CN112487343A - Method for calculating working efficiency of cooling system of split oil-immersed transformer - Google Patents

Abstract

The invention provides a method for calculating the working efficiency of a cooling system of a split oil-immersed transformer, relates to the technical field of research on the cooling system of the split oil-immersed transformer, solves the problem that the calculated working efficiency value is inaccurate because the influence of the temperature and flow change of oil flow on the factory rated heat dissipation power of the cooling system when the transformer operates is not considered in the prior art, calculates the heating power of the split oil-immersed transformer and the rated heat dissipation power of the cooling system of the split oil-immersed transformer based on real-time operation parameters of the split oil-immersed transformer and the like, and the rated heat dissipation power is converted into the actual rated heat dissipation power, the influence of the temperature and flow change of oil flow in the normal operating environment on the factory rated heat dissipation power of the cooler is considered, the working efficiency of the cooling system is finally solved, the reliability of the calculation result is ensured, and the control force of workers on the operating state of the transformer is enhanced.

Description

Method for calculating working efficiency of cooling system of split oil-immersed transformer

Technical Field

The invention relates to the technical field of research on a split type oil immersed transformer cooling system, in particular to a method for calculating the working efficiency of the split type oil immersed transformer cooling system.

Background

In the running process of the transformer, factors such as system dirt accumulation, aging, defects, faults and the like can cause the working efficiency of a cooling system to be gradually reduced, and further the running state of the transformer is influenced, the working efficiency influence mechanism of the cooling system is complex, and accurate calculation is difficult to carry out, so that the dirt accumulation condition of a transformer substation cannot be accurately judged, inconvenience is brought to cleaning and maintenance of the transformer substation, the working efficiency of the cooling system is difficult to obtain only according to the state change of the transformer, and the reason of the abnormal running of the transformer cannot be accurately analyzed, therefore, a calculation method for the working efficiency of the cooling system of the transformer needs to be researched.

At present, related researches on a transformer cooling system in China are few, and the related researches are mostly limited to the calculation of the working efficiency of an integrated oil-immersed transformer cooling system, compared with an integrated heat dissipation mode of an oil-immersed transformer, the structure of the split oil-immersed transformer cooling system is changed, at the moment, the calculation method of the working efficiency of the integrated oil-immersed transformer cooling system is difficult to follow, in the calculation method of the working efficiency of the integrated oil-immersed transformer cooling system, the rated heat dissipation power of the cooling system adopts a performance factory test data calculation value, and the influence of the oil flow temperature and the flow change on the factory rated heat dissipation power of the cooling system when the transformer operates is not considered, so that a certain deviation exists between the rated heat dissipation power and a normal operation value, the calculation result is inaccurate, and the control of a worker on the operation state of; on the aspect that the research technical field is relatively closer to some aspects, chinese patent publication No. CN107133739A, 9/15/2017 discloses a method for calculating efficiency of a split cooling system of a transformer, which performs multidimensional assessment on operation, adaptability, effect, initial capability and the like of the split cooling system of the transformer, and establishes an efficiency calculation index system suitable for the split cooling system of the transformer.

Disclosure of Invention

In order to solve the problem that the calculated working efficiency value is inaccurate due to the fact that the influence of oil flow temperature and flow change on the factory rated heat dissipation power of a cooling system when a transformer operates is not considered in the conventional method for calculating the working efficiency of the cooling system of the oil-immersed transformer, the invention provides a method for calculating the working efficiency of the cooling system of the split oil-immersed transformer, which improves the reliability of a calculation result and enhances the control force of working personnel on the operation state of the transformer.

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

a method for calculating the working efficiency of a cooling system of a split oil-immersed transformer at least comprises the following steps:

s1, collecting real-time operation data and nameplate parameters of a split oil immersed transformer;

s2, collecting performance delivery test data and actual operation parameters of the split oil immersed transformer cooling system;

s3, calculating the heating power P of the split oil-immersed transformer based on the real-time operation data and nameplate parameters of the split oil-immersed transformer_z；

S4, determining rated heat dissipation power P of the cooling system of the split oil-immersed transformer based on performance factory test data of the cooling system of the split oil-immersed transformer_le；

