CN116316499A - Method for restraining operation overvoltage high-voltage side of motor train unit - Google Patents
Method for restraining operation overvoltage high-voltage side of motor train unit Download PDFInfo
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- H02H9/04—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess voltage
Abstract
The invention provides a method for restraining an overvoltage high-voltage side of a motor train unit operation, and belongs to the technical field of motor train unit overvoltage restraining. The invention starts from an operation overvoltage propagation path, researches a general means for restraining the operation overvoltage, designs and prepares a restraining device taking an inductor as a main body through theoretical calculation, and performs impedance analysis on the device, thereby solving the problem that the current researches on the operation overvoltage restraining means mostly carry out overvoltage restraining on a low-voltage part of a vehicle bottom, but the general restraining means is difficult to form systematic for the operation overvoltage due to the difference of different vehicle body protection grounding modes.
Description
Technical Field
The invention belongs to the technical field of overvoltage suppression of motor train units, and particularly relates to a method for suppressing an overvoltage high-voltage side of operation of a motor train unit.
Background
The main capacity of railway transportation in China is a high-speed motor train unit, strong current, weak current and various electric devices coexist on the high-speed motor train unit, and most of electric devices treat the motor train unit body as a public ground, so that the electromagnetic compatibility of the devices is numerous. The overvoltage causes unstable public ground potential of the vehicle body due to the propagation path, and the problem of equipment disturbance is serious.
Numerous studies are currently underway to suppress overvoltage, and the japanese scholars Hatsukade S indicate that AC vehicles can effectively suppress body surge overvoltage through low-impedance SIC grounding resistor grounding; yang Shuai et al propose that the method for reducing the grounding resistor of the motor train unit can inhibit surge overvoltage of the motor train unit to a certain extent, and the resistance value of the grounding resistor of the motor train unit should be 0.5 ohm more reasonably; the method comprises the steps that a switching surge simulation model of a direct current rapid train is built by a Maxime Berger of university of Montreal, canada, and the influence of the surge overvoltage of a train body on a direct current train electronic device is analyzed based on the model; the Gao Guojiang team of southwest traffic university explores the overvoltage characteristics of the train body where the high-voltage cable is located, and further analyzes the influence rule of factors such as the network voltage phase of the contact network, the excitation inductance of the traction transformer, the distributed capacitance of the high-voltage cable and the like on the overvoltage characteristics of the operation of disconnecting the VCB; shi Dan is mainly used for researching overvoltage characteristics of a high-voltage system when the circuit breaker is operated, and a corresponding inhibition scheme is provided; liang Jianying proposes measures for suppressing an overvoltage of a vehicle body: the head car body is provided with a surge device which is used for protecting the ground and can discharge surge voltage; zheng the effect of the grounding system on the body overvoltage was analyzed to conclude that: the addition of the grounding point can inhibit the overvoltage of the vehicle body to a certain extent, and the inhibition effect of the grounding point of the vehicle where the lightning arrester is positioned is most obvious; shen Hanlin et al analyzed the effect of the shunt capacitance of the ground resistor on the overvoltage, concluding that: with the increase of the capacitance value of the parallel capacitor, the peak value of the overvoltage of the train body appears later and later, and the impact of the overvoltage on the motor train unit is effectively restrained.
It is not difficult to find that the current research on the means for suppressing the overvoltage is mostly to perform overvoltage suppression on a low-voltage part of the vehicle bottom, such as changing a protection grounding path and a mode to suppress the overvoltage, optimizing the protection grounding distribution and the grounding impedance under the vehicle, and mostly only optimizing the overvoltage peak value of the shaft end, so that effective overvoltage suppression is formed on equipment with a grounding point at the shaft end, such as a speed sensor. However, the lateral overvoltage of the vehicle body, which affects many other vehicle-mounted devices, is not effectively suppressed because the means for suppressing the overvoltage in the low-voltage portion under the vehicle does not start from the propagation path of the overvoltage to the vehicle body, and the propagation of the overvoltage cannot be suppressed from the source. And because the number of the car body protection grounding is numerous, different car body protection grounding modes are different, and a systematic general suppression means is difficult to form for the operation overvoltage.
