METHOD FOR CALCULATING QUALIMETERICAL DATA, DEVICE, COUNTER AND SYSTEM

Description

TECHNICAL FIELD

[0001] At least one embodiment relates to a method for calculating quality data using a quality measurement device in communication with a meter on an electrical network. Other embodiments relate to a quality measurement device, a meter, and a system implementing said method. STATE OF PRIOR ART

[0002] Smart meters, such as electricity meters, thermal energy meters, or fluid meters (e.g., gas or water meters), are known to use communication interfaces that allow an automated management system to remotely collect meter data, such as consumption data. For example, these smart meters include one or more PLC (Power Line Communication) and / or radio communication interfaces. They then transmit meter data, for example, in the form of frames, via these communication interfaces, sending this consumption data, at regular or irregular intervals, to an information system for centralized processing. This consumption data is used by the information system, particularly for billing the customer by a service provider.

[0003] It is also known that, in its dealings with customers and suppliers, an electricity distributor monitors the quality of the electrical energy it supplies or receives. To monitor this quality, it is necessary to identify the disturbances that the electrical signal may undergo. Voltage surges and dips, flicker, network frequency variations, and harmonics are examples of parameters representative of such disturbances. The EN 61000-4-30 Class A standard defines measurement, time aggregation, accuracy, and evaluation methods to be applied to each parameter to obtain reliable, reproducible, and comparable quality data. Class A is particularly useful when precise data is required, for example, for contractual applications that may necessitate verification of conformity to standards, dispute resolution, and so on.

[0004] The PQI-D device from GMC Instruments is an example of a Class A certified power quality measurement device for calculating power quality data for the medium and high voltage sections of a distribution network. However, such a device, which is expensive, is not suitable for calculating power quality data in the lower part of the distribution network, i.e., closest to the end consumer. Another relevant example of the prior art is described in document FR 2 832 502 A1.

[0005] It is desirable to address these various drawbacks of the current state of the art. In particular, it is desirable to propose a method for collecting quality data that allows for obtaining quality data as close as possible to the end consumer with limited additional cost. DESCRIPTION OF THE INVENTION

[0006] Methods for calculating qualitative data, a qualitative device and a meter for an electrical network according to the invention are respectively defined in independent claims 1, 5, 7 and 8. Other embodiments of the invention are specified in the accompanying dependent claims.

[0007] A system comprising a quality measurement device communicating via a serial link with a counter is also described.

[0008] A computer program product is described that includes instructions for implementing the method of calculating qualitative data according to one of the preceding embodiments, when said program is executed by at least one processor. A storage medium is described that stores a computer program including instructions for implementing the method of calculating qualitative data according to one of the preceding embodiments when said program is executed by at least one processor. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The features of the invention mentioned above, as well as others, will become clearer upon reading the following description of an exemplary embodiment, said description being made in relation to the accompanying drawings, among which: [ Fig. 1] schematically illustrates a meter reading system in which the different embodiments described can be implemented; [ Fig. 2 ] schematically illustrates a method for calculating qualitative data according to a particular implementation; [ Fig. 3 ] schematically illustrates an example of the hardware architecture of a qualimetry device according to a particular embodiment; and, [ Fig. 4 ] schematically illustrates an example of the hardware architecture of a meter according to a particular embodiment. DETAILED DESCRIPTION OF IMPLEMENTATION METHODS

[0010] There Fig. 1This schematically illustrates a meter reading system 100 in which the different embodiments described below can be implemented. The meter reading system 100 is configured to collect meter data, including consumption data, from N smart meters C. On the Fig.1 Only one meter is shown. Smart meters C are electricity meters configured to measure electricity consumption using metrology software. These smart meters C can communicate with an Information System (IS) via a NET1 communication network using radio transmission and / or PLC or cellular (2G, 3G, 4G, or 5G). They can communicate with the Information System either directly or through data concentrators not shown in the diagram. Fig. 1 The role of the information system (IS) is, in particular, to monitor the measurement operations carried out by the smart meters C.

