GB2595719A

GB2595719A - Smart meter

Info

Publication number: GB2595719A
Application number: GB2008463.8A
Authority: GB
Inventors: Alexander Monty
Original assignee: Yokeru Ltd
Current assignee: Yokeru Ltd
Priority date: 2020-06-05
Filing date: 2020-06-05
Publication date: 2021-12-08
Also published as: GB202008463D0

Abstract

A smart meter comprises a processor to sample an induced current of a power supply to be metered and uses this induced current to self-power the smart meter. A battery 204c may be included to store harvested energy. An inductive charger such as a transformer 200 with a primary winding 201 and a secondary winding 204 is used to power the meter. A further secondary winding 203 may be used for operating point calibration by varying the resistance of one or more windings in the transformer. Another secondary winding 202 is used for current measurement, connected to a diode 202a and resistor 202b acting as the processor. The smart meter may transmit data about power consumption wirelessly to a remote receiver.

Description

SMART METER

Field

The present invention relates to smart meters, and to systems comprising smart meters. The present invention also related to methods of smart metering.

Background

Smart meters are electronic devices that record consumption of electric energy and communicate the information to the electricity supplier for monitoring and billing. Smart meters usually record energy consumption hourly or more frequently and communicate the information at least daily. Communications from the meter to the network may be wireless, or via fixed wire connections.

Present day smart meters require an external power supply which is conventionally provided by hardwiring the device into the mains. This requires an electrician for installation, as fitting a voltage sensor requires interacting directly with the fuse box/communal box. Thus, the cost, inconvenience and complexity of installation of a smart meter increases.

It is an aim of example embodiments to at least partially overcome or avoid one or more disadvantages of the prior art, described above or elsewhere, or to provide an at least partially improved or even an alternative system to those already in existence.

Summary

According to the present invention there is provided an apparatus, a system and a method as set forth in the appended claims. Other features of the invention will be apparent from the dependent claims, and the description which 30 follows.

According to an aspect of the invention, there is provided a smart meter comprising a processor configured to sample an induced current of a power supply, wherein the smart meter is arranged to use the induced current to self-power the smart meter. Thus, the smart meter is easier to install, as the smart meter does not require hardwiring into the mains. Indeed, no electrician is needed for installation.

The smart meter may comprise a battery configured to power the processor, and/or to store power from the induced current. Thus, the smart meter can function, at least in some way (e.g. data sampling, storage, processing, or transmission) even when there is a power outage.

The smart meter may comprise an induction charger configured to charge the battery using the induced current. Thus, the ease of installation of the smart meter is increased, as the smart meter does not require a wired connection in order to receive power.

The smart meter may comprise one or more current transformers. Thus, the smart meter can utilise the one or more current transformers to perform a range of required functions without an increased cost relating to complicated hardware.

The smart meter may comprise a single current transformer comprising one or more windings. Thus, the smart meter can utilise the single current transformer to perform a range of required functions while minimising the size and therefore the invasiveness of the smart meter.

The processor may be operable to utilise one of the one or more windings or the current transformer to obtain a current measurement using a forward induced current and/or a backward induced current. Thus, the smart meter can accurately measure current and use the measured current to record household power usage.

The processor may be operable to utilise one of the one or more windings or the current transformer to perform at least one of: an operating point calibration; an active operating point calibration; or a passive operating point calibration. Thus, error values in the sampled current can be minimised.

The active point operating point calibration may comprise varying a resistance of (which includes relating to, e.g. in connection with) the one or more windings or the current transformer. Thus, error values in the sampled current can be more effectively minimised.

The processor may be operable to utilise one of the one or more windings or the current transformer to perform induction charging using a forward induced current and/or a backward induced current. Thus, the ease of installation of the smart meter is increased, as the smart meter does not require a wired connection in order to receive power.

The processor may comprise a diode to facilitate use of the forward induced current and/or a backward induced current. Thus, current can be sampled in an inexpensive, reliable manner.

The sampling of the induced current, or the use of the induced current to self-power the meter, may comprise one or more of the: obtaining the current measurement using the induced current, and/or performing the operating point calibration, and/or performing the induction charging using the induced current. Thus, the smart meter can perform a wide range of functions, in a relatively simplistic manner.

