GB2588799A - Power loss detection in a network - Google Patents

Abstract

Non-technical power loss or theft of electricity at a point 16 in an electrical network 18 is detected by: measurement of current through the live 24 and neutral 26 lines; analysing the overall harmonic activity in each live phase; calculating the total harmonic content of the current in each live phase and the neutral; calculating the theoretical neutral current taking account of the calculated total harmonic content; and analysing the difference between the theoretical neutral current and the measured neutral current to provide a power theft indicator. The current measurements may be made in a meter test set 12 located in situ on-site. Measurements are transmitted from the test set 12 to a smart device 14 for analysis. The smart device has a display 22 for indicating parameters of the measured phases and indicating theft. Smart device 14 may also communicate with a remote or cloud server 34 for further data analysis.

Description

Intellectual Property Office RTM Date:1 May 2020 Application No. GB1916225.4 The following terms are registered trade marks and should be read as such wherever they occur in this document: WiFi Direct Intellectual Property Office is an operating name of the Patent Office www.gov.uk/ipo

POWER LOSS DETECTION IN A NETWORK

The present invention relates to a portable electrical power loss detector. More particularly, the present invention relates to a portable electrical power loss detector for identification of the location of the power theft and the quantification of non-technical power losses. The present invention further provides a portable device for the analysis of the electricity supply quality.

BACKGROUND OF THE INVENTION

The generation, transmission and dMflbUIOfl oeiecitri S many g'aticinai iii.)ssias, which can be catiagorised s Technicai iosses ci Non-technicai icases. Overall technical losses occur naturally and are typically result from power dissipation in transmission lines, transformers, and other power system components. By contrast, Nontechnical losses may relate to energy theft, or tampering.

The theft of electricity is the criminal practice of stealing electrical power and involves the tampering with a meter or its connections.

Figure 1A shows a normal single-phase arrangement at an electrical meter. Often where energy theft occurs, meters are tampered with as shown in the arrangements of Figures 1B to 1D where the earth is being utilized as a pseudo neutral.

After such tampering, the meter no longer accurately records how much electricity is being used. Electricity theft increases costs for customers as well as presenting significant safety concerns due to the serious risks associated with interfering with electricity meters or cables. To protect customers from inflated costs due to electricity theft, energy regulators require that energy supply companies play an active role in the detection, investigation and prevention of the theft of electricity.

There are several conventional methods of theft detection which typically operate using a 25 combination of metering value comparisons (including billing data), electricity meter test sets, customer profile monitoring and manual checking by trained meter readers and auditors.

For example, the standard method of measuring power theft is by analysis of transmission and distribution losses (T&D losses). This method of detection takes the difference between the amount of electricity generated (minus system use and gratis) in relationship to the amount of electricity metered and sold. If an accurate calculation is made of the technical losses, theft may compose a large part of the unaccounted amount i.e. the non-technical line losses in the distribution network. Non-Technical Losses (NTL) during electrical energy transmission is a global problem that is particularly significant in developing countries.

However, assessing metered energy flow in the main feeder and comparing to metered energy flow at metered distribution points within the subsequent network to detect any 5 energy loss as theft requires the assumption that all meters are accurately reporting the energy flow, that harmonics are irrelevant and that technical losses can be accurately evaluated, even with real time load variability. Further, fast switching modern electronic equipment such as Uninterruptable Power Supply (UPS) devices and rectification devices cause significant 'pollution' in the supply. Neglecting this supply pollution and the associated 10 harmonic content problems could potentially mask electricity energy theft.

The use of in-situ electricity meter testing sets focuses on checking the accuracy of a meter, the wiring to the meter and the supply quality functions. However, they do not significantly measure the neutral current and cannot, for example, determine a bypass of a meter or an open neutral of a meter, both of which are common electricity theft methods. Specifically, they do not analyse the form of the supply and neutral currents in either the single or three phase configurations to determine the difference between actual energy theft and the effects of harmonics from attached equipment.

Customer profile monitoring can be carried out automatically using specifically designed software to detect changes in the consumer profile and power usage. However, if the electricity theft has been occurring from the outset and/or the electricity theft is gradually introduced over time, the electricity theft may go undetected as no significant customer profile change would be identified and flagged up.