Disclosure of Invention
Aiming at the defects in the prior art, the method for inhibiting the operation overvoltage high-voltage side of the motor train unit solves the problems that most of the current researches on the operation overvoltage inhibiting means are to inhibit the overvoltage at the low-voltage part of the vehicle bottom, but the common inhibiting means are difficult to form systematically on the operation overvoltage due to the difference of different vehicle body protection grounding modes.
In order to achieve the above purpose, the invention adopts the following technical scheme:
the scheme provides a method for restraining an overvoltage high-voltage side of a motor train unit operation, which comprises the following steps:
s1, closing a circuit breaker;
s2, generating overvoltage in the high-voltage cable core wire;
s3, coupling the generated overvoltage to the shielding layer through a distributed capacitor of the high-voltage cable core wire and the shielding layer;
s4, transmitting an overvoltage signal on the shielding layer to the vehicle body through a grounding wire between the shielding layer and the vehicle body;
s5, a suppression device is connected in series on the grounding line, and the suppression device is utilized to share an overvoltage signal, so that suppression of the operation overvoltage high-voltage side of the motor train unit is completed, wherein the suppression device and the vehicle body form a series connection relationship, and the impedance of the suppression device is larger than that of the vehicle body.
The beneficial effects of the invention are as follows: the invention starts from the high-voltage side through a propagation path to the motor train unit operation overvoltage, and a suppression device taking an inductance as a main body is connected in series between a high-voltage cable shielding layer and a ground wire of a vehicle body, and the ground mode is changed from direct ground to inductance ground. The invention solves the problems that the prior researches on the operation overvoltage suppression means mostly carry out overvoltage suppression on a low-voltage part of the vehicle bottom, but the common suppression means for systematic operation overvoltage is difficult to form due to the difference of different vehicle body protection grounding modes.
Further, the design method of the suppression device is as follows:
a1, collecting vehicle body overvoltage data;
a2, establishing a simulation model, and optimizing the simulation model by utilizing the collected overvoltage data;
a3, respectively obtaining parameters of the vehicle body, the impedance of the grounding system and distribution parameters of the contact net to the vehicle body by using the optimized simulation model;
a4, setting the inductance of the suppression device according to the result obtained in the step A3;
a5, based on the suppression device with the inductance value set, installing the suppression device with the inductor as a main body between the high-voltage cable shielding layer and the vehicle body grounding wire;
a6, utilizing an installed suppressing device to reduce the overvoltage of the vehicle body in a voltage division mode;
a7, simulating the overvoltage of the vehicle body of the installation suppression device;
a8, comparing the simulation result with original vehicle body simulation data, confirming the effectiveness of the suppression device, and selecting an inductance value interval of the suppression device;
and A9, designing a real object of the suppression device according to the inductance value interval, and completing the design of the suppression device.
The beneficial effects of the above-mentioned further scheme are: the invention confirms the effectiveness of the inhibition device through the design.
Still further, the expression of the impedance of the suppressing means is as follows:
Z L ≥Z C +Z G
wherein Z is L Represents the impedance of the suppression device, Z C Represents the impedance of the vehicle body, Z G Representing the ground system impedance.
The beneficial effects of the above-mentioned further scheme are: the impedance of the suppressing device is an important parameter in voltage division, and in order to significantly reduce the overvoltage component on the vehicle body, the impedance of the suppressing device should be equal to or greater than the impedance of the vehicle body and the ground system.
Still further, the step A4 includes the steps of:
a401, calculating the distributed capacitance between the contact net and the car body according to the result obtained in the step A3;
a402, obtaining the inductance of the suppression device according to the distributed capacitance and the impedance of the suppression device.
Still further, the distributed capacitance is expressed as follows:
wherein C represents the capacitance of a capacitor having a pitch dz, ε represents the integral of dz from 0 to h, ε represents the air dielectric constant, S represents the planar area between two plates of the distributed capacitance, dz represents the micro-element distance between the overhead contact line and the vehicle body, r represents the radius of the overhead contact line, h represents the overhead contact line-to-roof pitch, b represents the width of the vehicle body, a represents the length of the vehicle body, and l represents the length of the overhead contact line.
