Supervisory method for automated and autonomous monitoring of asynchronous motor centrifugal pumps

Abstract

The invention relates to a monitoring method for monitoring a centrifugal pump (2), which includes, in particular, a monitoring phase during which the centrifugal pump is determined to be operating in a stable or unstable regime. This determination is based on an analysis of subharmonic amplitudes contained in various sampled signals, which are obtained by sampling measured analog electrical quantities related to the operation of the centrifugal pump. Abstract figure: Figure 1

Description

Title of the invention: Supervisory method for automated and autonomous monitoring of asynchronous motor centrifugal pumps technical field

[0001] The invention relates to a method of supervision.

[0002] It relates more particularly to a supervisory method capable of automatically and autonomously supervising asynchronous motor centrifugal pumps, in particular by being able to control their stability and identify if they exhibit anomalies during their operation.

[0003] The invention also relates to a supervisory system implementing the supervisory method.

[0004] The invention finds a favorite, and not limiting, application in the field of pumping stations using asynchronous motor centrifugal pumps, for example: for water supply, filtration, lifting, drilling, capture, transfer, circulation. Previous technique

[0005] As is known, to determine whether a centrifugal pump with an asynchronous motor is functioning correctly, its flow / pressure curve is analyzed. A flow / pressure curve is defined as the relationship between the discharge pressure of the centrifugal pump and its discharge flow rate. To determine whether a centrifugal pump is functioning correctly, it is useful to determine whether the operating point is located at the center or at the extremes of the flow / pressure curve. In particular, operation at zero flow rate or zero pressure can be destructive.

[0006] A centrifugal pump can exhibit a plurality of malfunctions such as: a malfunction due to an electrical overload, or to a supply that is too low or disturbed; a reverse rotation of the centrifugal pump due to a reversal of the phase order of a three-phase supply; the presence of air bubbles in the pumped liquid fluid; wear of the parts of the centrifugal pump such as the bearings; a loss of prime resulting in the pump running dry; etc.

[0007] Numerous protective devices exist for protecting centrifugal pumps with asynchronous motors, for example, but not limited to: motor-protected circuit breakers that protect against overcurrents and overloads; dry-running protection devices that detect undercurrent or phase shift in response to flow / pressure anomalies related to such dry running; and other devices. positive protection to detect and report cases of reverse rotation, bearing wear; etc.

[0008] Since a motor converts electrical energy into mechanical energy, there is a correlation between its electrical and mechanical behavior. By extrapolation, it is possible to identify abnormal pump operation by analyzing its electrical consumption. Mechanical instability of the pump results in electrical instability. Therefore, variations in electrical quantities mirror the mechanical variations of the asynchronous motor.

[0009] This is why most of these protection devices rely on setting different tripping thresholds associated with observable physical quantities during the operation of the centrifugal pump: for example, its electrical supply voltage, its electrical current intensity. When at least one physical quantity exceeds its associated tripping threshold, a malfunction may be inferred or observed.

[0010] These protection devices, however, have several drawbacks. First, they require manual adjustment by a user of all the trigger thresholds, depending on the pump model. This manual adjustment therefore implies that the user must know precisely the values ​​of these operating thresholds, that is, have a complete understanding of the centrifugal pump's operation in order to know the values ​​of the various physical quantities that will cause malfunctions. In other words, manually setting these trigger thresholds requires a certain level of operator expertise and is also very time-consuming (which impacts the time required to put the centrifugal pump into service). If the trigger thresholds are not set or are set incorrectly, the pump will be inadequately protected.

[0011] Since the functional characteristics of a centrifugal pump can vary depending on the pump model and its installation environment, this means that the tripping thresholds may not be the same. Therefore, an operator would have to repeat the tripping threshold parameterization step if they were to use the same protection device for centrifugal pumps with different model numbers in the same pumping installation, and also for a centrifugal pump installed in a different environment. Summary of the invention

[0012] To this end, the invention proposes a monitoring method capable of autonomously (i.e., without human intervention) and automatically monitoring a centrifugal pump with an asynchronous motor. The monitoring method is advantageously capable of: - to establish the operating regime of the centrifugal pump, - to determine the conditions that could lead to different types of malfunction, and therefore to determine when said malfunctions occur; - to intervene on the control of the centrifugal pump in case of malfunction.

[0013] Another advantage of the supervision method of the invention is that it is universal, that is to say that it is applicable to all types of centrifugal pump reference, again without requiring human intervention in its implementation.

[0014] Thus, the invention relates to a supervisory method for supervising a centrifugal pump driven by an asynchronous motor and operating at a power supply frequency; the supervisory method comprising a start-up step during which the centrifugal pump is started, this start-up step being followed by a supervisory phase comprising an iteration of a set of steps, said set of steps comprising at least: - a measurement step during which three analog electrical quantities are measured which correspond to: a supply voltage of the centrifugal pump which can reach a reference alternating voltage, an electric current intensity in the centrifugal pump, and a phase shift between the supply voltage and the electric current intensity; - a signal sampling step during which a mathematical function is applied to sample each of the three analog electrical quantities according to a sampling frequency, and at the end of which three sampled signals are obtained respectively associated with the three analog electrical quantities, in which each of the three sampled signals is represented in a frequency spectrum and includes a fundamental line at a fundamental frequency equal to the power supply network frequency, at least one subharmonic, and at least one harmonic; - a comparison step during which, for each of the three sampled signals, an amplitude of at least one subharmonic is compared to a stability threshold, such that the centrifugal pump is determined to be operating in an unstable operating regime if the amplitude of at least one subharmonic of at least one of the three sampled signals is greater than or equal to the stability threshold associated with it, and determined to be operating in a stable operating regime if the amplitude of at least one subharmonic of the three sampled signals is less than its respective stability threshold.

[0015] The iterative implementation of the measurement, signal sampling and comparison steps included in the monitoring phase of the monitoring process advantageously makes it possible to determine at any time the operating regime of a The monitoring process for a centrifugal pump determines whether it is operating in a stable or unstable mode. This process allows for the detection of when a centrifugal pump might switch from a stable to an unstable operating mode.

[0016] As stated above, the operating regime of a centrifugal pump is determined by analyzing sampled signals relating to three analog physical quantities on which the active power of the centrifugal pump depends (i.e., the electrical power it absorbs), and which correspond to: - the supply voltage of the centrifugal pump, which can reach a reference alternating voltage that corresponds to a maximum supply voltage suitable for being supplied by a power source (for example, the electrical network, a generator set) of the centrifugal pump; - the intensity of the electric current in the centrifugal pump; and - the phase shift between the supply voltage and the electric current intensity.

[0017] The signals corresponding to the three analog physical quantities before sampling are measured at the centrifugal pump using measuring devices designed to measure electrical voltages, and / or electrical current intensities, and / or phase shifts between electrical voltages and electrical current intensities.

[0018] The signals of the three analog physical quantities are sampled over a frequency spectrum using a mathematical function designed to sample analog signals (for example, the Fast Fourier Transform, FFT) at a sampling frequency that is synchronized to a power grid frequency (which power grid frequency may be 50 Hz or 60 Hz) and that conforms to the Shannon criterion. The sampled signal for each analog physical quantity includes a fundamental frequency at a fundamental frequency equal to the power grid frequency, at least one harmonic at a frequency equal to a multiple of the fundamental frequency, and at least one subharmonic at a frequency equal to a submultiple of the fundamental frequency.

[0019] During the comparison step, the amplitude of at least one subharmonic of each sampled signal is compared to a stability threshold specific to that sampled signal (and therefore to the analog physical quantity to which it relates). In other words, three stability thresholds are considered (one per sampled signal). If at least one subharmonic of a sampled signal comprises several subharmonics, then the amplitudes of the several subharmonics are compared to the stability threshold associated with the sampled signal.

[0020] The centrifugal pump is determined to operate in a operating regime Stable operation is indicated if it is verified that, for each of the three sampled signals, at least one subharmonic is below the stability threshold. Otherwise, if at least one subharmonic of at least one of the three sampled signals is greater than or equal to the stability threshold, then the centrifugal pump is operating in an unstable regime.

[0021] According to one embodiment of the invention, the supervision phase includes an acquisition step for the purpose of acquiring / storing the sampled signals associated with the three physical quantities.