Non-engineering approaches often involve manual reading of meters by meter readers. Although this provides useful (and ideally accurate) information, it is vulnerable to exploitation by individual meter readers being tempted into electricity theft collaboration, particularly in developing countries where salaries and relatively low and electricity costs are proportionately high.

As much electricity theft involves bypasses or open neutrals, which can be well-hidden and potentially reversed where a manual inspection becomes imminent, means that historic data is often inadequate. Thus, a more dynamic solution with real-time values would provide valuable information to electricity theft inspectors as well as being more effective at identifying electricity theft even when bypasses or open neutrals are removed and/or potentially reversed in-situ.

Often, conventional electricity theft detection requires an initial indication of theft, for example via direct reporting from another consumer or using billing analytics to detect customer profile variations. Once a potential electricity theft suspect is identified, on-site inspection can be carried out to take direct meter readings etc. There is therefore a need for an improved electrical power loss detector. Ideally, there is a need for an improved electrical power loss detector that can both detect and quantify electricity theft at a consumer location, even in the presence of electrical supply pollution.

SUMMARY OF THE INVENTION

The present invention seeks to address the problems of the prior art.

According to an aspect of the present invention, there is provided a method for the detection of non-technical power loss at a selected point in an electrical network, the method comprising the steps of: on-site measurement of current through the live and neutral lines at the selected point in the electrical network; analysing the overall harmonic activity in each live phase in dependence upon the measured current through each live line; calculating the total harmonic content of the current in each live phase and the neutral in dependence upon the overall current in each live phase and the neutral; calculating the theoretical neutral current in dependence upon the calculated total harmonic content of the current in each phase and the neutral; and analysing the difference between the theoretical complex neutral current and the measured complex current through the neutral line at the selected point in the electrical network to provide a power theft indicator.

The present invention analyses both the live and neutral line dynamic parameters. Please note that this may be in either single or three phase star (wye) connected systems. The present invention provides a detailed harmonic analysis to give the calculated total harmonic content of the current in each phase and the neutral. This harmonic analysis is then used in a mathematical comparison of measured and calculated neutral currents and determines whether power theft has occurred. Potentially, the scale of any detected power theft can also be assessed.

In one embodiment, a difference between the theoretical neutral current and the measured neutral current is indicative of power theft.

In a further embodiment, the difference between the theoretical neutral current and the measured neutral current is indicative of the level of power theft.

Preferably, Discrete Fourier Transform or Fast Fourier Transform is used for analysing the overall harmonic activity in each live phase. However, it is to be appreciated that the analysis of the overall harmonic activity in each live phase may be done by any version of the Fourier Transform or other transform that can describe the complex measured waveforms in terms of sinusoidal components.

A second aspect of the present invention provides an apparatus for the detection of nontechnical power loss at one or more selected points in an electrical network, the system comprising: one or more test sets, each test set comprising a current measuring circuit operable for electrical engagement with the live and neutral lines at the selected point in the electrical network, wherein the test set is operable to transmit measured data from the test set; and one or more portable smart devices, each portable smart device configured for wireless communication with a respective test set when located within wireless communication distance of the respective test set and operable to receive measured data from the test set and carry out the method of according to a first aspect of the present invention.

Each test set may include an anti-aliasing filter to mitigate the problem of high frequency harmonics appearing to be lower frequency harmonics and thus distorting the results.

In one embodiment, each test set remains in situ over time at the selected point in the electrical network and each of the one or more portable smart device is moveable between 20 test set locations within the electrical network.

Thus, one mobile (or portable) smart device may be used by an operator at many different selected points in an electrical network to harvest data from a plurality of test sets, each selected point in the electrical network having a test set located in situ.

Interference with the monitoring device in situ is mitigated through a physical separation of 25 the operator interface i.e. at the smart device, from the sealed measuring device i.e. the test set. However, the two components i.e. test set and smart device, are in wireless communication, thereby creating a virtual system.

As the measurement operation is undertaken at a sealed test set located in situ and is physically separated from the smart device which undertakes the data request command, 30 control of received data, and analysis functions, the possibility of interference by non-utility staff is minimised.