[0011] To monitor the quality of the supplied electricity, the electricity distributor uses a mobile power quality monitoring device (Q) that is powered either directly by the electricity distribution network or by battery. This device can be moved and connected to a specific meter (C) for a predefined analysis period, e.g., one week. This allows the quality of the electricity supplied at the distribution point to be verified during this time. For this purpose, the Q power quality monitoring device is connected to the meter (C) via a serial link, e.g., a twisted-pair cable of type RS-485 or RS-422 allowing a data rate of several Mbps. More precisely, a serial port on the Q power quality monitoring device is connected by the cable to a serial port on the meter (C). In one embodiment, the serial link between the Q power quality monitoring device and the meter (C) is unidirectional, i.e.Data is transmitted in frame form only from counter C to the quality monitoring device Q. In one embodiment, the serial link between the quality monitoring device Q and counter C is bidirectional. In this case, an acknowledgment frame is sent by the quality monitoring device Q to counter C each time the quality monitoring device Q receives a data frame from counter C.

[0012] In one embodiment, the data is transmitted asynchronously by the counter C to the quality measurement device Q. In another embodiment, the data is transmitted synchronously by the counter C to the quality measurement device Q. In this latter embodiment, the counter C then sends its clock signal to the quality measurement device Q so that the quality measurement device Q synchronizes its own clock with that of the counter C. Whether the serial link operates in synchronous or asynchronous mode, it does so based on the HDLC (High Definition Language 2) communication protocol. High-Level Data Link Control Alternatively, the serial link can use the frame relay protocol or Frame Relay in English.

[0013] The Q quality measurement device is also configured to communicate with the information system (IS) via a NET2 communication network, e.g., the Internet. Specifically, the IS retrieves the calculated quality measurement data from the Q quality measurement device. In other embodiments, the NET2 communication network is a wireless communication network, for example, GPRS (General Packet Radio Service), UMTS / 3G (Universal Mobile Telecommunication System), LTE (Long-Term Evolution), NB-IoT (Narrowband Internet of Things), 2G, 4G, or 5G, or LoRa (an acronym for " Long Range").

[0014] There Fig. 2 This schematically illustrates a method for calculating qualimetric data according to a particular embodiment. In this embodiment, the serial connection between the qualimetry device Q and the counter C is considered to be unidirectional and asynchronous.

[0015] During an S100 step, counter C sends a synchronization frame to the quality monitoring device Q at the beginning of each new period T, e.g., T = 1 s, of counter C's clock. This synchronization frame indicates to the quality monitoring device Q the start of a new period T. The quality monitoring device Q, upon receiving this synchronization frame, is then able to determine when the new period T actually began on the counter side. Indeed, it inherently knows the time lag Δt that exists between the actual start of the new period T on the counter side and the reception of the synchronization frame. Therefore, when it receives the synchronization frame at time t, it deduces that period T began at time t - Δt on the counter side.This last piece of information allows the Q qualimetry device to determine exactly on which second (view of its clock which it calibrates to that of the counter) the qualimetric data calculations are made from the samples of said second.

[0016] In one particular embodiment, the synchronization frame includes in its payload the information mentioned in the table below. Type in the Payload Number of bytes Frame type 1 Meter serial number 9 Characteristic data 1 Sampling frequency 1 Network frequency 2 UTC time 6

[0017] The frame type is specified using 1 byte and indicates, for example, that a value of 0 indicates a synchronization frame. Of course, this is simply a convention.

[0018] The serial number of counter C is specified using 9 bytes.

[0019] Characteristic data relating to the operation of the meter is indicated in 1 byte. This data includes, in particular, the following information: o A 1-bit piece of information representing the sampling type, e.g., ▪ 0 = number of sample frames fixed per network period ▪ 1 = number of sample frames fixed per period T, e.g., per second o A 2-bit piece of information representing the type of meter C, e.g., ▪ 00 = single-phase ▪ 01 = three-phase without neutral ▪ 10 = three-phase with neutral ▪ 11 = not used o A 1-bit piece of information indicating whether the neutral current is measured by the meter C, e.g., ▪ 0 = measured ▪ 1 = not measured o A 4-bit piece of information that is not used

[0020] This data allows the quality measurement device to interpret subsequently received sample frames.