[0022] According to one feature of the invention, the set of steps also includes a verification step implemented following the comparison step during which it is verified, for each of the three sampled signals, whether:

[0023] - an amplitude of the fundamental line is included in a first range of amplitude tolerance bounded by a first excluded maximum amplitude and a first excluded minimum amplitude; and

[0024] - the amplitude of at least one subharmonic is contained within at least one a second amplitude tolerance range bounded by a second excluded amplitude maximum and a second excluded amplitude minimum; and

[0025] - an amplitude of at least one harmonic is contained within at least one third amplitude tolerance range bounded by a third excluded amplitude maximum and a third excluded amplitude minimum;

[0026] and wherein said verification step is followed by a determination step during which it is determined whether or not the centrifugal pump has at least one malfunction based on at least the results of the verification step.

[0027] Advantageously, through the implementation of the determination step in the monitoring phase, the monitoring method is able to determine whether at least one malfunction occurs during the operation of a centrifugal pump. If so, at least one malfunction may cause the centrifugal pump to switch from a stable operating regime to an unstable operating regime.

[0028] In addition, at least one malfunction can be determined by the monitoring method during a verification step taking place before the determination step, and during which it is verified, for each of the three sampled signals, whether the amplitudes of the fundamental line, of at least one harmonic, and of at least one subharmonic are within or not within amplitude tolerance ranges.

[0029] According to a feature of the invention, for each of the three sampled signals, at the start-up of the centrifugal pump, during the start-up step, the first maximum amplitude, the first minimum amplitude, the second maximum of amplitude, the second minimum of amplitude, the third maximum of amplitude, and the third minimum of amplitude are initialized to zero values; and in which the set of steps also includes an update step provided that the centrifugal pump is operating in the stable operating regime; and during which, for each of the three sampled signals: - the first maximum amplitude and the first minimum amplitude become respectively equal to a minimum amplitude and a maximum amplitude of the amplitude of the fundamental line; - the second maximum amplitude and the second minimum amplitude become respectively equal to a minimum amplitude and a maximum amplitude of the amplitude of at least one subharmonic; - the third maximum amplitude and the third minimum amplitude become respectively equal to a minimum amplitude and a maximum amplitude of the amplitude of at least one harmonic.

[0030] In other words, the amplitude maxima and amplitude minima defining the amplitude tolerance ranges associated with the fundamental frequency, at least one harmonic, and at least one subharmonic of each of the three sampled signals are not predefined and fixed values. The amplitude maxima and amplitude minima of the amplitude tolerance ranges are initially initialized to zero when the centrifugal pump starts.They are then, during the supervision phase, automatically updated by the supervision process when, at a time t, it is detected that the centrifugal pump is operating in a stable operating regime and that it does not present any malfunction, so that, for the three sampled signals, the maxima and minima of the amplitude of the amplitude tolerance ranges associated respectively with the fundamental line, with at least one harmonic, and with at least one subharmonic, correspond to the maximum and minimum of the amplitude of the fundamental line, the at least one harmonic, and the at least one subharmonic at said time t.

[0031] The maximum and minimum amplitude values ​​of the amplitude tolerance ranges depend on the functional characteristics of a centrifugal pump. Since these are not predefined in the monitoring method, the latter is advantageously, as indicated above, applicable to all types of centrifugal pump references.

[0032] Since the amplitude maxima and amplitude minima of the amplitude tolerance ranges are determined automatically, they do not have to be provided to the supervisory process by a centrifugal pump operator; meaning that said operator does not need to have knowledge of said amplitude maxima and amplitude minima either.

[0033] According to a feature of the invention, a confidence index is defined such that: - it is initialized to zero when the centrifugal pump is started during the start-up step; - it is incremented following the verification step when it is verified that the amplitudes of the fundamental line, of at least one subharmonic, and of at least one harmonic for each of the three sampled signals are respectively within the first amplitude tolerance range, within at least one second amplitude tolerance range, and within at least one third amplitude tolerance range; - remains constant when at least one malfunction (DI; D2) is detected during the determination step (DET); - is decremented when at least one malfunction (DI; D2) is detected during the determination step (DET), and if: the supply voltage approaches a reference supply signal, or the phase shift is substantially equal to zero.

[0034] According to a feature of the invention, following the determination step, and in the event that the confidence index becomes negative, the first maximum amplitude, the first minimum amplitude, the second maximum amplitude, the second minimum amplitude, the third maximum amplitude and the third minimum amplitude are reset to zero values ​​for each of the three sampled signals.

[0035] Advantageously, the confidence index responds positively to a problem of possible non-determination of a malfunction occurring at the very moment of the start of the centrifugal pump (in other words, during a commissioning of the centrifugal pump in a fault situation), due to the nature of said malfunction, since for each of the three sampled signals El, the minima and maxima of amplitude of the tolerance ranges of the fundamental line, of at least one subharmonic, and of at least one harmonic, are initialized to zero at the start of the centrifugal pump.

[0036] The confidence index also prevents the occurrence and persistence of a worst-case application situation in which: the malfunction during the commissioning of the centrifugal pump is not determined, and the centrifugal pump operates in a stable operating regime. Indeed, in such an application situation, the monitoring process, in the update step of an implementation of the step set that directly follows the start-up step, would update the amplitude maxima and minima of the different tolerance ranges with erroneous values, which would then be used as the starting reference for subsequent implementations of the step set (more precisely, the verification and determination steps), resulting in errors in the monitoring of the centrifugal pump.

[0037] The confidence index value changes during the monitoring phase as the verification and determination steps are implemented, as described above. A high confidence index means that during the monitoring phase of the centrifugal pump, few or no malfunctions occurred, with the centrifugal pump operating under nominal conditions; the amplitudes of the fundamental frequency, at least one subharmonic, and at least one harmonic being within their respective amplitude tolerance ranges.

[0038] Conversely, a low confidence index can result in the occurrence of several malfunctions, whether the centrifugal pump is operating in a stable or unstable regime. The confidence index is notably decreased when a malfunction is detected during the determination phase, while the centrifugal pump is operating in a stable regime and the supply voltage is approaching a reference supply signal, or the phase shift is tending towards zero (i.e., it is approaching zero, without actually being zero).

[0039] When the confidence index becomes negative, the amplitude maxima and amplitude minima of the different amplitude tolerance ranges are reset because it is then certain that they are erroneous.

[0040] According to one embodiment of the invention, the reference supply signal is a sinusoid with a frequency equal to the supply network frequency and an amplitude equal to the reference AC voltage.

[0041] According to a feature of the invention, during the determination step, at least one malfunction is determined when, for at least one of the three sampled signals, at least: - the amplitude of the fundamental line is not within the first amplitude tolerance range, or - the amplitude of at least one subharmonic is not included within at least one second amplitude tolerance range, or - the amplitude of at least one harmonic is not included in at least one third amplitude tolerance range.

[0042] In other words, and as mentioned previously, during the determination step, based on the results of the verification step, the monitoring method is advantageously suited to detect malfunctions and determine their nature. Malfunctions are detected and identified, in particular, according to whether the amplitudes of the fundamental frequency, at least one subharmonic, and at least one harmonic, for each of the three sampled signals, are within their respective amplitude tolerance ranges.

[0043] According to a feature of the invention, at least one malfunction is determined to be an overload, and is detected when, for the sampled signal associated with the electric current intensity, the amplitude of the fundamental line becomes greater than kl times the first amplitude maximum, kl being a coefficient strictly greater than 1.

[0044] According to one embodiment of the invention, the coefficient kl is between 1.2 and 1.5.

[0045] Advantageously, the monitoring method is capable, if it determines that the centrifugal pump has a malfunction, of identifying the latter as an overcurrent / overload phenomenon, which is characterized by an exceedance of the amplitude of the fundamental line of the sampled signal associated with the electric current intensity by more than 20% of the first maximum amplitude of the tolerance range relative to said fundamental line.

[0046] According to one feature of the invention, at least one malfunction is determined to be a loss of prime resulting in the centrifugal pump running dry when: - for the sampled signal associated with the electric current intensity, the amplitude of the fundamental line becomes less than k2 times the first amplitude minimum of the first amplitude tolerance range, k2 being a coefficient strictly less than 1; and: - for the sampled signal associated with the phase shift, the amplitude of the fundamental line becomes greater than the first amplitude maximum.