S5, combining transformation according to actual operation parameters of the cooling system of the split oil immersed transformerThe influence of the temperature and flow change of the oil flow on the factory rated heat dissipation power of the cooling system during the operation of the device is to set the rated heat dissipation power P_leConversion to actual rated heat dissipation Power P'_le；

S6, obtaining the actual heat dissipation power P of the transformer oil tank based on the results of the infrared temperature measurement radiation and convection calculation of the split oil immersed transformer_sa；

S7, combining actual heat dissipation power P of transformer oil tank_saCalculating the actual heat dissipation power P of the cooling system of the split oil-immersed transformer based on the energy conservation principle_la；

S8, according to actual rated heat dissipation power P'_leAnd the actual heat dissipation power P of the cooling system of the split oil immersed transformer_laAnd solving the working efficiency of the split oil immersed transformer cooling system.

Preferably, the real-time operation data and nameplate parameters of the split oil-immersed transformer include: the method comprises the following steps of no-load loss of the split oil-immersed transformer, rated load loss of the split oil-immersed transformer, load value of the split oil-immersed transformer, actual current of the low-voltage side of the split oil-immersed transformer, rated current of the low-voltage side of the split oil-immersed transformer, actual current of the high-voltage side of the split oil-immersed transformer and rated current of the high-voltage side of the split oil-immersed transformer.

Preferably, the heating power P of the split oil-immersed transformer in step S3_zSatisfies the formula:

wherein, P_zRepresenting the heating power of the split oil-immersed transformer; p₀Representing the no-load loss of the split oil-immersed transformer; p_eRepresenting rated load loss of the split oil-immersed transformer; i is_LaRepresenting the actual current of the low-voltage side of the split oil immersed transformer; i is_LeRepresenting the rated current of the low-voltage side of the split oil-immersed transformer; i is_HaRepresenting the actual current of the high-voltage side of the split oil immersed transformer; i is_HeAnd the rated current of the high-voltage side of the split oil-immersed transformer is shown.

Preferably, the rated heat dissipation power P of the cooling system of the split oil-immersed transformer in step S4_leSatisfies the following conditions:

P_le＝P₁-P₂

wherein, P₁The method comprises the steps of (1) representing the heating power of an electric heater in performance delivery test data of a split oil-immersed transformer cooling system; p₂And the heat loss of the testing device in the performance factory test data of the split oil-immersed transformer cooling system is shown.

Preferably, the rated heat dissipation power P is set in step S5_leConversion to actual rated heat dissipation Power P'_leThe formula of (1) is:

wherein, P'_leRepresenting the actual rated heat dissipation power of the cooling system of the split oil-immersed transformer; t is_i'-T_o' represents the actual inlet and outlet oil temperature difference of the cooling system of the split oil-immersed transformer; q_aRepresenting the actual average oil flow of the cooling system of the split oil-immersed transformer; q_eRepresenting rated average oil flow of a cooling system of the split oil-immersed transformer; k represents a correction coefficient;

actual average oil flow Q of split oil-immersed transformer cooling system_aThe solving formula of (2) is as follows:

wherein, T_i、T_o、T_tThe oil temperatures Q and the oil temperatures Q in an oil inlet, an oil outlet and an oil conveying pipe of a cooling system of the split oil immersed transformer in actual operation are respectively_tIs the actual oil flow rate in the oil line.

Rated average oil flow Q of cooling system of split oil-immersed transformer_eThe solving formula of (2) is as follows:

wherein, c_iThe specific heat capacity of the transformer oil at the oil inlet of the split type oil immersed transformer cooling system is shown; c. C_oThe specific heat capacity of the transformer oil at the oil outlet of the split type oil immersed transformer cooling system is shown; rho_iThe density of transformer oil at an oil inlet of the split type oil immersed transformer cooling system is represented; rho_oThe density of the transformer oil at the oil outlet of the split type oil-immersed transformer cooling system is shown; p_leThe rated heat dissipation power of the cooling system of the split oil-immersed transformer is represented; t is_i-T_oAnd the temperature difference of the inlet oil and the outlet oil of the cooling system in the performance factory test data of the split oil-immersed transformer cooling system is shown. Herein, when determining the rated heat dissipation power of the cooling system of the split oil-immersed transformer, considering the influence of the temperature and flow change of oil flow in the normal operation environment on the factory rated heat dissipation power of the cooling system, the rated heat dissipation power P is obtained_leConversion to actual rated heat dissipation Power P'_leThe accuracy of working efficiency calculation of the split oil immersed transformer cooling system is improved.

