synchronization of the samplings of voltage and of intensities is performed.

The memory 116A is able to store a second determination piece of software 123A for determining the first correlation table TABLE_1 and the second correlation table TABLE_2, on the basis of a measured value of the frequency F.

The memory 116A is able to store a second piece of software 128A for emitting a second message M2A destined for the centralization device 64.

When they are executed by the processor 114A, the second acquisition piece of software 118A, the second sampling piece of software 119A, the reception piece of software 120A, the second calculation piece of software 121 A, the synchronization piece of software 122A, the second determination piece of software 123A and respectively the second emission piece of software 128A form a second module for acquiring values of the measured intensities, a second module for sampling the values of the measured intensities, a module for receiving the first message M1, a second calculation module for calculating at least one parameter for monitoring the intensity, a module for synchronizing the sampling of the intensities 11 A, I2A, I3A measured with respect to the sampling of the measured voltage U1, U2, U3, a second determination module, and respectively a second module for emitting the second message M2A.

As a variant, the second acquisition module 118A, the second sampling module 119A, the reception module 120A, the second calculation module 121 A, the synchronization module 120A, the second determination module 123A and the second emission module 128A are embodied in the form of programmable logic components or else in the form of dedicated integrated circuits.

The radioelectric emitter-receiver 80A is of the same type as the radioelectric emitter-receiver 70.

The radioelectric antenna 82A, of the same type as the radioelectric antenna 72, is adapted for receiving radioelectric signals from the antenna 72 of the first device and from the antenna 94 of the centralization device and also for emitting radioelectric signals to the antennas 72, 94.

The power supply module 84A, visible in Figure 3, is suitable for supplying the information processing unit 78A and the radioelectric emitter-receiver 80A. The power supply module 84A comprises, for each of the first 42A, second 44A and third 46A secondary conductors, a second torus 130A disposed around the corresponding secondary conductor 42A, 44A, 46A and a second winding 132A arranged around the second torus. The flow of the current in the corresponding secondary conductor 42A, 44A, 46A is suitable for causing an induced current in the second winding 132A.

The power supply module 84A comprises a converter 134A connected to each of the second windings 132A and suitable for delivering a predetermined voltage to the information processing unit 78A and to the radioelectric emitter-receiver 80A. Each second torus 130A is an iron torus. Each second torus 130A is preferably an open torus so as to facilitate its arrangement around the corresponding conductors.

Stated otherwise, the second device 62A is self-supplied by way of the power supply module 84A comprising the second tori 130A adapted for recovering the magnetic energy arising from the flow of the current in the corresponding secondary conductors 42A, 44A, 46A.

The elements of the other second devices 62B, ..., 62N are identical to the previously described elements of the first second device 62A, and comprise the same sub-elements, each time replacing the letter A by the corresponding letter B, ..., N relating to the references of the sub-elements.

The information processing unit 86 of the centralization device, visible in Figure 2, comprises a data processor 136, and a memory 138 associated with the processor. The memory 138 is able to store a piece of software 140 for receiving the second messages M2A,..., M2N, a piece of software 142 for recording in the database 88 information contained in the messages M2A,..., M2N received. The memory 138 is suitable for storing a piece of software 144 for processing the said information received, a piece of software 146 for displaying data and a piece of software 148 for transmitting data destined for a remote server, not represented. The processing piece of software 144 is in particular configured to calculate the electrical energy E, of the AC current flowing in each secondary electrical conductor 42A, ..., 46N on the basis of the monitoring parameters calculated by the first monitoring device 60 and by each second monitoring device 62A, ..., 62N, these calculated monitoring parameters being contained in the data messages M2A, ..., M2N received.

When they are executed by the processor 136, the reception piece of software 140, the recording piece of software 142, the processing piece of software 144, the display piece of software 146, and respectively the transmission piece of software 148 form a module for receiving the second messages M2A,..., M2N, a module for recording in the database 88 information contained in the messages M2A,..., M2N received, a module for processing the said information received, a module for displaying data and a module for transmitting data destined for a remote server.

As a variant, the reception module 140, the recording module 142, the processing module 144, the display module 146, and the transmission module 148 are embodied in the form of programmable logic components or else in the form of dedicated integrated circuits.

The man-machine interface 90 comprises a display screen and an input keyboard, neither of which is represented.

The radioelectric emitter-receiver 92 is of the same type as the radioelectric emitters-receivers 70, 80A, ..., 80N.

The radioelectric antenna 94, of the same type as the radioelectric antennas 72, 82A, ..., 82N, is suitable for receiving radioelectric signals arising from the antenna 72 of the first device and antennas 82A, ..., 82N of the second devices and also for emitting radioelectric signals destined for the said antennas 72, 82A, ..., 82N.

The operation of the monitoring system 20 will henceforth be explained with the aid of Figures 4, 5 and 6 representing flowcharts of the steps of a monitoring method which are implemented respectively by the first device 60, by the second devices 62A, ..., 62N and by the centralization device 64.