[0021] Thus, if meter C is three-phase without a neutral, the power quality monitoring device Q knows that it will subsequently receive samples for each of the three phases but not for the neutral. The same applies if the synchronization frame indicates a three-phase meter C with a neutral, but the neutral current is indicated as "not measured." The sampling type indicates whether the number of sample frames subsequently sent is fixed per network period (the network period being equal to the inverse of the network frequency) or per period T, e.g., per second. This information allows the power quality monitoring device Q to know whether to expect a fixed number N of sample frames per second or not.

[0022] The sampling frequency of counter C is indicated in 1 byte. This data is necessary for the quality measurement device to perform Fourier transforms in order to calculate voltage and current harmonics in the next step.

[0023] The network frequency, e.g., 50 or 60 Hz, measured over a previous period T and applied to the current period T, is indicated using two bytes. This data is necessary for the quality measurement device to calculate the quality measurement data, which are calibrated to the network period as indicated in sections 4.4 and 4.5.2 of document EN 61000-4-30.

[0024] Optionally, the frame includes the Coordinated Universal Time (UTC) time from counter C, represented by 6 bytes. This UTC time is used by the quality measurement device to timestamp the quality measurement data it calculates. Alternatively, the quality measurement device Q retrieves the UTC time from the SI system if it does not need to be transmitted by the counter in the synchronization frame.

[0025] During step S102, counter C sends N samples sequentially over period T, each sample transmitted in a frame. These samples are derived from the analog-to-digital conversion of voltage and current signals for each phase (in the case of a multi-phase signal) and, if applicable, the neutral. They are also calibrated for gain. Thus, each frame contains data sampled at a specific sampling time determined by counter C, and which has undergone a gain calibration correction.

[0026] In a particular embodiment, the sample frame includes in its payload the information listed in the table below for the specific case of a three-phase electrical signal with a neutral. Naturally, in the case of a single-phase signal with a neutral, the data relating to phases 2 and 3 are absent, and in the case without a neutral measurement, the data relating to the neutral is absent. Type in payload Number of bytes Frame type 1 Frame number 2 Phase 1 Voltage 2 Phase 1 Current 3 Phase 2 Voltage 2 Phase 2 Current 3 Phase 3 Voltage 2 Phase 3 Current 3 Neutral Current 3

[0027] The frame type is specified using one byte and indicates, for example, that a value of 1 indicates a sample frame. This is, of course, simply a convention. The frame includes a frame number, which is zero for the first sample frame sent after the start of the first period T. This value is then incremented by 1 with each subsequent transmission by the frame counter. Thus, the quality monitoring device Q, which receives the sample frames, can verify the consistency of the received frames and, in case of inconsistency, display an error message on its screen.

[0028] Each voltage sample calibrated in gain is represented on 2 bytes.

[0029] Each gain-calibrated current sample is represented on 3 bytes.

[0030] The synchronization and sample data are then encapsulated in an HDLC frame before transmission to the Q qualimetric device.

[0031] Steps S100 and S102 are repeated over a subsequent period T until the end of the predefined analysis period, e.g., one week. Thus, during each period T, the quality measurement device Q collects samples sent by the meter C. During step S104, it continuously calculates, for each phase and, where applicable, for the neutral, according to standard EN 61000-4-30, quality data from the received samples.Examples of quality data types calculated during step S104 include: power frequency, supply voltage amplitude, short- and long-duration flicker, power voltage dips and temporary power frequency surges, supply voltage interruptions, transient voltages, supply voltage imbalance, voltage harmonics, voltage interharmonics, signal transmission voltage over the supply voltage, rapid voltage change (RVC), high and low voltage values, current amplitude, current recording, current harmonics, current interharmonics, and current imbalance. At least one type of quality data is calculated during step S104.In another embodiment, several types of quality data are calculated from among those listed above, e.g., voltage harmonics, current harmonics, and short-duration flicker. Step S104 is performed in parallel with steps S100 and S102. The calculation of quality data during step S104 is performed synchronously with the grid period as described in sections 4.4 and 4.5.2 of EN 61000-4-30 for Class A.

