阅读说明：本技术 一种确定水轮机动静干涉振动能量的方法 (Method for determining dynamic and static interference vibration energy of water turbine ) 是由 王治国 王贵 陶星明 覃大清 李志和 钟苏 李伟刚 任光辉 李全胜 于 2020-07-02 设计创作，主要内容包括：本发明公开一种确定水轮机动静干涉振动能量的方法。通过对水轮机的振动和压力脉动试验测试,对得到的水轮机的动静干涉频率进行振动和压力脉动能量谱分析与统计,当振动能量和压力脉动能量在水轮机上游侧到下游侧的各个部件统计规律一致时,确定水轮机各部位的动静干涉频率的振动能量。本发明可以应用于水轮机各部位的动静干涉频率的振动能量的确定,以便对动静干涉振动的能量进行评估,避免水轮机运行时的动静干涉振动对水轮机厂房和机组的固定部件造成破坏,保证发电机组长期稳定运行。(The invention discloses a method for determining dynamic and static interference vibration energy of a water turbine. Through vibration and pressure pulsation test tests of the water turbine, vibration and pressure pulsation energy spectrum analysis and statistics are carried out on the obtained dynamic and static interference frequency of the water turbine, and when the statistical rules of the vibration energy and the pressure pulsation energy of all parts from the upstream side to the downstream side of the water turbine are consistent, the vibration energy of the dynamic and static interference frequency of all parts of the water turbine is determined. The method can be applied to the determination of the vibration energy of the dynamic and static interference frequency of each part of the water turbine so as to evaluate the energy of the dynamic and static interference vibration, avoid the damage of the dynamic and static interference vibration of the water turbine during the operation to the fixed parts of a plant and a unit of the water turbine, and ensure the long-term stable operation of the unit.)

1. A method for determining the vibration energy of the dynamic and static interference of a water turbine is characterized in that: the method comprises the following steps:

1) arranging acceleration vibration sensors on a water guide pipe, a top cover, a volute, a taper pipe, the inner side and the outer side of an elbow pipe and a draft pipe of the water turbine in four directions of + X, -X, + Y, -Y, and a volute, picking up vibration signals, converting the measured vibration signals into voltage signals of 0-5V, receiving the voltage signals by a data collector, and measuring the main frequency of vibration of each part of the water turbine in a dynamic state;

2) differential pressure transmitters are arranged at the inlet of a volute, between a guide vane and a rotating wheel and between the guide vane and the rotating wheel and between a bottom ring and the rotating wheel and between a top cover and the rotating wheel and between the fixed guide vane and a movable guide vane, and on the upstream side of an elbow pipe and a 0.4D taper pipe and on the downstream side of the 0.4D taper pipe, pressure pulsation signals are picked up to convert the measured pressure pulsation signals into voltage signals of 0-5V, and the voltage signals are received by a data acquisition unit to measure the main frequency of pressure pulsation of each part of the hydraulic turbine in a dynamic state;

3) carrying out comparative analysis on the vibration frequency and the pressure pulsation frequency measured by the water turbine, determining whether the measured vibration frequency and the pressure pulsation frequency are consistent, and obtaining the test dynamic and static interference vibration frequency of the water turbine when the measured vibration frequency and the pressure pulsation frequency are consistent;

4) carrying out energy spectrum density analysis on dynamic and static interference vibration frequency of the water turbine measured in four directions of a water conduit, a top cover, a volute, X, Y and Y, the inner side and the outer side of a taper pipe and an elbow pipe and a draft tube, and counting energy spectrum density of each part under each working condition to obtain an energy value;

5) carrying out energy spectrum density analysis on dynamic and static interference pressure pulsation frequencies of the water turbine measured at positions of a volute inlet, a position + X between a guide vane and a rotating wheel, a position + Y between the guide vane and the rotating wheel, a position + X between a bottom ring and the rotating wheel, a position + X between a top cover and the rotating wheel, a position between a fixed guide vane and a movable guide vane, an elbow, a 0.4D upstream side of a taper pipe and a 0.4D downstream side of the taper pipe, and counting energy spectrum densities of all the positions under all working conditions to obtain energy values;

6) and comparing and analyzing the vibration energy and the pressure pulsation energy measured by the water turbine from the upstream side to the downstream side, determining the statistical distribution rule consistency of the measured vibration energy and the pressure pulsation energy in each part, and obtaining the dynamic and static interference vibration energy of each part of the water turbine when the statistical distribution rule consistency is consistent.

Technical Field

The invention relates to the field of water turbine vibration, in particular to a method for determining dynamic and static interference vibration energy of a water turbine.

Background

Currently, for determining the stability performance of the water turbine, mainly the vibration amplitude and the vibration speed are evaluated, but the method has certain limitations. The vibration amplitude and the vibration speed can only reflect the influence of different exciting force frequencies on the system due to the dynamic characteristics of the system, and the vibration energy can comprehensively reflect the comprehensive influence of different exciting force frequencies on the system, so that the system is more comprehensive and objective.