In addition, as the smart device will preferably be in communication with a server via the internet, data can be immediately uploaded into an online database and analytics engine. This internet capability may be wired or wireless and need not be invoked in order for analysis to be undertaken locally by the smart device. However, the capability of instant upload of measured and analysed data further mitigates the opportunity for operator interference with collected data and analysis results.

In a further embodiment, each smart device further comprises a display for displaying one or more of the following for each test set it wirelessly communicates with: measured current through the live and neutral lines at a selected test point in the electrical network, the calculated Total Harmonic Distortion value for that test point, the power theft indicator for that test point, the level of power theft at the test point and identification data relating to the location of the test point within the electrical network.

The smart device may be operable to transmit all measured and/or calculated data to a remote server for further analysis.

Analysis at the secondary level i.e. at the online database level, would allow further profiling, audit and other statistical analysis showing trends, cross-site comparisons and various types of anomalies, both in the short term and over longer monitored time periods. Thus, it is to be appreciated that the apparatus in accordance with the second aspect of the present invention can operate to localise electrical energy theft problems using geographically diverse data and may then potentially define and quantify those theft issues, despite the present of noise pollution using the detailed analysis of phase and neutral currents.

A third aspect of the present invention provides a system for the detection of non-technical power loss in an electrical network, the system comprising: one or more test sets, each test set comprising a current measuring circuit operable for electrical engagement with the live and neutral lines at a selected point in the electrical network, wherein each test set is operable to transmit measured data from the test set; one or more portable smart devices, each portable smart device configured for wireless communication with a respective test set when located within wireless communication distance of the respective test set and operable to receive measured data from the test set and carry out the method in accordance with a first aspect of the present invention; and a remote server in wireless communication with the one or more portable smart devices and operable to receive data from each smart device for aggregation of data from multiple points in the electrical network and synchronisation of data to further evaluate power quality and theft in the electrical network.

In one embodiment, each test set remains in situ over time at the selected point in the electrical network and each of the one or more portable smart device is moveable between test set locations within the electrical network.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1A is a diagrammatic representation of a normal single-phase arrangement; Figures 1B, 1C and 1D are diagrammatic representations of alternative arrangements where earth is used as a pseudo neutral in the single-phase arrangement of figure 1; Figure 2 shows a Three Phase Star! Wye arrangement; Figure 3 shows a Three phase balanced load waveform; Figure 4 shows a Three phase balanced load vector diagram; Figure 5 shows voltages in a balanced wye circuit; figure 6 shows voltage and current phasors for a balanced resistive wye load Figure 7 shows voltage and current phasors for an unbalanced wye circuit figure 8 is a circuit diagram showing that in a balanced three-phase load, the neutral current is zero; Figure 9 is a circuit diagram showing that where there is an unbalanced load, the neutral current is not zero, but is smaller than the phase current; Figure 10 is a circuit diagram showing that where there is a non-linear three-phase 20 load, the neutral current is not zero and is potentially larger than the phase current because of homopolar harmonics Figure 11 is a diagrammatic representation of third harmonic currents in the neutral conductor; Figure 12 shows a block diagram of a conventional three-phase electricity meter test set; Figure 13 shows an embodiment of a system for the detection and quantification of non-technical power loss in an electrical network in accordance with a third aspect of the present invention; Figure 14 shows a user interface of a test set of an embodiment of an apparatus in 5 accordance with a second aspect of the present invention; Figure 15 is a diagrammatic representation of a system for the detection of nontechnical power-loss in an electrical network, in accordance with the present invention; and Figure 16 is a flow diagram illustrating an embodiment of a method for the detection of non-technical power loss at a selected point in an electrical network in accordance with an 10 aspect of the present invention, using the apparatus of figure 14.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Single Phase System In a basic single phase (Live & Neutral) system, under ideal conditions, there is a balance between the current flowing in the live conductor and that in the neutral conductor. In practice there may be a discrepancy due to "earth leakage", but these are usually small and such discrepancies would not indicate any power theft.

