Parameter calibration method, RC circuit, traction power supply system and train

Abstract

This disclosure provides a parameter calibration method, a resistive-capacitive circuit, a traction power supply system, and a train, relating to the field of rail vehicle technology. The parameter calibration method includes: performing spectral analysis on the overvoltage signal of an on-board voltage transformer to obtain multiple oscillation frequency components of the overvoltage signal; based on the suppression effect of the first resistive-capacitive sub-circuit on the multiple oscillation frequency components in the overvoltage signal, determining a first constraint condition between the first resistance value and the first capacitance value of the first resistive-capacitive sub-circuit through network function analysis; based on the first constraint condition, analyzing the influence of the first resistive-capacitive sub-circuit on the electrical characteristics of the on-board voltage transformer to determine the first resistance value and the first capacitance value; and based on the impedance suppression effect of the second resistive-capacitive sub-circuit, determining the second resistance value and the second capacitance value of the second resistive-capacitive sub-circuit through equivalent impedance analysis.

Description

Technical Field

[0001] This disclosure relates to the field of rail vehicle technology, and more specifically, to a parameter calibration method, a resistor-capacitor circuit, a traction power supply system, and a train. Background Technology

[0002] Currently, with the rapid development of high-speed railways in my country, the safety and stability of the power supply system for high-speed trains have become key factors affecting train operating efficiency. Among these, the on-board voltage transformer, as a core measuring component in the traction power supply system of high-speed trains, undertakes important functions such as voltage monitoring, energy metering, relay protection, and fault diagnosis, and is crucial to the safe operation of trains. However, during high-speed train operation, the primary side of the on-board voltage transformer is often affected by factors such as ferroresonance, transient overvoltage, and sudden load changes, which can easily lead to serious electrical faults and affect the stability of the power supply system.

[0003] Current technical means mainly use ferroresonant suppressors and damping resistors to suppress overvoltage on the primary side of on-board voltage transformers. However, due to the complex operating environment of EMUs, there are many factors that affect the overvoltage on the primary side of on-board voltage transformers. The above-mentioned technical means cannot suppress resonant overvoltage stably and reliably while ensuring measurement accuracy, and are difficult to adapt to different operating conditions. Summary of the Invention

[0004] In view of this, this disclosure provides a parameter calibration method, a resistor-capacitor circuit, a traction power supply system, and a train.

[0005] One aspect of this disclosure provides a parameter calibration method for an overvoltage suppression-based RC circuit, used to determine the circuit parameters of an on-board voltage transformer's RC circuit. The RC circuit includes a first RC sub-circuit connected in series with the primary side of the on-board voltage transformer and a second RC sub-circuit connected in parallel with the primary side of the on-board voltage transformer. The method includes: performing spectral analysis on the overvoltage signal of the on-board voltage transformer to obtain multiple oscillation frequency components of the overvoltage signal; based on the suppression effect of the first RC sub-circuit on the multiple oscillation frequency components in the overvoltage signal, determining a first constraint condition between a first resistance value and a first capacitance value of the first RC sub-circuit through network function analysis; based on the first constraint condition, analyzing the influence of the first RC sub-circuit on the electrical characteristics of the on-board voltage transformer to determine the first resistance value and the first capacitance value; and based on the impedance suppression effect of the second RC sub-circuit, determining a second resistance value and a second capacitance value of the second RC sub-circuit through equivalent impedance analysis.

[0006] According to embodiments of this disclosure, spectral analysis is performed on the overvoltage signal of an on-board voltage transformer to obtain multiple oscillation frequency components of the overvoltage signal, including: performing spectral analysis on the overvoltage signal of the on-board voltage transformer to obtain multiple harmonic frequencies of the overvoltage signal in the frequency domain; selecting harmonic frequencies less than or equal to one-third of the operating frequency of the on-board voltage transformer from the multiple harmonic frequencies to determine multiple oscillation frequencies, thereby obtaining multiple oscillation frequency components.

[0007] According to embodiments of this disclosure, based on the suppression effect of the first RC sub-circuit on multiple oscillation frequency components in the overvoltage signal, a first constraint condition between the first resistance value and the first capacitance value of the first RC sub-circuit is determined through network function analysis. This includes: for any target frequency component among the multiple oscillation frequency components, based on the suppression effect of the first RC sub-circuit on the target frequency component in the overvoltage signal, determining the relationship between the first resistance value, the first capacitance value, and the attenuation amount of the target frequency component in the overvoltage signal through network function analysis; based on the relationship between the first resistance value, the first capacitance value, and the attenuation amount, obtaining the first initial constraint condition between the first resistance value and the first capacitance value by inverting according to the constraint range of the attenuation amount; and obtaining the first constraint condition between the first resistance value and the first capacitance value based on multiple first initial constraint conditions.