[0047] According to one embodiment of the invention, the coefficient k2 is between 0.70 and 0.98.

[0048] Advantageously, the monitoring method is capable of detecting, during the operation of a centrifugal pump, the priming phenomena, which are reflected: temporally, by a drop in the electrical current intensity below a nominal value and an increase in the phase shift value, and frequency-wise, as described above.

[0049] According to a feature of the invention, during the determination step, at least one malfunction is determined at least as a function of a number of harmonics contained in each of the three sampled signals.

[0050] According to a feature of the invention, at least one malfunction is determined to be an abnormal vibration of the centrifugal pump when, for at least one of the three sampled signals, the number of harmonics it contains during at least one second execution of the step sequence becomes greater than the number of harmonics it contained during at least one first execution of the step sequence that temporally precedes said at least one second implementation.

[0051] In other words, certain malfunctions are advantageously determined by the monitoring process when, for each of the three sampled signals, the number of harmonics they contain during an implementation of the set of steps is compared with the number of harmonics they contained during the previous implementation.

[0052] The monitoring method is particularly capable of detecting abnormal vibrations of the centrifugal pump which may, but are not limited to, be caused by defective bearings, the presence of air bubbles in the pumped fluid (which can cause cavitation), etc. These vibrations are detected by the monitoring method when the number of harmonics of one of the three sampled signals increases between two successive implementations of the set of steps.

[0053] According to a feature of the invention, at least one malfunction is determined to be a disturbance of the power supply signal when, for the sampled signal associated with the supply voltage when: - the number of harmonics it includes during at least one second implementation of the set of steps becomes greater than the number of harmonics it contained during at least one first implementation of the set of steps temporally preceding said at least one second implementation, with at least one additional harmonic counted in addition to the at least one harmonic; and - that an amplitude of the at least one additional harmonic is at least greater than k3 times the reference alternating voltage, k3 being a coefficient strictly greater than 1.

[0054] According to one embodiment of the invention, the coefficient k3 is between 1.1 and 1.5.

[0055] The monitoring method is also advantageously suited to detect disturbances in the power supply signal, which may be short-lived or permanent, and which may be caused by interference from equipment external to the power source but connected to the same electrical network. These disturbances are detected by the monitoring method when the number of harmonics in the sampled signal relative to the supply voltage increases between two successive implementations of the set of steps, and the amplitude of at least one new harmonic is k3 times the reference AC voltage.

[0056] According to a feature of the invention, wherein, during the determination step, at least one malfunction is determined to be a reversal of the direction of rotation of the centrifugal pump when a phase shift difference between the phase shifts measured during the measurement step, during two successive implementations of the set of steps, becomes equal to or greater than a critical value of phase shift.

[0057] According to one embodiment of the invention, the critical phase shift value is between 30° and 120°.

[0058] Advantageously, the monitoring method is capable of determining whether the malfunction exhibited by the centrifugal pump is a reversal of its direction of rotation. Such a phenomenon can occur if the centrifugal pump is powered by a three-phase power supply and the phase sequence of this power supply is accidentally reversed.

[0059] When a reversal of the direction of rotation occurs, a phase shift difference of between 30° and 120° is observed between two successive phase shift measurements.

[0060] According to one feature of the invention, the set of steps includes a categorization step which is implemented after the determination step if, during the latter, it is determined that the centrifugal pump has at least one malfunction, and during which said at least one malfunction is categorized as being: - a minor defect, with the centrifugal pump controlled to continue operating following said categorization step; - a major defect, with the centrifugal pump being ordered to be temporarily stopped during a temporary shutdown time following the categorization step, then restarted once the temporary shutdown time has elapsed; - a critical fault, with the centrifugal pump controlled for shutdown following the categorization step.

[0061] In other words, if the monitoring process determines that the centrifugal pump has at least one malfunction during the determination step of an implementation of the set of steps, a categorization step is performed following the determination step for that implementation. The categorization step consists of categorizing the at least one identified malfunction as a minor, major, or critical fault, depending on its nature. Depending on the at least one identified and categorized fault, the centrifugal pump may continue to operate, be temporarily stopped before restarting, or be shut down.

[0062] According to a feature of the invention, at least one malfunction, if it is categorized as a minor defect, respectively a major defect, during at least one first implementation of the set of steps, is categorized as a major defect, respectively a critical defect, during at least one second implementation of the set of steps taking place temporally after at least one first implementation.

[0063] In other words, when a malfunction is identified by the supervisory process during a determination step, and is categorized as A minor or major defect's severity level can change from minor to major, or from major to critical, if the same malfunction is identified multiple times during subsequent implementations of the set of steps (and therefore the determination step). This escalation depends on the number of times the malfunction is identified, regardless of whether it is detected during implementations that are sequential or not. For example: - in a given application context, the malfunction can be identified for implementation n of the set of steps, implementation n+1, implementation n+2; whereas - in another application context, the same malfunction is identified for an implementation n of the set of steps and an implementation n+2, but not detected during the implementation n+1.

[0064] According to one embodiment of the invention, for each of the three sampled signals, the stability threshold associated with at least one subharmonic is equal to the amplitude of the fundamental line multiplied by a coefficient k4 representative of a frequency of at least one subharmonic.

[0065] According to one embodiment of the invention, the coefficient k4 is between 0.01 and 0.5.

[0066] According to one feature of the invention, for each of the three sampled signals, at least one subharmonic comprises: - a first subharmonic at a first subharmonic frequency which is, for example, equal to the fundamental frequency divided by two; - a second subharmonic at a second subharmonic frequency which is, for example, equal to the fundamental frequency divided by four; and - a third subharmonic at a third subharmonic frequency which is for example equal to the fundamental frequency divided by eight.

[0067] According to one feature of the invention, for each of the three sampled signals, at least one harmonic comprises: - a first harmonic at a first harmonic frequency which is, for example, equal to the fundamental frequency multiplied by two; - a second harmonic at a second harmonic frequency which is, for example, equal to the fundamental frequency multiplied by four; and - a third harmonic at a third harmonic frequency which is for example equal to the fundamental frequency multiplied by eight.

[0068] According to one embodiment of the invention, the sampling frequency is between 500 Hz and 1 MHz.

[0069] According to one embodiment of the invention, the frequency spectrum is between 0.1 Hz and 100 kHz.

[0070] In a particular embodiment of the invention, the sampling frequency is equal to 1 kHz

[0071] In a particular embodiment of the invention, the frequency spectrum is between 0.1 Hz and 250 Hz.

[0072] According to one embodiment of the invention, the reference voltage is equal to 230 VAC, or 400 VAC.

[0073] The invention also relates to a supervisory system for monitoring a centrifugal pump driven by an asynchronous motor and operating at a mains power frequency, which supervisory system being at least in communication with the centrifugal pump, and comprising: - at least one measuring system configured to measure at least one of three analog electrical quantities corresponding to: a supply voltage of the centrifugal pump capable of reaching a reference AC voltage, an electric current intensity in the centrifugal pump, and a phase shift between the supply voltage and the electric current intensity; and - at least one control unit in communication with the measurement system; said control unit comprising a memory, and a processor which is configured to execute a program for an implementation of the supervisory process as previously described. Brief description of the drawings

[0074] Other features and advantages of the present invention will become apparent from the following detailed description of a non-limiting example of implementation, made with reference to the accompanying figures in which:

[0075] [Fig-1] is a schematic view of a supervisory system for monitoring the centrifugal pump operation; the supervisory system implementing the supervisory process;

[0076] [Fig.2] is a schematic view of a centrifugal pump;

[0077] [Fig.3] is a diagram of the operation of the supervisory process;

[0078] [Fig.4] is a flow diagram of a set of steps implemented iteratively in a supervisory phase that includes the supervisory process;

[0079] [Fig.5] is an illustration of an analog electrical quantity, which corresponds to an electric current intensity, relative to the operation of the centrifugal pump which is measured during a measurement step included in a supervision phase which includes the supervision process (a); and its associated sampled signal obtained following the implementation of a sampling step also included in the supervision phase;

[0080] [Fig.6] is an illustration of a malfunction of the centrifugal pump corresponding to an overload phenomenon (a), which overload is determined / detected by the monitoring method when the fundamental line of the sampled signal relating to the electric current intensity becomes greater than kl times a first maximum amplitude binding / delimiting a first amplitude tolerance range for this fundamental line (b);

[0081] [Fig.7] is an illustration of one of the two conditions under which a malfunction of the centrifugal pump corresponding to a loss of prime is observed (a), this condition being detected by the supervisory system when the fundamental line of the sampled signal relating to the electric current intensity becomes less than k2 times a first minimum of amplitude binding / delimiting the first amplitude tolerance range associated with the fundamental line (b);

[0082] [Fig.8] is an illustration of the other of the two conditions under which a malfunction of the centrifugal pump corresponding to a loss-of-priming phenomenon is observed (a), this condition being detected by the supervisory system when the fundamental line of a sampled signal relating to a phase shift between a supply voltage of the centrifugal pump and the electric current intensity becomes greater than k2' times a first maximum amplitude binding / delimiting a first amplitude tolerance range associated with the fundamental line of this sampled signal (b).

