GB2492845A

GB2492845A - Gas meter power supply which uses remote light source, optical fibre and photovoltaic cell to charge battery

Info

Publication number: GB2492845A
Application number: GB1112207.4A
Authority: GB
Inventors: Paul Richard Rowe; Chris Lemondine Martin; Chris Shelley; Christopher Saunders; Jim Donaldson; Malcolm Mcculloch
Original assignee: NAVETAS ENERGY MAN Ltd
Current assignee: NAVETAS ENERGY MAN Ltd
Priority date: 2011-07-15
Filing date: 2011-07-15
Publication date: 2013-01-16
Also published as: WO2013011287A2; WO2013011287A3; GB201112207D0

Abstract

The invention relates to utility meters and to a means for providing power to a utility meter 1. In particular the invention relates to a method for recharging an internal power supply in a gas meter 2. A power supply system for a utility meter comprises a photovoltaic device ( 36 figure 2) connected to an internal power source of a utility meter 2, a light source 38 provided at a distance from the utility meter, and light transmitting means 4 arranged to transmit light from the light source to the photovoltaic device. The photovoltaic device provides electrical energy to recharge the internal power source 30 of the utility meter. The internal power source or battery 30 may be a capacitor, or a supercapacitor or a double layered capacitor. In one embodiment (figure 2) hybrid layer capacitors HLC 34 are used along with Lithium Thionyl Chloride batteries. The power supply system may also comprise a means of communicating with a remote host 6 by means of optical fibre 8 arranged to transmit data signals between the utility meter and the transmitting means. An interface may be arranged on the meter which also comprises a second transceiver 28 arranged to transmit optical signals along the optical fibre 8 to the transmitting means, and to receive optical signals transmitting means via the optical fibre 8, and a control circuitry arranged to control the operation of the second transceiver and the optical energy to electrical energy converter in order for data signals and light emitted by the light source conveyed by the optical fibre.

Description

IMPROVEMENTS IN AND RELATING TO UTILITY METERS

FIELD OF THE INVENTION

The present invention relates to utility meters and to a means for providing power to a utility meter. More specifically the present invention relates to a method for recharging an internal power supply in a gas meter.

BACKGROUND TO THE INVENTION

Smart utility meters can be used to take meter readings automatically, so that meter readings can be taken at regular intervals or on-demand. This allows customers and/or utility suppliers to monitor energy usage and adjust usage or supply accordingly. Smart meters include means for transferring data from the meter to a remote host via a network.

Generally, current systems are battery powered. However, battery life is limited and typically it is the battery that determines the life of the meter. Batteries can last between five and ten years, but with greater functionality being introduced into smart metering, such that frequent data transfer is required, this lifetime can be greatly reduced.

Any installation in a utility meter must be intrinsically safe. This is of particular concern with gas meters. A safe distance between the gas meter and any electrical items must be maintained in order to minimise the risk of a potential electrical fault causing an explosion. In many cases, gas meters are encased inside a meter box or other enclosed area. If a gas leak occurred, it is likely that the enclosed area would fill with gas, increasing the safety concerns. The use of mains electricity in water meters is potentially hazardous due to the risk of electric shock if the electricity supply were to make contact with the water. It is, therefore, not possible to make any form of electrical connection to the gas meter in order to power the gas meter or to recharge the batteries within the gas meter.

It is an object of the present invention to provide means for providing power to a utility meter that overcomes at least some of these problems.

It is an aim of the present invention to overcome at least one problem associated with the prior art whether referred to herein or otherwise.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention there is provided a power supply system for a utility meter, the system comprising: -an optical energy to electrical energy converter connected to an internal power source of a utility meter; -a light source provided at a distance from the utility meter; and -light transmitting means arranged to transmit light from the light source to the optical energy to electrical energy converter, wherein, in use, the optical energy to electrical energy converter provides electrical energy to recharge the internal power source.

