HYDRAULIC MACHINE WITH MONITORING SYSTEM

Description

[0001] The subject matter of this invention is a hydraulic machine which is designed to be subjected to a forced flow of water, wherein the hydraulic machine has a rotor with a plurality of blades or buckets which is surrounded by a housing.

[0002] In hydraulic machines, and especially in Pelton turbines, abrasion can alter the natural frequency of the impeller. This is particularly true when sediment-rich water is used to operate the turbine, as abrasion occurs on the buckets. This loss of mass changes the turbine's natural frequency. For the safe operation of a turbine, it is crucial that the natural frequency is not a multiple of the excitation frequency. For example, if a Pelton impeller rotates at a frequency of 10 Hz and is actuated by six nozzles, the excitation frequency is 60 Hz. If the impeller's natural frequency is a multiple of this, such as 600 Hz, it can lead to significant vibrations, which can ultimately even destroy the impeller (resonance catastrophe). Therefore, during impeller manufacturing, care is taken to ensure that the natural frequency is not a multiple of the excitation frequency.Changes in the natural frequency during operation can therefore be very problematic. The impellers must therefore be stopped and inspected at regular intervals; this is a complex process that takes one to three days.

[0003] An example of a hydraulic machine with an impeller is shown in document EP 3 006 729 A1.

[0004] The invention is therefore based on the objective of providing a hydraulic machine that is monitored with regard to its natural frequency without having to stop the turbine.

[0005] This task is solved by a hydraulic machine with a measuring arrangement according to claim 1.

[0006] According to the invention, at least one stationary position sensor is arranged in the housing. This position sensor is located next to the path of movement of the blades or buckets, and emits a measurement signal as a blade or bucket passes by, enabling precise position determination of the respective blade or bucket. Additionally, a reference sensor is arranged in the hydraulic machine, preferably in the area of ​​the turbine shaft. This reference sensor determines the current angular position of each blade or bucket. From this position data, the dynamic behavior of each blade or bucket can be determined. This means that the vibrations and / or amplitudes of the individual blades or buckets can be determined, allowing conclusions to be drawn about the natural frequency of the turbine. The natural frequencies can be determined through specific signal analyses.

[0007] If, for example, the mass of the blades or buckets or the stiffness changes during operation due to abrasion or cracks, and thus the natural frequency, this can be detected by this measurement without having to stop and inspect the turbine.

[0008] The measurement can be performed continuously throughout the entire operation or at regular intervals.

[0009] To ensure reliable data analysis, it is advantageous if data acquisition takes place in the MHz range.

[0010] Preferably, at least two position sensors are arranged in the housing. This significantly increases the measurement accuracy.

[0011] Protecting the sensors from water is important.

[0012] The invention is particularly well suited for Pelton wheels, which are typically supplied with water via at least one nozzle. It is advantageous if the position sensor(s) are located in the nozzle housing.

[0013] However, it is also conceivable that the rotor is a Francis turbine, a pump turbine, or a Kaplan turbine. The hydraulic machine could also be a pump.

[0014] The invention is described below with reference to a drawing.

[0015] Figure 1Figure 1 shows a section of a rotor 7 of a Pelton turbine 1 with the monitoring system according to the invention. Here, two position sensors 5 are arranged one behind the other in a nozzle housing 4 of the Pelton turbine 1. It is also conceivable that only one position sensor 5 is provided, or that only one position sensor 5 is provided per nozzle 3, with two or more nozzle housings 4 having one position sensor 5. However, more than two position sensors can also be mounted on one nozzle.

[0016] The two position sensors 5 successively detect the position of the cups 2. This position measurement, in combination with the reference sensor which determines the current angular position of the runner 7, allows the position of each cup 2 to be determined very precisely. If a cup 2 vibrates, this changes the measurement signals, allowing conclusions to be drawn about vibrations or vibration amplitudes and ultimately also about the natural frequency of the runner 7. The deflector 6, or cutter, for spray water redirection is located in the area of ​​the nozzle end. Reference sign

[0017] 1 Pelton turbine 2 Cup 3 Nozzle 4 Nozzle housing 5 Position sensor 6 Deflector or cutter 7 Runner

Claims

1. Hydraulic machine through which a forced flow of water flows, the hydraulic machine having a runner(7) and a housing surrounding the runner (7), the runner (7) having a plurality of vanes or buckets (2), characterized in that at least one fixed position sensor (5) is arranged in the housing, the position sensor (5) being arranged next to the path of movement of the vanes or buckets (2), so that it emits a measurement signal when a vane or bucket (2) passes, and a reference sensor preferably being arranged on a turbine shaft, whereby the current angular position of each vane or bucket (2) can be determined, so that the dynamic behaviour of each vane or bucket (2) can be determined from this position data.

2. Hydraulic machine according to Claim 1, characterized in that the position sensor (5) acquires the measurement data in the kHz or MHz range.

3. Hydraulic machine according to claim 1 or 2, characterized in that at least two position sensors (5) are arranged in the housing.

4. Hydraulic machine according to claim 1, characterized in that the position sensor or sensors (5) are protected against splashing water.

5. Hydraulic machine according to one of claims 1 to 3, characterized in that the runner (7) is a Pelton runner, which can be acted upon by water from at least one nozzle.

6. Hydraulic machine according to claim 5, characterized in that the position sensor (5) is arranged in the nozzle housing (4).

7. Hydraulic machine according to any one of claims 1 to 3, characterized in that the runner (7) is a Francis runner.

8. Hydraulic machine according to any one of claims 1 to 3, characterized in that the hydraulic machine is a pump turbine.

9. Hydraulic machine according to any one of claims 1 to 3, characterized in that the hydraulic machine is a pump.

10. Hydraulic machine according to any one of claims 1 to 3, characterized in that the hydraulic machine is a Kaplan turbine.