Method for monitoring a hydraulic system for anomalies, such as leaks, and hydraulic system comprising a controller configured for carrying out the method

Abstract

The invention relates to a method for monitoring a hydraulic system, in particular a pressure-boosting system, comprising at least one centrifugal pump and a pump controller, wherein the centrifugal pump is activated and deactivated by the controller as required. The invention is characterized in that the number of activation and / or deactivation processes of the pump over at least one specified monitoring period is counted and compared with a reference value. An anomaly within the hydraulic system is inferred on the basis of the comparison result.

Description

[0001] Description

[0002] Method for monitoring a hydraulic system for anomalies such as leaks and hydraulic system with a controller configured to carry out the method

[0003] The invention relates to a method for monitoring a hydraulic system, in particular a pressure boosting system, with at least one centrifugal pump and a pump control, wherein the centrifugal pump is switched on and off by the control as required.

[0004] Pressure boosting systems are used to raise the fluid pressure to a specific target pressure level within a hydraulic system. A classic example of a pressure boosting system is its use in a building's drinking water supply. Here, the fluid pressure within the system must be kept constant at a target pressure level so that end users can be supplied with sufficient pressure or the fluid can be drawn off at the desired pressure via tapping points.

[0005] Such pressure boosting systems often operate with demand-based control, also known as "standby mode." During standby mode, the pump within the system is switched on and / or off depending on current demand. Pressure control is typically used. If the system pressure falls below the target pressure, the pump is activated until the target pressure is reached.

[0006] Typically, water withdrawal during the night, especially in public buildings, is comparatively low, so the system pressure either never drops or drops relatively rarely. In an intact hydraulic system, i.e., a theoretically leak-free system, the pressure should therefore not drop at all, or at least only drop very slowly. This typically leads to either no restarts or only a comparatively low number of pump restarts.

[0007] Taking this finding into account, the object of the present invention is to develop a simple monitoring method that enables monitoring and detection of anomalies based on the above-described characteristics of hydraulic systems.

[0008] This object is achieved by a method according to the features of claim 1 and a hydraulic system or centrifugal pump according to claim 16 or claim 17. Advantageous embodiments of the method are the subject of the dependent claims.

[0009] According to the invention, the number of pump activations and / or deactivations is recorded over at least a specific monitoring time window, preferably at night, and compared with a reference value. Depending on the comparison result, for example, if the recorded number deviates from the reference value, the system assumes an anomaly within the hydraulic system.

[0010] For the process implementation, it is sufficient to count only the pump start-ups, as these are triggered by a pressure drop in the system. However, for the process implementation, it is also possible to consider only the stop-ups or even the number of both start-ups and stop-ups.

[0011] Advantageously, a leak in the hydraulic system can be detected as an anomaly. Leaks typically lead to undesirable pressure losses and thus to an increasing number of start-up cycles. Leakage is not only defined as a loss of volume from the piping system of the hydraulic system, but also as an undesirable leakage flow through a shut-off device, such as a valve or check valve.

[0012] As already described above, the demand-based switching on and off of the pump can be controlled depending on a hydraulic parameter. If the current actual pressure in the system or on the pressure side of the pump falls below a setpoint pressure, for example, the control system switches the pump on. It is also conceivable for the frequency converter of the motor control system to monitor the flow rate. In the event of low flow rates, i.e. when a partial load limit or a switch-off speed is reached, the pump or the pump's drive motor is switched off. As soon as fluid is drawn from the system, the system pressure drops. If an adjustable limit for the maximum control deviation of the pressure control is reached, the pump switches on again. Alternatively, the pump can also be switched off depending on the pressure, i.e. the centrifugal pump is switched off when a setpoint pressure is reached or exceeded.

[0013] The reference value according to the invention, against which the number of switching operations is compared, can be specified manually by the user, for example, or instead be permanently stored in the system. However, it is preferred and more useful if the reference value is variably adjustable or even dynamically determined through a learning process.