[0008] According to embodiments of this disclosure, the attenuation amount is constrained to be less than or equal to a first preset attenuation value.

[0009] According to an embodiment of this disclosure, when the attenuation of the second frequency component of the overvoltage signal of the vehicle-mounted voltage transformer is less than a second preset attenuation value, the second resistance value and the second capacitance value are adjusted with the goal of increasing the equivalent impedance of the second RC sub-circuit and the vehicle-mounted voltage transformer. The second frequency component is determined by the operating frequency of the vehicle-mounted voltage transformer.

[0010] According to embodiments of this disclosure, based on a first constraint condition, the influence of the first RC sub-circuit on the electrical characteristics of the vehicle-mounted voltage transformer is analyzed to determine the first resistance value and the first capacitance value, including: obtaining the operating frequency, equivalent inductance value, and equivalent resistance value of the vehicle-mounted voltage transformer; based on the first capacitance value and equivalent inductance value, analyzing the resonant characteristics of the first overall circuit to determine the range of the first capacitance value, wherein the first overall circuit is composed of the first RC sub-circuit and the vehicle-mounted voltage transformer; based on the resistance voltage division analysis of the vehicle-mounted voltage transformer and the first RC sub-circuit, obtaining the range of the first resistance value according to the first resistance value constraint condition, wherein the first resistance value constraint condition is determined based on the equivalent resistance value; and based on the first constraint condition, the range of the first capacitance value, and the range of the first resistance value, determining the first resistance value and the first capacitance value.

[0011] According to an embodiment of this disclosure, based on the first capacitance value and the equivalent inductance value, the range of the first capacitance value is determined by analyzing the resonant characteristics of the first overall circuit. The first overall circuit is composed of a first RC sub-circuit and an on-board voltage transformer. The method includes: based on the relationship between the first capacitance value, the equivalent inductance value and the resonant frequency of the first overall circuit, the range of the first capacitance value is obtained by inversion according to the constraint condition that the resonant frequency is less than the operating frequency.

[0012] According to embodiments of this disclosure, based on the impedance suppression effect of the second RC sub-circuit, the second resistance value and the second capacitance value of the second RC sub-circuit are determined through equivalent impedance analysis, including: obtaining the first equivalent impedance, first equivalent phase, and grounding resistance of the on-board voltage transformer, the second equivalent impedance of the second overall circuit, and the third equivalent impedance and third equivalent phase of the third overall circuit, wherein the second overall circuit is composed of the first RC sub-circuit and the second RC sub-circuit, and the third overall circuit is composed of the first RC sub-circuit, the second RC sub-circuit, and the on-board voltage transformer; based on the first equivalent impedance and the second equivalent impedance, and according to the impedance matching analysis of the on-board voltage transformer and the second overall circuit, a second constraint between the second resistance value and the second capacitance value is determined. The conditions are as follows: Based on the first and third equivalent impedances, and according to the impedance matching analysis of the on-board voltage transformer and the third overall circuit, a third constraint condition between the second resistance value and the second capacitance value is determined; Based on the first and third equivalent phases, and according to the phase matching analysis of the on-board voltage transformer and the third overall circuit, a fourth constraint condition between the second resistance value and the second capacitance value is determined; Based on the grounding potential analysis of the on-board voltage transformer, and according to the second resistance value constraint condition, the range of the second resistance value is determined, wherein the second resistance value constraint condition is determined based on the grounding resistance; Based on the second, third, and fourth constraint conditions, and the range of the second resistance value, the second resistance value and the second capacitance value are determined.

[0013] According to embodiments of this disclosure, based on a first equivalent impedance and a second equivalent impedance, and based on impedance matching analysis of the vehicle-mounted voltage transformer and the second overall circuit, a second constraint condition between a second resistance value and a second capacitance value is determined, including: based on the relationship between the second resistance value, the second capacitance value, and the second equivalent impedance, and based on a third resistance constraint condition of the modulus of the second equivalent impedance, the second constraint condition between the second resistance value and the second capacitance value is obtained by inversion, wherein the third resistance constraint condition is determined by the modulus of the first equivalent impedance.

[0014] According to embodiments of this disclosure, based on the first equivalent impedance and the third equivalent impedance, and based on the impedance matching analysis of the vehicle-mounted voltage transformer and the third overall circuit, a third constraint condition between the second resistance value and the second capacitance value is determined, including: based on the relationship between the second resistance value, the second capacitance value, and the third equivalent impedance, and based on the first interval constraint condition of the modulus of the third equivalent impedance, the third constraint condition between the second resistance value and the second capacitance value is obtained, wherein the first interval constraint condition is determined by the modulus of the first equivalent impedance.

