RU2663555C1 - Method for checking the group of measuring instruments in the manufacturing facility by technological process observations - Google Patents

Abstract

FIELD: measurement technology.SUBSTANCE: method for verification of a group of measuring instruments in a production facility based on observations of the technological process refers to the field of measurement technology and is intended for verification and calibration of measuring instruments installed at pipeline transport facilities. Method is carried out by measuring the fluid flow parameters by standard measuring instruments. Values of systematic errors are sought by solving the problem of conditional optimization, the objective function of which is formed in accordance with the least-squares method and is a weighted sum of squares of deviations in the results of the fluid flow parameters measurements, corrected for systematic errors from the true values of these quantities. Limitations are a mathematical model of the pipeline system, as well as the correlations linking the model coefficients which characterize the technical condition of the system equipment, and the correlations linking the variances of the random components of measurement errors.EFFECT: verification of a set of measuring instruments installed on the pipeline system during their operation (for stationary and non-stationary modes of fluid flow) without installing additional diagnostic and / or measuring equipment and without special preparation for testing.1 cl, 3 dwg

Description

FIELD OF THE INVENTION

The invention relates to the field of measuring equipment and can be used for verification and calibration of measuring instruments installed on the objects of pipeline transport.

State of the art

Known methods of verification of measuring instruments [GOST R 8.906-2015; RU 2573452 C2, 01.20.2016; RU 2390741 C1, 05.27.2010], based on a comparison of their readings with measurements of exemplary instruments in laboratory conditions. The device to be verified is connected to special equipment and tests are carried out according to known methods.

A disadvantage of the known methods is their complexity, due to the need to remove the device to be verified from the facility in operation, to deliver the device to the laboratory for verification, to return it at the end of the test and to install it in place.

Known methods of verification of measuring instruments at the place of operation.

Some methods, for example [RU 2282836 C2, 08/27/2006; RU 2217704, 11.27.2003], based on a comparison of the testimony of verified and reference measuring instruments by known methods.

The disadvantage of these methods is the need to install and maintain additional (exemplary) devices.

The implementation of other methods [RU 2182320, 05/10/2002; RU 2373506 C1, 11/20/2009; RU 2358250 C2, 06/10/2009] requires the installation of special devices and / or special tests.

Their disadvantages are the costs of the purchase and installation of additional equipment, and in the case of special tests - violation of the operating mode of the technological facility, the required time and labor costs.

All of the listed methods of calibration of measuring instruments are designed to verify either one measuring instrument or several measuring instruments that are examined independently of each other. The choice of an exemplary device, special equipment, test methodology, etc., depends on the physical quantity that the device under test measures.

Closest to the claimed invention (prototype) is a method of calibration of measuring instruments [RU 2428708, 09/10/2011], which takes into account the systematic nature of the problem being solved - it checks the set of measuring instruments installed in the technical system on interconnected measurement objects. The known method consists in the multiple measurement by a summing measuring device of the sum of the quantities that are measured by verified measuring devices. The results of all measurements are recorded. The systematic errors of measuring instruments are found by solving a system of linear algebraic equations connecting the measurement results.

The disadvantages of this method are the need to install and maintain a summing measuring device with a higher accuracy class, as well as a limited scope. The known method cannot be used for checking pressure gauges, thermometers and other devices for which there are currently no summing devices that can measure the sum of the quantities they measure. The known method cannot be applied during unsteady fluid flow in a pipeline system for checking instruments that measure the operational parameters of a fluid flow (flow rate, thermal energy, etc.), because in this case, the equality of the readings of the summing measuring device and the sum of the readings of the calibrated measuring devices obtained for one moment in time is not performed.

Disclosure of invention

The basis of the present invention is the creation of a method of verification and calibration of measuring instruments during operation of the pipeline system, which does not require the installation of additional diagnostic and / or measuring equipment, does not impose restrictions on the flow of fluid in the pipeline system, which does not require special tests that allow verification not only devices for measuring quantities, the sum of which can be measured using a summing device (flow rate, heat energy, etc.), but also other measuring instruments (pressure gauges, thermometers, etc.).

EFFECT: verification of a set of measuring instruments installed on a pipeline system during operation of the pipeline system (under stationary and non-stationary modes of fluid flow) without installing additional diagnostic and / or measuring equipment and without special preparation for testing.