The smart meter may be arranged to wirelessly transmit a signal indicative of the sampled induced current. Thus, the number of wired connections required by the smart meter to function is reduced.

According to another exemplary embodiment, provided is a system comprising the smart meter and a receiver configured to receive an input from the smart meter, the input relating to the sampling of the current. Thus, the smart meter can communicate readings related to the sampling of the current to a receiver for further processing so that power usage can be determined or recorded.

The receiver may be arranged to use the sampled current to obtain an indication of one or both of power consumption and power usage. Thus, the system can record household power usage, in terms of levels, or patterns or behaviours, as well as identify faulty/anomalous/electrical devices by analysing the sampled current.

The system may further comprise a device for sampling a voltage of the power supply, and the receiver may be arranged to receive an input from the device, the input relating to the sampling of the voltage. Thus, power consumption can be measured using both current and voltage.

According to another exemplary embodiment, provided is a smart metering method, the method comprising sampling an induced current of a power supply, wherein the induced current is used to self-power the sampling. Thus, the sampling can be self-powered, thereby eliminating the need for hard wiring a smart meter to an inlet power cable.

Introduction to drawings

For a better understanding of the invention, and to show how embodiments of the same may be carried into effect, reference will now be made, by way of 25 example only, to the accompanying diagrammatic drawings in which: Fig. 1 schematically depicts a smart meter according to an example embodiment; Fig. 2 schematically depicts a current transformer according to an example embodiment; Fig. 3 schematically depicts a system according to an example embodiment; Fig. 4 depicts steps in a method according to an example embodiment.

Description of example embodiments

Referring now to Figure 1, a smart meter is denoted as a whole by the reference numeral 100.

Smart meters such as the smart meter 100 require power to operate. Typically, in the prior art, a smart meter is hard wired to an inlet power supply. This process is complicated and risky, and so requires assistance from an electrician. This is because fitting the smart meter typically requires interacting directly with a fuse box/communal box, and/or significant sources of electricity.

Thus, the cost of installation of a smart meter increases. Another solution for powering a smart meter includes the use of batteries. A disadvantage of such an approach is the fact that batteries usually do not last very long, and thus require frequent replacement. Without replacement, the smart metering may fail, or be unreliable. Alternatively, a separate power cable can also be used to power a smart meter. However, often there are no plug sockets located close to the fuse box, or general location of the smart meter. Furthermore, such approach is invasive due to presence of additional cabling.

Referring to the present invention, the smart meter 100 comprises a processor 101 configured to sample an induced current of a power supply, and use the induced current to self-power the smart meter 100. The power supply may be an external power supply such as an inlet power supply of a house. By using the induced current to self-power itself, the smart meter 100 addresses the above-described issues, as it is easier and cheaper to install than, for example, hard wiring the smart meter to the inlet cable, while reducing the amount of additional cabling required. Thus, the invasiveness of the smart meter is reduced as hard wiring a smart meter intrudes in the home space of an individual.

The smart meter may be located proximal to the power supply. The smart meter may sit adjacent to the power supply, for example alongside a wire or cable. This might include the power supply being somehow fixed to the supply, for example by way of a clip, clasp, clamp or other fixing element. The fixing element is typically selectably in a fixed or released state, to allow for easy fixing and unfixing by a user.

The processor 101 can be a microcontroller, a microprocessor, a central processing unit, or any other circuitry suitable for controlling an operation of an electronic device such as the smart meter 100.

The smart meter 100 further comprises a battery 102 configured to power the processor 101 and/or to store power from the induced current. Storing power from the induced current ensures that the processor 101 can function without interruptions in case of a blackout or a power supply fault. Thus, the operation of the smart meter 100 is more reliable. The smart meter 100 further comprises an induction charger 103 configured to charge the battery using the induced current, enabling the battery 102 to store power. The induction charger 103 might alternatively or additionally directly power the processor 101.

The induction charger 103 comprises one or more current transformers 104, or a single current transformer 104 comprising one or more windings. The use of one or more current transformers offers the advantage of reduced cost, when compared to using a single transformer comprising one or more windings, as manufacturing a single transformer comprising multiple windings is more expensive. However, it is inefficient and larger in size than a single transformer comprising one or more windings.

In the example of Figure 2, a single current transformer 200 comprising one or more windings is depicted. The single current transformer 200 can be equated to the single current transformer 104 of Figure 1.

