DETECTING ABNORMAL METROLOGICAL DRIFT IN A FLUID METER

Abstract

A method of monitoring a fluid meter is arranged to produce measurements of the overall consumption of an installation. The method includes the steps of: analyzing the overall consumption measurements to identify a mechanism in the installation that operates with operating cycles, each presenting a substantially constant cycle duration (t1−t0) and during each of which the individual consumption (V1−V0) of the mechanism is substantially constant; detecting operating cycles of the mechanism and measuring the individual consumption of the mechanism for each detected operating cycle; detecting abnormal metrological drift of the measuring device as a function of variation over time in the individual consumption.

Claims

1. A monitoring method for monitoring a measuring device of a fluid meter that is arranged to produce measurements of the overall consumption of an installation, the method comprising the steps of: analyzing the overall consumption measurements to identify a mechanism in the installation that operates with operating cycles, each presenting a substantially constant cycle duration (t.sub.1−t.sub.0) and during each of which the individual consumption (V.sub.1−V.sub.0) of the mechanism is substantially constant; detecting the operating cycles of the mechanism and measuring the individual consumption of the mechanism for each detected operating cycle; detecting abnormal metrological drift of the measuring device of the fluid meter as a function of variation over time in the individual consumption of the mechanism.

2. The monitoring method according to claim 1, wherein identifying the mechanism comprises the steps of: detecting, in the overall consumption measurements, a reference operating cycle having a cycle duration and an individual consumption that are substantially equal to a previously-input cycle duration and to a previously-input individual consumption corresponding to a known mechanism; associating the mechanism with a reference cycle duration (t) equal to the cycle duration of said reference operating cycle and with a reference individual consumption (V) equal to the individual consumption of said reference operating cycle.

3. The monitoring method according to claim 1, wherein detecting an operating cycle comprises the steps of detecting, in the overall consumption of the installation, a succession of a first stable stage, of an increasing stage, and of a second stable stage.

4. The monitoring method according to claim 1, further comprising a step of detecting a change of mechanism from a variation in the cycle duration and/or from a variation in the individual consumption of the mechanism.

5. The monitoring method according to claim 4, wherein an identical replacement of the mechanism is detected when, starting from a first change time, the cycle duration no longer lies in a first interval centered on the reference cycle duration and the individual consumption no longer lies in a second interval centered on the reference individual consumption.

6. The monitoring method according to claim 5, wherein replacement of the mechanism by a non-identical mechanism is detected when, from a second change time, the cycle duration no longer lies in a third interval centered on the reference cycle duration and the individual consumption no longer lies in a fourth interval centered on the reference individual consumption, the third interval and the fourth interval being wider than the first interval and the second interval.

7. The monitoring method according to claim 1, wherein detecting abnormal metrological drift comprises the steps of: evaluating a drift function (P.sub.n) representative of drift of the individual consumption of the mechanism; detecting abnormal metrological drift when the drift function remains less than or equal to a predetermined threshold for a predetermined duration, and then, starting from a drift time (t.sub.d) and under the effect of abnormal metrological drift, the individual consumption no longer lies in a fifth interval centered on the reference individual consumption.

8. The monitoring method according to claim 7, wherein the drift function is an average of the slopes of segments, each connecting together two successive measurement points, each measurement point having as its coordinates the time at which an individual consumption measurement is taken, and said individual consumption measurement.

9. The monitoring method according to claim 1, wherein the mechanism is a flush.

10. A fluid meter including a measuring device and a processor module arranged to perform the monitoring method according to claim 1.

11. A computer program including instructions for causing the fluid meter according to claim 10 to execute a monitoring method for monitoring a measuring device of a fluid meter that is arranged to produce measurements of the overall consumption of an installation, the method comprising the steps of: analyzing the overall consumption measurements to identify a mechanism in the installation that operates with operating cycles, each presenting a substantially constant cycle duration (t.sub.1−t.sub.0) and during each of which the individual consumption (V.sub.1−V.sub.0) of the mechanism is substantially constant; detecting the operating cycles of the mechanism and measuring the individual consumption of the mechanism for each detected operating cycle; detecting abnormal metrological drift of the measuring device of the fluid meter as a function of variation over time in the individual consumption of the mechanism.

12. A computer readable storage medium having stored thereon the computer program according to claim 11.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0028] Reference is made to the accompanying drawing, in which:

[0029] FIG. 1 shows a graph plotting a curve of measurements of overall consumption in an installation;

[0030] FIG. 2 shows a graph plotting a curve of consumption by an individual flushing system, while abnormal metrological drift is taking place in the water meter.

DETAILED DESCRIPTION OF THE INVENTION

[0031] In this example, the monitoring method of the invention is performed to detect abnormal metrological drift in a measuring device of a water meter.