[0015] According to embodiments of this disclosure, based on a first equivalent phase and a third equivalent phase, and based on phase matching analysis of the on-board voltage transformer and the third overall circuit, a fourth constraint condition between the second resistance value and the second capacitance value is determined, including: based on the relationship between the second resistance value, the second capacitance value, and the third equivalent phase, and based on the second interval constraint condition of the third equivalent phase, a fourth constraint condition between the second resistance value and the second capacitance value is obtained, wherein the second interval constraint condition is determined by the first equivalent phase.

[0016] Another aspect of this disclosure provides a resistor-capacitor circuit whose circuit parameters are determined using the parameter calibration method described above.

[0017] Another aspect of this disclosure provides a traction power supply system, including an on-board voltage transformer and a resistor-capacitor circuit as described above.

[0018] Another aspect of this disclosure provides a train, including a car body structure and a traction power supply system as described above.

[0019] According to embodiments of this disclosure, an RC circuit can be designed by analyzing the frequency attenuation characteristics of overvoltage and the electrical characteristics of the circuit, and then applied to the on-board voltage transformer. This can suppress the impact of overvoltage on the on-board voltage transformer, improve voltage measurement accuracy, avoid relay protection malfunctions, reduce the probability of winding rupture accidents, and provide important protection for the safe operation of the EMU. Attached Figure Description

[0020] The above and other objects, features and advantages of this disclosure will become clearer from the following description of embodiments with reference to the accompanying drawings, in which:

[0021] Figure 1 A schematic diagram of a circuit system including an RC loop according to an embodiment of the present disclosure is shown.

[0022] Figure 2 A flowchart illustrating a parameter calibration method for an overvoltage suppression-based RC circuit according to an embodiment of the present disclosure is shown schematically.

[0023] Figure 3A flowchart illustrating a parameter calibration method for an overvoltage suppression-based RC circuit according to another embodiment of the present disclosure is shown schematically.

[0024] Figure 4 A schematic diagram of a traction power supply system according to an embodiment of the present disclosure is shown.

[0025] Figure 5 A schematic diagram of the structure of a train according to an embodiment of the present disclosure is shown. Detailed Implementation

[0026] The embodiments of the present disclosure will now be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the disclosure. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of the present disclosure for ease of explanation. However, it will be apparent that one or more embodiments may be practiced without these specific details. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concepts of the present disclosure.

[0027] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0028] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0029] When using expressions such as "at least one of A, B and C", they should generally be interpreted in accordance with the meaning that is commonly understood by those skilled in the art (e.g., "a system having at least one of A, B and C" should include, but is not limited to, a system having A alone, a system having B alone, a system having C alone, a system having A and B, a system having A and C, a system having B and C, and / or a system having A, B and C, etc.).

[0030] Figure 1 A schematic diagram of a circuit system including an RC circuit according to an embodiment of the present disclosure is shown.

[0031] like Figure 1 As shown, the circuit system includes a power supply 101, a first RC sub-circuit 102, a second RC sub-circuit 103, and an on-board voltage transformer 104.

[0032] The power supply 101 is electrically connected to the first RC sub-circuit 102, the second RC sub-circuit 103 and the vehicle voltage transformer 104 to provide electrical energy.

[0033] The first RC sub-circuit 102 includes a first resistor 1021 and a first capacitor 1022 connected in parallel. The first RC sub-circuit 102 is connected in series with the on-board voltage transformer 104 and is used to suppress the oscillation frequency in the traction power supply system.

[0034] The second RC sub-circuit 103 includes a second resistor 1031 and a second capacitor 1032 connected in parallel. The second RC sub-circuit 103 is connected in parallel with the vehicle voltage transformer 104 to reduce the equivalent input impedance change introduced by the first RC sub-circuit 102 and avoid sudden changes in system impedance.

[0035] The on-board voltage transformer 104 is used to measure relevant electrical parameters of the traction power supply system in the train.

[0036] In embodiments of this disclosure, the first resistor and the first capacitor in the first RC sub-circuit can be connected in series, and the second resistor and the second capacitor in the second RC sub-circuit can also be connected in series. The first RC sub-circuit may further include two resistors and two capacitors to form a second-order RC circuit.

[0037] In the embodiments of this disclosure, multiple different resistors and capacitors can be set in the first and second RC sub-circuits according to different circuit connection methods for application in vehicle-mounted voltage transformers, thereby achieving different circuit system characteristics. In the embodiments of this disclosure, for the multiple resistors and capacitors in the first and second RC sub-circuits, parameter calibration can be performed on the resistance values ​​of the multiple resistors and the capacitance values ​​of the multiple capacitors to obtain multiple resistors with specific resistance values ​​and multiple capacitors with specific capacitance values ​​for application in vehicle-mounted voltage transformers, thereby achieving different circuit system characteristics.

