WO2003019989A1 - A lighting circuit that uses the supply current in order to exchange lighting lamp control messages - Google Patents

Abstract

The invention relates to a lighting circuit comprising a high-voltage distribution line (12), to which a plurality of low-voltage networks (16, 18, 20) are connected by means of low-frequency transformers (20, 22, 24). Each of said networks consists of a low-voltage distribution line (42), to which lighting lamps (44, 46, 48) are connected by means of lamp control modules (50, 52, 54). Transmission/reception means (34, 36) are used to exchange messages with the lamp control modules using the low-frequency supply current that is flowing through the lines as carrier current. A coupling unit (28, 30 or 32) is connected between the input/output terminals of each of the low-frequency transformers. Said coupling unit comprises voltage transformation means, which can transmit the control messages with minimum attenuation, and means for blocking the low-frequency supply current on either side of the coupling unit.

Description

 Lighting network using the supply current for the exchange of control messages for lighting lamps

Technical area

The present invention relates to lighting networks in which each lamp is controlled by a lamp control module and relates more particularly to an improved lighting network in which the supply current of the lighting lamps is used as current carrier for the exchange of control messages between a central station and each control module.

State of the art

Low voltage lighting networks, that is to say networks in which the supply current for lighting lamps is the 230 V mains current, are currently increasingly using the supply current as carrier current for the remote control. and lamp control.

The carrier current remote control systems can be systems for home networks where the communication of lamp control messages is limited to a private network located downstream of the local meter. It is the field of home automation where the network loads are essentially resistive or only slightly inductive as in the case of heating, lighting or small motors. In the case of remote control systems for public networks, the communication of lamp control messages must take place over long distances, as is the case with public lighting in cities where the load is complex and consists essentially of discharge lamps and their supply device (plates). It is also the field of road and motorway lighting if it can be distributed at low voltage. Low voltage public lighting networks of this type, where each lighting lamp is connected to a low voltage distribution line by means of a control module, find their limit when the network is too large. The voltage drops generated in the distribution line then become too great. The section of the cable used necessary to obtain an acceptable voltage drop quickly becomes prohibitive as soon as the length of the distribution line exceeds a few km. To overcome the above problem, it is therefore necessary to reduce the voltage drops and the sections of the cables used. To do this, a higher voltage is used, that is to say greater than 1000 V, for example 3200 V per phase of a three-phase source or 5500 V between phases. This supply can be obtained either by raising the low voltage to a level known as HT _T (high intermediate voltage), or by lowering the voltage obtained from a HT _A delivery station (for example 20 kv). The transport is then done over long distances by a cable of reduced section. The voltage is then re-transformed locally to supply a LV sub-network of a few hundred meters where the lighting lamps or candelabras are installed. This mode of transport allows economical lighting of entire sections of motorway, parking areas or any network infrastructure between 1 and 100 km.

Unfortunately, these HTT networks cannot function properly with regard to the transmission of control messages transmitted to the control modules associated with each lamp. Indeed, the transformers used to connect each LV sub-network to the HV _T distribution line have an impedance much too high for the frequency of the signals composing the control messages according to the legislation in force which is included in the band from 3 to 148 kHz (standard EN 50065-1). The frequency chosen is most of the time close to the upper limit, for example 130 KHz, so as to use a large bandwidth in the transmission of these messages. In addition, the HV _T network consisting of a screened and armored cable associated with the transformer loads has a characteristic impedance very different from that of a LV network. The transmission components included in the lamp control modules designed for low voltage are then completely unsuitable for HTT.

Statement of the invention

This is why the object of the invention is to design a public lighting network using the HT _T supply to supply LV subnets, in which the lamp control messages can be transmitted with minimal attenuation to each. LV subnets.

Another object of the invention is to design a lighting network of this type in which there is impedance matching between the HT _T distribution line and the lamp control modules in each of the LV networks.

The object of the invention is therefore a lighting network comprising a high voltage and low frequency power supply connected to a high voltage distribution line, a plurality of low voltage networks each connected to the high distribution line. voltage by means of a low frequency transformer each of the low voltage networks consisting of a low voltage distribution line to which lighting lamps are connected by means of lamp control modules, and emission means / reception to send messages to the lamp control modules and receive messages from them via the high and low voltage distribution lines using the low frequency supply current flowing in the lines as carrier current. A coupling module is connected between the input / output terminals of each of the low frequency transformers, this coupling module comprising voltage transformation means suitable for transmitting the messages with minimum attenuation and blocking means for blocking the current low frequency power supply on both sides of the coupling module.

Brief description of the figures

The objects, objects and characteristics of the invention will appear more clearly on reading the following description made with reference to the drawings in which:

FIG. 1 is a block diagram representing a lighting network according to the invention,

- Figure 2 shows schematically the coupling module according to the invention in the case of a power supply

HTi single phase,

- Figure 3 schematically shows a first embodiment of the coupling module according to the invention in the case of a three-phase HV _T supply, - Figure 4 schematically shows a second embodiment of the coupling module according to the invention in the case of a three-phase HT _T supply,

FIG. 5 schematically represents a first alternative embodiment of the coupling module according to the invention, and - Figure 6 schematically shows the variant illustrated in Figure 5 further comprising bi-directional amplification means.

