METHOD FOR ESTABLISHING THE ELECTRICAL CONSUMPTION OF AN ELECTRICAL INSTALLATION

Abstract

To establish the electrical consumption of an electrical installation that is supplied by at least one phase and monitored by an electricity meter, a method implemented by an electricity meter controller involves: obtaining (601, 603), for each phase, voltage measurement samples and current measurement samples; applying (602) an amplitude adjustment KU and a phase adjustment Δφ to the voltage measurement samples to obtain adjusted voltage samples; applying (604) an amplitude adjustment KI and a phase adjustment Δφ' to the current measurement samples to obtain adjusted current samples; performing (605) at least one power calculation from the adjusted current samples; and establishing (606) the electrical consumption from said at least one power calculation. Figure to be published with the abbreviation: Fig. 6

Description

Title of the invention: METHOD FOR ESTABLISHING THE ELECTRICAL CONSUMPTION OF AN ELECTRICAL INSTALLATION Technical field

[0001] The present invention relates to an adjustment of measurements by an electric meter in order to take into account inaccuracies in the characteristics of components of the electric meter which are used to carry out voltage and current measurements serving to establish an electric consumption of an electrical installation supervised by the electric meter. STATE OF PRIOR ART

[0002] In order to establish the electrical consumption of an electrical installation, an electrical meter performs power calculations using samples of alternating voltage and current measurements at the input of the electrical installation. The alternating voltage and current measurements are carried out using electronic components: voltage measurements are typically carried out using voltage divider bridges; in single-phase, current measurements are typically carried out using measurement shunts; in polyphase (eg, three-phase), current measurements are typically carried out using toroids.

[0003] [Fig.l] schematically illustrates an arrangement for obtaining measurement samples of alternating voltage and current, between a phase line P and a neutral line N, in a single-phase electric meter.

[0004] A voltage divider bridge is made using resistors RI and R2 between the neutral line N and the ground. An analog-digital converter C2 placed at a junction point of resistors RI and R2 makes it possible to obtain voltage measurement samples.

[0005] A shunt, made by a calibrated resistor R3, is placed on the phase line P. The phase line P is here connected to ground. A current measurement chain CMC coupled to an analog-digital converter Cl makes it possible to obtain current measurement samples.

[0006] The electric meter comprises a CTRL controller configured to establish an electric consumption from power calculations carried out from the obtained alternating voltage and current measurement samples, as described below in relation to [Fig.3].

[0007] [Fig.2] schematically illustrates an arrangement for obtaining measurement samples of alternating voltage and current, between a phase line P and a line of neutral N, in a polyphase electric meter (eg, three-phase). The neutral line N is here connected to ground.

[0008] A voltage divider bridge is made using resistors RI and R2 between the phase line P in question and ground. An analog-digital converter C2 placed at a junction point of resistors RI and R2 makes it possible to obtain voltage measurement samples.

[0009] A toroid T is placed on the phase line P, with a resistor R4 in parallel. A current measurement chain CMC coupled to an analog-digital converter Cl makes it possible to obtain current measurement samples.

[0010] The arrangement of [Fig.2] is replicated for each phase, the CTRL controller being however common to the different phases. The CTRL controller is thus configured to establish an electrical consumption from power calculations carried out from the AC voltage and current measurement samples obtained for each of the phases.

[0011] The actual characteristics of shunts, cores and resistors are specific to each electric meter. For example, the accuracy of a shunt is given as ±5%, that of resistors as ±1% and a core can phase shift the current signal by several degrees. It is then usual to adjust the results of power calculations to compensate for a difference in the actual accuracy of the characteristics of the electronic components used to carry out the AC voltage and current measurements.

