RU2803700C2 - Method for determining transformer leakage reactances individually - Google Patents

Abstract

FIELD: measuring technology.

SUBSTANCE: invention can be used to determine the leakage reactance of a transformer. The active resistance of the primary winding r₁ is measured_. When idling, the supply voltage U ₀₁, current value I ₀₁ in the primary winding are measured. Voltage U ₀₂ on the secondary winding is determined, reduced to the primary winding. The complex resistance of the primary winding is determined using formula z ₁ = (U ₀₁ - U ₀₂)/I ₀₁ and reactive resistance is determined using formula x ₁ = ±√(z₁ ²-r₁ ²). A reverse open-circuit experiment is carried out and the complex resistance of the secondary winding, reduced to the primary winding, is determined using formula z ₂ = (² U ₀₂ ^’ - ² U ₀₁)/I ₀₂ ^’ where ² U ₀₂ ^’ is the voltage on the secondary winding reduced to the primary winding, ² U ₀₁ is the voltage on the primary winding, I ₀₂ ^’ is the current in the secondary winding reduced to the primary winding.
EFFECT: making it possible to experimentally determine leakage reactance for each winding separately; leakage reactance of the secondary winding reduced to the primary winding is determined.

1 cl, 1 dwg, 1 ex

Description

Field of technology to which the invention relates

The invention relates to electromechanics, namely to transformers.

State of the art

The closest to the invention in technical essence is a method for determining the leakage reactance of a transformer separately, which consists in determining the values of voltages on the windings of the transformer and the currents in them (see RU 2685571).

The disadvantage of this known method is the impossibility of determining the negative leakage reactance of one of the windings.

The total leakage reactance for a transformer with concentric cylindrical windings is

where ω is the cyclic frequency of the current, μ ₀ is the magnetic constant, D is the average diameter of the winding, w is the number of turns (given), is the height of the winding, and ₀ is the gap between the coils, and ₁ , and ₂ are the thickness of the coils.

The flux linkage of the external winding is equal to

where i is the reduced current, aw ₁ =w ₂ =w (indices are shown for clarity of integration). Hence the leakage reactance of the external winding is equal to

Subtracting it from (1) gives the leakage reactance of the internal winding

Thus, the leakage reactance of one of the windings may be negative and the known method is not always reliable.

Disclosure of the Invention

The problem to be solved by the claimed invention is to increase the reliability of determining the leakage reactance for each winding separately.

The technical result consists in making it possible to experimentally determine the leakage reactance for each winding separately.

The technical result is ensured by the following set of features:

A method for determining the leakage reactance of a transformer separately, consisting in determining the values of voltages on the windings of the transformer and the currents in them, characterized in that the active resistance of the primary winding r ₁ is measured, and the value of the supply voltage is measured at idle the magnitude of the current in the primary winding and determine the voltage on the secondary winding reduced to the primary winding, in this case, the complex resistance of the primary winding is determined by the formula and reactive - according to the formula carry out a reverse open-circuit experiment and determine the complex resistance of the secondary winding, reduced to the primary winding, using the formula Where - voltage on the secondary winding reduced to the primary winding, - voltage on the primary winding, - the current in the secondary winding, reduced to the primary winding, and determine the leakage reactance of the secondary winding, reduced to the primary winding.

The problem to be solved by the claimed invention and the technical result are interrelated as follows.

Providing the possibility of experimentally determining the leakage reactance for each winding separately leads to an increase in the reliability of their determination.

The drawing shows the electrical equivalent circuit of the transformer at idle.

Carrying out the invention

The invention can be implemented as follows.

With the method of determining the leakage reactance of a transformer separately, which consists in determining the values of voltages on the windings of the transformer and the currents in them, measuring the active resistance of the primary winding r ₁ , and at idle, measuring the value of the supply voltage the magnitude of the current in the primary winding and determine the voltage on the secondary winding reduced to the primary winding, in this case, the complex resistance of the primary winding is determined by the formula and reactive - according to the formula carry out a reverse open-circuit experiment and determine the complex resistance of the secondary winding, reduced to the primary winding, using the formula Where - voltage on the secondary winding reduced to the primary winding, - voltage on the primary winding, - the current in the secondary winding, reduced to the primary winding, and determine the leakage reactance of the secondary winding, reduced to the primary winding.

Thus, the purpose of the invention - its use as a method for determining the leakage reactance of a transformer separately - is being realized.

Information confirming the possibility of obtaining a technical result when implementing the invention (the cause-and-effect relationship of essential features with the specified technical result) is as follows.

Measurement of the active resistance of the primary winding r ₁ , at idle, measurement of the supply voltage current magnitude in the primary winding and determining the voltage on the secondary winding reduced to the primary winding, determination of the complex resistance of the primary winding using the formula and reactive - according to the formula conducting a reverse no-load experiment and determining the complex resistance of the secondary winding reduced to the primary winding using the formula Where - voltage on the secondary winding reduced to the primary winding, - voltage on the primary winding, - the current in the secondary winding, reduced to the primary winding, and the determination of the leakage reactance of the secondary winding, reduced to the primary winding, makes it possible to experimentally determine the leakage reactance for each winding separately.

Consequently, the totality of essential features is sufficient to achieve the technical result provided by the invention.

Description of the method and the complex of devices and instruments for its implementation. High-precision idling method. From the equivalent circuit of the transformer at idle (Fig. 1) it follows that the reduced voltage on the secondary winding is equal to

It follows that

From the reversibility of the transformer it follows

Here and below, the upper left index “2” indicates that the value was obtained in the second (reversible) experiment.

Method for experimental (high-precision) determination of transformer parameters (XX)

1. Measure and “add” quantities:

2. In accordance with (2), z ₁ is determined.

3. Determine x ₁ , C ₁ .

4. In accordance with (3) determine

5. Define

Example 1. Determine both leakage resistances for the OSM-1.00 transformer. Measured values with high precision:

Existing measuring systems make it possible to measure the effective values of electrical quantities and phase shifts between them with almost any given accuracy. However, when measuring quantities one by one, the high accuracy of each measurement is of little benefit, since the measured quantities themselves are not stable.

Since for the purpose of determining reactance, it is not so much the magnitudes of currents and voltages that are important, but rather the relationships between them, the problem with their instability is solved by simultaneous registration of the necessary parameters by the processor. This ensures the accuracy of the calculated values, comparable to the accuracy of a single measurement.

Thus, the proposed method, in contrast to the prototype, provides increased reliability in determining the leakage reactance for each winding separately.

The effectiveness of the proposed method is determined by its accuracy.

Claims (1)

A method for determining the leakage reactance of a transformer separately, consisting in determining the values of voltages on the windings of the transformer and the currents in them, characterized in that they measure the active resistance of the primary winding r ₁ at no-load, measure the value of the supply voltage the magnitude of the current in the primary winding and determine the voltage on the secondary winding reduced to the primary winding, in this case, the complex resistance of the primary winding is determined by the formula and reactive - according to the formula carry out a reverse open-circuit experiment and determine the complex resistance of the secondary winding, reduced to the primary winding, using the formula Where - voltage on the secondary winding reduced to the primary winding, - voltage on the primary winding, - the current in the secondary winding, reduced to the primary winding, and determine the leakage reactance of the secondary winding, reduced to the primary winding.

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