[0083] [Detailed description of one or more embodiments of the invention]

[0084] The invention relates to a supervision method 100 capable of supervising, autonomously (i.e. without human intervention) and automatically, the operation of a centrifugal pump 2 which is, for example, immersed in a tank 20.

[0085] In one embodiment of the invention, with reference to [Fig.1], it is conceivable that the supervision method 100 is capable of supervising in parallel the operation of several centrifugal pumps 2.

[0086] The remainder of the description focuses on the supervision of a single centrifugal pump 2.

[0087] Conventionally, with reference to [Fig. 2], the centrifugal pump comprises a turbine 24 located inside a pump body 25 and which is driven in rotation by a transmission shaft 23 coupled to the rotor 210 of an asynchronous motor 21 (or induction motor), which rotor is contained within a stator 211. The asynchronous motor 21 is configured to convert electrical energy into mechanical energy, rotating the rotor 210, which will cause the rotation of the transmission shaft 23 and therefore of the turbine 25, thus enabling the suction and then the discharge of a fluid by the hydraulic part of the centrifugal pump 2 (and corresponding to the pump body 25).

[0088] Advantageously, the supervision method 100 is universal, that is to say that it is capable of supervising all types of centrifugal pump reference 2. In other words, it is equally applicable to centrifugal pumps 2 operating in single phase as to centrifugal pumps 2 operating in three phase.

[0089] The invention also relates to at least one supervisory system 1 in communication with the centrifugal pump 2. The supervisory system comprises: - a measuring system 3, the role of which is specified below, and which, in the embodiment of the invention described, corresponds to an electrical panel, - a control unit 4 in communication with the measuring system 4 and the centrifugal pump 2, which includes a memory, as well as a processor configured to execute a program containing a list of instructions for the implementation of the supervisory process 100.

[0090] The monitoring method 100 is designed to, during the operation of the centrifugal pump 2: - on the one hand, to establish its operating procedures; and - on the other hand, to determine / detect if malfunctions occur.

[0091] The monitoring process 100 includes a start-up step STA during which the centrifugal pump 2 is started, followed by a monitoring phase SP comprising a set of POS steps implemented iteratively. The monitoring phase SP ends following the shutdown of the centrifugal pump 2 during a shutdown step OVR.

[0092] The POS sequence of steps includes a measurement step MS during which the measurement system 3 measures three analog electrical quantities I, Phi which correspond to: - a supply voltage for the centrifugal pump 2 that can reach a reference AC voltage. For centrifugal pumps operating on single-phase power, the reference AC voltage is 230 VAC. For centrifugal pumps operating on three-phase power, the reference AC voltage is either 400 VAC if the electrical network supplying the centrifugal pump 2 is three-phase 400 VAC (3*400 VAC), or 230 VAC if the electrical network supplying the centrifugal pump 2 is three-phase 230 VAC (3*230 VAC). - an electric current intensity I in the centrifugal pump 2; and - a phase shift Phi observed between the supply voltage and the electric current intensity I.

[0093] In another embodiment, it is conceivable that each of the three analog electrical quantities I, Phi is measured by a measuring device such as a sensor shaped to measure said analog electrical quantity I, Phi (for example, a voltage sensor, a current sensor, etc.).

[0094] The MS measurement step is followed by a signal sampling step NSS during which the analog signals Al of the three analog electrical quantities I, Phi are sampled on a frequency spectrum by means of a mathematical function shaped to sample the analog signals (for example, the Fast Fourier Transform, FFT) at a sampling frequency: which is synchronized with the power supply frequency at which the centrifugal pump 2 operates; and which conforms to the Shannon criterion.

[0095] Within the framework of the invention, the sampling frequency can be between 500 Hz and 1 MHz.

[0096] In the described embodiment, the sampling frequency is considered to be equal to 1 kHz. The power supply frequency is considered to be equal to 50 Hz (in another embodiment, the power supply frequency is equal to 60 Hz).

[0097] At the end of the NSS signal sampling step, a sampled signal El is obtained for each of the three analog electrical quantities I, Phi.

[0098] Each of the sampled signals El includes a fundamental line ROI, R02 at a fundamental frequency FOI, F02 corresponding to the power grid frequency; at least one subharmonic SH11, SH21 whose frequency is a submultiple of the fundamental frequency FOI, F02, and at least one harmonic H11, H21, H31, H41 whose frequency is a multiple of the fundamental frequency FOI, F02.

[0099] In one embodiment of the invention, for each of the three sampled signals El, at least one subharmonic SH11, SH21 comprises:

[0100] - a first subharmonic SH11 at a first subharmonic frequency FSH11 which is for example equal to the fundamental frequency FOI, F02 divided by two;

[0101] - a second subharmonic at a second subharmonic frequency which is for example, equal to the fundamental frequency FOI, F02 divided by four; and

[0102] - a third subharmonic at a third subharmonic frequency which is for example equal to the fundamental frequency FOI, F02 divided by eight.

[0103] For each of the three sampled signals El, at least one harmonic H11, H21, H31, H34 may include:

[0104] - a first harmonic H11 at a first harmonic frequency FH11 which is for example equal to the fundamental frequency FOI; F02 multiplied by two;

[0105] - a second harmonic H31 at a second harmonic frequency FH31 which is for example, equal to the fundamental frequency FOI, F02 multiplied by four; and

[0106] - a third harmonic H41 at a third harmonic frequency FH41 which is for example equal to the fundamental frequency FOI, F02 multiplied by eight.

[0107] Figures 5-a and 5-b illustrate, respectively, for the electric current intensity I of a single-phase centrifugal pump 2, an example of an analog signal Al measured during the measurement step MS, and the sampled signal El obtained from this analog signal following the signal sampling step NSS. In this example, the sampled signal El comprises: - the fundamental ROI line at a fundamental FOI frequency of 50 Hz, - two subharmonics SH11, SH21 respectively at subharmonic frequencies FSH11, FSH21 of 25 Hz and 16.67 Hz (in other words at frequencies equal to F01 / 2 and F01 / 3), - a plurality of harmonics comprising four harmonics H11, H21, H31, H41 at harmonic frequencies FH11, FH21, FH31, FH41 equal to 100 Hz, 150 Hz, 200 Hz, and 400 Hz (or at frequencies equal to F01*2, F01*3, F01*4, F01*8).

[0108] The amplitudes of the fundamental line F01, of the subharmonics SH11, SH21 and of the harmonics H11, H21, H31, H41 are in amperes, since the analog electrical quantity considered is the electric current intensity I.