[0032] Thus, the quality measurement device Q calculates quality data over a time period T', e.g., T' = 10 minutes, and timestamps it with a time determined according to UTC. The calculated and timestamped quality data is stored in memory by the quality measurement device Q. An example of calculated quality data for Class A over the time period T' is shown in Table 1 below for a three-phase electrical signal: Table 1 - Case of an electricity meter Phase 1 voltage harmonics U1 Fundamental U1 Harmonic 2 ... U1 Harmonic 50 Phase 2 voltage harmonics U2 Fundamental U2 Harmonic 2 ... U2 Harmonic 50 Phase 3 voltage harmonics U3 Fundamental U3 Harmonic 2 ... U3 Harmonic 50 Phase 1 current harmonics I1 Fundamental I1 Harmonic 2 ... I1 Harmonic 50 Phase 2 current harmonics I2 Fundamental I2 Harmonic 2 ... I2 Harmonic 50 Phase 3 current harmonics I3 Fundamental I3 Harmonic 2 ... I3 Harmonic 50 Short-duration flickering for each of the 3 phases Pst fluttering (phase 1) Pst fluttering (phase 2) Pst fluttering (phase 3) Time and date UTC time of data

[0033] In this example, over a time interval T', e.g., T' = 10 minutes, the power quality measurement device Q calculates, for each phase, 50 voltage harmonics and 50 current harmonics from voltage and current samples received from the meter C. Of course, the method is not limited to the case of 50 harmonics. Thus, more than 50 or fewer than 50 harmonics can be calculated. For each phase, a short-duration flicker, denoted Pst, is also calculated. These data are timestamped with the UTC time corresponding to the beginning or end of the calculation interval. The embodiment described for a three-phase electrical signal applies similarly to a single-phase electrical signal. In this case, the data (voltage and current harmonics as well as the short-duration flicker) are calculated for a single phase.

[0034] The calculations of the data mentioned in the table above are carried out in the manner described in the EN 61000-4-30 standard for Class A.

[0035] Thus, in a specific implementation, the Q quality measurement device performs an FFT (Fast Fourier Transform) on the received samples, taking into account the sampling frequency indicated in the synchronization frame, over a given time period Δtps, e.g., Δtps = 200 ms, which corresponds to 10 periods of 20 ms at 50 Hz (12 periods of 16.67 ms at 60 Hz), in order to calculate the 50 harmonics of voltage and current, and the short-duration flicker over this period Δtps. Then, the Q quality measurement device aggregates, for each parameter in the table, over an interval of 150 periods (180 periods at 60 Hz), the results previously calculated over 15 periods Δtps (also 15 periods Δtps at 60 Hz). Aggregations are calculated by taking quadratic means, i.e. by calculating the square root of the arithmetic mean of the square of the input values.The Q quality measurement device performs a root mean square (RMS) calculation over 10 minutes for each parameter in the table. The results of these calculations are known in the literature as "aggregated 10-minute values." The Q quality measurement device timestamps these calculated quality data with, for example, the start or end time of the 10-minute interval. The example described for a 10-minute interval applies similarly to other time interval values ​​T'.

[0036] There Fig. 3 schematically illustrates an example of the hardware architecture of a 140 quality measurement device according to a particular embodiment. According to the hardware architecture example shown in the Fig. 3The quality measurement device 140 then comprises, connected by a communication bus 1400: a processor or CPU (“Central Processing Unit”) 1401; a RAM (“Random Access Memory”) 1402; a ROM (“Read Only Memory”) 1403; a storage unit 1404 such as a hard disk drive or such as a storage media reader, e.g. an SD card reader (“Secure Digital”); at least one first communication interface 1405 allowing the quality measurement device 140 to send information to the management entity SI and, where applicable, to receive information, and a second communication interface 1406 allowing the quality measurement device 140 to send or receive information from the counters.

