RU2370783C2 - Electrometric device for contact-free measurement of current and depth of underground trunk pipeline bedding - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: device comprises unit of harmonic generator and measuring unit. Generator unit comprises the first and second quartz master generators with close frequencies, the first analog multiplier, parallel resonant circuit tuned for frequency equal to difference of frequencies in the first and second quartz generators, power amplifier. Metering unit comprises two measuring converters of magnetic field intensity into electric signal, which are installed along vertical line to pipe axis one under another, amplifier, analog-digital converter, two digital indicators, the third quartz master generator, frequency of which is equal to frequency of the second quartz generator, the second analog multiplier, quartz filter, analog commutator, microprocessor program-controlling controller.

EFFECT: improved noise immunity and accuracy of measurements.

1 dwg

Description

The present invention relates to the field of non-destructive testing (NDT) and technical diagnostics of underground oil and gas pipelines.

A device for non-contact detection of current leaks in a section of an underground pipeline, comprising a current source connected between the pipeline and the ground, four measuring sensors mounted on special tripods with racks, four orientation sensors, measuring amplifiers, switches, a subtracting unit, measuring and orientation indicators [ one]. Also known is a device for non-contact measurement of currents in underground pipelines, containing three one-component magnetic field sensors, an amplifier, three amplitude detectors, a constant voltage source, an analog-to-digital converter, a digital-to-analog converter, a two-way and three-position switch, and an indicator [2 ].

A common disadvantage of these devices is their low reliability due to the bulkiness of the design and complicated tuning technology.

Closest to the proposed invention is a non-contact seeker for damage to the insulation of communication, containing blocks for indicating current, depth of the object, the first and second transducers of the magnetic field into an electrical signal placed above the communication path on a vertical line to the path, so that the first converter is placed under the second; blocks of division, subtraction, multiplication, while the output of the first converter is connected to the first input of the subtraction unit and the multiplication block, the output of which is connected to the current display unit, and the second input is to the input of the unit for indicating the depth of the object and the output of the division unit, the first input of which is connected with the output of the subtraction block, and the second input with the second input of the subtraction block and the output of the second converter.

The disadvantages of this device are low noise immunity and low measurement accuracy due to the lack of frequency filtering of very strong electrical interference from radio transmitting stations, high-voltage transmission lines of electrical energy, underground cable communications. The use of analog blocks of mathematical processing of the measured signals leads to low accuracy of their measurement parameters.

The aim of the present invention is to increase the noise immunity of the device and the accuracy of measuring the parameters of the pipeline.

This goal is achieved due to the fact that the electrometric device for non-contact measurement of current and the depth of the underground main pipeline, containing a block of harmonic oscillation generator located vertically to the pipe axis one below the other two measuring transducers of the magnetic field into an electric signal, amplifier, analog a digital converter, two digital indicators, a set of blocks of division, subtraction, multiplication, differs in that it is additionally equipped with three quartz sets generators, two analog multipliers, a parallel resonant circuit, a power amplifier, a quartz filter, an analog switch, a microprocessor programmable controller, while in the generator block the outputs of two master crystal oscillators are connected to the inputs of the first analog multiplier, the output of which is through a parallel resonant circuit and a power amplifier is supplied to the pipeline, and the outputs of two measuring transducers are connected to the inputs of the analog switch d which is connected to the first input of the second analog multiplier, to the second input of which is connected the output of the third master quartz oscillator, the output of the multiplier is connected to the series-connected crystal filter, an amplifier, an analog-digital converter; at the same time, the microprocessor controller is connected to the switch, amplifier, analog-to-digital converter and two digital indicators through the address bus and data bus, and the microprocessor controller performs the functions of the division, subtraction, and multiplication blocks programmatically.

The block diagram of the device shown in figure 1

The device consists of a generator block (Fig. 1a), containing quartz oscillator oscillators 1 and 2, an analog multiplier 3, a frequency filter in the form of a parallel resonant circuit 4, and a power amplifier 5. The generator is connected by a potential terminal to a metal terminal connected to the surface and connected to the pipeline metal input, and grounding terminal with the soil surrounding the pipeline ("ground").