[0109] Generally, the behavior and / or operating state of a centrifugal pump 2 can be analyzed by the presence of SH11, SH21 subharmonics or FH11, FH21, FH31, FH41 harmonics at specific frequencies. In particular, the following are distinguished: - subharmonics and harmonics reflecting nominal behavior of the centrifugal pump, such as the subharmonic SH21 found at the subharmonic frequency FSH21 equal to F01 / 3 and which is an indicator of a rotation speed of the rotor 2101, particularly in the case of centrifugal pumps 2 operating in single phase; or the subharmonic SH11 found at the subharmonic frequency FSH11 equal to F01 / 2 which can be an indicator of mechanical / electrical stability or instability of the centrifugal pump 2; - the H21, H31 harmonics due to distortions that can occur at the transmission shaft 23 (for example due to wear of bearings 230) or the hydraulic part (for example due to an imbalance of a turbine blade 24; - subharmonics and harmonics resulting from electrical noise, this noise being caused by random variations or fluctuations in the power supply of the asynchronous motor 21, resulting from factors such as electromagnetic interference, electrical switches or other electrical equipment connected to the same electrical network.

[0110] The POS sequence of steps includes, following the NSS signal sampling step, an AQS acquisition step during which the sampled signals El of the three analog electrical quantities I, Phi are recorded / stored in the memory of the control unit 4. They are therefore stored in memory for each of the sampled signals El the frequencies FOI, F02, FSH11, FSH21, FH11, FH21, FH31, FH41 and the amplitudes IRO, PhiR02 of their fundamental line ROI, R02; of their at least one subharmonic SH11, SH21; and of their at least one harmonic H11, H21, H31, H41.

[0111] As a supervision phase SP can include several implementations of the signal sampling step NSS, the set of sampled signals El obtained following each of said implementations are stored in memory.

[0112] Following the NSS signal sampling step, a CMP comparison step is also implemented during which the amplitude of at least one subharmonic SH11, SH21 of each sampled signal El is compared to a stability threshold specific to said sampled signal El (and therefore to the analog physical quantity I, Phi to which it relates). In other words, three stability thresholds are considered (one per sampled signal El). If the at least one subharmonic SH11, SH21 of a sampled signal comprises several subharmonics (as in the case of the example given [Fig. 5]), then the amplitudes of the several subharmonics SH11, SH21 are compared to the stability threshold associated with the sampled signal El.The centrifugal pump 2 is determined to be operating in a stable OK2 regime if it is verified that, for each of the three sampled signals El, at least one SH11, SH21 subharmonic is below the stability threshold. Otherwise, if at least one SH11, SH21 subharmonic of at least one of the three sampled signals El is greater than or equal to the stability threshold, then the centrifugal pump 2 is operating in an unstable NOK2 regime.

[0113] In one embodiment of the invention, the stability threshold associated with at least one subharmonic SH11, SH21 is equal to the amplitude IR01, PhiR02 of the fundamental line ROI, R02 multiplied by a coefficient k4 whose value: is between 0.01 and 0.5; and depends on the subharmonic frequency FHSH11, FSH21 at which at least one subharmonic SH11, SH21 is found.

[0114] The iterative implementation of the MS measurement, NSS signal sampling and CMP comparison steps advantageously allows the OK2, NOK2 operating regime of the centrifugal pump 2 to be determined at any time, and consequently the moment when it can switch from a stable OK2 operating regime to an unstable NOK2 operating regime.

[0115] The CMP comparison step is followed by a DET determination step during which it is capable of detecting / determining whether one or more malfunctions D1, D2 occur during the implementation of the POS step assembly. The SP supervision phase comprises a plurality of successive implementations of the POS step assembly taking place throughout the operation of the centrifugal pump 2, therefore this means that the supervision process 100 is capable of detect a plurality of malfunctions D1, D2 that may occur between the start-up and stop-down of the centrifugal pump 2.

[0116] Possibly, at least one malfunction D1, D2 can cause the centrifugal pump 2 to switch from the stable operating regime OK2 to the unstable operating regime NOK2.

[0117] The detection / determination of certain malfunctions D1, D2 is based at least on an analysis by the supervisory process 100 of the amplitudes IR01, PhiR02 of the fundamental line ROI, R02, of Eau less a subharmonic SH11, SH21, and of at least one harmonic H11, H21, H31, H41 composing each sampled signal El.

[0118] Thus, following the CMP comparison step, and prior to the DET determination step, a CHE verification step is implemented during which it is verified for each of the three sampled signals El, whether:

[0119] - the amplitude IR01, PhiR02 of the fundamental line ROI, R02 is contained within a first tolerance range of amplitude PI 1, P12 bounded by a first maximum amplitude Maxl 1, Max 12 excluded and a first minimum amplitude min 1, min 12 excluded; and

[0120] - the amplitude of at least one subharmonic SH11, SH21 is contained within minus a second amplitude tolerance range bounded by a second excluded amplitude maximum and a second excluded amplitude minimum; and

[0121] - the amplitude of at least one harmonic H11, H21, H31, H41 is contained in at least a third amplitude tolerance range bounded by a third excluded amplitude maximum and a third excluded amplitude minimum.

[0122] The first maximum amplitude Maxl 1, Max 12, the first minimum amplitude minl1, minl2, the second maximum amplitude, the second minimum amplitude, the third maximum amplitude, and the third minimum amplitude are defined as follows: - they are initialized to zero values ​​at the start of the centrifugal pump, - during an implementation of the entire POS step set, they are updated during an update step MAJ following the determination step DET when no malfunction of the centrifugal pump 2 has been detected / determined, and the centrifugal pump 2 is operating in the stable operating regime OK2.

[0123] Regarding the second point, the updates are carried out such that, during the implementation of the entire set of POS steps: - the first maximum amplitude Maxl 1, Max 12 and the first minimum amplitude minl 1, minl2 become respectively equal to a minimum amplitude and a maximum amplitude of the amplitude IR0, PhiR02 of the fundamental line damentale ROI, R02; - the second maximum amplitude and the second minimum amplitude become respectively equal to a minimum amplitude and a maximum amplitude of the amplitude of at least one subharmonic SH11, SH21;

[0124] - the third maximum amplitude and the third minimum amplitude of come respectively equal to a minimum amplitude and a maximum amplitude of the amplitude of at least one harmonic H11, H21, H31, H41.

[0125] In other words, the values ​​of the different maxima of amplitude Maxl 1, Maxl2 and minima of amplitude minll, minl2 updated during an implementation of index jR (j belonging to [1 ; n-1]) of the set of POS steps will serve as reference values ​​during the verification step of the next implementation of index (j+l)R of the set of POS steps.

[0126] The update step is implemented provided that the centrifugal pump is operating in the stable OK2 operating regime. In other words, the maxima of amplitude Maxl 1, Max 12 and minima of amplitude min 1, min 12 are not updated during an implementation of index jR of the POS step set if the centrifugal pump 2 is operating in the unstable NOK2 operating regime during said implementation of index jR, and do not serve as reference values ​​during the verification step CHE of the following implementation of index (j+l)R of the POS step set.Optionally, for example, the maximum amplitudes Maxl 1, Max 12 and minimum amplitudes min 1, min 12 memorized during an implementation of index (jl)R of the POS step set, if the centrifugal pump 2 operated in the stable operating regime OK2 during said implementation of index (jl)R of the POS step set, will serve as reference values ​​during the verification step of the next implementation of index (j+l)R of the POS step set.

[0127] The values ​​of the different maxima of amplitude Maxl 1, Maxl2 and minima of amplitude min 1, minl2 during the different implementations of the set of POS steps are recorded and stored in the memory of the control unit 4.

[0128] The values ​​of the various maximum amplitudes Maxl 1, Maxl 2 and minimum amplitudes min 1, min 12 depend on the functional characteristics of the centrifugal pump 2. As they are not predefined in the supervisory process 100, the latter is advantageously applicable to all types of centrifugal pump references operating in single-phase or three-phase. Since the maximum amplitudes Maxl 1, Max 12 and the minimum amplitudes min 1, min 12 of the amplitude tolerance ranges P1, P12 are determined automatically, they do not have to be provided to the supervisory process 100 by an operator of the centrifugal pump 2; meaning that said operator does not need to possess detailed knowledge of the operation of the centrifugal pump 2 and of these maximum amplitudes Maxl 1, Max 12 and minimum amplitude min 1, min 12.