[0037] For example, the first 1405 communication interface is compliant with the LoRa, NB-IoT, GPRS, UMTS / 3G, LTE, 2G, 4G or 5G standard. The second interface is a serial port (typically RS-485 or RS-422).

[0038] The processor 1401 is capable of executing instructions loaded into RAM 1402 from ROM 1403, external memory (not shown), storage media (such as an SD card), or a communication network. When the quality control device 140 is powered on, the processor 1401 can read instructions from RAM 1402 and execute them. These instructions form a computer program that causes the processor 1401 to implement all or part of the process described in relation to the Fig. 2 .

[0039] The process described in relation to the Fig. 2can be implemented in software form by executing a set of instructions by a programmable machine, for example a DSP (Digital Signal Processor) or a microcontroller, or it can be implemented in hardware form by a dedicated machine or component, for example an FPGA (Field-Programmable Gate Array) or an ASIC (Application-Specific Integrated Circuit). In general, the quality measurement device 140 includes electronic circuitry configured to implement the described process in relation to the Fig. 2 .

[0040] There Fig. 4 schematically illustrates an example of the hardware architecture of a 150 meter according to a particular embodiment. According to the hardware architecture example shown in the Fig. 4The counter 150 then comprises, connected by a communication bus 1500: a processor or CPU (Central Processing Unit) 1501; a RAM (Random Access Memory) 1502; a ROM (Read Only Memory) 1503; a storage unit 1504 such as a hard drive or a storage media reader, e.g., an SD card reader (Secure Digital); at least one communication interface 1505 allowing the counter 150 to send or receive information from the quality measurement device 140. The communication interface 1505 is a serial port (typically RS-485 or RS-422). The counter 150 generally includes another communication interface not shown in the diagram. Fig. 4allowing it to communicate with the IS either directly (in cellular 2G, 3G, 4G or 5G) or through a data concentrator (typically in PLC or hybrid mode, i.e. by PLC and radio), for example for collecting consumption data.

[0041] The 1501 processor is capable of executing instructions loaded into RAM 1502 from ROM 1503, external memory (not shown), storage media (such as an SD card), or a communication network. When counter 150 is powered on, the 1501 processor can read instructions from RAM 1502 and execute them. These instructions form a computer program that causes the 1501 processor to implement all or part of the process described in relation to the Fig. 2 .

[0042] The process described in relation to the Fig. 2can be implemented in software form by executing a set of instructions by a programmable machine, for example a DSP (Digital Signal Processor) or a microcontroller, or it can be implemented in hardware form by a dedicated machine or component, for example an FPGA (Field-Programmable Gate Array) or an ASIC (Application-Specific Integrated Circuit). Generally speaking, the 150 counter includes electronic circuitry configured to implement the described process in relation to the Fig. 2 .

Claims

1. A method for calculating qualimetric data by a qualimetry device (Q) in communication with a meter (C) of an electricity network through a serial connection, said method comprising the following steps performed by the qualimetry device (Q): - receiving (S100) at a time t a synchronisation frame coming from said meter (C), said synchronisation frame comprising an identifier indicating that said frame is a synchronisation frame, a serial number of the meter (C), information representing the type of meter (C), information indicating whether the neutral current is being measured by said meter (C), a sampling and frequency type, and a frequency of said electricity network, and applying a time difference Δt at the time t to determine the start of a period (T) of a clock of the meter (C) by calculating t-Δt to reset a clock of the qualimetry device (Q) to the clock of the meter (C), the time difference Δt corresponding to the difference between an actual start of the period (T) of the clock of the meter and the reception of the synchronisation frame by the qualimetry device (Q); - receiving (S102), during the period (T), N frames of samples coming from said meter (C), N being a positive integer, each frame of samples comprising an identifier indicating that said frame is a frame of samples, and a number of a frame of samples and of voltage and current samples for at least one phase; and - calculating (S104) qualimetric data from the information included in said synchronisation frame and in at least some of said N frames of samples.

