CA2206300A1 - Power line signalling system - Google Patents
Power line signalling systemInfo
- Publication number
- CA2206300A1 CA2206300A1 CA002206300A CA2206300A CA2206300A1 CA 2206300 A1 CA2206300 A1 CA 2206300A1 CA 002206300 A CA002206300 A CA 002206300A CA 2206300 A CA2206300 A CA 2206300A CA 2206300 A1 CA2206300 A1 CA 2206300A1
- Authority
- CA
- Canada
- Prior art keywords
- phase
- coupled
- network
- voltage
- signals
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
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
Abstract
A 3-phase overhead distribution network operates at intermediate voltage (e.g.
11 kV to 33 kV), between a high voltage supply network (at e.g. 110 kV or 275 kV) and a consumer mains system (at e.g. 110 V or 230 V). A signalling system uses signals at frequencies preferably in the region of 10 kHz to 100 kHz for signalling over the network, the signals being coupled inductively to and from the network. The signals are coupled to different phases at different points in the network cross-coupling between the phases ensures that signals coupled onto the system on one phase give adequate signal strength for detection at other points in the system regardless of which phase the detector is coupled to.
11 kV to 33 kV), between a high voltage supply network (at e.g. 110 kV or 275 kV) and a consumer mains system (at e.g. 110 V or 230 V). A signalling system uses signals at frequencies preferably in the region of 10 kHz to 100 kHz for signalling over the network, the signals being coupled inductively to and from the network. The signals are coupled to different phases at different points in the network cross-coupling between the phases ensures that signals coupled onto the system on one phase give adequate signal strength for detection at other points in the system regardless of which phase the detector is coupled to.
Description
CA 02206300 1997-0~-28 ~owe~ ~i~ Si~s~alli~s System The present invention rel_tes to signalling over power linea and is mainly concerned with signalling over overhead power lines of low or inte~ - ' Ate vol-tage M~ in~ di~tri h~ti ~ n - Isener~l In most major countrie~ electricity i9 supplied on a wide scale by electricity &encr~Ling and distribution companies (electricity utilities) The distribution network normally consists of a large number of low voltage networks (often termed the mains) to which domestic and amall b ~inç~s consumers are connected with the low voltage networkR being ~upplied through a higher volta~se distribu-tion network or system (often termed the grid) The low voltage (consumer) networks may for example operate at 110 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 11 kV or 33 kV We will term the former voltages (ie the voltoges u~ed for long-distance distribution) high voltages and the latter voltages (ie the voltages relatively close to the final mains voltage 2) intermediate voltages Mains ~gnAllin~ - general The use of the mains for signalling has often been proposed System~ are available for intercommllni~ation b~ cn rooms in domestic premises (typically for "baby alarms") for coupling to the telephone system and for transmission of databetween computer units Many proposals have also been made for the use of mains Rignalling for remote meter reading (primarily for electricity meters though gas and other meters can be coupled to the mains for this purpose pref-erably through electricity meters) There is in fact an international standard now for such signalling using frequencies in the general region of 3 to 150 kHz The standard is CENELEC
EN50065 1 which specifies that frequencies in the band 3 kHz - 148 5 kHz are SW~i~U~E S~EET ~P~ULE 2~) CA 02206300 1997-0~-28 available for ~ignalling on low voltage electrical inatallations. Thia bandwidth i3 divided into several smaller bands with various uae~ and permiaaions as-ociated with them; for example. the 9 kHz - 95 kHz band is reacr ve~ for electricity aup-pliera ond their licenceea.
The signalling which iq performed by the electricity suppliera iq likely to be largely concerned with metering and more generally with load ~nd ayatem con-trol. This will therefore largely operate over the low voltage portions of the main~. However as noted above the distribution network will normally include intcr-_ ate and high voltage levels all coupled through power tranaformers. It will often be deairable for metering information collected over the low voltage portions of the network to be paa-ed on over the intel I - ate and/or high vol-tage portions and for control information to be paa~ed similarly in the oppoaitedirection. This control information may include information to be paased to the conaumers connected to the low voltage level and alao signal~ for controlling the electricity distribution sy3tem itself.
Coupling to i"te~ ~e volt~ge 2_tu.r}~a Techniques are therefore re~uired for coupling signals to inte~ te voltage networks. These signala may be gencr~Led or uaed at the coupling pointa ie the qubatationq where the inte- - ~te voltage networks are coupled with either the high or the low voltage networks or may be paaaed between the intermediate voltage network and a low voltage network coupled to it.