Preferably, in step S6, the actual heat dissipation power P of the oil tank of the split oil-immersed transformer_saThe satisfied calculation formula is:

P_sa＝P_r+P_c

wherein, P_rRepresenting the radiation heat dissipation power of the split oil-immersed transformer oil tank; p_cAnd the convection heat dissipation power of the split oil-immersed transformer oil tank is shown.

Preferably, the radiation heat dissipation power P of the split type transformer oil tank_rThrough calculation of a network method, the wall surfaces of a room where the split oil-immersed transformer oil tank and the split oil-immersed transformer oil tank are located form a multi-surface system to form a model of a split oil-immersed transformer tank body, four side surfaces of the split oil-immersed transformer oil tank are respectively a first surface, a second surface, a third surface and a fourth surface, the top surface of the split oil-immersed transformer oil tank is a fifth surface, and the wall surface of the room where the split oil-immersed transformer oil tank is located is a wall surfaceThe surface is a sixth surface, the temperature distribution condition of each surface of the split oil-immersed transformer oil tank is determined by utilizing infrared temperature measurement, the total radiant quantity emitted by each surface of the split oil-immersed transformer oil tank in unit area is obtained by combining with kirchhoff law, the net radiant heat exchange quantity between each surface of the split oil-immersed transformer oil tank and the wall surface of a room in unit time is finally confirmed, and the formula of the net radiant heat exchange quantity between each surface of the split oil-immersed transformer oil tank and the wall surface of the room in unit time is as follows:

Φ_Σ＝Φ_1,6+Φ_2,6+Φ_3,6+Φ_4,6+Φ_5,6

＝A₁X_1,6(J₁-J₆)+A₂X_2,6(J₂-J₆)+...+A₅X_5,6(J₅-J₆)

wherein phi is_ΣThe net radiation heat exchange quantity between each surface of the split oil-immersed transformer oil tank and the wall surface of a room in unit time is represented; phi is a_1,6Representing the net amount of radiant heat exchange between the first surface and the sixth surface; phi is a_2,6Representing the net amount of radiant heat exchange between the second surface and the sixth surface; phi is a_3,6Representing the net amount of radiant heat exchange between the third surface and the sixth surface; phi is a_4,6Representing the net amount of radiant heat exchange between the fourth surface and the sixth surface; phi is a_5,6Net radiant heat exchange between the fifth surface and the sixth surface; a. the₁Representing the area of the first surface; a. the₂Representing the area of the second surface; a. the₅Represents the area of the fifth surface; j. the design is a square_pRepresenting the total radiant energy emitted per unit area, X, on the p-th surface_p1，pDenotes the p th₁Angle coefficient of surface to pth surface, p₁And p is 1,2,3,4,5,6, and p1 is not equal to p.

The bottom surface radiation heat exchange quantity of the split oil-immersed transformer is not counted, the rest five surfaces of the split oil-immersed transformer oil tank and the wall surface of the room where the split oil-immersed transformer oil tank is located form a multi-surface system, a model of a split oil-immersed transformer box body is formed, calculation of radiation heat dissipation power of the split oil-immersed transformer oil tank is refined, after temperature distribution of each surface of the split oil-immersed transformer oil tank is determined, the radiation heat dissipation power of the split oil-immersed transformer oil tank is further calculated, errors caused by the fact that the radiation heat dissipation power of the split oil-immersed transformer oil tank is calculated only by the average temperature of the split oil-immersed transformer oil tank are avoided, calculation accuracy of the working efficiency of a follow-up split oil-immersed transformer cooling system is further guaranteed, and further control over the operation state.

Preferably, the convection heat dissipation power P of the transformer oil tank_cCalculated by the convective heat transfer principle.

