Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04B—TRANSMISSION
  • H04B3/00—Line transmission systems
  • H04B3/54—Systems for transmission via power distribution lines
  • H04B3/56—Circuits for coupling, blocking, or by-passing of signals
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
  • H02J13/00—Circuit arrangements for providing remote indication of network conditions, e.g. an instantaneous record of the open or closed condition of each circuitbreaker in the network; Circuit arrangements for providing remote control of switching means in a power distribution network, e.g. switching in and out of current consumers by using a pulse code signal carried by the network
  • H02J13/00006—Circuit arrangements for providing remote indication of network conditions, e.g. an instantaneous record of the open or closed condition of each circuitbreaker in the network; Circuit arrangements for providing remote control of switching means in a power distribution network, e.g. switching in and out of current consumers by using a pulse code signal carried by the network characterised by information or instructions transport means between the monitoring, controlling or managing units and monitored, controlled or operated power network element or electrical equipment
  • H02J13/00007—Circuit arrangements for providing remote indication of network conditions, e.g. an instantaneous record of the open or closed condition of each circuitbreaker in the network; Circuit arrangements for providing remote control of switching means in a power distribution network, e.g. switching in and out of current consumers by using a pulse code signal carried by the network characterised by information or instructions transport means between the monitoring, controlling or managing units and monitored, controlled or operated power network element or electrical equipment using the power network as support for the transmission
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
  • H02J13/00—Circuit arrangements for providing remote indication of network conditions, e.g. an instantaneous record of the open or closed condition of each circuitbreaker in the network; Circuit arrangements for providing remote control of switching means in a power distribution network, e.g. switching in and out of current consumers by using a pulse code signal carried by the network
  • H02J13/00032—Systems characterised by the controlled or operated power network elements or equipment, the power network elements or equipment not otherwise provided for
  • H02J13/00034—Systems characterised by the controlled or operated power network elements or equipment, the power network elements or equipment not otherwise provided for the elements or equipment being or involving an electric power substation
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04B—TRANSMISSION
  • H04B2203/00—Indexing scheme relating to line transmission systems
  • H04B2203/54—Aspects of powerline communications not already covered by H04B3/54 and its subgroups
  • H04B2203/5429—Applications for powerline communications
  • H04B2203/5433—Remote metering
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04B—TRANSMISSION
  • H04B2203/00—Indexing scheme relating to line transmission systems
  • H04B2203/54—Aspects of powerline communications not already covered by H04B3/54 and its subgroups
  • H04B2203/5462—Systems for power line communications
  • H04B2203/5466—Systems for power line communications using three phases conductors
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04B—TRANSMISSION
  • H04B2203/00—Indexing scheme relating to line transmission systems
  • H04B2203/54—Aspects of powerline communications not already covered by H04B3/54 and its subgroups
  • H04B2203/5462—Systems for power line communications
  • H04B2203/5483—Systems for power line communications using coupling circuits
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y04—INFORMATION OR COMMUNICATION TECHNOLOGIES HAVING AN IMPACT ON OTHER TECHNOLOGY AREAS
  • Y04S—SYSTEMS INTEGRATING TECHNOLOGIES RELATED TO POWER NETWORK OPERATION, COMMUNICATION OR INFORMATION TECHNOLOGIES FOR IMPROVING THE ELECTRICAL POWER GENERATION, TRANSMISSION, DISTRIBUTION, MANAGEMENT OR USAGE, i.e. SMART GRIDS
  • Y04S40/00—Systems for electrical power generation, transmission, distribution or end-user application management characterised by the use of communication or information technologies, or communication or information technology specific aspects supporting them
  • Y04S40/12—Systems for electrical power generation, transmission, distribution or end-user application management characterised by the use of communication or information technologies, or communication or information technology specific aspects supporting them characterised by data transport means between the monitoring, controlling or managing units and monitored, controlled or operated electrical equipment
  • Y04S40/121—Systems for electrical power generation, transmission, distribution or end-user application management characterised by the use of communication or information technologies, or communication or information technology specific aspects supporting them characterised by data transport means between the monitoring, controlling or managing units and monitored, controlled or operated electrical equipment using the power network as support for the transmission

Definitions

• the present invention relates to signalling over power lines, and is mainly concerned with signalling over overhead power lines of low or intermediate voltage.