[0012] Thus, as illustrated in [Fig.3], the controller CTRL performs for example an active power calculation P and a reactive power calculation Q, from the obtained voltage U and current I measurement samples. The phase shift and the gain due to the toroid for each phase in polyphase (eg, three-phase), or to the shunt in single-phase, are compensated by adjusting the powers P and Q using a matrix calculation MAT in order to obtain a corrected active power Pm and a corrected reactive power Qm. The matrix calculation MAT includes respectively a predefined phase compensation Aq) and a predefined amplitude compensation K.

[0013] Given that power calculations are complex calculations integrating a multiple sum of multiplications of voltage and current samples, compensation in phase Aq) ” and in amplitude K at the level of these power calculations results in a residual inaccuracy. This residual inaccuracy is all the more significant in polyphase (eg, three-phase) because the phase shifts, in particular linked to the toroids, are different from one phase to another.

[0014] It is then desirable to overcome these drawbacks of the state of the art. Statement of the invention

[0015] A method is proposed here for establishing an electrical consumption of an ins electrical installation which is electrically powered by at least one phase and which is supervised by an electric meter, the method being implemented by a controller of the electric meter and comprising: obtaining, for each phase, voltage measurement samples and current measurement samples; applying an amplitude adjustment Ku and a phase adjustment Aq) on the voltage measurement samples to obtain adjusted voltage samples; applying an amplitude adjustment K[ and a phase adjustment Aq>' on the current measurement samples to obtain adjusted current samples; performing at least one power calculation from the adjusted current samples; and establishing the electrical consumption from said at least one power calculation.

[0016] Thus, by applying the amplitude and phase adjustment to the measurement samples rather than to said at least one power calculation, better metrology accuracy is obtained.

[0017] According to a particular embodiment, the method further comprises: applying a complementary adjustment K) to the current measurement samples to compensate for a spread of voltage measurement samples on the current measurement samples.

[0018] According to a particular embodiment, the phase adjustment Aq> is applied by interpolation, where between two successive voltage measurement samples U„ i and Un at respective times tn = (n-1) x TE and tn = nx TE following a sampling period TE, the interpolation provides a sample Un !+r at a fictitious sampling time ln i+r = (n-1+r) x TE, with r such that Aq>=2m\ and the phase adjustment Aq> ' is applied by interpolation, where between two successive current measurement samples In, and In at the respective times tn^ = (n-1 ) x TE and tn = nx TE, the interpolation provides a sample In_i+E at a fictitious sampling time tn_1+E = (n-l+r') x Te, with r' such that Aq>'=2nr'.

[0019] According to a particular embodiment, the interpolation is linear.

[0020] According to a particular embodiment, the electrical installation which is supervised by the electricity meter is supplied in three-phase. Thus, the amplitude and phase adjustment on the measurement samples is even more precise than would be an amplitude and phase adjustment on said at least one power calculation (particularly due to distinct phase shifts introduced by toroids used on the phases to carry out the current measurement).

[0021] According to a particular embodiment, said at least one power calculation is a calculation of active power and / or reactive power and / or apparent power.

[0022] Also provided herein is a computer program comprising program code instructions causing an implementation of the method, when said instructions are executed by a smart meter processor.

[0023] Also provided herein is an information storage medium storing such program code instructions.

[0024] Also proposed here is an electric meter controller, which is configured to establish an electric consumption of an electrical installation which is electrically supplied by at least one phase and which is supervised by the electric meter, said controller comprising electronic circuitry configured to: obtain, for each phase, voltage measurement samples and current measurement samples; apply an amplitude adjustment Ku and a phase adjustment Aq) on the voltage measurement samples to obtain adjusted voltage samples; apply an amplitude adjustment and a phase adjustment Aq) ' on the current measurement samples to obtain adjusted current samples; perform at least one power calculation from the adjusted current samples; and establish the electric consumption from said at least one power calculation.

