Method for controlling and / or monitoring an operation of a pump system

Abstract

A, preferably computer-implemented, method for controlling and / or monitoring an operation of a pump system (1), wherein the pump system (1) comprises a pump (2) and a motor (3) that is connected to drive the pump (2), the method comprising the steps of: determining a plurality of cavitation indicators (10), wherein each cavitation indicator (11, 12) indicates cavitation or a likelihood of cavitation of the pump (2) for different operating ranges (21, 22, 31, 32), wherein each op- erating range (21, 22, 31, 32) is given by a combination of values of a first and a second motor characteristic.

Description

[0001] Description

[0002] TITLE

[0003] Method for controlling and / or monitoring an operation of a pump system

[0004] TECHNICAL FIELD

[0005] The present disclosure relates to the field of pump systems and the control and / or monitoring of the same .

[0006] BACKGROUND

[0007] When operating pumps , the undesirable phenomenon of cavitation occurs when the suction pressure is too low and this leads to boiling bubbles in the pumped medium . At the very least , unplanned work operations will be needed to maintain the pump system, e . g . , replace the impeller and / or housing of the pump .

[0008] From European patent application no . EP 21200024 . 4 it is known to measure the magnetic stray flux of an electric machine and to feed this magnetic stray flux into a simulation model of the electric machine . The simulation model determines operating parameters of the electric machine and analyses these operating parameters to identi fy faults in the electric machine .

[0009] From European patent application EP 2 196 678 Al a method and a system in accordance with a pump controlled with a frequency converter has become known . Therein, one or more features indicating cavitation or likelihood of cavitation of the pump are determined in order to detect cavitation or likelihood of the cavitation of the pump from one or more of the formed features . From US patent application US 2016 / 010639 Al a sensorless technique for pump di f ferential pressure and flow monitoring has become known .

[0010] From European patent application EP 1 198 871 Al a mal function detection of a machine driven with a variable rotational speed by an electric motor, whereby the motor is switched of f when a mal function occurs has become known . To this end, the machine and / or a unit actuated by the machine runs through all possible operating states in which the operating values of the motor recorded during the learning function are , in their association with the machine and / or the unit driven by the motor, stored, brought forward and used for monitoring mal functions .

[0011] SUMMARY Cavitation may lead to erosion of the impeller and / or housing and thus to the destruction of the pump . Prolonged operation of the pump during cavitation must be avoided at all costs .

[0012] It is thus desired to prevent interruptions ( and therefore expensive downtimes ) in a plant and ensure optimal motor load . It is also desired to prevent faults in the system and recogni ze impending failures before they happen .

[0013] It is thus an obj ect to enable a more accurate assessment of the operating status , possible changes and the distance of the operating point to an unwanted operation with cavitation .

[0014] The obj ect is achieved by the subj ect matter of the independent claims . Advantageous embodiments are provided in the dependent claims .

[0015] BRIEF DESCRITPTION OF THE DRAWINGS Figure 1 shows a pump system .

[0016] Figure 2 shows another pump system .

[0017] Figure 3 shows a visuali zation of cavitation indicators for di f ferent operating ranges .

[0018] Figure 4 shows a pump system and exemplary method steps .

[0019] Figure 5 shows visuali zations of a first and a second operating point and a curve of transient operating points between the first and second operating point .

[0020] Figure 6 shows visuali zations of cavitation indicators changing during the operation of the pump system .

[0021] Figures 7 to 15 show exemplary method steps .

[0022] DETAILED DESCRIPTION

[0023] In Figure 1 a pump system is shown . Pumps may be used in production plants within the process industries for conveying liquid fluids . A pump 2 may be combined with an electrical motor 3 driven by 3-phase alternating current (AC ) from a converter 6 . An actuator and / or sensor 4 in the pump system may together with the pump serve for generating and monitoring a defined ( controlled) flow of a liquid . A control unit 5 may serve for the automation of the pump system . To that end, the control unit may comprise control functions . For example , in the case of centri fugal pump, a PI flow control takes place via a downstream, continuously adj ustable proportional valve . The pump itsel f is controlled by the control unit ( di- rect starter) , e.g., SIMOCODE proffered by SIEMENS. A control device 7, such as an industrial PC, with a display may be coupled to the control unit 5. Motor characteristics, status values of the valve and / or measurement values form one or more sensors of the pump system, e.g., in the form of data, may be obtained by the operating device 7. The operating device 7 may then serve for further processing and / or visualizing the data obtained.

