CN112684304A

CN112684304A - Method for evaluating insulation state of vehicle-mounted traction transformer winding under impulse voltage

Info

Publication number: CN112684304A
Application number: CN202011391994.6A
Authority: CN
Inventors: 郭蕾; 蔡丰林; 袁帅
Original assignee: Southwest Jiaotong University
Current assignee: Southwest Jiaotong University
Priority date: 2020-12-02
Filing date: 2020-12-02
Publication date: 2021-04-20
Anticipated expiration: 2040-12-02
Also published as: CN112684304B

Abstract

The invention discloses an evaluation method of the insulation state of a vehicle-mounted traction transformer winding under impulse voltage, which comprises the following steps: the method comprises the steps of obtaining the average working temperature and the average annual voltage impact times of a vehicle-mounted traction transformer during operation according to the operation record of the motor train unit, determining the average leakage current under different impact voltages and impact times in the simulated operation condition, determining the impact accumulation factor of the vehicle-mounted traction transformer, further determining the voltage impact evaluation factor of the vehicle-mounted traction transformer, and finally evaluating the insulation withstand voltage impact performance of a winding of the vehicle-mounted traction transformer. According to the invention, the voltage impact resistance of the insulation of the vehicle-mounted traction transformer winding can be accurately evaluated according to the actual operation condition, and a basis is provided for the selection and evaluation of the insulation of the vehicle-mounted traction transformer winding.

Description

Method for evaluating insulation state of vehicle-mounted traction transformer winding under impulse voltage

Technical Field

The invention belongs to the field of electric insulation on-line monitoring and fault diagnosis, and particularly relates to an evaluation method for an insulation state of a vehicle-mounted traction transformer winding under impulse voltage.

Technical Field

The vehicle-mounted traction transformer is a core component of the motor train unit, is responsible for the safe operation of the motor train unit, and has higher requirements on the safe use of the vehicle-mounted traction transformer along with the rapid development of high-speed rails and the improvement of the safe operation requirements, and the efficiency and the service life of the vehicle-mounted traction transformer are determined by the insulation condition of a winding of the vehicle-mounted traction transformer. Compared with a common power transformer, the vehicle-mounted traction transformer has a severe operating environment, and is greatly influenced by impulse voltage caused by network voltage fluctuation, regenerative braking and excessively equal operating conditions. Research shows that the range of network voltage fluctuation is 19-29 kV, the network voltage fluctuation can reach 32kV during regenerative braking, and when the network voltage fluctuation is over split phase, the impact voltage can even exceed twice rated voltage amplitude, in addition, multiple impact voltages can generate damage accumulation effect on the insulation of the vehicle-mounted traction transformer, the insulation aging can be accelerated, the insulation life can be shortened, and the safe use of the vehicle-mounted traction transformer is influenced. At present, most insulation evaluation researchers for vehicle-mounted traction transformer windings start from a thermal aging angle, convert various conditions encountered by the vehicle-mounted traction transformer into thermal aging influence on insulation, neglect damage accumulation of multiple impulse voltages on the insulation, and because the impulse voltages are high in amplitude, fast in change speed and short in action time, the damage effect of the impulse voltages on the insulation cannot be well reflected by thermal aging equivalence, so that an evaluation method for the insulation state of the vehicle-mounted traction transformer windings under the impulse voltages is urgently needed.

Disclosure of Invention

In view of the above technical problems, the invention aims to provide an evaluation method of an insulation state of a winding of a vehicle-mounted traction transformer under an impulse voltage, which can well evaluate the insulation withstand voltage impulse performance of the winding of the vehicle-mounted traction transformer.

The technical scheme for realizing the invention is as follows:

the first step is as follows: obtaining vehicle-mounted traction transformer operating parameters

Obtaining the average running environment temperature recorded as T according to the running record_meanIn units of K; obtaining the maximum value V of the impulse voltage suffered by the vehicle-mounted traction transformer according to the operation record_max(kV) and minimum value V_min(kV); the average impact time per impact voltage is denoted t_cSetting the value to be 10ms, and setting the time interval of two impact voltages to be 60 s; obtaining the average annual impact times of the windings of the vehicle-mounted traction transformer according to the operation records, and recording the average annual impact times as N_impactIn units of times;

the second step is that: determining a shock accumulation factor S_Vi

Setting m impulse voltages which are uniformly increased and respectively marked as V₁、V₂、V₃、…、V_mIn units of kV, where V₁＝V_min，V_m＝V_max(ii) a The impulse voltage value range is V_min～V_max(ii) a The number of test samples of the vehicle-mounted traction transformer winding insulation material under each impact voltage is set to be 10, and the impact times of the 10 samples under each impact voltage are recorded as H₁、H₂、H₃、…、H₃₀The leakage current measured in time is marked as I_i,j ^qIn units of A, where i represents a surge voltage of V_iI is 1,2,3, …, m, where q represents the surge voltage V_iQ of (1), 2,3, …, 10; wherein j represents the number of impacts H_jThe number of impacts is taken as

The unit is minor-]Is a rounding operation;

the voltage at surge V is obtained by the formula (1)_iThe number of impacts is H_jAverage leakage current I of the sample_i,j；

Calculating the surge voltage V by the formula (2)_iImpact accumulation factor S of_Vi；