This is achieved by the fact that, in contrast to the known technical solution, the inventive method takes into account the relationship of the entire totality of the measured values (operational parameters of the fluid flow): pressures, flows, temperatures, etc. Using (standard) measuring instruments installed at the facility - the pipeline system - they measure these quantities at time t (t∈Ω).

- результат измерения i-й величины в момент времени t(t∈Ω) - связан с истинным значением этой величины X_i,t соотношениемFurther, it is believed that

- the measurement result of the i-th value at time t (t∈Ω) is related to the true value of this quantity X _{i, t by the} ratio

where ε _i is the unchanged (or slowly changing) in time systematic measurement error of the i-th quantity, i∈I;

I is the set of all measuring instruments;

δε _{i, t} is the random component of the measurement error of the ith value at time t.

They write down the mathematical model of the pipeline system — relations that relate the true values of the measured quantities X _{i, t} for all instants of time t∈Ω, -

where f is a vector function;

μ is the vector of model coefficients characterizing the technical condition of the system equipment;

X is a vector composed of the quantities X _{i, t} , i∈I, t∈Ω.

An example of relation (2) for a pipeline system is a system of algebraic equations that relate the operational parameters of the fluid flow in a pipeline system under a stationary flow regime. For a pipeline system that does not contain power equipment (pumps, compressors), the components of the vector μ are coefficients characterizing the hydraulic resistance of the pipelines.

When specifying the components of the vector μ, expert knowledge is attracted, and the operating experience of the pipeline system is taken into account. For pipeline system objects whose technical state is unknown, the values of the components of the vector μ are assumed to be unknown. Given the features of the pipeline system, write down the relations connecting the components of the vector μ:

where g is a vector function.

An example of relation (3) is the equality of hydraulic resistance coefficients for sections of pipelines that have been in operation and continue to operate under the same conditions.

- дисперсию случайной составляющей ошибки измерения δε_i,t. Для тех измерительных приборов, для которых информация о дисперсии

отсутствует, значения

полагают неизвестными. Исходя из опыта эксплуатации трубопроводной системы записывают соотношения, связывающие значения

:Next, for all measuring instruments installed on the pipeline system and all time instants t∈Ω, the quantity

- the variance of the random component of the measurement error δε _{i, t} . For measuring instruments for which dispersion information

absent values

believed to be unknown. Based on the operating experience of the pipeline system, relations relating values are written

:

where h is a vector function;

.σ is the vector whose components are

.

, или равенство между собой всех дисперсий

, соответствующих одному измерительному прибору i и разным моментам времени

. Последнее предположение выполняется, если замеры режимных параметров потока флюида проводятся в течение не очень продолжительного периода времени и i-й измерительный прибор в течение этого времени не заменяли на другой.An example of relation (4) is the equality of all dispersions to a certain constant determined from the nameplate characteristics of the measuring device

, or the equality of all variances

corresponding to one measuring device i and different points in time

. The last assumption is fulfilled if the measurement of the operational parameters of the fluid flow is carried out over a not very long period of time and the i-th measuring device during this time was not replaced by another.

) суммы квадратов отклонений результатов измерений режимных параметров потока флюида с поправкой на систематические ошибки

от истинных значений этих величин X_i,t:The values of systematic errors ε _i are sought in accordance with the least squares method by minimizing the weighted (with weights

) the sum of the squared deviations of the measurement results of the operational parameters of the fluid flow, adjusted for systematic errors

from the true values of these quantities X _{i, t} :

Thus, a conditional optimization problem is obtained with the objective function (5) and constraints (2) - (4). In addition to the systematic errors ε _{i, the} sought quantities are the true values of the measured parameters X _{i, t} and the unknown components of the vectors μ and σ.

They solve the problem of conditional optimization with the objective function (5) and constraints (2) - (4), find systematic errors ε _i , (i∈I).

The solution is obtained using optimization packages (for example, MATLAB, Maple, Optimization, etc.) or using subject-oriented programs that take into account the specifics of the technological system under consideration.

Description of drawings

In FIG. 1 is a structural diagram illustrating the relationship of a group of measuring devices and a system for transmitting information to a computing device.