[0032] The water meter measures the overall water consumption of an installation, e.g. situated in a dwelling.

[0033] In addition to the measuring device, the water meter includes a processor module. The processor module comprises at least one processor component adapted to execute instructions of a program for performing the steps of the monitoring method as described below. By way of example, the processor component may be a processor, a microcontroller, or indeed a programmable logic circuit such as a field programmable gate array (FPGA) or an application-specific integrated circuit (ASIC).

[0034] The invention consists firstly in identifying a particular water-consuming mechanism in the installation by analyzing the overall consumption measurements of the installation as produced by the measuring device of the water meter. This mechanism operates in operating cycles, each of which presents a cycle duration that is substantially constant and during each of which the individual consumption of the mechanism is substantially constant. Thereafter, the invention consists in detecting the operating cycles of that mechanism, and in measuring the individual consumption of the mechanism for each of its detected operating cycles. The invention then consists in detecting the occurrence of abnormal metrological drift when the measurements of the individual consumption drift abnormally over time, even though they ought to be substantially constant, since the individual consumption of the mechanism over each operating cycle is substantially constant.

[0035] It can thus be understood that a distinction is drawn between the overall consumption of the installation as a whole, as measured by the water meter, and the individual consumption of the mechanism, which is measured in a manner described below.

[0036] In this example, the mechanism in question is a flush. Specifically, it is known that a conventional flush typically consumes a substantially constant volume of water, lying in the range 9 liters (L) to 12 L, and that the time taken to refill the tank of a conventional flush is substantially constant and is of the order of a few tens of seconds once the flush has been engaged.

[0037] The monitoring method thus consists firstly in identifying the flush from within the overall consumption measurements made by the water meter.

[0038] To do this, the processor component acquires the overall consumption measurements and then detects a reference operating cycle having a cycle duration and an individual consumption that are respectively substantially equal to a previously-input cycle duration and to a previously-input individual consumption corresponding to a known mechanism, specifically a known type of conventional flush.

[0039] The previously-input cycle duration and the previously-input individual consumption correspond respectively to the above-mentioned time taken to fill the tank of a flush and to the substantially constant volume of water. The term “previously-input” is used to mean that the data is previously obtained and then stored, either in the water meter or else in some other system (a data concentrator, an information system (IS), etc.), in which case the stored data is subsequently acquired by the water meter.

[0040] The processor component of the water meter then associates the flush with a reference cycle duration equal to the duration of the reference operating cycle and with a reference individual consumption equal to the individual consumption of the reference operating cycle. These reference measurements form a reference pair.

[0041] Detecting an operating cycle in the overall consumption measurements, and thus in particular detecting the reference operating cycle, consists in detecting, in the overall consumption of the installation, a succession of a first stable stage, of an increasing stage, and of a second stable stage.

[0042] In the overall consumption measurements of FIG. 1, there can be seen a reference operating cycle 1.

[0043] Detecting the first stable stage 2 and the increasing stage 3 consists in detecting the absence of any overall water consumption in the installation during at least a predetermined duration, followed by a relatively rapid increase in the overall consumption.

[0044] It is therefore sought to identify a time to that satisfies both:

V.sub.0−V′.sub.0≤ΔV.sub.0,

and also:

V′.sub.0−V.sub.0>ΔV′.sub.0,

where V.sub.0 is the overall consumption of the installation up to the time to, V′.sub.0 is the overall consumption up to the time t.sub.0−Δt.sub.0, and V″.sub.0 is the overall consumption up to the time t.sub.0+Δt′.sub.0.

[0045] In this example:

Δt.sub.0=10 seconds (s);
Δt′.sub.0=1 s;

ΔV.SUB.0.=0.1 L;

ΔV′.SUB.0.=0.1 L.

[0046] In this example, the first stable stage 2 thus extends from t.sub.0−10 s to t.sub.0. The increasing stage 3 starts from t.sub.0, i.e. after observing at least 10 seconds of stability in the overall consumption, and it includes the time interval from t.sub.0 to t.sub.0+1 s.

[0047] Detecting the second stable stage 4 then consists once more in detecting stability in the overall water consumption after the increasing stage 3.

[0048] It is therefore sought to identify a time t.sub.1 that satisfies both:

V′.sub.1−V.sub.1≤ΔV.sub.1,

and also:

V.sub.1−V″.sub.1>ΔV′.sub.1,

where V.sub.1 is the overall consumption up to the time t.sub.1, V′.sub.1 is the overall consumption up to the time t.sub.1+Δt.sub.1, and V″.sub.1 is the overall consumption up to the time t.sub.1−Δt′.sub.1.

[0049] In this example:

Δt.sub.1=10 s;
Δt′1=1 s;

ΔV.SUB.1.=0.1 L;

ΔV′1=0.1 L.