• the distribution network normally consists of a large number of low voltage networks (often termed the mains) to which domestic and small business consumers are connected, with the low voltage networks being supplied through a higher voltage distribution network or system (often termed the grid).
• the low voltage (consumer) networks may for example operate at 1 10 V or 230 V (or 440 V 3-phase).
• the distribution network will normally operate at more than one voltage, with long-distance distribution at voltages of say 132 kV or 275 kV which are stepped down (possibly through 2 or more stages) to a voltage of say 1 1 kV or 33 kV.
• the former voltages ie the voltages used for long-distance distribution
• the latter voltages ie the voltages relatively close to the final mains voltages
• mains signalling For signalling, Systems are available for intercommunication between rooms in domestic premises (typically for "baby alarms"), for coupling to the telephone system, and for transmission of data between computer units. Many proposals have also been made for the use of mains signalling for remote meter reading (primarily for electricity meters, though gas and other meters can be coupled to the mains for this purpose, preferably through electricity meters).
• CENELEC EN50065.1 specifies that frequencies in the band 3 kHz - 148.5 kHz are available for signalling on low voltage electrical installations. This bandwidth is divided into several smaller bands with various uses and permissions associated with them; for example, the 9 kHz - 95 kHz band is reserved for electricity suppliers and their licencees.
• the signalling which is performed by the electricity suppliers is likely to be largely concerned with metering and more generally with load and system control. This will therefore largely operate over the low voltage portions of the mains.
• the distribution network will normally include intermediate and high voltage levels, all coupled through power transformers. It will often be desirable for metering information collected over the low voltage portions of the network to be passed on over the intermediate and/or high voltage portions, and for control information to be passed similarly in the opposite direction. This control information may include information to be passed to the consumers connected to the low voltage level, and also signals for controlling the electricity distribution system itself.
• signals may be generated or used at the coupling points, ie the substations where the intermediate voltage networks are coupled with either the high or the low voltage networks, or may be passed between the intermediate voltage network and a low voltage network coupled to it.
• signalling frequency signals generally do not pass through power (distribution) transformers effectively. Some means of coupling PLC signals round such transformers is therefore necessary if signalling between low and intermediate voltage portions of a network is to be achieved. This will normally involve signal reception and retransmission. The signals are thus coupled separately with the two sides of a transformer and passed around the transformer between its two sides, with the signals being processed to remove noise. It may also be desirable to use different frequency bands on the two sides of the transformer. (This has the advantage that any signal feedthrough which does occur at power transformers will be irrelevant.) Mains signalling - relevance of mains voltage level
• Signal transmission and reception techniques are relatively straightforward for low voltage (mains) networks.
• the signal transmission and reception equipment can be connected directly to the network wiring.
• An intermediate voltage network presents more difficulty, for both electrical and mechanical reasons.
• Intermediate voltage networks require physically robust insulation which is largely incompatible with direct connections to the intermediate voltage.
• fairly delicate and sensitive electronic equipment is largely incompatible with direct connection to intermediate voltages (we are using the term "intermediate" voltage, of course, in connection with distribution networks; 1 1 kV, for example, is exceedingly high relative to most electronic equipment).
• Distribution networks may be overhead, underground, or both.
• the high voltage portions are normally overhead, since they generally cross long distances of fairly open country, and the cost of burying them underground would be prohibitive.
• the low voltage portions are normally underground, since they are in densely populated areas where overhead wires would be unduly intrusive and potentially dangerous.
• the intermediate voltage portions may be overhead or underground; as with the low voltage portions, they are generally underground in urban and suburban areas. We are here concerned primarily with overhead intermediate-voltage networks.
• Distribution systems are generally 3-phase at intermediate (and high) voltages, and often at low voltages as well.
• the distribution system therefore consists generally of 3 live supply lines, and usually a neutral (earth) line as well.
