GB2297850A - Improvements in and relating to the metering of a commodity - Google Patents

Abstract

A meter, for metering the supply of a commodity such as electricity to a consumer is operable to monitor the consumption of the commodity over a succession of periods, over the first of which the consumption of the commodity over a succession of intervals is measured and stored. For each subsequent period, the amount of commodity consumed over a succession of corresponding intervals, each of which corresponds to a respective interval in the first period, is measured. This process is repeated for a succession of periods so that measurements are obtained for a number of sets of intervals, all of the intervals in each set corresponding to the same respective part of the period. The meter then generates an output representative of the average power consumed per interval for each set. The metering may measure average consumption day-by-day over each 30 minute interval in the period of 24 hours. The necessary circuitry may be enclosed in an add-on unit 2 to a normal meter. The average levels may be read out to a magnetic card inserted into slot 4.

Description

IMPROVEMENTS IN AND RELATING TO THE METERING OF A COMMODITY Field of the Invention This invention relates to a method of, and apparatus for, metering the supply of a commodity, for example electricity, gas or water.

Background to the Invention In order to charge a consumer for the use of a commodity, it is well known to use a meter to measure the commodity used. The meter is read periodically and the consumer charged according to the amount of commodity used in the period in question. Thus, for example, an electricity meter can record the total number of kilowatt hours consumed at a premises, and is read quarterly so that the consumer is charged for the number of kilowatt hours used in the previous quarter.

It is possible for the rate at which the consumption of the commodity is charged to vary over time. For example, in the case of electricity, it is well known to provide a two-tier tariff in which electricity consumed at night is much cheaper than electricity consumed during the day. It is desirable, in some circumstances, to provide a more sophisticated tariff structure in which a charging rate can vary from, for example, hour to hour in any given day, from week to week or from season to season. Such a structure could be used to provide an incentive for people to use the commodity at a time when it can be most cheaply supplied to them or to cut down use of the commodity at times of relatively high demand.

In order to implement such a tariff structure, a meter could be arranged so that the amount of the commodity consumed over a succession of intervals (each of half an hour for example) is stored along with the time at which said consumption occurred. However, the storage of such data would require large amounts of non-volatile memory in the meter, making it costly.

Alternatively, the consumer could agree with the supplier a time profile to be applied to the metered consumption so as to allow the consumer to take advantage of the tariff structure in use. However, such profiles would be very general, and based on the activities of all users, as a result of which the particular customer's use may not follow the pattern predicted by the profile. Thus this approach could lead to disputes between the consumer and the supplier.

Summarv of the Invention According to a first aspect of the invention, there is provided a method of metering a supply of a commodity to a consumer over a succession of periods, the method comprising the steps of monitoring the consumption of the commodity over a succession of intervals in the first of said periods and storing a plurality of values each related to the amount of commodity consumed in a respective interval; for each subsequent period, monitoring the amount of commodity consumed over a succession of corresponding intervals each of which is part of a respective set of intervals, in different periods, all corresponding to the same respective part of said periods; modifying each value so that it is representative of an average of the amount of commodity consumed in an interval of a respective set; and generating an output representative of said averages.

By calculating the averages of the consumption of commodity the method provides an indication of the amounts of commodity consumed at different stages of any given period.

Moreover, the memory of apparatus for performing this method only requires a number register for storing the number of periods previously monitored, and a number of addresses corresponding to the number of intervals in each period so that the average value for each set of intervals can be stored at a respective one of the addresses.

The average is preferably a mean average. This may be calculated by adding to each value for the first period further values representative of the total amount of commodity consumed in the subsequent corresponding intervals, so that each value represents the total amount consumed in the intervals of its respective set, and then dividing the value by the total number of intervals in the set.

Alternatively, the final value can be calculated by updating an average value on an ongoing basis as each period is monitored. This can be done by, for example, storing the number of periods previously monitored in a number register, incrementing the register by one when the monitoring of the next period begins; for each interval in said next period, subtracting the respective average value previously calculated from a current value representative of the amount of commodity consumed in said interval of the next period, dividing the resulting difference by the number in the number register to give a quotient which is then added to said previously calculated average value.

In this way, an average for each set of intervals is available whenever the memory of the apparatus which performs the method is interrogated.

The output may be incorporated in a signal transmitted to processing apparatus remote from the location at which said metering occurred, said processing apparatus being arranged to calculate the charge incurred by the use of the commodity.

Such a signal may be an electromagnetic signal, or a signal transmitted along a phone line or a mains electrical power line connecting the processing apparatus to the location at which the metering occurred.

Alternatively, the output may be stored on a portable card (commonly referred to as a "smartcard") which can be removably accommodated in the apparatus for pertroming the metering, and which can be transferred from said apparatus to said processing apparatus at which the data stored on the card is read.

This feature facilitates installation of the apparatus for performing the metering because the need for any infrastructure providing a link between the apparatus and the remote processing apparatus is avoided.

Conveniently, the method is performed by metering apparatus arranged to accommodate said card, and the power to operate the metering apparatus is provided by a power source mounted on the card.