For the dynamic and static interference vibration of the water turbine, the vibration amplitude and the vibration speed of the water turbine cannot accurately describe the vibration energy of the water turbine, so that when the dynamic and static interference vibration is measured, the vibration energy of a flow passage component or a fixed component of the water turbine needs to be analyzed by a power spectral density statistical method or an energy spectral density statistical method. Particularly, in the design and test stages, the magnitude of the dynamic and static interference vibration frequency energy of the movable guide vane of the water turbine is accurately identified, and the method is of great significance for judging the harmfulness of the dynamic and static interference vibration.

Disclosure of Invention

The invention aims to provide a method for determining dynamic and static interference vibration energy of a water turbine so as to solve the problem of the dynamic and static interference vibration energy of the water turbine. The technical scheme of the invention is as follows:

1) arranging acceleration vibration sensors on a water guide pipe, a top cover, a volute, a taper pipe, the inner side and the outer side of an elbow pipe and a draft pipe of the water turbine in four directions of + X, -X, + Y, -Y, and a volute, picking up vibration signals, converting the measured vibration signals into voltage signals of 0-5V, receiving the voltage signals by a data collector, and measuring the main frequency of vibration of each part of the water turbine in a dynamic state;

2) differential pressure transmitters are arranged at the inlet of a volute, between a guide vane and a rotating wheel and between the guide vane and the rotating wheel and between a bottom ring and the rotating wheel and between a top cover and the rotating wheel and between the fixed guide vane and a movable guide vane, and on the upstream side of an elbow pipe and a 0.4D taper pipe and on the downstream side of the 0.4D taper pipe, pressure pulsation signals are picked up to convert the measured pressure pulsation signals into voltage signals of 0-5V, and the voltage signals are received by a data acquisition unit to measure the main frequency of pressure pulsation of each part of the hydraulic turbine in a dynamic state;

3) carrying out comparative analysis on the vibration frequency and the pressure pulsation frequency measured by the water turbine, determining whether the measured vibration frequency and the pressure pulsation frequency are consistent, and obtaining the test dynamic and static interference vibration frequency of the water turbine when the measured vibration frequency and the pressure pulsation frequency are consistent;

4) carrying out energy spectrum density analysis on dynamic and static interference vibration frequency of the water turbine measured in four directions of a water conduit, a top cover, a volute, X, Y and Y, the inner side and the outer side of a taper pipe and an elbow pipe and a draft tube, and counting energy spectrum density of each part under each working condition to obtain an energy value;

5) carrying out energy spectrum density analysis on dynamic and static interference pressure pulsation frequencies of the water turbine measured at positions of a volute inlet, a position + X between a guide vane and a rotating wheel, a position + Y between the guide vane and the rotating wheel, a position + X between a bottom ring and the rotating wheel, a position + X between a top cover and the rotating wheel, a position between a fixed guide vane and a movable guide vane, an elbow, a 0.4D upstream side of a taper pipe and a 0.4D downstream side of the taper pipe, and counting energy spectrum densities of all the positions under all working conditions to obtain energy values;

6) and comparing and analyzing the vibration energy and the pressure pulsation energy measured by the water turbine from the upstream side to the downstream side, determining the statistical distribution rule consistency of the measured vibration energy and the pressure pulsation energy in each part, and obtaining the dynamic and static interference vibration energy of each part of the water turbine when the statistical distribution rule consistency is consistent.

The main problems to be solved by the invention are as follows:

1. testing the vibration and pressure pulsation test of the water turbine, and accurately obtaining the vibration and pressure pulsation energy spectrum analysis and statistical data of the dynamic and static interference frequency of the water turbine;

2. and when the statistical laws of the vibration energy and the pressure pulsation energy of each component from the upstream side to the downstream side of the water turbine are consistent, identifying the vibration energy of the dynamic and static interference frequency of the water turbine.

Principle of operation

For the dynamic and static interference vibration of the water turbine, the vibration amplitude and the vibration speed of the water turbine cannot accurately describe the vibration energy, so that when the dynamic and static interference vibration is measured, the vibration energy of a flow passage component or a fixed component of the water turbine needs to be analyzed by a power spectral density statistics or energy spectral density statistics method, so that the hazard of the dynamic and static interference vibration on the safety of the water turbine can be accurately evaluated.

Energy spectral density refers to the energy variation or variation of a signal or time series along with the frequency distribution, no matter whether f (t) is a finite energy continuous or discrete signal, the spectral density of the signal

All can be described by the square of the Fourier transform amplitude, and the main expression is

Wherein F (w) is f_nContinuous or discrete-time Fourier transform of^*(w) is the conjugate function of F (w), and w is the angular frequency. For discrete f_nIf the number of values defined is finite, the sequence can be considered periodic, using a discrete Fourier transform to obtain a discrete spectrum, or extended with zero values so that the spectral density can be calculated as in the case of an infinite sequence.