[0129] The supervision method 100 includes the definition of a confidence index cfi such that: - it is initialized to zero when the centrifugal pump 2 is started during the STA start-up step;

[0130] - it is incremented following the CHE verification step of an IR, 2R implementation, ..., nR of the POS step set when it is verified that the amplitudes IR01, PhiR02 of the fundamental line ROI, R02, of at least one subharmonic SH11, SH21, and of at least one harmonic H11, H21, H31, H41 for each of the three sampled signals El are respectively within the first amplitude tolerance range Pli, P12, within at least one second amplitude tolerance range, and within at least one third amplitude tolerance range;

[0131] - it is decremented when at least one malfunction D1, D2 is detected during the DET determination step of an IR, 2R, ..., nR implementation of the POS step set, and if the supply voltage approaches a reference supply signal, or the phase shift Phi is substantially equal to zero (i.e., it tends towards zero, without actually being equal to zero).

[0132] - it remains constant when at least one malfunction D1, D2 is detected during the DET determination step of an implementation of the POS set of steps, and if the double condition is not met.

[0133] Advantageously, the confidence index cfi responds positively to a problem of possible non-determination of a malfunction Dl, D2 occurring at the very moment of the start of the centrifugal pump 2 (in other words, during a commissioning of the centrifugal pump 2 in a fault situation), due to the nature of said malfunction Dl, D2, since for each of the three sampled signals El, the maxima of amplitude Maxl 1, Maxl2 and the minima of amplitude min 1, minl2 of the tolerance ranges Pli, P12, of the fundamental line ROI, R02, of at least one subharmonic, and of at least one harmonic H11, H21, H31, H41, are initialized to zero at the start of the centrifugal pump 2.

[0134] The confidence index cfi also prevents the occurrence and persistence of a worst-case application situation in which: the malfunction Dl, D2 during the commissioning of the centrifugal pump 2 is not determined, and the centrifugal pump 2 operates in the stable OK2 operating regime. Indeed, in such an application situation, the supervisory process 100, during the update step MAJ of an IR implementation of the POS step assembly, which temporally follows the start-up step STA, would update the amplitude maxima Maxl 1, Maxl2 and the amplitude minima minl 1, minl2 of the different tolerance ranges Pli, P12 with erroneous values, which would then be used as a starting reference for the following implementations (j+l)R of the set of POS steps (more specifically, the CHE verification and DET determination steps), resulting in errors in the supervision of the centrifugal pump 2.

[0135] The value of the confidence index cfi evolves during the SP supervision phase as the CHE verification step and the DET determination step are implemented, as indicated above. A high confidence index cfi means that during the SP supervision phase of the centrifugal pump 2, few or no malfunctions D1, D2 occurred, with the centrifugal pump operating under nominal conditions; the amplitudes of the fundamental line IR01, PhiR02 of the fundamental line ROI, R02, of at least one subharmonic SH11, SH21, and of at least one harmonic H11, H21, H31, H41 being within their respective amplitude tolerance range Pli, P12.

[0136] Conversely, a low confidence index cfi can result in the occurrence of several malfunctions D1, D2, whether the centrifugal pump 2 is operating in a stable OK2 or unstable NOK2 operating regime. The confidence index cfi is notably decremented when a malfunction D1, D2 is detected during the determination phase, while the centrifugal pump 2 is operating in a stable OK2 operating regime, and: the supply voltage approaches a reference supply signal, or the phase shift Phi tends towards zero.

[0137] In one embodiment of the invention, the reference supply signal is a sinusoid with a frequency equal to the supply network frequency (50 Hz or 60 Hz) and an amplitude equal to the reference AC voltage (i.e., 230 VAC for centrifugal pumps 2 operating in single phase, or equal to 400 VAC for centrifugal pumps 2 operating in three phase).

[0138] In the case where the confidence index cfi becomes negative, the maxima of amplitude Maxl 1, Maxl2 and the minima of amplitude min 1, minl2 of the different amplitude tolerance ranges Pli, P12 are reset because it is then certain that they are erroneous.

[0139] As stated above, certain malfunctions D1, D2 are determined / detected by the supervisory process 100 from at least one analysis by the supervisory process 100 of the amplitudes IR01, PhiR02 of the fundamental line ROI, R02, of at least one subharmonic SH11, SH21, and of at least one harmonic H11, H21, H31, H41 composing each sampled signal EL. More precisely, these malfunctions D1, D2 are determined when, for at least one of the three sampled signals, at least:

[0140] - the amplitude IR01, PhiR02 of the fundamental line ROI, R02 is not included in the first amplitude tolerance range PI 1, P12, or

[0141] - the amplitude of at least one subharmonic SH11, SH21 is not included in at least one second amplitude tolerance range, or

[0142] - the amplitude of at least one harmonic H11, H21, H31, H41 is not included in at least a third amplitude tolerance range.

[0143] According to this principle, with reference to [Fig. 6], the monitoring method 100 is capable of detecting a malfunction D1, D2 and identifying it as an overload event D1 when, for the sampled signal El associated with the electric current intensity I, the amplitude IR01 of the fundamental line ROI becomes greater than kl times the first amplitude maximum Maxl 1, kl being a coefficient strictly greater than 1. In one embodiment of the invention, this coefficient kl is between 1.2 and 1.5. Temporally, this means that the electric current intensity I is no longer within a nominal operating current range, having exceeded a current threshold SI whose value is equal to kl times the first amplitude maximum Maxl 1 relative to the fundamental line ROI of the sampled signal El of the electric current intensity I.

[0144] Also, with reference to Figures 7 and 8, the monitoring method 100 is capable of detecting a malfunction D1, D2 and identifying it as a priming loss phenomenon D2 resulting in dry running of the centrifugal pump 2 when:

[0145] - for the sampled signal El associated with the electric current intensity I, the amplitude IR01 of the fundamental ROI line becomes less than k2 times the first amplitude minimum of the first amplitude tolerance range, k2 being a coefficient strictly less than 1 (with k2 between 0.70 and 0.98 in one embodiment of the invention); and

[0146] - for the sampled signal associated with the phase shift Phi, the amplitude PhiR02 of the line fundamental R02 becomes greater than the first maximum amplitude Max 12.

[0147] Temporally, this means that: - the electric current intensity I is no longer within the nominal operating current range, having fallen below an intensity threshold S2 whose value is equal to k2 times the first minimum amplitude mini 1 relative to the fundamental line ROI of the sampled signal El of the electric current intensity I; and

[0148] - the phase shift Phi is no longer within a functional phase shift range nominal operation having exceeded an intensity threshold S2' whose value is equal to the first minimum amplitude min 12 relative to the fundamental line R02 of the sampled signal of the phase shift Phi.

[0149] Also, during the DET determination step, the supervisory method 100 is capable of determining a malfunction at least as a function of a number of harmonics H11, H21, H31, H41 contained in each of the three exchanged signals. tilloned El.

[0150] Furthermore, the monitoring method 100 can determine a malfunction corresponding to abnormal vibration of the centrifugal pump 2 when, for at least one of the three sampled signals E1, the number of harmonics H11, H21, H31, H41 that it comprises during at least one second implementation (j+1)R of the POS step set becomes greater than the number of harmonics H11, H21, H31, H41 that it contained during at least one first implementation jR of the POS step set that temporally precedes said second implementation jR. This type of malfunction can be caused, but not limited to, defective bearings, the presence of air bubbles in the pumped fluid (which can cause cavitation), etc.

[0151] It is also capable of determining a malfunction corresponding to a disturbance in the power supply signal caused by interference with at least one piece of equipment external to the power source and connected to the same electrical network. This disturbance is detected when, for the sampled signal associated with the supply voltage:

[0152] - the number of harmonics H11, H21, H31, H41 that it comprises during at least one second implementation (j+l)R of the POS step set becomes greater than the number of harmonics H11, H21, H31, H41 it contained during at least one first implementation jR of the POS step set temporally preceding said at least one second implementation (j+l)R, with at least one additional harmonic counted in addition to the at least one harmonic H11, H21, H31, H41; and - that an amplitude of at least one additional harmonic is at least greater than k3 times the reference alternating voltage, k3 being a coefficient strictly greater than 1 (in one embodiment of the invention, k3 is between 1.1 and 1.5).

[0153] The monitoring method 100 can also determine that a malfunction Dl, D2 of the centrifugal pump 2 corresponds to a reversal of the direction of rotation of the centrifugal pump when a difference / a phase shift between the phase shifts measured during the measurement step MS, during two successive implementations jR, (j+l)R of the set of steps POS (j belonging to [1 ; n-1]), becomes equal to or greater than a critical phase shift value; which critical value can be between 30° and 120° in an embodiment of the invention.