2. The calculation method according to claim 1, wherein said synchronisation frame furthermore comprises information representing a UTC time.

3. The calculation method according to claim 1 or 2, wherein said frames are frames conforming to the HDLC protocol.

4. The calculation method according to one of claims 1 to 3, wherein said calculated qualimetric data belong to all the types of qualimetric data comprising: an industrial frequency, a supply voltage amplitude, a short-duration flicker, a long-duration flicker, a trough of the supply voltage and of temporary industrial-frequency overvoltages, breaks in the supply voltage, transient voltages, an imbalance in the supply voltage, voltage harmonics, voltage interharmonics, a signal transmission voltage on the supply voltage, rapid voltage variations, a low voltage value and a high voltage value, an amplitude of the current, a recording of the current, current harmonics, current interharmonics, and a current imbalance.

5. A method for calculating qualimetric data by a qualimetry device according to claim 7, in communication with a meter (C) of an electricity network through a serial connection, said method comprising the following steps performed by the meter (C): - sending (S100) a synchronisation frame at a time t to said qualimetry device (Q), said synchronisation frame comprising an identifier indicating that said frame is a synchronisation frame, a serial number of the meter (C), information representing the type of meter (C), information indicating whether the neutral current is being measured by said meter (C), a sampling and frequency type, and a frequency of said electricity network, and - sending (S102), during a period (T), N frames of samples to said qualimetry device (Q), N being a positive integer, each frame of samples comprising an identifier indicating that said frame is a frame of samples, and a number of a frame of samples and of voltage and current samples for at least one phase.

6. The calculation method according to claim 5, wherein said synchronisation frame furthermore comprises information representing a UTC time.

7. A qualimetric device configured to be in communication with a meter (C) of an electricity network through a serial connection, said qualimetric device comprising electronic circuitry configured to: - receive (S100) at a time t a synchronisation frame coming from said meter (C), said synchronisation frame comprising an identifier indicating that said frame is a synchronisation frame, a serial number of the meter (C), information representing the type of meter (C), information indicating whether the neutral current is being measured by said meter (C), a sampling and frequency type, and a frequency of said electricity network, and apply a time difference Δt at the time t to determine the start of a period (T) of a clock of the meter (C) by calculating t-Δt to reset a clock of the qualimetry device (Q) to the clock of the meter (C), the time difference Δt corresponding to the difference between an actual start of the period (T) of the clock of the meter and the reception of the synchronisation frame by the qualimetry device (Q); - receive (S102), during the period (T), N frames of samples coming from said meter (C), N being a positive integer, each frame of samples comprising an identifier indicating that said frame is a frame of samples, and a number of a frame of samples and of voltage and current samples for at least one phase; and - calculate (S104) qualimetric data from the information included in said synchronisation frame and in at least some of said N frames of samples.

8. A meter (C) of an electricity network configured to be in communication through a serial connection with a qualimetric device according to claim 7 configured to calculate qualimetric data, said meter (C) comprising electronic circuitry configured to: - send (S100) a synchronisation frame at a time t to said qualimetry device (Q), said synchronisation frame comprising an identifier indicating that said frame is a synchronisation frame, a serial number of the meter (C), information representing the type of meter (C), information indicating whether the neutral current is being measured by said meter (C), a sampling and frequency type, and a frequency of said electricity network, and - send (S102), during a period (T), N frames of samples to said qualimetry device (Q), N being a positive integer, each frame of samples comprising an identifier indicating that said frame is a frame of samples, and a number of a frame of samples and of voltage and current samples for at least one phase.

9. A system (100) comprising a qualimetric device (Q) according to claim 7 in communication through a serial connection with a meter (C) according to claim 8.

10. A computer program product comprising instructions for implementing the method for calculating qualimetric data according to any one of claims 1 to 6, when said program is executed by at least one processor.

11. A storage medium storing a computer program comprising instructions for implementing the method for calculating qualimetric data according to any one of claims 1 to 6 when said program is executed by at least one processor.