Preferably the optical energy to electrical energy converter comprises a photovoltaic device.

Preferably the light transmitting means comprises an optical fibre.

Preferably the internal power source comprises a rechargeable power source and may comprise a rechargeable battery.

The internal power source may comprise a battery or may comprise a capacitor.

The internal power source may comprise a hybrid layer capacitor.

The internal power source may comprise a super capacitor.

The internal power source may comprise an electric double layer capacitor.

Preferably the utility meter comprises a gas meter.

The light source may comprise a light emitting diode (LED).

Preferably the power supply system further comprises transmitting means for communicating with a remote host, and wherein the light transmitting means comprises an optical fibre arranged in use to transmit data signals between said utility meter and the transmitting means.

Preferably the utility meter comprises a meter interface for processing the data signals transmitted by the optical fibre.

Preferably the photovoltaic device comprises a photovoltaic cell connected to the meter interface.

Preferably the transmitting means includes a first transceiver which is arranged, in use, to transmit optical signals along the optical fibre to the utility meter and to receive optical signals from the utility meter via the optical fibre.

Preferably the first transceiver comprises the light source.

Preferably the meter interface comprises: -a second transceiver arranged, in use, to transmit optical signals along the optical fibre to the transmitting means, and to receive optical signals from the transmitting means via the optical fibre; and -control circuitry arranged, in use, to control the operation of the second transceiver and the optical energy to electrical energy converter in order for data signals and light emitted by the light source to be conveyed by the optical fibre.

The power supply system may include a utility meter and wherein the utility meter comprises a gas meter.

According to a second aspect of the present invention there is provided a method of supplying power to a utihty meter, the method comprising the steps of: -emitting light from a light source located remote from the utility meter; -conveying the emitted light through light transmitting means to said utility meter; -receiving said conveyed light and converting said light into electrical energy by means of an optical energy to electrical energy converter in said utility meter; and -using the electrical energy to recharge an internal power source of said utility meter.

Preferably the method comprises converting said light into electrical energy by means of a photovoltaic device.

Preferably the method further comprises transmitting data signals between the utility meter and transmitting means located remote from the utility meter, and wherein the data signals and the emitted light are both conveyed through the same light transmitting means.

Preferably the method further comprises controlling the operation of the light source, optical energy to electrical energy converter and the transmission of data signals, such that, when the light transmitting means is not used to transmit data signals, the light source is illuminated and the light transmitting means is used to convey emitted light to the optical energy to electrical energy converter for the generation of electrical energy.

Preferably the method comprises supplying power to a gas meter.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be further described, by way of example only, and with reference to the accompanying drawings, in which: Figure 1 is a schematic view of a smart utiHty meter system according to the present invention; and Figure 2 is a schematic view of a power system including an optical fibre according to a preferred embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Figure 1 shows a schematic of a smart utility meter system 1. In this example the meter system 1 comprises a gas meter 2. However, the system may include any type of utility meter or similar and, in particular, may relate to water meters or electricity meters.

The utility meter system 1 further comprises transmitting means 4 for communicating with a remote host 6 and optical communication means 8 connecting the meter 2 to the transmitting means 4. In this example the optical communication means 8 comprises light transmitting means in the form of a single optical fibre or a bundle of optical fibres 8.

The optical fibre connection 8 from the meter 2 to the transmitting means 4, allows the transmitting means 4 to be located at a safe distance from the meter 2. The transmitting means is, therefore, not restricted to the use of a very low power source and the transmitting means 4 can be used to transmit data frequently and as and when required. The use of a low power source would restrict the use of the transmitting means 4 such that it would only be able to transmit meter readings infrequently and it would have a short life span as the power source quickly expires.

The transmitting means 4 transmits data from the meter 2 to the remote host 6 via a network 10 or other wireless means and processes control signals from the remote host 6, which are subsequently used to control the meter 2. The remote host 6 may be a utility company or other company responsible for billing or for maintenance of the meter 2, or the remote host 6 may comprise a control centre in a user's home so that the user may monitor their gas usage by means of data transmitted from the utility meter 2.

