WO2003096568A1

WO2003096568A1 - Telecommunication network on electric power transmission line

Info

Publication number: WO2003096568A1
Application number: PCT/FR2003/001326
Authority: WO
Inventors: Jean-Pierre Lobert
Original assignee: Defidev
Priority date: 2002-05-02
Filing date: 2003-04-28
Publication date: 2003-11-20
Also published as: FR2839402A1; DE20321413U1; FR2839402B1; EP1529351A1; AU2003268134A1

Abstract

The invention provides differentiation of transmission of two types of dataflow on a common electrical distribution network (1). In particular, the invention provides modulation of useful data signals at high frequencies and modulation of communication management signals at low frequencies. Thus is obtained a high transmission speed for the useful data and a reliable and tolerant communication channel for communication management data. The high frequencies useful data signals are higher than 400KHz and the low frequencies management data signals are lower than 150KHz.

Description

COMMUNICATION NETWORK ON ELECTRICITY TRANSPORT LINE

The invention relates to carrier current telecommunications, for which the electrical network is used as a transmission medium.

It is known to use telecommunication by carrier currents in particular for making readings of electric meters. Several methods of transmission by carrier currents are currently known. According to a first process, defined for example in CENELEC standards 55-

065, carrier frequencies below 150 KHz are used. Corresponding communication protocols are defined in standards IEC 6-13-36. Such

• carrier frequencies have drawbacks for transmission. The transmission speed is limited to a speed of the order of kilobits per second. According to another method implemented, carrier frequencies greater than 1 MHz are used. These carrier frequencies make it possible to obtain transmission speeds of the order of megabits per second. Transmissions are managed using standardized protocols, such as SNMP. Signaling and transmission management information is thus transmitted using such protocols. Such carrier frequencies also have drawbacks for transmission. Their use requires a good knowledge of the structure and impedance of the network. Indeed, the propagation of the signals varies according to the geometry or the impedance of the network. The rapid evolution of the structure or impedance of the network thus generates problems of signal propagation. Poor knowledge of the distribution of the phases on the network also generates problems of signal propagation. It is thus possible to lose certain signaling and management information. There is therefore a need for a transmission method and a physical device which overcomes one or more of these drawbacks. The invention thus relates to a method of communication on an electricity distribution network, comprising the steps of transmission over the network of useful data signals modulated at frequencies higher than 400KHz, of transmission over the network of communication management signals on the distribution network, these signals being modulated at frequencies below 150 KHz. The invention also relates to a communication method in which the useful data signals are modulated at frequencies higher than 1 MHz. .

According to a variant, the communication management signals comprise data chosen from the following group: useful data management data, signaling data, data phase shift data with respect to the supply network supply voltage, communication performance data, operating state data, transmission band change command data payload, coupling control data, or coupling mode change control data.

According to a variant, communication management signals are transmitted between several communication management systems separated by transformers whose input voltage is between 3KN and 60KN.

According to another variant, the communication management signals transmitted between the communication management systems are modulated at frequencies between 3KHz and 20 KHz.

According to another variant, communication management signals are transmitted between a communication management system and a coupler of the distribution network. According to yet another variant, the communication management signals transmitted between the communication management system and a network coupler are modulated at frequencies between 9 and 150 KHz.

It can also be provided that the communication management signals transmitted between the communication management system and a network coupler are modulated at frequencies between 95 and 125 KHz.

According to a variant, the method further comprises the steps of connecting a coupler to the distribution network, of configuring the transmission of management data between the coupler and the control and monitoring system, of transmitting configuration data of the transmission of useful data, from the control and monitoring system to the coupler, of configuration of the transmission of useful data from the coupler.

According to another variant, the useful data signals are transmitted between a gateway of the distribution network and a user terminal connected to the distribution network. According to yet another variant, the gateway is also connected to a communication network outside the distribution network.

According to yet another variant, another gateway is also connected to the distribution network and to another external communication network, and the method further comprises a step of switching the transmission of useful data between the gateways.

It is also expected that the management data signals are synchronous with the supply voltage of the distribution network. According to a variant, the method further comprises the steps of measuring, by several couplers, the phase differences between the management data signals and the supply voltage, sending the measured phase differences to a control and monitoring system. connected to the distribution network, determining the structure of the distribution network according to the phase differences sent by the control and monitoring system.

According to yet another variant, the method further comprises the steps of transmitting useful data signals in a first frequency range, of switching the transmission of the useful data signals to a second frequency range.

