GB2379993A

GB2379993A - Electrical energy consumption and generation metering arrangement

Info

Publication number: GB2379993A
Application number: GB0218497A
Authority: GB
Inventors: Robert Rivers Loe
Original assignee: Siemens Metering Ltd
Current assignee: Siemens Metering Ltd
Priority date: 2001-08-10
Filing date: 2002-08-09
Publication date: 2003-03-26
Also published as: WO2003014748A1; GB0119544D0; GB0218497D0; WO2003014748A9

Abstract

An electrical meter arrangement 10 comprises means operable to meter an amount of electrical energy consumed 12 and an amount of electrical energy generated 14 at a premises and in which the said means is sealed in a single enclosure 13. Two meter circuits 12, 14 may be used to measure the energy consumed and generated, respectively. The meter arrangement 10 may be connected between a premises and an electricity distribution network 11. Separate data relating to energy consumption and generation may be communicated to a central control unit to calculate appropriate billing taking into account the relevant tariff charges for the said data. The data may be communicated optically, by radio or by smart card. The meter arrangement may include one or more internal switches 32, 34 operated by a control unit to reconfigure the meter connections with respect to the network and a local generator.

Description

IMPROVEMENTS IN OR RELATING TO

ELECTRICITY METERS

Field of the Invention

5 This invention relates to electricity meters. In particular, but not necessarily restricted thereto, the present invention relates to consumption and generation meters and to meters situated at premises that consume, import, generate and export electrical energy.

10 Background to the Invention

., L In some countries, such as the United Kingdom, there are a growing number of residential or small-scale generation schemes.

Many schemes benefit from governmental support. Accordingly there has been experienced an increasing amount of interest in the associated 15 aspects of metering, generation control, energy settlement and reconciliation, and charging relating to the use of the power transmission and distribution networks. This local domestic power generation is generally classed as micro-generation. The terms import and export refer to energy being drawn from the electricity distribution 20 network and energy being fed into the electricity distribution network respectively. In general, the consumption of certain utilities such as electricity varies throughout the day and night, in addition to seasonal variations.

A typical domestic installation for micro-generation would consist of a 25 normal domestic electricity feed plus a small local generator that may be used to serve a steady base load, or to reduce peak demand on the

-2 normal incoming feed. Nevertheless, in such installations there will be the possibility that, at times, the local generation may exceed the local demand resulting in energy being exported from the domestic premises. Under such circumstances it is reasonable for the domestic 5 owner to expect payment for the energy he has exported. In some existing small-scale residential generation schemes a single electricity meter arrangement that is capable of measuring in both energy directions, driving either separate export and import registers or a single reversible net register, has been used. This so-called "net meter" 10 arrangement can only be used validly under strict control because of inherent opportunities for fraud that make it increasingly inapplicable for residential use in the present day free-market electricity supply industry. Notwithstanding this, simple net metering of the difference between import and export using a single reversible meter register may IS not be acceptable to the utility company or consumer who, for a .. number of reasons, will probably not want/allow the same charges to apply for both import and export quantities of electrical energy.

As will be appreciated, the application of basic economics principles will mean that, in a simple case, the price for buying energy 20 may not be the same as the price for selling it, at any given time.

Furthermore, there may exist different wholesale market settlement and reconciliation arrangements for energy consumption compared to energy generation, for example, the consumption may be treated on the classaverage profiling method, while generation may be treated by 25 recording and processing half-hourly data. In addition, certain additional metering data may also be required to allow charging for use of the transmission and distribution systems.

2001 P1 4924GB

- 3 Object of the invention The present invention seeks to provide an improved electricity consumption, generation, import and export meter. The present invention also seeks to provide a system for the settlement and 5 reconciliation arrangements for utility consumption and an associated method. The present invention also seeks to provide flexible electricity metering equipment and system that provides improved security against attempts to defraud and/or tamper.

10 Statement of the Invention

In accordance with a first aspect of the invention, there is provided an electricity meter, including first and second meter circuits wherein such meter circuits are sealed in a single enclosure and are operable to meter an amount of electrical energy consumed at a 15 premises and to meter an amount of electrical energy generated at the premises. The present invention therefore can assist in the realization of advantages with commercial arrangements for the retailing of electrical energy and for wholesale trading, that are typically different for 20 consumption as compared to generation and/or for import as opposed to export.

