Supervision method for automated and autonomous supervision of centrifugal pumps with asynchronous motors

Abstract

The invention relates to a supervision method for supervising a centrifugal pump (2), which notably comprises a supervision phase during which the centrifugal pump is determined as operating in a stable operating regime or an unstable operating regime. This determination is based on an analysis of amplitudes of sub-harmonics included in different sampled signals, which sampled signals are obtained following the sampling of measured analog electrical quantities relating to the operation of the centrifugal pump. Abstract figure: Figure 1

Description

Title of the invention: Supervision method for automated and autonomous supervision of centrifugal pumps with asynchronous motors Technical field

[0001] The invention relates to a supervision method.

[0002] It relates more particularly to a supervision method capable of automatically and autonomously supervising centrifugal pumps with asynchronous motors, in particular by being capable of controlling their stability and identifying whether they exhibit anomalies during their operation.

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

[0004] The invention finds a preferred, and non-limiting, application in the field of pumping stations using centrifugal pumps with asynchronous motors, for example: for the supply, filtration, lifting, drilling, collection, transfer, circulation of water. Prior art

[0005] In a known manner, to determine whether a centrifugal pump with an asynchronous motor is operating correctly or not, its flow rate / pressure curve is analyzed. By flow rate / pressure curve, we mean a change in the discharge pressure of the centrifugal pump as a function of its discharge flow rate. To determine whether a centrifugal pump is operating correctly, it is useful to determine whether the operating point is at the center or at the ends of the flow rate / pressure curve. In particular, operation at zero flow rate or zero pressure can be destructive.

[0006] A centrifugal pump may exhibit a plurality of malfunctions such as: a malfunction due to an electrical overload, or to a power supply that is too low or disturbed; a reverse rotation of the centrifugal pump due to an inversion of the order of the phases of a three-phase power 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 priming resulting in dry running of the pump; etc.

[0007] There are numerous protection devices for protecting centrifugal pumps with asynchronous motors, for example and not exhaustively: motor circuit breakers which protect against overcurrents and overloads; dry running protection devices which detect undercurrent or phase shift in the face of flow / pressure anomalies linked to such dry running; protective positives to detect and signal cases of rotation reversal, bearing wear; etc.

[0008] As a motor converts electrical energy into mechanical energy, there is a correspondence between its electrical behavior and its mechanical behavior. By extrapolation, it is possible to identify abnormal operation of a pump by analyzing its electrical consumption. Mechanical instability of the pump results in electrical instability. The variations in electrical quantities are therefore like the mechanical variations of the asynchronous motor.

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

[0010] These protection devices, however, have several drawbacks. First of all, they require a user to manually adjust all the trigger thresholds, depending on the pump model. This manual adjustment therefore requires the user to know precisely the values ​​of these operating thresholds, i.e., to have complete control over the operation of the centrifugal pump 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 expertise from the operator, and is also very time-consuming (which impacts the time required to commission the centrifugal pump). In the case where the trigger thresholds are not adjusted or are incorrectly adjusted, the pump will be poorly protected.

[0011] As the functional characteristics of a centrifugal pump may vary depending on the pump reference and its installation environment, this means that the trigger thresholds may not be the same. Thus, an operator would have to carry out a step of setting the trigger thresholds again if he had to use the same protection device for centrifugal pumps of different references 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 supervision method capable of autonomously (i.e. without human intervention) and automated supervision of a centrifugal pump with an asynchronous motor. The supervision 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 the event of a 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 supervision method for supervising a centrifugal pump driven by an asynchronous motor and operating at a power supply network frequency; the supervision method comprising a start-up step during which the centrifugal pump is started, this start-up step being followed by a supervision 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 electrical current intensity in the centrifugal pump, and a phase shift between the supply voltage and the electrical current intensity; - a signal sampling step during which a mathematical function is applied to sample each of the three analog electrical quantities at 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 comprises a fundamental line at a fundamental frequency equal to the power supply network frequency, at least one sub-harmonic, and at least one harmonic; - a comparison step during which, for each of the three sampled signals, an amplitude of the at least one sub-harmonic is compared to a stability threshold, such that the centrifugal pump is determined as operating in an unstable operating regime if the amplitude of the at least one sub-harmonic of at least one of the three sampled signals is greater than or equal to the stability threshold associated with it, and determined as operating in a stable operating regime if the amplitude of the at least one sub-harmonic 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 supervision phase of the supervision method advantageously makes it possible to determine at any time the operating regime of a centrifugal pump, i.e. whether it is operating in a stable operating mode or in an unstable operating mode. The monitoring process actually makes it possible to detect when a centrifugal pump may switch from a stable operating mode to an unstable operating mode.

