Method for evaluating overload resistance of distribution transformer in high-altitude environment

Abstract

The invention discloses a method for evaluating the overload resistance of a distribution transformer in a high-altitude environment, and the method comprises the steps: simulating the operation of the distribution transformer in different high-altitude environments, and obtaining a power factor evaluation factor and a hot-spot temperature evaluation factor of the distribution transformer in different high-altitude environments; and finally determining an overload-resistant capability evaluation factor of the distribution transformer, and verifying the overload-resistant capability of the distribution transformer. According to the method, the overload resistance of the distribution transformer is evaluated by using the overload resistance evaluation factor of the distribution transformer, so that the overload resistance of the distribution transformer in the high-altitude environment can be accurately and quickly evaluated, and a basis is provided for evaluation and selection of the distribution transformer in the high-altitude environment.

Description

Technical Field

[0001] The present invention belongs to the field of overload resistance performance test and evaluation of electrical equipment, and in particular relates to a method for evaluating the overload resistance capacity of a distribution transformer in a high-altitude environment. Background Art

[0002] High altitude areas have the characteristics of low air pressure and thin air, large temperature fluctuations, strong sunshine, and extremely low temperature at night. Due to the low oxygen content in high altitude areas, the thermal conductivity of the insulation material will also be reduced, affecting the heat dissipation of the distribution transformer, which will lead to an increase in the winding temperature of the distribution transformer; and the environment in high altitude areas is relatively dry, which will cause the insulation material of the distribution transformer to age and deteriorate, and the insulation performance will decrease. The low air pressure will reduce the electrical clearance of the electrical equipment, and insulation breakdown is prone to occur; thereby reducing the overload resistance of the distribution transformer and affecting the normal operation of the distribution transformer. With the increasing demand for distribution transformers in high altitude environments, the overload problem of distribution transformers has become increasingly prominent. Evaluating the overload resistance of distribution transformers operating in high altitude environments is a necessary means to ensure the safe and reliable operation of distribution transformers, and distribution transformers suitable for high altitude environments can be selected. However, there is currently a lack of effective evaluation methods for the overload resistance of distribution transformers in high altitude environments. Therefore, there is an urgent need for an evaluation method for the overload resistance of distribution transformers in high altitude environments. Summary of the invention

[0003] In view of the above technical problems, the purpose of the present invention is to propose a method for evaluating the overload resistance capacity of a distribution transformer in a high-altitude environment, which can effectively evaluate the overload resistance capacity of a distribution transformer, and is characterized in that it includes the following steps:

[0004] Step 1: Obtain the operating parameters of the distribution transformer

[0005] According to the operation records, the average hot spot temperature of the distribution transformer winding is obtained, which is recorded as T0 in K; according to the operation records, the average load multiple of the distribution transformer is obtained, which is recorded as K0; according to the operation records, the average atmospheric pressure of the distribution transformer operating environment is obtained, which is recorded as P0 in kPa; according to the operation records, the average power factor of the distribution transformer is obtained, which is recorded as cosφ0;

[0006] Step 2: Determine the power factor evaluation factor of the distribution transformer in different high altitude environments

[0007] Simulate a distribution transformer with an overload multiple of 1.6 and a continuous operating time of 45 minutes to operate in different high-altitude environments. Use different atmospheric pressures to simulate different high-altitude environments. Set 6 groups of decreasing atmospheric pressures P i, respectively P1 = 78.9 kPa, P2 = 72.84 kPa, P3 = 67.24 kPa, P4 = 61.64 kPa, P5 = 56.04 kPa, P6 = 50.44 kPa, measuring the power factor of the distribution transformer under different atmospheric pressure environments i=1,2,3,4,5,6, is the power factor of the distribution transformer corresponding to the atmospheric pressure P1;

[0008] The power factor evaluation factor μ under different high altitude environments is obtained by formula (1):

[0009]

[0010] Step 3: Determine the hot spot temperature evaluation factor of the distribution transformer under different high altitude environments