This invention places the metering equipment in one common enclosure, either an enclosure housing two separate meters or a single meter with two separate measuring elements or functions. The 25 enclosure is capable of being sealed by a representative of a utility company and is configured to fit physically closely to an incoming supply cut-out of a standard domestic installation. The cut-out may 2001 P1 4924GB

- 4 comprise a fused arrangement but can also comprise a switch. Internal wiring within the enclosure connects the two meters to the incoming supply. This configuration can reduce tampering, as access to the incoming power side of the meters is not available without separating S the combined meter box from the incoming supply conductor from the cut- out or opening the enclosure. This cannot be done without breaching a seal, thus leaving evidence of tampering.

The above configuration allows access to meter readings both for consumption and generation. In accordance with a further aspect of 10 the invention, there is provided a meter operable to meter an amount of electrical energy consumed at a premises and to meter an amount of electrical energy generated at the premises in a single sealed enclosure, further comprising a data communication system whereby data relating to both energy consumption and generation for the domestic premises 15 are communicated to a central control unit for energy settlement/ À ( reconciliation andJor system usage. This provides a flexible metering approach where energy, settlement and reconciliation may be performed over half-hour or other periods of time, as desired. Thus, the present invention will be able to manage competitive electricity 20 markets in a number of ways in a much more relevant fashion than is currently the practice.

The invention also allows the provision of a communications channel thus allowing collection of metering data and settlement and reconciliation of charges. The settlement and reconciliation 25 requirements can also encourage the consumer to facilitate communication of the data to the electricity companies or other bodies so as to get repayment for exported energy. In cases where the site at 2001 P1 4924GB

- 5 which the meter is situated is a residential household with its own small-scale generator, such as micro-CHP, photo-voltaic roof, fuel cell, or a small hydro or wind unit, these differences may be very significant and may be addressed in a practical, effective, and economic manner 5 by the invention.

Such a communications channel may employ wireless, PSTN line, smart-card or any other suitable technology to enable data transfer at low cost. A unidirectional command channel may also be provided, for example, by a radio tale-switch system or ripple control system.

10 The dual meter arrangement preferably provides switches in the :, connections from the meter to both the generator and the consumer load. In accordance with a further aspect of the invention, there is provided an electrical energy supply distribution network including 15 low resistance conductors which are connected to an electrical energy .. . generation station and to domestic and/or business consumers wherein one consumer is provided with a meter operable to meter an amount of electrical energy consumed at a premises and to meter an amount of electrical energy generated at the premises in a single enclosure, 20 whereby the meter arrangement is operably arranged and sealed within the enclosure.

In accordance with a still further aspect of the invention, there is provided a method of providing electricity to an electrical energy distribution network by means of a micro-generation unit including a 25 meter operable to meter an amount of electrical energy consumed at a premises and to meter an amount of electrical energy generated at the premises in a single enclosure; whereby the meter arrangement is 2001 P 1 4924GB

- 6 operably arranged and sealed within the enclosure; whereby, under conditions of low energy consumption by the consumer, electrical energy is exported to the network via the meter.

5 Brief description of the Figures

The invention may be understood more readily, and various other aspects and features of the invention may become apparent from consideration of the following description and the Figures as shown in

the accompanying drawing sheet, wherein: 10 Figure 1 shows an overview of a first meter arrangement in c accordance with the present invention; Figure 2 shows a second embodiment of the invention; Figure 3 shows a third embodiment of the invention; Figure 4 shows a further variant of the invention; 15 Figure 5 shows an opto-port data transfer devices; .. . Figure 6 shows a meter with a smart card data transfer device; and, Figure 7 shows a meter with radio data transfer capabilities.

20 Detailed description of the invention

There will now be described, by way of example, the best mode contemplated by the inventor for carrying out the invention. In the following description, numerous specific details are set out in order to

provide a complete understanding of the present invention. It will be 25 apparent, however, to those skilled in the art, that the present invention may be put into practice with variations of this specific.

Referring now to Figure 1, there is shown a combined electrical 2001 P1 4924GB

- 7 energy consumption and generation meter 10 including two electrical kilowatt-hour meters, one for consumption 12 and one for generation 14. These meters will typically be a.c. single-phase types but may otherwise be a.c. polyphase, or d.c. types. Similarly whilst both meters 5 may be single-phase or polyphase, the generation meter will typically be of an a. c. single-phase type. This metering circuit comprises an enclosure 13 and the meters are both connected by respective connector lines 61, 62 to the same terminal 16 with respect to the distribution network 11 and a fuse, cut-out or alternative arrangerr ent 10 18 will be provided on conductor line 63. Where the consumption meter is polyphase but the generation meter is single-phase, the meter arrangement can provide alternative connection facilities to select the phase to which the generation meter is connected. The meters can be whole-current types or low-voltage current-transformer-connected 15 types when certain optional additional facilities are needed dependent .. i upon operational requirements.