The measuring unit of the device (figb) consists of two converters 7 and 8 of the magnetic field to an electric signal, an analog switch 9, a second analog multiplier 10, a third crystal oscillator 11, a crystal filter 12, an amplifier 13, an analog-to-digital converter 14, two digital indicators 15 and 16 and a microprocessor program-controlling controller 17. The device operates as follows. Frequency selection is organized in a special way. The frequencies f ₁ and f _{2 of the} first two quartz master oscillators 1 and 2 are chosen close enough, taking into account that their difference Δf = f ₁ -f ₂ is equal to about 1 kHz (for example, 973.5 Hz). At higher frequencies, the measurement error increases due to the stronger effect of soil conductivity. It is very difficult to obtain a lower difference frequency Δf, since industrial quartz is not produced with closer frequencies.

After multiplying the two voltages of the master oscillators 1 and 2 at the output of the multiplier 3, a signal is obtained in the spectrum of which there will be signals with frequencies equal to the sum and difference of the multiplied frequencies.

By tuning the parallel resonant circuit 4 to a frequency Δf = f ₁ -f ₂ , a low-frequency signal is obtained, which is fed through a power amplifier 5 to a controlled pipeline. The current excited in the pipeline creates an alternating electromagnetic field in the environment, the intensity of which is converted at the output of the converters 7 and 8 into two electrical signals U ₁ and U ₂ recorded by the measuring unit of the device. In this case, the low-frequency signals U ₁ and U ₂ through the switch 9 are fed to the analog multiplier 10, where, using the third quartz master oscillator 11 with a frequency f _{2, they are} again converted into signals with frequencies equal to the sum and difference of the multiplied frequencies (f ₂ and Δf). The output signal after the multiplier 10 will contain the frequencies Δf ₂ = f ₂ + f ₁ -f ₂ and Δf ₃ = f ₂ -f ₁ + f ₂ = 2f ₂ -f ₁ . Using a quartz filter 12 tuned to a frequency f ₁ , very narrow-band signals with the total frequency of the multiplied signals are extracted. This method of a narrow-band measuring circuit is due to the fact that quartz resonators with a frequency of less than 32 kHz are not produced by industry. And the most effective method of suppressing electrical noise is a sharp decrease in the bandwidth of the measuring circuit. Informative signals from the output of the multiplier 10 through a quartz filter 12, an amplifier 13 (with an adjustable gain) and an analog-to-digital converter 14 in a digital code are transmitted via a data bus to a microprocessor controller.

The measured parameters of the pipeline are calculated by the formulas:

occurrence depth

,

,

current flowing through the pipeline:

,

,

where K ₀ - conversion factor of the magnetic field into the amplitude of the signal;

l is the distance between the transducers 1 and 2.

Measurements are taken when the device is located above the center of the pipeline.

The values of h and I are presented in digital form on indicators 15, 16.

Information sources

1. Copyright certificate No. 1821758, G01R 31/02. Published 06/15/93, bull. Number 22.

2. Copyright certificate No. 1746320, G01R 19/00. Published July 7, 1992 Bul. Number 25.

Claims (1)

A device for non-contact measurement of the current and the depth of the underground main pipeline, comprising a harmonic oscillation generator unit and a measuring unit, including two measuring transducers of magnetic field strength vertically to the pipe axis, into an electrical signal, an amplifier, an analog-to-digital converter, two digital indicator, characterized in that the block of the harmonic oscillation generator contains the first and second quartz master oscillators, the first analog a multiplier, a parallel resonant circuit, a power amplifier, the measuring unit further comprises a third quartz master oscillator, a second analog multiplier, a quartz filter, an analog switch, a microprocessor program-control controller, while in the generator block the outputs of the first and second master quartz oscillators having similar frequencies are connected to the inputs of the first analog multiplier, the output of which is through a parallel resonant circuit tuned to a frequency equal to the difference h the frequency of the first and second crystal oscillators, and a power amplifier connected to the pipeline, the outputs of two measuring transducers are connected to the inputs of the analog switch, the output of which is connected to the first input of the second analog multiplier, the second input of which is connected to the output of the third master crystal, the frequency of which is equal to the frequency a second crystal oscillator, the output of the multiplier being connected to a series-connected crystal filter tuned to the frequency of the first crystal generator, an amplifier, an analog-digital converter, the microprocessor controller through the address bus and data bus is connected to a switch, an amplifier, an analog-digital converter and the two digital displays.