Preferably, the metered commodity is electricity, in which case each period can comprise one day, and each interval is of 30 minutes duration, so that each period has a total of 48 intervals.

According to a second aspect of the invention there is provided metering apparatus for metering the consumption of a commodity over a succession of periods, the apparatus comprising a clock for determining the beginnings and endings of the periods and, for each period, the beginnings and endings of a succession of intervals spanning said period; monitoring means for monitoring the amount of commodity consumed in each of said intervals; calculating means for calculating the average amounts of commodity consumed per interval for each of a plurality of sets of intervals, all the intervals in each set corresponding to the same respective part of said periods; and memory means for storing a plurality of values, each representative of a respective average.

Preferably, the apparatus includes means for receiving a removable card on which said values are recorded.

Preferably, said apparatus comprises a first part which contains at least part of the monitoring means for measuring the amount of commodity used, and means for transmitting data to a second part having receiving means for receiving said data, said second part containing said clock, memory and calculating means, wherein said first and second parts are separable.

This enables the first part to be installed separately from the second part, and to be used in a similar manner to a conventional meter which measures the total amount of commodity used, but does not provide any clear information on the distribution of that use over any particular charging period. The meter can readily be upgraded to perform the metering method of the present invention simply by the addition of the second part.

Conveniently, the transmission means and receiving means comprise an inductive link between the two parts.

The invention also lies in apparatus according to the second aspect of the invention, adapted to receive a removable card on which said values are recorded, and which preferably also includes a battery for powering said apparatus.

Brief Description of the Drawings The invention will now be described, by way of example only, with reference to the accompanying drawings which show electricity metering apparatus comprising two parts, and in which: Figures 1 and 2 show a first part of the apparatus respectively from the front and one side; Figures 3 and 4 are corresponding views of the first and second parts; and Figure 5 is a functional block diagram of various components of the apparatus.

Detailed Description The parts shown in Figures 1 and 2 comprises a single phase watt hour electricity meter for metering the supply of single phase ac mains electricity to a domestic customer. The meter measures the number of watt hours used in the premises, stores that number in a number register (not shown) and also displays the number on an LCD display 1.

The meter can be used in the same way as a conventional electricity meter, in which case the number on the display is read periodically (usually quarterly) and subtracted from the previous reading to obtain the number of watt hours used over the charging period in question.

However, the meter can alternatively be used with a second part in the form of a profiling module 2 mounted on top of the meter (Figures 3 and 4). The module 2 reads the number of watt hours registered on the meter, and calculates a series of values which represent the average profile of electricity consumption throughout a day in the charging period. These values are recorded on a smartcard (not shown) which is received in a slot 4 in the front of the module 2. As can be seen from Figure 3, the front of the module 2 also includes a tapered mouth 5 which terminates at its inboard end at the slot 4 and which facilitates insertion of the card into the slot 4.

With reference to Figure 5, the meter includes a serial data transmitter 6 which uses low frequency induction to transmit data to a receiver 8 in the profiling module 2. The transmitter 6 reads the number in the number register of the meter (the same as the number displayed on the display 1) and encodes that number by modulating a current fed to an inductive coil (not shown) of the transmitter 6. The data receiver 8 includes a coil in which an emf is generated as a result of the magnetic field produced by the coil of the transmitter 6, and which therefore picks up the signal transmitted by this transmitter 6.

The receiver 8 includes circuitry for decoding the signal from the transmitter 6 so that the module 2 can read the number of watt hours in the register of the meter.

In a simplified embodiment, the transmitter could be arranged to transmit a single pulse signal every time the number register of the meter is incremented, in which case the profiling module 2 would obtain a measure of the number of watt hours consumed in a period simply by counting the number of pulses received during that period.

The data receiver 8 is connected to a microprocessor 10 which is connected to a clock 12, and which controls the operation of a memory 14 and a data transmitter 16 for recording data on the card. The microprocessor 10 comprises a PIC 16C73.

The data transmitter 16 is a serial data interface and is configured to communicate with the smart card. However alternative types of transmitter are used where the output of the module 2 is recorded by different methods. Thus, for example, if the output is to be relayed along a telephone line to a remote measuring station, the transmitter 16 comprises a modem. Alternatively, the module 2 can have a transmitter which is configured to transmit data over the consumer's power supply lines.

In this example, the components of the module 2 are powered by a battery 18 within the module 2. In an alternative embodiment, a battery is incorporated into the card. It is also possible, in other embodiments, for the module 2 to be powered by a mains power supply or by a battery which is trickle charged with electricity obtained from an inductive link between the module 2 and the meter (which accordingly would include appropriate transmission means).

The memory 14 has 48 addresses, each corresponding to a respective 30 minute period of a day, and a number register for storing the number of the days previously monitored.

The clock 12 enables the microprocessor 10 to identify the beginnings and ends of days and intervals in days.

In use, the module obtains an average profile of daily consumption throughout a charging period, in this case a quarter, in the following way.