The consumption meter 12 is connected by conductor lines 91, 92 to a terminal 20 via a switch 32, which connects to the customer's load 24 by conductor line 93. The consumption meter 12 includes one 20 or more registers for the energy consumed by the load 24 and these may also be controlled on a time-of-use basis. These registers may alternatively be located elsewhere. The generation meter is connected by conductor lines 94, 95 to a terminal 22 via a switch 34, which connects to the customer's own generator 26 by conductor line 96.

25 The generation meter 14 includes one or more registers for the electrical energy generated and these may also be controlled on a time-

of-use basis. These registers may alternatively be located elsewhere.

2001 P1 4924GB

- 8 A display 28 is provided to indicate electrical energy consumption/generation rates, totals and any other data.

A control circuit 30 is situated within the meter and is operably connected to a generator control unit 27, meters 12, 14 and switches 32 5 and 34 via respective control lines 86, 88, 83, 82, 84 whereby to selectively enable (i) disconnection of the local electrical energy supply from the electrical energy distribution network 11; (ii) connection of generator 26 through the generation meter 14, to load 24 and/or to supply the electrical energy distribution network 11.

10 Typically, in a micro-CHP generator arrangement, there is provided a voltage matching and synchronization circuit in the generator control unit 27. It will be appreciated that the generator can be capable of supplying electrical energy simultaneously with the electricity distribution network to the load. This control unit 30 may include 15 registers 31, 33 respectively associated with the meters 12, 14. The control unit 30 is also connected to fuse/cut-out arrangement 18. The control unit 30 can be arranged to provide an indication of electricity distribution network failure via line 81. The generator control unit 27 is also connected by control line 87 to switch 35 associated with 20 generator 26 and can control the generator output. Alternatively, the meter control unit 30 may override generator control unit 27. A power synchronization facility may then be provided by control unit 30.

Referring now to Figure 2, there is shown a further embodiment of the invention wherein there is provided a combined electrical energy 25 consumption and generation meter 110 including two a.c. electrical kilowatt-hour meters, one for consumption 12 and one for generation/consumption 114. These meters are enclosed by an 2001 P 1 4924GB

- 9 - enclosure 113; the meter 110 is connected by the same terminal 16 to the electricity distribution network 11; current conductors 61 and 162 from meter 12 and switch 34 meet at junction 116 and conductor 163 connects the junction 116 to generation meter 114. Conductor 263 5 connects the meter 114 with the input terminal 16. A fuse or alternative cut-out arrangement 18 is preferably provided. A further embodiment, similar to Figure 2, may be configured such that meter 114 a similar meter 114) is supported by meter 14 of figure 1 and meter 12 of figures 1 and 2 is absent. The total of electrical energy 10 meter 114a minus metered amounts of electrical energy of meter 14 - gives consumedJimported amount of electrical energy.

The consumption and generation meters 12, 114 can include one or more registers (not, shown) for the energy consumed by the load and these may also be controlled on a time-of-use basis. The power 15 synchronization and control circuit 30 is operably connected to the ... - meter 114 via control line 183. Meter 114 can be a unidirectional meter (import or export only) or a bi-directional meter (separate import and export registers, or one net register only).

Figure 3 shows a further combined electricity consumption and 20 generation meter 210 including three a.c. electricity kilowatt-hour meters, one for consumption 12 and two for generation 14,17. Meters 12, 14 are enclosed by an enclosure 213 and are connected to the same terminal 16 and thus connected to the distribution network 11 and a fuse or alternative cut-out arrangement 18 will be provided. A meter 25 17 is provided on current conductor 89, although this is, in fact, optional. That is to say, the meter 17 is not employed in any reconciliation matters with an electricity distribution and/or supply 2001 P 1 4924GB

- 10 company. The meter 17 may alternatively comprise part of meter enclosure 213.

In contrast to the first and second embodiments described above, there is a separate, directly connected supply from the generator 26 to 5 the load 24. Alternatively the supply may connect with load terminal 2(). Switch 36 is either controlled by generator control 27 or indirectly controlled by control unit 30.

The consumption meter 17 can also include one or more registers for the electrical energy consumed by the load and these may 10 also be controlled on a time-of-use basis. The meter 17 can be connected to display 28 by a communication line (not shown).