It may be noted that aignalling frequency signola generally do not paas through power ~diatribution) tran~formers effectively. Some means of coupling PLC ~ignalq round such transformera i~ therefore nccca~ary if signalling b~t~._cn low and inte~ te voltage portion~ of a network iq to be achieved. Thi~ will normally involve signal reception and retran~mia~ion. The signals are thus coupled ~eparately with the two qideq of a tranaformer and paased around the tran~former L_L~_cn its two sides with the signala being proc~ed to remove noise. It may also be de- irable to uqe different frequency bandq on the two sides of the tran~former. (This has the advantage that any ~ignal feedthrough which does occur at power tranqformera will be irrelevant.) SUBSl'lTUTr 5~EET ~ LE 26) CA 02206300 1997-0~-28 c Moins ~ in~5 - r clc~ncc of mains volto~e le-vel J Signal trAn-lmi~aion and reception techniques are relatively ~traightforward for low voltage (mains) networks. The signal trAn~mi~ion and reception equip-ment can be connected directly to the network wiring.
An inter~ te voltage network however pre~ent4 more difficulty for both electrical and I _-h~nical reasons. Inter-..eJiate voltoge network~ require physi-cally robu~t in~ulation which i~ largely incompatible with direct connections tothe intermediate voltage. Also fairly delicate and ~ensitive electronic equipment is largely incompstible with direct connection to inte~ - ' Ate voltages <we areusing the term "intermediate" voltage of course in connection with diatribution networkc; 11 kV for example i~ exceedingly high relative to most electronic equipment).
0~_. h~d ond ~ cr~5. c,u..d ~._tu_ h~
Di~tribution networks may be overhead underground or both. The high volt~ge portion~ are normally overhead ~ince they generally cros~ long di~tanceaof fairly open country and the cost of burying them underground would be pro-hibitive. In many countrie~ the low voltage portion~ are normally underground ~ince they are in densely populated area~ where overhead wire~ would be unduly intrusive and potentially dangerous. The inte- ~,.ciiate voltage portion~ may beoverhead or underground; a~ with the low voltage portions they are generally uncl_~rground in urban and suburban area~. We are here concerned primarily with overhead inter _~i~te-voltage network~.
For main~ ~ignalling over intermediate-voltage overhead networks it i~
obviou~ly .~cce~ry to couple a ~ignal to the network at one point and to be ableto pick up the ~ignal from the network at another point. Variou~ ways of coupling signal~ onto overhead networks have been propo~ed including inductive coupling. For thi~ a transducer compriaing a magnetic core i~ placed around one of the conductors forming a transformer. The core ha~ a signal winding wound round it ~s a primary winding and the conductor itself effectively forms asingle-turn secondary winding (for transmi~ion; for reception the conductor form~ a ~ingle-turn primary and the signal windin~; form- u multi-turn ~econ-dary). We ~Ire here concerned with such inductive coupling.
SUBSTITUTF S~EET !RU~ E 26~
CA 02206300 1997-0~-28 3--phase " _ L
Distribution systems are generally 3-phase at int~ te (and high) voltages and often at low voltages as well The di-tribution 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 Large consumers are often supplied with a 3-phase supply How-ver ~mall consumers (~uch as domestic customers) are normally only provided with a sinE51e-I?h~-e supply The supply companies endeavour to arrange the connections of the (cingle-phase) consumers so that the loads or the three phases are broadly matched or b~l~nre~ In particular an overhead inter _' ~te voltage 3-phaae network can have various single-phase branche~ or spurs because the co~t of in~t~llinE~ such a spur is significantly smaller than that of installing a 3-phase spur (Single-phnse spurs are also possible in principle with underground net-works but for various reason~ are rare in practice ) A true aingle-phase spur would uae a single one of the 3 phases ~R Y and B) together with earth or neutral but for various reasons this is gener~lly undesirable So-called single-phase spurs therefore normally use 2 of the 3 phases at the inte~ cliate voltage with the transformer at the low voltage end reducing the voltage between those 2 phaaes to the normal mains voltage (eg 110 V or 230 V) With a 3-phase system and inductive coupling the signals are carried on whichever phase the injecting transducer is coupled to ~nd the det~ting trans-ducer detects signals on whichever pha~e it is coupled to This has dictated that a single phase be used for signalling with all transducers coupled to that phase ~It is convenient to describe the phase to which the transducers are coupled as the primary phase and the other two phases as the secondary phases ) Thia has required that the primary phase be identified at all points in the system where transducers are atlnche l It has alQO meant that signalling could tonly be carried out over single-phase spurs if they included the primary phase '~