During the first day of the quarter, the number register of the memory 14 registers one, and at the beginning of the first 30 minute interval, the microprocessor 10 reads the number of watt hours registered on the meter through the data transmitter 6 and the data receiver 8 and stores that number in the memory 14. At the end of the first 30 minute interval ie at 0:30 hours, the microprocessor 10 reads the number of watt hours registered on the meter, subtracts that number from the previous watt hour reading and stores the difference in one address of the memory 14. The second reading of watt hours is also stored in the memory so that the number of watt hours consumed by the end of the next 30 minute interval (ie at 1:00 hours) can be calculated by the microprocessor and stored in the next address in the memory 14.This process is repeated until a value for the final 30 minute interval, 23:30-0:00 hours, is stored in the 48th address.

The microprocessor 10 then increments the number register of the memory 14 to two, and then calculates the number of watt hours used in each 30 minute interval of the second day. After each interval of the second day has elapsed, the microprocessor 10 reads the value in the address of the memory 14 for the corresponding interval of the previous day and obtains an average for those two intervals, which average is then stored at the same address.

The process is repeated for the subsequent days in the quarter so that at the end of the quarter each value in the memory represents the average number of watt hours consumed in a respective part (for example 12:00-12:30) of the days of the quarter.

These values are then recorded on the card 4 which can then be removed and transferred to a remote processing station at which the users bill for the quarter is calculated.

At the (n+ 1)th day, the microprocessor 10 calculates the average value (at+1) for any given interval in accordance with the following formula: A+1=(X-A) + An n+1 Where X is the number of watt hours measured for the interval just monitored, and An is the average for the corresponding intervals of the previous days. The data recorded onto the card can include information concerning the meter (for example the meter serial number) and various other items of status information.

In this example, the card includes a memory chip connected to conductive tracks on the card's surface which, with the card inserted in the module 2, register with the corresponding pins in the module 2 to enable data to be recorded on the chip on the card.

Claims (17)

1. A method of metering a supply of a commodity to a consumer over a succession of periods, the method comprising the steps of monitoring the consumption of the commodity over a succession of intervals in the first of said periods and storing a plurality of values each related to the amount of commodity consumed in a respective interval; for each subsequent period, monitoring the amount of commodity consumed over a succession of corresponding intervals each interval being is part of a respective set of intervals, in different periods, all the intervals in a given set corresponding to the same respective part of said periods; modifying each value so that it is representative of an average of the amount of commodity consumed in an interval of a respective set; and generating an output representative of said averages.

2. A method according to claim 1, in which each average is a mean average.

3. A method according to claim 2, in which each average is calculated by updating a previously calculated corresponding average value on an ongoing basis as each period is monitored.

4. A method according to claim 3, in which said calculation involves the steps of storing the number of periods previously monitored in a number register, incrementing the register by one when the monitoring of the next period begins; for each interval in said next period, subtracting the respective average value previously calculated from a current value representative of the amount of commodity consumed in said interval of the next period, and dividing the resulting difference by the number in the number register to give a quotient which is then added to said previously calculated average value.

5. A method according to any of the preceding claims, in which the output is transmitted to processing apparatus remote from the location at which said metering occurred, said processing apparatus being arranged to calculate the charge incurred by the use of the commodity.

6. A method according to any of claims 1 to 4, in which the output is stored on a portable card which can be removably accommodated in the apparatus for peforming the metering, and which can be transferred from said apparatus to said processing apparatus at which the data stored on the card is read.

7. A method according to claim 6, in which the method is performed by metering apparatus arranged to accommodate said card, and the power to operate the metering apparatus is provided by a power source mounted on the card.

8. A method according to any of the preceding claims in which the metered commodity is electricity.

9. A method according to any of the preceding claims in which a period comprises one day, and each interval is of 30 minutes duration, so that each period has a total of 48 intervals.

10. Metering apparatus for metering the consumption of a commodity over a succession of periods, the apparatus comprising clock means for determining the beginnings and endings of the periods and, for each period, the beginnings and endings of a succession of intervals spanning said period; monitoring means for monitoring the amount of commodity consumed in each of said intervals; calculating means for calculating the average amounts of commodity consumed per interval for each of a plurality of sets of intervals, all the intervals in each set corresponding to the same respective part of said periods; and memory means for storing a plurality of values, each representative of a respective average.

11. Apparatus according to claim 10, in which the apparatus includes means for receiving a removable card on which said values are recorded.

12. Apparatus according to either claim 10 or claim 11 in which the apparatus comprises a first housing which contains at least part of the monitoring means for measuring the amount of commodity used, and means for transmitting data to a second housing which contains receiving means for receiving said data, said second housing containing said clock means, memory means and calculating means, wherein said first and second housings are separable.

13. Apparatus according to claim 12 in which the transmission means and receiving means comprise an inductive link between the two parts.

14. Apparatus according to any of claims 11, further comprising a removable card on which said values are recorded.

15. Apparatus according to claim 14, in which the card includes a battery for powering said apparatus.

16. A method substantially as described herein with reference to the accompanying drawings.

17. Apparatus substantially as described herein with reference to, and as illustrated in, the accompanying drawings.