[0024] As shown in Figure 1, an actuator in the form of a valve may ensure that no liquid runs through the pump when it is switched off. The valve may also serve for controlling the pump load. The pump load is the back pressure and / or resistance to flow of fluids that the pump must overcome to force the fluid to flow through a pipeline, drill string, etc. Furthermore, in order to control the pump system, the flow rate, the inlet and outlet side pressures and / or the temperature of the liquid medium may be measured. A binary liquid detector is used to determine whether there is any liquid at all.

[0025] A plurality of characteristics of the pump system may be measured using one or more sensors. Hence, a plurality of sensor signals may be measured. For example, the electrical active power of the motor 3, the flow rate of the pumped medium, the input pressure (suction pressure) of the pump 2, the outlet pressure (delivery pressure) of the pump, and / or a binary signal indicating whether the motor is running may be determined. Additionally for cavitation monitoring the temperature of the pumped medium may need to be determined. In addition, in case of speed-controlled pumps, the pump speed may be determined. In case a converter 6 supplies the (shaft) power of the motor 3 the mechanical power may be determined. Further characteristics of the motor 3 may comprise nominal speed, nominal power, nominal efficiency. Characteristics of the pump 2 may comprise a minimum flow, a nominal flow, a delivery characteristic (H / Q characteristic) , a power curve (P / Q curve) , and / or an efficiency curve. Further characteristics may be determined, e.g., in case of a fluid other than water, a fluid specific vapor value may be determined.

[0026] A fault in the operation of a pump 2 may pose serious threats. Different monitoring and / or control functions may be relevant for the pump system dependent on the appropriate reaction and / or urgency. Diagnoses such as an acute blockage, dry running, and / or cavitation may be reported immediately to the plant operator as an alert, e.g., an alarm, since such operating conditions can quickly damage the pump. An automatic emergency stop of the pump and / or closing of a valve may then be initiated. In particular, operating states such cavitation may lead to damage to the pump after some time, but as a rule one still has to react relatively quickly. In this case, the diagnostic information may be reported to the plant operator and / or the maintenance engineer.

[0027] For example, in case the conveyed liquid is flammable, an explosive atmosphere can be built up inside the pump by the gas / vapor phase together with oxygen (e.g. from air ingress) . If cavitation occurs the material of propellers, valve discs or impellers is literally eaten away. In the case of machines at risk of cavitation, particularly hard and strong materials must therefore be used. Cavitation often results in a corrosive attack. Protective layers are removed and the roughened, porous surface offers optimal conditions for corrosion. Criteria for the occurrence of cavitation are mainly the cavitation number and the required net suction lift. The dimensionless cavitation number o is a measure of when in a fluid cavitation occurs. To avoid cavitation, the cavitation number o should be chosen as large as possible. The following measures reduce the cavitation tendency: avoid low pressures, avoid temperatures close to the boiling point of fluids, use thin blade profiles, choose a small angle of attack for the blades, avoid abrupt deflections of the flow, round off the leading edge.

[0028] Another criterion is the NPSH value (Net Positive Suction heads) . The NPSH value corresponds to the (pressure) energy of a liquid column under the existing operating conditions on connection flange. The value is always positive. A distinction is made between two NPSH values: NPSHA (Net Positive Suction Head Available) : This is the present pressure of the plant at operating conditions as a head difference. NPSHR (Net Positive Suction Head Required) : This is the pressure required to operate the pump as a height difference.