[0025] Also proposed here is an electric meter equipped with the above controller. Brief description of the drawings

[0026] The characteristics of the invention mentioned above, as well as others, will appear more clearly on reading the following description of at least one exemplary embodiment, said description being made in relation to the attached drawings, among which:

[0027] [Fig. 1] schematically illustrates an arrangement for obtaining voltage and current measurement samples in a single-phase electric meter;

[0028] [Fig.2] schematically illustrates an arrangement for obtaining voltage and current measurement samples per phase in a polyphase electricity meter;

[0029] [Fig.3] schematically illustrates an arrangement for performing a power calculation to establish electrical consumption, according to the state of the art;

[0030] [Fig.4] schematically illustrates an arrangement for performing a power calculation to establish an electrical consumption, according to an embodiment of the present invention;

[0031] [Fig.5] schematically illustrates an example of a hardware arrangement of an electric meter controller;

[0032] [Fig.6] schematically illustrates an algorithm for performing a power calculation to establish an electrical consumption, according to an embodiment of the present invention; and

[0033] [Fig.7] schematically illustrates an example of linear interpolation used to phase adjust samples, according to an embodiment of the present invention.

[0034] DETAILED DESCRIPTION OF EMBODIMENTS

[0035] [Fig.4] schematically illustrates an arrangement for performing a power calculation to establish an electrical consumption, according to an embodiment of the present invention. The power calculation is performed to establish an electrical consumption of an electrical installation which is electrically supplied by at least one phase and which is supervised by an electric meter. [Fig.4] relies on the arrangement of [Fig.1] or that of [Fig.2] to obtain samples of voltage and current measurements.

[0036] [Fig.4] includes an active power calculation P and a reactive power calculation Q. But instead of basing these power calculations on the raw voltage U and current I measurement samples as in [Fig.3], the active power P and reactive power Q calculations use voltage and current samples adjusted in amplitude and phase. Thus, the voltage U measurement samples provided by the analog-digital converter C2 undergo an adjustment A2 in amplitude (gain Kv) and in phase Aq), and the current I measurement samples provided by the analog-digital converter C1 undergo an adjustment Al in amplitude (gain Ki) and in phase Aq)' (adjustment typically different than for the voltage U measurement samples).

[0037] By obtaining the corrected active power Pm and the corrected reactive power Qm by performing the active power P and reactive power Q calculations from amplitude and phase adjusted voltage and current samples, rather than performing amplitude and phase compensation after the active power P and reactive power Q calculations, the accuracy of power consumption measurement is improved.

[0038] [Fig.5] schematically illustrates an example of a hardware arrangement of the CTRL controller which is suitable for power and electrical consumption calculations according to the present invention.

[0039] The CTRL controller 500 comprises, connected by a communication bus 510: a processor or CPU (Central Processing Unit) 501; a random access memory (RAM) 502; a read-only memory 503, for example of the ROM (Read Only Memory) or EEPROM (Electrically Erasable Programmable ROM) type, such as a Flash memory; a storage medium SM 504, such as a hard disk drive (HDD) or an SD card reader (Secure Digital); and an I / f interface manager 505.

[0040] The I / f interface manager 505 allows the CTRL controller 505 to interact with other equipment of the electric meter, such as for example a transceiver when the electric meter is a communicating meter. The ges The I / f interface manager 505 allows the CTRL 500 controller to receive the U and I voltage measurement samples from the analog-to-digital converters. In an alternative embodiment, the analog-to-digital converters are included in the CTRL 500 controller, for example in the I / f interface manager 505.

[0041] The processor 501 is capable of executing instructions loaded into the RAM 502 from the ROM 503, an external memory, a storage medium (such as an SD card), or a communications network. When the CTRL controller 500 is powered on, the processor 501 is capable of reading instructions from the RAM 502 and executing them. These instructions form a computer program causing the processor 501 to implement all or part of the steps, methods, and operations described herein.