In FIG. 2-3 are graphs illustrating an example implementation of the method.

The implementation of the invention

At the objects of pipeline transport (Fig. 1), measuring devices 1 are installed, the data from which are transmitted to the computing device 2 via the telemetry system.

The following is an example of a specific application of the proposed method.

As an example of a pipeline system, a horizontal linear gas pipeline with an external diameter of 1220 mm is considered. There are 9 measuring points along the gas pipeline route from point No. 1 at the beginning to point No. 9 at the end of the pipeline. Measurement points divide the gas pipeline into 8 sections: section 1 - between measurement points No. 1 and No. 2, etc., section 8 - between measurement points No. 8 and No. 9. The lengths of sections 1, ..., 8 are respectively 26 km; 29.2 km; 27.8 km; 25.3 km; 14.3 km; 24.6 km; 17.3 km; 12.4 km. At each measurement point, pressure and temperature are measured, and at the last measurement point (measurement point No. 9), gas flow is also measured.

в пунктах замеров № I (i=1, 2,…, 9).In FIG. 2 shows graphs of pressure measurements

in measuring points No. I (i = 1, 2, ..., 9).

The gas pipeline under consideration has a large diameter and is operated at high gas flow rates, therefore, the changes in the accumulating capacity of the pipes are small compared to the pumping volumes and a stationary gas flow model can be used to find systematic measurement errors. The relationship between the parameters in a stationary gas flow mode along a horizontal linear gas pipeline — in accordance with the industry standard STO Gazprom 2-3.5 - 051 - 2006. The norms for the technological design of main gas pipelines is described by the equation

where P ⁱⁿ is the pressure at the beginning of the pipeline, MPa;

P ^out - pressure at the end of the pipeline, MPa;

c ₀ = 9.0553⋅10 ¹⁰ ;

Δ is the relative density of the gas through the air;

λ is the coefficient of hydraulic resistance;

z _aver is the average over the length of the gas pipeline value of the gas compressibility coefficient;

T _aver is the average temperature of the transported gas, along the length of the pipeline, K;

L is the length of the gas pipeline, km;

q - gas consumption, mln. m ³ / day;

E - hydraulic efficiency coefficient characterizing the technical condition of the gas pipeline;

D is the internal diameter of the gas pipeline, mm.

,

, Δ_j, z_aver,j, T_aver,j, L_j, λ_j, q_j, D_j, где индекс j (j=1, 2, …, 8) указывает на принадлежность параметров j-й секции.Relation (6) can be written for each of the eight sections of the pipeline in question. For this, in relation (6), P ⁱⁿ , P ^out , Δ, z _aver , T _aver , L, λ, q, D should be replaced by

,

, Δ _j , z _{aver, j} , T _{aver, j} , L _j , λ _j , q _j , D _j , where the index j (j = 1, 2, ..., 8) indicates that the parameters of the jth section belong to.

There are no associated gas withdrawals along the gas pipeline route; therefore, for all sections, q values are equal to:

The values of E for all sections are unknown, but, given the features of the pipeline system, they can be considered equal:

The values of the coefficient λ from section to section vary slightly, they can be considered the same for all sections λ _j = λ. The same holds for the compressibility coefficient z _{j, aver} = z _aver and average temperature T _{j, aver} = T _aver .

The diameters of all sections are equal (D ₁ = D ₂ = ... = D ₈ ), gas is transported through all sections with the same relative density of gas through the air (Δ ₁ = Δ ₂ = ... = Δ ₈ ).

Thus, from relation (6) it follows that the difference (P ⁱⁿ ) ² - (P ^out ) ² from section to section changes mainly due to a change in the length of section L. Thus, the larger the length of section L, the the larger the value should be (P ⁱⁿ ) ² - (P ^out ) ² , which means that the greater the “distance” between adjacent curves in FIG. 2. Referring to FIG. 2 shows that this condition is not fulfilled. For example, the “distance” between curves 8 and 9 is significantly greater than the “distances” between other pairs of curves, despite the fact that the length of this section is minimal - 12.9 km.

The reason for this inconsistency of measurements to physical laws is the presence of systematic errors in pressure measurements. For the presence of systematic errors, we test pressure gauges located at measuring points No. 1, No. 2, No. 3, No. 4, No. 5, No. 8, No. 9.