[0038] Figure 2 A flowchart illustrating a parameter calibration method for an overvoltage suppression-based RC circuit according to an embodiment of the present disclosure is shown.

[0039] like Figure 2 As shown, the method includes operations S210~S240.

[0040] In operation S210, the overvoltage signal of the vehicle-mounted voltage transformer is subjected to spectrum analysis to obtain multiple oscillation frequency components of the overvoltage signal.

[0041] Spectrum analysis is a signal processing technique that decomposes complex signals into different frequency components and analyzes the amplitude and phase of these components. When all frequency components of a signal are integer multiples of a certain frequency, that frequency is called the fundamental frequency, corresponding to the sine wave component with the longest period and largest amplitude. Its value is equal to the periodicity of the lowest frequency component in the signal's spectrum. Harmonic frequencies, on the other hand, are frequencies that are integer multiples of the fundamental frequency. For example, when the fundamental frequency is 5 Hz, the harmonic frequencies are 5 Hz, 10 Hz, 15 Hz, 20 Hz, 25 Hz, and so on.

[0042] In the embodiments of this disclosure, the methods for performing spectral analysis on overvoltage signals include, but are not limited to: Fourier transform, fast Fourier transform, periodogram method, multi-signal classification method, short-time Fourier transform, and wavelet transform.

[0043] For example, Fourier transform can be used to perform spectral analysis on overvoltage signals. The expression for converting the overvoltage signal from the time domain to the frequency domain is:

[0044] (1)

[0045] in The DC component, Let ω be the amplitude of the nth harmonic, and ω be the fundamental angular frequency. Let t be the phase of the nth harmonic, and t be time.

[0046] Expanding formula (1) yields:

[0047] (2)

[0048] in, For the real part of the harmonic component, This represents the imaginary part of the harmonic components;

[0049] From the orthogonality of trigonometric functions, we can obtain the following:

[0050] (3)

[0051] Where T is the time period of the signal.

[0052] Using sampled value notation, it can be transformed into:

[0053] (4)

[0054] Where N is the number of sampling points in one cycle when the signal frequency is the fundamental frequency.

[0055] Further analysis reveals that the amplitude of the harmonics is:

[0056] (5)

[0057] The phase of the harmonic is:

[0058] (6)

[0059] By analyzing the harmonic components, multiple oscillation frequency components of the overvoltage signal are obtained.

[0060] In operation S220, based on the suppression effect of the first RC sub-circuit on multiple oscillation frequency components in the overvoltage signal, the first constraint condition between the first resistance value and the first capacitance value of the first RC sub-circuit is determined through network function analysis.

[0061] A network function is a function that represents the excitation-response relationship of a linear electrical network. When an excitation is applied to a port of a circuit that does not have independent power sources internally, the ratio of the Laplace transform image function of a zero-state response under this excitation to the image function of the excitation is called the network function.

[0062] In embodiments of this disclosure, the network function of the first RC sub-loop can be expressed as:

[0063] (7)

[0064] Among them, R 01 C is the first resistance value. 01 This is the first capacitance value. ω is the angular frequency.

[0065] For a specific angular frequency, the first constraint condition between the first resistance value and the first capacitance value can be determined by constraining the modulus of the network function.

[0066] In operation S230, based on the first constraint condition, the influence of the first RC sub-circuit on the electrical characteristics of the vehicle voltage transformer is analyzed to determine the first resistance value and the first capacitance value.

[0067] A first RC sub-circuit is connected in series at the front end of the primary side of the vehicle voltage transformer. The newly added first resistor and first capacitor will affect the electrical characteristics of the vehicle voltage transformer. By analyzing the changed electrical characteristics, the optimal values ​​of the first resistor and first capacitor can be determined based on the constraints of the electrical characteristics.

[0068] In operation S240, based on the impedance suppression effect of the second RC sub-circuit, the second resistance value and the second capacitance value of the second RC sub-circuit are determined through equivalent impedance analysis.

[0069] Connecting a first RC sub-circuit in series at the primary side of an on-board voltage transformer will cause a sudden impedance change on the primary side, affecting the stable operation of related equipment and the accuracy of voltage measurement. Connecting a second RC sub-circuit in parallel across the on-board voltage transformer can optimize impedance matching. Based on specific impedance matching requirements, the second resistance value and the second capacitance value of the second RC sub-circuit can be determined.

[0070] Through the embodiments of this disclosure, an RC circuit can be designed by analyzing the frequency attenuation characteristics of overvoltage and the electrical characteristics of the circuit, and applied to the on-board voltage transformer. This can suppress the impact of overvoltage on the on-board voltage transformer, improve voltage measurement accuracy, avoid relay protection malfunctions, reduce the probability of winding rupture accidents, and provide important protection for the safe operation of EMU.

