阅读说明：本技术 一种油浸式变压器的油温控制方法及使用该方法的变压器 (Oil temperature control method of oil-immersed transformer and transformer using same ) 是由 陈欢 郭伟强 刘利权 李有明 于 2019-04-19 设计创作，主要内容包括：本发明提供了一种油浸式变压器的油温控制方法及使用该方法的变压器,所述控制方法通过获取上一年度当日的变压器油温变化历史曲线,对温度变化历史曲线进行求导,得到温度变化大的时刻点,再对温度变化大的时刻点进行修正,以获得变压器顶层油温的目标控制温度；然后根据变压器顶层油温的目标控制温度,控制变压器降温设备的运行,即控制变压器的冷却风机和/或压缩机的运行,利用冷媒介质和蒸发器对变压器进行降温处理,对变压器的油温精确控制,使变压器在稳定的状态下工作,效率大大提高,变压器的使用寿命也得到了提升。(The invention provides an oil temperature control method of an oil-immersed transformer and a transformer using the method, wherein the control method obtains a history curve of the change of the oil temperature of the transformer on the same day in the last year, conducts the history curve of the change of the temperature to obtain a time point with large temperature change, and then corrects the time point with large temperature change to obtain a target control temperature of the top oil temperature of the transformer; and then controlling the operation of transformer cooling equipment, namely controlling the operation of a cooling fan and/or a compressor of the transformer according to the target control temperature of the top oil temperature of the transformer, performing cooling treatment on the transformer by using a refrigerant medium and an evaporator, and accurately controlling the oil temperature of the transformer, so that the transformer works in a stable state, the efficiency is greatly improved, and the service life of the transformer is also prolonged.)

1. A method for controlling the top oil temperature of a transformer of an oil-immersed transformer is characterized by comprising the following steps:

s1, acquiring a change history curve of the top oil temperature of the transformer on the same day in the previous year;

s2, carrying out derivation processing on the change history curve of the top layer oil temperature to obtain a time point with larger temperature change;

s3, correcting the temperature of the time point with larger temperature change to obtain the target control temperature of the top oil temperature of the transformer;

and S4, controlling the operation of the cooling equipment of the oil-immersed transformer according to different control intervals where the target control temperature is located.

2. The transformer top oil temperature control method according to claim 1, further comprising the step of S4:

s41: preferably, when the target control temperature T is less than or equal to 30 ℃, the cooling fan is closed, the compressor stops running, and the temperature is automatically reduced by using the oil cooling circulation of the transformer;

s42: preferably, when the target control temperature T is more than 30 ℃ and less than or equal to 55 ℃, a cooling fan of the transformer is started, and the rotating speed of the cooling fan is controlled;

s43: preferably, when the target control temperature T is more than 55 ℃ and less than or equal to 70 ℃, the cooling fan stops running and the compressor is used for refrigerating;

s44: preferably, when the target control temperature T is more than 70 ℃ and less than or equal to 85 ℃, the fan and the compressor are started simultaneously, the rotating speed of the cooling fan is increased to the highest rotating speed, the operating frequency of the compressor is increased to the maximum operating frequency, and the transformer oil is cooled.

3. The transformer top layer oil temperature control method according to claim 2, wherein the S42 further comprises the steps of:

s421: when the target control temperature is more than 30 ℃ and less than or equal to 40 ℃, the rotating speed of the cooling fan runs at a constant speed of a first rotating speed omega 1;

s422: when the target control temperature is more than 40 ℃ and less than or equal to 55 ℃, the cooling fan operates at a second rotating speed omega 2, wherein omega 2 is omega 1+2.2e^(T-30)/7。

4. The transformer top layer oil temperature control method according to claim 2, wherein the S43 includes the steps of:

s431: determining a target frequency F1 of the compressor according to the target control temperature, and controlling the compressor to perform refrigeration operation for a first preset time t1 according to the target frequency F1;

s432: detecting a variation value delta T1 of the top oil temperature of the transformer before and after T1, and if the variation value delta T1 is larger than a first preset temperature value, executing a step S433;

s433: controlling the operation frequency of the compressor to increase to a first preset frequency F2, and continuously operating for a second preset time t2, wherein the first preset frequency F2 is F1 +. DELTA.F;

s434: and detecting a change value delta T2 of the top oil temperature of the transformer before and after T2, and if the change value delta T2 is smaller than a second temperature preset value, returning to the step S431, and controlling the operation frequency of the compressor to be maintained at the frequency F1 for operation.

