RU2638129C2 - Method for diagnosing power transformers - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: method for diagnosing power transformers comprises an oil sample preparation unit, a chromatographic analysis module, a chromatograph, a chromatography data transmission unit, a digital data processing unit, a common bus, a data entry unit, a memory unit, a diagnostic results unit. It additionally comprises a transformer, a partial discharge module, a data acquisition unit, a partial discharge calibration unit, a partial discharge filtration unit, a unit of data transmission by partial discharge method, a chemical-physical analysis module, an oil sample preparation unit, an oil dielectric strength determination unit, an oil purity determination unit, an oil flash temperature measurement unit, an analytical unit, a database of reference data. The oil sample preparation unit, the chromatograph and the chromatography data transmission unit are combined into the chromatographic analysis module, and the module of diagnostics by partial discharge method consists of a data collection unit, a partial discharge calibration unit, a partial discharge filtration unit, a unit of data transmission by partial discharge method. The chemical-physical analysis module consists of an oil sample preparation unit, an oil dielectric strength determination unit, an oil purity determination unit, an oil flash temperature measurement unit.

EFFECT: increased accuracy of determining the power transformer state.

2 dwg, 1 tbl

Description

A method for diagnosing power transformers is intended to determine the state of an oil-filled power transformer and to take further measures depending on its condition.

The invention relates to methods for diagnosing high-voltage equipment and can be used in enterprises operating such equipment.

The issue of determining the status of transformer equipment is extremely relevant, because more than half of the equipment fleet have served their operational life, and in accordance with the regulations require major repairs. A correct assessment of the possibility of further operation of the equipment on the basis of the diagnostics performed allows avoiding unjustified financial costs, as well as losses associated with an emergency power outage.

At the moment, there are a variety of methods for diagnosing power transformers.

For example, in the "Method for the diagnosis of power three-winding transformers" (RF patent No. 2446406), the diagnosis is carried out by recording phase and line voltages in various load conditions. By solving systems of equations, based on the obtained values, the state of the transformer is determined.

Similarly, in the "Method for diagnosing power transformers" (RF patent No. 2237254), the magnitudes and phase angles of the voltages and currents of all transformer windings are measured in two different transformer operating modes, and, by performing the following mathematical calculations, they solve the state equations of the power transformer based on the nodal conductivity matrix and nodal resistances and determine the various parameters of the transformer winding.

In the "Method for diagnosing the state of solid insulation of power transformers" (application No. 93027023), the condition of the transformer is judged by the degree of decomposition of the solid insulation, and by the content of thermal decomposition products in the oil.

The “Transformer Diagnostic Method” (RF patent No. 21117955) includes vibrational impact on the transformer, during which the main parameters are measured, analyzing which they make an assessment of the design's compliance with operational requirements.

The “Diagnostic system for oil-filled measuring transformers” (RF patent for utility model No. 82867) intended for the diagnosis of oil-filled high-voltage equipment based on the results of chromatographic analysis of gases dissolved in oil was selected as a prototype. After taking an oil sample, the system forms a vector of measured concentrations of gases dissolved in oil, the coordinates of which are the concentrations of these seven gases dissolved in transformer oil. Then, a vector of boundary permissible values is constructed and an analysis is carried out for the vector exceeding the measured concentrations of the selected vector of boundary concentrations.

However, judging the state of an expensive and time-consuming installation and repair of a power transformer by only one method is insufficient, which leads to significant operational costs in the case of incorrect conclusions, because sometimes the accuracy of tests is influenced, for example, even by errors in the selection of oil.

This invention is directed to the joint application of essentially different techniques in order to improve the accuracy of determining the status of a power transformer.

The technical result of the invention consists in increasing the reliability of the diagnosis of transformers, predicting its performance and determining the duration of the next test. The proposed diagnostic method allows you to more reliably detect the presence of a developing defect in the transformer and determine its type.