However, there are a number of scenarios that could cause an imbalance between the current measured in the live and neutral conductor due to theft by using an "earth" conductor as a pseudo neutral, for example, as discussed above in relation to figures 1B to 1D.

Three Phase In a star (wye) connected three-phase system, the current in the neutral conductor is the vector sum of the three line currents.

Balanced three phase system: With a balanced sinusoidal three-phase system of currents, this sum is zero at any point in 25 time and the neutral current is therefore zero (see figure 8).

Thus, in a balanced three phase system, with a sinusoidal supply and each phase having a 120° difference, then the neutral current will be zero. Figures 2 to 4 show facets of this scenario.

The line and phase voltages could be different in magnitude and phase, depending on the load and currents in each phase. These currents can be both calculated using standard vector analysis and practically measured using current transformers and an appropriate instrument. Figure 5 shows for the voltages in a balanced wye circuit and figure 6 shows voltage and current phasors for a balanced resistive wye load.

By noting that the current phasors above are separate by 120 degrees and all of the same magnitude, then by taking cos(60) = 0.5, the current flowing into the neutral line can be shown to be zero.

Unbalanced three-phase system: However, this is not the case for an unbalanced load, as can be seen in figure 7 which shows a phasor diagram for an unbalanced wye circuit, as the magnitudes of each phase current are not equal.

Thus, in a three-phase power system feeding linear single-phase loads the current in the neutral conductor is rarely zero because the load on each phase is different. Typically, the 15 difference is small and is in any case far lower than the line currents (see figure 9).

An appreciation of this, together with the measured supply currents, allows the theoretical neutral current to be calculated and compared to the neutral current measured. This gives an indication of a difference between theoretical and actual neutral currents and, in theory, this can be used as an indicator of power theft.

Modern Situations -non-sinusoidal currents Although the above approach works well for unbalanced, sinusoidal arrangements, it neglects the issues introduced by modern power electronic devices and systems, such as rectifiers and switched mode power supplies.

These devices "pollute" the normal sinusoidal waveforms by introducing harmonics which 25 can significantly alter the neutral current.

High neutral currents normally result from two situations. The first, and most common, is one where there are simply heavily unbalanced loads. This situation is usually easy to analyse, explain and remedy: loads need to be evenly distributed across the phases to reduce the neutral current.

Where non-linear loads are being supplied, even when the load is well balanced across the phases, there is likely to be substantial current in the neutral conductor. With non-sinusoidal currents, the sum of the three line currents, even with the same rms value, may be different from zero. For example, currents with equal Root Mean Square (RMS) values and square shape will result in a significant neutral current (see figure 10).

In a heavy harmonic environment, whilst positive and negative sequence components of 5 harmonic currents cancel at the neutral point, zero sequence harmonics do not. The zero sequence components are additive at the neutral and are the reason for high neutral current, even though the loads may be perfectly balanced.

In fact, the third harmonic components (and all other harmonics where the order is a multiple of three -the sixth, ninth, etc.) of the line currents are all in phase with each other (i.e. they 10 are homopolar components), so they sum arithmetically rather than cancelling by vector addition (see Figure 11).

The neutral current amplitude may exceed the phase current in amplitude at the supply frequency due to the third harmonic.

Excessive neutral current usually results in high power losses in distribution transformers, but are not in themselves an indicator of power theft. However, they can mask power theft as there would be the ability to draw more current from the supply phases and not return the current through the neutral whilst still making the system appear to be under normal conditions.

This situation means that, in order to be able to compare actual and theoretical neutral currents, calculation of the total harmonic content of the phase currents needs to be undertaken from the measured values in real time. Once these values have been measured, the harmonic content can be calculated through a form of Fourier analysis and the zero, positive and negative sequence components established.

This also provides the data to calculate a figure for Total Harmonic Distortion (THD).

The actual neutral current at any point in time can then be mathematically constructed through vector analysis and compared to the actual neutral current content in terms of magnitude and phase at each of the harmonics under consideration.

Discrepancies between calculated and actual neutral currents can then be made and both an indication and estimation of power theft made over a period of time.