5. The method for controlling top-level oil temperature of a transformer according to claim 1, wherein in S1, the variation history curve of the top-level oil temperature of the transformer is obtained by: and measuring the numerical value of the top oil temperature of the transformer changing along with the time on the day of the previous year, establishing a mapping table for the measured value, and fitting to obtain a temperature change curve T g (T) on the day of the previous year.

6. The method for controlling the top-layer oil temperature of the transformer according to claim 1, wherein in step S2, the method for obtaining the time point with the larger temperature variation comprises: the curve T is derived from g (T) to obtain a set of time points with derivative values greater than 2.

7. The transformer top layer oil temperature control method according to claim 1, wherein in S3, the following formula is adopted for temperature correction:

formula 1): t1 ═ Ti-0.12 × Ts;

equation 2): t2 ═ Ti +0.08 × Ts;

equation 3): t3 ═ Ti-0.1 × Ts;

wherein Ti is the top-layer oil temperature of the transformer on the same day of the previous year corresponding to the moment point with larger temperature change;

when the outdoor temperature Ts temperature range is: ts is more than or equal to 40 ℃ and less than or equal to 0 ℃, and the corrected target control temperature T1 is corrected and calculated by adopting a formula 1;

when the outdoor temperature Ts temperature range is: ts is more than or equal to 0 ℃ and less than or equal to 25 ℃, and the corrected target control temperature T2 is corrected and calculated by adopting a formula 2;

when the outdoor temperature Ts temperature range is: ts is more than or equal to 25 ℃ and less than or equal to 45 ℃, and the corrected target control temperature T3 is corrected and calculated by adopting a formula 3.

8. The transformer top layer oil temperature control method according to claim 7, wherein the temperature correction formula further comprises a second correction: and the target control temperature T4 after the second correction is T1+ delta T, or T4 is T2+ delta T, or T4 is T3+ delta T, when the transformer is in a power utilization peak period, the delta T is a positive value, and when the power utilization is in a stationary period, the delta T is a negative value.

9. The transformer top layer oil temperature control method according to claim 1, wherein the S4 further comprises the steps of:

s5, detecting the top oil temperature of the transformer in real time, and when the temperature is abnormal for multiple times within a third preset time t3, entering an alert area by the transformer and executing the step S6;

and S6, calculating the maximum hot point temperature value of the transformer winding according to the environment temperature, the equivalent load current and the duration, and judging whether the transformer is cut off from the power grid.

10. A transformer, characterized in that it employs the transformer top layer oil temperature control method of any one of claims 1-9.

Technical Field

The invention relates to the field of transformers, in particular to an oil temperature control method of an oil-immersed transformer and a transformer using the same.

Background

At present, the transformer is an important and indispensable power device in a power transmission grid and plays a vital role in regulating the voltage of the grid. Power transformers suffer from core and winding losses during use, which leads to increased core and winding temperatures. In order to ensure safe and reliable operation of the transformer, the winding temperature, the core temperature and the transformer oil temperature of the transformer need to be limited within a safe range, so the transformer needs to be cooled. Most of transformers running on the existing power grid are still oil-immersed transformers, the oil cooling of internal transformer oil is carried out by common oil-immersed transformers through radiating fins arranged around the transformers, but the radiating fins are greatly influenced by the environment and often cannot achieve the expected effect when the ambient temperature is high, so that the transformers have large faults, for example, the insulation performance of the transformer oil is reduced, coils are aged and even the transformers are subjected to fire, explosion and other accidents due to overhigh oil temperature.