[0029] In Figure 2 another pump system is shown. Therein, a motor 3 drives the pump 2, wherein the motor is directly powered by a 3-phase alternating current (AC) mains line. For monitoring the operation of the pump system measurement values from one or more sensors, e.g., operatively coupled to the motor may be captured. Furthermore, motor characteristics may be determined. Said values may be read out from the motor or from a separate sensor, e.g., attached to the motor. For example, a control device 7, such as an industrial PC, may be communicatively coupled to the motor and / or separate senor. A pump and pump system may have one or more operating ranges. As described herein a pump or pump system may thus be operated in one or more of these operating ranges. For example, the pump system may comprise one or more acceleration phases and / or deceleration phases of the pump and / or motor, e.g., during the ramp-up and / or ramp-down of the motor / pump. In general, the pump (system) may have an allowable operating range which comprises the operating ranges. The operating ranges may be given by a combination of values of a first and second motor characteristic .

[0030] Now turning to Figure 3, a plurality of cavitation indicators is shown. Therein each cavitation indicator indicates cavitation or a likelihood of cavitation of the pump for different operating ranges, wherein each operating range is given by a combination of values of a first and a second motor characteristic. Thus, an operating range may be given by a plurality of values, e.g., an interval, of a first motor characteristic and a plurality of values, e.g., an interval, of a second motor characteristic. A cavitation indicator may take on discrete values. As shown in Figure 3 the cavitation indicator may take on 10 values. In addition, a value of the cavitation indicator may be reserved for a case in which no motor characteristics are available or for other reasons no cavitation indicator could be determined. For example, the motor characteristics may be motor speed, e.g., speed values, and motor load, e.g., load values. Thus, speed intervals (comprising speed value ranges) and load intervals (comprising load value ranges) may be determined which together form operating ranges. Therein an operating range may be given by associating a speed interval 21, 22 with a load interval 31, 32. As shown in Figure 3 this may result in a cavitation indicator 11 for a pairing of interval 21 with interval 31 and a second cavitation indicator 12 for the paring of interval 22 with interval 32. The allowable operating range may thus have cavitation indicators assigned to each or at least a plurality of the operating ranges. The resolution or width of the operating ranges may be chosen based on the frequency, update rate or sample rate of the speed values or load values available . As shown in Figure 3 the cavitation indicators may be visualized, e.g., in the form of a heatmap. The visualization may be presented to a user, e.g., on a display of the control device 7. A heatmap is created from the data at different operating points. This heatmap does not have to be completely filled.

[0031] Thereby, a more accurate assessment of the operating status, possible changes and / or the distance of the operating point to an unwanted operation with cavitation can be determined.

[0032] The cavitation indicator may be determined based on pump vibrations and / or magnetic flux. Hence, this may require a detection of pump vibrations and / or magnetic flux, e.g., in addition to the speed and / or load of the driving motor. The vibrations and / or magnetic flux (values) can be obtained, for example, via a sensor, such as the SIMOTICS Connect 400, attached to the pump and / or motor, using vibration and magnetic field sensors. Furthermore, the temperature of the conveyed medium may be measured or estimated by temperature measurement of the fluid or in the vicinity thereof. Characteristic values for the cavitation activity may then be determined from the vibration and / or magnetic flux signal.

[0033] Cavitation is the emergence and subsequent abrupt disappearance of vapor bubbles in the flow of a liquid. During the operation of pumps, such vapor bubbles can arise as a result of (locally) excessive flow speeds: the higher the speed, the lower the pressure in the liquid. If the pressure falls below the vapor pressure of the liquid, vapor bubbles form. If the pressure increases again in the direction of flow, the bubbles collapse: the gas in the bubble suddenly condenses. This implosion of the bubble results in so-called "jet impacts". Enormous pressure and temperature peaks occur, which are usu- ally many times higher than the load limits of the material of the pump blade or pump wall. The surface of the blade or wall is permanently damaged and eventually destroyed. In addition, even a small amount of cavitation reduces the efficiency (head) of the pump. Full cavitation can even lead to a complete collapse of production.

[0034] The cavitation indicator (s) may be determined based on vibration signals. Alternatively, other signals such as motor current, stray magnetic field of the motor and / or acoustic signals of a microphone can also be used to determine the cavitation indicators.

