NL2003057C2

NL2003057C2 - SMART UTILITY METERING SYSTEM.

Info

Publication number: NL2003057C2
Application number: NL2003057A
Authority: NL
Inventors: Cornelis Nie; Franciscus Petrus Ridder
Original assignee: Vitelec B V
Priority date: 2009-06-19
Filing date: 2009-06-19
Publication date: 2010-12-21

Description

Smart utility metering system

The present invention is related to a smart utility metering system. It is further related to a utility meter, 5 communication unit and central communication unit for use in such a system. Additionally, it is related to a method for remotely determining utility consumption for a plurality of different subscribers to a service offered by a service provider .

10 Smart utility metering systems are systems which enable a remote reading of a utility meter. An example of such a system is depicted in figure 1. The system comprises a plurality of utility meters, such as an electricity meter 1, a gas meter 2, and a water meter 3. These meters are each 15 coupled to a communication unit 1', 2', 3' which is arranged to transmit utility data. The utility data comprises a utility usage measurement by said utility meter and a data tag indicative for the identity of at least one of the utility meter and the subscriber. For instance, 20 communication unit 3' receives a meter reading from water meter 3. This reading will be sent by communication unit 3' together with for instance the serial number of this meter.

The transmitted utility data is received by a central communication unit 4 over a first communication link 5.

25 Communication unit 4 is further arranged to transmit this utility data to a back-office 6 of the service provider via a second communication link 7 for computation of utility consumption by the subscriber. Most often, back-office 6 will comprise or have access to a database that links 30 subscribers to the utility meters they have. Using this information, as well as the utility usage measurement and data tag, and historical utility consumption information if 2 required, back-office 6 can determine utility consumption for each customer.

The system described above is repeated for each household 8, 9. Furthermore, it is assumed that the utility 5 service provider is responsible for gas, water, and electricity supply. However, it should be obvious that the utility data can also be sent to a plurality of service providers each responsible for a different service. In addition, the utility usage measurement can comprise a meter 10 reading, a cumulative reading, and or other types of statistical information.

Utility meters 1, 2, 3 are typically connected to central communication unit 4 using a wireless communication link. Most often, the utility meters and or the 15 communication units coupled thereto comprise a battery as electrical supply. Power consumption of these circuits is therefore of the utmost important to avoid unnecessary and costly replacements.

An object of the present invention is to provide an 20 alternative to the known smart utility metering system. Further objects of the present invention are that such an alternative system is less costly and that such a system is easier to install and implement.

At least one of these objects is achieved with a smart 25 utility metering system as defined in claim 1. According to the invention, the central communication unit is, at least during operation, connected to plurality of communication units corresponding to plurality of subscribers.

A household typically comprises a plurality of utility 30 meters that correspond to a single subscriber. Each household further comprises a central communication unit that only transmits utility data for that specific subscriber. In the system according to the invention, a 3 single central communication unit communicates with communication units belonging to utility meters of different subscribers. The total number of central communication units in the system can therefore be reduced. It should be noted 5 that the central communication unit is one of the more expensive parts of the system.

To reduce the risk of tampering with the utility meter and or the communication unit coupled thereto, it is advantageous if the communication unit is comprised in a 10 sealed portion of the utility meter.

The central communication unit provides the communication with the back-office of the service provider. This communication is typically long range and requires more electrical power than the shorter range communication 15 between the central communication unit and the various communication units corresponding to the different utility meters. It is therefore advantageous to couple the central communication unit to an electricity meter. This coupling eliminates the need for a separate communication unit, 20 although one may be provided, and it offers the possibility of feeding the central communication unit from a mains network. Furthermore, utility data corresponding to that electricity meter can directly be sent to the central communication unit without making use of a wireless 25 communication link.

The second communication link preferably comprises a Power Line Communication (PLC) link and or a wireless communication link, such as a General Packet Radio Service (GPRS) link. In case of a PLC link, the information can be 30 sent over the same power line that is monitored by the electricity meter connected thereto. The first communication link preferably comprises a wireless Meter-Bus (M-bus) link.

4

Each first communication link has a frequency band associated therewith. This band represents the spectral range signals corresponding to that communication link may have. According to the invention, the M-bus link is 5 preferably set up to operate within a license free ISM band, such as the 868 - 870 MHz band and or the 902 - 928 MHz band. Both the communication unit and central communication unit must be adapted to support these frequency bands, e.g. they must comprise appropriate filters and oscillators. A 10 particular useful frequency range lies between 869.4 MHz and 869.65 MHz. This frequency band allows a higher maximum power to be used, albeit at a duty cycle equal to or less than 10 percent. Choosing this particular frequency range allows the communication units to be spaced apart even 15 further. Hence, more communication units can be coupled or connected to the same central communication unit, allowing even further cost reduction.