SUB~TeTUTE S~ T (R~ 26~
CA 02206300 1997-0~-2X
WO 96/17~144 PCT/GB95/02813 The p ~3~nt invention According to the pre-ent invention, there i~ provided a ~ignalling ~yJtem for ~ignalling over a 3-pho-e di~tribution network, char~cterized in that the ~ignal~ ore coupled inductively to ond from the network, ond are coupled to different pho-es at different point- in the network The ~ignal frequency is preferably in the region of 10 kHz to 100 kHz The pre~ent invention re~t~ on the di-covery or r~liz~tion that the pri-mary pha~e i~ coupled to the ~econdory pha~es (at the si~5nal frequency) suffi-ciently well for the ~ignal injected onto the primary pho~e to be ~atisfoctorilydetect~hle on the ~econdary pha~e~ a3 well a~ the primary phase Of course, the 'primary phose" is now defined by reference to a particular ~ignal injecting transducer; if another injecting tran~ducer is con~idered, its primory phose maybe different Signals will normally be coupled to the sy-tem near a transformer, and thi-coupling to the secondary pha~e~ ari~e~ Iorgely capacitively at the tran~former Ao~ume that the transformer is a 3-phaYe delta tran~former ~if it i~ octuolly o otor tran~former, we con con~ider it- delta equivolent circuit) The wir ~iinga of the tranc~former present high impe~l~nce ot the 3ignol frequency, but there are effectively shunt capacitance- ocro~ the win~ g~ from the primary pho-e to each of the two secondary phooes, and the~e capacitonces couple the si~snal on the primary pha~e to the two ~econdary pha~ea (If the actual configuration i~ a delta, there is no real neutral point If the actual configuration is a ~tar, there i5 a real neutral point, which may or may not have a neutral line connected to it; in either case, the neutral point is ideally at the some voltoge as the earth but i~ not normally connected to eorth Iground) ) There i~ also effectively a capacitance between each of the three delta points of the winrlings and eorth The two secondary-to-eorth caparit~nce~ will act, in conjunction with the capacitances acroas the two primary-to-~econdary windings, ac~ ~ignal dropper~; also, the primary-to-eorth capa~it~nce will tend to shunt the ~ignal on the primory phase to eorth But although the~e effect~
reduce the secondory signal ~trength, they do not reduce it to an unocceptoble degree 5~3BS~ E ~EE~ ~RU~E 26) CA 02206300 1997-0~-2X
There is alao a capacitance across the winding b~ cn the two ~ccondary phaaea. Under balanced load conditions the two aecondary phaaes receive equal aignala ao this capacitance is irrelevant; if the conditiona are unh~l~nr ed thia capa~;tan~e will help to equalize the aignala on the two aecondary phaaea.
At a 3-phaae termination and receiving point the aignal coupling may be coupled to any of the three pha?es. If it is coupled to the primary phaae it will of courae pick up the primary phaae aignal. If it is coupled to either of the two aecondary phaaea it will pick up a aecondary phoae ~i~snal which will beamaller than the primary phaae aignal but atill of acceptable atren~;th. Similarly, at a ainE51e-phase ~pur and receivinEj point (ie one fed with Z of the intel, _ ~te voltage phaaes) the signal coupling will pick up either a primary or a aecondaryphaae signal depending on which 2 phaaea are uaed for the apur and which of thoae 2 phaaea the aignal coupling i5 coupled to. Aa with 3-phaae terminationa the net signal current into the termination is zero, ~o there may alao be an earth current.
For signalo injected at a single-phase spur one of the 2 inter _diate voltage phaaea at the spur will neceaaarily be the primary phaae for aignala injected by the tranaducer there. There is likely to be an imh~lPn~e b_ ~.__n the aecondary phaae for the apur and the r -ini~S aecondary ph~ae but at a 3-phaae termination cignal~ on the primary phaae will divide between the two aecondary phaaea so that they can be received there on either aecondary phaae (os well as on the primary phase of courae) even though the two aecondary phnae signals m~ly be of different strengtha. Similcr me~h~niam~ will alao normally ensure that signals injected on one aingle-phase ~pur will be received at other aingle-phaae apurs.
Specific e a~ of the in~ention A 3-pha~e inter, _liate voltage diatribution network including a si~;nalling ayatem and e~...boJying the invention will now be deacribed by way of example with reference to the drawing-i in which:
Fig. 1 is a general circuit diagram of the ayatem; and Fi~;. 2 is a more detailed circuit diagram of the supply tr~msformer station.