[0042] All or part of the steps, methods and operations described herein may thus be implemented in software form by executing a set of instructions by a programmable machine, for example a DSP (Digital Signal Processor) type processor or a microcontroller, or be implemented in hardware form by a machine or a dedicated electronic component (chip) or a set of dedicated electronic components (chipset), for example an FPGA (Field Programmable Gate Array) or ASIC (Application Specified Integrated Circuit) component. Generally speaking, the CTRL 500 controller (and therefore the electricity meter) comprises electronic circuitry adapted and configured to implement the operations, methods and steps described herein.

[0043] [Fig.6] schematically illustrates an algorithm for performing a power calculation to establish electrical consumption, according to an embodiment of the present invention.

[0044] In a step 601, the controller CTRL obtains voltage measurement samples.

[0045] In a step 602, the controller CTRL performs an adjustment in phase Aq) and in amplitude Ku of the voltage measurement samples obtained in order to obtain adjusted voltage samples.

[0046] Steps 601 and 602 are performed for each phase (i.e., for each of the three phases in three-phase).

[0047] In a step 603, the controller CTRL obtains current measurement samples.

[0048] In a step 604, the controller CTRL performs an adjustment in phase Aq) ' and in amplitude Ki of the current measurement samples obtained in order to obtain adjusted current samples.

[0049] Steps 603 and 604 are performed for each phase (i.e., for each of the three phases in three-phase).

[0050] In a particular embodiment, the controller CTRL obtains a phase-adjusted voltage sample Un!+r by interpolation between the obtained voltage measurement sample Un^ and the obtained voltage measurement sample Un, by defining r such that A(p=2m\ then by applying the amplitude adjustment Kv. And similarly, the controller CTRL obtains a phase-adjusted current sample In.I+E by interpolation between the obtained current measurement sample In., and the obtained current measurement sample ln, then by applying the amplitude adjustment K, (by defining r' such that Acp'=2m-').

[0051] Interpolation can be quadratic, cubic or spline.

[0052] In a particular embodiment, the interpolation is linear, as schematically illustrated in [Fig.7]. [Fig.7] comprises points, on a sinusoidal curve, which represent measurement samples (of voltage or current) as provided by a said analog-to-digital converter. The time is represented on the abscissa and the values ​​of the measurement samples are represented on the ordinate.

[0053] The samples correspond to measurements made (provided by the analog-digital converters) according to a sampling period TE, for example equal to 384.62 ps, therefore corresponding to a sampling frequency fE of 2600 Hz. The points A„, and An correspond to successive measurement samples, at respective measurement times tn^ = (n-1 ) x TE and tn = nx TE., and have respective measurement values ​​V,,, and Vn. The point An i+r is an interpolated point at a fictitious measurement time tn.I+r = (n-l+r) x Te, with an interpolated amplitude value Vn,]+r. Then: Vn.]+r =rx Vn + (1-r) x Vnj. Linear interpolation is advantageously simple in calculations and requires few resources.

[0054] Thus, for each phase:

[0055] lU^+Wrx Un + (lr)x U^)

[0056] Li+e = (1+ KJ x (r' xl„ + (1-r') x ln_J

[0057] KUt Kb r and r' are constants specific to each electric meter and each phase. KUt Kb r and r' are factory calibrated using measurements for which the expected result is known and towards which one must aim. This consists of solving a system of multiple equations with several unknowns.

[0058] In a particular embodiment, the CTRL controller performs a complementary adjustment of the current measurement samples to compensate for a spread of the voltage samples over the current samples. Such a spread has been observed on certain analog-to-digital converters which provide the voltage and current samples in the form of multiplexed channels. The controller CTRL then applies a gain K', on the corresponding (adjusted) voltage sample Un-]+r for the phase concerned. Then, in the case of the linear interpolation explained above, the current samples are adjusted, for each phase, as follows:

[0059] InUr = (1+ K,) x (r' xl„ + (1-r') x In^) + K\ x Un !+r

[0060] In this case, Ku, Kh K'h r and r' are factory calibrated using measurements from which we knows the expected result and the one towards which we must aim. This consists of solving another system of multiple equations with several unknowns.