[0071] According to embodiments of this disclosure, spectral analysis is performed on the overvoltage signal of the vehicle-mounted voltage transformer to obtain multiple oscillation frequency components of the overvoltage signal, including:

[0072] Spectral analysis is performed on the overvoltage signal of the vehicle-mounted voltage transformer to obtain multiple harmonic frequencies of the overvoltage signal in the frequency domain. Among the multiple harmonic frequencies, harmonic frequencies less than or equal to one-third of the operating frequency of the vehicle-mounted voltage transformer are selected to determine multiple oscillation frequencies and obtain multiple oscillation frequency components.

[0073] In the embodiments of this disclosure, the operating frequency of the vehicle-mounted voltage transformer is 50 Hz. Harmonic frequencies less than or equal to one-third of the operating frequency of the vehicle-mounted voltage transformer can be determined using a spectrum analyzer or an oscilloscope.

[0074] For example, a spectrum analyzer can be used to determine the harmonic frequencies of an overvoltage signal as 5 Hz, 10 Hz, 15 Hz, 20 Hz, 25 Hz, etc. Since 5 Hz, 10 Hz, and 15 Hz are less than one-third of the operating frequency, and 20 Hz and 25 Hz are greater than one-third of the operating frequency, 5 Hz, 10 Hz, and 15 Hz can be identified as multiple oscillation frequencies to obtain multiple oscillation frequency components of the overvoltage signal.

[0075] In the embodiments of this disclosure, the common ferroresonant frequency range in vehicle-mounted voltage transformers is one-third of the power frequency and below. During the operation of the EMU, ferroresonant frequency can easily cause resonant overvoltage, which can saturate the magnetic core of the vehicle-mounted voltage transformer, leading to voltage measurement errors and even causing severe distortion of the output voltage. This can prevent the protection device from correctly identifying the fault type, which may result in false tripping or failure to operate, affecting the safety and reliability of the EMU.

[0076] Through the embodiments of this disclosure, common ferromagnetic resonant frequency components in overvoltage signals can be obtained, providing a basis for suppressing common ferromagnetic resonant frequency components in subsequent overvoltage signals.

[0077] According to embodiments of this disclosure, based on the suppression effect of the first RC sub-circuit on multiple oscillation frequency components in the overvoltage signal, a first constraint condition between the first resistance value and the first capacitance value of the first RC sub-circuit is determined through network function analysis, including:

[0078] For any target frequency component among multiple oscillation frequency components, based on the suppression effect of the first RC sub-circuit on the target frequency component in the overvoltage signal, the relationship between the first resistance value, the first capacitance value, and the attenuation of the target frequency component in the overvoltage signal is determined through network function analysis; based on the relationship between the first resistance value, the first capacitance value, and the attenuation, the first initial constraint condition between the first resistance value and the first capacitance value is obtained by inverting according to the constraint range of the attenuation; based on multiple first initial constraint conditions, the first constraint condition between the first resistance value and the first capacitance value is obtained.

[0079] In embodiments of this disclosure, the attenuation amount in the overvoltage signal is the modulus of the network function of the first RC sub-loop, which can be expressed as:

[0080] (8)

[0081] Since the first resistance value, the first capacitance value, and the attenuation have a definite relationship according to formula (8), therefore for any one By constraining the attenuation, the first initial constraint conditions between the first resistance value and the first capacitance value can be obtained by inversion.

[0082] For example, if the constraint is that the attenuation of the 5 Hz frequency component in the overvoltage signal by the first RC sub-circuit is 0.6, then by the angular frequency formula:

[0083] (9)

[0084] Where f is the frequency.

[0085] Then you can equal to 0.6 and equal Substituting into formula (8), we can obtain the first initial constraint condition between the first resistance value and the first capacitance value.

[0086] Through the embodiments of this disclosure, the range of values ​​for circuit parameters in the first RC sub-circuit can be determined based on the suppression effect on the target frequency component in the overvoltage signal, thereby obtaining a first RC sub-circuit with better overvoltage suppression effect.

[0087] According to embodiments of this disclosure, the attenuation amount is constrained to be less than or equal to a first preset attenuation value.

[0088] In the embodiments of this disclosure, for the first RC sub-circuit, the attenuation amount corresponding to each frequency component can be set with different constraint ranges. For example, the attenuation amount corresponding to the 5 Hz frequency component of the overvoltage signal can be less than 0.6, the attenuation amount corresponding to the 10 Hz frequency component of the overvoltage signal can be less than 0.7, and the attenuation amount corresponding to the 15 Hz frequency component of the overvoltage signal can be less than 0.8. By constraining the attenuation amounts of the 5 Hz, 10 Hz, and 15 Hz frequency components in the overvoltage signal, more precise constraint conditions for the first resistance value and the first capacitance value can be determined. In the embodiments of this disclosure, the same constraint range can be set for the attenuation amounts corresponding to different frequency components in the overvoltage signal.