The control circuit 30, in this embodiment, can selectively enable (i) disconnection of the local electrical energy supply from the electricity distribution network 11; (ii) connection of generator 26 to 15 load 24; and (iii) connection of the generator 26 through the generation meter 14 to supply the electricity distribution network 11 and supply load 24 via switch 32.

In the case that electronic meters are employed to record electrical energy consumption/generation, then there will be associated 20 data stores 38, 40 to record such data as shown in Figure 4, which shows an alternative arrangement, in greater detail, of two meters and the control unit. The combined meter may incorporate an additional import/export energy calculation (net energy calculation) facility 42, driven by continuously updated energy consumption and generation 25 signals 44, 46 from the two meters 12, 14, (including any reverse energy signals). The results of the calculations are then fed to the registers and may also be used to provide a signal to the control unit 2001 P1 4924GB

30. The import/export calculation device 42 will take into account consumption/generation tariff or charging data provided by data stores 31, 33. The various energy advances may be recorded at regular intervals such as every half hour or hour, every day, every 5 week/weekend, every month, every quarter, or every year, as required.

Different measured energy quantities may be recorded under different intervals, to meet the different energy supply/generation/network requirements. The recorded data may include flags to indicate generation activity or disconnection at different times or intervals, : 10 which may be subject to different tariffs/charges. The data from the <; data stores (registers) can be made available for detailed accounting uses. Preferably a reverse register is associated with each meter whereby to assist in the determination of fraudulent activities.

The combined meter may include alternative local and remote 15 communications facilities. In a simple form, and as shown in Figure S. an optical data port 48 may be included so that data from the registers and other recorded data may be passed to an opto-port and meter parameters exchanged during visits by a meter reader acting on behalf of an electricity supply, or distribution company, using a matching 20 handheld unit SO. An alternative is shown in Figure 6 where there is provided a smart card interface 54. A smart card may be used from time to time to collect recorded data at suitable intervals, after an exchange of data the smart card may be sent to a utility company. The smart card may then be re-used.

25 Referring to Figure 7, there is shown a radio transmitter or transceiver 60 or similar facility operable so that meter data can be transferred via base station 62. The meter data may be transferred by 2001 P14924GB

- 12 radio signals to the base station. Alternatively a radio interrogation unit 64 may be carried by a meter reader who can then determine the meter reading without physically gaining access to the meters situated on the outside of houses, or otherwise. Alternative facilities for remote 5 communications may be supported by and/or incorporated in the meter, including for example, interfacing with a PSTN telephone line modem, or a mobile radio data transceiver.

Referring to Figure 8, a radio tale-switch receiver or ripple control receiver or similar 113 comprises part of the meter 13, and is 10 operable so that broadcast commands from radio tale-switch transmitter network 162 may be accepted and acted upon to control the activity of the tariff rate registers or circuit switches in the meter, if required for power system operational purposes or for energy tending purposes. 15 The terminals of the two meters on the electricity network side are arranged so as to prevent any other connections being made, for instance by arranging to mount the meter and its terminals close up against the fuse cut-out. The internal meter layout and energy measurement circuits are chosen and arranged so as to provide no 20 influence or minimal influence on meter errors between the consumption and generation circuits, for instance when one meter is at high current while the other is at low current. Furthermore, the nominal or basic and maximum current ratings of the generation meter may be lower than is usual for a consumption meter, so that accurate 25 metering is maintained at low levels of generation output.

Either or both of the consumption and generation meters may include a reverse energy register to monitor any unexpected conditions, 2001 P1 4924GB

- 13 such as might result from unauthorised connections around each meter, or between the load and generator sides of the two meters. These reverse energy registers may also indicate data on the display.

The implementation of the combined meter may be made in a 5 number of ways involving arrangements of electronic and electrical components and techniques that are already known, including an arrangement where much of the functionality is provided by a microprocessor-based circuit supported by appropriate memory, inputloutput interfaces, sensors, and any actuators, operating under the 10 control of stored programme software.

Where the meter includes the synchronization and power monitor/control facilities within control unit 30 in Figure 1 and the system is a.c., then the a.c. voltage signals from each side of the generation switch can be compared in magnitude and phase so that the 15 correct conditions are checked before the generator can be connected.

Alternatively, the generator itself may run up, regulate, and synchronise itself by reference to the voltage on line 94 or a connection from load circuit 24.