The problem is achieved in that the method for diagnosing power transformers, including an oil sample preparation unit, a chromatographic analysis module, a chromatograph, a chromatography data transmission unit, a digital data processing unit, a common bus, a data input unit, a memory unit, a diagnostic result unit, according to the invention, is additionally contains a transformer, a partial discharge module, a data collection unit, a partial discharge calibration unit, a partial discharge filtering unit, a partial discharge method data transmission unit c, a chemical-physical analysis module, an oil sample preparation unit, an oil dielectric strength determination unit, an oil purity determination unit, an oil flash temperature measuring unit, an analytical unit, a reference information database, an oil sample preparation unit, a chromatograph and a transmission unit chromatography data are combined into a chromatographic analysis module, and the partial discharge diagnostic module consists of a data collection unit, a partial discharge calibration unit, a partial discharge filtering unit poisons, a partial discharge method data transmission unit, a chemical-physical analysis module consists of an oil sample preparation unit, an oil dielectric strength determination unit, an oil purity determination unit, an oil flash temperature measuring unit, and the transformer is connected by one-way connections to the partial discharge module, module chromatographic analysis, a module of chemical-physical analysis, a partial discharge module by one-way communication is connected to a digital data processing unit, a chromatographic module is one-way analysis is connected to a digital data processing unit, one-way digital data processing unit is connected to a common bus, one-way common bus is connected to a memory unit, one-way chemical-physical analysis module is connected to data input unit, one-way communication data input unit is connected to a memory unit, a memory unit with a one-way communication connected to the analytical unit, an analytical unit with a one-way communication connected to a diagnostic results unit, an analytical unit two-way it is connected by a connection to a database of reference information.

This problem was solved by partially automating the analysis and processing of diagnostic data in order to present it in a form convenient for conducting analytical work to determine the status of the power transformer.

The structure of the utility model is shown in FIG. 1, FIG. 2 and consists of the following modules and blocks:

1. The transformer.

2. The module of partial discharges (PD).

2.1. Data collection unit.

2.2. CR calibration block.

2.3. Filtration block of the Czech Republic.

2.4. Block of data transmission of the Czech Republic.

3. Chromatographic analysis module.

3.1. Oil sample preparation unit.

3.2. Chromatographer.

3.3. Chromatography data transfer unit.

4. Module for chemical-physical analysis of oil.

4.1. Oil sample preparation unit.

4.2. Block for determining the dielectric strength of oil.

4.3. Block for determining the oil purity class.

4.4. Oil flash temperature measuring unit.

5. Digital processing unit.

6. Common bus.

7. The data input unit.

8. The memory block.

9. The analytical unit.

10. Block diagnostic results.

11. Database of reference information (DB NSI).

Data input unit (7), memory unit (8), analytical unit (9), diagnostic results unit (10) are part of the specialized PC software as an automated workstation (AWP) of a specialist.

Transformer (1) - diagnostic object, oil-filled power transformer.

ChP module (2) - is intended for diagnostics of the Transformer (1) by the method of partial discharges.

Data acquisition unit (2.1) - designed to collect test data.

PD calibration block (2.2) - designed to obtain the true value of the charge level.

PP filtering unit (2.3) - the functions of this unit are filtering the signal according to three parameters: by the time of arrival of the pulse, by amplitude and by polarity of the pulse.

PD data transmission unit (2.4.) - is responsible for the transmission of diagnostic results to the system using the PD method.

The chromatographic analysis module (3) is designed to detect damage and defects in the structural components of electrical equipment.

The oil sample preparation unit (3.1) is responsible for the correct procedure for sampling the oil in accordance with the recommendations for working with the device.

Chromatographer (3.2) is a device that is used for chromatographic separation and analysis of mixtures of substances.

The chromatograph includes:

- a system for introducing a test mixture of substances (samples);

- chromatographic column;

- detecting device (detector);

- registration and temperature control systems.

Chromatography data transfer unit (3.3.) - is responsible for transmitting diagnostic results to the system.

The chemical-physical analysis module (4) is intended for laboratory determination of the following oil properties - dielectric strength, flash point, and also for the content of mechanical impurities.

Oil sample preparation unit (4.1) - is responsible for the correct procedure for sampling the oil in accordance with the standard.

In the Block for determining the dielectric strength of oil (4.2), the insulating properties of transformer oil are studied.

In the Block for determining the oil purity class (4.3), the content of mechanical impurities in the transformer oil is determined as a result of the destruction of paints, insulation.