[0035] As shown in Figure 3 the cavitation indicator may take on discrete values on a scale which at one end indicates high cavitation or likelihood thereof and at the other end indicates low or no cavitation or likelihood thereof. One or more thresholds T1 may be determined for the cavitation indicator.

[0036] Advantageously, the data comprising speed values, load values, and / or vibration and / or magnetic flux values is recorded during a start-up of the pump system or over a, e.g., longer, period of time with varying load and speed. Different acceleration trajectories can also be used in order to capture a, e.g., large, area of the operating ranges. The vibration may be in a range of 0.1 Hz - 20 kHz. The acoustic sound may be in a range of 0.1 Hz - 100000 kHz. Furthermore, as described herein a pump or pump system may thus be operated in one or more operating ranges. For example, the pump system may comprise one or more transitional phases, such as one or more acceleration phases and / or one or more deceleration phases of the pump and / or motor, e.g., during the ramp-up and / or rampdown of the motor / pump. Thus, a transitional phase may comprise one or more operating ranges (given by values of the first and second motor characteristics ) . During such a transitional phase , the pump system, in particular the pump and / or the motor, may transition from one operating point or range to another operating point or range . Now, for example one or more measurements may be made during the transitional phase in order to obtain values of the first and / or second motor characteristic . Thus , during a transitional phase , values of the first and second motor characteristic may be obtained . Based on the values of the first and second motor characteristic a cavitation indicator may be determined . That is , for example , for one or more pairs of values of the first and second motor characteristic a cavitation indicator may be determined . The one or more cavitation indicators determined during the one or more transitional phases ( or based on the values of the first and second motor characteristic during the one or more transitional phases ) may be used to create and / or populate a database with entries relating to the one or more cavitation indicators associated with the respective operating ranges . Thus , even though the one or more values of the first and / or second motor characteristic have been determined during a transitional phase , these one or more (values of the ) first and / or second motor characteristics may be used for determining the one or more cavitation indicators , e . g . for the one or more operating ranges or points , for example comprised in or covered by the transitional phase . A transitional phase may arise due to changing operating conditions of the pump system . For example , based on a valve position, the load may be increased and / or based on a changed volumetric flow, the speed may be changed . Thus , for example a transitional phase may occur or may be initiated, e . g . , the valve position may be changed based on a control valve setpoint and / or the volumetric flow may be changed based on a speed setpoint . Similarly, the control valve setpoint and / or the motor speed setpoint may be changed in order to avoid any re- gions, i.e., one or more operating ranges with a respective cavitation indicator exceeding a predetermined cavitation threshold, e.g., when changing from a first operating point or range to a second operating point or range of the pump system, in particular of the pump and / or motor.

[0037] Figure 4 shows a pump system and exemplary method steps. A sensor 40 for detecting vibrations and / or magnetic flux of the motor may be attached to the motor or located in the vicinity of the motor 3. Hence, measurement values are obtained from the pump system. As described herein, the measurement values may be obtained by a control device which may further process the measurement values. Thus, based on the measurement values a cavitation indicator may be determined for each of the operating conditions present at the time the measurements were taken. For example, it may be necessary to obtain sufficient vibration and / or magnetic flux values in a certain operating range in order to determine a cavitation indictor for that operating range. However, the cavitation indicator may also be estimated, e.g., based on first and / or second motor characteristics. A database with entries relating to the operating ranges and cavitation indicators associated with the respective operating ranges may then be created. To that end, the database may be stored in a memory of the control device or in the memory of another device. The cavitation indicator may then be visualized, e.g., in the form of a heatmap, e.g., in order to assist a user, for example for controlling the pump (system) . Thus, a user may control the operation of the pump system, e.g., the motor and / or the pump, based on the plurality of cavitation indicators. Thus, the operation of the pump system, e.g., the motor and / or the pump, may be controlled, e.g., automatically, based on the plurality of cavitation indicators. That is, the operation may be controlled such that one or more operating ranges of the pump with a cavitation indicator exceeding a predetermined cavitation threshold are avoided. For example, the user may control the operation of the pump system based on a visualization of the cavitation indicators, e.g., by setting speed and / or load setpoints. In addition to the cavitation indicators the operating ranges, given by the combination of values of the first and second motor characteristic may be visualized, e.g., as the x-axis and y-axis.

