阅读说明：本技术 适用于动车组车轨接地系统的三维等效电路模型构建方法 (Three-dimensional equivalent circuit model construction method suitable for rail grounding system of motor train unit ) 是由 肖嵩 刘杰 侯昊 申仪想 靳耀耀 周杰 李玉航 叶智宗 童梦园 高国强 于 2021-02-02 设计创作，主要内容包括：本发明公开了一种适用于动车组车轨接地系统的三维等效电路模型构建方法,具体为：基于动车组车体结构特点,将单节车体等效为长方体结构,其中横向边构成车体横向阻抗,竖向边构成车体垂直阻抗,纵向边构成车体纵向阻抗；将车体保护接地和工作接地等效为竖向的保护接地阻抗和工作接地阻抗；钢轨等效为平行钢轨阻抗；利用LCR测试仪分别对车体横向阻抗、车体纵向阻抗、车体垂直阻抗、保护接地阻抗和工作接地阻抗进行测量并计算实际阻抗。本发明更加清晰直观的表达了动车组接地系统的结构特点,能够有效的运用于动车组接地方式的优化设计,来抑制车体回流和减小车体过电压,使得动车组车载电气设备能够安全稳定的运行。(The invention discloses a three-dimensional equivalent circuit model construction method suitable for a rail grounding system of a motor train unit, which specifically comprises the following steps: based on the structural characteristics of the train body of the motor train unit, the single train body is equivalent to a cuboid structure, wherein the transverse edges form transverse impedance of the train body, the vertical edges form vertical impedance of the train body, and the longitudinal edges form longitudinal impedance of the train body; the protection grounding and the working grounding of the vehicle body are equivalent to vertical protection grounding impedance and working grounding impedance; the steel rail is equivalent to parallel steel rail impedance; and respectively measuring the transverse impedance of the vehicle body, the longitudinal impedance of the vehicle body, the vertical impedance of the vehicle body, the protective grounding impedance and the working grounding impedance by using an LCR tester and calculating the actual impedance. The grounding system of the motor train unit clearly and intuitively expresses the structural characteristics of the grounding system of the motor train unit, can be effectively applied to the optimized design of the grounding mode of the motor train unit, and can inhibit the backflow of the motor train unit and reduce the overvoltage of the motor train unit, so that the vehicle-mounted electrical equipment of the motor train unit can safely and stably operate.)

1. The three-dimensional equivalent circuit model construction method suitable for the rail grounding system of the motor train unit is characterized by comprising the following steps of:

step 1: based on the structural characteristics of the train body of the motor train unit, the single train body is equivalent to a cuboid structure, wherein the transverse edge R₁And L₁、R₂And L₂、R₃And L₃、R₄And L₄Form a transverse impedance (11) of the vehicle body and a vertical edge R₅And L₅、R₆And L₆、R₇And L₇、R₈And L₈Forming a vertical resistance (13) of the vehicle body, the longitudinal sides R₉And L₉、R₁₀And L₁₀、R₁₁And L₁₁、R₁₂And L₁₂Forming a longitudinal body impedance (12);

step 2: the protective grounding of the vehicle body is equivalent to a vertical protective grounding impedance (14), and the working grounding is equivalent to a vertical working grounding impedance (18); the steel rails are equivalent to a right-side steel rail impedance (15) and a left-side steel rail impedance (16) which are parallel;

and step 3: the method comprises the following steps of (1) respectively testing parameters of a transverse impedance (11) of a vehicle body, a longitudinal impedance (12) of the vehicle body and a vertical impedance (13) of the vehicle body by using an LCR tester (20) to obtain measurement results; then, two ends of a test line of the LCR tester (20) are short-circuited to obtain the impedance of the test line; subtracting the impedance of the test line from the measurement result to obtain the transverse impedance (11) of the vehicle body, the longitudinal impedance (12) of the vehicle body and the vertical impedance (13) of the vehicle body;

and 4, step 4: respectively testing parameters of the protective grounding impedance (14) and the working grounding impedance (18) by using an LCR tester (20); and subtracting the test line impedance to obtain the protective grounding impedance (14) and the working grounding impedance (18).