At least one of the communication unit and the central communication unit is preferably arranged to regulate a 20 power level of transfer of first signals from one unit to another unit corresponding to said first communication link in dependence of at least one of an integrity and signal strength of a first signal as received by the another unit.

Low power operation is very important for battery 25 operated communication units. Reducing power of emitted signals is one way of reducing the total power consumption of the system. To this end, preferably at least one of the communication unit and the central communication unit has means to regulate the power of emitted signals, e.g. a 30 variable gain amplifier connected to or implemented in a transceiver. In order to reliably reduce the power of emitted signals, one must make sure that the signal is strong enough to guarantee reliable reception. According to 5 the invention, a given unit, being either the communication unit or the central communication unit, sends a signal to the other unit at a given power level. This other unit receives this signal and determines the integrity of this 5 signal and or the signal strength. These findings are reported back to the unit from which the signal originated. Based on these results aspects of the signal transmission, such as the amplification, can be adjusted to achieve low power transmission. In addition, the unit receiving the 10 above mentioned signal can also be adjusted for low power operation. In that case, also that unit transmits a signal for which the integrity and or signal strength will be determined. Both adjustments can take place simultaneously. Furthermore, the signals can be dedicated, which means that 15 they have a predetermined pattern, shape or form to allow the power adjustment. The actual utility data is then transferred at a different time. In addition, the adjustments can be performed during the installation of the system and or they can be carried out continuously or at 20 least during or closely situated to periods of utility data transfer .

It is also advantageous if the communication unit and the central communication unit both comprise a polarization diversity antenna. Each of these antennas is operable in one 25 of a plurality of polarization states. Typically, a polarization diversity antenna comprises several individual antennas or antenna parts that are placed at a certain orientation with respect to each other. By using these antennas or parts differently, e.g. by driving one more than 30 the others, signals can be transmitted with differing polarizations .

A polarization state according to the invention relates to a specific way the polarization diversity antenna is 6 driven or operated to obtain a given polarization of the transmitted signal. The communication unit and the central unit are preferably arranged to set the polarization state of the corresponding antenna based on the integrity and or 5 signal strength of a signal received at the other unit. In this case, a similar approach is used as with the adjustment of signal power described earlier. Also here, simultaneous adjustment of both units is possible. If an antenna has two different polarization states, with this antenna being 10 implemented in both units, four polarization combinations are possible. The optimum polarization state, in terms of integrity and or signal strength, can then be determined. Some sort of handshaking may be involved between the different units to ensure an efficient adjustment process.

15 As with the adjustments of signal power, the adjustments regarding polarization states can be performed during the installation of the system and or they can be carried out continuously or at least during or closely situated to periods of utility data transfer.

20 It is advantageous if a battery operated communication unit and or central communication unit comprises a capacitor placed parallel to the battery. From prior art systems it has been determined that units no longer were able to reliable transmit data, although the battery voltage as such 25 was sufficient. It has been found that peak currents drawn from the battery during signal transfer reduce the available battery voltage at that time. By shunting the battery with a capacitor, this problem can be obviated.

Further benefits can be achieved by placing a switch in 30 between the battery and capacitor. This switch is controllable to put the relevant unit in a idle mode, in which no signals are sent, or in an active mode for sending signals. By disconnecting the battery from the capacitor, 7 unnecessary power loss, for instance due to leakage currents, is prevented. The switch can be controlled by the relevant unit. To this end, the unit may comprise a microcontroller with a timer associated therewith. The timer 5 can be used for determining the points in time at which utility data must be sent or received.

The present invention also provides a communication unit, a central communication unit, and a utility meter suitable for use in a smart utility metering system, as 10 previously defined.

Additionally, the present invention provides a method for remotely determining utility consumption for a plurality of different subscribers to a service offered by a service provider. According to the invention, the method comprises 15 the steps of measuring utility usage pertaining to said plurality of subscribers and transmitting a plurality of utility data corresponding to said plurality of subscribers to a central communication unit using a first communication link. Each utility data comprises a utility usage 20 measurement and a data tag indicative for the identity of at least one of a corresponding utility meter and a corresponding subscriber. The method further comprises the steps of receiving the plurality of utility data at the central communication unit and transmitting the plurality of 25 utility data from the central communication unit to a back-office of said service provider using a second communication link.