[0038] Figure 5 shows visualizations of a first and a second operating point 01, 02 and curves Cl, C2 of (transient) operating points between the first and second operating point 01, 02.

[0039] As before, the axes correspond to speed and load of the motor driving the pump. However, other motor characteristics may be used. A first operating point 01, preferably corresponding to the present operating point of the pump, may have a first cavitation indicator assigned to it, which e.g., represents low or now cavitation or likelihood thereof. The first operating point 01 may correspond to and / or be within a first operating range. A second operating point, preferably an operating point to be reached, may also have assigned a second indicator to it. The second operating point 02 may correspond to and / or be within a second operating range. Now, according to the curve Cl the change of operating points requires the pump (system) to take on operating points at which cavitation and / or a high likelihood thereof occurs. Thus, a second curve C2 avoiding those operating points with high cavitation or likelihood thereof is determined. This second curve is determined such that it avoids operating points or corresponding operating ranges at which the cavitation indicator exceeds a threshold value, e.g., threshold value T1 of Figure 3. Hence, based on the operating ranges and the cavitation indicator assigned to (each of) the operating ranges it is possible to transitions between operating points that may cause cavitation to occur.

[0040] Figure 6 shows visualizations of cavitation indicators changing during the operation of the pump system. Again, cavitation indicators are determined for different operating ranges. During the operation of the pump system the behavior of the pump, i.e., its condition, may change. Hence, it may be necessary to update the cavitation indicators after a period of time, e.g., periodically or when an event occurs. As shown in Figure 6 at a first point in time tl, e.g., (directly) after commissioning the pump system, the cavitation indicators for a plurality of operating ranges are determined. After a , e.g., prolonged, operation of the pump system, at a second point in time t2 the cavitation indicators, e.g, for at least part, of the operating ranges are redetermined and / or updated. As shown in Figure 6, a comparison of the visualization of the cavitation indicators allows identifying that the cavitation behavior of the pump (system) has changed. Based on the comparison the control settings of the pump system may be adapted. Furthermore, in addition to anomaly detection, the operating condition or rather error condition of the pump, e.g., a damage to the impeller or to the guide wheel, or deposits in pipes, may be determined. Furthermore, changes to the process can also be derived based on the comparison.

[0041] Figures 7 to 15 show exemplary method steps. In a step SI a plurality of cavitation indicators may be determined. For example, the cavitation indicators may be calculated by a processor of an operating device. The cavitation indicators may be stored in a database. The database may be located in a memory of the operating device as well, i.e., the cavitation indicators are stored in the memory. In a step S2, it is determined whether a cavitation indicator (of the plurality of the cavitation indicators ) exceeds a predetermined cavitation threshold . The cavitation threshold may be set , e . g . , by a user and for example be based on experience , and / or the pump application, i . e . , the usage of the pump system .

[0042] A cavitation indicator and thus each cavitation indicator of the plurality of cavitation indicators determined indicates cavitation or a likelihood of cavitation of the pump . The occurrence of cavitation can not be determined with absolute certainty since it is dependent on the speci fic circumstances . Thus , the cavitation indicator may be interpreted as indicating a probability of cavitation .

[0043] Each cavitation indicator of the plurality of cavitation indicators may be determined for di f ferent operating ranges . Each operating range is given by a combination of values of a first and a second motor characteristic . For example , for an interval of values a representative value may be used, for example a median or mean value of the interval or range may be used as a basis for determining the cavitation indicator . Alternatively for all values of an interval or range the cavitation indicator may be determined and a mean or median value of the cavitation indicators may be used .