Still further, the body of the suppression device is provided as a spiral wound loop inductor of a spiral coil wound around a magnetic core, wherein an inductance expression of the spiral coil is as follows:
wherein L is 0 Represents the inductance of the spiral coil, mu 0 Represents vacuum permeability, mu r Indicating the relative magnetic permeability of the magnetic core, N indicating the number of turns of the spiral coil, h indicating the height of the magnetic core, r 1 Represents the outer radius of the magnetic core, r 2 Indicating the core inner radius.
Drawings
Fig. 1 is a schematic diagram of an overvoltage propagation path circuit in the present embodiment.
Fig. 2 is a flow chart of the method of the present invention.
Fig. 3 is a schematic diagram illustrating the working principle of the suppression device in this embodiment.
Fig. 4 is a schematic diagram of equivalent impedance of the vehicle body in the present embodiment.
Fig. 5 is an equivalent impedance diagram of the grounding system in the present embodiment.
Fig. 6 is a schematic diagram of the equivalent impedance of the whole vehicle in the present embodiment.
Fig. 7 is a schematic diagram of an overvoltage coupling path in the present embodiment.
Fig. 8 is a schematic diagram of an integration region in the present embodiment.
Fig. 9 is a schematic diagram of an operation overvoltage simulation circuit in the present embodiment.
Fig. 10 is an equivalent circuit diagram of the inductor in the present embodiment.
Fig. 11 is a schematic diagram of a main body model of the suppressing apparatus in the present embodiment.
Fig. 12 is a schematic diagram showing inductance of the suppression device at different magnetic core relative permeability in the present embodiment.
Fig. 13 is a graph showing the relative permeability of the iron core material according to the present embodiment.
Fig. 14 is a schematic diagram of a physical body of the suppressing apparatus in this embodiment.
Fig. 15 is a schematic diagram of a parameter verification ground test of the suppression device in this embodiment.
Fig. 16 is a schematic diagram of the impedance curve of the suppression device in this embodiment.
Detailed Description
The following description of the embodiments of the present invention is provided to facilitate understanding of the present invention by those skilled in the art, but it should be understood that the present invention is not limited to the scope of the embodiments, and all the inventions which make use of the inventive concept are protected by the spirit and scope of the present invention as defined and defined in the appended claims to those skilled in the art.
Examples
The invention analyzes the generation mechanism of the operation overvoltage, starts from the propagation path of the overvoltage, and develops a general operation overvoltage suppression mode. The main circuit breaker is frequently operated when the brake lifting bow is started before and after passing through the phase separation of the motor train unit. When the circuit breaker acts, the state of a traction side circuit of the motor train unit is changed drastically, and overvoltage, namely operation overvoltage, is generated in a high-voltage system, a vehicle body and a grounding system. When the circuit breaker is closed, the high-voltage system causes zero state response under the action of an external excitation source, and then a high-frequency oscillation process occurs in the loop, so that operation overvoltage is generated, the magnitude of the operation overvoltage value of the circuit breaker is related to the phase angle when the circuit breaker is closed, and inductive and capacitive elements in the circuit. The process of opening a circuit breaker is similar to one common operation of cutting off an empty-load transformer in a power system. The cutting off of the no-load transformer is to cut off a small current of an inductive load, the current value is very small, the arc extinguishing capability of the circuit breaker is extremely high, so that the no-load current is cut off when the zero crossing is not performed, namely a so-called cut-off phenomenon is generated, and high overvoltage is generated. The peak value of the off overvoltage is related to the cut-off phase angle, the circuit resonant frequency and the damping coefficient. Both operating overvoltages are inversely related to the equivalent distributed capacitance of the transformer and the high-voltage cable core to ground capacitance. Because the shielding layer of the roof high-voltage cable is connected with the vehicle body, the operation overvoltage can be coupled to the shielding layer through the distributed capacitance between the core wire of the high-voltage cable and the shielding layer, and then propagated to the vehicle body through the connecting path of the shielding layer and the vehicle body, the process can be equivalent to the distributed capacitance C of the core wire through the core wire and the shielding layer d A passage is formed to discharge the vehicle body. The shielding layers of the high-voltage cable are not continuous, and each shielding layer is directly connected with a single point of the vehicle body, so that the coupling path can be regarded as a multi-section parallel circuit, as shown in fig. 1.