As represented in Figure 4, during a first step 200, the first device 60 initializes itself, and the stored value Fst0 of the frequency F is fixed equal to the nominal value of the frequency Fn0m by the measurement piece of software 107 during the initialization step 200. The nominal value of the frequency Fn0m is defined as being the inverse of the nominal voltage period Pn0m·

The nominal voltage period Pn0m is equal to 20 ms in Europe and 16.66 ms in the United States.

The first sampling piece of software 103 calculates the sampling period Psmp according to equation (1), by considering that the voltage period PVOitage is equal to the nominal period of the voltage Pn0m· The sampling period Psmp therefore satisfies the equation:

(4)

The first determination piece of software 104 determines, furthermore, the first correlation table TABLE_1 containing Ntotal_smp first coefficients C\m, and the second table TABLE_2 containing Ntotal_smp second coefficients C\m.

Each first coefficient C1j,m is a function of a cosine depending on the frequency F of the voltage. Each second coefficient C\m is a function of a sine depending on the frequency F of the voltage.

Each first coefficient C\m satisfies, for example, the equation: C-m =cos(2xnxF xjxtnxPsmp), (5) and each second coefficient C\m satisfies, for example, the equation: C-,m =sin(2xUxFxjxmxPsmp) (6) where j lies between 1 and J, J being an integer preferably greater than or equal to 5, preferably equal to 17, F is the frequency value of the voltage measured during the penultimate emission period Remission; if no value F of the frequency has yet been measured, the value F of the frequency is taken equal to the inverse of the nominal period of the current; this may be written mathematically: F=1/Pn0m, and m is the sample index varying between 1 and Ntotal_smp.

The measurement piece of software 107 transmits to the first sampling piece of software 103, to the first determination piece of software 104, to the first calculation piece of software 105, and to the first emission piece of software 106, during the following step 205, the value stored Fst0 in the measurement piece of software 107.

When step 205 is preceded immediately by the initialization step 200, the stored value Fst0 is equal to the nominal value of the frequency Fn0m·

When step 205 is preceded by step 230 corresponding to a previous emission period Remission, the stored value Fst0 is equal to the value of the frequency F measured during the penultimate emission period Pemission·

During the following step 208, the sampling period Psmp is recalculated by the first sampling piece of software 103 as a function of the value of the frequency F of the three-phase voltage transmitted by the measurement piece of software 107. Stated otherwise, the sampling period Psmp is calculated on the basis of the value of the frequency F, knowing that the product of the sampling period Psmp and of the frequency F is equal to a predetermined constant.

It is not necessary to recalculate the first table TABLE_1 and the second table TABLE_2 since the product of the frequency F and of the sampling period Psmp is unchanged, the sampling period Psmp having been recalculated by considering that the product of the frequency F and of the sampling period Psmpis constant.

The voltage period PVOitage corresponds to a multiple of the sampling period Psmp, in accordance with equation (2) hereinabove.

The first device 60 measures thereafter, during step 210, the first, second and third voltages U1, U2, U3 with the aid of its measurement module 66 and of its first acquisition piece of software 102. The first device 60 measures the first, second and third voltages U1, U2, U3 for a duration equal to the emission period Pemission- The first sampling piece of software 103 then samples the measured values of the voltages U1, U2, U3 according to the sampling period Psmp, calculated during step 208.

The value F of the voltage frequency is measured regularly during the emission period Remission, and the stored value of the frequency Fst0 is updated. This signifies that the stored value of the frequency Fst0 is fixed equal to the value F of the measured frequency.

The measurement piece of software 107 calculates, for each sample Ui,m, the real part RePi,m and imaginary part lmPi,m of a corresponding voltage phasor Pi,m according to the equations:

(7) (8)

The calculation of the real part RePi,m and imaginary part lmPj,m of the voltage phasor Piim are therefore calculated, for each voltage sample Ui,m, on the basis of the voltage samples Uj,m acquired during the last voltage period.

The measurement piece of software 107 measures thereafter, with a measurement period Pmeasure, the angular difference Δφ between two voltage phasors Pi,mi and Pi,m2 corresponding to two temporal instants separated by a measurement period Pmeasure, by the equation:

(9)

The measurement period Pmeasure is, for example, substantially equal to half the voltage period PVOitage-

The value F of the frequency is then calculated according to the equation:

(10)

The value F of the frequency is therefore calculated at each measurement period Pmeasure-

Each measurement period Pmeasure will subsequently be referenced by an index z.

After each measurement period P^es, the measurement piece of software 107 compares the sign of the angular difference Δφ calculated during the measurement period of index z with the signs of the angular differences Δφ calculated during the previous measurement periods. Preferably, the measurement piece of software 107 compares the sign of the angular difference Δφ calculated during the measurement period of index z with the signs of the angular differences Δφ calculated during the previous 9 measurement periods.

If the sign of the angular difference Δφ has remained constant during the 10 measurement periods Pmz;s9 to p^s, the value of the stored frequency Fst0 is fixed equal to the value of the frequency F measured during the measurement period of index z. Otherwise, the value of the stored frequency Fst0 remains unchanged.