[0044] Each operating range may be given by a combination of values of a first and a second motor characteristic . The operating range may thus comprise individual values or may be an interval comprising multiple values . For example , an operating range may comprise a first value of the first motor characteristic and a first value of a second motor characteristic . Furthermore , an operating range may comprise multiple values of the first motor characteristic and multiple values of a second motor characteristic . The values of the first and second motor characteristic may be stored in a memory as de- scribed above and be associated with one another and / or with the cavitation indicator. This allows for a coarse-grained mapping of the cavitation of the pump system, e.g., within the allowable operating range of the pump (system) and / or the motor. Hence, the cavitation of the pump system may be determined in a granular fashion, i.e., granularly. To that end, the cavitation indicator may be determined, e.g., estimated, for each one of the plurality of operating ranges, e.g., within the allowable operating range of the pump (system) and / or the motor. The cavitation indicator of an operating range may be updated when the pump (system) and / or the motor is (actually) operated in the operating range or in one or more adjacent operating ranges.

[0045] In a step S3, an alert may be initiated in case the cavitation threshold is exceeded by one or more cavitation threshold of the plurality of cavitation threshold. For example, the alert may be displayed, e.g., on a display of the operating device. The alert may be a notification or an alarm and may comprise information about the one or more cavitation indicators exceeding the cavitation threshold.

[0046] Turning to Figure 8 further exemplary method steps are shown. In a step SO a vibration and / or a magnetic flux may be measured. The vibration and / or the magnetic flux may be generated by the motor. The measurement may be taken at different operating ranges. In a step SI, as before, the cavitation indicator (s) for the respective operating range (s) may be determined based on the vibration and / or magnetic flux measured.

[0047] Turning to Figure 9, in a step SI a plurality of cavitation indicators may be determined. Therein, the cavitation indicator may be a cavitation score, e.g., on cavitation scale. Hence in a step S4 a cavitation score may be determined. The cavitation scale may be a (discrete or continuous) cavitation scale, the cavitation scale indicating a first likelihood of cavitation at one end, e.g., cavitation present, and a second likelihood of cavitation, e.g., no cavitation present, on the other end.

[0048] Turning to Figure 10, in a step S5 a distance to one or more other operating ranges is determined. The distance may be between the operating range of the first operating point and one or more other operating ranges. The first operating point, or operating range, may be associated with no or a low cavitation indicator (e.g., below the cavitation threshold) . On the other hand, the first operating point may be associated with high / intermediate cavitation indicator.

[0049] The distance may be determined in terms of the first and / or second motor characteristic, e.g., given in units of the first and / or second motor characteristic, respectively. The one or more other operating ranges may be associated with or may possess a cavitation indicator that exceeds the predetermined cavitation threshold. Hence, the risk of the operating point of the pump system drifting towards a region of cavitation or likelihood thereof may be determined.

[0050] Thus, in a step S6, the control settings of the motor and / or the pump system may be adapted (automatically) based on the distance. The control settings of the motor and / or the pump system may relate to the first and / or second motor characteristic, preferably in order to arrive at an operating point with low / no cavitation indicator. The first motor characteristic may correspond to the motor speed and / or the second motor characteristic may correspond to the motor load (torque) . Turning to Figure 11, in a step S6, the control settings of the motor and / or the pump system may be adapted (automatically) , e.g., based on the distance, as described herein. In a step S7, this may comprise adapting the motor speed setpoint of the motor and / or adapting a control valve setpoint of a control valve of the pump system. The pump system may thus comprise a valve that controls the motor load (torque) .

[0051] Turning to Figure 12 further exemplary method steps are shown. In a step S8, a plurality of the cavitation indicators are determined during an acceleration phase and / or deceleration phase of the pump and / or motor. To that end, the corresponding measurements of the vibration and / or magnetic flux re also made during those phases, respectively. The acceleration phase (s) and / or deceleration phase (s) may correspond to the ramp-up and / or ramp-down of the motor / pump. This allows to capture the motor's and / or the pump's behavior over different and / or a plurality of operating ranges.

[0052] In a step S9, the cavitation indicators may be re-determined during the operation of the pump system. For example, for repeated acceleration phase (s) and / or deceleration phase (s) and / or after a predetermined period of operating time of the pump system. For example, at first point in time the cavitation indicator may be determined for one or more operating ranges and at later point in time the (and for the same or different operating ranges) the cavitation indicators may be redetermined .