As shown in fig. 2, the invention provides a method for restraining an overvoltage high-voltage side of a motor train unit operation, which comprises the following steps:
s1, closing a circuit breaker;
s2, generating overvoltage in the high-voltage cable core wire;
s3, coupling the generated overvoltage to the shielding layer through a distributed capacitor of the high-voltage cable core wire and the shielding layer;
s4, transmitting an overvoltage signal on the shielding layer to the vehicle body through a grounding wire between the shielding layer and the vehicle body;
s5, a suppression device is connected in series on the grounding line, and the suppression device is utilized to share an overvoltage signal, so that suppression of the operation overvoltage high-voltage side of the motor train unit is completed, wherein the suppression device and the vehicle body form a series relation, the impedance of the suppression device is larger than that of the vehicle body, and the impedance of the suppression device is expressed as follows:
Z L ≥Z C +Z G
wherein Z is L Represents the impedance of the suppression device, Z C Represents the impedance of the vehicle body, Z G Representing the ground system impedance.
In this embodiment, the design method of the suppression device is as follows:
a1, collecting vehicle body overvoltage data;
a2, establishing a simulation model, and optimizing the simulation model by utilizing the collected overvoltage data;
a3, respectively obtaining parameters of the vehicle body, the impedance of the grounding system and distribution parameters of the contact net to the vehicle body by using the optimized simulation model;
a4, setting the inductance of the suppression device according to the result obtained in the step A3, wherein the implementation method is as follows:
a401, calculating the distributed capacitance between the contact net and the car body:
wherein C represents the capacitance of a capacitor with a pitch dz, C represents the integration of dz from 0 to h, epsilon represents the air dielectric constant, S represents the planar area between two plates of the distributed capacitance, dz represents the micro-element distance between the overhead contact line and the vehicle body, r represents the radius of the overhead contact line, h represents the overhead contact line to roof pitch, b represents the width of the vehicle body, a represents the length of the vehicle body, and l represents the length of the overhead contact line;
a402, obtaining the inductance of the suppression device according to the distributed capacitance and the impedance of the suppression device;
a5, based on the suppression device with the inductance value set, installing the suppression device with the inductor as a main body between the high-voltage cable shielding layer and the vehicle body grounding wire;
a6, utilizing an installed suppressing device to reduce the overvoltage of the vehicle body in a voltage division mode;
a7, simulating the overvoltage of the vehicle body of the installation suppression device;
a8, comparing the simulation result with original vehicle body simulation data, confirming the effectiveness of the suppression device, and selecting an inductance value interval of the suppression device;
a9, designing a suppression device object according to the inductance value interval, and completing the design of the suppression device, wherein the main body of the suppression device is arranged as a spiral ring inductor with a spiral coil wound around a magnetic core, and the inductance expression of the spiral coil is as follows:
wherein L is 0 Represents the inductance of the spiral coil, mu 0 Represents vacuum permeability, mu r Indicating the relative magnetic permeability of the magnetic core, N indicating the number of turns of the spiral coil, h indicating the height of the magnetic core, r 1 Represents the outer radius of the magnetic core, r 2 Indicating the core inner radius.
The present invention is further described below.
In this embodiment, the method for suppressing the influence of the overvoltage starts from three major elements of electromagnetic compatibility, and can be divided into reducing the interference source, suppressing the propagation path and improving the immunity of the sensitive device. However, from the viewpoint of the versatility of the suppression means and the distribution of the high-voltage cables in the motor train unit, the suppression propagation path is more easily applied to practical engineering. Through the explanation, the overvoltage is coupled to the shielding layer through the distributed capacitance between the high-voltage cable core wire and the shielding layer, and then is transmitted to the vehicle body, the high-voltage cable shielding layers of different motor train units are connected with the vehicle body, and a suppression means is developed from the path, so that the suppression means has universality.
In this embodiment, the operating overvoltage frequency is typically distributed between several hundred kHz and 2MHz, so it is considered to use an inductor-based suppression device to suppress propagation of the overvoltage. As shown in fig. 3, the working principle of the device can be equivalent to a series voltage divider, so that the overvoltage voltage division of the vehicle body and the grounding system is reduced.