2. The method for constructing the three-dimensional equivalent circuit model applicable to the rail grounding system of the motor train unit according to claim 1, wherein the step 3 specifically comprises the following steps:

the measured test line impedance is set to: r and L; the measurement result of the transverse impedance (11) of the vehicle body is R_a，L_aAnd then:

(R₂+jωL₂)//(R₁+jωL₁+R₅+jωL₅+R₆+jωL₆)+R+jωL＝R_a+jωL_a (1)

in the formula, j is a complex imaginary part unit, and omega is an angular frequency;

the measurement result of the longitudinal impedance (12) of the vehicle body is R_b，L_bAnd then:

(R₁₀+jωL₁₀)//(R₅+jωL₅+R₇+jωL₇+R₉+jωL₉)+R+jωL＝R_b+jωL_b (2)

the measurement result of the vertical impedance (13) of the vehicle body is R_c，L_cAnd then:

(R₅+jωL₅)//(R₁+jωL₁+R₂+jωL₂+R₆+jωL₆)+R+jωL＝R_c+jωL_c (3)

because R is₁＝R₂＝R₃＝R₄；L₁＝L₂＝L₃＝L₄；R₅＝R₆＝R₇＝R₈；L₅＝L₆＝L₇＝L₈；R₉＝R₁₀＝R₁₁＝R₁₂；L₉＝L₁₀＝L₁₁＝L₁₂Therefore, the vehicle body transverse resistance R can be obtained by combining the three formulas (1), (2) and (3)₁And L₁(ii) a Vehicle body vertical impedance R₅And L₅(ii) a Longitudinal resistance R of vehicle body₉And L₉。

3. The method for constructing the three-dimensional equivalent circuit model applicable to the rail grounding system of the motor train unit according to claim 1, further comprising: through measurement, the train body impedance and the protective grounding impedance of the motor train unit are calculated, current is manually applied between the train body and the track, different grounding modes, grounding positions and the resistance value of a grounding resistor are tested, the train body voltage and the protective grounding current are measured, and the setting of a grounding system is optimized.

Technical Field

The invention belongs to the technical field of safe operation of an electrified railway motor train unit, and particularly relates to a three-dimensional equivalent circuit model construction method suitable for a rail grounding system of a motor train unit.

Background

The standard motor train unit traction transmission system mainly comprises a traction transformer, a traction converter and a traction motor. Taking a motor train unit (fig. 1) composed of 8 sections as an example, a third train and a sixth train of the motor train unit are provided with traction transformers, the grounding mode is work grounding, the train bodies on two sides of the transformer trains are set as motor trains, and traction converters are arranged to rectify and invert the voltage of secondary side windings of the traction transformers and supply power to traction motors, and the grounding mode is generally series resistance protection grounding. The first vehicle and the eighth vehicle are trailers, and the grounding mode is that the shaft ends are directly grounded. The motor train unit is generally provided with two sets of pantographs, so that only one pantograph can be lifted when the motor train unit normally runs in order to avoid the circulating current short circuit formed by a high-voltage cable on the roof when the motor train unit passes through a split-phase area. When the pantograph of the transformer car rises, the roof high-voltage system takes current from a contact network, the traction current transmits electric energy to traction transformers of the third car and the sixth car after passing through a roof high-voltage cable, a vehicle-mounted vacuum circuit breaker and a disconnecting switch, and the electric energy is converted into alternating-current voltage capable of controlling the running of the train through a rectification inversion process, so that power is supplied to a traction motor to drive the train to run.

The grounding system of the motor train unit can be divided into working grounding and protective grounding according to the application, the working grounding connects the outlet end of the primary winding of the transformer with the grounding device, the primary side traction current of the transformer is led into the wheel pair, sent into the steel rail through the wheel pair and then sent to the traction substation through the steel rail, and the traction current backflow is realized; the protection grounding is to connect the train body of the motor train unit with the grounding device, the train body is a public reference ground of a plurality of strong and weak electric devices on the train, and the protection grounding can ensure that the train body and a steel rail have the same potential under ideal conditions, so that the vehicle-mounted devices are prevented from being interfered by ground potential floating.