~S~TUTF C~E~ ~RULG ~6~
W O 96/17~44 PCTtGB95/02813 Referring to Fig 1 the system is fed from a tran-former ~tation 10 which iQ fed from a high voltage grid by me~n9 of a 3-pha-e tran-former driving a 3-phase inter, - ate voltage power di-tribution sy-tem having 3 pha-e- R Y and The 3 phases are fed to a 3-pha-e 9uh~l ~tion 11 at which the power i~
transformed down to low voltngc by a 3-pha-e transformer There ore al-o two single-phese spurs from the ~ystem a spur consisting of the R and Y phases feeding a substation 12 and a spur consisting of the Y and B pha~s feeding a substation 13 Obviou-ly the ~y-t-m may have further 3-pha-e ~Yt~n~ions and ain~sle-phase spurs For simplicity only the inte~ - ~te voltag~ WiT~ ng~ of the transformers are shown with the high voltage wjn~in~5~ (for tran~form~r lO) and the Iow vol-toge windings (for tran-formers 11 to 1 3~ omitted The primary of the high-voltage transformer 10 will normally b- a delta win~ling; the ~econdary of the Iow-voltage transformer 11 will normally be a ~tar winding giving 3 seporate low-voltage phases; and the secondarie- of low-voltage tran~former~ 12 and 13 will normally each be a single winding giving a sin~sle low-voltage pha~e The station 10 has a transducer 1 OT coupled to the R phase; this trans-ducer comprises a magnetic core with the R phase power line pa~sing through it (so formin1~ a single-turn WiT~ing) and with (multi-turn) drive and ~en~e windings coupled to it (indicated symbolically by a U ) The 3-pha-e substution 11 ha~ a transducer 1 ZT coupled to its B pha-e power line; the ~ingie-pha-e ~ubatation 12 ha- a tran~ducer 1 2T coupled to its Y pha~e power line; and the single-phase substation 13 has a transducer 1 3T coupled to it~ Y phase power line The driving transducer 1 OT is coupled to the R pha-e so that pha-e i~ the primary phase and the Y and B phases are the ~econdary pha--s In th- pre--nt system the receiving transducers 11 T to 1 3T may ~ach be coupled to any pha-e and in particular may be coupled to the ~condary pha~s as shown Hith-rto it has been regarded as mandatory for the receiving transduc-rs to be coupl-d to the primary phase so that the transducers at sub~tations 11 and 12 would have to be located a~ in~ie~ted at 1 lT and 12T; it wa~ not thought possible to couple a transducer to s~lh~te~ion 13 as that substation is not fed by the primary phase It will of course be understood that while tr~rc ducer 1OT acts a~ the dri-ving tran~dIleer and transduc-rs 1 lT to 13T act as receiving transduc-r- for signals being fed from the station 10 any of the transducers can act as a dri-SUB~IT~JTE S~ ULE 26) CA 02206300 1997-0~-28 ving transducer for signals from its own substation with the other tr~naduc rs actin~; as receiving transducers The R phase is by definition the primary phase for si~5nals from tran-ducer 10T but other phases may be the primary phase for ignals injected by other transducers ~ ig 2 show- the effective circuit of the ~y-tem at transformer 10 in more detail The transformer has three intel, _ iate volta~;e windings Wl to W3 in delta configuration (If the transformer is actually ~ ~tar configuration it can be converted to the equivalent configuration shown by a standard transformation ) Fach winding is at the signal f requency shunted by a shunt capacitance shown as C 1 to C3 Each delta point is also coupled to earth by an earth cap~it~r~e~
shown as C4 to C6 Considering the system in voltage terms, the tr~rl~duc~r 10T induces a vol-talSe on the R power line This voltage is coupled to earth through 3 parallel paths capacitances C1 and C6 in series caparit~nre~ 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 Hence 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 pha-e on the Y and B power lines In current term 2 a primary current IR is induc~d in the R ph~se power line two equal and somewhat smaller secondary return currents Iy and IB, of opposite phase are induced on the Y and B power lines and an earth or l!;round return current I G, also of opposite phase to the primary current is induced in the earth at the transformer 10 Obviously IR = IY + 1~ + IG. The primary current travels out along the primary phase power iine to the various substa-tions and passes to the secondary phases and earth at those substations At the signal frequencies the power lines act as transmission lines b~ cn the sub-station~ and switchin~; points where the power di-tribution sy~tem forks <into 2-phase or 3-phase branche~) It is evident that each of the two secondary phase return currents is effec-tively divided between the various substations but that each of the s lha~ions will in general receive si~Snificant portions of the two total ~econdary phase return currents In particular sub-tation 11 will receive a significant portion of the B phase return current and substations 12 and 13 will each receive sig-5llB~TiTl,~E ~E~T ~RULE 2~
nificant portions of the Y phase return current. The receivin~; transducer~
llT 12T and 13T will therefore all receive siE;nificant 5ignals from the tran~-ducer 1 OT.
At signal frequencies the windinga of the tran5form-ra at the ~ub~tation~
are each effectively ~hunted by capa~ nC~ . and ~re al50 effectively coupled to earth by earth capacitance~. _ The currents in the power lines to which the transducers are coupled find their return routea throu~Sh these capacitancea.
(The oper~tion can of course also be explained in volta~se terms.) The present invention c~n advantaE5eoualy employ the power line ~iEsnallin~;
device described in our copendinE; application entitled Power Line Si~;nallin~s Device filed simultaneously herewith.
C~JBST~TU~ E~T ~Rl~L~
EN50065 1 which specifies that frequencies in the band 3 kHz - 148 5 kHz are SW~i~U~E S~EET ~P~ULE 2~) CA 02206300 1997-0~-28 available for ~ignalling on low voltage electrical inatallations. Thia bandwidth i3 divided into several smaller bands with various uae~ and permiaaions as-ociated with them; for example. the 9 kHz - 95 kHz band is reacr ve~ for electricity aup-pliera ond their licenceea.
The signalling which iq performed by the electricity suppliera iq likely to be largely concerned with metering and more generally with load ~nd ayatem con-trol. This will therefore largely operate over the low voltage portions of the main~. However as noted above the distribution network will normally include intcr-_ ate and high voltage levels all coupled through power tranaformers. It will often be deairable for metering information collected over the low voltage portions of the network to be paa-ed on over the intel I - ate and/or high vol-tage portions and for control information to be paa~ed similarly in the oppoaitedirection. This control information may include information to be paased to the conaumers connected to the low voltage level and alao signal~ for controlling the electricity distribution sy3tem itself.