If the absolute value of the difference between the value of the stored frequency Fst0 and the value of the measured frequency F is greater than a predefined value Vp, for example 5 Flertz (Hz), and the value of the stored frequency Fst0 is greater than the value of the measured frequency F, the value of the stored frequency Fst0 is decreased by the predefined value Vp. This may be written mathematically Fst0:= Fst0 -Vp.

If the absolute value of the difference between the value of the stored frequency Fst0 and the value of the measured frequency F is greater than a predefined value Vp, for example 5 Flertz (Hz), and the value of the stored frequency Fst0 is less than the value of the measured frequency F, the value of the stored frequency Fst0 is increased by the predefined value Vp. This may be written mathematically Fst0:= Fst0 +Vp.

The value of the stored frequency Fst0 is bounded. This signifies that, if the value of the measured frequency F is less than a predefined lower bound Bi, the stored frequency Fst0 is fixed equal to the value of the lower bound Bi. This may be written mathematically Fst0:= Bi. For example, the lower bound Bi is equal to 40 Hz.

If the value of the F measured is greater than a predefined upper bound Bs, the stored frequency Fst0 is fixed equal to the value of the upper bound Bs. This may be written mathematically Fst0:= Bs. For example, the upper bound Bs is equal to 70 Hz.

The stored value Fst0 is transmitted to the first sampling piece of software 103, to the first determination piece of software 104, to the first calculation piece of software 105, and to the first emission piece of software 106, during step 205.

During step 220, the first device 60 calculates a set of parameters for monitoring the voltages U1, U2, U3. The parameters for monitoring the voltage comprise coefficients of a transform of the measured voltages U1, U2, U3.

The first device 60 therefore compresses the measured values of the voltages U1, U2, U3 by determining real ReUjj, and imaginary \mUij coefficients of the Fourier series decomposition of the samples Uim of each measured voltage U1, U2, U3 with the aid of its first calculation piece of software 105. This makes it possible to limit the amount of data transmitted by way of the radioelectric links between the first device 60 and the centralization device 64.

The coefficients ReUjj, ImUjj of the Fourier series decomposition are, for example, obtained through a correlation between the samples of the measured values and the coefficients C\m, C2j,m contained in the first table TABLE_1 and respectively the second table TABLE_2. The coefficients ReUjj, ImU/jof the Fourier series decomposition are therefore calculated just once for the whole of the emission period Remission- The coefficients ReUjj, \mUij of the Fourier series decomposition are calculated by products of vectors between the tables TABLE_1, TABLE_2 and a vector containing the voltage samples. The calculation of the coefficients Rel/y, Im Ujj of the Fourier series decomposition is therefore simplified.

More precisely, the real coefficient of the fundamental, denoted ReUj,i, is a correlation, over a duration equal to the emission period Remission, between the samples Uim of the voltage signal Ui and a cosine of frequency equal to the frequency F of the three-phase voltage, where Ui represents the voltage of the phase, i being equal to 1, 2 or 3. The imaginary coefficient of the fundamental, denoted ImUjj, is a correlation, over a duration equal to the emission period Remission, between the samples U,m of the voltage signal Ui and a sine of frequency equal to the frequency F.

The real coefficient of the harmonic of rank j, denoted ReU/j, j lying between 2 and J, is the correlation, over a duration equal to the emission period Remission, between the samples Ui,m of the voltage signal Ui and a cosine of frequency equal to j times the frequency F. The imaginary coefficient of the harmonic of rank j, denoted

Irnl/y, is the correlation, over a duration equal to the emission period Remission, between the samples Uim of the voltage signal Ui and a sine of frequency equal to j times the frequency F.

Stated otherwise, the coefficients ReUjj and Im Ujj satisfy the following equations, j lying between 1 and J:

(11) (12)

As a variant, the coefficients ReUjj and Im Ujj are obtained by a fast Fourier transform (FFT).

The first calculation piece of software 105 thus calculates the complex coefficients ReUjj and Im Ujj of the Fourier series decompositions of the three voltages U1, U2, U3 for the fundamental and the harmonics 2 to J.

Finally, during step 230, the first device 60 emits, with the aid of its emission piece of software 106, the first message M1 destined for each of the second devices 62A, ..., 62N. The first message M1 contains the complex coefficients ReUjj and Im Ujj, calculated during step 220, of the Fourier series decompositions of the three voltages U1, U2, U3, for the whole of the emission period Remission-

The first device 60 furthermore launches, during this step 230, a first timespan equal to a reference duration Df, counting from the instant of start of emission of the first message M1, also called the emission pip Te of the first message M1. When this first timespan elapses, the first device 60 will then start the sampling of the measured values of the three voltages U1, U2, U3, that is to say at a start-of-sampling instant Tm equal to the instant of start of emission Te plus the reference duration Df. The sampling, by the second device 62A, of the measured values of the three intensities 11 A, I2A, I3A will also begin at this start-of-sampling instant Tm, as will be described in greater detail subsequently with regard to the synchronization step 320.