The method is mainly based on the paseuler's theorem, which mainly relates the calculation of the energy or power of the signal to a spectral function or spectrum, i.e. the total energy of the energy signal is equal to the integral of the energy contributed by each frequency component in the frequency domain alone, and the average power of the periodic power signal is equal to the sum of the average powers contributed by each frequency component alone.

Energy is denoted by E and power by P, in the frequency domain:

where w is 2 pi f, e (w) is the energy spectral density function, and p (w) is the power spectral density function, where the energy spectral density is the sum of the squared amplitudes of the unit frequencies, and the area under the energy spectral density curve is the total energy of the signal. The energy spectrum is the convolution of a power spectral density function on the phase and is also the integral of the square of an amplitude spectral density function on the frequency, the power spectrum is the Fourier transform of a signal autocorrelation function, the energy spectrum is the square of the Fourier transform amplitude of a signal, and generally, if the total energy of the signal is limited, the energy spectrum density function is used for inspection; if the total energy of the signal is infinite, but the energy per unit time is finite, such as a periodic signal, the energy is examined as a function of the power spectral density.

The method comprises the steps of obtaining dynamic and static interference vibration frequency of the water turbine through vibration and pressure pulsation test tests of the water turbine, carrying out vibration and pressure pulsation energy spectrum analysis and statistics on the obtained dynamic and static interference frequency of the water turbine, and determining the vibration energy of the dynamic and static interference frequency of the water turbine when the statistical rules of all parts of the vibration energy and the pressure pulsation energy from the upstream side to the downstream side of the water turbine are consistent.

Drawings

FIG. 1 is a block diagram of a vibration test measurement system for dynamic and static interference frequency of a water turbine

FIG. 2 is a block diagram of a pressure pulsation test measurement system for dynamic and static interference frequency of a water turbine

FIG. 3 is a vibration energy spectral density analysis data statistics of dynamic and static interference frequency of each part of the water turbine under rated output opening condition

FIG. 4 is a pressure fluctuation energy spectrum density analysis data statistics of dynamic and static interference frequency of each part of the water turbine under rated output opening working condition

FIG. 5 is an operational flow for implementing the present invention

Detailed Description

1) As shown in fig. 1, acceleration vibration sensors are arranged on a draft tube, a top cover, a volute, a top cover, a volute, a top cover, a volute, a top cover;

2) as shown in fig. 2, differential pressure transmitters are arranged at the inlet of a volute, between a guide vane and a rotating wheel + X, between the guide vane and the rotating wheel + Y, between a bottom ring and the rotating wheel + X, between a top cover and the rotating wheel + X, between a fixed guide vane and a movable guide vane, between an elbow pipe and a taper pipe 0.4D upstream side and between the taper pipe 0.4D downstream side, and a pressure pulsation signal is picked up to convert the measured pressure pulsation signal into a voltage signal of 0-5V, and the voltage signal is received by a data acquisition unit to measure the main frequency of pressure pulsation of each part of the hydraulic turbine in a dynamic state;

3) carrying out comparative analysis on the vibration frequency and the pressure pulsation frequency measured by the water turbine, determining whether the measured vibration frequency and the pressure pulsation frequency are consistent, and obtaining the test dynamic and static interference vibration frequency of the water turbine when the measured vibration frequency and the pressure pulsation frequency are consistent;

4) as shown in fig. 3, energy spectrum density analysis is performed on the dynamic and static interference vibration frequency of the water turbine measured in four directions of the water conduit, the top cover, the volute casing, the top cover, the volute casing, the top cover, the volute casing;

5) as shown in fig. 4, energy spectrum density analysis is performed on dynamic and static interference pressure pulsation frequencies of the water turbine measured at the inlet of the volute, the positions + X between the guide vane and the rotating wheel, the positions + Y between the guide vane and the rotating wheel, the positions + X between the top cover and the rotating wheel, the positions between the fixed guide vane and the movable guide vane, the positions on the elbow, the upstream side of the taper pipe 0.4D and the downstream side of the taper pipe 0.4D, and energy spectrum densities of all the positions are counted under all working conditions to obtain energy values;

6) comparing and analyzing the vibration energy and the pressure pulsation energy measured by the water turbine from the upstream side to the downstream side, determining the consistency of the statistical distribution rule of the measured vibration energy and the pressure pulsation energy in each part, and obtaining the dynamic and static interference vibration energy of each part of the water turbine when the measured vibration energy and the pressure pulsation energy are consistent, as shown in fig. 5, in order to realize the operation process of the invention.