The gas meter 2 typically has a display 12 which shows the current meter reading.

This display 12 may be mechanical, but more recently is more typically a battery powered liquid crystal display (LCD).

The meter 2 also includes a meter interface 14 which is permanently installed in the meter 2. This interface 14 is adapted to receive data from and transmit data to the meter 2. In particular, the meter interface 14 will typically comprise a printed circuit board and one or more sensors 16 for collecting data from the meter 2 and in particular for obtaining the current meter reading. Other forms of data may also be collected from the meter 2, for example gas flow rates or battery life. The meter interface 4 further comprises control circuitry 18, which may include a microprocessor 20, that is used to control various aspects of the running of the meter 2.

To enable communication between the meter 2 and the transmitting means 4, a first transceiver 22 is connected to or provided on the meter interface 4 and is in communication with a first end 24 of the optical fibre 8. The transceiver 22 sends signals from the meter 2 along the optical fibre 8, and receives signals from the transmitting means 4 via the optical fibre 8. Typically the first transceiver 22 is an opto-electronic transceiver 22 able to both transmit and receive electrical and optical signals. In a preferred embodiment, the first transceiver 22 comprises a light emitting diode (LED). The LED acts as both a transmitter and a receiver.

A second end 26 of the optical fibre 8 is aligned with and in communication with a second transceiver 28 provided in the transmitting means 4. This second transceiver 28 is typically also an opto-electronic transceiver 28 and sends signals from the transmitting means 4 along the optical fibre 8 to the meter 2, and receives signals from the meter 2 via the opticai fibre 8 and communicates them to the transmitting means 4.

In order to power the meter interface 4, a very low voltage power supply 30 is required. This will generally be a battery 30 connected to the printed circuit board.

Alternatively, if a battery is already used within the meter 2 to power, for example, the display 12, then the meter interface 4 may be connected to this battery.

It is not desirable to incorporate removable batteries into a utility meter 2, to allow the batteries to be replaced or recharged, as this may introduce problems with users being able to tamper with the system. It is possible to replace batteries inside a gas meter but these have to reside under tamper proof covers. However, it is not desirable to replace batteries because there are some issues with doing this. For example, an engineer would generally have to visit the site and gain access to the gas meter, which is costly since a consumer could not replace the batteries. In addition, the batteries typically have a "shelf life" and therefore stock management is of importance, again adding cost. Furthermore, there are some issues that can be caused by having a removable electrical contact with replaceable batteries, where corrosion can occur at the contacts.

Additionally, it is not possible to provide an electrical connection to the meter 2 to recharge the battery 30, as described above. As such, currently, the lifetime of the battery 30 limits the life of the whole meter 2.

A gas meter 2, or other utility meter, may be powered by any suitable battery, however, Lithium Thionyl Chloride batteries are a preferred choice as they have a relatively long life (greater than 10 years) compared to other batteries. However, one problem with these batteries is that, by their very nature, they are not rechargeable.

One particular gas meter design, illustrated in Figure 2, incorporates Lithium Thionyl Chloride batteries 32 and a hybrid layer capacitor (HLC) 34, also known as an electric double layer capacitor or a supercapacitor. The HLC 34 functions both as a capacitor and a battery and may be recharged very quickly.

When high currents are drawn by the gas meter 2, for example when the gas meter 2 is transmitting data or when a gas solenoid valve (not shown) is operated to stop a flow of gas, then the voltage available from the lithium batteries 32 reduces because of the internal resistance of the batteries 32. This can have a negative effect if the voltage reduction is severe enough to fall below certain levels.

To compensate for this, the HLC 34 is used in conjunction with the lithium batteries 32. The HLC 34 maintains a constant voltage level to the gas meter 2 because it does not have the internal resistance problems of the lithium battery 32.