[0154] The monitoring method 100 is also capable of detecting, during the DET determination step, other malfunctions which are not covered by the invention: - an under-powering of the centrifugal pump 2 detected when the voltage the power supply measured during the MS measurement step is less than the reference AC voltage (230 VAC for centrifugal pumps 2 operating in single phase, or equal to 400 VAC for centrifugal pumps 2 operating in three phase); - a power supply to the centrifugal pump which is cut off, and detected if the electric current intensity I measured during the MS measurement step is zero; - an absence of phase of the asynchronous motor of the centrifugal pump 2 when, for the sampled signal El associated with the electric current intensity I, the amplitude IR01 of the fundamental line ROI and the amplitude of at least one subharmonic SH11, SH21 are both equal to zero.

[0155] In the context of the implementation of the NSS signal sampling step, the frequency spectrum is between 500 Hz and 1 MHz.

[0156] In the described embodiment, the frequency spectrum is between 0.1 Hz and 250 Hz, in relation to the sampling frequency which is equal to 1 kHz.

[0157] In another embodiment of the invention, it is conceivable that the frequency spectrum is extended between 0.1 Hz and 100 KHz, so that harmonics H11, H21, H31, H41 located at high harmonic frequencies FH11, FH21, FH31, FH41 can be included in the sampled signals El, and possibly be detected during the DET determination step of malfunctions D1, D2 due to vibratory phenomena occurring for these said harmonic frequencies.

[0158] In the event that at least one malfunction D1, D2 is determined / detected during the DET determination step, the latter is followed by a WRN categorization step during which the at least one malfunction D1, D2 is categorized as:

[0159] - a minor fault dmi, with the centrifugal pump 2 controlled to continue to to function following the aforementioned WRN categorization step; - a major fault dMA, in which case the WRN categorization step is followed by a temporary stop step STP during which the centrifugal pump 2 is commanded to be temporarily stopped for a temporary stop time following the WRN categorization step, and then restarted once the temporary stop time has elapsed. In other words, during the WRN temporary stop step, the control unit 4 is configured to send a temporary stop signal to the centrifugal pump 2 to temporarily stop it, and then send it a restart signal to restart it once the temporary stop time has elapsed. Temporally, this WRN temporary stop step is implemented during the SP supervision phase, between two successive implementations jR, (j+l)R of the POS sequence of steps. - a critical fault dCr, in which case the WRN categorization step is followed by the OVR shutdown step to stop the centrifugal pump 2. In other words, following this ca In the tegorisation, the control unit 4 is configured to send a stop signal to the centrifugal pump 2.

[0160] When a malfunction D1, D2 is identified by the monitoring process 100 and categorized during an implementation jR of the POS step set as a minor fault dmi (respectively a major fault dMA), it can be classified as a major fault dMA (respectively a critical fault dCr) if it is identified during subsequent implementations (j+1)R, ..., nR of the POS step set. This overclassification depends on the number of times the malfunction is identified, regardless of whether it was identified during implementations IR, 2R, ... nR of the POS step set that are temporally sequential or not. This number of detections triggering the overclassification of a minor fault dmi or a major fault dMA is chosen by the designer of the monitoring process 100.

Claims

Demands

1. A monitoring method (100) for monitoring a centrifugal pump (2) driven by an asynchronous motor (21) and operating at a mains power frequency; the monitoring method comprising a start-up step (STA) during which the centrifugal pump (2) is started, this start-up step (STA) being followed by a monitoring phase (SP) comprising an iteration of a set of steps (POS), said set of steps (POS) comprising at least: - a measurement step (MS) during which three analog electrical quantities (I; Phi) are measured which correspond to: a supply voltage of the centrifugal pump (2) which can reach a reference alternating voltage, an electric current intensity (I) in the centrifugal pump (2), and a phase shift (Phi) between the supply voltage and the electric current intensity (I); - a signal sampling step (NSS) during which a mathematical function is applied to sample each of the three analog electrical quantities (I; Phi) at a sampling frequency, and at the end of which three sampled signals (El) are obtained respectively associated with the three analog electrical quantities (I; Phi), in which each of the three sampled signals (El) is represented in a frequency spectrum and includes a fundamental line (ROI; R02) at a fundamental frequency (FOI; F02) equal to the power supply network frequency, at least one subharmonic (SH11, SH21), and at least one harmonic (H11, H21, H31, H41); - a comparison step (CMP) during which, for each of the three sampled signals (El), an amplitude of at least one subharmonic (SH11, SH21) is compared to a stability threshold, such that the centrifugal pump (2) is determined to be operating in an unstable operating regime (NOK2) if the amplitude of at least one subharmonic (SH11, SH21) of at least one of the three sampled signals (El) is greater than or equal to the stability threshold associated with it, and determined to be operating in a stable operating regime (OK2) if the amplitude of at least one subharmonic (SH11, SH21) of the three sampled signals (El) is less than its respective stability threshold.

2. A monitoring method (100) according to claim 1, wherein the set of steps (POS) also includes a verification step (CHE) implemented following the comparison step (CMP), and during which it is verified, for each of the three sampled signals (El), whether: - an amplitude (IR01 ; PhiR02) of the fundamental line (ROI ; R02) is included in a first amplitude tolerance range (Pli ; P12) bounded by a first maximum amplitude (Maxl 1 ; Max 12) excluded and a first minimum amplitude (min 1 ; min 12) excluded; - the amplitude of at least one subharmonic (SH11, SH21) is included in at least a second amplitude tolerance range bounded by a second excluded amplitude maximum and a second excluded amplitude minimum; - an amplitude of at least one harmonic (H11, H21, H31, H41) is included in at least a third amplitude tolerance range bounded by a third excluded amplitude maximum and a third excluded amplitude minimum; and in which said verification step (CHE) is followed by a determination step (DET) during which it is determined whether the centrifugal pump (2) has at least one malfunction (DI; D2) based at least on the results of the verification step (CHE).

3. A monitoring method (100) according to claim 2, wherein, for each of the three sampled signals (El), at the start of the centrifugal pump (2), during the start-up step (STA), the first maximum amplitude (Maxl 1; Max 12), the first minimum amplitude (minll; minl2), the second maximum amplitude, the second minimum amplitude, the third maximum amplitude, and the third minimum amplitude are initialized to zero values; and in which the set of steps (POS) also includes an update step (MAJ) provided that the centrifugal pump (2) is operating in the stable operating regime (OK2), and following the determination step (DET) when no malfunction (DI; D2) of the centrifugal pump (2) has been detected; and during which, for each of the three sampled signals (El): - the first maximum amplitude (Maxl 1 ; Max 12) and the first minimum amplitude (minll ; min 12) become respectively equal to a minimum amplitude and a maximum amplitude of the amplitude (IR01 ; PhiR02) of the fundamental line (ROI ; R02); - the second maximum amplitude and the second minimum amplitude become respectively equal to a minimum amplitude and a maximum amplitude of the amplitude of at least one subharmonic (SH11, SH21); - the third maximum amplitude and the third minimum amplitude become respectively equal to a minimum amplitude and a maximum amplitude of the amplitude of at least one harmonic (H11, H21, H31, H41).

4. A monitoring method (100) according to claim 2 or 3, wherein a confidence index (cfi) is defined which: - is initialized to zero at the start-up of the centrifugal pump (2) during the start-up step (STA); - is incremented following the verification step (CHE) when it is verified that the amplitudes (IR01; PhiR02) of the fundamental line (ROI; R02), of at least one subharmonic (SH11, SH21), and of at least one harmonic (H11, H21, H31, H41) for each of the three sampled signals (E1) are respectively within the first amplitude tolerance range (P11; P12), within at least one second amplitude tolerance range, and within at least one third amplitude tolerance range; - remains constant when at least one malfunction (DI; D2) is detected during the determination step (DET); - is decremented when at least one malfunction (DI;D2) is detected during the determination step (DET), and if: the supply voltage approaches a reference supply signal, or the phase shift is substantially equal to zero.