In the particular example of Figure 2, a single current transformer 200 comprises four windings -a primary winding 201, a first secondary winding 202, a second secondary winding 203, and a third secondary winding 204. The windings of the current transformer 200 share a single common core. The primary winding 201 comprises 1N turns. The first secondary winding 202 and the third secondary winding 204 comprise 2N turns. The second secondary winding 203 comprises 1M turns.

The primary winding 201 draws power from the power source, e.g. an inlet power supply of a house. When an input voltage is applied to the primary winding 201, alternating current starts to flow in the primary winding 201. In the UK, the electric power supply has a voltage of 230V and a frequency of 50Hz. As the current flows, a changing magnetic field is set up in a core of the current transformer 200. As this magnetic field cuts across the remaining windings, alternating voltage is produced therein.

Referring to the example of Figure 2, the function of the first secondary winding 202 is to enable the processor 101 to obtain a current measurement using a forward induced current. However, the skilled person would appreciate that the current measurement could be obtained using at least one of the forward induced current and backward induced current. In the example of Figure 2, the first secondary winding 202 is part of a circuit comprising a diode 202a and a resistor 202b, and this forms part of the overall processor 101 (i.e. the processor is not necessarily just a chip or CPU), but a skilled person would appreciate that any other arrangement of electrical components suitable for sampling a current could be used. Use of a diode, however, is a simple and effective way of facilitating selective monitoring or processing of forward or backward induced current -e.g. by use of appropriate diodes in particular configurations, for different windings.

The processor 101 utilises the first secondary winding 202 to obtain the current measurement using the induced current, via the components discussed above. Obtaining the current measurement comprises sampling the induced current. However, only the current measurement can be accurately measured using induction. Thus, in another embodiment, the processor 101 is configured to utilise a voltage transducer in order to obtain a voltage measurement.

The processor 101 is operable to use the sampled current to collect data readings relating to power, voltage and/or current. The smart meter 100 is configured to wirelessly transmit a signal indicative of the sampled induced current (i.e. the collected data readings) to a receiver. Such receiver may be, for example, a server of an electricity supplier, optionally via a router in the home or workplace of a user.

The signal indicative of the sampled induced current is used to record household power usage, as well as to monitor an individual's routine by classifying appliance type. When an appliance is powered on, a higher current passes through the communal box. A proportional current (and therefore voltage) can be collected. In addition, the signal indicative of the sampled induced current may also be used to identify faulty/hazardous electrical devices by identifying anomalies in power draw. Thus, the smart meter 100 collects accurate, actionable information, enabling monitoring for a whole range of users and application. This might include monitoring for power usage, for the benefit of a user or a supplier, but could also extend to vulnerable people (such as the elderly). The information can be used to provide an individual risk register to proactively support vulnerable people by monitoring their wellbeing, for example via the identification of particular patterns of behaviour. The pattern might reflect a problem, or the absence of a problem.

The second secondary winding 203 enables the processor 101 to perform at least one of: an operating point calibration; an active operating point calibration; or a passive operating point calibration. Calibrating the operating point reduces error values in the sampled induced current. These error values occur due to power destabilisation caused by hysteresis. Over time, residual magnetism can be found in the core of the current transformer 200, causing a loss of efficiency by impacting the amount of energy transferred through inductive coupling. Calibrating the operating point balances the magnetisation (B-H) curve by moving it towards the origin. That is, the second secondary winding 203 dissipates residual flux by improving gain.

In the example of Figure 2, the second secondary winding 203 is part of a circuit comprising a resistor 203b and a capacitor 203a. Resistance of said circuit is used for operating point calibration in an operation called passive operating point calibration. Active operating point calibration is achieved by varying a resistance of the second secondary winding 203. Active operating point calibration can be achieved by, for example, replacing the resistor 203b with a variable resistor. In a preferred embodiment, the time constant RC of the circuit is large such that the V-s imbalance between the windings of the current transformer 200 can be integrated.