[0011] Simulate a distribution transformer with an overload multiple of 1.6 and a continuous operating time of 45 minutes to operate in different high-altitude environments. Use different atmospheric pressures to simulate different high-altitude environments. Set 6 groups of decreasing atmospheric pressures P j , respectively P1 = 78.9 kPa, P2 = 72.84 kPa, P3 = 67.24 kPa, P4 = 61.64 kPa, P5 = 56.04 kPa, P6 = 50.44 kPa, measuring the corresponding distribution transformer winding hot spot temperature T under different atmospheric pressure environments j , the unit is K, j = 1, 2, 3, 4, 5, 6, T1 is the hot spot temperature of the distribution transformer winding corresponding to the atmospheric pressure P1;

[0012] The hotspot temperature evaluation factor β under different high altitude environments is obtained by formula (2):

[0013]

[0014] Step 4: Determine the overload capacity assessment factor of the distribution transformer

[0015] Use formula (3) to calculate the distribution transformer overload capacity assessment factor α:

[0016]

[0017] Step 5: Evaluate the overload capacity of the distribution transformer

[0018] The overload capacity of the distribution transformer in a high-altitude environment is evaluated according to formula (3). If α≤13.7, it is considered that the overload capacity of the distribution transformer in a high-altitude environment is qualified. Otherwise, it is considered that there is a problem and it needs to be improved or the material replaced.

[0019] The beneficial effect of the present invention is that it takes into account the actual operating environment of the distribution transformer and proposes an evaluation method for the overload resistance capacity of the distribution transformer in a high-altitude environment, which can provide necessary data support for the production design optimization and overload resistance capacity evaluation of the distribution transformer. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The figure shows a flow chart of a method for evaluating the overload capability of distribution transformers in high altitude environments. DETAILED DESCRIPTION

[0021] The present invention is further described below in conjunction with the accompanying drawings and specific implementation processes; it should be emphasized that the specific implementation cases described herein are only used to explain the present invention and do not limit the scope of the present invention and its claims; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the accompanying drawings are omitted. A method for evaluating the overload resistance of a distribution transformer in a high altitude environment comprises the following steps:

[0022] Step 1: Obtain the operating parameters of the distribution transformer

[0023] According to the operation records, the average hot spot temperature of the distribution transformer winding is obtained, which is recorded as T0 in K. According to the operation records, the average load multiple of the distribution transformer is obtained, which is recorded as K0. According to the operation records, the average atmospheric pressure of the distribution transformer operating environment is obtained, which is recorded as P0 in kPa. According to the operation records, the average power factor of the distribution transformer is obtained, which is recorded as

[0024] Step 2: Determine the power factor evaluation factor of the distribution transformer in different high altitude environments

[0025] Simulate a distribution transformer with an overload multiple of 1.6 and a continuous operating time of 45 minutes to operate in different high-altitude environments. Use different atmospheric pressures to simulate different high-altitude environments. Set 6 groups of decreasing atmospheric pressures P i , respectively P1 = 78.9 kPa, P2 = 72.84 kPa, P3 = 67.24 kPa, P4 = 61.64 kPa, P5 = 56.04 kPa, P6 = 50.44 kPa, measuring the power factor of the distribution transformer under different atmospheric pressure environments i=1,2,3,4,5,6, is the power factor of the distribution transformer corresponding to the atmospheric pressure P1;

[0026] The power factor evaluation factor μ under different high altitude environments is obtained by formula (1):

[0027]

[0028] Step 3: Determine the hot spot temperature evaluation factor of the distribution transformer under different high altitude environments

[0029] Simulate a distribution transformer with an overload multiple of 1.6 and a continuous operating time of 45 minutes to operate in different high-altitude environments. Use different atmospheric pressures to simulate different high-altitude environments. Set 6 groups of decreasing atmospheric pressures P j , respectively P1 = 78.9 kPa, P2 = 72.84 kPa, P3 = 67.24 kPa, P4 = 61.64 kPa, P5 = 56.04 kPa, P6 = 50.44 kPa, measuring the corresponding distribution transformer winding hot spot temperature T under different atmospheric pressure environments j , the unit is K, j = 1, 2, 3, 4, 5, 6, T1 is the hot spot temperature of the distribution transformer winding corresponding to the atmospheric pressure P1;