The reference duration Df has a predetermined value, for example substantially equal to 6 ms. The value of the reference duration Df is known both to the first device 60 and to the second device 62A, and is chosen greater than the duration necessary for the emission and reception of the first message M1. In the exemplary embodiment described, the value of the reference duration Df is stored, prior to the initial step 200, in the memory 100 of the first device and in the memory 116A of the second device 62A.

The first message M1 comprises a header field, also called the preamble, an SFD (Start of Frame Delimiter) field, a PFIR (Physical Header) field, a data field and a CRC (Cyclic Redundancy Check) field. The preamble exhibits a size of 4 bytes, the SFD and PHR fields each exhibit a size of a byte, the data field is of variable size, denoted n bytes, and the CRC field has a size of 2 bytes. In the exemplary embodiment of Figure 7, the first message M1 consists of the header field, of the SFD field, of the PHR field, of the data field and of the CRC field.

The data field of the first message M1 contains the value of the frequency F transmitted during step 205, the identifier of the second device which will be authorized to emit its second message destined for the centralization device 64 after the reception of the first message M1, as well as the value of the reference duration Df in case of modification of the latter. The identifier of the second device authorized to emit its measurement information is determined with the aid of the piece of software for distributing the unique token 108, the identifier of the second device contained in the first message M1 making it possible to designate the second device to which the unique token has been allotted.

When the message M1 is dispatched, steps 205 to 230 are repeated in this order. The measurement module 107 therefore transmits a new value of the frequency F to the first calculation module 105.

The steps of the monitoring method which are visible in Figure 5 and are implemented by the second devices 62A, ..., 62N will be now described for the second device with the reference 62A.

During step 300, the second device 62A initializes itself and opens a sliding window for receiving the first message M1 with the aid of its reception piece of software 120A. The reception window is a window exhibiting a duration of a few tens of milliseconds which is made to slide over time by the second device 62A.

The second determination piece of software 123A calculates, furthermore, the first correlation table TABLE_1 and the second correlation table TABLE_2 according to equations (5) and (6).

During the reception of the first message M1 in the course of step 310, the second device 62A detects the instant Tr of reception of the SFD field, the reception of the SFD field bringing about the triggering of an interruption by the radioelectric receiver of the second device 62A, as represented in Figure 7.

During the following step 315, the sampling period Psmp is calculated by the second sampling piece of software 119A as a function of the value of the frequency F contained in the last message M1 received. This step is analogous to step 208 described previously, the sampling period Psmp satisfying equation (1).

The voltage period PVOitage is thus recalculated, by the second sampling piece of software 119A, on each reception of first message M1 with the aid of the value of the voltage frequency F contained in the first message M1.

The second device 62A thereafter passes to the step 320 of temporal synchronization with the first device 60. The detection of the instant of reception Tr makes it possible to calculate, with the aid of the synchronization piece of software 122A, the instant Tm of start of the sampling of the measured values of the three intensities 11 A, I2A, I3A. The instant of start of the sampling Tm is indeed equal to the instant of reception Tr plus a synchronization duration Dm, the synchronization duration Dm being equal to the reference duration Df minus a radio transmission duration Dr, as represented in Figure 7. The radio transmission duration Dr is a value dependent on the radioelectric emitter-receiver 70 and on the radioelectric emitter-receiver 80A. The radio transmission duration Dr corresponds to the temporal period between the instant of start of emission Te and the instant of reception Tr.

The radio transmission duration Dr is for example substantially equal to 0.6 ms, and is known to the second device 62A. In the exemplary embodiment described, the value of the radio transmission duration Dr is stored, prior to step 300, in the memory 116A of the second device 62A.

The second device 62A then launches, from the instant of reception Tr and with the aid of the synchronization piece of software 122A, a second timespan equal to the synchronization duration Dm, the value of the synchronization duration Dm being calculated by subtracting the value of the radio transmission duration Dr from the value of the reference duration Df, the value of the radio transmission duration Dr and the value of the reference duration Df being stored in the memory 116A as described previously.

The first device 60 had moreover launched, during step 230, the first timespan equal to the reference duration Df, so that the first device 60 and the second device 62A will simultaneously begin the sampling of the measured voltage values, and respectively of the measured intensity values, when the first and second timespans launched in steps 230 and 320 have elapsed, that is to say at the start-of-sampling instant Tm.

By convention, the voltage period corresponding to the emission of the first message M1 is the period of index k equal to 1. When the first message M1 has also been received in the course of the voltage period of index k equal to 1, the start-of-sampling instant subsequent to the synchronization then corresponds to the start of the voltage period of index k equal to 2.

During step 320, the synchronization piece of software 122A initializes, to the date of reception of the first message M1, a meter intended to be incremented up to a value corresponding to the period of emission of the first message Remission- The second device 62A then automatically returns to the reception step 310 about a millisecond before the expected reception of the next first message M1.

If the first message M1 is not detected by the second device 62A, the reception window is reclosed and no synchronization is performed. The meter is then incremented for a new attempt at synchronization with the following probable message M1.