Coupling to i"te~ ~e volt~ge 2_tu.r}~a Techniques are therefore re~uired for coupling signals to inte~ te voltage networks. These signala may be gencr~Led or uaed at the coupling pointa ie the qubatationq where the inte- - ~te voltage networks are coupled with either the high or the low voltage networks or may be paaaed between the intermediate voltage network and a low voltage network coupled to it.
It may be noted that aignalling frequency signola generally do not paas through power ~diatribution) tran~formers effectively. Some means of coupling PLC ~ignalq round such transformera i~ therefore nccca~ary if signalling b~t~._cn low and inte~ te voltage portion~ of a network iq to be achieved. Thi~ will normally involve signal reception and retran~mia~ion. The signals are thus coupled ~eparately with the two qideq of a tranaformer and paased around the tran~former L_L~_cn its two sides with the signala being proc~ed to remove noise. It may also be de- irable to uqe different frequency bandq on the two sides of the tran~former. (This has the advantage that any ~ignal feedthrough which does occur at power tranqformera will be irrelevant.) SUBSl'lTUTr 5~EET ~ LE 26) CA 02206300 1997-0~-28 c Moins ~ in~5 - r clc~ncc of mains volto~e le-vel J Signal trAn-lmi~aion and reception techniques are relatively ~traightforward for low voltage (mains) networks. The signal trAn~mi~ion and reception equip-ment can be connected directly to the network wiring.
An inter~ te voltage network however pre~ent4 more difficulty for both electrical and I _-h~nical reasons. Inter-..eJiate voltoge network~ require physi-cally robu~t in~ulation which i~ largely incompatible with direct connections tothe intermediate voltage. Also fairly delicate and ~ensitive electronic equipment is largely incompstible with direct connection to inte~ - ' Ate voltages <we areusing the term "intermediate" voltage of course in connection with diatribution networkc; 11 kV for example i~ exceedingly high relative to most electronic equipment).
0~_. h~d ond ~ cr~5. c,u..d ~._tu_ h~
Di~tribution networks may be overhead underground or both. The high volt~ge portion~ are normally overhead ~ince they generally cros~ long di~tanceaof fairly open country and the cost of burying them underground would be pro-hibitive. In many countrie~ the low voltage portion~ are normally underground ~ince they are in densely populated area~ where overhead wire~ would be unduly intrusive and potentially dangerous. The inte- ~,.ciiate voltage portion~ may beoverhead or underground; a~ with the low voltage portions they are generally uncl_~rground in urban and suburban area~. We are here concerned primarily with overhead inter _~i~te-voltage network~.
For main~ ~ignalling over intermediate-voltage overhead networks it i~
obviou~ly .~cce~ry to couple a ~ignal to the network at one point and to be ableto pick up the ~ignal from the network at another point. Variou~ ways of coupling signal~ onto overhead networks have been propo~ed including inductive coupling. For thi~ a transducer compriaing a magnetic core i~ placed around one of the conductors forming a transformer. The core ha~ a signal winding wound round it ~s a primary winding and the conductor itself effectively forms asingle-turn secondary winding (for transmi~ion; for reception the conductor form~ a ~ingle-turn primary and the signal windin~; form- u multi-turn ~econ-dary). We ~Ire here concerned with such inductive coupling.
SUBSTITUTF S~EET !RU~ E 26~
CA 02206300 1997-0~-28 3--phase " _ L
Distribution systems are generally 3-phase at int~ te (and high) voltages and often at low voltages as well The di-tribution 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 Large consumers are often supplied with a 3-phase supply How-ver ~mall consumers (~uch as domestic customers) are normally only provided with a sinE51e-I?h~-e supply The supply companies endeavour to arrange the connections of the (cingle-phase) consumers so that the loads or the three phases are broadly matched or b~l~nre~ In particular an overhead inter _' ~te voltage 3-phaae network can have various single-phase branche~ or spurs because the co~t of in~t~llinE~ such a spur is significantly smaller than that of installing a 3-phase spur (Single-phnse spurs are also possible in principle with underground net-works but for various reason~ are rare in practice ) A true aingle-phase spur would uae a single one of the 3 phases ~R Y and B) together with earth or neutral but for various reasons this is gener~lly undesirable So-called single-phase spurs therefore normally use 2 of the 3 phases at the inte~ cliate voltage with the transformer at the low voltage end reducing the voltage between those 2 phaaes to the normal mains voltage (eg 110 V or 230 V) With a 3-phase system and inductive coupling the signals are carried on whichever phase the injecting transducer is coupled to ~nd the det~ting trans-ducer detects signals on whichever pha~e it is coupled to This has dictated that a single phase be used for signalling with all transducers coupled to that phase ~It is convenient to describe the phase to which the transducers are coupled as the primary phase and the other two phases as the secondary phases ) Thia has required that the primary phase be identified at all points in the system where transducers are atlnche l It has alQO meant that signalling could tonly be carried out over single-phase spurs if they included the primary phase '~