Preferably, the actual heat dissipation power P of the split oil-immersed transformer cooling system in step S7_laThe calculation formula of (2) is as follows:

P_la＝P_z-P_sa

wherein, P_laRepresenting the actual heat dissipation power of the cooling system of the split oil-immersed transformer; p_zRepresenting the heating power of the split oil-immersed transformer; p_saAnd the actual heat dissipation power of the split oil-immersed transformer oil tank is represented.

Preferably, in step S8, the formula for solving the working efficiency of the split oil-immersed transformer cooling system is as follows:

η＝P_la/P′_le×100％

and eta represents the working efficiency of the cooling system of the split oil-immersed transformer.

Compared with the prior art, the technical scheme of the invention has the beneficial effects that:

the invention provides a method for calculating the working efficiency of a cooling system of a split oil-immersed transformer, which is characterized by calculating the heating power of the split oil-immersed transformer and the rated heat dissipation power of the cooling system of the split oil-immersed transformer based on the real-time operation data and nameplate parameters of the split oil-immersed transformer, the performance factory test data and the actual operation parameters of the cooling system of the split oil-immersed transformer, converting the rated heat dissipation power into the actual rated heat dissipation power, considering the influence of the temperature and the flow change of oil flow in the normal operation environment on the factory rated heat dissipation power of a cooler, finally solving the working efficiency of the cooling system of the split oil-immersed transformer according to the actual rated heat dissipation power and the actual heat dissipation power of the cooling system of the split oil-immersed transformer, wherein the whole process is based on the calculation of the real-time operation state of the split oil, the reliability of the calculation result is ensured, and the control force of the working personnel on the running state of the transformer is enhanced.

Drawings

Fig. 1 is a flowchart illustrating a method for calculating the working efficiency of a cooling system of a split oil-immersed transformer according to an embodiment of the present invention;

fig. 2 is a structural diagram of a split oil-immersed transformer and a polyhedral system formed by wall surfaces of a room in which the split oil-immersed transformer is located in the embodiment of the present invention.

Detailed Description

The drawings are for illustrative purposes only and are not to be construed as limiting the patent;

for better illustration of the present embodiment, certain parts of the drawings may be omitted, enlarged or reduced, and do not represent actual dimensions;

it will be understood by those skilled in the art that certain well-known descriptions of the figures may be omitted.

The technical solution of the present invention is further described below with reference to the accompanying drawings and examples.

Example 1

Fig. 1 is a flowchart of a method for calculating the operating efficiency of a cooling system of a split oil-immersed transformer, where the method includes the following steps:

s1, collecting real-time operation data and nameplate parameters of a split oil immersed transformer; the real-time operation data and nameplate parameters of the split oil immersed transformer comprise: the method comprises the following steps of (1) no-load loss of a split oil-immersed transformer, rated load loss of the split oil-immersed transformer, a load value of the split oil-immersed transformer, actual current of a low-voltage side of the split oil-immersed transformer, rated current of the low-voltage side of the split oil-immersed transformer, actual current of a high-voltage side of the split oil-immersed transformer and rated current of the high-voltage side of the split oil-immersed transformer;

s2, collecting performance delivery test data and actual operation parameters of the split oil immersed transformer cooling system;

s3, calculating the heating power P of the split oil-immersed transformer based on the real-time operation data and nameplate parameters of the split oil-immersed transformer_z；

S4, determining rated heat dissipation power P of the cooling system of the split oil-immersed transformer based on performance factory test data of the cooling system of the split oil-immersed transformer_le；

S5, according to actual operation parameters of the split oil immersed transformer cooling system, and in combination with influences of oil flow temperature and flow change on delivery rated heat dissipation power of the cooling system during transformer operation, rated heat dissipation power P is obtained_leConversion to actual rated heat dissipation Power P'_le；

S6, obtaining the actual heat dissipation power P of the transformer oil tank based on the results of the infrared temperature measurement radiation and convection calculation of the split oil immersed transformer_sa；

S7, combining actual heat dissipation power P of transformer oil tank_saCalculating the actual heat dissipation power P of the cooling system of the split oil-immersed transformer based on the energy conservation principle_la；

S8, according to actual rated heat dissipation power P'_leAnd the actual heat dissipation power P of the cooling system of the split oil immersed transformer_laAnd solving the working efficiency of the split oil immersed transformer cooling system.