The second device 62A then measures, during step 330 and by way of its current sensors 76A and of its second acquisition piece of software 118A, each of the first, second and third intensities 11 A, I2A, I3A.

The second sampling piece of software 119A thereafter samples the measured values of the three intensities 11 A, I2A, I3A, the instant of start of the sampling Tm having been calculated during the previous step 320 so as to ensure the temporal synchronization of the sensor of the intensity 76A with respect to the apparatus for measuring the voltage 66.

The second device 62A thereafter calculates, during step 340, a set of parameters for monitoring each measured intensity 11 A, I2A, I3A. The parameters for monitoring each measured intensity 11 A, I2A, I3A comprise coefficients of a transform of the measured intensities 11 A, I2A, I3A.

The second calculation piece of software 121A therefore compresses the measured values of the intensities 11 A, I2A, I3A by calculating, for example, the real ReliAj, and imaginary Im/^y coefficients of the Fourier series decomposition of the samples liAm of each measured intensity 11 A, I2A, I3A of the three phases in a manner analogous to the calculation, described for step 220, of the complex coefficients ReUij, Im Ujj of the Fourier series decomposition of the voltages. The real ReliAj, and imaginary Im/^y coefficients are therefore calculated just once for the entirety of the emission period Remission-

The coefficients Re/^,y, ImliA,j of the Fourier series decomposition are, for example, obtained through a correlation between the samples of the measured values and the coefficients C\m, C\m contained in the first table TABLE_1 and respectively the second table TABLE_2. The coefficients ReliAj, Im/z^of the Fourier series decomposition are therefore calculated just once for the whole of the emission period Remission- The coefficients ReliAj, Im/^yOf the Fourier series decomposition are calculated by products of vectors between the tables TABLE_1, TABLE_2 and a vector containing the intensity samples. The calculation of the coefficients ReliAj, Im/^yOf the Fourier series decomposition is therefore simplified.

The real coefficient of the fundamental, also denoted Re/^y, is thus a correlation, over a duration equal to the emission period Remission, between the samples of the signal of the intensity liA and a cosine of frequency equal to the frequency F of the three-phase voltage, where liA represents the intensity of phase number i, i being equal to 1, 2 or 3. The imaginary coefficient of the fundamental, also denoted ImliA,i, is a correlation, over a duration equal to the emission period Remission, between the samples of the signal of the intensity liA and a sine of frequency equal to the frequency F.

The real coefficient of the harmonic of rank j, denoted ReliAj, j lying between 2 and J, is the correlation, over a duration equal to the emission period Remission, between the samples of the signal of the intensity liA and a cosine of frequency equal to j times the frequency F. The imaginary coefficient of the harmonic of rank j, denoted Im/^y, j lying between 2 and J, is the correlation, over a duration equal to the emission period Remission, between the samples of the signal of the intensity liA and a sine of frequency equal to j times the frequency F.

The coefficients ReliAj, and lm//4,y then satisfy the following equations:

(13)

(14)

The second calculation piece of software 121A thereafter calculates the active power Pij,An associated with each rank j of the Fourier series decomposition by virtue of the equation:

(15)

The second calculation piece of software 121A also calculates the active energy Eij,An associated with each rank j of the Fourier series decomposition by virtue of the equation according to the equation:

Ei,j,A ~ Femission X ^i.j.A 0 6)

The second calculation piece of software 121A thereafter calculates the active energy Ei,A of each of the three phases on the basis of the Fourier coefficients of the voltage and of the intensity according to the equation:

(17)

The second device 62A then formulates, during step 350, its second message M2A. The second message M2A contains the values of the active energy E,,A of each phase which were calculated in the course of step 340.

Under the assumption that the identifier of the second device 62A was contained in the first message M1 received previously, the second device 62A then emits during step 360 its second message M2A with the aid of its emission piece of software 128A. In the converse case, the second device 62A returns directly to step 310 of receiving the first message M1, and will emit its second message M2A when the first message M1 contains its identifier thus indicating that the unique token had been allotted to it so as to authorize it to emit its second message M2A.

After the emission step 360 in the case where the token had been allotted to the second device 62A, or else after step 340 otherwise, the second device 62A returns to the reception step 310 if the meter has attained the value corresponding to the emission period Remission, or else to the measurement step 330 otherwise.

The steps of the monitoring method which are implemented by the other second devices 62B, ..., 62N are identical to steps 300 to 360 described previously for the second device with the reference 62A, and are carried out furthermore in a manner that is simultaneous between all the second devices 62A, ..., 62N on account of the temporal synchronization performed with the aid of the first message M1.

During the emission step 360, the only second device out of the set of second devices 62A,..., 62N which is authorized to emit its second message is the second device whose identifier is contained in the first message M1 received during the previous reception step 310. The distribution piece of software 108 determines according to an ascending order the identifiers contained in the first message M1 so as to successively allot the unique token to the second devices 62A, ..., 62N. Stated otherwise, each second device 62A, ..., 62N emits its respective second message M2A, ..., M2N every N seconds.