[0061] In a step 605, the controller CTRL performs at least one power calculation from the adjusted voltage and current samples (Un.I+r and In.I+r) for each phase.

[0062] The power calculation may be a calculation of active power and / or reactive power and / or apparent power.

[0063] In step 606, the controller CTRL establishes an electrical consumption of the electrical installation, based on said at least one power calculation of step 605.

[0064] It should be noted that, considering a three-phase electric meter which comprises 3 cores T1, T2 and T3, where core T1 is phase-shifted by Acpi (for example, +1.5°), core T2 is phase-shifted by A(p2 (for example, -0.7°) and core T3 is phase-shifted by A(p3 (for example, -1°), it is impossible to choose a sampling instant which allows these 3 phase shifts to be compensated simultaneously (since these phase shifts are of different values). It is therefore clear that it is preferable to interpolate the samples U and I as proposed in the solution rather than correcting phase shifts by varying the sampling instant.

Claims

Claims

1. Method for establishing an electrical consumption of an electrical installation which is electrically supplied by at least one phase and which is supervised by an electric meter, the method being implemented by a controller (500) of the electric meter and comprising: - obtaining (601, 603), for each phase, voltage measurement samples and current measurement samples; - applying (602) an amplitude adjustment Kv and a phase adjustment Aq) on the voltage measurement samples to obtain adjusted voltage samples; - applying (604) an amplitude adjustment and a phase adjustment Aq) ' on the current measurement samples to obtain adjusted current samples; - performing (605) at least one power calculation from the adjusted current samples; and - establishing (606) the electrical consumption from said at least one power calculation.

2. The method of claim 1, further comprising: -applying a complementary adjustment K'! to the current measurement samples to compensate for a spread of voltage measurement samples over the current measurement samples.

3. Method according to one of claims 1 and 2, in which the phase adjustment Aq) is applied by interpolation, where between two successive voltage measurement samples U„ i and Un at respective times = (n-1) x TE and tn = nx TE following a sampling period TE, the interpolation provides a sample U„ t+r at a fictitious sampling time tn.]+r = (n-1+r) x TE, with r such that Aq>=2m\ and the phase adjustment Aq>' is applied by interpolation, where between two successive current measurement samples Inl and In at the respective times tn^ = (n-1) x TEettn = nx TE, the interpolation provides a sample In.I+E at a fictitious sampling time ln i+r- = (n-1+r') x Te, with r' such that Aq>'=2nr'.

4.

5. Method according to claim 3, wherein the interpolation is linear. Method according to any one of claims 1 to 4, wherein the electrical installation which is supervised by the electric meter is supplied in three-phase.

6. A method according to any one of claims 1 to 5, wherein said at least one power calculation is a calculation of active power and / or reactive power and / or apparent power.

7. A computer program product comprising program code instructions causing an implementation of the method according to any one of claims 1 to 6, when said instructions are executed by an electric meter controller processor (500).

8. An information storage medium storing program code instructions causing an implementation of the method according to any one of claims 1 to 6, when said instructions are read and executed by an electric meter controller processor (500).

9. Electricity meter controller (500), which is configured to establish an electrical consumption of an electrical installation which is electrically supplied by at least one phase and which is supervised by the electric meter, said controller (500) comprising electronic circuitry configured to: - obtain (601, 603), for each phase, voltage measurement samples and current measurement samples; - apply (602) an amplitude adjustment Kv and a phase adjustment Aq) on the voltage measurement samples to obtain adjusted voltage samples; - apply (604) an amplitude adjustment and a phase adjustment Aq) ' on the current measurement samples to obtain adjusted current samples; - perform (605) at least one power calculation from the adjusted current samples; and - establish (606) the electrical consumption from said at least one power calculation.

10. An electric meter comprising a controller (500) according to claim 9.

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