Conventional three-phase electricity meter test set A conventional three-phase electricity meter test set normally comprises of three current and voltage measuring circuits. The readings obtained from these circuits can be used to identify a range of important parameters including voltage, current, power and power factor. This 5 arrangement is shown in figure 12.

The traditional meter test set consists of 3 voltage measuring circuits, three current measuring circuits, a processor, a display, a keypad / switch / push button / controller memory, a power supply, a communications port such as RS232 etc. a scanning head for counting pulses and current clamps (probes) for engagement with the circuits being measured.

Apparatus of the present invention An embodiment of the apparatus in accordance with an aspect of the present invention is shown in figure 13 and described further in figures 14 to 16. Apparatus 10 comprises a meter test set 12 and smart device 14.

Meter test set 12 includes embedded software, such that on a single-phase meter one of the current inputs can be used to measure neutral and that the neutral current is measured and compared to that of one of the current inputs measuring the positive current.

For three phase meters, such as shown in figure 13, a 4th current measuring circuit is included in meter test set 12 for neutral measurement, so that all 3 positive lines can be 20 compared with the neutral line.

Meter test-set 12 is located in situ in electrical communication with a selected point 16 in an electrical network 18. The measurement process is digital in nature and discrete samples of the measured value are taken at regular time periods. This time period is chosen in relation to the maximum harmonic value of interest.

A filter may be used to minimise higher frequency values. This prevents the effect known as aliasing and the filter is known as an anti-aliasing filter. Such a filter has software settable parameters so that the filter is automatically and intelligently set with the correct cut-off frequency in relation to both the highest harmonic of interest and the sampling period. The filter is included to increase the rigour of the measurement system and to mitigate the problem of high frequency harmonics appearing to be lower frequency harmonics and thus distorting the results.

Meter test set 12 does not require a display, as meter test set 12 is located in situ to facilitate ongoing measurements at regular time periods and is not intended for direct viewing by an operator for the purposes of collecting measured data. In fact, often meters (and thus meter test sets 12) are located in difficult to access spaces and so it is beneficial that direct access to the meter and meter test set 12 are not required in order to obtain measured data. Instead, measured data can be transmitted to nearby smart device 14 which is operated by an authorised user. The data may be transmitted wirelessly when the smart device 14 is within transmission distance of the meter test set 12 and the data may be transmitted automatically or on receipt of an interrogation request transmitted from the smart device 14 to the meter test set 12 on operation by a user. It is to be appreciated that the smart device 14 may be in wired communication with the meter test set 12 where the meter test set 12 is readily accessible to the user.

Smart device 14 is operable to receive the transmitted date from the meter test set 12 and is provided with a controller which then analyses the data and provides an output to a user via an integral user interface 20. User interface 20 includes a display for displaying measured information and analysis results for viewing by a user. An example of the information displayed is shown in figure 14. The analysis results also provide the user with an indication of whether non-technical power loss has been detected at the selected point in the electrical network 18.

Thus, the data collection and analysis of measured data takes place at the smart device 14, rather than at the meter test set 12, as would be the case in conventional systems. As Smart device 14 has a powerful memory and processing power it is possible to have the analysis undertaken at the meter test set 12, but the preferred embodiment is that the analysis be undertaken on the Smart device 14, as software maintenance, upgrades and client specific modifications can be more easily implemented, even Over The Air (OTA), whilst maintaining a standardised implementation of the measuring device 12. The provision of a user interface 20 with display 22 which is more user friendly than a conventional test-set keypad and display arrangement.

A further advantage of having the meter test set 12 and smart device 14 as separate function is that control of the meter test set 12 by the smart device 14, and the viewing of the measured and analysed data by a user can take place at a distance from the selected point 16 of the electrical network 18, thereby overcoming any safety issues with accessing the selected point 16.

It is common for electricity metering points to be in awkward positions such as cupboards; panel boxes etc. and where viewing and controlling a traditional test set with a display can be awkward. Thus, the present apparatus also serves to improve the comfort of the user who is not having to access these awkward to reach areas.