SUB~TeTUTE S~ T (R~ 26~
CA 02206300 1997-0~-2X
WO 96/17~144 PCT/GB95/02813 The p ~3~nt invention According to the pre-ent invention, there i~ provided a ~ignalling ~yJtem for ~ignalling over a 3-pho-e di~tribution network, char~cterized in that the ~ignal~ ore coupled inductively to ond from the network, ond are coupled to different pho-es at different point- in the network The ~ignal frequency is preferably in the region of 10 kHz to 100 kHz The pre~ent invention re~t~ on the di-covery or r~liz~tion that the pri-mary pha~e i~ coupled to the ~econdory pha~es (at the si~5nal frequency) suffi-ciently well for the ~ignal injected onto the primary pho~e to be ~atisfoctorilydetect~hle on the ~econdary pha~e~ a3 well a~ the primary phase Of course, the 'primary phose" is now defined by reference to a particular ~ignal injecting transducer; if another injecting tran~ducer is con~idered, its primory phose maybe different Signals will normally be coupled to the sy-tem near a transformer, and thi-coupling to the secondary pha~e~ ari~e~ Iorgely capacitively at the tran~former Ao~ume that the transformer is a 3-phaYe delta tran~former ~if it i~ octuolly o otor tran~former, we con con~ider it- delta equivolent circuit) The wir ~iinga of the tranc~former present high impe~l~nce ot the 3ignol frequency, but there are effectively shunt capacitance- ocro~ the win~ g~ from the primary pho-e to each of the two secondary phooes, and the~e capacitonces couple the si~snal on the primary pha~e to the two ~econdary pha~ea (If the actual configuration i~ a delta, there is no real neutral point If the actual configuration is a ~tar, there i5 a real neutral point, which may or may not have a neutral line connected to it; in either case, the neutral point is ideally at the some voltoge as the earth but i~ not normally connected to eorth Iground) ) There i~ also effectively a capacitance between each of the three delta points of the winrlings and eorth The two secondary-to-eorth caparit~nce~ will act, in conjunction with the capacitances acroas the two primary-to-~econdary windings, ac~ ~ignal dropper~; also, the primary-to-eorth capa~it~nce will tend to shunt the ~ignal on the primory phase to eorth But although the~e effect~
reduce the secondory signal ~trength, they do not reduce it to an unocceptoble degree 5~3BS~ E ~EE~ ~RU~E 26) CA 02206300 1997-0~-2X
There is alao a capacitance across the winding b~ cn the two ~ccondary phaaea. Under balanced load conditions the two aecondary phaaes receive equal aignala ao this capacitance is irrelevant; if the conditiona are unh~l~nr ed thia capa~;tan~e will help to equalize the aignala on the two aecondary phaaea.
At a 3-phaae termination and receiving point the aignal coupling may be coupled to any of the three pha?es. If it is coupled to the primary phaae it will of courae pick up the primary phaae aignal. If it is coupled to either of the two aecondary phaaea it will pick up a aecondary phoae ~i~snal which will beamaller than the primary phaae aignal but atill of acceptable atren~;th. Similarly, at a ainE51e-phase ~pur and receivinEj point (ie one fed with Z of the intel, _ ~te voltage phaaes) the signal coupling will pick up either a primary or a aecondaryphaae signal depending on which 2 phaaea are uaed for the apur and which of thoae 2 phaaea the aignal coupling i5 coupled to. Aa with 3-phaae terminationa the net signal current into the termination is zero, ~o there may alao be an earth current.
For signalo injected at a single-phase spur one of the 2 inter _diate voltage phaaea at the spur will neceaaarily be the primary phaae for aignala injected by the tranaducer there. There is likely to be an imh~lPn~e b_ ~.__n the aecondary phaae for the apur and the r -ini~S aecondary ph~ae but at a 3-phaae termination cignal~ on the primary phaae will divide between the two aecondary phaaea so that they can be received there on either aecondary phaae (os well as on the primary phase of courae) even though the two aecondary phnae signals m~ly be of different strengtha. Similcr me~h~niam~ will alao normally ensure that signals injected on one aingle-phase ~pur will be received at other aingle-phaae apurs.
Specific e a~ of the in~ention A 3-pha~e inter, _liate voltage diatribution network including a si~;nalling ayatem and e~...boJying the invention will now be deacribed by way of example with reference to the drawing-i in which:
Fig. 1 is a general circuit diagram of the ayatem; and Fi~;. 2 is a more detailed circuit diagram of the supply tr~msformer station.
