SU1765693A1 - Method of measuring vibrations of water surface - Google Patents

Description

 yes., t-t -; - S Ј.

(21T4853462710

(22) 06.20.90

(46) 09/30/92. Bul Number 36

(71) Leningrad branch of the State Design and Survey and Scientific Research Institute of the Marine Transit Company

(72) P.M.Bogolyubov

(56) USSR Copyright Certificate Mg 129836, cl. G 01 C 13/00, 1959.

(54) METHOD OF MEASURING VIBRATION LEVELS OF AQUEOUS SURFACE

(57) Application: the method of measuring fluctuations in the level of a water surface belongs to the field of hydro physical measurements and to be used in the fields of science and technology that require measurements of the level of liquid electrically conductive media. SUMMARY OF THE INVENTION: The method includes the following actions: the working and reference electrode pairs are supplied with alternating current in a range of 10-1500 Hz. Set the frequency of the current feeding the reference electrodes FOO and the frequency Fpo of the current feeding the working electrodes. The voltage drop Uoo is measured at the reference electrodes and iro at the working electrodes. When the voltage drop db of U01 values on the reference and Upi on the working electrodes, caused by a change in temperature and / or salinity, changes the electrical quantities functionally related to the electrical conductivity of the medium (the frequency of the current supplying the electrodes and / or the value of the supply current of the electrode system) ) until the full compensation of the named changes in the voltage drops on the reference and working electrodes. The voltage drop across the working electrodes is measured, due only to a change in the level of the water surface. The performance of the compensation is checked by performing the equality of the frequency ratios: Fpi: F01 Fpo: FOO and / or the voltage drops Dpi: Upo U01: Uoi. 2 Il.

(L

WITH

The invention relates to the field of hydrophysical measurements and can be used in the fields of science and technology that require measurements of fluctuations in the level of the water surface. ; vQ There are known methods for measuring sea level fluctuations that use the dependence of the electrical parameters of an electrode system buried in water on the degree of its immersion (see Conductometric method. Vasyutinsky I.Yu. Hydrostatic leveling. M .: Nedra, 1976, p.86).

The named method is based on the use of the complex conductivity of water,

 S-riSJitart-; “IZFFA

highly dependent on temperature fluctuations and the concentration of salts dissolved in it, which leads to measurement errors comparable to the measured value.

There is a known method for measuring waves and water level (see Erasmus Pepevac. Measuring waves and water level by analog and digital systems using liquid-liquid resistive probes // Meeting of the heads of water authorities of the CMEA member countries. Modern methods and devices for measuring hydraulic and hydrological elements; xj about e

Oj

Comrade The Symposium of Bulgaria-Varna, 1974, p.252).

The method consists in using the change in the electrical resistance of the two string electrodes included in the measurement circuit. A signal proportional to the degree of immersion of the electrodes is amplified and fed to the recorder. To compensate for the effect of temperature on the measurement results, a thermistor located in close proximity to the electrodes is used, and the thermistor is electrically connected to the feedback circuit of the information signal amplifier so that the effect of water temperature fluctuations on the measurement results is compensated.

The disadvantages of the above method include the dependence of measurement results on the concentration of salts dissolved in water, as well as the presence of an error in compensating for temperature changes due to the fact that the laws describing the dependence of the output conversion value on the degree of immersion of the electrodes and on the change in water temperature are different and different. linear.

The method described above is closest to the claimed one in terms of essential features and adopted as a prototype.

To increase the measurement accuracy, it is necessary to eliminate the contributions to the change in the resistance of the electrode system from changes in temperature and salinity (concentration of dissolved salts).

The aim of the invention is to improve the measurement accuracy by compensating for the contribution to the change in the resistance of the electrode system from temperature and / or salinity by using the reactive component of the sea resistance.

The purpose of the invention is achieved by the fact that in a known method of measuring fluctuations in the level of a water surface based on the dependence of the electrical resistance of an electrode system partially immersed in water, the degree of immersion is used to measure only the reactive component of the impedance, for which the electrodes are fed with alternating current in the range frequencies between 10 and 1500 Hz (the range of the predominance of the reactive component of the impedance over the active).