The protective grounding is divided according to the grounding structure, and can be divided into a direct grounding mode and a series resistor grounding mode. The direct grounding mode of the motor train unit means that the bottom of the motor train unit body is directly connected with a grounding device through a grounding cable, so that equipotential connection between the motor train unit body and a steel rail is realized. The direct grounding mode is favorable for reducing the electric potential of the vehicle body, particularly under the special transient working condition, transient surge overvoltage is generated on the vehicle body, and the impedance of a grounding loop of the direct grounding mode is low, so that the overvoltage is favorably and quickly released to a steel rail, and the electric potential of the vehicle body is further reduced. However, under normal operating conditions, the car body and the steel rail form a parallel circuit, current on the steel rail enters the car body due to low car body impedance to form car body circulation, and the direct grounding mode has low ground loop impedance to make the car body grounding circulation more serious. The motor train unit series resistance grounding mode is that a grounding resistor is connected in series between the bottom of a motor train unit body and a grounding device on an axle so as to increase the impedance value of the whole protection grounding loop. Under the normal operation condition, the high resistance value of the grounding resistor can effectively inhibit the traction current on the steel rail from flowing back to the vehicle body through the protection grounding. However, because the grounding resistor contains a certain parasitic inductance, under a special transient working condition, the grounding resistor presents an obvious high-frequency impedance characteristic, which is not beneficial to the leakage of the surge overvoltage of the car body to the steel rail through the protection grounding, and causes the overvoltage of the car body to be too high. The train body of the motor train unit is a public reference ground for a plurality of strong and weak current devices on the train, and the over-voltage of the train body is high, so that the insulation damage of the vehicle-mounted devices is easily caused, and the running safety of the motor train unit is seriously influenced. Due to the complex structure of the motor train unit, the overvoltage and the return current of the train rail of the train body are influenced by various factors such as transverse impedance, longitudinal impedance, steel rail impedance, impedance of a train bogie and the like of the train body in the actual running process.

Disclosure of Invention

In order to analyze the influence of overvoltage and rail return on train operation more three-dimensionally and comprehensively and perform optimal design on a grounding system of a motor train unit more intuitively and effectively to achieve the purposes of inhibiting the rail return and reducing the overvoltage of the motor train unit, the invention provides a three-dimensional equivalent circuit model construction method suitable for the rail grounding system of the motor train unit.

The invention discloses a three-dimensional equivalent circuit model construction method suitable for a rail grounding system of a motor train unit, which comprises the following steps of:

step 1: based on the structural characteristics of the train body of the motor train unit, the single train body is equivalent to a cuboid structure, wherein the transverse edge R₁And L₁、R₂And L₂、R₃And L₃、R₄And L₄Forming a transverse impedance of the vehicle body, a vertical edge R₅And L₅、R₆And L₆、R₇And L₇、R₈And L₈Forming a vertical resistance, longitudinal side R of the vehicle body₉And L₉、R₁₀And L₁₀、R₁₁And L₁₁、R₁₂And L₁₂Constituting the longitudinal resistance of the vehicle body.

Step 2: the protective grounding of the vehicle body is equivalent to vertical protective grounding impedance, and the working grounding is equivalent to vertical working grounding impedance; the rails are equivalent to parallel right rail impedance and left rail impedance.

And step 3: respectively testing parameters of the transverse impedance, the longitudinal impedance and the vertical impedance of the car body by using an LCR tester to obtain measurement results; short-circuiting two ends of a test wire of the LCR tester to obtain the impedance of the test wire; and subtracting the impedance of the test line from the measurement result to obtain the transverse impedance of the vehicle body, the longitudinal impedance of the vehicle body and the vertical impedance of the vehicle body.

And 4, step 4: utilizing an LCR tester to test parameters of the protective grounding impedance and the working grounding impedance respectively; and subtracting the impedance of the test line to obtain the protective grounding impedance and the working grounding impedance.