[0053] Turning to Figure 13, as just described, in a step S9 the cavitation indicators may be redetermined during the operation of the pump system. In a step S10 the updated cavitation indicators may be compared with previously determined cavitation indicators, e.g., for the same or similar (e.g., over- lapping) operating ranges. In a step Sil, an operating condition of the pump / pump system may be determined based on the comparison, e.g., a damage of the pump and / or a deposition in a pipe of the pump inlet and / or pump out-let.

[0054] Turning to Figure 14, in a step S12 it may be determined, for example by a processor of an operating device, such as said control unit, whether the cavitation indicator of one or more, e.g., transient, operating points between a first and a second operating point exceeds the cavitation threshold value. The same applies to (transient) operating ranges between a first and a second operating range. Therein, the one or more (transient) operating points or operating ranges may be located on a curve, given by the first and second motor characteristic. The curve may connect the first and second operating points or operating ranges. Now, in case the operating points or operating ranges exhibit cavitation, i.e., the cavitation indicators of those (transient) operating points or operating ranges exceed the cavitation threshold (set) , such a curve may not be desired (for the pump system to be operated in) , since it is detrimental to the operating lifetime of the pump system. Thus, in a step S13, the curve may be adapted in case a cavitation indicator of the or more transient operating points exceeds the cavitation threshold value. In that case the curve may be adapted not to include (transient) operating points or (transient) operating ranges when the operation of the pump system is changed from the firs operating point to the second operating point. Furthermore, the cavitation indicator (s) of one or more operating points or operating ranges between the first and the second operating points or operating ranges may be interpolated. That is, given the cavitation indicator of the first operating point or operating range and the cavitation indicator of the second operating point or operating range, the cavitation indicator of an operating point or range between them may be determined based on the first and / or second motor characteristic of that in between operating point or range. Similarly, the cavitation indicator of one or more operating points or operating ranges may be interpolated and / or extrapolated based on at least a first and a second operating point or operating range, and preferably determining whether the interpolated and / or extrapolated cavitation indicator exceeds a cavitation threshold value, in particular wherein the one or more transient operating points or operating ranges are located on a curve, e.g., given by the first and second motor characteristic values, connecting the at least one first and second operating points or operating ranges.

[0055] Now turning to Figure 15, in a step SI as previously described, a plurality of cavitation indicators may be determined. In a step S14 the plurality of cavitation indicators and the corresponding operating ranges may be visualized, e.g., in the form of a heatmap, on a display, e.g., of an operating device, such as computer or a handheld.

[0056] It should be understood that the operating ranges, preferably are adjacent to each other and, cover (at least part of) the allowable operating range of the pump system and / or motor. That is, the operating ranges may cover the first and / or second motor characteristics present at nominal speed, nominal power, and / or nominal efficiency. The operating ranges may cover the first and / or second motor characteristic at a minimum flow, a maximum flow, a nominal flow, a delivery characteristic (H / Q characteristic) , a power curve (P / Q curve) , and / or an efficiency curve of the pump.

[0057] A further embodiment comprises a computer program comprising program code that when executed performs the method steps of any one of the embodiments described herein . A further embodiment comprises a, preferably non-transitory, computer readable medium comprising the computer program .

Claims

CLAIMS1. A, preferably computer-implemented, method for controlling and / or monitoring an operation of a pump system (1) , wherein the pump system (1) comprises a pump (2) and a motor (3) that is connected to drive the pump (2) , the method comprising the steps of: determining a plurality of cavitation indicators (10) , wherein each cavitation indicator (11, 12) indicates cavitation or a likelihood of cavitation of the pump (2) for different operating ranges (21, 22, 31, 32) , wherein each operating range (21, 22, 31, 32) is given by a combination of values of a first and a second motor characteristic.

2. The method according to the preceding claim, further comprising : determining whether the cavitation indicator (11, 12) of one or more operating points (01) of the motor (3) , given by a combination of values of the first and the second motor characteristic within an operating range (21, 22, 31, 32) , exceeds a predetermined cavitation threshold value (Tl) , initiating an alert in case the cavitation threshold value (Tl) is exceeded.