At the initial constant level of the water surface, the frequency of the current supplying the fully immersed reference electrodes (F0o) and the frequency of the current (Fpo) are set

power supply of working electrodes, the voltage drop Uoo on the working electrodes and Upo on the reference electrodes are measured when the supply voltage of the electrode systems is set, when the voltage drop changes to the value U01 on the reference and UP1 on the working electrodes caused by the temperature change and / or salinity, change the electrical values, functionally related to the electrical conductivity of the medium (frequency F, supplying the electrodes, and / or the value of the supply current of the reference electrode system), after which changes in voltage drop across barrels

5 electrodes, due only to changes in the level of the water surface.

To ensure ease of use, they reduce the number of variable parameters, for example, only

0, the value of the frequency of the current supplying the reference and working electrodes (F01 and Fpi), the Foi frequency being determined when the voltage drops Uoo and Uoi are equal, and the Fpi value is determined from the equality of the ratios Fpi; Foi

5 Fpo: F oo, where Fpo, F01 and F0o are measured frequency values, Or the reference and working electrodes are supplied with a current of the same fixed variable frequency, compensating for voltage drop Upi

0 on the working electrodes, due only to changes in the physical properties of water and satisfying the equality of the ratios UP1: Upo Uoi: Uoo, and the compensation is effected, for example, by changing the current,

5 supplying the working electrodes by changing the supply voltage.

To improve the measurement accuracy of the proposed method, due to the localization in space of the reference and working measurements, the reference and working electrode systems are combined in space, with the electrode system working at different points in time as a system of reference electrodes and as a system of working

5 electrodes, for which in the first case only the underwater part of the electrodes is connected to the AC source, and in the second case both the underwater part and the surface part are connected. The invention is explained by the graph of the dependence of the voltage drop across the electrodes on the frequency of the supply current at fixed values of salinity and temperature shown in FIG. one.

Comparative analysis of the claimed

5 of the invention and the prototype reveals their difference already at the level of the physical entity. Indeed, the known method of measuring fluctuations in the level of a water surface is based on measuring the resistance of an electrodes-water system with changes in the level of a water surface. In this case, only the active component of the complex resistance of water is used, the so-called. ohmic resistance. However, the reactive component of the complex resistance of water is not a value that is negligible in comparison with the active component. The reactive component depends on the concentration of salts dissolved in water and the temperature, and the neglect of this component leads to a measurement error comparable to the measured value.

The proposed method for measuring fluctuations in the level of a water surface consists in using only the reactive component of the water impedance. To use only the reactive component, select the appropriate frequency range of the current supplying the electrodes, an area of 10-1500 Hz, the so-called. relaxation region for the formation of migrating diffuse ions.

It is known that ions dissolved in water are in constant thermal motion (diffuse), when applying an electric field to a water sample, diffuse ions are oriented along the field, which requires time r and additional energy. Oriented in their movement across the field, the ions are the migrating ions. When the direction of application changes, the ions change the direction of movement, which also requires additional energy costs, which are the reactive (imaginary) part of the complex energy. The reciprocal of the time spent on the formation of migrating ions is the relaxation frequency fp.

The relaxation frequency fp is a physical characteristic of the medium. When the relaxation frequency and the frequency of the alternating electric field imposed on the sample are equal, the maximum (excess) absorption of the electric field energy occurs, i.e. dominated by the reactive component of energy.

The left-handed branch of the graphs (see FIG. 1) is a relaxation region characterized by the fact that each value of the voltage drop proportional to the water resistivity can be assigned a set of salinity and temperature values, or each frequency value can be assigned a variety of values for salinity, temperature, and field strength (voltages at the electrodes).

The graphs in FIG. 1 are described by a known analytical expression.

2i3i

ten

-four

and

KR -T F

0)

where IZI is the water impedance modulus;

U is the voltage drop across the electrodes of the electrolytic cell;

T is the absolute temperature of the medium;

F is the frequency of the electric field;

K is the equilibrium constant of the reaction for the formation of migrating ions, depending on the concentration of dissolved salts;

R is a universal gas constant;

2.39 -10 4 conversion factor.

From the above expression it can be seen that the resistance of medium Z in the advertising area can be changed by changing the frequency of the field, the supply current, or the voltage U, proportional to the supply voltage of the electrodes.