The step 3 specifically comprises the following steps:

the measured test line impedance is set to: r and L; vehicle with wheelsThe measurement result of the bulk transverse impedance is R_a，L_aAnd then:

(R₂+jωL₂)//(R₁+jωL₁+R₅+jωL₅+R₆+jωL₆)+R+jωL＝R_a+jωL_a (1)

where j is the complex imaginary unit and ω is the angular frequency.

The measurement result of the longitudinal impedance of the vehicle body is R_b，L_bAnd then:

(R₁₀+jωL₁₀)//(R₅+jωL₅+R₇+jωL₇+R₉+jωL₉)+R+jωL＝R_b+jωL_b (2)

the measurement result of the vertical impedance of the vehicle body is R_c，L_cAnd then:

(R₅+jωL₅)//(R₁+jωL₁+R₂+jωL₂+R₆+jωL₆)+R+jωL＝R_c+jωL_c (3)

because R is₁＝R₂＝R₃＝R₄；L₁＝L₂＝L₃＝L₄；R₅＝R₆＝R₇＝R₈；L₅＝L₆＝L₇＝L₈；R₉＝R₁₀＝R₁₁＝R₁₂；L₉＝L₁₀＝L₁₁＝L₁₂Therefore, the vehicle body transverse resistance R can be obtained by combining the three formulas (1), (2) and (3)₁And L₁(ii) a Vehicle body vertical impedance R₅And L₅(ii) a Longitudinal resistance R of vehicle body₉And L₉。

Further, the method also comprises the following steps: through measurement, the train body impedance and the protective grounding impedance of the motor train unit are calculated, current is manually applied between the train body and the track, different grounding modes, grounding positions and the resistance value of a grounding resistor are tested, the train body voltage and the protective grounding current are measured, and the setting of a grounding system is optimized.

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

1. the three-dimensional modeling method of the invention expresses the structural characteristics of the grounding system of the motor train unit more clearly and intuitively, can try different grounding schemes that the grounding wheel pairs are distributed on two independent steel rails based on a three-dimensional model, can be effectively applied to the optimization design of the grounding mode of the motor train unit, inhibits the backflow of the motor train unit and reduces the overvoltage of the motor train unit, and ensures that the vehicle-mounted electrical equipment of the motor train unit can operate safely and stably.

2. The three-dimensional model can clearly reflect the different points of the motor train units of different models on the grounding mode, so that the follow-up research and improvement are facilitated.

Drawings

FIG. 1 is an electrical schematic diagram of a motor train unit.

FIG. 2 is a diagram of a motor train unit train body model and a two-dimensional simulation diagram of motor train unit train body impedance.

FIG. 3 is a three-dimensional simulation diagram of the train body impedance of the motor train unit.

FIG. 4 is a model diagram and a two-dimensional simulation diagram of a protective grounding system of a motor train unit.

FIG. 5 is a three-dimensional simulation diagram of the protection grounding system of the motor train unit.

FIG. 6 is a model diagram and a two-dimensional simulation diagram of a grounding system for the motor train unit.

FIG. 7 is a three-dimensional simulation diagram of the working grounding system of the motor train unit.

FIG. 8 is a schematic diagram of testing the lateral impedance of the train body of the motor train unit through the LCR tester.

FIG. 9 is a schematic diagram of testing longitudinal impedance of a motor train unit train body by an LCR tester.

FIG. 10 is a schematic diagram of testing the vertical impedance of the train body of the motor train unit through the LCR tester.

FIG. 11 is a schematic diagram of testing the protective grounding impedance of the motor train unit through the LCR tester.

In the drawings, the numbers are explained as follows: 1-pantograph, 2-high-voltage cable, 3-contact line, 4-rail, 5-traction transformer, 6-bleeder wheel set, 7-traction converter, 8-common wheel set, 9-vehicle body model, 10-vehicle body two-dimensional simulation module, 11-vehicle body transverse impedance, 12-vehicle body longitudinal impedance, 13-vehicle body vertical impedance, 14-protective grounding impedance, 15-right rail impedance, 16-left rail impedance, 17-rail two-dimensional simulation module, 18-working grounding impedance, 19-vehicle transformer secondary side equivalent impedance, 20-LCR tester, 21-bogie, 22-grounding cable, 23-shaft end grounding device, 24-gear box grounding device, 25-grounding resistor, 26-vehicle bottom grounding position and 27-rail wheel set contact point.