The present invention therefore can assist in the realisation of 20 advantages with commercial arrangements for the retailing of electricity (and for wholesale trading), which may be different for consumption as compared to generation and/or for import as compared to export. In a liberalized electricity market there may also be different wholesale market settlement and reconciliation arrangements for 25 energy consumption compared to energy generation, for example the consumption may be treated on the class-average profiling method, while generation may be treated by recording and processing half-hour 2001 P1 4924GB

- 14 data. The trading arrangements may permit the "customer" to register with a chosen supplier for normal energy consumption, and with a separate purchaser for energy generation, where the purchaser may wish to aggregate and trade on behalf of a large number of small S generators.

Some power generators such as micro-CHP generators will operate in an "all or nothing" basis, ie., they produce power at a particular rate or not at all. Smart generators, linked to a controller and/or a battery power storage arrangement may provide energy 10 responsive to demand.

In a distribution network, where there are a number of consumer/ generators, then issues of 'islanding' may arise. Islanding refers to instances where a locality is disconnected from a main network, for example by reason of a flood or storm damage. Continued connection 15 of each consumer generator could enable the locality to have a basic, reduced power electrical energy supply. This may be of benefit to fangs and other types of businesses where a 24 hour a day supply is required. Nevertheless the 'islanded' distribution network and associated microgeneration must all be capable of enabling such 20 continued supply. Alternatively, through legislation or otherwise, such continued supply may be prevented and, for example, upon detection of a supply network breach the power control unit 30 may activate a trip in, for example, arrangement 18, or open switches 34 and 36.

2001 P1 4924GB

Claims

- 15 CLAIMS

1. An electricity meter, including first and second meter circuits wherein such meter circuits are sealed in a single enclosure and are operable to meter an amount of electrical energy consumed at a premises and to meter an amount of electrical energy generated at the premises.

2. A meter according to claim 1, wherein the meter is operable to provide consumption data and generation data separately.

3. A meter according to claim 2, wherein there is a register operable to store data relating to the electrical energy consumed and a register to store data relating to the electrical energy generated.

4. A meter according to claims 1 to 3, wherein the import/export or net energy calculation is derived from the internal registers, taking into account the appropriate tariff/charges for each quantity.

5. A meter according to any one of claims 1 to 4, wherein each meter contains a reverse energy register.

6. A meter according to any one of claims 1 to 5, wherein the meter has a control unit, the control unit being operable to actuate one or more switches.

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7. A meter according to any one of claims 1 to 6, wherein the meter is provided with internal switches operable to enable/disable connection of the meter with respect to electrical energy from an electricity distribution network and with respect to electrical energy from a local electricity generator.

8. A meter according to any one of claims 1 to 7, wherein electrical energy can be provided directly to a customer load from the local electricity generator.

9. A meter according to any one of claims 1 to 8, wherein the electrical energy from the local electricity generator direct to the load is metered by a third meter.

10. A meter according to claim 9, wherein the third meter is a separate meter.

11. A meter according to any one of claims 1 to 10, further comprising a data communication facility whereby data relating to both energy consumption and generation or any calculated quantity for the domestic premises are communicated to a central control unit for settlement/reconciliation/ network usage charging.

12. A meter according to claim 11 wherein the meter corurnunication system employs a smart card operable to transfer the data from the meter to the central control unit.

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13. A meter according to claim 11 or 12, wherein different tariffs/charges can be applied to the generated and consumed energy, and/or imported and exported energy, or the net energy data.

14. A meter according to any one of claims 1 to 13, further comprising radio tale-switches or ripple control circuitry whereby to facilitate or enable tariff generation or circuit switching.

15. An electricity distribution network including conductors which are connected to an electricity power generation station and to domestic and/or business consumers wherein one consumer is provided with a meter which is sealed in a single enclosure and is operable to meter an amount of electrical energy consumed at a premises and to meter an amount of electrical energy generated at the premises.

16. An electricity supply arrangement where a supplier is operable to supply electrical energy to domestic and/or business consumers wherein a consumer is operable to supply electrical energy from a small scale generation unit by means of a meter according to any one of claims 1 to 14.

17. A method of providing electrical energy to an electricity distribution network by means of a micro-generation unit including a meter in accordance with any one of claims 1 to 14, wherein under conditions of low power consumption by the consumer, power is provided to the network via the meter.

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18. A method of metering electrical energy supplied between a consumer-generator and an electricity distribution network using a meter in accordance with any one of claims l to 14, the method comprising the steps of: metering electrical energy consumed/imported by a consumer from an electricity distribution network, and; metering electrical energy generated/exported from the consumer from an electricity distribution network.