[0089] Preferably, the first preset attenuation value is 0.7.

[0090] Figure 3 A flowchart illustrating a parameter calibration method for an overvoltage suppression-based RC circuit according to another embodiment of this disclosure is shown.

[0091] like Figure 3 As shown, the method includes operations S310~S340.

[0092] In operation S310, the overvoltage signal of the vehicle voltage transformer is subjected to spectrum analysis to obtain multiple oscillation frequency components of the overvoltage signal.

[0093] In operation S320, based on the suppression effect of the first RC sub-circuit on multiple oscillation frequency components in the overvoltage signal, the first constraint condition between the first resistance value and the first capacitance value of the first RC sub-circuit is determined through network function analysis.

[0094] In operation S330, based on the first constraint condition, the influence of the first RC sub-circuit on the electrical characteristics of the vehicle voltage transformer is analyzed to determine the first resistance value and the first capacitance value.

[0095] In operation S340, based on the impedance suppression effect of the second RC sub-circuit, the second resistance value and the second capacitance value of the second RC sub-circuit are determined through equivalent impedance analysis.

[0096] In operation S350, when the attenuation of the second frequency component of the overvoltage signal of the vehicle voltage transformer is less than the second preset attenuation value, the second resistance value and the second capacitance value are adjusted with the goal of increasing the equivalent impedance of the second RC sub-circuit and the vehicle voltage transformer. The second frequency component is determined by the operating frequency of the vehicle voltage transformer.

[0097] The operating frequency of the vehicle-mounted voltage transformer is 50 Hz. Therefore, the attenuation of the second frequency component of the overvoltage signal of the vehicle-mounted voltage transformer is the modulus of the network function of the first RC sub-circuit when the target frequency is 50 Hz.

[0098] In embodiments of this disclosure, the second resistance value and the second capacitance value can be increased to increase the equivalent impedance of the second RC sub-circuit and the on-board voltage transformer. By continuously increasing the equivalent impedance of the second RC sub-circuit and the on-board voltage transformer, the condition that the attenuation of the second frequency component of the overvoltage signal is greater than or equal to the second preset attenuation value is met. Preferably, the second preset attenuation value is 0.95.

[0099] Through the embodiments of this disclosure, the measurement accuracy of the vehicle-mounted voltage transformer signal under power frequency conditions can be guaranteed by setting a threshold based on the attenuation value of the overvoltage signal at the operating frequency component.

[0100] According to embodiments of this disclosure, based on a first constraint condition, the influence of the first RC sub-circuit on the electrical characteristics of the vehicle-mounted voltage transformer is analyzed to determine the first resistance value and the first capacitance value, including: obtaining the operating frequency, equivalent inductance value, and equivalent resistance value of the vehicle-mounted voltage transformer; based on the first capacitance value and equivalent inductance value, analyzing the resonant characteristics of the first overall circuit to determine the range of the first capacitance value, wherein the first overall circuit is composed of the first RC sub-circuit and the vehicle-mounted voltage transformer; based on the resistance voltage division analysis of the vehicle-mounted voltage transformer and the first RC sub-circuit, obtaining the range of the first resistance value according to the first resistance value constraint condition, wherein the first resistance value constraint condition is determined based on the equivalent resistance value; and based on the first constraint condition, the range of the first capacitance value, and the range of the first resistance value, determining the first resistance value and the first capacitance value.

[0101] In the embodiments of this disclosure, the equivalent inductance and equivalent resistance values ​​of the vehicle-mounted voltage transformer can be obtained through theoretical calculations or through experimental measurements. For example, the equivalent inductance and equivalent resistance values ​​can be measured using an impedance analyzer.

[0102] Connecting the first RC sub-circuit in series with the vehicle-mounted voltage transformer increases the overall damping of the system, improving low-frequency (less than 50 Hz) oscillations in the original circuit and accelerating overvoltage decay. Simultaneously, due to the voltage division effect of the first resistor on the equivalent resistance of the vehicle-mounted voltage transformer, there is an upper limit to the value of the first resistance. In embodiments of this disclosure, the constraint condition for the first resistance value can be that the first resistance value is less than or equal to ten times the equivalent resistance of the vehicle-mounted voltage transformer.

[0103] Through the embodiments of this disclosure, the specific circuit parameters in the first RC sub-circuit can be determined based on the influence analysis of the first RC sub-circuit on the electrical characteristics of the vehicle voltage transformer, thereby obtaining a first RC sub-circuit with better overvoltage suppression effect.