According to another variant, the method comprises the transmission of useful data signals and management data signals over the distribution network via a coupler, the transmission of useful data by radio frequencies between the coupler and a user terminal . According to yet another variant, the method comprises the steps of detecting a failure in the transmission of useful data signals, of transmission of a test management signal by a coupler, of reception of the test signal by another coupler and determining the integrity of the physical link between the couplers.

The invention also relates to a communication device on an electricity distribution network comprising an interface for connection to an electricity distribution network, first and second modems capable of communicating with an electricity distribution network by through the interface, the modulation frequencies of the first modem being less than 150KHz and the modulation frequencies of the second modem being greater than 400KHz.

According to a variant, the interface is an interface for connection to a three-phase distribution network connected to the second modem, the device also comprises a switch capable of switching the connection of the second modem to the interface. According to another variant, the switch comprises a processor, a relay controlled by the processor placed on the connection of the second modem to the interface.

According to another variant, the second modem has several modulation frequency ranges, the device also has a command capable of modifying the modulation frequency range of the second modem.

According to yet another variant, the device is a coupler, and the coupler integrates the first and second modems. It is also expected that the device further comprises a radio frequency transmitter communicating with the second modem.

Other characteristics and advantages of the invention will appear on reading the following description of embodiments of the invention, given by way of example and with reference to the appended drawings which show:

- Figure 1, an example of a distribution network structure in which the invention is implemented; Figure 2, a diagram of the structure of a single-phase physical coupler and an associated terminal; - Figure 3, a diagram of the structure of a three-phase physical coupler and an associated gateway; FIG. 4, a diagram of the structure of a single-phase coupler incorporating a high-frequency modem; FIG. 5, a diagram of a variant of a single-phase coupler according to FIG. 4. The invention proposes to differentiate the transmission of two types of data flow over the same electrical distribution network. The invention proposes in particular to modulate useful data signals at high frequencies and to modulate communication management signals at low frequencies. This provides a high transmission speed for useful data and a reliable and tolerant communication channel for communication management data. Frequencies above 400KHz will be called high frequencies, and frequencies below 150KHz will be called low frequencies later.

The invention thus provides a high-speed transmission solution provided with reliable management, tolerant of disturbances and requiring only a reduced investment in terms of communication network. We use the power cables of the electrical network, universally connected to users. In addition, this solution uses modem elements, the selling price of which drops regularly.

Hereinafter, useful data will be used to designate data which must actually be transmitted to an end user or to his terminal. It can thus be IP packets, digital telephone communications or video surveillance flows.

FIG. 1 represents an example of a distribution network structure in which the invention is implemented. The legend at the bottom left of figure 1 makes it possible to distinguish the elements of network 1 of figure 1: element 10 corresponds to a gateway, element 20 corresponds to a user station, element 40 corresponds to a coupler three-phase and element 50 corresponds to a single-phase coupler. In this example, a high frequency element - user terminal or gateway-, is not integrated into its respective low frequency coupler. A description of integrated elements is given later.

FIG. 1 represents a distribution sub-network 1 forming a tree structure of a larger distribution network. The sub-network 1 comprises at the root of its tree structure a network head gateway 11. This head network gateway 11 is connected to a three-phase line, medium or low voltage of the distribution network. The head end gateway 11 also has a link 3 with a communication network outside the tree structure. It is thus possible in particular to provide for a connection of the head end gateway to the internet by any suitable support and protocol: a telephone link, by ADSL, by video distribution cable, by a local radio loop, by a municipal optical fiber, etc. The gateway 11 thus serves as a starting point for transmitting useful data signals in the tree structure of the electricity distribution network, with high frequency modulation. The gateway 11 can thus serve as a repeater by currents carrying the data obtained by the external communication network.

The network head gateway 11 is connected to the distribution sub-network 1 by a three-phase coupler 41. The distribution sub-network 1 also has other gateways 12, 13, 14 and 15, the function of which will be described later, connected via respective three-phase couplers 42 to 48. The gateways are preferably connected to the distribution sub-network 1 via three-phase couplers, so that they can propagate the useful data signals to all the terminals users 21 to 34 connected to one of the phases of the distribution sub-network 1. The user terminals 21 to 34 are connected to the distribution sub-network 1 by means of respective single-phase couplers 51 to 64. The user terminals are the recipients of the useful data sent on the distribution sub-network 1. The distribution sub-network 1 also includes a monitoring and monitoring system. control 2.