In the present embodiment, the impedance of the suppressing device is an important parameter in voltage division, and in order to significantly reduce the overvoltage component on the vehicle body, the impedance of the suppressing device should be equal to or greater than the impedance of the vehicle body and the grounding system, i.e. Z L ≥Z C +Z G Wherein Z is L To suppress device impedance, Z C Z is the impedance of the vehicle body G Is the ground system impedance.
In this embodiment, the vehicle body impedance is divided into two parts, namely, a quadrilateral network of the vehicle body impedance can be constructed, as shown in fig. 4, the vehicle body transverse direction refers to the direction along the end walls at two sides of the train, and the vehicle body longitudinal direction refers to the direction from the roof to the underframe of the train.
In this embodiment, the equivalent impedance of the grounding system is established according to the distribution position of the grounding shaft ends of the standard motor train unit, as shown in fig. 5.
In this embodiment, taking the impedance of each part of the standard motor train unit as an example, the equivalent impedance of the whole vehicle is built, as shown in fig. 6, and the overvoltage frequency is recorded to be 0.5-1.5MHz, and the overvoltage frequency band sweep is performed on the impedance of the whole vehicle to obtain Z C +Z G And (3) about 47 to 143 omega, and substituting the corresponding frequency to obtain L is more than or equal to 15 mu H.
In this embodiment, as shown in fig. 7, cn is the distributed capacitance between each section of core wire and the shielding layer, rn and Ln are the equivalent impedance of the vehicle body and the grounding system, the distributed capacitance CT also exists between the contact net and the vehicle body, and when the inductance of the introduced suppression device is sufficiently large, the operation overvoltage will be forced to bleed through the distributed capacitance between the contact net and the vehicle body, and the roof may be broken down.
In the embodiment, an irregular capacitor approximation algorithm in the electric power system overvoltage measurement is cited, the overhead contact line is regarded as an infinitely long straight wire, the end effect and the sag effect of the overhead contact line are ignored, and the distributed capacitance between the overhead contact line and the vehicle body is calculated. Since the radius of the contact net is r, it can be regarded as a thin strip of width 2r and length l. Taking the length of the car body as a and the width as b. A plane is taken between the two polar plates and is parallel to the polar plates, the distance between the plane and the polar plates is dz, and the plane area is S. The capacitance of the unit small plate capacitor with the interval dz is calculated by a plate capacitance calculation formula:
dC＝εS/dz
the distributed capacitance between the catenary and the car body can be considered as a series connection of a plurality of small plate capacitors:
wherein, the change range of z is from 0 to h, and the integral area is shown in fig. 8, and is the area in the connecting line of the vertex corresponding to the thin belt and the vehicle body:
in this embodiment, the characteristic parameters are brought into the standard motor train unit to obtain the distributed capacitance C S 81pF, Z L +Z C +Z G <<Z Cs Therefore, take Z L ≤Z Cs And/10, i.e., L.ltoreq.125.mu.H, so that 15.mu.H.ltoreq.L.ltoreq.125.mu.H.
In this embodiment, the inductance of the suppression device is sequentially set to 20 μh, 50 μh, and 100 μh, and the suppression device is placed between the 3-6 vehicle high voltage cable shielding layer and the vehicle body ground line, and the overall system is subjected to overvoltage simulation, as shown in fig. 9, by the simulation circuit, and the respective vehicle body and shaft end overvoltage simulation results are shown in table 1 and table 2, where table 1 is the simulation result of the operation overvoltage of the vehicle body at 1-4 vehicle shaft ends for different inductance of the suppression device, and table 2 is the simulation result of the operation overvoltage at 1-4 vehicle shaft ends (each representative shaft end is taken for different inductance of the suppression device).