The remote nature of the smart device 14 communicating with the meter test set 12 via a standard communication package such as Bluetooth® provides an improvement in safety, comfort and anonymity. For example, a user need not seek the permission or cooperation of a home occupier in order to access measured data from the meter test set 12. This has the additional advantage that the home occupier need not be alerted to the collection of data from the meter test set 12 and therefore has no prior warning of data collection and thus warning to correct any tampering at the meter to remove evidence that power theft has been taking place.

Instead, the user may collect measured data from the meter test set 12 and observe measured and analysed data on the display 22 of the smart device 14 and observe whether 15 power theft is occurring in real time.

Another her key advantage is that the smart device 14 is internet enabled and therefore a ready-made Internet connection exists from the meter test set 12 via the smart device 14 allowing data to be updated to a server. This allows multiple users to view the live results via independent smart devices. This provides a mobile and flexible platform where real time (live) data such as power, energy, voltages, currents and phase angles etc. can be monitored and viewed not only in a control room but locally via smart devices such as tablets. A simple comparison between energy delivered and that monitored through numerous meter test sets in an electrical network will provide an immediate indication of non-technical power losses, both in numeric and percentage values.

A further option is to provide an internet communication module in the meter test set 12 so that it becomes a web-based data logger for longer term monitoring and supervision via a web-based server. The very dynamic nature of energy theft, where bypasses etc. can be removed at the first sight of a utility engineer means that longer term data logging and numerical and graphical comparisons of multiple metering points can not only provide evidence of energy theft! tampering but also be a useful tool in locating theft! tamper events. The data logger function is also a useful tool for general energy management where savings in energy usage can be determined by monitoring the energy profile of a consumer. Further, this more dynamic solution with live values would provide valuable tools and techniques to those carrying out energy theft detection. By using the meter test set as an internet enabled data logger, a portable smart monitoring / audit system becomes available for metering points with no Automatic Meter Reading (AMR) or smart metering.

Method of the present invention As in a balanced load where the three phases balance out in the neutral, the neutral line would theoretically have no current. In practice, systems rarely have perfectly balanced loads, currents, voltages and impedances in all three phases. The analysis of unbalanced cases is greatly simplified by the use of the techniques of symmetrical components. An unbalanced system is analysed as the superposition of three balanced systems, each with the positive, negative or zero sequence of balanced voltages.

The neutral current can be determined by adding the three phase currents together as complex numbers and then converting from rectangular to polar co-ordinates. If the three phase Root Mean Square (RMS) currents are 1L1' I12 and 113, then the neutral RMS current is: 1L1 + 1L2 * cos 2/3 u + j * IL2 * sin 2/3 7 + IL3 * cos 4/3 U + J * 1L3 * sin 4/3 7 (where represents the standard}operator' used in convention engineering mathematics) Through calculation a comparison can be made between calculated neutral current and measured neutral current, and any significant difference would indicate a possible tamper condition.

In order to trace a metering point suspected of being tampered, comparisons can be made between energy delivered and that recorded. These results can become far more meaningful if comparable values can be acquired and correlated over multiple metering points. Due to the dynamic nature of energy theft, ideally this should be live data as opposed historical data.

Traditional test sets can be both cumbersome and costly due to the need for each to have controls and display. However, significant improvements can be made if these components 25 are replaced by a wireless communication module that facilitates data connectivity to a remote smart device (tablet, phone etc.).

This allows for a high integrity "anonymous" measuring system that communicates with a command and control app on a smart device.

These features can be enhanced, modified and re-configured to provide a multitude of 30 display, command and control features to suit a variety of utility and jurisdictional needs.

The software on the Smart device can be configured to also automatically and in real time, deliver the results of the calculations made on the Smart device to an Internet based repository for long term storage, audit trail and analytical purposes.

This process is equally applicable to single and three phase wye (star) arrangements as the 5 comparison of actual and calculated neutral currents is a common feature.

An embodiment of a system for the detection and potential quantification of non-technical power loss in an electrical network in accordance with a third aspect of the present invention is shown in figure 15.