In the example, it is sought to transmit useful data at high speed by carrier current to the user terminals 21 to 34 from the gateway 11 connected to the internet. It is also sought to transmit communication management data by carrier current, between the control and monitoring system 2 and the coupling units.

We will now describe, with reference to FIGS. 2 and 3, an embodiment of communication elements on the distribution sub-network 1. According to this embodiment, the couplers are distinct from the associated communication element, gateway or user terminal, to be connected to the distribution sub-network 1. FIG. 2 represents a single-phase coupler 50 and an element 200 of a user terminal 20. The element 200 can take any suitable form. It can be a high-frequency modem card to be integrated into a computer or an element integrated into a user terminal 20. This coupler has an interface for connection to the distribution sub-network 1. The coupler is connected in the example one phase and neutral. A power supply 71 is connected to this interface. The power supply 71 draws current from the distribution sub-network 1 and transforms the voltage of the distribution sub-network 1 into an adequate voltage for other components of the coupler 50. A switching power supply is preferably used in order to limit the volume of the coupler. The power supply also preferably has an input inductor for damping the first harmonics of the electricity distribution frequency - for example the first four harmonics -. The input inductance can also dampen, if necessary, the pilot frequencies of the switching power supply, that is to say the frequencies between approximately 10 and 10 Hz. The power supply 71 thus supplies in the example a processor 73, a modem 72 adapted to the low frequency ranges of the transmission management signals, a processor 77 of the element 200 and a high frequency modem 76 of the element 200. The modem 76 and processor 77 can be supplied via a serial interface connecting the coupler 50 and the element 200. This interface can also be used to supply the modem 76 with useful data signals coming from the distribution sub-network 1. It is of course possible to use any other type of interface, such as a USB interface or a parallel interface.

The coupler preferably comprises a relay 74 placed on the link between the high frequency modem 76 of the element 200 and the interface with the distribution sub-network 1. This relay is controlled by the processor 73. The processor 73 can thus order relay 74 in particular to decouple the high-frequency modem from the distribution sub-network 1 in the event of a failure.

There is also preferably a transformer 78 between the modem 72 and the interface with the distribution sub-network 1. A transformer 78 is then used which is suitable for transmitting the low frequencies to the modem 72. This can thus protect the modem 72 from possible overvoltages in the distribution sub-network 1.

Similarly, the modem can be protected from possible overvoltages by placing a transformer 75 on the link between the high-frequency modem 76 of the element 200 and the interface with the distribution sub-network 1. A transformer is then used 75 suitable for transmitting the frequency ranges used by the modem 76. The modem 76 uses high frequency modulation-modulation frequencies greater than 400KHz, preferably greater than 1MHz, ranges of high frequencies being detailed later - for the transmission and reception of useful data signals.

The processors 73 and 77 can communicate via the interface connecting the coupler 50 and the element 200. The processors 73 and 77 can thus exchange management data or commands as will be described later. The processors 73 and 77 respectively control the modems 72 and 76. The processors process the data received on their respective modem. The processors also manage the broadcasts of their respective modem. The processor 73 processes the communication management data sent on the distribution sub-network 1. The processor 77 manages the useful data sent on the distribution sub-network 1.

According to a variant, the modems of the single-phase coupler 50 and of the element 200 are synchronous with the phase of the mains voltage. We can thus deduce the phase difference between a single-phase coupler and a reference phase of the distribution sub-network 1. The phase difference can be used to allow the control and monitoring system 2 to retrieve information concerning the structure of the distribution sub-network 1, as will be detailed later.

FIG. 3 represents a three-phase coupler 40 and an element 100 of a gateway 10. The element 100 can be identical to that described with reference to FIG. 2. The coupler 40 has an interface for connection to the distribution sub-network 1 preferably planned to sample the three phases on the network. A power supply 81 similar to that described with reference to FIG. 2 can be used to supply a processor 83, a modem 82 adapted to the frequency ranges of the transmission management signals, a processor 87 of the element 100 and a high modem. frequencies 86 of the element 100. The supply of the modem 86 and of the processor 87 can be carried out as described with reference to FIG. 2. The coupling of the modem to the network is carried out between the neutral and a network of star capacities towards the three phases. The element 100 of the gateway 10 can thus communicate with all the couplers connected on the three phases of the network. One could also consider using a single-phase coupler with an element 100 instead of a three-phase coupler. This is in particular possible when all the couplers are placed on the same phase of the network or when the crosstalk coupling of the three phases is provided by the network.