Detailed Description

The invention is described in further detail below with reference to the figures and the detailed description.

Fig. 1 is an electrical structure model diagram of an 8-section marshalling standard motor train unit, wherein one, two, four, five, seven and eight are non-working grounding compartments, one and eight are trailer compartments, the protective grounding is in a shaft end direct grounding mode, the two, four, five and seven are motor train compartments, the protective grounding is in a series resistance grounding mode, and the three and six are working grounding compartments.

The left side of the diagram 2 is a motor train unit train body model diagram, the right side is a train body impedance two-dimensional simulation diagram, a standard motor train unit train body adopts an aluminum alloy structure, and a single-section carriage is 25.5m long, 4.4m high and 3.1m wide. The difference of the transverse and longitudinal lengths of the car body causes the difference of the transverse and longitudinal impedance parameters of the car body to be larger. Under transient conditions such as a lifting bow and the like, overvoltage is injected into a vehicle body from a grounding point of vehicle roof equipment, and the overvoltage is obviously different from the overvoltage in the longitudinal direction and the transverse direction of the vehicle body.

Based on the structural characteristics of the train body of the motor train unit, the invention enables the single train body to be equivalent to a cuboid structure as shown in figure 3, wherein the transverse edge R₁And L₁、R₂And L₂、R₃And L₃、R₄And L₄Form the transverse impedance 11 and the vertical edge R of the vehicle body₅And L₅、R₆And L₆、R₇And L₇、R₈And L₈Forming a vertical resistance 13 of the vehicle body, a longitudinal edge R₉And L₉、R₁₀And L₁₀、R₁₁And L₁₁、R₁₂And L₁₂Constituting a longitudinal body impedance 12.

The standard motor train unit is provided with 4 grounding devices under each section of train, as shown in fig. 4, a grounding system equivalent model and two-dimensional simulation of a non-working grounding carriage are shown, and as shown in fig. 5, a grounding system three-dimensional simulation of the non-working grounding carriage is shown. The protective grounding 14 of the trailer carriage is completely in a shaft end direct grounding mode, the bottom 26 of the trailer body is directly connected with a shaft end grounding device 23 through a grounding cable 22, and then the trailer body is grounded through the grounding device 23 and a wheel pair steel rail contact point 27. The protective grounding 14 of the motor car body is in a series resistance grounding mode, a grounding cable 22 is used for connecting the bottom 26 of the car body with one end of a grounding resistor 25, the other end of the grounding resistor 25 is connected with a grounding device at a driving shaft gear box 24 through the grounding cable 22, and then the grounding device 23 and a contact point 27 of a steel rail wheel pair are connected to realize the grounding of the motor car body. The motor train unit shafts 1, 2, 3 and 4 are all connected with a protective grounding 14, wherein the protective grounding 14 of the shafts 1 and 3 is connected with a right-side steel rail 15, and the protective grounding 14 of the shafts 2 and 4 is connected with a left-side steel rail 16.

Fig. 6 shows an equivalent model and a two-dimensional simulation of a grounding system with a working grounded car, and fig. 7 shows a three-dimensional simulation of a grounding system with a working grounded car. The working grounding mainly functions to provide a return flow channel from the low-voltage end of the transformer to the steel rail for traction current, 3 grounding return lines are led out from the outlet end of the primary side winding of the transformer and are respectively connected to grounding devices at No. 2, No. 3 and No. 4 shaft ends under the vehicle, and the grounding devices are connected with the steel rail through a grounding carbon brush and a wheel pair to form a working grounding loop. Wherein the 1-axis protective earth 14 and the 3-axis working earth 18 are connected to the right side rail 15 and the 2-axis and 4-axis working earth 18 are connected to the left side rail 16.