[0104] According to an embodiment of this disclosure, based on the first capacitance value and the equivalent inductance value, the range of the first capacitance value is determined by analyzing the resonant characteristics of the first overall circuit. The first overall circuit is composed of a first RC sub-circuit and an on-board voltage transformer. The method includes: based on the relationship between the first capacitance value, the equivalent inductance value and the resonant frequency of the first overall circuit, the range of the first capacitance value is obtained by inversion according to the constraint condition that the resonant frequency is less than the operating frequency.

[0105] When the first RC sub-circuit is connected in series with the vehicle-mounted voltage transformer, the entire circuit forms the first integrated circuit. Since this integrated circuit contains both capacitive and inductive elements, a resonant point is generated. The resonant point of a circuit refers to the specific frequency at which, in an AC circuit containing both inductance and capacitance, the total impedance exhibits pure resistance (i.e., inductive reactance and capacitive reactance cancel each other out), and the current and voltage are in phase. If the resonant frequency is near the operating frequency of the vehicle-mounted voltage transformer, this resonant characteristic will affect the normal operation of the transformer; therefore, the range of the resonant frequency needs to be constrained.

[0106] The resonant frequency can be expressed by the following formula:

[0107] (10)

[0108] Among them, L PT C is the equivalent inductance value. 01 This is the first capacitance value.

[0109] Based on the relationship between the first capacitance value, the equivalent inductance value, and the resonant frequency, the range of values ​​for the first capacitance value can be derived from the constraint range of the resonant frequency.

[0110] In the embodiments of this disclosure, the resonant frequency is less than the operating frequency of the vehicle-mounted voltage transformer. By using the constraint that the resonant frequency is less than 50 Hz, the range of values ​​for the first capacitance can be obtained by inversion.

[0111] The embodiments disclosed herein can avoid introducing new resonant points near the operating frequency of the vehicle-mounted voltage transformer, thereby improving the measurement accuracy of the vehicle-mounted voltage transformer at the operating frequency.

[0112] According to embodiments of this disclosure, based on the impedance suppression effect of the second RC sub-circuit, the second resistance value and the second capacitance value of the second RC sub-circuit are determined through equivalent impedance analysis, including: obtaining the first equivalent impedance, first equivalent phase, and grounding resistance of the on-board voltage transformer, the second equivalent impedance of the second overall circuit, and the third equivalent impedance and third equivalent phase of the third overall circuit, wherein the second overall circuit is composed of the first RC sub-circuit and the second RC sub-circuit, and the third overall circuit is composed of the first RC sub-circuit, the second RC sub-circuit, and the on-board voltage transformer; based on the first equivalent impedance and the second equivalent impedance, and according to the impedance matching analysis of the on-board voltage transformer and the second overall circuit, a second constraint between the second resistance value and the second capacitance value is determined. The conditions are as follows: Based on the first and third equivalent impedances, and according to the impedance matching analysis of the on-board voltage transformer and the third overall circuit, a third constraint condition between the second resistance value and the second capacitance value is determined; Based on the first and third equivalent phases, and according to the phase matching analysis of the on-board voltage transformer and the third overall circuit, a fourth constraint condition between the second resistance value and the second capacitance value is determined; Based on the grounding potential analysis of the on-board voltage transformer, and according to the second resistance value constraint condition, the range of the second resistance value is determined, wherein the second resistance value constraint condition is determined based on the grounding resistance; Based on the second, third, and fourth constraint conditions, and the range of the second resistance value, the second resistance value and the second capacitance value are determined.

[0113] In the embodiments of this disclosure, the first equivalent impedance, first equivalent phase, and grounding resistance of the vehicle-mounted voltage transformer, the second equivalent impedance of the second overall circuit, and the third equivalent impedance and third equivalent phase of the third overall circuit can be obtained through theoretical calculation or through experimental measurement. For example, the first, second, and third equivalent impedances can be obtained through digital bridge measurement; the first and third equivalent phases can be obtained through dual-trace oscilloscope measurement; and the grounding resistance can be obtained through clamp-on grounding resistance tester.

[0114] Grounding resistance refers to the total resistance encountered by current as it flows uniformly from the grounding electrode into the earth and diffuses outwards. Due to the influence of grounding resistance, the voltage division ratio of the on-board voltage transformer and the second RC sub-circuit changes, leading to inaccurate output voltage. Therefore, it is necessary to constrain the value of the second resistance based on the grounding resistance value.

[0115] In embodiments of this disclosure, the second resistance constraint condition can be expressed by the following formula:

[0116] (11)

[0117] Among them, R 02 R is the second resistance value. gThis is the resistance value of the grounding resistor.

[0118] Through the embodiments of this disclosure, the impedance surge at the input terminal caused by the first RC sub-circuit connected in series at the front end of the primary side of the vehicle voltage transformer can be reduced based on the impedance suppression effect of the second RC sub-circuit. This suppresses overvoltage surges while improving the measurement accuracy and stability of the vehicle voltage transformer.