The temperature rise standard of the transformer in China is subject to the ambient temperature of 40 ℃, so the top oil temperature of the transformer generally cannot exceed 40 ℃ plus 55 ℃ to 95 ℃. The temperature of the top oil exceeds 95 deg.C, and the temperature of the inner coil exceeds the heat-resisting strength of the coil insulator, so that the insulation will not age too fast, and the monitoring of the temperature of the top oil of the transformer should be controlled below 85 deg.C. In the range of 80-140 ℃, the service life loss of the paper insulation of the transformer is doubled every 6 ℃ rise of the temperature. This rule is commonly referred to as the six degree rule. When the cooling equipment is out of order, the cooling condition is destroyed, the running temperature of the transformer rises rapidly, and the life loss of the transformer insulation is increased rapidly. As described in the literature, the insulating material can be used for 20 years when the temperature is kept at 95 ℃; the temperature is 105 ℃, the service life is about 7 years, and the temperature is 120 ℃ for about 2 years; the temperature is 170 ℃ for about 10-12 days.

In order to reduce waste, improve the electric energy quality, improve the working efficiency and the service life of the transformer, reduce the temperature of transformer cooling oil and improve the transformer oil cooling technology, the technology becomes a preferred technology for breaking through various bottlenecks.

Disclosure of Invention

The invention aims to provide a transformer oil temperature control method and a transformer using the method, which are used for cooling through a cooling fan and a compressor, accurately controlling the oil temperature of the transformer together and ensuring that the transformer works and operates in a proper temperature range.

In order to achieve the purpose, the technical scheme of the invention is realized as follows:

a method for controlling the top oil temperature of a transformer of an oil-immersed transformer comprises the following steps:

s1, acquiring a change history curve of the top oil temperature of the transformer on the same day in the previous year;

s2, carrying out derivation processing on the change history curve of the top layer oil temperature to obtain a time point with larger temperature change;

s3, correcting the temperature of the time point with larger temperature change to obtain the target control temperature of the top oil temperature of the transformer;

and S4, controlling the operation of the cooling equipment of the oil-immersed transformer according to different control intervals where the target control temperature is located.

Further, the step S4 includes the following steps:

s41: when the target control temperature T is less than or equal to 30 ℃, the cooling fan is closed, the compressor stops running, and the temperature is automatically reduced by using the oil cooling circulation of the transformer;

s42: when the target control temperature T is more than 30 ℃ and less than or equal to 55 ℃, starting a cooling fan of the transformer and simultaneously controlling the rotating speed of the cooling fan;

s43: when the target control temperature T is more than 55 ℃ and less than or equal to 70 ℃, the cooling fan stops running and the compressor is used for refrigerating;

s44: and when the target control temperature T is more than 70 ℃ and less than or equal to 85 ℃, simultaneously starting the fan and the compressor, increasing the rotating speed of the cooling fan to the highest rotating speed, increasing the operating frequency of the compressor to the maximum operating frequency, and cooling the transformer oil.

Further, the S42 further includes the following steps:

s421: when the target control temperature is more than 30 ℃ and less than or equal to 40 ℃, the rotating speed of the cooling fan runs at a constant speed of a first rotating speed omega 1;

s422: when the target control temperature is more than 40 ℃ and less than or equal to 55 ℃, the cooling fan operates at a second rotating speed omega 2, wherein omega 2 is omega 1+2.2e^(T-30)/7。

Further, the S43 includes the following steps:

s431: determining a target frequency F1 of the compressor according to the target control temperature, and controlling the compressor to perform refrigeration operation for a first preset time t1 according to the target frequency F1;

s432: detecting a variation value delta T1 of the top oil temperature of the transformer before and after T1, and if the variation value delta T1 is larger than a first preset temperature value, executing a step S433;

s433: controlling the operation frequency of the compressor to increase to a first preset frequency F2, and continuously operating for a second preset time t2, wherein the first preset frequency F2 is F1 +. DELTA.F;

s434: and detecting a change value delta T2 of the top oil temperature of the transformer before and after T2, and if the change value delta T2 is smaller than a second temperature preset value, returning to the step S431, and controlling the operation frequency of the compressor to be maintained at the frequency F1 for operation.