The LCR tester 20 is used to test the parameters of the transverse car body impedance 11, the longitudinal car body impedance 12 and the vertical car body impedance 13 to obtain the measurement results, which are respectively shown in fig. 8, 9 and 10. During testing, because the vehicle body is longer, the required long test line has certain impedance, after the measurement result is recorded, the two ends of the test line of the LCR tester 20 are short-circuited to obtain the impedance of the test line; and subtracting the impedance of the test line from the measurement result to obtain the transverse impedance 11 of the vehicle body, the longitudinal impedance 12 of the vehicle body and the vertical impedance 13 of the vehicle body.

The measured test line impedance is set to: r and L; the measurement result of the vehicle body transverse impedance 11 is R_a，L_aAnd then:

(R₂+jωL₂)//(R₁+jωL₁+R₅+jωL₅+R₆+jωL₆)+R+jωL＝R_a+jωL_a (1)

the measurement result of the longitudinal impedance 12 of the vehicle body is R_b，L_bAnd then:

(R₁₀+jωL₁₀)//(R₅+jωL₅+R₇+jωL₇+R₉+jωL₉)+R+jωL＝R_b+jωL_b (2)

the measurement result of the vehicle body vertical impedance 13 is R_c，L_cAnd then:

(R₅+jωL₅)//(R₁+jωL₁+R₂+jωL₂+R₆+jωL₆)+R+jωL＝R_c+jωL_c (3)

because R is₁＝R₂＝R₃＝R₄；L₁＝L₂＝L₃＝L₄；R₅＝R₆＝R₇＝R₈；L₅＝L₆＝L₇＝L₈；R₉＝R₁₀＝R₁₁＝R₁₂；L₉＝L₁₀＝L₁₁＝L₁₂Therefore, the vehicle body transverse resistance R can be obtained by combining the three formulas (1), (2) and (3)₁And L₁(ii) a Vehicle body vertical impedance R₅And L₅(ii) a Longitudinal resistance R of vehicle body₉And L₉。

As shown in fig. 11, the protective grounding impedance 14 of the motor train unit is tested by using an LCR tester 20, and probes of the LCR tester 20 are respectively added at a vehicle bottom grounding position 26 and a wheel set and steel rail contact point 27. The result obtained in the process of testing each part of parameters is the sum of the parameters of the grounding loop and the parameters of the test line, and the parameters of the grounding loop can be obtained by subtracting the parameters of the test line from the obtained parameters.

Through measurement, the train body impedance and the protective grounding impedance of the motor train unit are calculated, a certain amount of current is applied between the train body and the track manually, different grounding modes, grounding positions and the resistance value of a grounding resistor are tested, the train body voltage and the protective grounding current are measured, and the optimal grounding system setting is achieved.

The invention has the advantages of synergy relative to two-dimensional modeling:

the grounding system of the motor train unit is huge, the number of devices is large, parameters are mutually coupled, numerical calculation is mostly nonlinear transformation, an accurate mathematical model is difficult to establish for calculation, and the mathematical model is established on an ideal model and principle, so that compared with a two-dimensional model which ignores transverse and vertical impedance parameters of a rail, the establishment of a more accurate and intuitive three-dimensional model becomes necessary. The motor train units running on the high-speed railway in China have various models, the grounding modes of the motor train units are different when the models are different, the difference of the grounding modes of the motor train units of different models is hardly reflected by common two-position modeling, but the difference and the same point of the motor train units of different models on the grounding mode can be clearly reflected by a three-dimensional model, so that the follow-up research and improvement are facilitated.

The running working condition of the motor train unit is complex, the motor train unit can be influenced by various factors in the actual running process, and compared with two-bit modeling, the problem that the impedance three-dimensional modeling of the grounding system of the motor train unit can consider is more comprehensive and has a guiding function. For example, the traction current flows from the grounding system to the rails, the traction current flowing through the two rails may be unbalanced due to the existence of the lateral impedance of the car body and the rails, and when the unbalanced current coefficient is greater than 5%, the signal equipment may be damaged and interfered, such as the red light band of the track circuit or the burning equipment of the high current invasion. The two-dimensional simulation and the three-dimensional simulation comparison of the train body impedance of the motor train unit show that the two-dimensional simulation of the train body impedance expressing a single expression can not reflect important influence factors such as transverse impedance and longitudinal impedance of the train body.