[0016] As specified above, the operating regime of a centrifugal pump is determined by analysis of sampled signals relating to three analog physical quantities on which the active power of the centrifugal pump depends (i.e. the electrical power that it absorbs), and which correspond to: - the supply voltage of the centrifugal pump, which can reach a reference alternating voltage which corresponds to a maximum supply voltage capable of being supplied by a power source (for example, the electrical network, a generator set) of the centrifugal pump; - the intensity of 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 by means of 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 on a frequency spectrum by means of a mathematical function designed to sample the analog signals (for example, the Fast Fourier Transform, FFT in English) at a sampling frequency: which is synchronized to a power supply network frequency (which power supply network frequency may be equal to 50 Hz or 60 Hz); and which complies with the Shannon criterion. The sampled signal relating to each analog physical quantity comprises a fundamental line at a fundamental frequency equal to the power supply network, at least one harmonic at a frequency equal to a multiple of the fundamental frequency, and at least one sub-harmonic at a frequency equal to a sub-multiple of the fundamental frequency.

[0019] During the comparison step, the amplitude of the at least one sub-harmonic of each sampled signal is compared to a stability threshold which is specific to said 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 the at least one sub-harmonic of a sampled signal comprises several sub-harmonics, then the amplitudes of the several sub-harmonics 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 if it is verified that, for each of the three sampled signals, its at least one subharmonic is less than the stability threshold. Otherwise, if the 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 operates in an unstable operating regime.

[0021] According to one embodiment of the invention, the supervision phase comprises an acquisition step with the aim of acquiring / memorizing the sampled signals associated with the three physical quantities.

[0022] According to a characteristic of the invention, the set of steps also comprises 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 amplitude maximum and a first excluded amplitude minimum; and

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

[0025] - an amplitude of the at least one harmonic is included in 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 step of determining the supervision phase, the supervision method is capable of determining whether at least one malfunction occurs during the operation of a centrifugal pump. Optionally, the at least one malfunction may cause the centrifugal pump to switch from the stable operating regime to the unstable operating regime.

[0028] Furthermore, the at least one malfunction can be determined by the supervision 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 the at least one harmonic, and of the at least one sub-harmonic are or are not included in amplitude tolerance ranges.

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

[0030] In other words, the amplitude maxima and amplitude minima defining the amplitude tolerance ranges associated with the fundamental line, the at least one harmonic, and the 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 first initialized to zero when the centrifugal pump is started.They are then, during the supervision phase, updated automatically by the supervision method when, at a time t, it is detected that the centrifugal pump is operating in a stable operating regime and that it does not exhibit any malfunction, so that, for the three sampled signals, the amplitude maxima and minima of the amplitude tolerance ranges associated respectively with the fundamental line, with the at least one harmonic, and with the at least one sub-harmonic, correspond to the maximum and minimum of the amplitude of the fundamental line, of the at least one harmonic, and of the at least one sub-harmonic at said time t.

[0031] The values ​​of the amplitude maxima and amplitude minima of the amplitude tolerance ranges depend on the functional characteristics of a centrifugal pump. Since they are not predefined in the supervision method, the latter is advantageously, as indicated above, applicable to all types of centrifugal pump reference.

[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 supervision process by an operator of the centrifugal pump; meaning that said operator also does not need to have knowledge of these said amplitude maxima and amplitude minima.

[0033] According to a characteristic 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 the at least one sub-harmonic, and of the at least one harmonic for each of the three sampled signals are respectively included in the first amplitude tolerance range, in the at least one second amplitude tolerance range, and in the 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 characteristic of the invention, following the determination step, and in the case where the confidence index becomes negative, the first amplitude maximum, the first amplitude minimum, the second amplitude maximum, the second amplitude minimum, the third amplitude maximum and the third amplitude minimum 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 starting the centrifugal pump (in other words, during commissioning of the centrifugal pump in a fault situation), due to the nature of said malfunction, since for each of the three sampled signals E1, the minima and maxima of amplitude of the tolerance ranges of the fundamental line, of the at least one sub-harmonic, and of the at least one harmonic, are initialized to zero at the start of the centrifugal pump.