[0014] As part of a learning process, which is preferably carried out after commissioning of the system or pump, an application-optimized reference value can be determined. It is precisely after commissioning that the probability that the system will function properly and that no leaks will occur is highest. During the learning process, an attempt is made to determine the expected number of switch-on and / or switch-off processes with a functioning system, which is then used as a reference value for subsequent monitoring or to determine the reference value. It is conceivable, for example, that the learning process determines the number of switch-on and / or switch-off processes of the centrifugal pump during at least one definable learning time window and either uses this number directly as a reference value or determines a reference value based on this number.The learning time window represents a specific, ideally continuous, period of time within a day. Ideally, the learning time window is set for a phase of the day during which experience has shown that a low or at least reduced number of switching on and / or off processes can be expected. For example, in the case of a pressure boosting system for the drinking water supply in a building, particularly a public building, it can be assumed that no or only a small amount of water is drawn during the night. Any pressure losses that occur are therefore minimal and the number of times the pump is switched on and / or off is reduced to a minimum or approaches zero. Based on this, it can also be assumed that the number of switching on and / or off processes during this time window will remain almost constant over several days, i.e. significant deviations are not normally to be expected during this time.

[0015] A reliable reference value can therefore be determined for this period.

[0016] Theoretically, it is sufficient to record the number of switching operations on and / or off during a single learning time window, for example, several hours at night. However, to optimize the reference value generation, it is preferable to determine the number of switching operations on and / or off multiple times, especially for a definable number of periodically repeating learning time windows, i.e., over several days. For the repeated determination of the individual values, the average and / or median can then be calculated and used as a reference value. In this way, event-related outliers can be averaged out.

[0017] As already mentioned above, such a learning time window can be defined by a specific number of hours in a specific part of the day. A suitable learning time window for a public building could, for example, be a period from 9:00 p.m. to 6:00 a.m. The learning time window can be defined manually by the user or permanently stored in the control system. According to an advantageous embodiment, it is also conceivable that the learning time window is optimized by an adaptive learning algorithm. In this context, it is conceivable, for example, for such an algorithm to determine the frequency distribution of the switching on and / or off processes within the initially defined learning time window or a plurality of periodically repeating learning time windows.The learning time window is then reduced by those periods characterized by a particularly high frequency of switching on and / or off. It is also conceivable that the time period with the lowest frequency of switching operations is selected for the new learning time window. For example, the initial learning time window could be defined from 8:00 p.m. in the evening to 7:00 a.m. in the morning. However, depending on the building, there may still be comparatively high drinking water consumption in the early evening hours, so that increased water withdrawal with a frequency of pump switching on and / or off above a threshold can be detected especially in the period from 8:00 p.m. to 11:00 p.m. In the evening, the pump can be switched on and / or off more frequently than a threshold value. By determining the frequency distribution, only the period from 11:00 p.m. to 7:00 a.m. in the morning could then be considered for the adaptively optimized learning time window.The number of switching on and / or off operations is then determined at least once for this new time window in order to determine the reference value.

[0018] It is also conceivable that, in addition to the frequency distribution, other parameters may be taken into account for the adaptive determination of the learning time window. For example, information about the type of hydraulic system or the specific application and its installation location can be important. For example, it may be crucial whether the building supplied by the system is a public building, which experience shows is used during the day, or whether it is private residential space, where increased drinking water consumption can be expected during the evening or night hours. This knowledge can also be used to optimize the learning time window. According to the preferred embodiment, the monitoring time window is determined after the reference value has been determined. The monitoring time window is sensibly defined in line with the previously defined learning time window.However, there is theoretically nothing to prevent deviations between the monitoring time window and the learning time window.

[0019] Even for ongoing monitoring during regular plant operation, it is generally sufficient to determine the number of pump activations and / or deactivations during a monitoring time window and compare them with the reference value. Comparing an average number or a median of activations and / or deactivations over a number of periodically repeating monitoring windows with the reference value also has the advantage of eliminating any outliers.