~S~TUTF C~E~ ~RULG ~6~
W O 96/17~44 PCTtGB95/02813 Referring to Fig 1 the system is fed from a tran-former ~tation 10 which iQ fed from a high voltage grid by me~n9 of a 3-pha-e tran-former driving a 3-phase inter, - ate voltage power di-tribution sy-tem having 3 pha-e- R Y and The 3 phases are fed to a 3-pha-e 9uh~l ~tion 11 at which the power i~
transformed down to low voltngc by a 3-pha-e transformer There ore al-o two single-phese spurs from the ~ystem a spur consisting of the R and Y phases feeding a substation 12 and a spur consisting of the Y and B pha~s feeding a substation 13 Obviou-ly the ~y-t-m may have further 3-pha-e ~Yt~n~ions and ain~sle-phase spurs For simplicity only the inte~ - ~te voltag~ WiT~ ng~ of the transformers are shown with the high voltage wjn~in~5~ (for tran~form~r lO) and the Iow vol-toge windings (for tran-formers 11 to 1 3~ omitted The primary of the high-voltage transformer 10 will normally b- a delta win~ling; the ~econdary of the Iow-voltage transformer 11 will normally be a ~tar winding giving 3 seporate low-voltage phases; and the secondarie- of low-voltage tran~former~ 12 and 13 will normally each be a single winding giving a sin~sle low-voltage pha~e The station 10 has a transducer 1 OT coupled to the R phase; this trans-ducer comprises a magnetic core with the R phase power line pa~sing through it (so formin1~ a single-turn WiT~ing) and with (multi-turn) drive and ~en~e windings coupled to it (indicated symbolically by a U ) The 3-pha-e substution 11 ha~ a transducer 1 ZT coupled to its B pha-e power line; the ~ingie-pha-e ~ubatation 12 ha- a tran~ducer 1 2T coupled to its Y pha~e power line; and the single-phase substation 13 has a transducer 1 3T coupled to it~ Y phase power line The driving transducer 1 OT is coupled to the R pha-e so that pha-e i~ the primary phase and the Y and B phases are the ~econdary pha--s In th- pre--nt system the receiving transducers 11 T to 1 3T may ~ach be coupled to any pha-e and in particular may be coupled to the ~condary pha~s as shown Hith-rto it has been regarded as mandatory for the receiving transduc-rs to be coupl-d to the primary phase so that the transducers at sub~tations 11 and 12 would have to be located a~ in~ie~ted at 1 lT and 12T; it wa~ not thought possible to couple a transducer to s~lh~te~ion 13 as that substation is not fed by the primary phase It will of course be understood that while tr~rc ducer 1OT acts a~ the dri-ving tran~dIleer and transduc-rs 1 lT to 13T act as receiving transduc-r- for signals being fed from the station 10 any of the transducers can act as a dri-SUB~IT~JTE S~ ULE 26) CA 02206300 1997-0~-28 ving transducer for signals from its own substation with the other tr~naduc rs actin~; as receiving transducers The R phase is by definition the primary phase for si~5nals from tran-ducer 10T but other phases may be the primary phase for ignals injected by other transducers ~ ig 2 show- the effective circuit of the ~y-tem at transformer 10 in more detail The transformer has three intel, _ iate volta~;e windings Wl to W3 in delta configuration (If the transformer is actually ~ ~tar configuration it can be converted to the equivalent configuration shown by a standard transformation ) Fach winding is at the signal f requency shunted by a shunt capacitance shown as C 1 to C3 Each delta point is also coupled to earth by an earth cap~it~r~e~
shown as C4 to C6 Considering the system in voltage terms, the tr~rl~duc~r 10T induces a vol-talSe on the R power line This voltage is coupled to earth through 3 parallel paths capacitances C1 and C6 in series caparit~nre~ 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 Hence 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 pha-e on the Y and B power lines In current term 2 a primary current IR is induc~d in the R ph~se power line two equal and somewhat smaller secondary return currents Iy and IB, of opposite phase are induced on the Y and B power lines and an earth or l!;round return current I G, also of opposite phase to the primary current is induced in the earth at the transformer 10 Obviously IR = IY + 1~ + IG. The primary current travels out along the primary phase power iine to the various substa-tions and passes to the secondary phases and earth at those substations At the signal frequencies the power lines act as transmission lines b~ cn the sub-station~ and switchin~; points where the power di-tribution sy~tem forks <into 2-phase or 3-phase branche~) It is evident that each of the two secondary phase return currents is effec-tively divided between the various substations but that each of the s lha~ions will in general receive si~Snificant portions of the two total ~econdary phase return currents In particular sub-tation 11 will receive a significant portion of the B phase return current and substations 12 and 13 will each receive sig-5llB~TiTl,~E ~E~T ~RULE 2~
nificant portions of the Y phase return current. The receivin~; transducer~
llT 12T and 13T will therefore all receive siE;nificant 5ignals from the tran~-ducer 1 OT.
At signal frequencies the windinga of the tran5form-ra at the ~ub~tation~
are each effectively ~hunted by capa~ nC~ . and ~re al50 effectively coupled to earth by earth capacitance~. _ The currents in the power lines to which the transducers are coupled find their return routea throu~Sh these capacitancea.