• the supply lines are conventionally termed R, Y, and B (red, yellow, and blue), forming a star connection with the neutral line.
• a true single-phase spur would use a single one of the 3 phases (R, Y, and B) together with earth or neutral, but for various reasons this is generally undesirable. So-called single-phase spurs therefore normally use 2 of the 3 phases at the intermediate voltage, with the transformer at the low voltage end reducing the voltage between those 2 phases to the normal mains voltage (eg 1 10 V or 230 V).
• the signals are carried on whichever phase the injecting transducer is coupled to, and the detecting transducer detects signals on whichever phase it is coupled to.
• a signalling system for signalling over a 3-phase distribution network, characterized in that the signals are coupled inductively to and from the network, and are coupled to different phases at different points in the network.
• the signal frequency is preferably in the region of 10 kHz to 100 kHz.
• the present invention rests on the discovery or realization that the primary phase is coupled to the secondary phases (at the signal frequency) sufficiently well for the signal injected onto the primary phase to be satisfactorily detectable on the secondary phases as well as the primary phase.
• the "primary phase” is now defined by reference to a particular signal injecting transducer; if another injecting transducer is considered, its primary phase may be different.
• the two secondary-to-earth capacitances will act, in conjunction with the capacitances across the two primary-to-secondary windings, as signal droppers; also, the primary-to-earth capacitance will tend to shunt the signal on the primary phase to earth. But although these effects reduce the secondary signal strength, they do not reduce it to an unacceptable degree.
• the signal coupling may be coupled to any of the three phases. If it is coupled to the primary phase, it will of course pick up the primary phase signal. If it is coupled to either of the two secondary phases, it will pick up a secondary phase signal, which will be smaller than the primary phase signal but still of acceptable strength. Similarly, at a single-phase spur and receiving point (ie one fed with 2 of the intermediate voltage phases), the signal coupling will pick up either a primary or a secondary phase signal, depending on which 2 phases are used for the spur and which of those 2 phases the signal coupling is coupled to. As with 3-phase terminations, the net signal current into the termination is zero, so there may also be an earth current.
• one of the 2 intermediate voltage phases at the spur will necessarily be the primary phase for signals injected by the transducer there.
• Similar mechanisms will also normally ensure that signals injected on one single-phase spur will be received at other single-phase spurs.
• Fig. 1 is a general circuit diagram of the system
• Fig. 2 is a more detailed circuit diagram of the supply transformer station.
• the system is fed from a transformer station 10 which is fed from a high voltage grid by means of a 3-phase transformer driving a 3-phase intermediate voltage power distribution system having 3 phases R, Y, and B.
• the 3 phases are fed to a 3-phase substation 1 1 at which the power is transformed down to low voltage by a 3-phase transformer.
• the system may have further 3-phase extensions and single-phase spurs.
• the intermediate voltage windings of the transformers are shown, with the high voltage windings (for transformer 10) and the low voltage windings (for transformers 1 1 to 13) omitted.
• the primary of the high-voltage transformer 10 will normally be a delta winding; the secondary of the low-voltage transformer 1 1 will normally be a star winding giving 3 separate low-voltage phases; and the secondaries of low-voltage transformers 12 and 13 will normally each be a single winding giving a single low-voltage phase.
• the station 10 has a transducer 10T coupled to the R phase; this transducer comprises a magnetic core with the R phase power line passing through it (so forming a single-turn winding) and with (multi-turn) drive and sense windings coupled to it (indicated symbolically by a "U").
• the 3-phase substation 1 1 has a transducer 12T coupled to its B phase power line; the single-phase substation 12 has a transducer 12T coupled to its Y phase power line; and the single-phase substation 13 has a transducer 13T coupled to its Y phase power line.
• the driving transducer 10T is coupled to the R phase, so that phase is the primary phase and the Y and B phases are the secondary phases.
• the receiving transducers 1 1T to 13T may each be coupled to any phase, and in particular may be coupled to the secondary phases as shown. Hitherto it has been regarded as mandatory for the receiving transducers to be coupled to the primary phase, so that the transducers at substations 1 1 and 12 would have to be located as indicated at 1 1T' and 12T'; it was not thought possible to couple a transducer to substation 13, as that substation is not fed by the primary phase.