[0036] The confidence index also makes it possible to avoid the occurrence and persistence of a worst-case application situation for which: the malfunction during commissioning of the centrifugal pump is not determined, and the centrifugal pump operates in the stable operating regime. Indeed, in such an application situation, the supervision method, of the step of updating an implementation of the set of steps temporally directly following the start-up step, would update the amplitude maxima and the amplitude minima of the different tolerance ranges with erroneous values, which would then be used as a starting reference for the following implementations of the set of steps (more precisely, the verification and determination steps), with the consequence of errors in the centrifugal pump supervision.

[0037] The value of the confidence index evolves during the supervision phase as the verification step and the determination step are implemented as indicated above. A high confidence index means that during the supervision phase of the centrifugal pump, few or no malfunctions occurred, with the centrifugal pump operating in a nominal situation; the amplitudes of the fundamental line, of the at least one sub-harmonic, and of the at least one harmonic being included in their respective amplitude tolerance range.

[0038] Conversely, a low confidence index may result in the occurrence of several malfunctions, whether the centrifugal pump is operating in a stable or unstable operating regime. The confidence index is notably decremented when a malfunction is detected during the determination phase, while the centrifugal pump is operating in a stable operating regime and the supply voltage is approaching a reference supply signal, or the phase shift is tending to become zero (i.e. it is becoming close to zero, without being equal to 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 power supply signal is a sinusoid of frequency equal to the power supply network frequency and having an amplitude equal to the reference alternating voltage.

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

[0042] In other words, and as mentioned previously, during the determination step, from the results of the verification step, the supervision method is advantageously capable of detecting malfunctions and determining their nature. Malfunctions are in particular detected and identified depending on whether the amplitudes of the fundamental line, of the at least one sub-harmonic, and of the at least one harmonic, for each of the three sampled signals, are included or not in their respective amplitude tolerance range.

[0043] According to a characteristic of the invention, the at least one malfunction is determined as being 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 supervision method is capable, if it determines that the centrifugal pump has a malfunction, of identifying the latter as being an overcurrent / overload phenomenon, which is characterized by an excess 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 relating to said fundamental line.

[0046] According to a characteristic of the invention, the at least one malfunction is determined as being a loss of priming phenomenon resulting in dry running of the centrifugal pump 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 supervision method is capable of detecting, during operation of a centrifugal pump, loss of priming phenomena, which result: temporally, by a drop in the electric current intensity below a nominal value and an increase in the phase shift value, and frequently, as described above.

[0049] According to a characteristic of the invention, during the determination step, the 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 characteristic of the invention, the at least one malfunction is determined as being an abnormal vibration of the centrifugal pump when, for at least one of the three sampled signals, a number of harmonics that it comprises during at least one second implementation of the set of steps becomes greater than the number of harmonics that it contained during at least one first implementation of the set of steps which temporally precedes said at least one second implementation.

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

[0052] The supervision method is in particular capable of detecting abnormal vibrations of the centrifugal pump which may, but not limited to, be caused by defective bearings, the presence of air bubbles in the pumped fluid (which may cause cavitation), etc. These vibrations are detected by the supervision 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 characteristic of the invention, the at least one malfunction is determined as being a disturbance of the supply signal when, for the sampled signal associated with the supply voltage when: - the number of harmonics that it comprises during at least one second implementation of the set of steps becomes greater than the number of harmonics that 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 supervision method is also advantageously capable of detecting disturbances of the power supply signal, which may be of short duration or permanent, and which may be caused by interference with equipment external to the power supply source and which are connected to the same electrical network. These disturbances are detected by the supervision method when the number of harmonics of the sampled signal relative to the power supply voltage increases between two successive implementations of the set of steps, and the amplitude of the at least one new harmonic is k3 times the reference alternating voltage.

[0056] According to a characteristic of the invention, in which, during the determination step, the at least one malfunction is determined as being a reversal of the direction of rotation of the centrifugal pump when a difference in phase shift 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 may occur if the centrifugal pump is powered by a three-phase power source and the order of the phases of this power source is accidentally reversed.

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

[0060] According to a characteristic of the invention, the set of steps comprises 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 ordered to continue operating following said categorization step; - a major fault, with the centrifugal pump ordered to be temporarily stopped during a temporary downtime following the categorization step, then restarted once the temporary downtime has elapsed; - a critical fault, with the centrifugal pump ordered to shut down following the categorization step.