Oil flash point (4.4). The results of the unit are characterized by the degree of purity of the oil, which makes it possible to assess the presence of potentially dangerous volatile impurities in it.

The digital data processing unit (5) converts the analog signals of Modules (2) and (3) into a digital computer format. This block has a place, because many more enterprises use well-proven instruments with analog signal processing.

The common bus (6) is a common cable through which data is transferred from Modules (2) and (3) to the Memory Block (8).

The data input unit (7) is used to manually enter the diagnostic data of the Transformer (1) by the method of chemical-physical analysis of oil (Module (4)), as well as other additional information necessary for conducting analytical work.

The memory block (8) is the place of collection and temporary storage of diagnostic results.

The analytical unit (9) is the central unit of the analytical system for the diagnosis of the transformer. It compares the results obtained with regulatory data, with the results of previous diagnostic studies, makes a decision on the general condition of the Transformer (1) and its individual nodes, and makes a health forecast.

Block of diagnostic results (10) - diagnostic data is prepared in a convenient way for analysis, both graphical and paper.

Database of NSI (11) - a corporate database of regulatory and reference information of the enterprise with data on each equipment with a history of operation, diagnostics and repair.

The transformer is diagnosed in three consecutive stages.

By the method of partial discharges (Module 2), it is possible to measure not only the level of partial discharges in the transformer winding, but also to determine their location. The measurement of the characteristics of partial discharges is carried out in order to determine the absence of insulation of the transformer under test during testing with normalized voltage of partial discharges, the intensity of which exceeds the value established by the standard or technical specifications for the transformer.

Tests are carried out as follows. The transformer is disconnected from the network and from the load. Capacitive sensors of the device for recording and analyzing signals of partial discharges in isolation are mounted on the lower part of the transformer input. In Block (2.1), calibration is performed by injecting a signal pulse alternately at each input of the transformer and simultaneously fixing the signal from each input in the data acquisition unit. Then, the operating voltage is supplied to the input of the transformer, and capacitive sensors record the actual level of discharges. The obtained values of the discharges fall into the filtering unit, where the signal is filtered from interference according to three parameters: by the time of arrival of the pulse, by amplitude, and by the polarity of the pulse. Then, after digital processing in Block (5) through the Common Bus (6) and Memory Block (8), the data goes to the Analytical block (9), where they are analyzed for the danger of a defect in the transformer winding, namely, the type of defect and its degree are determined hazard depending on the image (the image obtained when registering partial discharges) of the received signals on the phase-frequency distribution, determining the amplitude of the signals, constructing the frequency spectrum and analyzing the trend of the defect.

Chromatographic analysis (Module 3) of gases dissolved in oil is a special method used to detect damage and defects in the structural components of electrical equipment and allows:

- track the development of processes in equipment;

- identify defects at an early stage of their development, not detected by traditional methods;

- determine the alleged nature of the defect and the degree of damage;

- navigate when determining the location of damage.

The condition of the equipment is evaluated by comparing the quantitative data obtained in the analysis with the boundary values of the gas concentration and the rate of increase in the concentration of gases in oil. It is important to distinguish between normal and excessive volumes of gas. Normal aging or gas generation varies depending on the design of the transformer, the load and the type of insulation material.

The sampling device of the syringe type (V = 10-100 ml) of the required oil volume and preparation take place in the Oil sample preparation unit (3.1). The prepared oil is placed in a Chromatograph (3.2), which, using the method of separation of mixtures of substances or particles, based on the difference in the speeds of their movement along the column in a system of immiscible and moving relative to each other phases, determines the ratio of the concentrations of characteristic gases: C ₂ H ₂ / C ₂ N ₄ , CH ₄ / H ₂ , C ₂ H ₄ / H ₂ H ₆ . The predicted defect is determined based on the relationship of these values listed in the table.

Based on this table, a defect is determined. The obtained analog value is converted to digital and entered in the memory unit (8) for further analysis.

It should be noted that the chromatographic analysis of gases dissolved in oil practically does not inform about the quality and condition of the oil itself.

In the Module (4), a laboratory study of transformer oil is carried out according to the following properties - dielectric strength, flash point, determination of purity class.