• transducer 10T acts as the driving transducer and transducers 1 1T to 13T act as receiving transducers for signals being fed from the station 10
• any of the transducers can act as a dri ving transducer for signals from its own substation, with the other transducers acting as receiving transducers.
• the R phase is by definition the primary phase for signals from transducer 10T, but other phases may be the primary phase for signals injected by other transducers.
• Fig. 2 shows the effective circuit of the system at transformer 10 in more detail.
• the transformer has three intermediate voltage windings W1 to W3 in delta configuration. (If the transformer is actually a star configuration, it can be converted to the equivalent configuration shown by a standard transformation.) Each winding is, at the signal frequency, shunted by a shunt capacitance, shown as C 1 to C3. Each delta point is also coupled to earth by an earth capacitance, shown as C4 to C6.
• the transducer 10T induces a voltage on the R power line.
• This voltage is coupled to earth through 3 parallel paths: capacitances C1 and C6 in series, capacitances C3 and C4 in series, and capacitance C5.
• the two series paths C 1-C6 and C3-C4 result in voltages being induced on the Y and B phase power lines.
• all three power lines have voltages induced on them; a primary voltage on the primary (R) phase, and two equal and somewhat smaller voltages, of opposite phase, on the Y and B power lines.
• a primary current I R is induced in the R phase power line
• two equal and somewhat smaller secondary return currents 1 Y and 1 B are induced on the Y and B power lines, and an earth or ground return current I C , also of opposite phase to the primary current, is induced in the earth at the transformer 10.
• I R I Y + I B + I G .
• the primary current travels out along the primary phase power line to the various substations and passes to the secondary phases and earth at those substations.
• the power lines act as transmission lines between the substations and switching points where the power distribution system forks (into 2phase or 3-phase branches).
• each of the two secondary phase return currents is effectively divided between the various substations, but that each of the substations will in general receive significant portions of the two total secondary phase return currents.
• substation 1 1 will receive a significant portion of the B phase return current
• substations 12 and 13 will each receive sig nificant portions of the Y phase return current.
• the windings of the transformers at the substations are each effectively shunted by capacitances, and are also effectively coupled to earth by earth capacitances.
• the currents in the power lines to which the transducers are coupled find their return routes through these capacitances. (The operation can of course also be explained in voltage terms.)
• the present invention can advantageously employ the power line signalling device described in our copending application entitled “Power Line Signalling Device”, filed simultaneously herewith.

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• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Computer Networks & Wireless Communication (AREA)
• Signal Processing (AREA)
• Cable Transmission Systems, Equalization Of Radio And Reduction Of Echo (AREA)
• Ac-Ac Conversion (AREA)

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• 1994
  • 1994-12-01 GB GB9424389A patent/GB9424389D0/en active Pending
• 1995
  • 1995-11-30 IL IL11620295A patent/IL116202A0/xx unknown
  • 1995-11-30 ZA ZA9510203A patent/ZA9510203B/xx unknown
  • 1995-12-01 WO PCT/GB1995/002813 patent/WO1996017444A1/en not_active Application Discontinuation
  • 1995-12-01 CA CA002206300A patent/CA2206300A1/en not_active Abandoned
  • 1995-12-01 KR KR1019970703587A patent/KR987000737A/ko not_active Application Discontinuation
  • 1995-12-01 PL PL95320753A patent/PL320753A1/xx unknown
  • 1995-12-01 SK SK680-97A patent/SK68097A3/sk unknown
  • 1995-12-01 JP JP8518449A patent/JPH10510115A/ja active Pending
  • 1995-12-01 AU AU39888/95A patent/AU3988895A/en not_active Abandoned
  • 1995-12-01 EP EP95938524A patent/EP0806094A1/en not_active Withdrawn
  • 1995-12-01 HU HU9800210A patent/HUT77613A/hu unknown
• 1997
  • 1997-05-30 NO NO972478A patent/NO972478L/no unknown

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