5. A monitoring method (100) according to claim 4, wherein, following the determination step (DET), and in the case where the confidence index (cfi) becomes negative, the first maximum amplitude (Maxl 1; Maxl2), the first minimum amplitude (minll; minl2), the second maximum amplitude, the second minimum amplitude, the third maximum amplitude and the third minimum amplitude are reset to zero values ​​for each of the three sampled signals (El).

6. A monitoring method (100) according to claim 4 or 5, wherein the reference supply signal is a sinusoid of frequency equal to the supply network frequency and having an amplitude equal to the reference AC voltage.

7. A monitoring method (100) according to any one of claims 2 to 6, wherein, during the determination step (DET), at least one malfunction (DI; D2) is determined when, for at least one of the three sampled signals (El), at least: - the amplitude (IR01; PhiR02) of the fundamental line (ROI; R02) is not included in the first amplitude tolerance range (Pli, P12), or - the amplitude of at least one subharmonic (SH11, SH21) is not included in at least a second amplitude tolerance range, or - the amplitude of at least one harmonic (Hll, H21, H31, H41) is not included in at least a third amplitude tolerance range.

8. A monitoring method (100) according to claim 7, wherein at least one malfunction (DI; D2) is determined to be an overload (D1), and is detected when, for the sampled signal (El) associated with the electric current intensity (I), the amplitude (IR01) of the fundamental line (ROI) becomes greater than k1 times the first amplitude maximum (Max 11), k1 being a coefficient greater than strictly 1.

9. Supervisory method (100) according to claim 8, wherein the coefficient kl is between 1.2 and 1.

5.

10. A monitoring method (100) according to any one of claims 7 to 9, wherein at least one malfunction (D1; D2) is determined to be a priming phenomenon (D2) resulting in dry running of the centrifugal pump (2) when: - for the sampled signal (El) associated with the electric current intensity (I), the amplitude (IR01) of the fundamental line (ROI) becomes less than k2 times the first amplitude minimum (min 1) of the first amplitude tolerance range (Pli), k2 being a coefficient strictly less than 1; and - for the sampled signal associated with the phase shift (Phi), the amplitude (PhiR02) of the fundamental line (R02) becomes greater than the first amplitude maximum (Max 12).

11. Supervisory method (100) according to claim 10, wherein the coefficient k2 is between 0.70 and 0.

98.

12. A supervisory method (100) according to any one of claims 2 to 11, wherein, during the determination step (DET), the at least a malfunction (DI; D2) is determined at least as a function of a number of harmonics contained in each of the three sampled signals (El).

13. A monitoring method (100) according to claim 12 wherein at least one malfunction (DI; D2) is determined to be an abnormal vibration of the centrifugal pump (2) when, for at least one of the three sampled signals (El), the number of harmonics it comprises during at least one second implementation ((j+l)R) of the step set (POS) becomes greater than the number of harmonics it contained during at least one first implementation (jR) of the step set (POS) which temporally precedes said at least one second implementation ((j+l)R).

14. A monitoring method (100) according to claim 12 or 13, wherein at least one malfunction (DI; D2) is determined to be a disturbance of the supply signal when, for the sampled signal associated with the supply voltage: - the number of harmonics it comprises during at least one second implementation ((j+l)R) of the step set (POS) becomes greater than the number of harmonics it contained during at least one first implementation (jR) of the step set (POS) temporally preceding said at least one second implementation ((j+l)R), with at least one additional harmonic counted in addition to the at least one harmonic (SH11, SH21); and - that an amplitude of the at least one additional harmonic is at least greater than k3 times the reference AC voltage, k3 being a coefficient strictly greater than 1.

15. Supervisory method (100) according to claim 14, wherein the coefficient k3 is between 1.1 and 1.

5.

16. A monitoring method (100) according to any one of claims 2 to 15, wherein, during the determination step (DET), at least one malfunction (DI; D2) is determined to be a reversal of the direction of rotation of the centrifugal pump (2) when a phase shift difference between the phase shifts (Phi) measured during the measurement step (MS), during two successive implementations (jR, (j+l)R) of the set of steps (POS), becomes equal to or greater than a critical phase shift value.

17. A monitoring method (100) according to claim 16, wherein the critical phase shift value is between 30° and 120°.

18. A monitoring method (100) according to any one of claims 2 to 17, wherein the set of steps (POS) includes a categorization step (WRN) which is implemented after the determination step (DET) if, during the latter, it is determined that the centrifugal pump (2) has at least one malfunction (DI; D2), and during which said at least one malfunction (DI; D2) is categorized as: - a minor fault (dmi), with the centrifugal pump (2) controlled to continue operating following said categorization step; - a major fault (dMA), with the centrifugal pump (2) controlled to be temporarily stopped for a temporary stop time following the categorization step (WRN), and then restarted once the temporary stop time has elapsed; - a critical fault (dCr), with the centrifugal pump (2) commanded for shutdown following the categorization step (WRN).

19. A monitoring method (100) according to claim 18, wherein at least one malfunction (DI; D2), if categorized as a minor fault (dmi), respectively a major fault (dMA), during at least one first implementation (jR) of the set of steps (POS), is categorized as a major fault (dMA), respectively a critical fault (dCr), during at least one second implementation ((j+1)R) of the set of steps (POS) occurring temporally after at least one first implementation (jR).

20. A monitoring method (100) according to any one of the preceding claims, wherein, for each of the three sampled signals (El), the stability threshold associated with at least one subharmonic (SH11, SH21) is equal to the amplitude (IR01; PhiR02) of the fundamental line (ROI; R02) multiplied by a coefficient k4 representative of a frequency of at least one subharmonic (SH11, SH21).

21. Supervisory method (100) according to claim 20, wherein the coefficient k4 is between 0.01 and 0.

5.

22. A monitoring method (100) according to any one of the preceding claims, wherein, for each of the three sampled signals (E1), at least one subharmonic (SH11, SH21) comprises: - a first subharmonic (SH11) at a first subharmonic frequency (FSH11) which is, for example, equal to the fundamental frequency (F01; F02) divided by two; - a second subharmonic at a second subharmonic frequency harmonic which is for example equal to the fundamental frequency (FOI; F02) divided by four; and - a third subharmonic at a third subharmonic frequency which is for example equal to the fundamental frequency (FOI; F02) divided by eight.

23. A monitoring method (100) according to any one of the preceding claims, wherein, for each of the three sampled signals (E1), at least one harmonic (H11, H21, H31, H41) comprises: - a first harmonic (H11) at a first harmonic frequency (FH11) which is, for example, equal to the fundamental frequency (FOI; F02) multiplied by two; - a second harmonic (H31) at a second harmonic frequency (FH31) which is, for example, equal to the fundamental frequency (FOI; F02) multiplied by four; and - a third harmonic (H41) at a third harmonic frequency (FH41) which is, for example, equal to the fundamental frequency (FOI; F02) multiplied by eight.

24. A monitoring method (100) according to any one of the preceding claims, wherein the sampling frequency is between 500Hz and 1MHz.

25. A monitoring method (100) according to any one of the preceding claims, wherein the frequency spectrum is between 0.1 Hz and 100 kHz.

26. A monitoring method according to claim 24, wherein the sampling frequency is equal to 1kHz.

27. ​​A monitoring method (100) according to claims 25 and 26, wherein the frequency spectrum is between 0.1 Hz and 250 Hz.

28. A monitoring method (100) according to any one of the preceding claims, wherein the reference AC voltage is equal to 230 VAC, or 400 VAC.

29. Supervisory system (1) for supervising a centrifugal pump (2) driven by an asynchronous motor (21) and operating at a mains supply frequency, said supervisory system (1) being at least in communication with the centrifugal pump (2), and comprising: - at least one measuring system (3) configured to measure at least one of three analog electrical quantities (I, Phi) which correspond to: a supply voltage of the centrifugal pump (2) capable of reaching a reference alternating voltage, an electric current intensity (I) in the centrifugal pump (2), and a phase shift (Phi) between the supply voltage and the electric current intensity (I); and - at least one control unit (4) in communication with the measurement system (3); said control unit (4) comprising a memory, and a processor which is configured to execute a program for an implementation of the supervisory method according to any one of claims 1 to 28.

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