As represented in Figure 6, during step 400, the centralization device 64 receives, with the aid of its reception piece of software 140, the second message of the second device authorized to emit according to the distributed token-based mechanism, for example the message M2A.

During step 410, the centralization device 64 thereafter records in its database 88 the values received and contained in the second message M2A, by way of its recording piece of software 142. As a supplement, the processing piece of software 144 performs a time-stamping of the recorded data.

During step 410, the centralization device 64 thereafter records in its database 88 the values received and contained in the first message M1 and in the second message M2A, by way of its recording piece of software 142. As a supplement, the processing piece of software 144 performs a time-stamping of the recorded data.

The quantities measured and calculated by the monitoring system are thereafter displayed on the screen of the man-machine interface 90 of the centralization device by way of the display piece of software 146 during step 430. These quantities are displayed in the form of numerical values and/or in the form of curves.

The centralization device 64 finally transmits, during step 440 and with the aid of its transmission piece of software 148, these measured and calculated quantities to the remote server, not represented. The remote server is suitable for performing centralized management of the quantities measured and calculated for each monitoring system 20.

On completion of step 440, the centralization device 64 returns to step 400, so as to receive the second message of the second device authorized to emit the next time according to the distributed token-based mechanism, for example the message M2A.

The monitoring system 20 according to the invention thus makes it possible to calculate the active energies E-ι, E2, E3 directly over the given emission period Pemission and as a function of the values of the voltage for the whole of the emission period, and not only of the values of the voltage measured for a single selected voltage period.

The monitoring system 20 according to the invention is thus more accurate than the monitoring system of the prior art.

The monitoring system 20 is furthermore suitable for the measurement of electrical energy even in the case where the frequency F of the voltage is not constant.

The monitoring system 20 according to the invention furthermore makes it possible to obtain a very accurate measurement of the active energies E, for the three phases of the three-phase current, on account of the temporal synchronization of each current sensor 76A with respect to the module for measuring the voltage 66.

The temporal synchronization is very accurate, the synchronization offset measured being of the order of plus or minus 400 nanoseconds with the present technology of the radioelectric emitters-receivers 70, 80A, ..., 80N, 92 and of the information processing units 68, 78A, ..., 78N, 86.

The set of devices 60, 62A, ..., 62N, 64 are linked together by radioelectric links by way of their respective radioelectric emitter-receiver 70, 82A,..., 82N, 92, thereby making it possible to facilitate the installation of the monitoring system 20 in the transformation substation 10.

According to a second embodiment, the sampling period Psmp is constant. The sampling period Psmp is then calculated by virtue of the equation:

(18)

The first correlation table TABLE_1 and the second correlation table TABLE_2 are not calculated during step 200 but during step 208. The first correlation table TABLE_1 and the second correlation table TABLE_2 are then recalculated during each emission period Pemission by using the last value of the frequency F transmitted by the measurement piece of software 107.

During the following step 315, the second determination piece of software 123A calculates, furthermore, the first correlation table TABLE_1 and the second correlation table TABLE_2 according to equations (2) and (3). This step is analogous to step 208 described previously.

The other steps of the manner of operation of this second embodiment are identical to those of the first embodiment.

The advantages of this second embodiment are similar to those of the first embodiment. The monitoring system 20 makes it possible, moreover, to use first and second sampling modules 103, 119A whose sampling period is fixed.

According to a third embodiment, described in Figure 9, during step 300, the real Re/^,y, and imaginary ImI/aj coefficients of the Fourier series decomposition of the samples liAm of each measured intensity 11 A, I2A, I3A of the three phases are calculated for each voltage period PVOitage-

The second determination piece of software 123A therefore determines a third correlation table TABLE_3 containing a plurality of first coefficients C\m and a fourth correlation table TABLE_4 containing a plurality of second coefficients C\m- Each of the third table TABLE_3 and of the fourth table TABLE_4 then contains Nsmp coefficients C1j,m, C2j,m.

Each first coefficient C\m satisfies the previous equation (5), and each second coefficient C\m satisfies the previous equation (6), m varying between 1 and Nsmp.

During step 330, the samples of the first, second and third measured intensities 11 A, I2A, I3A are respectively denoted HAm,k, l2Am,k, l3Am,k where k is the index of the voltage period PVOitage and m is the sample index varying between 1 and Nsmp.

During step 340, the second calculation piece of software 121A therefore calculates, for each voltage period of index k, the real Re/^/k, and imaginary ImliA,j,k coefficients of the Fourier series decomposition of the samples liAm,k of each measured intensity 11 A, I2A, I3A of the three phases according to the following equations:

(21)

(22)

The second calculation piece of software 121A thereafter calculates the active power Pij,A associated with each rank j of the Fourier series decomposition by virtue of the equation:

(23)

The second calculation piece of software 121A also calculates the active energy E^a associated with each rank j of the Fourier series decomposition by virtue of the equation according to the equation:

(24)

The second calculation piece of software 121A thereafter calculates the active energy Ei,A of each of the three phases on the basis of the Fourier coefficients of the voltage and of the intensity according to equation (17).