Preferably, the first communication link comprises a wireless Meter-Bus (M-bus) link within a 869.4 - 869.65 MHz 30 band. Additionally, the transmitting and receiving of said plurality of utility data is preferably performed using polarization diversity antennas, each antenna being operable in one of a plurality of polarization states. The method 8 further comprises adjusting the polarization states of the antennas in dependence of at least one of an integrity and signal strength corresponding to said first communication link.

5 Although emphasis has been laid on the communication of utility data from the utility meter to the back-office, information may also be sent from the back-office to the utility meter. This information may comprise meter settings or statistical data to be used by the subscriber. It should 10 be obvious to the skilled person that the components, techniques and methods can easily be modified to support this functionality.

Next, the invention will be described in more detail using the accompanying figures, wherein: 15 Figure 1 schematically illustrates a known smart utility metering system;

Figure 2 shows an embodiment of the present invention demonstrating the general concept;

Figure 3 illustrates an embodiment of a communication 20 unit according to the present invention.

The embodiment of the smart utility metering system illustrated in figure 2 demonstrates the general concept of the invention. Compared to the prior art system depicted in figure 1, households 8 and 9 now share a single central 25 communication unit 4. Furthermore, central communication unit 4 is connected to electricity meter 1. A separate communication unit is therefore deemed unnecessary.

Figure 3 depicts an embodiment of a communication unit 10 according to the present invention. The communication is 30 fed by a battery 11. The functionality of the communication unit is realized in a RF module 12. This module transmits the utility data using a polarization diversity antenna which comprises two antenna parts 13, 13' placed at an angle 9 of 90 degrees with respect to each other. A switch 14, which is controllable by RF module 12, is used to switch between different polarization states. Other embodiments are foreseen in which switch 14 is replaced by a signal divider 5 to divide the signal from RF module 12 over the antenna parts 13, 13' .

The use of a polarization diversity antenna increases the range of the wireless M-bus communication link. Antennas usually display a radiation pattern that strongly depends on 10 the direction of propagation of the emitted electromagnetic wave. If the communication unit and the central communication unit were to have typical antennas, the problem may occur that due to the placement of the utility meter, the electromagnetic propagation path between both 15 units corresponds to a direction for which the antenna(s) are less sensitive. Using polarization diversity antennas obviates this problem.

Figure 3 further illustrates a capacitor 15 that shunts battery 11. This capacitor acts as a current buffer.

20 A property of high capacity batteries (Li/SOCl2) which are typically used for smart utility metering systems, is that during the life span of the battery, a passivation effect occurs due to which the internal resistance of the battery will increase. A consequence of this increase is 25 that at high currents, the voltage at the terminals of battery 11 will drop.

To ensure stable operation, RF module 12 requires a minimum voltage for transmitting the utility data. Without special precautions, the peak current drawn from battery 11 30 will bring the available battery voltage below this minimum voltage. Consequently, RF module 12 will cease to operate.

Capacitor 15, placed in parallel to battery 11, will obviate this problem. When a high current is required, e.g.

10 during transmission of utility data, capacitor 15 will discharge, providing an additional current component to the current supplied by battery 11.

Communication unit 10 will send a T1 message, 5 corresponding to the EN13757-4 standard, at a rate of 4 times per hour. These messages are one way only, which means that only meter readings are sent to the central communication unit. The duration of a T1 message is approximately 1.5 seconds. Additionally, communication unit 10 10 will send a T2 message, according to the EN13757-4 standard, once an hour. In addition to sending the meter readings, a possibility is offered for sending messages from the central communication unit back to the communication unit. The total duration for this T2 message is 15 approximately 1.7 seconds. Communication unit 10 is therefore only active for 7.7 seconds per hour. This indicates that current consumption during the idle mode is of utmost importance.

A disadvantage of capacitor 15 is that it provides a 20 path for a leakage current from battery 11 through capacitor 15. To obviate this problem, a switch 16, e.g. a FET transistor, is placed in between battery 11 and capacitor 15. When switch 16 is opened, leakage currents will only flow as long as the capacitor is charged. The leakage will 25 discharge the capacitor and therefore after some time, this leakage will stop. Switch 16 is controllable by RF module 12. This module will close switch 16 during the active mode. It may be foreseen that switch 16 is closed a short period of time before the actual transmission of data to allow 30 capacitor 15 to charge.

Although the invention has been described using embodiments thereof, this description should not be interpreted as limiting the scope of the invention to those 11 embodiments only. It should be obvious to the skilled person that various modifications are possible without deviating from this scope which is described in the appended claims.