[0050] The processor component then calculates the difference between the overall consumption V.sub.1 (corresponding to the consumption up to the second stable stage 4) and the overall consumption V.sub.0 (corresponding to the consumption up to the first stable stage 2), in order to obtain a measurement of the individual consumption in the operating cycle 1. The duration from t.sub.0 to t.sub.1 corresponds to the duration of the operating cycle.

[0051] The processor component then compares the individual consumption V.sub.1−V.sub.0 and the cycle duration t.sub.1−t.sub.0 with the previously-input individual consumption and the previously-input cycle duration.

[0052] In this example, this gives:

V.sub.1−V.sub.0=9.8 L and t.sub.1−t.sub.0=38 s.

[0053] This data is substantially equal to the previously-input data and does indeed correspond to a flush: the operating cycle 1 is indeed a reference operating cycle, defined by a reference cycle duration (t.sub.1−t.sub.0) and by a reference individual consumption (V.sub.1−V.sub.0). The processor component associates the flush with the reference cycle duration and with the reference individual consumption.

[0054] Advantageously, in order to validate and consolidate the reference measurements, provision is made to repeat them several times under similar conditions, e.g. 5 times. The reference measurements are validated if the variations in the reference cycle time and the reference individual consumption are small.

[0055] The symbol t designates the mean of the 5 measured reference cycle durations, and the symbol V designates the mean of the 5 measured reference individual consumptions.

[0056] It is considered that the measurement of the reference cycle duration is confirmed if all 5 measurements lie in a first reference interval centered on t and defined by t±5%.

[0057] It is considered that the measurement of the reference individual consumption is confirmed if all 5 measurements lie in a second reference interval centered on V and defined by V±5%.

[0058] Once the measurements are confirmed, the processor component defines as the “confirmed” reference cycle duration the mean t of the reference cycle durations, and as the “confirmed” reference individual consumption, the mean V of the reference individual consumptions. The processor component associates the reference pair (V,t) with the flush.

[0059] It should be observed that, in the event of there being one or more other mechanisms present, e.g. in the event of a second flush being present, or indeed in the event of the flush having a small flush mechanism and a large flush mechanism, the processor component identifies these other mechanisms in similar manner and associates them in similar manner with their own respective reference cycle durations t and with their own respective reference individual consumptions V.

[0060] As time passes, the processor component then detects “current” operating cycles of the flush, and for each detected operating cycle, it measures the cycle duration and the individual consumption of the flush. These operating cycles are detected in the same manner as the reference operating cycle is detected (detecting the first stable stage, the increasing stage, and the second stable stage). The cycle duration and the individual consumption are also measured in the same manner as the reference cycle duration and the reference individual consumption.

[0061] Detecting operating cycles serves firstly to detect any change of the flush on the basis of any variation in the cycle duration and/or any variation in the individual consumption of the flush.

[0062] A detected change of the flush may correspond either to the flush being replaced by an identical flush (or to the flush being renovated), or else to the flush being replaced by a non-identical flush. The processor component detects these two types of change and distinguishes between them.

[0063] An identical replacement of the flush is detected when, starting from a first change time, the cycle duration no longer lies in a first interval centered on the reference cycle duration and the individual consumption no longer lies in a second interval centered on the reference individual consumption (even though, previously, they used to lie in those intervals).

[0064] A replacement of the flush with a non-identical mechanism is detected when, starting from a second change time, the cycle duration no longer lies in a third interval centered on the reference cycle duration and the individual consumption no longer lies in a fourth interval centered on the reference individual consumption (even though, previously, they used to lie in those intervals). The third interval and the fourth interval are wider than the first interval and the second interval.

[0065] By way of example, the first interval may be defined by t±5%, the second interval by V±5%, the third interval by t±10%, and the fourth interval by V+10%.

[0066] Thus, in the event that, over a certain duration, the cycle duration and the individual consumption are included to within a certain margin respectively in the first interval t±5% and in the second interval V±5%, and then, suddenly, the cycle duration and the individual consumption lie outside the first interval and the second interval, but still within the third interval t±10% and the fourth interval V±10%, the processor component detects that the flush has been replaced identically.

[0067] The processor component then determines a new reference cycle duration t′ and a new reference individual consumption V′ and it replaces the reference pair (V′,t′) with the new reference pair (V′, t′).

[0068] In contrast, in the event that, over a certain duration, the cycle duration and the individual consumption are included to within a certain margin in the first interval t±5% and in the second interval V±5%, and that, suddenly, the cycle duration and the individual consumption lie outside the third interval t±10% and the fourth interval V±10%, the processor component detects that the flush has been replaced by a non-identical flush.