3. The method according to any one of the preceding claims, further comprising: wherein each operating range (21, 22, 31, 32) is given by a combination of a first range of values of the first motor characteristic and a second range of values of the second motor characteristic.

4. The method according to any one of the preceding claims, further comprising: measuring a vibration generated by the motor (3) and / or a magnetic flux generated by the motor (3) at different operating ranges, anddetermining the cavitation indicator (21, 22, 31, 32) for that operating range based on the vibration and / or magnetic flux measured.

5. The method according to any one of the preceding claims, further comprising: wherein the step of determining the cavitation indicator (21 ,22, 31, 32) at the different operating ranges comprises, determining a cavitation score on a (discrete or continuous) cavitation scale, the cavitation scale indicating a first likelihood of cavitation at one end, e.g., cavitation present, and a second likelihood of cavitation, e.g., no cavitation present, on the other end.

6. The method according to any one of the preceding claims, further comprising: determining for a first operating point within a first operating range, e.g., the first operating point associated with no / low cavitation indicator, a distance, e.g., in terms of the first and / or second motor characteristic, to one or more other operating ranges at which the cavitation indicator exceeds the predetermined cavitation threshold.

7. The method according to any one of the preceding claims, further comprising: determining for a first operating point within a first operating range, e.g., the first operating point associated with high / intermediate cavitation indicator, a distance, e.g., in terms of the first and / or second motor characteristic, to one or more other operating ranges at which the cavitation indicator does not exceed the predetermined cavitation threshold.

8. The method according to any one of the preceding claims, further comprising: adapting, based on the distance, the control settings of the motor and / or the pump system relating to the firstand / or second motor characteristic, preferably in order to arrive at an operating point with low / no cavitation indicator .

9. The method according to any one of the preceding claims, further comprising: wherein the first motor characteristic corresponding to the motor speed and / or the second motor characteristic corresponding to the motor load (torque) .

10. The method according to any one of the preceding claims, further comprising: adapting the motor speed setpoint of the motor and / or adapting a control valve setpoint of a control valve of the pump system, wherein the control valve controls the motor load (torque) .

11. The method according to any one of the preceding claims, further comprising: wherein the plurality of the cavitation indicators is determined during an acceleration phase and / or deceleration phase of the pump and / or motor, e.g., during the ramp-up and / or ramp-down of the motor / pump.

12. The method according to any one of the preceding claims, further comprising: re-determining, i.e., updating, the cavitation indicators during the operation of the pump system.

13. The method according to any one of the preceding claims, further comprising: comparing the updated cavitation indicators with previously determined cavitation indicators, and determining an operating condition of the pump / pump system based on the comparison, e.g., a damage of the pump and / or a deposition in a pipe of the pump inlet and / or pump outlet .The method according to any one of the preceding claims , further comprising : interpolating and / or extrapolating the cavitation indicator of one or more operating points or operating ranges given by at least a first and a second operating point or operating range , and preferably determining whether the interpolated and / or extrapolated cavitation indicator exceeds a cavitation threshold value , in particular wherein the one or more transient operating points or operating ranges are located on a curve , e . g . , given by the first and second motor characteristic values , connecting the at least one first and second operating points or operating ranges . The method according to any one of the preceding claims , further comprising : determining whether the cavitation indicator of one or more transient operating points or operating ranges between a first and a second operating point or operating range exceeds the cavitation threshold value , wherein the one or more transient operating points are located on a curve , given by the first and second motor characteristic, connecting the first and second operating point or ranges . The method according to any one of the preceding claims , further comprising : adapting a curve , e . g . , given by a first and second motor characteristic, and preferably connecting the first and second operating point or ranges , in case a cavitation indicator of the or more transient operating points or ranges exceeds the cavitation threshold value . The method according to the preceding claim, visuali zing the plurality of cavitation indicators and the corresponding operating ranges on a display . A pump system operative to perform the method steps according to any one of the preceding claims .

Images