The coupler 40 can also include relays 84 and 89 placed on the link between the high frequency modem 86 of the element 100 and the interface with the distribution sub-network 1. These relays 84 and 89 are controlled by the processor 83 The processor 83 can control the relays 84 and 89 as before to decouple the high frequency modem 87 from the distribution sub-network 1 during a failure. In addition, relays 84 and 89 are particularly advantageous when uses a connection interface to the three phases of the distribution sub-network 1. The processor 83 can then also modify the coupling of the modem 85 to the distribution sub-network 1. The relays can thus impose a coupling between a phase and the neutral - common mode - or between two determined phases - differential mode -. One can in particular provide that the data transmitted at high frequencies by the coupler are transmitted between phases to take account of the local impedance - common mode -. It is thus possible to limit the dispersion of the communication energy, generally dissipated by electromagnetic radiation. It is also possible to provide for the high frequency data to be taken between a phase and the neutral, which represents the most frequent case in the distribution sub-network 1 of individuals. Relays controlled in a similar manner can be provided, suitable for modifying the coupling of the low-frequency modem 82 to the distribution sub-network 1.

It is of course possible to adapt the different variants of the single-phase coupler 50 to the three-phase coupler 40.

Furthermore, although couplers dissociated from their respective element have hitherto been described, it is also possible to envisage couplers integrating a high frequency modem and a low frequency modem. FIG. 4 represents an embodiment of a single-phase coupler of this type. The single-phase coupler 500 has a power supply 91, a low-frequency modem 92; a processor 93, a relay 94 and transformers 95 and 98 with structures generally similar to those of the coupler described with reference to FIG. 2. A high frequency modem 97 is here integrated in the coupler. It is supplied by the power supply 91 and coupled to the distribution sub-network 1 - or protected from the distribution sub-network 1- via the transformer 95. The high-frequency modem 97 communicates by signals modulated at high frequencies by l intermediary of the interface for connection to the distribution sub-network 1. The high-frequency modem 97 is also connected to a transmission interface to a user terminal. We can of course provide that the modem 97 integrates its own processor. The communication interface with the user terminal makes it possible to communicate useful data between the module and the user terminal. It is also possible to provide for communicating the useful data to the user terminal by means of the processor connected to the communication interface. In general, provision can be made for modems 93 and 97 to be integrated on the same card. It is also possible to integrate other components such as the power supply 91, the processor 93, the transformers 95 and 98 or the relay 94 on such a card. One can also consider using a card adapted to be mounted in a computer, and provided with a processor and high and low frequency modems. We could then consider using the computer's power supply to recover useful data and communication signals.

The structure of the control and monitoring system 2 may include a coupler of any of the types described above. The control and monitoring system 2 however preferably has a low frequency modem connected to the three phases when other three-phase couplers are used on the distribution sub-network 1. When the control and monitoring system 2 also includes a modem high frequencies, it can advantageously integrate the functions of the network head gateway. The control and monitoring system 2 then includes a link interface with an external communication network.

FIG. 5 schematically represents an example of a coupler 500 corresponding to the embodiment shown with reference to FIG. 4. The coupler 500 has an adequate plug 104 for connecting to a standard household electrical outlet. The plug 104 is connected to a suitable electrical supply, not shown. Modems 92 and 97 are connected to the plug so as to communicate on the distribution sub-network 1, as described above. The processor 93 also manages the modems as described above. The processor 93 or the high frequency modem 97 are connected to a communication interface with a user terminal, so they can be connected to a suitable communication interface 103, such as a USB or RJ 45 interface. This interface is used to connect by cable the coupler 500 to a suitable user terminal. This interface thus allows the communication of useful data between the user terminal and the coupler 500. Such a coupler thus easily plugs into any standard outlet of a user's electrical network and makes it possible to supply useful data to the user terminal.

One can also plan to use a radio frequency interface 102 with the user terminal. In particular, it is possible to communicate via the antenna 101, according to the 802.11 a, b or g standards, with a user terminal provided with a radiofrequency interface. Such an interface eliminates the cabling for the transmission of useful data.

The three-phase, single-phase couplers, and the control and monitoring system 2 each include a suitable low-frequency modem - modulation frequencies below 150KHz. The couplers of the terminals, gateways or other elements are thus capable of communicating communication management data, between themselves or with the control and monitoring system 2, using low frequency carrier currents. The use of modulation frequencies lower than 150 KHz ensures the reliability of the transmission of communication management data. Details of the modulation frequencies of the management signals will be given later.