Equation (1) expresses the law on which the proposed method is based.

If the salinity or temperature changes in the process of measuring the fluctuations of the water surface level, the resistivity modulus IZI will also change. In this case, to compensate for the above change in resistance, you should change the voltage U, or the frequency F, until the previous value of IZI is restored. The above equation (1) is valid only for the relaxation region.

Writing equation (1) for the reference and controlled environment under the initial and changing conditions, we obtain a system of four equations

I

2.39 10

-four

(Joo

K R T

oo

oo

Izo1 i

2.39 10

-four

uЈi

K R T01 F01

IZpo I

2.39 10 U§

po

K R T

po t-po

..., 2.39 10 4 llSi IZp1 - K R TP1 Fpi

55

where the indices oo are the reference environment, the initial conditions;

o1 - supporting environment, changing conditions;

ro - controlled environment, changing conditions

the solution of which gives ratios, which are conditions under which compensation is carried out for changes in the resistance of the medium caused by changes in its salinity and / or temperature.

Comparison of the proposed technical solution not only with the prototype, but also with other technical solutions in this field of science and technology did not allow revealing into them the signs that distinguish the claimed solution from the prototype, which allows to conclude that the criterion of essential honors

The invention is illustrated by graphs (Fig. 1) and Figs. 2 a and b, which show block diagrams of devices for implementing the proposed method, where Fig. 2a:

1. The source of alternating current (tunable frequency generator).

2. Switch.

3. Fully submerged electrolytic cell electrodes (reference electrodes).

4. Partially immersed string-type electrodes (working electrodes).

5. Registering device, for example a digital voltmeter.

On figb:

1 and 2 - sources of alternating current feeding the electrode system in the mode of reference and working measurements.

3. Switch.

4. String-contact electrode system.

5. Registration device.

The proposed method can be implemented, for example, using a known device, a block diagram of which is shown in Fig. 2a, as follows: at a constant level, partially immersed (working) string-type electrodes 4 are placed at the level control point. In the immediate vicinity of the working electrodes, completely immersed (reference) electrodes 3 are arranged, made, for example, in the form of rectangular metal plates, as in a known electrolytic cell. To the output of an alternating current source 1 with a tunable frequency, which is used, for example, by a generator of standard audio signals, working electrodes 4 are connected via switch 2. Using generator 1, set the frequency of the current feeding the working electrodes to Fpo in the range of 10-1500 Hz The voltage drop Upo is measured on the working electrodes, for example, using a standard digital voltmeter 5. Using the switch 2, the reference electrodes 3 are connected to the output of the generator 1. The current frequency is set

supplying the electrodes equal to the value of Foo, set the voltage of the supply of the reference electrodes so that the voltage drop across them is equal to Uoo. At constant values of salinity and / or

0 temperature the voltage drop across electrodes 3 and 4 does not change. When the level of the water surface changes, its value is linearly related to the change in voltage drop at the working electrodes 4, according to which the level change is judged.

With possible changes in salinity and / or temperature, changes in the voltage drop Uoo on the reference electrodes 3 are monitored with a voltmeter 5. If

0, the named voltage drop is observed, and, for example, the new value Dot is adopted, the voltage drop Upo on the working electrodes 4 to the value Upi changes, which leads to a nonlinear dependence of the voltage on the voltage level. In this case, the change in the voltage drop Upi is compensated, for which a new value of the frequency of the current supplying the reference electrodes 3 (i.e., the generator frequency 1 equal to F0i) is set, at which the voltage drop on the reference electrodes Uoi takes the previous value Uoo i.e. the resistance value of the medium was the same, and the change in Upi was compensated by changing the frequency of the current feeding the working electrodes 4 to an Fpi value, which is determined from the ratio Fpi: Fo1 Fpo FOO.

Using switch 2, working electrodes 4 are connected to the output of generator 1. A new value of frequency Fpi is set at which the change in voltage drop UP1, caused by changes in salinity and / or temperature, is compensated.