Detailed description of the invention

Referring to Figure 1, a lighting network according to the invention comprises a supply voltage source V which can be a low voltage LV (230 V) or a high voltage HT _A (20 KV). In both cases, a transformer 10 makes it possible to obtain a voltage HT _T of at least 1000 V, for example 3200 or 5000 V. This voltage is supplied to a high voltage distribution line 12 via one or more several sectioning and measuring members 14. To the high voltage distribution line 12 which can extend over long distances are connected low voltage networks 16, 18 or 20 by means of low frequency transformers, respectively transformers 22 , 24, and 26. According to the invention, a coupling module is connected between the input and output terminals of each of the low frequency transformers. Thus, the coupling module 28 is connected between the terminals of the transformer 22, the coupling module 30 is connected between the terminals of the transformer 24 and the coupling module 32 is connected between the terminals of the transformer 26. A Note that the control and the remote control of LV networks are provided by a central station 34 through a control unit 36 connected to the high voltage distribution line 12 by a low frequency transformer 38 also comprising a coupling module between its input and output terminals.

Each of the LV networks such as the network 16 includes a low voltage distribution line 42 to which are connected lighting lamps such as lamps 44, 46, and 48, respectively through lamp control modules 50, 52, and 54 intended to receive messages from central station 34 and to transmit messages to said central station. These messages are transmitted at frequencies between 3 and 148 KHz according to the standards in force, but it is preferable to use a high frequency, for example 130 KHz so as to transmit these messages at the highest possible speed. The coupling modules 28, 30, 32 or 40 can be different while having common characteristics depending on whether the input supply of the coupling module is single-phase or three-phase, and in the latter case, depending on whether it is taken between the three phases and the earth or that it is caught between two of the phases and the third phase.

When the HTi supply supplied by the high-voltage distribution line 12 is single-phase as illustrated in FIG. 2, the coupling module 60 comprises a transformer 62 whose primary winding is connected between line 12 and the earth and the winding secondary is connected to the LV network. This transformer is suitable for transforming the HT _T voltage (for example 3200 V) into LV voltage (230 V) but includes a magnetic core in the form of a torus, rods or ferrite pots (unlike the core of the low frequency transformer into magnetic sheet) so as to present a minimum attenuation at the frequency of transmission of the control messages, for example 130 KHz. As this type of transformer whose windings contain few turns (2 or 3 turns in the primary winding and a dozen in the secondary winding) it is difficult to withstand the application of a low frequency voltage (50Hz), the coupling module comprises necessarily a capacitor 64 connecting the primary winding of the transformer 62 to the high voltage distribution line 12 and a capacitor 66 connecting the output of the secondary winding to the LV network. The purpose of capacitors 64 and 66 being to block the low frequency (50 Hz), their value is preferably chosen so as to constitute at least approximately a resonant circuit in series with the inductance resulting from the winding of the transformer 62 to which it is connected in combination with the inductance of the distribution line, respectively the HV distribution line for capacity 64 and the LV distribution line for capacity 66. Thus, the value of capacity 64 can be between 1 and 10 nF, preferably 5 nF, and the value of the capacitance 66 can be between 100 nF and 1 μF, preferably 0.5 μF.

If the HT _T supply supplied by the high-voltage distribution line 12 is three-phase, the coupling module can be presented in two different ways. In a first embodiment illustrated in FIG. 3, one side of the primary winding of the transformer 62 of the coupling module 69 is connected in parallel to the three phases of the line 12 by the respective capacitors 70, 72, 74 which have the same value substantially equal to the value of capacity 64 (Figure 2), and the other side is connected to earth as before. The secondary winding is connected to the LV network by a capacitor 66 as in the case of FIG. 2.

In a second embodiment illustrated in FIG. 4, one side of the primary winding of the transformer 62 of the coupling module 79 is connected in parallel to two phases of the high voltage distribution line by the respective capacitors 80 and 82 which have the same value substantially equal to the value of capacity 64, and the other side of the transformer is connected directly to the third phase of the line. The secondary winding is connected to the LV network by a capacity 66 as in the two previous cases. Note that this arrangement has the advantage of being independent of the earth circuit.