Claims

A smart gas / water / electricity measuring system, comprising: 5. a gas / water / electricity meter for measuring gas / water / electricity consumption concerning a subscriber to a gas / water / electricity service that is offered by a utility company; a communication unit coupled to the gas / water / electricity meter and adapted to send gas / water / electricity data comprising a gas / water / electricity consumption measurement by said gas / water / electricity meter and a data label which is characteristic is for the identity of at least one of the gas / water / electricity meter and the subscriber; a central communication unit adapted to receive the gas / water / electricity data from the communication unit using a first communication connection and for sending this gas / water / electricity data to a back office of said utility for calculation of gas / water / electricity consumption by said subscriber using a second communication connection; wherein during operation said central communication unit is connected to a plurality of said communication units corresponding to a plurality of subscribers.

2. Smart gas / water / electricity measuring system according to claim 1, "wherein the communication unit is included in a sealed portion of the gas / water / electricity meter.

Smart gas / water / electricity measurement system according to claim 1 or 2, wherein the central communication unit is coupled to an electricity meter.

4. Smart gas / water / electricity measurement system according to any of the preceding claims, wherein the second communication connection comprises a power line communication (PLC) connection and or a wireless communication connection, such as a general packet radio service (GPRS) connection.

Smart gas / water / electricity measurement system according to any of the preceding claims, wherein the first communication connection comprises a wireless meter-bus (M-bus) connection.

The smart gas / water / electricity measurement system according to claim 5, wherein the central communication unit and the communication unit are arranged for realizing said Μ-Bus connection in a license-free ISM band, such as the 868-870 MHz band and or the 902-928 MHz band.

The smart gas / water / electricity measurement system according to claim 6, wherein the central communication unit and the communication unit are adapted to implement said Bus-Bus connection in the 869.4-869.65 MHz band.

8. Smart gas / water / electricity measuring system according to one of the preceding claims, wherein at least one of the communication unit and the central communication unit is arranged for controlling a power level of transmission of first signals from one unit to a another unit corresponding to said first communication link in dependence on at least one of an integrity and a signal strength of a first signal as received by the other unit.

9. Smart gas / water / electricity measurement system according to claim 8, wherein the communication unit and the central communication unit both comprise a polarization diversity antenna, wherein each antenna is active in one of a plurality of polarization states, the communication unit and the central communication unit are each adapted to set the polarization state of the corresponding antenna in dependence on said at least one of an integrity and signal strength of a first signal as received by the other unit.

A smart gas / water / electricity measuring system according to any one of the preceding claims, wherein at least one of the communication unit and the central communication unit 10 comprises a battery for supplying said unit, said battery being connected in parallel to a capacitance, the relevant unit further comprising a switch between the battery and capacitance, the said switch being controllable for bringing the relevant unit to a rest state at which no signals are sent, or in an active state for transmitting signals.

11. Communication unit suitable for use in a smart gas / water / electricity metering system, as defined in any one of claims 1-10.

12. Central communication unit suitable for use in a smart gas / water / electricity measurement system, as defined in any one of claims 1-10.

13. Gas / water / electricity meter suitable for use in a smart gas / water / electricity measuring system, wherein the gas / water / electricity meter is arranged as the gas / water / electricity meter as defined in any one of claims 1-10 to that extent dependent on claim 2.

14. Method for remotely determining gas / water / electricity consumption for a plurality of different subscribers to a service offered by a utility company, said method comprising the steps of: measuring gas / water / electricity consumption concerning the said plurality of subscribers; transmitting a plurality of gas / water / electricity data corresponding to said plurality of subscribers to a central communication unit using a first communication link, wherein each gas / water / electricity data comprises a gas / water / electricity consumption measurement and a data label characteristic of the identity of at least one of a corresponding gas / water / electricity meter and a corresponding subscriber; receiving the plurality of gas / water / electricity data at the central communication unit; transmitting the plurality of gas / water / electricity data from the central communication unit to a back office of said utility using a second communication connection.

The method of claim 14, wherein the first communication link comprises a wireless meter-bus (M-Bus) connection in an 869.4-869.65 MHz band.

16. A method according to claim 15, wherein said transmitting and receiving said plurality of gas / water / electricity data is performed using polarization diversity antennas, each antenna operating in one of a plurality of polarization states, said method further comprises adjusting the polarization states of said antennas in dependence on at least one of an integrity and signal strength corresponding to said first communication connection.