The other steps of the manner of operation of this third embodiment are identical to the steps of the first embodiment.

The advantages of this third embodiment are similar to those of the first embodiment.

The monitoring system 20 then makes it possible to calculate the active energies Ei, E2, E3 corresponding to each voltage period of index k. The monitoring system 20 is therefore suitable for the monitoring of installations which are both producers or consumers of current, and which pass from the consumer status to the producer status, and conversely from the producer status to the consumer status, for durations of less than the emission period Remission-

Claims

1.- Electronic device (60; 62A, ..., 62N) for monitoring an electrical quantity (X) from among a voltage (U1, U2, U3) and an intensity (11 A, ..., I3N) relating to an AC current flowing in an electrical conductor (34, 36, 38; 42A, 44A, 46A, ..., 42N, 44N, 46N), the AC current comprising at least one phase, the device comprising: - a measurement module (66; 76A, ..., 76N) configured to measure at least one value of the electrical quantity (X), - a module (103; 119A,...,119N) for sampling the value of the measured electrical quantity (X), - a radioelectric emitter-receiver (70; 80A, ..., 80N), - an emission module (106; 128A, ..., 128N) linked to the radioelectric emitter-receiver (70; 80A, ..., 80N), the emission module (106; 128A, ..., 128N) being configured to emit destined for another electronic device, with an emission period (Pemission), a data message (M1; M2A, ..., M2N) containing a set of at least one parameter for monitoring the measured quantity (X), characterized in that it furthermore comprises a module (104; 123A,...,123N) for determining a first table (TABLE_1) and a second table (TABLE_2), and a module (105; 121 A,.. .,121N) for calculating at least one parameter for monitoring the quantity (X) on the basis of the first table (TABLE_1), of the second table (TABLE_2), and of samples of the quantity (X), arising from the sampling module (103, 119A ..., 119N), the first table (TABLE_1) containing a plurality of first coefficients (C\m), each first coefficient (C\m) being a function of a cosine and depending on the frequency (F) of the voltage of the electrical conductor (34, 36, 38; 42A, 44A, 46A, ..., 42N, 44N, 46N), and the second table (TABLE_2) containing a plurality of second coefficients (C2j,m), each second coefficient (C2j,m) being a function of a sine and depending on the said frequency (F), the number of coefficients (C\m, C2,m) of each table (TABLE_1, TABLE_2) being equal to the number of samples of the quantity (X) during the emission period (P emission)·

2. - Device according to Claim 1, in which the first coefficients (C\m) satisfy the equation: C‘m =cos(2xIIxFx jxmxPsmp), and the second coefficients (C2j,m) satisfy the equation: C^,m = sin(2 xIIxFxyxmx Psmp) where j lies between 1 and J, J being an integer, preferably greater than or equal to 5, Psmp is the sampling period for the quantity (X), and m is a sample index varying between 1 and Ntotal_smp, Ntotal_smp being an integer representing the number of samples of the quantity (X) during the emission period (Pemission)·

3. - Device (60; 62A, ..., 62N) according to Claim 1 or 2, in which the determination module (104; 123A, ...,123N) is suitable for recalculating, during each emission period (Pemission), the first table (TABLE_1) and the second table (TABLE_2) on the basis of a value of the frequency (F) measured during the penultimate emission period (Pemission)·

4. - Device (60; 62A, ..., 62N) according to any one of Claims 1 to 3, in which the sampling module (103; 119A,...,119N) is able to sample the electrical quantity (X) with a sampling period (Psmp), and the value of the sampling period (Psmp) is dependent on a value of the frequency of the voltage (F) measured during the penultimate emission period (Pemission)·

5. - Device (60) according to any one of Claims 1 to 4, in which the device (60) is adapted for monitoring the voltage (U1, U2, U3) of the electrical conductor (34, 36, 38), the measurement module (66) is configured to measure the frequency (F) of the voltage, and the message emitted (M1) furthermore contains a measured value of the frequency (F) of the voltage.

6. - Device (60) according to Claim 5, in which the measurement module (66) is configured to calculate, for each voltage sample (Ui,m), the real part (RePi,m) and imaginary part (lmPiim) of a corresponding voltage phasor (Piim) satisfying the equations:

where Nsmp is the number of voltage samples acquired during a voltage period (PVOitage)> the voltage period (PVOitage) being equal to the inverse of the frequency (F), and to measure, with a measurement period (Pmeasure), a value of the frequency (F) on the basis of two voltage phasors (Pj,m) corresponding respectively to two temporal instants separated temporally by a measurement period (Pmeasure)·

7. - Device (60) according to Claim 6, in which the measurement period (Pmeasure) is substantially equal to half the voltage period (Pvoitage)·

8. - Device (62A, ..., 62N) according to any one of Claims 1 to 4, in which the device (62A, ..., 62N) is adapted for monitoring an intensity (11 A, ..., I3N), and comprises a reception module (120A,...,120N) for a data message (M1) comprising a measured value of the frequency (F) of the voltage.