5 Using a voltmeter 5 connected to the electrodes 4, the change in voltage drop caused only by a change in level is recorded. Resistance change compensation can be made and

0 when the condition expressed by the ratio Upi: U Po U 01: Uoo is fulfilled, for which, at the initial constant level, the reference electrodes 3 are connected to the output of the generator 1 via the switch 2,

5 fixed frequency F0o current feeding the reference electrodes. The output voltage of the generator 1 is set to Eoo (the supply voltage of the electrode system). In this case, the voltage drop across the electrodes is U0o. Connect the output

generator 1 using switch 2 to the working electrodes 4. At frequency F0o, the output voltage of the EPO generator is set so that the voltage drop on the electrodes 4 is Upo, which is measured with a voltmeter 5. The change in the resistance of the medium (conductivity) is monitored changes in salinity and / or temperature, for which, using a switch 2, reference electrodes 3 are connected to the output of generator 1. A voltage drop across them is measured with a voltmeter 5.

In the case of a change in salinity and / or temperature, the voltage drop changes, for example, takes the value U01, while the voltage drop on the working electrodes 4 also changes. The voltage drop change on the working electrodes 4 is compensated, for which using a switch 2 k the output of the generator 1 connect the working electrodes 4.

The supply voltage of the electrodes 4 is left unchanged, equal to Еро, and the frequency of the current feeding the electrodes 4 is set equal to Fpi, and the named frequency is determined from the above frequency ratio.

The earlier equality of the ratios of the voltage drops on the working and reference electrodes is a condition for compensating the resistance of the medium by changing the supply current of the electrode system, for example, by changing the supply voltage of the electrodes. In order to perform the above compensation, the reference and working electrodes are supplied with alternating current of a fixed equal frequency F. Using the switch 2, reference electrode electrodes 3 are connected to the output of generator 1. Set the output voltage of generator 1 (voltage of reference electrodes) I so that the voltage drops on electrodes 3 was equal to U0o. The output of the generator 1 is switched by means of the switch 2 to the input of the working electrodes 4. The output voltage of the generator 1 (EPo) is set so that the voltage drop on the electrodes 4 is equal to Upo. Control the change in water conductivity caused by a change in salinity and / or temperature, for which the output electrodes 1 are connected to the output of the generator 1 using switch 2; In the event of a change in the voltage drop U0o to the value Dob and Upo to Dpi as a result of changing only the physical properties of the water equality of relations between the named voltage drops, compensate for the change in voltage drop

working electrodes caused by a change in the resistance of the medium caused by variability of salinity and / or temperature by changing the supply current of the working electrodes, for which the working electrodes 4 are connected to the generator 1 through the switch 2, and a new value of the supply voltage of the electrode system EP1 is set (output voltage of the generator 1 ),

where the compensation of the voltage drop to the Upo value occurs. After compensating for the above voltage drop with Upi with a voltmeter 5, a change in voltage drop is proportional to

changes in the level of the water surface

The proposed method can also be implemented using a known string-contact electrode system, which

allows to increase the accuracy of measurements due to localization in the space of reference and working measurements. At the same time for the operation of the string-contact system as reference electrodes to the generator 1 through

the switch 2 connects the links of the string-contact electrode located under water. The value of the voltage drop Uoo and its variation is measured with a voltmeter 5. As working electrodes

use the links of the string-contact pair, located both above water and under water, for which the above links through the switch 2 is connected to the output of the generator 1. Compensation of the resistance of the medium

(voltage drops on the electrodes) are carried out under the conditions of equality of the ratios of frequencies and / or voltage drops.

40

Claims (1)

Invention Formula A method for measuring fluctuations in the level of a water surface at which two reference and two working electrodes are placed in controlled medium, set a fixed frequency of the current supplying the electrodes Fpo, control the voltage drop on the reference electrodes and measure the voltage drop on the working electrodes, which are used to judge the level change, characterized in that, in order to improve the measurement accuracy by eliminating the influence No changes of the controlled medium on its conductivity, set a fixed frequency of the supply current of the reference electrodes Foo equal to 100 Hz, and before measuring the voltage drop on the working electrodes change the frequency of the current supply the reference electrodes to the value F01 corresponding to the initial value of the voltage drop on the reference electrons of the working electrodes Fpi, determined by trades, and set the frequency of the power supply- from the ratio Fpi (Fpo -F0i) / Foo. V, i i  five i-s, 14 FIG. one. M XD CM