и температуры

в пунктах замеров №1-9 и замеры расхода

в пункте замеров №9.To verify these pressure gauges, we will use measurements of the operating parameters of the fluid flow, carried out by standard measuring instruments, i.e. pressure measurements

and temperature

in measurement points No. 1-9 and flow measurements

at measurement point No. 9.

The measurement frequency is 5 minutes, the total observation period is 5 days. According to the claimed method, we denote the set of times t when measurements are taken, through Ω.

We assume that the results of measurements of quantities are related to their true values by relation (1). It should be noted that temperature measurements at measuring points No. 1-9, pressure measurements at measuring points 6 and 7, flow measurements at measuring point 9 do not contain systematic errors, therefore, relation (1) should be rewritten as

where P _{i, t} and T _{i, t} are the true values of pressure and temperature, respectively, in the measurement point No. i at time t;

q _t is the true value of the flow at time t;

ε _i is the systematic error of pressure measurement at measurement point No. i;

,

и

- случайные составляющие ошибок измерения давления, температуры в пункте замеров № i и расхода в пункте замеров №9 соответственно в момент времени t.

,

and

- random components of errors in measuring pressure, temperature at measurement point No. i and flow rate at measurement point No. 9, respectively, at time t.

Next, we write and solve the problem of conditional optimization.

First, we formulate the constraint system of the conditional optimization problem - we write down the mathematical model of the pipeline system (we specify equation (2)) and the relations connecting the components of the vectors μ and σ (we specify equations (3) and (4), respectively).

As a mathematical model of the pipeline system, we use the stationary gas flow model: for each section of the pipeline and each time moment t∈Ω, we write relation (6), we supplement the resulting system of equations with relation (7) and Shukhov’s formula from the industry standard STO Gazprom 2 - 3.5 - 051 - 2006. Norms of technological design of gas pipelines ”for calculating T _aver .

The components of the vector μ are the hydraulic efficiency coefficients of the gas sections E ₁ , E ₂ , ..., E ₈ . The values of E ₁ , E ₂ , ..., E _{8 are} unknown and are related by relation (8).

Information on the variances of the random components of the measurement errors — the values of the components of the vector σ — is also absent. Taking into account the fact that all measuring instruments during the observation period - 5 days - were not replaced by others, and the same measuring instruments were installed in the measurement points for measuring pressure and temperature, then for any time t ₁ ∈Ω and t ₂ ∈Ω (t ₁ ≠ t ₂ ) we consider the equalities

,for manometers

,

.for thermometers

.

The superscript P (T) refers to the variance of the random components of the measurement errors of pressure gauges (thermometers).

Next, we write down the objective function of the conditional optimization problem. According to the least squares method, we obtain

We solve the problem of conditional optimization in variables

и q_t, $${\sigma }_t^q$$

,

and q _t $${\sigma }_t^q$$

,

E _j (j = 1, 2, ..., 8).

As a result of the solution, we find the values of systematic errors

ε ₁ = -0.1032 MPa, ε ₂ = -0.0171 MPa, ε ₃ = -0.0439 MPa,

ε ₄ = 0.0427 MPa, ε ₅ = -0.0291 MPa, ε ₈ = 0.0329 MPa, ε ₉ = -0.3334 MPa.

.In FIG. Figure 3 shows the graphs of pressure measurements at measurement points No. 1-9, adjusted for systematic errors, i.e. quantities

.

на величину систематических ошибок ε_i позволяет получить не противоречащую физическим законам совокупность графиков изменения давления по газопроводу.Graphs (Fig. 3) show that the correction measurements

by the amount of systematic errors ε _i allows you to get a set of graphs of pressure changes in the pipeline that does not contradict physical laws.

Claims (1)

A method for verifying a group of measuring instruments at a production facility for observing a process, including measuring the operational parameters of the fluid flow of a technological process with measuring instruments installed on a piping system, the values of systematic errors being sought in accordance with the least squares method by minimizing the weighted sum of squares of the deviations of the measured mode fluid flow parameters corrected for systematic errors from the true values of et x values such that the ratio describing the mathematical model of the pipeline system, as well as the relations between the coefficients of the model describing the technical condition of the equipment system, and relations between the variance components of random measurement errors.

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