TABLE 1
| 0μH | | 50μH | 100μH | ||
| 1 vehicle | 3.01kV | 2.71kV | 2.08kV | 1.51kV | |
| 2-vehicle | 4.86kV | 3.57kV | 2.74kV | 1.98kV | |
| 3-vehicle | 3.95kV | 2.88kV | 2.19kV | 1.58kV | |
| 4-vehicle | 3.01kV | 1.28kV | 1.18kV | 0.37kV |
TABLE 2
| 0μH | 20μH | 50μH | 100μH | |
| 1-vehicle 1-axle | 1.54kV | 1.13kV | 0.87kV | 0.63kV |
| 2 car 4 axle | 0.85kV | 0.65kV | 0.51kV | 0.37kV |
| 3 |
0.92kV | 0.53kV | 0.32kV | 0.20kV |
| 3 |
2.46kV | 1.82kV | 1.41kV | 1.03kV |
| 4 |
1.73kV | 1.11kV | 0.80kV | 0.57kV |
In the embodiment, simulation data show that the suppression device has a suppression effect on both the vehicle body operation overvoltage and the shaft end overvoltage.
In this embodiment, the vehicle body overvoltage suppression device is designed next.
In this embodiment, the suppression device inductance is taken to be 50-100 μh according to the calculation result of the suppression device inductance. In practical applications, the inductor is typically formed by winding a wire around a cylindrical conductor, with a loss resistance R L And distributed capacitance C L The equivalent circuit diagram is shown in fig. 10.
In the present embodiment, because of the distributed capacitance C L The suppressing means has a self-resonant frequency. In order to enable the suppression device to normally operate in the overvoltage frequency range, the suppression device self-resonates at a frequency f>>The overvoltage frequency F is set to be 2MHz for the convenience of calculation, and the distributed capacitance C can be calculated by an equivalent circuit L <<127pF。
In this embodiment, the main body of the suppression device is set as a spiral loop inductor in which a spiral coil is wound around a magnetic core, and the formula is calculated according to the spiral coil inductance:
wherein r is 1 For the outer radius of the magnetic core, r 2 Is the inner radius of the magnetic core, h is the height of the magnetic core, mu 0 Is vacuum permeability, mu r For the magnetic core relative permeability, N is the number of coil turns.
In this embodiment, r is 1 Set to 40mm, r 2 Set to 25mm, h set to 50mm, N set to 20 turns, known μ 0 ＝4π×10 -7 H/m, can give 26.6<μ r <53.2。
In this example, the peak current through the 100 μh coil at the overvoltage time is about 97A, the peak voltage is about 18.54kV, the peak current through the 50 μh coil is about 94A, the peak voltage is about 13.25kV, and the peak current is calculated by the spiral loop magnetic flux formula:
wherein I is 0 Is the current through the coil.
In this embodiment, at the overvoltage time, the maximum magnetic induction intensity of the magnetic core passing through the magnetic core is 0.31T-0.63T.
The main design of the suppression device is shown in fig. 11, and the main parameters are shown in table 3.
TABLE 3 Table 3
In this embodiment, modeling is performed in simulation software, and the relative magnetic permeability of the magnetic core is set to 30 and 50, so as to obtain inductance corresponding to the relative magnetic permeability, as shown in fig. 12.
In this example, after the magnetic core material is selected by the relative permeability and the maximum magnetic flux, it is determined that the iron powder core material having a saturation induction of 1.4T is used as the magnetic core, and the winding is required to withstand a transient overvoltage of 20 kV.
In this example, the following experimental verification was performed on the suppression device parameters.
In this embodiment, an iron powder core is used as the magnetic core material, and the effective relative permeability of the iron powder core decreases with increasing frequency, as shown in fig. 13.
In this embodiment, the relative permeability decays from 57 to 35 in the overvoltage distribution band. The example of the inhibitor is shown in FIG. 14, the main parameters are shown in Table 4, and Table 4 shows the example of the main parameters.
TABLE 4 Table 4
In this example, the suppression device was swept from 100kHz to 10MHz using an impedance analyzer TH2851-030, with a voltage of 500mV, the field layout shown in FIG. 15, and the impedance profile shown in FIG. 16.
In this example, it is known from the impedance curve that the reduction of the real inductance of the suppression device from 112 μH to 67 μH within 100kHz-2MHz is consistent with theoretical predictions. The resonance point is 6.8MHz, and the resonance formula is adopted
Can divide electric capacity C L =9.4 pF, and all of the above characteristic parameters satisfy the theoretical design.