It can also deliver significantly large amounts of current for short time periods. As such, in practice, the HLC or supercapacitor 34 provides the current when the gas meter 2 is in operation, and the lithium batteries 32 are used to recharge the HLC or supercapacitor 34.

The present invention utilises the presence of the optical fibre 8 to provide power to recharge the HLC 34, together with, or in place of, the lithium batteries 32. In particular, the system of the present invention comprises an optical energy to electrical energy converter in the form of a photovoltaic device 36 to convert light energy transmitted via the optical fibre 8 into electrical energy to recharge the batteries 32 and/or the HLC 34.

Data signals sent along the optical fibre 8 between the meter 2 and the transmitting means 4 are typically infrequent, so that the signals are only sent about 1% of the time. Therefore, there is a large amount of time, of the order of 99% of the time, when the optical fibre 8 is not be used to transmit data signals.

The present invention uses this existing optical link 8 to the gas meter 2 to provide additional power during time of no communication when the meter 2 is in standby mode'.

The standby mode' is defined as the normal operational mode of the smart utility meter 2, when the meter 2 is only measuring, for example, the amount of water or gas used without any interaction by the consumer or any data being sent to or received from the transmitting means 4. In this standby mode most peripheral devices, including the display means 12, in the meter 2 are switched off in order to preserve battery life. The meter 2 will typically be in this mode most of the time, during which only a small amount of current will be consumed, typically in the region of 10 micro amperes.

As shown in Figure 2, the first end 24 of the optical fibre 8 is aligned with the first optical transceiver 22, as previously described, and additionally a photovoltaic cell 36. The second end 26 of the optical fibre 8 is aligned with the second transceiver 28 which includes a light source 38, which in this example is an LED.

When data is not being transmitted between the meter 2 and the transmitting means 4, the LED 38 in the second transceiver 28 emits light into the second end 26 of the optical fibre 8. This light is conveyed along the optical fibre 8 and at the first end 24 of the optical fibre 8 the conveyed light strikes the photovoltaic cell 36.

The cell 36 converts the optical energy conveyed by the optical fibre 8 into electrical energy.

The electrical energy is used to recharge the HLC 34 and/or provide power to the meter 2. In this way, the amount of current taken over time from the lithium batteries 32 is vastly reduced, meaning that the lifetime of the lithium batteries 32, and therefore the lifetime of the gas meter 2, is increased. Preferably the combination of optical fibre 8 and photovoltaic cell 36 is able to generate a current -10-of more than 10 micro amperes (the amount of current drawn in standby mode) and, as such, the operation of the gas meter 2 may be powered directly from the generated electrical energy so that the lithium batteries 32 are not used during these times. Any excess electrical energy, not used to directly power the meter 2, is then used to assist in recharging the HLC 34.

The control circuitry 18 or microprocessor 20 is arranged to control the operation of the first transceiver 22 and the photovoltaic cell 36 so as to optimise the balance between the communication and transmission of data signals along the optical fibre S and the generation of electrical energy from light energy conveyed along the same optical fibre 8.

In this way, the present invention utilises an existing and intrinsically safe optical communication means 8 to provide power to operate a utility meter 2 and recharge self-contained power sources 30 within the meter 2 through the use of a photovoltaic cell 36 provided within the meter 2 and a light source 38 provided externally and at a distance from the meter 2.