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

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

[0063] In other words, when a malfunction is identified by the supervision method during a determination step, and this is categorized as a minor or major defect, its severity level may change from minor to major, or from major to critical, if the same malfunction is identified several times during subsequent implementations of the set of steps (and therefore the determination step). This upgrade is a function of the number of times the malfunction is identified, regardless of whether it is detected for implementations that follow one another temporally or not. For example: - in a given application context, the malfunction can be identified for an implementation n of the set of steps, an implementation n+1, an 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 the at least one sub-harmonic is equal to the amplitude of the fundamental line multiplied by a coefficient k4 representative of a frequency of the at least one sub-harmonic.

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

[0066] According to a characteristic of the invention, for each of the three sampled signals, the at least one sub-harmonic 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 a characteristic of the invention, for each of the three sampled signals, the 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 supervision system for supervising a centrifugal pump driven by an asynchronous motor and operating at a power supply network frequency, which supervision system is at least in communication with the centrifugal pump, and comprising: - at least one measuring system designed to measure at least one of three analog electrical quantities which correspond to: a supply voltage of the centrifugal pump capable of reaching 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; and - a control unit at least in communication with the measurement system; said control unit comprising a memory, and a processor which is configured to execute a program for implementing the supervision method as previously described. Brief description of the drawings

[0074] Other characteristics and advantages of the present invention will appear on reading the detailed description below, of a non-limiting example of implementation, made with reference to the appended figures in which:

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

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

[0077] [Fig.3] is a flow diagram of the supervision process;

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

[0079] [Fig.5] is an illustration of an analog electrical quantity, which corresponds to an electric current intensity, relating to the operation of the centrifugal pump which is measured during a measurement step included in a supervision phase which includes the supervision method (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 supervision method when the fundamental line of the sampled signal relating to the electric current intensity becomes greater than kl times a first amplitude maximum limiting / delimiting a first amplitude tolerance range for this fundamental line (b);

[0081] [Fig.7] is an illustration of one of the two conditions for which a malfunction of the centrifugal pump corresponding to a loss of priming phenomenon is observed (a), this condition being detected by the supervision system when the fundamental line of the sampled signal relating to the electric current intensity becomes less than k2 times a first amplitude minimum limiting / 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 for which a malfunction of the centrifugal pump corresponding to a loss of priming phenomenon is observed (a), this condition being detected by the supervision 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 amplitude maximum limiting / 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, in an autonomous (i.e. without human intervention) and automated manner, the operation of a centrifugal pump 2 which is, for example, immersed for example 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 concerns 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 included in a stator 211. The asynchronous motor 21 is shaped 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 allowing 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 suitable for monitoring 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 a supervision system 1 at least in communication with the centrifugal pump 2. The supervision system comprises: - a measuring system 3 whose role 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 comprises a memory, as well as a processor configured to execute a program containing a list of instructions for implementing the supervision method 100.

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

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

[0092] The set of steps POS comprises a measurement step MS during which the measurement system 3 measures three analog electrical quantities I, Phi which correspond to: - a supply voltage for centrifugal pump 2 that can reach a reference alternating voltage. For centrifugal pumps operating in single-phase, the reference alternating voltage is equal to 230 VAC for centrifugal pumps 2 operating in single-phase. For centrifugal pumps operating in three-phase, the reference alternating voltage is either equal to 400 VAC if the electrical network supplying centrifugal pump 2 is three-phase 400 VAC (3*400 VAC), or equal to 230 VAC if the electrical network supplying 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 measurement step MS 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 configured to sample the analog signals (for example, the Fast Fourier Transform, FFT in English) at a sampling frequency: which is synchronized to the power supply network frequency at which the centrifugal pump 2 operates; and which complies with the Shannon criterion.

[0095] In the context of the invention, the sampling frequency may 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 network frequency is considered to be equal to 50 Hz (in another embodiment, the power supply network 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 comprises a fundamental line ROI, R02 at a fundamental frequency FOI, F02 corresponding to the power supply network frequency; at least one sub-harmonic SH11, SH21 whose frequency is a sub-multiple 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, the at least one sub-harmonic 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, the at least one harmonic H11, H21, H31, H34 can comprise:

[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 centrifugal pump 2 operating in single-phase, an example of 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 frequency FOI of 50 Hz, - two subharmonics SH11, SH21 respectively at the 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 Hll, H21, H31, H41 at harmonic frequencies FH11, FH21, FH31, FH41 equal to 100 Hz, 150 Hz, 200 Hz, and 400 Hz (otherwise at frequencies equal to F01*2, F01*3, F01*4, F01*8).