The monitoring and control system 2 is used to manage the transmission of the signals containing the useful data from a gateway to a destination user terminal. The control and monitoring system 2 of the example thus serves to manage the operation of the couplers associated with the gateways and the terminals. The control and monitoring system 2 of the example communicates in particular with the couplers to order them to intervene on the communications of useful data. It is possible to provide a master-slave type management of the couplers of the distribution sub-network 1 by the control and monitoring system 2. The control and monitoring system 2 can in particular use the address of a coupler of the sub- distribution network 1 to interrogate it. The coupler then responds to requests by also using management and control signals modulated at low frequencies. Management and control signals are exchanged between the control and monitoring system 2 and the couplers, in particular when a coupler is put into service.

The commissioning of a coupler can take place either when the transmission is put into service on the distribution sub-network 1, or when a new coupler is connected to an existing distribution sub-network 1. The commissioning of a coupler comprises a step of configuring its low frequency link and optionally a step of configuring the high frequency link of the element connected to the distribution sub-network 1 via the coupler.

The step of configuring the low frequency link includes for example the use of the control and monitoring system 2. During the commissioning of the transmission on the distribution sub-network 1 or at regular intervals during operation, the control and monitoring system 2 interrogates the various couplers of the distribution sub-network 1 to identify them. When the distribution sub-network 1 is put into service for the first time, each coupler responds by supplying its initialization address. Provision can therefore be made for the couplers to be provided with an initialization address at the factory. This address can be assigned randomly and for example be coded on 16 bits. One could also consider assigning an initialization address ff to the couplers. When a new coupler is connected to subnet 1, the new coupler responds by providing its initialization address, while the other couplers respond by providing their final address. It is conceivable that the control and monitoring system 2 then sends a logical address to the newly connected couplers - for example a MAC address -. We then plan to store this address logic in the coupler. This address can for example be written in a non-volatile memory of EEPROM type inside the coupler. The stored address is now the address of the module used on the distribution sub-network 1.

The response of a coupler may further include information, such as its technical characteristics. The control and monitoring system 2 can then process the responses from the couplers. Depending on the responses processed, the control and monitoring system 2 can send configuration data of a module using its address, initialization or final. The purpose of this configuration data may in particular be to configure a coupler for a remote control application.

It is possible to provide for the couplers to measure the phase shift of the management data signal with respect to the mains voltage of the distribution sub-network 1. This measurement can be provided to the control and monitoring system 2 so that it determines the structure of the distribution sub-network 1. The control and monitoring system 2 determines a fictitious distance which separates it from the coupler, this distance being proportional to the measured phase difference. The control and monitoring system 2 can then establish routing plans of the useful data signals on the distribution sub-network 1. The control and monitoring system 2 can then control the repetition of the useful data by a coupler on a another frequency band according to the structure of the distribution sub-network 1 which it has determined. This variant of the method allows a better adaptation to the physical structure of the distribution sub-network 1. By performing the test step of this variant, there is also a better adaptation to the variations of structures of the distribution sub-network 1 The control and monitoring system 2 can also determine the structure of the distribution sub-network 1 by transmitting management data signals according to the principle of credits. The use of transmission credits is described in particular in standards NF EN 61 334-4-X. A step of studying the distribution sub-network 1 is carried out by emitting a signal containing credits. The credit is a number representative of the number of couplers crossed on the distribution sub-network 1 to reach a given coupler. Each time a coupler is crossed, the signal credit is decremented by this coupler. When one of the destination couplers receives a signal with zero credit, this coupler sends a response to the control and monitoring system 2. The response is notably defined at the protocol level to indicate that the coupler is placed at a determined distance on the distribution sub-network 1. It can also be provided that a coupler receiving a discovery signal with a credit of a value greater than or equal to 1 returns a list of couplers not yet declared to the control and monitoring system. surveillance 2 and of which he received responses with zero credit. By incrementing the value of the credit initially issued by the control and monitoring system 2, it is possible to reconstruct the network structure in terms of numbers of coupler crossings. This stage of studying the network can also allow the control and monitoring system 2 to decide on the routing of the useful data or to modify the frequency band for modulation of the useful data.

The control and monitoring system 2 preferably stores all the information and parameters of the couplers of the distribution sub-network 1. The control and monitoring system 2 also stores, if necessary, an image of the structure of the distribution sub-network 1.