9. - Electronic system (20) for monitoring an electrical panelboard (16) comprising at least one primary electrical outlet conductor (34, 36, 38) and at least one secondary electrical outlet conductor (42A, ..., 46N), the or each secondary outlet conductor (42A, ..., 46N) being connected electrically to a corresponding primary outlet conductor (34, 36, 38), the corresponding outlet conductors (34, 42A, 42B,.., 38, 46A, 46B, ..., 46N) exhibiting an AC voltage, the system comprising: - a first electronic device (60) for monitoring the voltage (U1, U2, U3) of each primary electrical outlet conductor (34, 36, 38), - at least one second electronic device (62A, ..., 62N) for monitoring the intensity (11 A, ..., I3N) of the AC current flowing in each secondary electrical conductor (42A, ..., 46N), characterized in that at least one electronic monitoring device (60, 62A, ..., 62N) complies with any one of the preceding claims.

10. - System (20) according to Claim 9, in which each electronic monitoring device (60; 62A, ..., 62N) complies with any one of Claims 1 to 4.

11. - System (20) according to Claim 9 or 10, in which the first monitoring device (60) complies with any one of Claims 5 to 7, and each second monitoring device (62A, ..., 62N) complies with Claim 8.

12. - System (20) according to Claim 9, in which the first monitoring device (60) complies with any one of Claims 1 to 7, and each second monitoring device (62A, ..., 62N) comprises a determination module (123A,...,123N) able to calculate a third correlation table (TABLE_3) and a fourth correlation table (TABLE_4), the third table (TABLE_3) containing a plurality of the first coefficients (C1j,m), and the fourth table (TABLE_4) containing a plurality of the second coefficients (C j,m), the number of coefficients (C\m, C2j,m) of each table (TABLE_3, TABLE_4) being equal to the number of samples of the quantity (X) during a corresponding voltage period (PVOitage)·

13. - Electrical cabinet, comprising: - an electrical panelboard (16) comprising at least one primary electrical outlet conductor (34, 36, 38) and at least one secondary electrical outlet conductor (42A, ..., 46N), the or each secondary outlet conductor (42A, ..., 46N) being connected electrically to a corresponding primary outlet conductor (34; 36; 38), the corresponding outlet conductors (34, 42A, 42B,.., 38, 46A, 46B, ..., 46N) exhibiting an AC voltage, and - a system (20) for monitoring the electrical panelboard (16), characterized in that the monitoring system (20) complies with any one of Claims 9 to 12.

14. - Substation (10) for transforming an electric current exhibiting a first AC voltage into an electric current exhibiting a second AC voltage, characterized in that it comprises an electrical cabinet according to Claim 13, an inlet panelboard (14) comprising at least one electrical inlet conductor (24A, 26A, 28A, 24B, 26B, 28B) suitable for being linked to an electrical network (12), the inlet conductor exhibiting the first AC voltage, the panelboard (16) of the cabinet forming an outlet panelboard whose corresponding outlet conductors (34, 42A, 42B,.., 38, 46A, 46B, ..., 46N) exhibit the second AC voltage, and an electrical transformer (18) connected between the inlet panelboard (14) and the outlet panelboard (16), the transformer (18) being suitable for transforming the current exhibiting the first AC voltage into the current exhibiting the second AC voltage.

15. Method for monitoring an electrical quantity (X) from among a voltage (U1, U2, U3) and an intensity (11 A, ..., I3N) relating to an AC current flowing in an electrical conductor (34, 36, 38; 42A, 44A, 46A, ..., 42N, 44N, 46N), the AC current comprising at least one phase, the method being implemented by an electronic monitoring device (60; 62A, ..., 62N), and comprising the following steps: - b) the measurement (210; 330) of at least one value of the electrical quantity (X) and the sampling of the measured value (X), - d) the emission (230; 350), with an emission period (Remission), of a data message (M1; M2A, ..., M2N) containing a set of at least one parameter for monitoring the measured quantity, destined for another electronic device (62A, ..., 62N; 60; 64), characterized in that it furthermore comprises, prior to step b), the following step: - a) the determination of a first table (TABLE_1) and of a second table (TABLE_2), the first table (TABLE_1) containing a plurality of first coefficients (C\m), each first coefficient (C\m) being a function of a cosine and depending on the said frequency (F) of the voltage of the electrical conductor (34, 36, 38; 42A, 44A, 46A, ..., 42N, 44N, 46N), and the second table (TABLE_2) containing a plurality of second coefficients (C2j,m), each second coefficient (C2j,m) being a function of a sine and depending on the said frequency (F), and the number of coefficients (C\m, C2,m) of each table (TABLE_1, TABLE_2) being equal to the number of samples of the quantity (X) during the emission period (P emission) j and in that it comprises, furthermore, after step b) and prior to step d), the following step: - c) the calculation of at least one parameter for monitoring the quantity (X) on the basis of the first table (TABLE_1), of the second table (TABLE_2), and of samples of the quantity (X), obtained during step b).