[0020] The stated average value or median value can be determined after a predefined number of monitoring time windows and then compared with the reference value. It is conceivable and preferred to determine a moving average value or median value, which is always calculated from a specific number of past monitoring windows. After a certain number of monitoring windows, such a value is calculated for the first time and then continuously updated after each subsequent monitoring time window.

[0021] When comparing the number of switching operations on and / or off during at least one monitoring window with the reference value, it is conceivable that an anomaly or leakage is assumed if the reference value is exceeded. However, it is conceivable to only assume an anomaly if the value is exceeded by a configurable minimum percentage, for example, if the reference value is exceeded by at least 10%, preferably at least 15%, particularly preferably at least 20%.

[0022] Upon detection of an anomaly or leak, the controller can generate and optionally output a warning message. Such a warning message can be generated acoustically and / or visually. It is also conceivable for the controller to transmit such a warning message to a third-party device, a central location, or the cloud via a communication channel.

[0023] It is conceivable that, in addition to the number of switching operations on and / or off, the respective duty cycle should also be taken into account, i.e., the duration for which the pump is actively running after being switched on. The duty cycle can, for example, be summed over a monitoring time window. Taking into account the operating time during a monitoring time window may, under certain circumstances, make it possible to differentiate between a regular switching-on reason and a switching-on reason due to a leak, since a significantly higher volume of drinking water is usually withdrawn during regular drinking water withdrawal than is the case due to a leak in the pipe network.

[0024] The basic idea of ​​the present invention is essentially based on the detection of individual switching on and / or off processes, with the pump here providing demand-based control, in particular pressure control. In this context, it is also conceivable for the pump to be switched on and off as required, but instead the volume flow delivered by the pump is recorded using a volume counter, in particular a volume counter integrated into the pump control system. In particular, the volume delivered is recorded within a specific monitoring time window and compared with a reference value, which was also determined as a normal case within a learning time window. Depending on the comparison result of the two volumes, it is then possible to determine whether there is an anomaly or a leak within the hydraulic system.It can be assumed that if a leak occurs in the system, an increased volume is pumped, which can then be detected by comparing the actual volume during a monitoring time window with a reference value.

[0025] Considering the duty cycle can also be useful in conjunction with monitoring the pumped volume within a monitoring time window. In addition to the method according to the invention, the present invention also relates to a hydraulic system, in particular a pressure boosting system, preferably for the drinking water supply of a building, with at least one centrifugal pump and a pump control system. The invention also encompasses a centrifugal pump with a corresponding pump control system. According to the invention, the pump control system is configured such that it can carry out the method according to the invention as described above.

[0026] Further advantages and features of the invention will be explained in more detail below with reference to the figures. They show:

[0027] Figure 1 : a diagram showing the number of detected switching operations over time and

[0028] Figure 2: a diagram showing the moving median value of the counted switch-ons over time.

[0029] The diagram in Figure 1 shows a diagram in which the x-axis shows the number of days and the y-axis shows the number of start-ups per learning / monitoring time window. The series of measurements was created as an example for a pressure boosting system in a public building. At least one centrifugal pump is used in the hydraulic system with a large number of water extraction points to increase the pressure. At least one pump is controlled according to demand, i.e. the system should provide a target pressure that is as constant as possible. If the pressure falls below a target value, the pump is switched on; if there is no or only a slight reduction, the pump is switched off.

[0030] In the measurement series shown here, the monitoring time window is selected to be identical to the learning time window, and the switch-on processes occurring between 9 p.m. and 6 a.m. are counted each day. After the system is commissioned, a learning process 10 is initially performed. The number of switch-on processes within the defined time window is counted for a total of eleven days. The time window used, from 9 p.m. to 6 a.m., is considered the learning time window. The mean or median value is then calculated from the total of fourteen individual values ​​counted and used as the reference value 20 for subsequent monitoring.

[0031] For monitoring purposes, the monitoring time window is defined identically to the learning time window, meaning that the power-on events between 9 p.m. and 6 a.m. are always counted. However, the daily value is not compared to the predetermined reference value; instead, the median value from a measurement series over a definable number of days is always used. This means that for a measurement series, the number of power-on events for, say, 14 days is summarized, and the median value is calculated from this.