(The oper~tion can of course also be explained in volta~se terms.) The present invention c~n advantaE5eoualy employ the power line ~iEsnallin~;
device described in our copendinE; application entitled Power Line Si~;nallin~s Device filed simultaneously herewith.
C~JBST~TU~ E~T ~Rl~L~
Claims (6)
1 A signalling system for signalling over a 3-phase distribution network (10-13) characterized in that the signals are coupled inductively to and from the network, and are coupled to different phases (R, Y, B) at different points in the network (10T to R, 11T to B, 12T to R, 13T to Y).
2 A signalling system according to claim 1, characterized in that the signal frequency is in the region of 10 kHz to 100 kHz.
3 A signalling system according to either previous claim, characterized in that the system operates at a voltage between 11 kV and 33 kV.
4 A signalling system according to any previous claim, characterized in that the system includes at least one branch having only a single phase.
A signalling system according to any previous claim, characterized in that the system includes at least one branch (12, 13) having only two phases.
6 Any novel and inventive feature or combination of features specifically disclosed herein within the meaning of Article 4H of the International Convention (Paris Convention).
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9424389.6 | 1994-12-01 | ||
| GB9424389A GB9424389D0 (en) | 1994-12-01 | 1994-12-01 | Power line signalling system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2206300A1 true CA2206300A1 (en) | 1996-06-06 |
Family
ID=10765351
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002206300A Abandoned CA2206300A1 (en) | 1994-12-01 | 1995-12-01 | Power line signalling system |
Country Status (13)
| Country | Link |
|---|---|
| EP (1) | EP0806094A1 (en) |
| JP (1) | JPH10510115A (en) |
| KR (1) | KR987000737A (en) |
| AU (1) | AU3988895A (en) |
| CA (1) | CA2206300A1 (en) |
| GB (1) | GB9424389D0 (en) |
| HU (1) | HUT77613A (en) |
| IL (1) | IL116202A0 (en) |
| NO (1) | NO972478L (en) |
| PL (1) | PL320753A1 (en) |
| SK (1) | SK68097A3 (en) |
| WO (1) | WO1996017444A1 (en) |
| ZA (1) | ZA9510203B (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB9616543D0 (en) * | 1996-08-06 | 1996-09-25 | Northern Telecom Ltd | Power line communications |
| GB2383724B (en) * | 2001-12-15 | 2005-03-09 | Univ Lancaster | Communications system |
| KR100429584B1 (en) * | 2002-04-12 | 2004-05-03 | 주식회사 플레넷 | Analog front-end apparatus and power line coupler for power line communication |
| US9407326B2 (en) | 2012-02-16 | 2016-08-02 | Enphase Energy, Inc. | Method and apparatus for three-phase power line communications |
| CN106953666A (en) * | 2017-03-17 | 2017-07-14 | 珠海格力电器股份有限公司 | Transmit circuit, method and the telecommunication circuit of signal |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4481501A (en) * | 1978-08-17 | 1984-11-06 | Rockwell International Corporation | Transformer arrangement for coupling a communication signal to a three-phase power line |
| US4357598A (en) * | 1981-04-09 | 1982-11-02 | Westinghouse Electric Corp. | Three-phase power distribution network communication system |
-
1994
- 1994-12-01 GB GB9424389A patent/GB9424389D0/en active Pending
-
1995
- 1995-11-30 IL IL11620295A patent/IL116202A0/en unknown
- 1995-11-30 ZA ZA9510203A patent/ZA9510203B/en unknown
- 1995-12-01 WO PCT/GB1995/002813 patent/WO1996017444A1/en not_active Application Discontinuation
- 1995-12-01 JP JP8518449A patent/JPH10510115A/en active Pending
- 1995-12-01 EP EP95938524A patent/EP0806094A1/en not_active Withdrawn
- 1995-12-01 SK SK680-97A patent/SK68097A3/en unknown
- 1995-12-01 HU HU9800210A patent/HUT77613A/en unknown
- 1995-12-01 CA CA002206300A patent/CA2206300A1/en not_active Abandoned
- 1995-12-01 PL PL95320753A patent/PL320753A1/en unknown
- 1995-12-01 AU AU39888/95A patent/AU3988895A/en not_active Abandoned
- 1995-12-01 KR KR1019970703587A patent/KR987000737A/en not_active Application Discontinuation
-
1997
- 1997-05-30 NO NO972478A patent/NO972478L/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| WO1996017444A1 (en) | 1996-06-06 |
| GB9424389D0 (en) | 1995-01-18 |
| IL116202A0 (en) | 1996-01-31 |
| KR987000737A (en) | 1998-03-30 |
| NO972478L (en) | 1997-07-29 |
| HUT77613A (en) | 1998-06-29 |
| ZA9510203B (en) | 1997-01-29 |
| SK68097A3 (en) | 1998-01-14 |
| AU3988895A (en) | 1996-06-19 |
| EP0806094A1 (en) | 1997-11-12 |
| PL320753A1 (en) | 1997-10-27 |
| JPH10510115A (en) | 1998-09-29 |
| NO972478D0 (en) | 1997-05-30 |
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