In all oil-filled electrical appliances, oil is used as the main dielectric to increase electrical strength.

The sampler takes the syringe type (V = 10-100 ml) of the required volume of oil and the preparation takes place in the oil sample preparation unit. Oil samples taken are measured in the Block for determining the dielectric strength of oil (4.2), Block for determining the class of oil purity (4.3), as well as in the Block for determining the flash point of oil (4.4).

The dielectric strength test of the oil is carried out as follows: two electrodes are placed in a measuring container with selected oil. The capacity is installed in the measuring device. A voltage is applied to the electrodes at those limits at which a breakdown of the oil is possible. The voltmeter is turned on on the low voltage side, and is graduated taking into account the transformation coefficient of the test transformer, i.e. shows test voltage. The test is carried out 5-6 times with an interval of 1-10 minutes. For breakdown voltage, the average of six (n = 6) values is taken and its value is fixed.

Upr = (U1 + U2 + ... + Un) / n.

In the Block for determining the oil purity class (4.2), the content of mechanical impurities in the transformer oil is determined and is made in order to identify contaminants and impurities that have entered the oil as a result of the destruction of paints and insulation. A light beam is passed through an oil sample and by measuring light fluxes scattered by particles of mechanical impurities (sizes 2-200 μm), the class of oil purity is determined in accordance with GOST 17216-2001. The concentration and dispersed composition of particles of mechanical impurities is also determined.

The oil taken in the Sample preparation unit (4.1) in the Oil flash point determination unit (4.4) is poured into a closed vessel (crucible) and heated. The emitted oil vapors, mixed with air, form a mixture that flares up at a certain temperature when a flame is brought to it or from an electric spark. When oil decomposes, accompanied by a decrease in flash point, gases are released. In this case, gas protection is triggered (for signal or shutdown). The resulting flash temperature is fixed.

The obtained values of the studies of Module (4) are entered in the Data Input Unit (7) and stored for the duration of the diagnosis in the Memory Unit (8).

In the Analytical unit (9), the analysis of the received data from all three modules is carried out for compliance with the working state of the transformer, and if they coincide, a conclusion is made about the working state of the transformer, the next diagnostic date is scheduled, or a decision on repair is made.

This invention with a high degree of certainty allows us to state the operability of the transformer. At the same time, while not being costly for the enterprise, this method of diagnostics helps to avoid unplanned expenses for expensive and time-consuming equipment repairs due to insufficient information about its condition.

Claims (1)

A method for diagnosing power transformers, including an oil sample preparation unit, a chromatographic analysis module, a chromatograph, a chromatography data transmission unit, a digital data processing unit, a common bus, a data input unit, a memory unit, a diagnostic results unit, characterized in that it further comprises a transformer, a module partial discharges, data acquisition unit, partial discharges calibration unit, partial discharges filtering unit, partial discharges data transmission unit, chemical-physical analysis module, block the preparation of the oil sample, the unit for determining the dielectric strength of the oil, the unit for determining the purity of the oil, the unit for measuring the flash point of the oil, the analytical unit, the database of normative and reference information, the unit for preparing the oil sample, the chromatograph, and the chromatography data transmission unit are combined into a chromatographic analysis module, and partial discharge diagnostic module consists of a data collection unit, a partial discharge calibration unit, a partial discharge filtering unit, a partial method data transmission unit discharges, the chemical-physical analysis module consists of an oil sample preparation unit, an oil dielectric strength determination unit, an oil purity determination unit, an oil flash temperature measuring unit, the transformer being connected by one-way connections to a partial discharge module, a chromatographic analysis module, and a chemical- physical analysis, the partial discharge module by one-way communication is connected to the digital data processing unit, the chromatographic analysis module by one-way communication is connected to the bl with a digital data processing interface, the digital data processing unit is connected by a one-way connection to a common bus, the common bus is connected by a one-way connection to a memory unit, the chemical-physical analysis module is connected by a one-way connection to a data input unit, the data input unit by a one-way communication is connected to a memory unit, a memory unit one-way communication connected to the analytical unit, one-way analytical unit connected to the diagnostic results unit, two-way analytical unit connected to the standard database ive reference information.

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