ES2314737T3 - PROCEDURE FOR REGULATION OF REFRIGERATION IN A FORCE TRANSFORMER. - Google Patents

Abstract

The invention relates to a method for controlling devices for cooling an oil-filled power transformer with one or more cooling stages during which only the respective type of cooling of the transformer and the type of coolant for each existing cooling stage have to be input and by comparing with all non-volatile stored technically possible and meaningful combination possibilities, the corresponding characteristic quantities are determined for calculating the oil temperature or winding temperature.

Description

Procedure for the regulation of cooling in a force transformer.

The invention relates to a process for regulation of provisions for the cooling of a oil-filled force transformer, depending on your oil or winding temperature.

The oil-filled force transformers they are characterized internationally, according to their constructive type and its cooling mode, with a 4 letter code. Both first letters refer in this context to the modality of the transformer cooling itself; for this there are the abbreviations, known to an expert in the specialty, ON for "Oil Natural" [with natural oil], OF for "Oil Forced "[with forced oil], OP for" Oil Forced ", but with an oil cooling system with a pump axial, or OD for "Oil Directed" [with directed oil] as well as GF for "Gas Forced" [with forced gas] (for transformers with cooling by SF_ {6}) as a special construction type. The two other letters arranged behind designate the respective type of cooling medium; for this there is AN for "Air Natural" [with natural air], AF for "Air Forced", [with forced air], WF for "Water Forced" [with forced water].

Through a combination of different cooling modes of transformers, as well as  different types of cooling medium exist, for consequently, the most different constructive forms of transformers, which can be represented by coding explained.

In addition, a force transformer full of oil has as a rule several stages of cooling, of those that can be presented as the basis for the different cooling modalities and respectively the different types of the cooling medium.

For the regulation of the provisions of cooling in a force transformer, such as pumps or fans, which act on the individual stages of the refrigeration, it is known to determine or respectively calculate the respective temperature of the insulating oil or the respective winding temperature, and compare it with a limit value preset in advance for each cooling stage, realizing that when exceeded it is put into operation the respective cooling arrangement; for so long until the value is transferred back to lower values limit of the respective stage. The calculations of the values explained and exposed snapshots of oil temperature insulating or winding temperature, are common for an expert in the specialty, they are described in detail in IEC 354 "Loading guide for oilimmersed power transformers "[load guide for transformers force immersed in oil], pages 25 and following, in particular pages 33 and following. Depending on the type of the transformer and of the respective cooling stage, in this IEC standard (of the International Electrotechnical Commission) the most established different variables and the most different parameters as well as in Total different calculation requirements.

From the patent application document from the USA 2002/0161558 A1 an apparatus is known and implicitly  a corresponding procedure for the regulation of provisions intended for cooling a transformer of oil-filled force, which has at least one stage of refrigeration, depending on your oil temperature or windings In this case, the oil temperature or respectively of the windings is determined according to the calculation requirements of the aforementioned IEC standard and. how basis for the commissioning of the cooling stages, it compare with a respective corresponding limit value. In the cases of this known apparatus and the corresponding procedure, must be carefully selected from the IEC standard first for the first time, separately for each stage of refrigeration, the respective variables, which correspond to the type of the transformer in combination with the respective mode of the cooling and must be introduced in a corresponding unit of regulation, so that a correct calculation of the temperature of the oil and respectively of the windings, and then a comparison with a limit value dependent on the cooling stage

Such data entry is complicated for the Username. On the one hand, it is painful to deduce the parameters individual correctly from the IEC standard (Often, IEC standard is not available precisely to the user, and frequently the manipulative staff is not used to the treatment With the extensive publication. On the other hand, errors may appear when choosing the respective parameter and the respective formulas from the set of rules and when making its manual transfer to a corresponding unit of regulation.

This is where the invention is applied. It's mission of the invention indicate a procedure that saves the user the Performing these expensive activities.