Device costs, safety, integrity and ease of use are consequently improved due to the fact that the display and control functions are now virtual software elements that exist separately to the measurement device but still remain functionally attached through a communications protocol. The processing capability, user interface (GUI) and control functions of the test system therefore become enhanced as they can be adapted and updated for different types of user and can potentially work across many different hardware platforms. The ability to display live data via the internet, which can be viewed on multiple test sets and smart devices at different locations, allows a significantly improved and pro-active approach to energy theft. This data would include power values as well as voltages, currents, vector diagrams, harmonic content and time stamped energy loses.

An embodiment of a method for the detection of non-technical power loss at a selected point 20 in an electrical network in accordance with the present invention will now be described with reference to figures 15 and 16.

A meter test set 12 is positioned at a selected point of interest 16 in an electrical network 18, for example at a domestic or industrial electrical meter. The meter test set 12 is electrically connected to the electrical network 18 such that current is measurable through the three positive 24 lines and one neutral line 26 (see step A of figure 16). It is to be appreciated that other useful data may also be collected for onward analysis.

Once connected, the meter test 12 may continuously collect data relating to the current through the three live lines 24 and one neutral line 26 or may sporadically collect data on a timed basis or, alternatively, may collect data on receipt of a demand signal from a remote 30 smart device 14 (see step C of figure 16).

Once collected, the measured data is retained at the meter test set 12 until transmission via transmitter-receiver 28 to a nearby smart meter 14 via wired or wireless communication.

Smart device 14 comprises a device such as a mobile handset. Smart device 14 is provided with a user interface 20 such as a Graphic User Interface (GUI) with a visual display 22.

Smart device 14 is further provided with a controller 32 in communication with the transmitter-receiver 30 and operable to receive and analyse measured data received from the meter test set 12 via transmitter-receiver 30 of smart device 14.

In the embodiment of figures 35 and 16, smart device 14 includes a transmitter-receiver 30 which is configured for wireless communication with meter test set 12 via Bluetoothe communication protocols. However it is to be appreciated that any other suitable wireless communication protocol could be used as an alternative to BluetoothC), for example, but not limited to, Ultra VVideband (UWB), Induction wireless, VVifi Direct or the like.

Measured data collected at the selected point 16 in the electrical network 18 is transmitted from the transmitter-receiver 28 of meter test set 12 to the transmitter-receiver 30 of smart device 14 (see step D of figure 16). Once measured data has been transmitted from the meter test set 12 to the smart device 14, the measured data is deleted from the meter test set 12. The test set 12 has a capability for the storage of measured data in the short term to overcome occasional issues of corrupted or interrupted data transfer and to allow retransmission as necessary. The actual length of the short term storage is solely a matter of cost and not technical capability. Typically several hours of the most recent data would be stored as a standard approach but this could easily be increased to several days worth of data should the need ever arise. The data would be stored in a Last In -First Out memory buffer.

On receipt of the measured data by the transmitter-receiver 30 of smart device 14, the measured data is transmitted to controller 32 and analysed to provide a non-technical power theft indicator.

As previously discussed in detail, this analysis involves the use of Fourier analysis to determine the overall harmonic activity in each live phase in dependence upon the measured current through each live line and the generation of the total harmonic content in dependence upon the overall current in each live phase. Once the complete Fourier analysis has been completed this can be used to calculate the theoretical neutral current. Further analysis of the difference between the theoretical neutral current and the measured current through the neutral line at the selected point in the electrical network is used to provide an indication of non-technical power loss i.e. an indication of power theft (see step E of figure 16).

Once the assessment at step E is complete, the measured data and/or the outcome of the data analysis can be transmitted from the controller 32 to the display 22 (see step F of figures 16) for observation by a user (see step H of figure 16). This allows the user to obtain measured data and an indication of non-technical power loss at the selected point 16 in the electrical network 18 without the need for direct engagement with the meter test set 12. This further assists with the prevention of tampering at the selected point of interest 16 by a misguided user.

The smart device 14 as with any conventional smart device, has internet connectivity. Therefore, once the power loss indicator has been assessed (at step E), which can be done off-line, the measured data and results of the analysis and non-technical power loss indicator can be transmitted from the smart device 14 to a standard remote server or "cloud" server 34 (see step G of figure 16). Once the data is received by the remote or cloud server 34, the data may be used for onward further analysis and previously discussed in more detail (see step I of figure 16).