[0108] The amplitudes of the fundamental line FOI, of the sub-harmonics SH11, SH21 and of the harmonics Hll, 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 sub-harmonics SH11, SH21 or harmonics FH11, FH21, FH31, FH41 at particular frequencies. In particular, the following are distinguished: - the sub-harmonics and harmonics reflecting a nominal behavior of the centrifugal pump, such as the sub-harmonic SH21 located at the sub-harmonic frequency FSH21 equal to F01 / 3 and which is an indicator of a rotation speed of the rotor 2101, in particular in the case of centrifugal pumps 2 operating in single-phase; or the sub-harmonic SH11 located at the sub-harmonic frequency FSH11 equal to F01 / 2 which can be an indicator of mechanical / electrical stability or instability of the centrifugal pump 2; - harmonics H21, H31 due to distortions which may occur at the level of the transmission shaft 23 (due for example to wear of the bearings 230) or of the hydraulic part (due for example to an imbalance of a blade of the turbine 24; - sub-harmonics and harmonics resulting from electrical noise, such noise being able to be caused by random variations or fluctuations in the electrical 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 set of steps POS comprises, following the signal sampling step NSS, an acquisition step AQS is implemented 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. 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 sub-harmonic SH11, SH21; and of their at least one harmonic Hll, H21, H31, H41.

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

[0112] Following the signal sampling step NSS, a comparison step CMP is also implemented during which the amplitude of the at least one sub-harmonic SH11, SH21 of each sampled signal El is compared to a stability threshold which is 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 sub-harmonic SH11, SH21 of a sampled signal comprises several sub-harmonics (as in the case of the example given [Fig. 5]), then the amplitudes of the several sub-harmonics 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 operating regime OK2 if it is verified that, for each of the three sampled signals El, at least one subharmonic SH11, SH21 is less than the stability threshold. Otherwise, if the 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, then the centrifugal pump 2 is operating in an unstable operating regime NOK2.

[0113] In one embodiment of the invention, the stability threshold associated with the at least one sub-harmonic 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 sub-harmonic frequency FHSH11, FSH21 at which the at least one sub-harmonic SH11, SH21 is located.

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

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

[0116] Optionally, the at least one malfunction D1, D2 may 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 supervision method 100 of the amplitudes IR01, PhiR02 of the fundamental line ROI, R02, of Eau minus one sub-harmonic SH11, SH21, and of the at least one harmonic H11, H21, H31, H41 composing each sampled signal El.

[0118] Thus, following the comparison step CMP, and prior to the determination step DET, a verification step CHE 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 included in a first amplitude tolerance range PI 1, P12 bounded by a first amplitude maximum Maxl 1, Max 12 excluded and a first amplitude minimum mini 1, min 12 excluded; and

[0120] - the amplitude of the at least one subharmonic SH11, SH21 is included in at least 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 Hll, 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.

[0122] The first amplitude maximum Maxl 1, Max 12, the first amplitude minimum minll, minl2, the second amplitude maximum, the second amplitude minimum, the third amplitude maximum, and the third amplitude minimum are defined such that: - they are initialized to zero values ​​when the centrifugal pump is started, - during an implementation of the 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] Concerning the second point, the updates are carried out such that, during an implementation of the set of POS steps: - the first amplitude maximum Maxl 1, Max 12 and the first amplitude minimum mini 1, minl2 become respectively equal to a minimum amplitude and a maximum amplitude of the amplitude IR0, PhiR02 of the func- damentale ROI, R02; - the second amplitude maximum and the second amplitude minimum become respectively equal to an amplitude minimum and an amplitude maximum of the amplitude of the at least one subharmonic SH11, SH21;

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

[0125] In other words, the values ​​of the different amplitude maxima Maxl 1, Maxl2 and amplitude minima 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 following implementation of index (j+l)R of the set of POS steps.