Once the low frequency link of a coupler has been configured, this low frequency link can also be used to configure the high frequency link, that is to say the link used to transmit the useful data. A coupler processes the management data supplied by the control and monitoring system 2, then initializes the high frequency element associated with it as a function of this management data, via the serial link in the example. The coupler can in particular provide the following commands and data to the element fitted with the high-frequency modem: specification of the frequency band used, mask of carrier frequencies, control of transmission-reception gains, MAC address ... The coupler can thus either relay instructions from the control and monitoring system 2, or supply its own instructions to its corresponding element.

Once the low frequency link between the control and monitoring system 2 and a physical coupler is configured, the control and monitoring system 2 can perform the following functions via the low frequency link: the control system and monitoring 2 can interpret the structure of the distribution sub-network 1, interpret the distribution of equipment over the different phases, modify the coupling mode of the three-phase couplers or even provide elements for diagnosis. In the case of a three-phase coupler, it can thus be provided that the control and monitoring system 2 requires a modification of the physical coupling of the coupler on the distribution sub-network 1. The control and monitoring system 2 can for example impose a coupling between a determined phase and the neutral, or between two determined phases, in order to achieve a balancing of the phases of the distribution sub-network 1.

Once the high-frequency link between a gateway and a terminal is configured, these elements can exchange useful data signals on the distribution sub-network 1. Following the configuration of the high-frequency link, the control and monitoring system surveillance 2 can also provide different data or intervention requests on a high frequency link to a coupler. Among these requests or management data, we can in particular consider: the decoupling of a high-frequency element during a failure, the modification of the configuration of a high-frequency modem - notably the allocated band -, the modification of the transmission mask , modification of the physical address of the high frequency element or transmission-reception gains.

The use of distinct frequency domains for the useful data signals and the communication management signals also makes it possible to carry out a step of testing the distribution sub-network 1. Thus, in particular in the event of detection of data transmission failures useful between two couplers on the distribution sub-network 1, it is possible to send a test signal at low frequencies on the distribution sub-network 1.

If the test signal passes correctly between the couplers, it is determined that it is a simple transmission problem on the high frequency link. The control and monitoring system 2 can then command a switching of the frequency band of transmission of useful data by these couplers or alternatively a switching of the phases on which the useful data are transmitted. The switching rules between the frequency bands can be programmed in the control and monitoring system 2 according to a known behavior of the distribution sub-network 1. If the test signal does not pass correctly between the couplers, we can determine that the physical link between the couplers is disturbed. The use of such a test method therefore makes it possible to diagnose and repair the transmission problems on the distribution sub-network 1.

We will now detail the exchanges of useful data in the distribution sub-network 1 of FIG. 1. The gateway 11 provides useful data to the three-phase coupler 41, for the transmission of this data to a user terminal 26. The three-phase coupler 41 emits a high frequency modulated signal generated by the high frequency modem of the gateway 11. The signal generated by the gateway 11 contains the useful data supplied. This useful data can thus be transmitted at high speed on the distribution sub-network 1. The useful data signals pass by high frequency carrier currents on the distribution sub-network 1 to a single-phase coupler 56. These signals useful data is supplied to the high-frequency modem of the user terminal 26. The transmission of the useful data on the distribution sub-network 1 is of course similar from the user terminal to the gateway 11.

According to a variant, repetition gateways 12 to 14 are used. These gateways make it possible to regenerate the useful data signals and possibly the communication management signals in the subnetwork 1. The gateways 12 to 14 relay the signals to the user terminals 21 to 34. The repetition gateways 12 to 14 can also adapt the useful data signals coming from the gateway 11. The adaptation of the useful data signals can for example consist in transmitting the signals of useful data by modulating them in a frequency range different from their original modulation frequency range. It is thus possible to provide that the gateway 12 receives useful data signals coming from the gateway 11 with a modulation in the range from 1 to 10 MHz and re-emits these signals on the subnetwork with a modulation in the range from 10 to 20 MHz . It can also be provided that the gateways are used to relay the useful data or the management data at the transformer levels. One can for example provide that the gateways 12 and 13 are connected to couplers 42, 43 and 44, 45 respectively. The couplers 42, 43 and 44, 45 are then placed on either side of a medium voltage / low voltage transformer. We can thus foresee that the gateways cause data to pass through transformers whose input voltage is between 3KN and 60KN. The streams of useful data or of management data then pass through the gateways 12 or 13, which retransmit in a suitable frequency band this data on the part of the distribution sub-network 1 recipient of the data. The repeater gateways 12 and 13 are typically placed on the feeder feeders of the distribution sub-network 1 in order to communicate with as many user terminals as possible.