The problem posed by this mission is resolves through a procedure with the characteristics of the Claim of this patent. In the case of this procedure it is only necessary to identify the constructive type and the cooling modes of the respective transformer of force and indicate the characterization encoded by letters, which explained at the beginning of the respective modality of the transformer and medium type cooling cooling in their respective cooling stages. These few data necessary for the force transformer are known to the user, they are contained on the board feature identification and can be moved with ease, in a simple way and without transfer errors to a corresponding regulation unit.

The process according to the invention takes advantage of the fact that the calculation requirements to be applied to calculate the specific temperatures of the oil as well as the windings, including the respective variables and parameters, are unequivocally established in the said IEC standard and therefore must be used by the user. These values, therefore, are already stored in a non-volatile manner by the manufacturer, so practically only one parameter has to be entered manually: The 4-letter coding for each existing cooling stage of the corresponding force transformer
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Only in the case of a modification of the IEC standard, when parameters and parameters should be modified calculation requirements that are established, a Modification of stored values in a non-volatile manner. Since such modifications of relevant criteria in standards binding, however, are expected only rarely, in Any case after several years, you can accept the expense for such internal subsequent setting of the parameters.

To perform the procedure is suitable, for example, the electronic regulation device TAPCON®  260 offered by the applicant.

The invention should be explained below. still in greater detail by way of example, with the help of some drawings.

In them:

Figure 1 shows the procedure according to invention in a schematic representation of all stages of the consecutive procedure

Figure 2 shows an enlarged representation of important stages of the procedure as well as the choice of the parameters in the case of the process according to the invention.

First, with the help of Figure 1, Describe the entire procedure.

At one time it is carried out by the manufacturer in the respective regulator or respectively in the electronic regulating device, in which the procedure, a non-volatile storage of all 4-letter encodings that are possible, and of the variables and specific calculation requirements associated with the IEC standard explained.

In addition, first the non-volatile storage of limit values \ theta_ {1} ... \ theta_ {n} for the oil temperature or respectively of the windings, for each of the stages of cooling 1 ... n existing in the corresponding force transformer

After this has been done, you can Begin the actual procedure. First, it enter separately in the 4-letter code of the respective mode of transformer cooling and type of cooling medium for each cooling stage 1 ... n present.

Then it is done in the unit calculator, from the pairs of values, stored in a non-volatile way, of all possible 4-letter encodings possible, reading the calculation requirements, of the variables and constants, relevant according to the IEC, for the values entered for the respective calculation of the oil temperature? or respectively windings

With these values, the true calculation of the current value of the temperature? oil and respectively windings.

This calculation is made in accordance with the specific requirements of IEC 354, which are relevant for the respective transformer. For this calculation the upper oil layer temperature temperature), the load current, the load factor - that is, the ratio between the load current and the current of sizing- and other specific parameters that are planned in the IEC standard.

A comparison of the calculated temperature? of the oil and respectively of the windings, with the limit value \ theta_ {1} ... \ theta_ {n} for each cooling stage 1 ... n separately. For this comparison limit values are used \ theta_ {1} ... \ theta_ {n} stored in a way not volatile.

With the formulation "comparison by separate "means that it is first checked whether the value of calculado calculated exceeds the limit value the1 for the first stage of cooling. If this is the case, the first stage of cooling is activated. Also I know Check if the value of \ calculated is so large that he, in addition to this, it also exceeds the limit value \ theta_ {2} of The second stage of refrigeration. In such a case, it is activated also the second stage of refrigeration. This comparison is continues in a similar way for other possible stages of additional cooling

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Additionally, it is convenient, in the case of exceeding the limit value \ {n} for the last (highest) cooling stage n existing, additionally also the triggering of an alarm; and eventually also lead to the shutdown of the transformer.

The most important stages of the procedure are they must explain then still once again with the help of the Figure 2. The regulation apparatus, used for the realization of the procedure in this example, you have four contacts of switching S1 ... S4; he is usable for a transformer that It has up to four different cooling stages 1 ... 4. Yes, in in the case of the respective transformer, fewer stages are present of cooling, the remaining remaining contacts remain unused.