[0069] The processor component then determines a new reference cycle duration t′ and a new reference individual consumption V′ and thus creates the new reference pair (V′, t′) while conserving the existing reference pair (V, t).

[0070] The processor component can thus store one or more reference measurements for a single installation by means of the pairs (V, t) and it can update them in real time.

[0071] Detecting operating cycles also serves to detect abnormal metrological drift of the measuring device of the water meter. When the processor component has determined at least one reference pair (V, t) and when it has stored this reference pair, the water meter goes into a standby mode (which does not prevent it from acting in parallel to find other mechanisms that have not yet been detected, and/or to find changes of the mechanisms that have been identified).

[0072] When the water meter is in standby mode, it attempts to detect abnormal metrological drift from variation in the individual fluid consumption of the flush as obtained from the measurements of overall consumption.

[0073] For each of the identified mechanisms, standby mode consists in measuring once again 5 consecutive periods corresponding to use of that mechanism. This obtains successive pairs, written (V.sub.n,t.sub.n) for a mechanism that has the reference pair (V,t) and which has never been detected as changed by the processor component (identical replacement or replacement by a non-identical mechanism).

[0074] Detecting abnormal metrological drift consists firstly in evaluating a drift function representative of drift in the individual consumption of the flush.

[0075] In this example, the drift function may be as follows:

[00001] $P_{n} = \frac{1}{k} {.Math.}_{i = 0}^{i = k - 1} {\overline{(V}}_{n - 1} - {\overline{V}}_{n - i - 1}) / T_{n - i}$

[0076] where T.sub.n−i is the time that elapses between the measurements V.sub.n−i and V.sub.n−i−1.

[0077] The drift function is thus the average of the slopes of segments, each connecting together two successive measurement points, each measurement point having as its coordinates the time at which an individual consumption measurement is taken and said individual consumption measurement.

[0078] The drift function P.sub.n can be seen in FIG. 2.

[0079] The processor component detects abnormal metrological drift when the print function remains less than or equal to a predetermined threshold during a relatively long predetermined drift duration (thus a slow drift is detected first), and then, starting from a drift time t.sub.d, and under the effect of the drift, the individual consumption no longer lies in a fifth interval 5 centered on the reference individual consumption V.

[0080] Thus, abnormal metrological drift is detected when the drift function P.sub.n is such that:

P.sub.n≤S.sub.d,

assuming that k is great enough for:

Σ.sub.i=0.sup.i=kT.sub.n−i≥D.sub.d,

and that under the effect of the current drift, the individual consumption no longer lies in the fifth interval 5.

[0081] S.sub.d is the predetermined drift threshold, which for example is equal to 0.1 L/month.

[0082] D.sub.d is the predetermined drift duration, e.g. equal to 3 months.

[0083] In this example, the fifth interval 5 is defined as V±5%.

[0084] Advantageously, it is ensured that at least three consecutive values (V.sub.n,V.sub.n+1,V.sub.n+2) of the individual consumption no longer lie in the fifth interval 5 before detecting abnormal metrological drift.

[0085] It should be observed that it is possible to deduce P.sub.n+1 from P.sub.n by the following formula:

[00002] $P_{n + 1} = P_{n} + \frac{1}{k} \times [\frac{\overline{(V_{n + 1}} - \overline{V_{n})}}{T_{n + 1}} - \frac{(\overline{V_{n - k + 1}} - \overline{V_{n - k}})}{T_{n - k + 1}}] .$

[0086] This avoids using the above-described formula for P.sub.n, thereby simplifying calculation and thus simplifying the resources of the processor component used for performing the monitoring method.

[0087] When the water meter has detected abnormal metrological drift, it returns an anomaly message to the Information System.

[0088] Naturally, the invention is not limited to the embodiment described, but covers any variant coming within the ambit of the invention as defined by the claims.

[0089] The invention is not necessarily performed in the fluid meter, and it could be performed in full or in part in one or more other pieces of equipment: a data concentrator, a district meter, a server of the Information System, etc.

[0090] The mechanism used as the reference is not necessarily a flush. It is possible to use any mechanism that operates with operating cycles, each presenting a cycle duration that is substantially constant and during each of which the individual consumption of the mechanism is substantially constant. By way of example, the mechanism could be an automatic sprinkler system.

[0091] The fluid meter may measure the consumption of a fluid that is not necessarily water, but that could be some other liquid, a gas, oil, etc.

DETECTING ABNORMAL METROLOGICAL DRIFT IN A FLUID METER

Inventors

Cpc classification

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G01D4/002

PHYSICS

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G01D3/08

PHYSICS

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Y04S20/30

GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

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G01W1/18

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G01D2204/22

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International classification

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G01W1/18

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G01W1/10

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Abstract

Claims

Description