In the example of figure 1, we also use a secondary gateway

15 provided with a link 3 with a communication network outside the tree of the distribution sub-network 1. The outside communication network connected to the link 4 may be the same as the outside communication network connected to the link 3 In this case, the gateway 15 can be used as a backup gateway in the event of failure of the transmission of useful data by the gateway 11. Such redundancy of communication link with the outside can also make it possible to increase the bandwidth of communication of distribution sub-network 1 with the outside. Switching from one gateway to another can be controlled by the control and monitoring system 2 when the latter detects a communication failure from a gateway.

However, preferably external communication links 3 and 4 of different types are used. It is thus possible to provide a link 3 by cable and a link 4 by ADSL. This differentiation of the links of the distribution sub-network 1 with the outside makes it possible to switch between the gateways 11 and 15 for communication with the outside. The switchover decision may for example take into account the instantaneous speed of transmission on the links, the cost of connection on the links or even the quality of transmission on the links. In the event of a link failure, the probability of operation of the other link is also higher when the type of link is differentiated. Failover commands can be issued to a gateway either through the external communication network, or through the distribution subnet 1 using an adequate protocol.

The use of several gateways in the distribution sub-network 1 also makes it possible to use different frequency bands for different useful data flows. It can be provided that a gateway manages the routing of a specific flow on one or more frequency bands which are allocated to it on the distribution sub-network 1. It is for example possible to plan to use a frequency band for transmission internet data, and to use another frequency band for the transmission of intranet data on the distribution sub-network 1. This differentiation of flows makes it possible to limit the number of firewalls - also called firewalls in English - used. For example, we will only equip gateways dedicated to internet data transmission with firewalls. Significant savings can therefore be made in communication equipment on the distribution sub-network 1.

In the example of FIG. 1, provision is also made for the use of a backup repetition gateway 14. Such a gateway makes a connection between two branches of the distribution sub-network 1 in order to compensate for any possible failures of a gangway placed at the head of the bypass. In the example, assuming that the gateway 13 is faulty, the corresponding bypass - bypass of the couplers 57 to 64- has the bypass of the gateway 12 - bypass of the couplers 52 to 56 - through the gateway 14 for the communication of the useful data coming from the gateway 11.

The frequency range defined by the CENELEC 55-065 standard, that is to say from 9 KHz to 150 KHz, is preferably used to modulate the communication management data. One can for example use the range between 9KHz and 125, KHz corresponding approximately to bands A and B of the CENELEC standard. The propagation of signals using this frequency range is indeed much more reliable than for higher frequency ranges. Management signals thus modulated are less sensitive to phase distribution, more tolerant of the vagaries of load on the distribution network and less sensitive to changes in network structure. Advantageously, modulation of the management signals is used with a frequency between 95 KHz and 150 KHz - approximately bands B and C CENELEC -, in order to avoid the frequency spectrum generally reserved for the electricity distributor. A modulation of the management signals is also advantageously used with a frequency between 9KHz and 125 KHz - approximately the band

B CENELEC-, to avoid the frequency spectrum reserved for home automation applications. The spectrum reserved for home automation is in France band C of the CENELEC standard.

Thus, the modulation range of the management signals between 95 KHz and 125 KHz is particularly advantageous since this range is almost free.

It is also possible in a variant to put in communication control and monitoring systems 2 connected to different distribution sub-networks 1. In the case where the different control and monitoring systems 2 are separated by medium voltage transformers, a modulation preferably used in a range going from 3 KHz to 20 KHz - below the A CENELEC band - is used to transmit information between the control and monitoring system 2. The information signals thus modulated can thus pass through the smooth transformers. It can then be provided that the control and monitoring system 2 communicates with various other elements of a communication network upstream of the distribution sub-network 1.

The frequency bands from 1 MHz to 10 MHz and from 10 to 30 MHz can be used to modulate the useful data signals. A modulation carrier frequency greater than 1 MHz is preferably used to increase the speed of transmission of the useful data. It is possible to provide for the definition of several distinct frequency bands for transmitting the useful data. It is possible to change the frequency band for modulation of useful data as a function of parameters of the distribution network. Supposing for example that three frequency bands are defined, respectively from 1 to 10 MHz, from 10 to 20 MHz and from 20 to 30 MHz. These frequency bands can be used simultaneously or be used alternately. Provision can thus be made to switch the modulation of the useful data signals to a lower frequency band when a variation in the propagation characteristics on the network is detected or as a function of the other parameters described above. Of course, the present invention is not limited to the examples and embodiments described and shown, but it is susceptible of numerous variants accessible to those skilled in the art.