In this embodiment, the heating power P of the split oil-immersed transformer in step S3_zSatisfies the formula:

wherein, P_zRepresenting the heating power of the split oil-immersed transformer; p₀Representing the no-load loss of the split oil-immersed transformer; p_eRepresenting rated load loss of the split oil-immersed transformer; i is_LaRepresenting the actual current of the low-voltage side of the split oil immersed transformer; i is_LeRepresenting the rated current of the low-voltage side of the split oil-immersed transformer; i is_HaRepresenting the actual current of the high-voltage side of the split oil immersed transformer; i is_HeAnd the rated current of the high-voltage side of the split oil-immersed transformer is shown.

In this embodiment, the rated heat dissipation power P of the cooling system of the split oil-immersed transformer in step S4_leSatisfies the following conditions:

P_le＝P₁-P₂

wherein, P₁The method comprises the steps of (1) representing the heating power of an electric heater in performance delivery test data of a split oil-immersed transformer cooling system; p₂And the heat loss of the testing device in the performance factory test data of the split oil-immersed transformer cooling system is shown.

In the present embodiment, the rated heat dissipation power P is obtained in step S5_leConversion to actual rated heat dissipation Power P'_leThe formula of (1) is:

wherein, P'_leRepresenting the actual rated heat dissipation power of the cooling system of the split oil-immersed transformer; t is_i'-T_o' represents the actual inlet and outlet oil temperature difference of the cooling system of the split oil-immersed transformer; q_aRepresenting the actual average oil flow of the cooling system of the split oil-immersed transformer; q_eRepresenting rated average oil flow of a cooling system of the split oil-immersed transformer; k represents a correction coefficient;

actual average oil flow Q of split oil-immersed transformer cooling system_aThe solving formula of (2) is as follows:

wherein, T_i、T_o、T_tThe oil temperatures Q and the oil temperatures Q in an oil inlet, an oil outlet and an oil conveying pipe of a cooling system of the split oil immersed transformer in actual operation are respectively_tIs the actual oil flow rate in the oil line.

Rated average oil flow Q of cooling system of split oil-immersed transformer_eIs solved forThe formula is as follows:

wherein, c_iThe specific heat capacity of the transformer oil at the oil inlet of the split type oil immersed transformer cooling system is shown; c. C_oThe specific heat capacity of the transformer oil at the oil outlet of the split type oil immersed transformer cooling system is shown; rho_iThe density of transformer oil at an oil inlet of the split type oil immersed transformer cooling system is represented; rho_oThe density of the transformer oil at the oil outlet of the split type oil-immersed transformer cooling system is shown; p_leThe rated heat dissipation power of the cooling system of the split oil-immersed transformer is represented; t is_i-T_oAnd the temperature difference of the inlet oil and the outlet oil of the cooling system in the performance factory test data of the split oil-immersed transformer cooling system is shown.

In this embodiment, in step S6, the actual heat dissipation power P of the split oil-immersed transformer oil tank_saThe satisfied calculation formula is:

P_sa＝P_r+P_c

wherein, P_rRepresenting the radiation heat dissipation power of the split oil-immersed transformer oil tank; p_cAnd the convection heat dissipation power of the split oil-immersed transformer oil tank is shown.

In the embodiment, the radiation heat dissipation power P of the split type transformer oil tank_rThrough calculation by a network method, as shown in fig. 2, wherein 1 represents a split oil-immersed transformer oil tank, 2 represents a room where the split oil-immersed transformer oil tank is located, wall surfaces of the split oil-immersed transformer oil tank 1 and the room 2 where the split oil-immersed transformer oil tank is located form a multi-surface system to form a model of the split oil-immersed transformer oil tank, and four side surfaces of the split oil-immersed transformer oil tank are respectively a first surface a₁A second surface A₂And a third surface A₃And a fourth surface A₄The top surface of the split oil-immersed transformer oil tank is a fifth surface A₅The wall surface of the room 2 where the split oil-immersed transformer oil tank is located is a sixth surface A₆By using infrared temperature measurement, the score is determinedThe temperature distribution condition of each surface of the split oil-immersed transformer oil tank is combined with kirchhoff law to obtain the total radiant emittance emitted by each surface of the split oil-immersed transformer oil tank in unit area, and finally the net radiant heat exchange quantity between each surface of the split oil-immersed transformer oil tank and the wall surface of a room in unit time is confirmed, wherein the formula of the net radiant heat exchange quantity between each surface of the split oil-immersed transformer oil tank and the wall surface of the room in unit time is as follows:

Φ_Σ＝Φ_1,6+Φ_2,6+Φ_3,6+Φ_4,6+Φ_5,6

＝A₁X_1,6(J₁-J₆)+A₂X_2,6(J₂-J₆)+...+A₅X_5,6(J₅-J₆)

wherein phi is_ΣThe net radiation heat exchange quantity between each surface of the split oil-immersed transformer oil tank and the wall surface of a room in unit time is represented; phi is a_1,6Representing the net amount of radiant heat exchange between the first surface and the sixth surface; phi is a_2,6Representing the net amount of radiant heat exchange between the second surface and the sixth surface; phi is a_3,6Representing the net amount of radiant heat exchange between the third surface and the sixth surface; phi is a_4,6Representing the net amount of radiant heat exchange between the fourth surface and the sixth surface; phi is a_5,6Net radiant heat exchange between the fifth surface and the sixth surface; a. the₁Representing the area of the first surface; a. the₂Representing the area of the second surface; a. the₅Represents the area of the fifth surface; j. the design is a square_pRepresenting the total radiant energy emitted per unit area, X, on the p-th surface_p1，pDenotes the p th₁Angle coefficient of surface to pth surface, p₁And p is 1,2,3,4,5,6, and p1 is not equal to p.

The bottom surface radiation heat exchange quantity of the split oil-immersed transformer is not counted, a multi-surface system is formed by the other five surfaces of the split oil-immersed transformer and the wall surfaces of rooms, a model of a split oil-immersed transformer box body is formed, the calculation of the radiation heat dissipation power of the split oil-immersed transformer oil tank is refined, the radiation heat dissipation power of the split oil-immersed transformer oil tank is further calculated after the temperature distribution of each surface of the split oil-immersed transformer oil tank is determined, the average value of the oil tank temperature is adopted in the existing method for calculating the working efficiency of the oil-immersed transformer cooling system, but the change of the actual oil tank temperature along with the height is approximately linear, the change rate of the top temperature and the bottom temperature of the oil tank along with the height is smaller than that of the middle temperature of the oil tank along with the height, the change rule of the oil temperature of the side surface and the front surface, the error caused by calculating the radiation heat dissipation power of the split type oil-immersed transformer oil tank only by using the average temperature of the split type oil-immersed transformer oil tank is avoided, so that the calculation accuracy of the working efficiency of the follow-up split type oil-immersed transformer cooling system is further ensured, and the operating state of the split type oil-immersed transformer can be further controlled by the staff conveniently.

In the embodiment, the convection heat dissipation power P of the transformer oil tank_cCalculated by the convective heat transfer principle.

In this embodiment, in step S7, the actual heat dissipation power P of the cooling system of the split oil-immersed transformer_laThe calculation formula of (2) is as follows:

P_la＝P_z-P_sa

wherein, P_laRepresenting the actual heat dissipation power of the cooling system of the split oil-immersed transformer; p_zRepresenting the heating power of the split oil-immersed transformer; p_saAnd the actual heat dissipation power of the split oil-immersed transformer oil tank is represented.

In this embodiment, in step S8, the formula for solving the working efficiency of the split oil-immersed transformer cooling system is as follows:

η＝P_la/P′_le×100％

and eta represents the working efficiency of the cooling system of the split oil-immersed transformer.

The positional relationships depicted in the drawings are for illustrative purposes only and are not to be construed as limiting the present patent;

it should be understood that the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.