The invention starts from the high-voltage side to the operation overvoltage of the motor train unit through the propagation path, and the suppression device which takes the inductor as a main body is connected in series between the high-voltage cable shielding layer and the ground wire of the vehicle body, so that the grounding mode is changed from direct grounding to inductive grounding, and the transverse overvoltage and shaft end overvoltage of the vehicle body can be effectively suppressed. The invention takes a spiral coil wound magnetic core as a main body of the suppression device, coils are wound according to theoretical calculated parameters, magnetic core materials are arranged, parameters are swept through an impedance analyzer, and the result is matched with theoretical calculation.
Claims (6)
1. A method for suppressing an overvoltage high-voltage side of a motor train unit operation, comprising the steps of:
s1, closing a circuit breaker;
s2, generating overvoltage in the high-voltage cable core wire;
s3, coupling the generated overvoltage to the shielding layer through a distributed capacitor of the high-voltage cable core wire and the shielding layer;
s4, transmitting an overvoltage signal on the shielding layer to the vehicle body through a grounding wire between the shielding layer and the vehicle body;
s5, a suppression device is connected in series on the grounding line, and the suppression device is utilized to share an overvoltage signal, so that suppression of the operation overvoltage high-voltage side of the motor train unit is completed, wherein the suppression device and the vehicle body form a series connection relationship, and the impedance of the suppression device is larger than that of the vehicle body.
2. The method for suppressing an overvoltage high voltage side of a motor train unit operation according to claim 1, wherein the method for designing the suppressing device is as follows:
a1, collecting vehicle body overvoltage data;
a2, establishing a simulation model, and optimizing the simulation model by utilizing the collected overvoltage data;
a3, respectively obtaining parameters of the vehicle body, the impedance of the grounding system and distribution parameters of the contact net to the vehicle body by using the optimized simulation model;
a4, setting the inductance of the suppression device according to the result obtained in the step A3;
a5, based on the suppression device with the inductance value set, installing the suppression device with the inductor as a main body between the high-voltage cable shielding layer and the vehicle body grounding wire;
a6, utilizing an installed suppressing device to reduce the overvoltage of the vehicle body in a voltage division mode;
a7, simulating the overvoltage of the vehicle body of the installation suppression device;
a8, comparing the simulation result with original vehicle body simulation data, confirming the effectiveness of the suppression device, and selecting an inductance value interval of the suppression device;
and A9, designing a real object of the suppression device according to the inductance value interval, and completing the design of the suppression device.
3. The method for suppressing an overvoltage high voltage side of a motor train unit operation according to claim 2, wherein an expression of impedance of the suppressing means is as follows:
Z L ≥Z C +Z G
wherein Z is L Represents the impedance of the suppression device, Z C Represents the impedance of the vehicle body, Z G Representing the ground system impedance.
4. A method for suppressing an overvoltage high voltage side of a motor train unit operation according to claim 3, wherein the step A4 includes the steps of:
a401, calculating the distributed capacitance between the contact net and the car body according to the result obtained in the step A3;
a402, obtaining the inductance of the suppression device according to the distributed capacitance and the impedance of the suppression device.
5. The method for suppressing an overvoltage high voltage side of a motor train unit operation according to claim 4, wherein the expression of the distributed capacitance is as follows:
wherein C represents the capacitance of a capacitor having a pitch dz, ε represents the integral of dz from 0 to h, ε represents the air dielectric constant, S represents the planar area between two plates of the distributed capacitance, dz represents the micro-element distance between the overhead contact line and the vehicle body, r represents the radius of the overhead contact line, h represents the overhead contact line-to-roof pitch, b represents the width of the vehicle body, a represents the length of the vehicle body, and l represents the length of the overhead contact line.
6. The method for suppressing an overvoltage high side of a motor train unit operation according to claim 5, wherein a main body of the suppressing device is provided as a spiral wound inductor of a spiral coil wound around a magnetic core, wherein an inductance expression of the spiral coil is as follows:
wherein L is 0 Represents the inductance of the spiral coil, mu 0 Represents vacuum permeability, mu r Indicating the relative magnetic permeability of the magnetic core, N indicating the number of turns of the spiral coil, h indicating the height of the magnetic core, r 1 Represents the outer radius of the magnetic core, r 2 Indicating the core inner radius.
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