It is to be appreciated that the smart device may be constantly connected to the standard remote or cloud server and that data may be transmitted to them in real time. Alternatively, where internet connectivity is limited or it is desirable to minimise smart device battery power use, data can be stored by the smart device and uploaded to the remote server at a later time either via wireless internet connection, wireless local connection or wired connection. As the smart device 14 is portable, it is to be appreciated that the smart device 14 may transmit data to the remote server from the site where the meter test set 12 is located, or may be transported away from the site of the meter test set 12 and data transferred to the remote server 34 either from a distance via an internet communication or to the server 34 when in closer proximity via wired communication.

Claims (12)

1. CLAIMS: 1 A method for the detection of non-technical power loss at a selected point in an electrical network, the method comprising the steps of: a. on-site measurement of current through the live and neutral lines at the selected point in the electrical network; b. analysing the overall harmonic activity in each live phase in dependence upon the measured current through each live line; c. calculating the total harmonic content of the current in each live phase and the neutral in dependence upon the overall current in each live phase and the neutral; d. Calculating the theoretical neutral current in dependence upon the calculated total harmonic content in each phase and the neutral; e. Analysing the difference between the theoretical neutral current and the measured current through the neutral line at the selected point in the electrical network to provide a power theft indicator.
2. 2. A method as claimed in claim 1, wherein a difference between the theoretical neutral current and the measured neutral current is indicative of power theft.
3. 3. A method as claimed claim 2, wherein the difference between the theoretical neutral current and the measured neutral current is indicative of the level of power theft.
4. 4 A method as claimed in any preceding claim, wherein the on-site measurement of current measures the current through the live and neutral lines of a three phase, star (wye) connected system.
5. A method as claimed in any preceding claim, wherein Discrete Fourier Transform or Fast Fourier Transform is used for analysing the overall harmonic activity in each live phase.
6. 6 Apparatus for the detection of non-technical power loss at one or more selected points in an electrical network, the system comprising: a. One or more test sets, each test set comprising current measuring circuits operable for electrical engagement with the live and neutral lines at the selected point in the electrical network, wherein the test set is operable to transmit measured data from the test set; and b One or more portable smart devices, each portable smart device configured for wireless communication with a respective test set when located within wireless communication distance of the respective test set and operable to receive measured data from the test set and carry out the method of any one of claims 1 to 5.
7. 7. Apparatus as claimed in claim 6, wherein each test set further includes an antialiasing filter.
8. 8 Apparatus as claimed in claim 6 or claim 7, wherein each test set remains in situ over time at the selected point in the electrical network and each of the one or more portable smart device is moveable between test set locations within the electrical network.
9. 9 Apparatus as claimed in any one of claims 6 to 8, wherein each smart device further comprises a display for displaying one or more of the following for each test set it wirelessly communicates with: measured current through the live and neutral lines at a selected test point in the electrical network, the calculated Total Harmonic Distortion value for that test point, the total harmonic content per measure current for that test point, the power theft indicator for that test point, the level of power theft at the test point and identification data relating to the location of the test point within the electrical network.
10. 10. Apparatus as claimed in any one of claims 6 to 9, wherein the smart device is operable to transmit all measured and/or calculated data to a standard remote server or cloud server for further analysis.
11. 11 A system for the detection and quantification of non-technical power loss in an electrical network, the system comprising: a. One or more test sets, each test set comprising a current measuring circuit operable for electrical engagement with the live and neutral lines at a selected point in the electrical network, wherein each test set is operable to transmit measured data from the test set; b. One or more portable smart devices, each portable smart device configured for wireless communication with a respective test set when located within wireless communication distance of the respective test set and operable to receive measured data from the test set and carry out the method of any one of claims 1 to 5.c a remote or cloud server in wireless communication with the one or more portable smart devices and operable to receive data from each smart device for aggregation of data from multiple points in the electrical network and synchronisation of data to further evaluate power quality and theft in the electrical network.
12. 12. A system as claimed in claim 11, wherein each test set remains in situ over time at the selected point in the electrical network and each of the one or more portable smart device is moveable between test set locations within the electrical network.