Claims (10)

1. A method for calculating the working efficiency of a cooling system of a split oil-immersed transformer is characterized by at least comprising the following steps:

s1, collecting real-time operation data and nameplate parameters of a split oil immersed transformer;

s2, collecting performance delivery test data and actual operation parameters of the split oil immersed transformer cooling system;

s3, calculating the heating power P of the split oil-immersed transformer based on the real-time operation data and nameplate parameters of the split oil-immersed transformer_z；

S4, determining rated heat dissipation power P of the cooling system of the split oil-immersed transformer based on performance factory test data of the cooling system of the split oil-immersed transformer_le；

S5, according to actual operation parameters of the split oil immersed transformer cooling system, and in combination with influences of oil flow temperature and flow change on delivery rated heat dissipation power of the cooling system during transformer operation, rated heat dissipation power P is obtained_leConversion to actual rated heat dissipation Power P'_le；

S6, obtaining the actual heat dissipation power P of the transformer oil tank based on the results of the infrared temperature measurement radiation and convection calculation of the split oil immersed transformer_sa；

S7, combining actual heat dissipation power P of transformer oil tank_saCalculating the actual heat dissipation power P of the cooling system of the split oil-immersed transformer based on the energy conservation principle_la；

S8, according to actual rated heat dissipation power P'_leAnd the actual heat dissipation power P of the cooling system of the split oil immersed transformer_laAnd solving the working efficiency of the split oil immersed transformer cooling system.

2. The method for calculating the working efficiency of the split oil transformer cooling system according to claim 1, wherein the real-time operation data and nameplate parameters of the split oil transformer comprise: the method comprises the following steps of no-load loss of the split oil-immersed transformer, rated load loss of the split oil-immersed transformer, load value of the split oil-immersed transformer, actual current of the low-voltage side of the split oil-immersed transformer, rated current of the low-voltage side of the split oil-immersed transformer, actual current of the high-voltage side of the split oil-immersed transformer and rated current of the high-voltage side of the split oil-immersed transformer.

3. The method for calculating the operating efficiency of the split oil-immersed transformer cooling system according to claim 2, wherein the heating power P of the split oil-immersed transformer in step S3_zSatisfies the formula:

wherein, P_zRepresenting the heating power of the split oil-immersed transformer; p₀Representing the no-load loss of the split oil-immersed transformer; p_eRepresenting rated load loss of the split oil-immersed transformer; i is_LaRepresenting the actual current of the low-voltage side of the split oil immersed transformer; i is_LeRepresenting the rated current of the low-voltage side of the split oil-immersed transformer; i is_HaRepresenting the actual current of the high-voltage side of the split oil immersed transformer; i is_HeAnd the rated current of the high-voltage side of the split oil-immersed transformer is shown.

4. The method for calculating the working efficiency of the split oil-immersed transformer cooling system according to claim 3, wherein the rated heat dissipation power P of the split oil-immersed transformer cooling system in step S4_leSatisfies the following conditions:

P_le＝P₁-P₂

wherein, P₁Indicating the heating power of the electric heater in the performance factory test data of the split oil-immersed transformer cooling system；P₂And the heat loss of the testing device in the performance factory test data of the split oil-immersed transformer cooling system is shown.

5. The method for calculating the working efficiency of the split oil-immersed transformer cooling system according to claim 4, wherein the rated heat dissipation power P is obtained in step S5_leConversion to actual rated heat dissipation Power P'_leThe formula of (1) is:

wherein, P'_leRepresenting the actual rated heat dissipation power of the cooling system of the split oil-immersed transformer; t is_i'-T_o' represents the actual inlet and outlet oil temperature difference of the cooling system of the split oil-immersed transformer; q_aRepresenting the actual average oil flow of the cooling system of the split oil-immersed transformer; q_eRepresenting rated average oil flow of a cooling system of the split oil-immersed transformer; k represents a correction coefficient;

actual average oil flow Q of split oil-immersed transformer cooling system_aThe solving formula of (2) is as follows:

wherein, T_i、T_o、T_tThe oil temperatures Q and the oil temperatures Q in an oil inlet, an oil outlet and an oil conveying pipe of a cooling system of the split oil immersed transformer in actual operation are respectively_tIs the actual oil flow rate in the oil line.

Rated average oil flow Q of cooling system of split oil-immersed transformer_eThe solving formula of (2) is as follows:

wherein, c_iTo representThe specific heat capacity of transformer oil at an oil inlet of a split type oil immersed transformer cooling system; c. C_oThe specific heat capacity of the transformer oil at the oil outlet of the split type oil immersed transformer cooling system is shown; rho_iThe density of transformer oil at an oil inlet of the split type oil immersed transformer cooling system is represented; rho_oThe density of the transformer oil at the oil outlet of the split type oil-immersed transformer cooling system is shown; p_leThe rated heat dissipation power of the cooling system of the split oil-immersed transformer is represented; t is_i-T_oAnd the temperature difference of the inlet oil and the outlet oil of the cooling system in the performance factory test data of the split oil-immersed transformer cooling system is shown.