[0032] Figure 2 shows such a diagram, in which the median value for a number of fourteen days is plotted against time. Furthermore, the plotted median value is a moving average, which is always determined for the past fourteen days.

[0033] Also shown in Figure 2 is the previously determined reference value 20, which here assumes the value of three. For detection, the median value must exceed this reference value by at least 10% before a warning message is recognized and issued. The corresponding threshold is marked with reference numeral 30 in Figure 2. In the illustration in Figure 2, the median value exceeds threshold 30 for the first time after day 37 of monitoring, and a warning message is generated by the system.

Claims

Patent claims Method for monitoring a hydraulic system for anomalies such as leaks and hydraulic system with a controller configured to carry out the method 1 . Method for monitoring a hydraulic system, in particular a pressure boosting system, with at least one centrifugal pump and a pump control, wherein the centrifugal pump is switched on and off by the control as required, characterized in that the number of switching on and / or off operations of the pump is counted over at least one specific monitoring time window and compared with a reference value, wherein an anomaly within the hydraulic system is concluded depending on the comparison result.

2. Method according to claim 1, characterized in that the anomaly is a leak in the hydraulic system.

3. Method according to one of the preceding claims, characterized in that the demand-based switching on and / or off takes place depending on a hydraulic parameter, in particular the pump is switched on when the pressure in the system falls below a target value and is switched off when the demand falls below a minimum flow rate.

4. Method according to one of the preceding claims, characterized in that the reference value can be specified manually by the user or is determined during a learning process of the centrifugal pump.

5. Method according to claim 4, characterized in that during the learning process the number of switching on and / or off operations of the centrifugal pump during at least one learning time window is determined and set as a reference value or used to set the reference value.

6. Method according to claim 5, characterized in that the average number or the median value of the switching on and off processes is formed over a definable number of periodically repeating learning time windows and is defined as a reference value or is used to define the reference value.

7. Method according to one of the preceding claims 5 or 6, characterized in that the learning time window for the learning process is determined adaptively.

8. The method according to claim 7, characterized in that the frequency distribution of the switching on and off processes within the learning time window or a plurality of periodically repeating learning time windows is determined and preferably those time ranges are excluded for the adaptive optimization of the learning time window which have a high or the highest frequency of switching on and off processes, in particular the frequency is above a threshold value.

9. Method according to one of claims 7 or 8, characterized in that for the adaptive determination of the learning time window, further parameters are taken into account, such as the type of hydraulic system or the installation location of the hydraulic system.

10. Method according to one of the preceding claims 5 to 9, characterized in that the monitoring time window is coordinated with the learning time window, in particular with the previously adaptively determined learning time window.

11. Method according to one of the preceding claims, characterized in that the average number or the median value of switching on and off operations is determined over a definable number of periodically repeating monitoring windows and compared with the reference value.

12. Method according to claim 11, characterized in that the average number or the median value is a moving value.

13. Method according to one of the preceding claims, characterized in that an anomaly, in particular a leak, is detected when the number of switching on and / or off operations during a monitoring window or the determined average number or the median value exceeds the reference value, in particular by at least an adjustable proportion, for example by at least 10%, preferably at least 15%, particularly preferably by at least 20%.

14. Method according to one of the preceding claims, characterized in that the control system generates a warning message upon detection of an anomaly, which is signaled acoustically and / or visually and / or transmitted to a third device via a communication channel.

15. Method for monitoring a hydraulic system with at least one centrifugal pump and a pump control, wherein the centrifugal pump is switched on and off by the control as required, characterized in that the volume pumped by the pump is recorded over the duration of at least one monitoring time window and compared with a reference value, wherein an anomaly within the hydraulic system is concluded depending on the comparison result.

16. Hydraulic system, in particular pressure boosting system, preferably for the drinking water supply of a building, with at least one centrifugal pump and a control system configured to carry out the method according to one of the preceding claims.

17. Centrifugal pump with a pump control configured to carry out the method according to the steps of one of claims 1 to 15.

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