The third secondary winding 204 enables the processor to perform induction charging using the backward induced current. However, the skilled person would appreciate that induction charging could also be obtained using the forward induced current, or both forward and backward inducing current. In the example of Figure 2, the third secondary winding 204 is part of a circuit comprising a diode 204a and a resistor 204b, as well as a power supply unit 204c. Referring back to Figure 1, the power supply unit 204c can be, for example, the battery 102. In order to output DC voltage for powering the smart meter 100, the third secondary winding typically comprises or is in connection with an AC-DC converter, such as a full-wave rectifier.

Figure 3 describes a system 300 comprising a smart meter 301 and a receiver 302, configured to receive an input from the smart meter 301, relating to the sampling of the current. The smart meter 301 is identical to the smart meter 100 depicted in Figure 1. The smart meter 301 is configured to transmit an input relating to the sampling of the current to the receiver 302. The smart meter 301 may be in bidirectional communication with the receiver 302; that is, the smart meter 301 can receive inputs from the receiver 302. The receiver 302 may be a hub or central managing or processing device, and/or, for example be, include or be in connection with, an external server, a router, or a gateway. The input related to the sampling of the current may be, for example, a current measurement, a voltage measurement, a power measurement, or the like.

The receiver 302 could receive other inputs, for example from a device for sampling a voltage of the/a power supply. This could be, and might be conveniently be, located separate to and remote from the smart meter 301. For example, the device might be easily located in a socket of a power supply system of a house or building, where voltage can easily be sampled. That is, the smart meter can sample current without being wired in to the supply, and the voltage can be separately sampled, and for example wirelessly communicated to the receiver. Or, the receiver could actually be or include the voltage sampling device. This reduced complexity makes system installation easier, and less intrusive, for much the same reasons as discussed above.

The use of current and voltage sampling might allow for a more accurate reading of power usage.

Figure 4 describes a smart metering method using a smart meter, such as that described above. The method comprises sampling an induced current of a power supply S100, wherein the induced current is used to self-power the sampling. The method may comprise transmitting a signal indicative of the sampled induced current. The method may also comprise calibrating the sampled induced current to reduce errors in the sample.

In summary, the present invention provides a simple but effective smart meter, that is simple to install and use.

Attention is directed to all papers and documents which were filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalents or similar features.

The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

Claims 1 A smart meter comprising a processor configured to sample an induced current of a power supply, wherein the smart meter is arranged to use the induced current to self-power the smart meter.
2. The smart meter of claim 1, further comprising a battery configured to power the processor, and/or to store power from the induced current.
3. The smart meter of claim 2, further comprising an induction charger configured to charge the battery using the induced current.
4. The smart meter of claim 3, wherein the induction charger comprises one or more current transformers; or a single current transformer comprising one or more windings.
5. The smart meter of any claim 4, wherein the processor is operable to utilise one of the one or more windings or the current transformer to obtain a current measurement using a forward induced current and/or a backward induced current.
6 The smart meter of any one of claims 4 to 5, wherein the processor is operable to utilise one of the one or more windings or the current transformer to perform at least one of: an operating point calibration; an active operating point calibration; or a passive operating point calibration.
7. The smart meter of claim 6, wherein the active operating point calibration comprises varying a resistance of one of the one or more windings or the current transformer.
8 The smart meter of any one of claims 4 to 7, wherein the processor is operable to utilise one of the one or more windings or the current transformer to perform induction charging using a forward induced current and/or a backward induced current.
9. The smart meter of any one of claims 5 to 8, wherein the processor comprises a diode to facilitate use of the forward induced current and/or a backward induced current.
10. The smart meter of any of claims 5 to 9, wherein the sampling of the induced current, or the use of the induced current to self-power the smart meter, comprises one or more of the: obtaining the current measurement using the induced current, and/or performing the operating point calibration; and/or performing the induction charging using the induced current.
11. The smart meter of any of claims 7 to 10, wherein the smart meter is arranged to wirelessly transmit a signal indicative of the sampled induced current.
12.A system comprising: the smart meter of any preceding claim; and a receiver configured to receive an input from the smart meter, relating to the sampling of the current.
13. The system of claim 12, wherein the receiver is arranged to use the sampled current to obtain an indication of one or both of: power consumption; power usage.
14. The system of claim 12 or 13, further comprising a device for sampling a voltage of the power supply, the receiver being arranged to receive an input from the device, relating to the sampling of the voltage.
15.A smart metering method, comprising: sampling an induced current of a power supply, wherein the induced current is used to self-power the sampling.