Claims

<claim-text>CLAIMS1. A power supply system for a utility meter, the system comprising: -an optical energy to electrical energy converter connected to an internal power source of a utility meter; -a light source provided at a distance from the utihty meter; and -light transmitting means arranged to transmit light from the light source to the optical energy to electrical energy converter, wherein, in use, the optical energy to electrical energy converter provides electrical energy to recharge the internal power source.</claim-text> <claim-text>2. A power supply system according to Claim 1 in which the optical energy to electrical energy converter comprises a photovoltaic device.</claim-text> <claim-text>3. A power supply system according to Claim 1 or Claim 2 in which the light transmitting means comprises an optical fibre.</claim-text> <claim-text>4. A power supply system according to any preceding claim in which the internal power source comprises a battery or capacitor.</claim-text> <claim-text>5. A power supply system according to any preceding claim in which the internal power source comprises a hybrid layer capacitor.</claim-text> <claim-text>6. A power supply system according to any preceding claim in which the internal power source comprises a super capacitor.</claim-text> <claim-text>7. A power supply system according to any preceding claim in which the internal power source comprises an electric double layer capacitor.</claim-text> <claim-text>8. A power supply system according to any preceding claim in which the utility meter comprises a gas meter. -12-</claim-text> <claim-text>9. A power supply system according to any preceding claim in which the light source comprises a light emitting diode.</claim-text> <claim-text>10. A power supply system according to any preceding claim in which the system further comprises transmitting means for communicating with a remote host, and wherein the Hght transmitting means comprises an optical fibre arranged in use to transmit data signals between said utility meter and the transmitting means.</claim-text> <claim-text>11. A power supply system according to Claim 10 in which the utility meter comprises a meter interface for processing the data signals transmitted by the optical fibre.</claim-text> <claim-text>12. A power supply system according to Claim 11 when dependent upon Claim 2 in which the photovoltaic device comprises a photovoltaic cell connected to the meter interface.</claim-text> <claim-text>13. A power supply system according to Claim 11 or Claim 12 in which the transmitting means includes a first transceiver which is arranged, in use, to transmit optical signals along the optical fibre to the utility meter and to receive optical signals from the utility meter via the optical fibre.</claim-text> <claim-text>14. A power supply system according to Claim 13 in which the first transceiver includes the light source.</claim-text> <claim-text>15. A power supply system according to any one of Claim 11 to Claim 14 in which the meter interface comprises: -a second transceiver arranged, in use, to transmit optical signals along the optical fibre to the transmitting means, and to receive optical signals from the transmitting means via the optical fibre; and -control circuitry arranged, in use, to control the operation of the second transceiver and the optical energy to electrical energy converter in order for data -13-signals and light emitted by the light source to be conveyed by the optical fibre.</claim-text> <claim-text>16. A power supply system according to any preceding claim in which the power supply system includes a utility meter and wherein the utility meter comprises a gas meter.</claim-text> <claim-text>17. A method of supplying power to a utility meter, the method comprising the steps of: -emitting light from a light source located remote from the utility meter; -conveying the emitted light through light transmitting means to said utility meter; -receiving said conveyed light and converting said light into electrical energy by means of an optical energy to electrical energy converter in said utility meter; and -using the electrical energy to recharge an internal power source of said utility meter.</claim-text> <claim-text>18. A method of supplying power to a utility meter according to Claim 17 in which the method comprises converting said light into electrical energy by means of a photovoltaic device.</claim-text> <claim-text>19. A method of supplying power to a utility meter according to Claim 17 or Claim 18 in which the method further comprises transmitting data signals between the utility meter and transmitting means located remote from the utility meter, and wherein the data signals and the emitted light are both conveyed through the same light transmitting means.</claim-text> <claim-text>20. A method of supplying power to a utility meter according to Claim 19 in which the method further comprises controlling the operation of the light source, optical energy to electrical energy converter and the transmission of data signals, such that, when the light transmitting means is not used to transmit data signals, the light source is illuminated and the light transmitting means is used to convey -14-emitted light to the optical energy to electrical energy converter for the generation of electrical energy.</claim-text> <claim-text>21. A method of supplying power to a utility meter according to any one of Claim 17 to Claim 20 in which the method comprises supplying power to a gas meter.</claim-text> <claim-text>22. A power supply system substantially as herein described with reference to, and as shown in, any of the accompanying drawings.</claim-text> <claim-text>23. A method of supplying power to a utility meter substantially as herein described with reference to, and as shown in, any of the accompanying drawings.</claim-text>