According to a variant of the invention, illustrated by FIG. 5, the coupling module 85 can also comprise additive components. It is thus possible to add an inductance on each side to obtain a better adaptation of the impedances. Thus, the inductance 86 in series with the capacitor 64 aims to adapt the input impedance of the coupling module seen from the high voltage side to the characteristic impedance of the high voltage distribution line. Similarly, the inductance 88 aims to adapt the impedance of the coupling module seen from the low voltage side to the characteristic impedance of the low voltage distribution line. According to another variant still illustrated in FIG. 5, it is possible to add a tuning capacity in parallel to each of the windings of the transformer 62, with the aim of constituting a parallel resonant circuit with the corresponding winding for the frequency of information transmission control (for example: 130 KHz). Thus, the capacity 90 constitutes a parallel resonant circuit with the winding on the HV side while the capacity 92 constitutes a parallel resonant circuit with the winding on the LV side. According to a variant illustrated in FIG. 6, the module can be made active. coupling 91 by adding amplifiers to the variant embodiment described above, knowing that said amplifiers could be also integrated into the embodiment illustrated in FIG. 2. In addition to the passive components already described, the coupling module comprises bidirectional amplification means consisting of the amplifier 94 in the direction BT -> HT and of the amplifier 96 in the HT -> LV direction, one or other of the two amplifiers being selected by a switch 98. The two amplifiers are supplied by the power source 100. Note that, insofar as the addition of the amplifiers modifies the characteristics of the coupling module, it is preferable to add a parallel resonant circuit consisting of the capacitor 102 and the inductor 104 so as to provide a parallel resonant circuit for the frequency of transmission of the control information (130 KHz).

It should be noted that the variant embodiments of the invention which have just been described with reference to FIGS. 5 and 6 where the supply is single-phase current, could also be applied to three-phase supplies whose preferred embodiment has has been described with reference to Figures 3 and.

Claims

1. High voltage lighting network comprising a power source of a high voltage greater than 1000 volts and of low frequency, for example 50 Hz, connected to a high voltage distribution line (12), a plurality of supplied networks in low voltage (16, 18, 20) each connected to said high voltage distribution line by means of a low frequency transformer (20, 22, 24) each of said low voltage networks consisting of a low voltage distribution line (42) to which lamps are connected lighting (44, 46, 48) via lamp control modules (50, 52, 54), and transmission / reception means (34, 36) for transmitting messages at a frequency higher than 3 kHz to said lamp control modules and receive messages therefrom via said high and low voltage distribution lines using the low frequency supply current flowing in said lines as carrier current; said network being characterized in that a coupling module (28, 30 or 32) is connected between the input / output terminals of each of the low frequency transformers, said coupling module comprising a transformer (62) having minimum attenuation at the frequency of message transmission, said transformer comprising a magnetic core in the form of a torus, rods or ferrite pots and blocking capacities (64, 66) for blocking the low frequency on either side of said coupling module. The lighting network of claim 1, wherein said high voltage distribution line (12) is a / single-phase line and said blocking capacities include a blocking capacity (64) connected in series to one side of the winding of said transformer (62) connected to said high voltage distribution line and a blocking capacity (66) connected in series on one side / of the winding of said transformer connected to said low voltage distribution line (42). 3. Lighting network according to claim 2, in which said blocking capacity (64) connected on the side of the high-voltage distribution line (12) has a value between 1 and 10 nF and said blocking capacity. (66) connected on the side of the low voltage distribution line (42) has a value between 100 nF and lμF. 4. Lighting network according to claim 1 or 2, wherein said high voltage distribution line (12) 20 is a three-phase line, and said blocking capacities include three blocking capacities (70, 72, 74) connected respectively to the three phases of said high voltage distribution line and each connected to one side of the winding of said transformer 5 (62 ) connected to said high voltage distribution line and a blocking capacity (66) connected in series to one side of the winding of said transformer connected to said low voltage distribution line. 5. The lighting network as claimed in claim 1 or 2, in which said high-voltage distribution line (12) is a three-phase line, and said blocking capacities comprise two blocking capacities (80, 82). respectively connected to two of the phases of said high voltage distribution line and each connected to one side of the winding of said transformer (62) connected to said high voltage distribution line while the other side of said winding is connected directly to the third phase of said high voltage distribution line and a blocking capacity (66) connected in series to one side of the winding of said transformer connected to said low voltage distribution line. 6. Lighting network according to one of claims 1 to 5 wherein an inductor (86) is connected in series with said blocking capacity (64) connected to the side of said high voltage distribution line (12) for the purpose to adapt the input impedance of the coupling module seen from the high voltage side to the characteristic impedance of said high voltage distribution line and an inductor (88) is connected in series with said blocking capacity (66) connected from side of said low voltage distribution line (42) in order to adapt the input impedance of the coupling module seen from the low voltage side to the characteristic impedance of said low voltage electrical distribution line. 7. Lighting network according to one of claims 1 to 6, in which a tuning capacitor (90) is connected in parallel to the terminals of the winding of said transformer (62) connected to said voltage distribution line (12 ) in order to constitute a parallel resonant circuit with said winding for the frequency of transmission of the messages, and a capacitance agreement (92) is connected in parallel to the terminals of the winding of said transformer (62) connected to said low voltage electrical distribution line (42) in order to constitute a resonant circuit parallel with said winding for the transmission frequency messages . 8. Lighting network according to any one of the preceding claims, in which each coupling module further comprises bi-directional amplification means (94, 96, 98) connected in series to one side of the winding of said coil. transformer (62) connected to said low voltage electrical distribution line (42). 9. The lighting network as claimed in claim 8, in which a parallel resonant circuit (102, 104) for the frequency of transmission of messages is connected in series with said bi-directional amplification means (94, 96, 98) of the side of said low voltage electrical distribution line.