6. The method for calculating the working efficiency of the split oil-immersed transformer cooling system according to claim 5, wherein the actual heat dissipation power P of the split oil-immersed transformer oil tank in step S6_saThe satisfied calculation formula is:

P_sa＝P_r+P_c

wherein, P_rRepresenting the radiation heat dissipation power of the split oil-immersed transformer oil tank; p_cAnd the convection heat dissipation power of the split oil-immersed transformer oil tank is shown.

7. The method for calculating the working efficiency of the split oil-immersed transformer cooling system according to claim 6, wherein the radiation heat dissipation power P of the split oil-immersed transformer oil tank_rCalculating by a network method, wherein the wall surfaces of a room in which the split oil-immersed transformer oil tank and the split oil-immersed transformer oil tank are located form a multi-surface system, four side surfaces of the split oil-immersed transformer oil tank are respectively a first surface, a second surface, a third surface and a fourth surface, the top surface of the split oil-immersed transformer oil tank is a fifth surface, the wall surface of the room in which the split oil-immersed transformer oil tank is located is a sixth surface, the temperature distribution condition of each surface of the split oil-immersed transformer oil tank is determined by utilizing infrared temperature measurement, the total radiant emittance emitted by each surface of the split oil-immersed transformer oil tank in unit area is obtained by combining with kirchhoff law, and finally, each surface of the split oil-immersed transformer oilThe formula of the net radiation heat exchange quantity between the wall surfaces of the room and the net radiation heat exchange quantity between each surface of the split oil-immersed transformer oil tank and the wall surfaces of the room in unit time is as follows:

Φ_Σ＝Φ_1,6+Φ_2,6+Φ_3,6+Φ_4,6+Φ_5,6

＝A₁X_1,6(J₁-J₆)+A₂X_2,6(J₂-J₆)+...+A₅X_5,6(J₅-J₆)

wherein phi is_ΣThe net radiation heat exchange quantity between each surface of the split oil-immersed transformer oil tank and the wall surface of a room in unit time is represented; phi is a_1,6Representing the net amount of radiant heat exchange between the first surface and the sixth surface; phi is a_2,6Representing the net amount of radiant heat exchange between the second surface and the sixth surface; phi is a_3,6Representing the net amount of radiant heat exchange between the third surface and the sixth surface; phi is a_4,6Representing the net amount of radiant heat exchange between the fourth surface and the sixth surface; phi is a_5,6Net radiant heat exchange between the fifth surface and the sixth surface; a. the₁Representing the area of the first surface; a. the₂Representing the area of the second surface; a. the₅Represents the area of the fifth surface; j. the design is a square_pRepresenting the total radiant energy emitted per unit area, X, on the p-th surface_p1，pDenotes the p th₁Angle coefficient of surface to pth surface, p₁And p is 1,2,3,4,5,6, and p1 is not equal to p.

8. The method for calculating the working efficiency of the split oil-immersed transformer cooling system according to claim 7, wherein the convective heat dissipation power P of the transformer oil tank_cCalculated by the convective heat transfer principle.

9. The method for calculating the operating efficiency of the split oil transformer cooling system according to claim 6, wherein the actual heat dissipation power P of the split oil transformer cooling system in step S7_laThe calculation formula of (2) is as follows:

P_la＝P_z-P_sa

wherein, P_laRepresenting the actual heat dissipation power of the cooling system of the split oil-immersed transformer; p_zRepresenting the heating power of the split oil-immersed transformer; p_saAnd the actual heat dissipation power of the split oil-immersed transformer oil tank is represented.

10. The method for calculating the working efficiency of the split oil-immersed transformer cooling system according to claim 9, wherein the formula for solving the working efficiency of the split oil-immersed transformer cooling system in step S8 is as follows:

η＝P_la/P′_le×100％

and eta represents the working efficiency of the cooling system of the split oil-immersed transformer.

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