Further, in S1, the obtaining method of the change history curve of the top-layer oil temperature of the transformer includes: and measuring the numerical value of the top oil temperature of the transformer changing along with the time on the day of the previous year, establishing a mapping table for the measured value, and fitting to obtain a temperature change curve T g (T) on the day of the previous year.

Further, in S3, the following formula is used for the temperature correction:

formula 1): t1 ═ Ti-0.12 × Ts;

equation 2): t2 ═ Ti +0.08 × Ts;

equation 3): t3 ═ Ti-0.1 × Ts;

wherein Ti is the top-layer oil temperature of the transformer on the same day of the previous year corresponding to the moment point with larger temperature change;

when the outdoor temperature Ts temperature range is: ts is more than or equal to 40 ℃ and less than or equal to 0 ℃, and the corrected target control temperature T1 is corrected and calculated by adopting a formula 1;

when the outdoor temperature Ts temperature range is: ts is more than or equal to 0 ℃ and less than or equal to 25 ℃, and the corrected target control temperature T2 is corrected and calculated by adopting a formula 2;

when the outdoor temperature Ts temperature range is: ts is more than or equal to 25 ℃ and less than or equal to 45 ℃, and the corrected target control temperature T3 is corrected and calculated by adopting a formula 3.

Further, the temperature correction formula further comprises a second correction: and the target control temperature T4 after the second correction is T1+ delta T, or T4 is T2+ delta T, and T4 is T3+ delta T, wherein when the transformer is in a power utilization peak period, the delta T is a positive value, and when the power utilization is in a stationary period, the delta T is a negative value.

Further, the S4 further includes the following steps:

s5, detecting the top oil temperature of the transformer in real time, and when the temperature is abnormal for multiple times within a third preset time t3, entering an alert area by the transformer and executing the step S6;

and S6, calculating the maximum hot point temperature value of the transformer winding according to the environment temperature, the equivalent load current and the duration, and judging whether the transformer is cut off from the power grid.

The invention also provides a transformer, and the transformer adopts the transformer top layer oil temperature control method.

Compared with the prior art, the method for controlling the top oil temperature of the transformer has the following advantages:

1, a natural oil circulating cooling structure of a traditional oil-immersed transformer is changed, the control precision of the oil temperature of the transformer is improved, the heat dissipation cooling efficiency of the transformer can be improved, the service life of the transformer can be prolonged, and accidents are reduced;

2, the compressor and the cooling fan in the transformer are adjusted in different modes, the control modes are flexible and various, the oil temperature of the transformer can be accurately controlled according to the target control temperature, the cooling effect is good, and the method is suitable for various complex occasions and environments; the energy waste and noise pollution caused by the fact that the rotating speed of the cooling fan keeps a high-speed rotating state in the prior art are avoided.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate an embodiment of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:

fig. 1 is a schematic flow chart of a method for controlling an oil temperature of a transformer according to the present invention;

FIG. 2 is a schematic flow chart of the present invention for controlling the cooling fan and the compressor;

fig. 3 is a schematic control flow diagram of the compressor of the present invention.

Detailed Description

It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.

Reference will now be made in detail to the exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, like numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the present invention.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in this specification and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should also be understood that the term "and or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items.

It is to be understood that although the terms first, second, third, etc. may be used herein to describe various information, these information should not be limited to these terms. These terms are only used to distinguish one type of information from another. For example, first information may also be referred to as second information, and similarly, second information may also be referred to as first information, without departing from the scope of the present invention. The word "if" as used herein may be interpreted as "at … …" or "when … …" or "in response to a determination", depending on the context.

The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.