Claims

Communication method on an electricity distribution network (1), comprising the steps of:

-transmission on the network of useful data signals modulated at frequencies higher than 400KHz

-transmission on the network of communication management signals on the distribution network, these signals being modulated at frequencies below 150 KHz.

- The communication method according to claim 1, characterized in that the useful data signals are modulated at frequencies greater than 1 MHz.

- The communication method of claim 1 or 2, characterized in that the communication management signals comprise data chosen from the following group: useful data management data, signaling data, signal phase shift data with respect to the supply network supply voltage, communication performance data, operating state data, transmission band change control data, useful data, coupling control data or coupling mode change control data.

- The method of one of the preceding claims, characterized in that communication management signals are transmitted between several communication management systems (2) separated by transformers whose input voltage is between 3KN and 60KN.

- The method of claim 4, characterized in that the communication management signals transmitted between the communication management systems (2) are modulated at frequencies between 3KHz and 20 KHz.

- The method of one of the preceding claims, characterized in that communication management signals are transmitted between a communication management system (2) and a coupler of the distribution network (40, 41, 50, 51). o

- The method of claim 6, characterized in that the communication management signals transmitted between the communication management system (2) and a network coupler (40, 41, 50, 51) are modulated at frequencies between 9 and 150 KHz.

- The method of claim 7, characterized in that the communication management signals transmitted between the communication management system and a network coupler are modulated at frequencies between 95 and 125 KHz.

- The method of one of claims 6 to 8, characterized in that it further comprises the steps of:

-connection of a coupler to the distribution network; -configuration of the management data transmission between the module and the control and monitoring system (2);

-transmission of configuration data for the transmission of useful data, from the control and monitoring system (2) to the coupler (51); - configuration of the transmission of useful data from the coupler.

0- The method of one of the preceding claims, characterized in that: -the useful data signals are transmitted between:

a gateway (11, 15) of the distribution network (1) and a user terminal (22) connected to the distribution network (1).

1- The method of claim 10, characterized in that the gateway (11, 15) is also connected to a communication network outside the distribution network (3, 4).

- The method of claim 11, characterized in that another gateway

(15) is also connected to the distribution network (1) and to another external communication network (4), and in that it further comprises a step of switching the transmission of useful data between the gateways (11, 15 ).

- The method of one of the preceding claims, characterized in that the management data signals are synchronous with the supply voltage of the distribution network. - The method of claim 13, characterized in that it further comprises the steps of: - measurement by several couplers of the phase differences between the management data signals and the supply voltage;

sending the measured phase differences to a control and monitoring system (2) connected to the distribution network (1); -determination of the structure of the distribution network according to the phase differences sent by the control and monitoring system (2).

- The method of one of the preceding claims, characterized in that it further comprises the steps of: -transmission of useful data signals in a first frequency range;

switching of the transmission of the useful data signals to a second frequency range.

- The method of one of the preceding claims, characterized in that it further comprises the steps of:

-transmission of useful data signals and management data signals on the distribution network via a coupler; -transmission of useful data by radio frequencies between the coupler and a user terminal.

- The method of one of the preceding claims, characterized in that it comprises the steps of: ^J

-detection of a failure in the transmission of useful data signals; emission of a test management signal by a coupler;

reception of the test signal by another coupler and determination of the integrity of the physical link between the couplers.

- Communication device (40, 50, 500) on an electricity distribution network comprising:

an interface for connection to an electricity distribution network (1); -first and second modems capable of communicating with an electricity distribution network via the interface, the modulation frequencies of the first modem (72, 82, 92) being less than 150KHz and modulation frequencies of the second modem (77, 87, 97) being greater than 400KHz.

- The device of claim 18, characterized in that:

the interface is an interface for connection to a three-phase distribution network connected to the second modem;

the device further comprises a switch (83, 84, 89) capable of switching the connection of the second modem to the interface.

- The device of claim 19, characterized in that the switch comprises: - a processor (83);

a relay (84, 89) controlled by the processor placed on the connection of the second modem to the interface.

- The device of one of claims 18 to 20, characterized in that:

the second modem has several ranges of modulation frequencies; the device also has a command capable of modifying the modulation frequency range of the second modem.

- The device of one of claims 18 to 21, characterized in that the device is a coupler (500), and in; e that the coupler integrates the first and second modems (92, 97).

- The device of claim 21, characterized in that it further comprises a radio frequency transmitter (101) communicating with the second modem.