[0030] The hotspot temperature evaluation factor β under different high altitude environments is obtained by formula (2):

[0031]

[0032] Step 4: Determine the overload capacity assessment factor of the distribution transformer

[0033] Use formula (3) to calculate the distribution transformer overload capacity assessment factor α:

[0034]

[0035] Step 5: Evaluate the overload capacity of the distribution transformer

[0036] The overload capacity of the distribution transformer in a high-altitude environment is evaluated according to formula (3). If α≤13.7, it is considered that the overload capacity of the distribution transformer in a high-altitude environment is qualified. Otherwise, it is considered that there is a problem and it needs to be improved or the material replaced.

[0037] The beneficial effect of the present invention is that it takes into account the actual operating environment of the distribution transformer and proposes an evaluation method for the overload resistance capacity of the distribution transformer in a high-altitude environment, which can provide necessary data support for the production design optimization and overload resistance capacity evaluation of the distribution transformer.

Claims

1. A method for evaluating the overload resistance of a distribution transformer in a high altitude environment, characterized in that: The following steps are involved: Step 1: Obtain the operating parameters of the distribution transformer According to the operation records, the average hot spot temperature of the distribution transformer winding is obtained, which is recorded as T0 in K. According to the operation records, the average load multiple of the distribution transformer is obtained, which is recorded as K0; according to the operation records, the average atmospheric pressure of the distribution transformer operating environment is obtained, which is recorded as P0, in kPa; according to the operation records, the average power factor of the distribution transformer is obtained, which is recorded as Step 2: Determine the power factor evaluation factor of the distribution transformer in different high altitude environments Simulate a distribution transformer with an overload multiple of 1.6 and a continuous operating time of 45 minutes to operate in different high-altitude environments. Use different atmospheric pressures to simulate different high-altitude environments. Set 6 groups of decreasing atmospheric pressures P i , respectively P1 = 78.9 kPa, P2 = 72.84 kPa, P3 = 67.24 kPa, P4 = 61.64 kPa, P5 = 56.04 kPa, P6 = 50.44 kPa, measuring the power factor of the distribution transformer under different atmospheric pressure environments i=1,2,3,4,5,6, is the power factor of the distribution transformer corresponding to the atmospheric pressure P1; The power factor evaluation factor μ under different high altitude environments is obtained by formula (1): Step 3: Determine the hot spot temperature evaluation factor of the distribution transformer under different high altitude environments Simulate a distribution transformer with an overload multiple of 1.6 and a continuous operating time of 45 minutes to operate in different high-altitude environments. Use different atmospheric pressures to simulate different high-altitude environments. Set 6 groups of decreasing atmospheric pressures P j , respectively P1 = 78.9 kPa, P2 = 72.84 kPa, P3 = 67.24 kPa, P4 = 61.64 kPa, P5 = 56.04 kPa, P6 = 50.44 kPa, measuring the corresponding distribution transformer winding hot spot temperature T under different atmospheric pressure environments j , the unit is K, j = 1, 2, 3, 4, 5, 6, T1 is the hot spot temperature of the distribution transformer winding corresponding to the atmospheric pressure P1; The hotspot temperature evaluation factor β under different high altitude environments is obtained by formula (2): Step 4: Determine the overload capacity assessment factor of the distribution transformer Use formula (3) to calculate the overload capacity assessment factor α of the distribution transformer: Step 5: Evaluate the overload capacity of the distribution transformer The overload capacity of the distribution transformer in a high-altitude environment is evaluated according to formula (3). If α≤13.7, it is considered that the overload capacity of the distribution transformer in a high-altitude environment is qualified. Otherwise, it is considered that there is a problem and it needs to be improved or the material replaced.

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