The third step: determining a voltage impact evaluation factor C_est

The average modulus length coefficient S is calculated using equation (3)^Δ；

According to the obtained average module length coefficient S^ΔWith the impact accumulation factor S obtained in the second step_ViCalculating the voltage impact evaluation factor C using equation (4)_est；

The fourth step: assessment of on-board traction transformer winding insulation performance

Evaluating the insulation performance of the winding of the vehicle-mounted traction transformer under the impact voltage, and if 0 < C_estIf the voltage impulse resistance is less than or equal to 0.5, the insulation withstand voltage impulse performance of the vehicle-mounted traction transformer winding is good; if 0.5 < C_estIf the voltage impact resistance of the vehicle-mounted traction transformer winding is less than or equal to 1, the insulation voltage impact resistance of the vehicle-mounted traction transformer winding is medium; if C_estIf the voltage is more than 1, the insulation withstand voltage impact performance of the vehicle traction transformer winding is poor, and the insulation use requirement of the vehicle traction transformer winding cannot be met;

the method for evaluating the insulation state of the winding of the vehicle-mounted traction transformer under the impulse voltage has the following advantages: the influence of factors such as temperature, impulse voltage, impulse times and the like on the insulation state of the winding of the vehicle-mounted traction transformer is comprehensively considered, the voltage impulse evaluation factor can be accurately calculated, and a way is provided for evaluating the insulation withstand voltage impulse performance of the winding of the vehicle-mounted traction transformer.

Drawings

Fig. 1 shows a flow chart of a method for evaluating the insulation state of a winding of a traction transformer on board a vehicle under surge voltage.

Detailed Description

The invention is further described with reference to the accompanying drawings and the specific implementation procedures. It should be emphasized that the embodiments described herein are merely illustrative of the invention and do not limit the scope of the inventive concept and its claims.

Obtaining the average running environment temperature recorded as T according to the running record_meanIts value is 365K; obtaining the maximum value V of the impulse voltage suffered by the vehicle-mounted traction transformer according to the operation record_maxIs 50kV and a minimum value V_minIs 35 kV; the average impact time per impact voltage is denoted t_cSetting the value to be 10ms, and setting the time interval of two impact voltages to be 60 s; obtaining the average annual impact times of the windings of the vehicle-mounted traction transformer according to the operation records, and recording the average annual impact times as N_impactThe value is 400 times;

the second step is that: determining a shock accumulation factor S_Vi

The unit is minor-]Is a rounding operation;

The third step: determining a voltage impact evaluation factor C_est

The average modulus length coefficient S is calculated using equation (3)^Δ；

Calculating to obtain a voltage impact evaluation factor C_est0.2, the vehicle-mounted traction transformer winding has good insulation voltage impact resistance.

Claims

1. the evaluation method of the insulation state of vehicle-mounted traction transformer winding under an impulse voltage, is characterized in that, comprises the following steps:

Step 1: Obtain the operating parameters of the on-board traction transformer;

The second step: determine the shock accumulation factor S _Vi ;

The third step: determine the voltage shock evaluation factor C _est ;

Step 4: Evaluate the insulation withstand voltage impulse performance of on-board traction transformer windings;

The specific process of the first step is:

Obtain the average operating ambient temperature according to the operation record, denoted as T _mean , and the unit is K; obtain the maximum value V _max (kV) and the minimum value V _min (kV) of the impulse voltage experienced by the on-board traction transformer according to the operation record; The average impact time is recorded as t _c , and its value is set as 10ms, and the time interval between two impulse voltages is set as 60s; according to the operation records, the average annual impact times of the on-board traction transformer windings are obtained, recorded as N _impact , and the unit is times;

The specific process of the second step is:

Set m uniformly increasing impulse voltages, respectively denoted as V ₁ , V ₂ , V ₃ , ..., V _m , and the unit is kV, where V ₁ =V _min , V _m =V _max ; V _min ~ V _max ; the test samples of the on-board traction transformer winding insulation material under each impulse voltage are set to 10, and the 10 samples under each impulse voltage are recorded as H ₁ , H ₂ , H in the impulse times respectively. ₃ ,..., H ₃₀ , the leakage current measured at 30, denoted as I _i,j ^q , the unit is A, where i represents the impulse voltage V _i , i=1,2,3,...,m, where q represents is the qth sample when the impulse voltage is V _i , q=1,2,3,...,10; where j represents the number of impulses H _j , and the value of the number of impulses is

The unit is times, and [] is the rounding operation;

The average leakage current I _i,j of the sample under the impulse voltage V _i and the impulse number H _j is obtained by formula (1);

By formula (2), calculate the shock accumulation factor S _Vi under the shock voltage _Vi ;

The specific process of the third step is:

Calculate the average modulus S ^Δ using formula (3);

According to the obtained average modulus coefficient S ^Δ and the shock accumulation factor S _Vi obtained in the second step, use formula (4) to calculate the voltage shock evaluation factor C _est ;

The specific process of the fourth step is:

Evaluate the insulation performance of the on-board traction transformer windings under the impulse voltage. If 0<C _est ≤ 0.5, it means that the on-board traction transformer winding insulation withstand voltage impulse performance is good; if 0.5<C _est ≤ 1, it means the on-board traction transformer winding insulation The withstand voltage shock performance is medium; if C _est > 1, it means that the on-board traction transformer winding insulation has poor withstand voltage shock performance and cannot meet the requirements for on-board traction transformer winding insulation.