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

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

[0128] The values ​​of the different amplitude maxima Maxl 1, Maxl2 and amplitude minima mini 1, min 12 depend on the functional characteristics of the centrifugal pump 2. Since they are not predefined in the supervision method 100, the latter is advantageously applicable to all types of centrifugal pump reference operating in single-phase or three-phase. Given that the amplitude maxima Maxl 1, Max 12 and the amplitude minima mini 1, min 12 of the amplitude tolerance ranges P1, P12 are determined automatically, they do not have to be provided to the supervision method 100 by an operator of the centrifugal pump 2; meaning that said operator does not need to have detailed knowledge of the operation of the centrifugal pump 2 and of these said amplitude maxima Maxl 1, Max 12 and minimum amplitude min 1, min 12.

[0129] The supervision method 100 comprises the definition of a confidence index cfi such that: - it is initialized to zero when 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 set of steps POS when it is verified that the amplitudes IR01, PhiR02 of the fundamental line ROI, R02, of the at least one sub-harmonic SH11, SH21, and of the at least one harmonic H11, H21, H31, H41 for each of the three sampled signals El are respectively included in the first amplitude tolerance range P11, P12, in the at least one second amplitude tolerance range, and in the 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 set of steps, 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 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 set of steps POS, 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 D1, D2 occurring at the very moment of starting the centrifugal pump 2 (in other words, during commissioning of the centrifugal pump 2 in a fault situation), due to the nature of said malfunction D1, D2, since for each of the three sampled signals El, the amplitude maxima Maxl 1, Maxl2 and the amplitude minima min 1, minl2 of the tolerance ranges P1, P12, of the fundamental line ROI, R02, of the at least one sub-harmonic, and of the 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 makes it possible to avoid the occurrence and persistence of a worst-case application situation for which: the malfunction D1, D2 during the commissioning of the centrifugal pump 2 is not determined, and the centrifugal pump 2 operates in the stable operating regime OK2. Indeed, in such an application situation, the supervision method 100, during the update step MAJ of an implementation IR of the set of steps POS temporally directly following the start-up step STA, would update the amplitude maxima Maxl 1, Maxl2 and the amplitude minima min 1, minl2 of the different tolerance ranges P1, 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 precisely, the CHE verification and DET determination steps), resulting in errors in the supervision of centrifugal pump 2.

[0135] The value of the confidence index cfi evolves during the supervision phase SP over the implementations of the verification step CHE and the determination step DET as indicated above. A high confidence index cfi means that during the supervision phase SP of the centrifugal pump 2, few or no malfunctions D1, D2 occurred, with the centrifugal pump operating in a nominal situation; the amplitudes of the fundamental line IR01, PhiR02 of the fundamental line ROI, R02, of the at least one sub-harmonic SH11, SH21, and of the at least one harmonic H11, H21, H31, H41 being included in their respective amplitude tolerance range P11, P12.

[0136] Conversely, a low confidence index cfi may result in the occurrence of several malfunctions D1, D2, whether the centrifugal pump 2 is operating in a stable operating regime OK2 or unstable NOK2. 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 operating regime OK2, and: the supply voltage is approaching a reference supply signal, or the phase shift Phi is tending towards zero.

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

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

[0139] As indicated above, certain malfunctions D1, D2 are determined / detected by the supervision method 100 from at least one analysis by the supervision method 100 of the amplitudes IR01, PhiR02 of the fundamental line ROI, R02, of at least one sub-harmonic SH11, SH21, and of the 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 the 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 one third amplitude tolerance range.

[0143] According to this principle, with reference to [Fig.6], the supervision 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 k1 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 intensity range by having exceeded an intensity threshold SI whose value is equal to k1 times the first amplitude maximum Maxl 1 relating 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 supervision method 100 is capable of detecting a malfunction D1, D2 and of identifying it as being a loss of priming 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 line ROI 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 Phi phase shift, 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 included in the nominal operating intensity range having passed below an intensity threshold S2 whose value is equal to k2 times the first minimum amplitude 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 included in a phase shift range of func nominal operation having exceeded an intensity threshold S2' whose value is equal to the first minimum of amplitude min 12 relating to the fundamental line R02 of the sampled signal of the phase shift Phi.

[0149] Also, during the DET determination step, the supervision 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 signals exchanged. hilled El.