The upper part of Figure 2 shows how, from the respective mode of refrigeration (is say the first two capital letters) and of the corresponding type of the cooling medium (ie the next two letters uppercase) the 4-letter encoding of the one already set is set she has talked.

The cooling stage 0, that is the normal operation, usually always receives the denomination ONAN

Cooling stages with the same cooling mode are increasingly designated with an index that begins with the figure 1. Characteristic parameters are associated with each cooling stage, the gradient gr , the exponent of the windings and , and the time constant of tau windings, which depend on the type of the transformer and the mode of cooling, and consequently on the respective 4-letter coding.

In the center of Figure 2 the matrix is shown of all possible 4-letter encodings and of the associated explained parameters, as stored in a way not volatile

From this matrix the respective ones are read relevant parameters, which are set specifically for individual cooling stages from the introduction of the type of transformer and the mode of cooling. With these parameters are then performed the temperature calculation current? of the oil and respectively of the windings

In the lower part of Figure 2 is shown non-volatile storage of limit values \ theta_ {1} ... \ theta_ {n} for each cooling stage 1 .... n -Here expressed as a percentage switching point in degrees Celsius through the corresponding temperature calculated the of the windings.

With these values stored in a way not volatile, the described comparison of the temperature the calculated with the respective limit value \ theta_ {1} ... \ theta_ {n} for each cooling stage 1 ... n separately. In the example shown here, the Transformer really has four stages of cooling 1 ... 4, so that all contacts S1 ... S4 are busy here existing in the regulation apparatus.

Additionally, in this example they are planned also two other switching contacts 5.6, realizing that the switching contact 5, when the limit value is exceeded \ theta_ {4} for the last cooling stage 4, triggers an alarm signal, which signals that the regular stages of refrigeration are not manifestly refrigerated back to a lower temperature to the force transformer heated (excessively). A cause of this can be found eg in a damaged pump.

An additional switching contact 6 is triggered when it is still manifestly exceeded the limit value for this alarm notice; then it stops all the transformer, in order to avoid damage.

In the example shown, the stages of cooling 1 ... 3 are structured in the construction type ONAF, as explained above, and therefore are completed by an index 1 ... 3. The last stage of cooling 4 is in this example of the OPAF type.

In principle, in the case of the procedure according to the invention they can be used as comparative quantities both the calculated oil temperature as well as the calculated winding temperature, so here generally both types of the calculated temperature are provided of the same reference sign. They are established however differences in response sensitivity, since the temperature of the windings is modified essentially faster than the oil temperature, which Follow this with a certain inertia.

Claims (1)

1. Procedure for the regulation of provisions intended for cooling a transformer of oil-filled force, which has at least one stage of cooling (1 ... n) depending on its temperature? oil or windings, the temperature being determined the of the oil or respectively of the windings of according to the requirements of the IEC standard, and being compared this one with a corresponding limit value, because as a result of the comparison generate information for the commissioning of the at least a cooling stage, because the respective cooling stage (1 ... n) is put into service when its respective is exceeded limit value \ theta_ {1} .... \ theta_ {n} and because it gives rise to an alarm signal, to a error message or the trip of a protective switch, in the case that the current temperature? of the oil and respectively of windings also exceeds a limit value for last stage of cooling (n), characterized in that the respective mode of transformer cooling and the type of cooling medium for each of the existing cooling stages (1 .... n) are entered separately in a 4-letter coding, because the respective 4-letter coding, in each case entered, it is compared with a table, stored of beforehand in a non-volatile way, of all 4 encodings technically possible letters and of the variables and prescriptions of Specific calculations associated according to the IEC, because the prescriptions of calculation, variables and constants for the calculation of the temperature? of the oil and respectively of the windings, which in each case is relevant for 4-letter encodings that have been introduced and because each calculated temperature? of the oil and respectively of the windings are compared in each case with a limit value \ theta_ {1} ... \ theta_ {n} stored in a way not volatile, for the temperature of the oil or respectively of the windings for each existing cooling stage.