[0150] Furthermore, the supervision method 100 can determine a malfunction corresponding to an abnormal vibration of the centrifugal pump 2 when, for at least one of the three sampled signals E1, a number of harmonics H11, H21, H31, H41 that it comprises during at least one second implementation (j+1)R of the set of steps POS becomes greater than the number of harmonics H11, H21, H31, H41 that it contained during at least one first implementation jR of the set of steps POS which temporally precedes said second implementation jR. This type of malfunction can be caused, without limitation, by 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 of the power supply signal caused by interference with at least one piece of equipment external to the power supply source and which is connected to the same electrical network. This disturbance is detected when, for the sampled signal associated with the power supply voltage:

[0152] - the number of harmonics H11, H21, H31, H41 that it includes during at least one second implementation (j+l)R of the set of POS steps becomes greater than the number of harmonics Hll, H21, H31, H41 that it contained during at least one first implementation jR of the set of POS steps 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 Hll, H21, H31, H41; 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 (in one embodiment of the invention, k3 is between 1.1 and 1.5).

[0153] The supervision method 100 can also determine that a malfunction D1, 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 deviation between the phase shifts measured during the measurement step MS, during two successive implementations jR, (j+1)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 comprised in an embodiment of the invention between 30° and 120°.

[0154] The supervision method 100 is also capable of detecting, during the DET determination step, other malfunctions which are not covered by the invention: - an undersupply of centrifugal pump 2 detected when the voltage power supply measured during the MS measurement step is lower than the reference alternating 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 measurement step MS is zero; - a phase absence 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 the at least one sub-harmonic 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 E1, and possibly be detected during the step DET of determining malfunctions D1, D2 due to vibration phenomena occurring for these said harmonic frequencies.

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

[0159] - a minor dmi fault, with centrifugal pump 2 commanded to continue to operate following said 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, 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, 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 supervision phase SP, between two successive implementations jR, (j+l)R of the set of steps POS. - a critical fault dCr, in which case the WRN categorization step is followed by the OVR shutdown step to stop centrifugal pump 2. In other words, following this ca tegorization, 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 supervision method 100 and is categorized during an implementation jR of the set of POS steps as a minor fault dmi (respectively a major fault dMA), it can be qualified as a major fault dMA (respectively a critical fault dCr) if it is identified during subsequent implementations (j+1)R, ..., nR of the set of POS steps. This upgrading is a function of the number of times the malfunction is identified, regardless of whether it was identified during implementations IR, 2R, ... nR of the set of POS steps temporally succeeding one another or not. This number of detections triggering the upgrading of a minor fault dmi or a major fault dMA is chosen by the designer of the supervision method 100.

Claims

Claims

1. Supervision method (100) for supervising a centrifugal pump (2) driven by an asynchronous motor (21) and operating at a power supply network frequency; the supervision method comprising a start-up step (STA) during which the centrifugal pump (2) is started, this start-up step (STA) being followed by a supervision 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 comprises a fundamental line (ROI; R02) at a fundamental frequency (FOI; F02) equal to the power supply network frequency, at least one sub-harmonic (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 the at least one sub-harmonic (SH11, SH21) is compared to a stability threshold, such that the centrifugal pump (2) is determined as operating in an unstable operating regime (NOK2) if the amplitude of the at least one sub-harmonic (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 as operating in a stable operating regime (OK2) if the amplitude of the at least one sub-harmonic (SH11, SH21) of the three sampled signals (El) is less than its respective stability threshold.

2. Supervision method (100) according to claim 1, in which the set of steps (POS) also comprises 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 amplitude maximum (Maxl 1; Max 12) excluded and a first amplitude minimum (mini 1; min 12) excluded; - the amplitude of the 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 (Hll, 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 wherein said verification step (CHE) is followed by a determination step (DET) during which it is determined whether or not the centrifugal pump (2) has at least one malfunction (DI; D2) based on at least the results of the verification step (CHE).

3. Supervision method (100) according to claim 2, in which, for each of the three sampled signals (El), at the start of the centrifugal pump (2), during the start 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 comprises an update step (MAJ) provided that the centrifugal pump (2) operates 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 amplitude maximum (Maxl 1; Max 12) and the first amplitude minimum (minll; min 12) become respectively equal to an amplitude minimum and an amplitude maximum of the amplitude (IR01; PhiR02) of the fundamental line (ROI; R02); - the second amplitude maximum and the second amplitude minimum become respectively equal to an amplitude minimum and an amplitude maximum of the amplitude of the at least one subharmonic (SH11, SH21); - the third amplitude maximum and the third amplitude minimum become respectively equal to an amplitude minimum and an amplitude maximum of the amplitude of the at least one harmonic (Hll, H21, H31, H41).

4. Supervision method (100) according to claim 2 or 3, in which a confidence index (cfi) is defined which: - is initialized to zero when the centrifugal pump (2) is started 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 the at least one sub-harmonic (SHll, SH21), and of the at least one harmonic (Hll, H21, H31, H41) for each of the three sampled signals (El) are respectively included in the first amplitude tolerance range (Pli; P12), in the at least one second amplitude tolerance range, and in the 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. Supervision 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 amplitude maximum (Maxl 1; Maxl2), the first amplitude minimum (minll; minl2), the second amplitude maximum, the second amplitude minimum, the third amplitude maximum and the third amplitude minimum are reset to zero values ​​for each of the three sampled signals (El).

6. Supervision method (100) according to claim 4 or 5, in which the reference power supply signal is a sinusoid of frequency equal to the power supply network frequency and having an amplitude equal to the reference alternating voltage.

7. Supervision method (100) according to any one of claims 2 to 6, wherein, during the determination step (DET), the at least one malfunction (DI; D2) is at least 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 the at least one sub-harmonic (SH11, SH21) is not included in the at least one second amplitude tolerance range, or - the amplitude of the at least one harmonic (Hll, H21, H31, H41) is not included in the at least one third amplitude tolerance range.

8. Supervision method (100) according to claim 7, in which the at least one malfunction (DI; D2) is determined as being an overload (Dl), 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 kl times the first amplitude maximum (Max 11), kl being a coefficient strictly greater than 1.

9. Supervision method (100) according to claim 8, in which the coefficient kl is between 1.2 and 1.

5.

10. Supervision method (100) according to any one of claims 7 to 9, in which the at least one malfunction (D1; D2) is determined as being a depriming 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. Supervision method (100) according to claim 10, in which the coefficient k2 is between 0.70 and 0.

98.

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

14. Supervision method (100) according to claim 12 or 13, wherein the at least one malfunction (DI; D2) is determined as being a disturbance of the power supply signal when, for the sampled signal associated with the power supply voltage: - the number of harmonics that it comprises during at least one second implementation ((j+l)R) of the set of steps (POS) becomes greater than the number of harmonics that it contained during at least one first implementation (jR) of the set of steps (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 - 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.

15. Supervision method (100) according to claim 14, in which the coefficient k3 is between 1.1 and 1.

5.

16. Supervision method (100) according to any one of claims 2 to 15, in which, during the determination step (DET), the at least one malfunction (DI; D2) is determined as being a reversal of 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. Supervision method (100) according to claim 16, in which the critical phase shift value is between 30° and 120°.

18. Supervision method (100) according to any one of claims 2 to 17, wherein the set of steps (POS) comprises 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 being: - a minor fault (dmi), with the centrifugal pump (2) commanded to continue operating following said categorization step; - a major fault (dMA), with the centrifugal pump (2) commanded to be temporarily stopped during a temporary downtime following the categorization step (WRN), then restarted once the temporary downtime has elapsed; - a critical fault (dCr), with the centrifugal pump (2) ordered to shut down following the categorization step (WRN).

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

20. Supervision method (100) according to any one of the preceding claims, in which, for each of the three sampled signals (El), the stability threshold associated with the at least one sub-harmonic (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 the at least one sub-harmonic (SH11, SH21).

21. Supervision method (100) according to claim 20, in which the coefficient k4 is between 0.01 and 0.

5.

22. Supervision method (100) according to any one of the preceding claims, wherein, for each of the three sampled signals (El), the at least one sub-harmonic (SH11, SH21) comprises: - a first sub-harmonic (SH11) at a first sub-harmonic frequency (FSH11) which is for example equal to the fundamental frequency (FOI; F02) divided by two; - a second sub-harmonic at a second sub-harmonic 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. Supervision method (100) according to any one of the preceding claims, wherein, for each of the three sampled signals (El), the at least one harmonic (Hll, 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 preceding claim, wherein the sampling frequency is between 500Hz and 1MHz.

25. A monitoring method (100) according to any preceding claim, 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. ​​Supervision 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 preceding claim, wherein the reference alternating voltage is equal to 230 VAC, or 400 VAC.

29. Supervision system (1) for supervising a centrifugal pump (2) driven by an asynchronous motor (21) and operating at a power supply network frequency, which supervision system (1) is 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 power 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 - a control unit (4) at least in communication with the measuring system (3); said control unit (4) comprising a memory, and a processor which is configured to execute a program for an implementation of the supervision method according to any one of claims 1 to 28.

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