[0119] According to embodiments of this disclosure, based on a first equivalent impedance and a second equivalent impedance, and based on impedance matching analysis of the vehicle-mounted voltage transformer and the second overall circuit, a second constraint condition between a second resistance value and a second capacitance value is determined, including: based on the relationship between the second resistance value, the second capacitance value, and the second equivalent impedance, and based on a third resistance constraint condition of the modulus of the second equivalent impedance, the second constraint condition between the second resistance value and the second capacitance value is obtained by inversion, wherein the third resistance constraint condition is determined by the modulus of the first equivalent impedance.

[0120] The equivalent impedance of the second overall circuit can be determined by the following formula:

[0121] (12)

[0122] Among them, R 01 R is the first resistance value. 02 C is the second resistance value. 01 C is the first capacitance value. 02 This is the second capacitance value. ω is the angular frequency.

[0123] In embodiments of this disclosure, the third resistance constraint condition can be expressed by the following formula:

[0124] (13)

[0125] Among them, Z PT The impedance is that of the vehicle-mounted voltage transformer.

[0126] According to embodiments of this disclosure, based on the first equivalent impedance and the third equivalent impedance, and based on the impedance matching analysis of the vehicle-mounted voltage transformer and the third overall circuit, a third constraint condition between the second resistance value and the second capacitance value is determined, including: based on the relationship between the second resistance value, the second capacitance value, and the third equivalent impedance, and based on the first interval constraint condition of the modulus of the third equivalent impedance, the third constraint condition between the second resistance value and the second capacitance value is obtained, wherein the first interval constraint condition is determined by the modulus of the first equivalent impedance.

[0127] The third equivalent impedance can be determined by the following formula:

[0128] (14)

[0129] Among them, Z 01 Z is the impedance of the first RC circuit. 02 The impedance of the second RC circuit is given.

[0130] In embodiments of this disclosure, the first interval constraint condition can be expressed by the following formula:

[0131] (15)

[0132] According to embodiments of this disclosure, based on a first equivalent phase and a third equivalent phase, and based on phase matching analysis of the on-board voltage transformer and the third overall circuit, a fourth constraint condition between the second resistance value and the second capacitance value is determined, including: based on the relationship between the second resistance value, the second capacitance value, and the third equivalent phase, and based on the second interval constraint condition of the third equivalent phase, a fourth constraint condition between the second resistance value and the second capacitance value is obtained, wherein the second interval constraint condition is determined by the first equivalent phase.

[0133] In embodiments of this disclosure, the second interval constraint condition can be expressed by the following formula:

[0134] (16)

[0135] Where, θ total The phase of the third overall circuit, θ PT This refers to the phase of the on-board voltage transformer.

[0136] Figure 4 A schematic diagram of a traction power supply system according to an embodiment of the present disclosure is shown.

[0137] like Figure 4 As shown, 27.5 kV represents the rated AC voltage source of the traction power supply system; the on-board voltage transformer is the main device for measuring the voltage and overvoltage of the vehicle-to-grid system; the surge arrester is also a protection device for system overvoltage, but it has no protection effect against low-frequency oscillating voltage; the main circuit breaker and disconnector are the switching elements of the circuit; the traction transformer is the main power conversion element; the traction converter is the main element for realizing the voltage and current control of the motor; the motor is the main element for controlling the locomotive's running speed. The primary side of the on-board voltage transformer is the winding side that connects the on-board voltage transformer to the voltage source, and the RC circuit is electrically connected to the primary side of the on-board voltage transformer.

[0138] According to the embodiments of this disclosure, the RC circuit in the traction power supply system can be any RC circuit determined by the above parameter calibration method, and for the sake of simplicity, it will not be described in detail here.

[0139] Figure 5 A schematic diagram of the structure of a train according to an embodiment of the present disclosure is shown.

[0140] like Figure 5 As shown, the train 500 may include a car body structure 510 and a traction power supply system 520.

[0141] According to embodiments of this disclosure, the traction power supply system 520 can be any of the traction power supply systems described above, and for simplicity, it will not be described in detail here.

[0142] Those skilled in the art will understand that the features described in the various embodiments of this disclosure can be combined and / or combined in various ways, even if such combinations or combinations are not explicitly described in this disclosure. In particular, the features described in the various embodiments of this disclosure can be combined and / or combined in various ways without departing from the spirit and teachings of this disclosure. All such combinations and / or combinations fall within the scope of this disclosure.

[0143] The embodiments of this disclosure have been described above. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of this disclosure. Although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination. Various substitutions and modifications can be made by those skilled in the art without departing from the scope of this disclosure, and all such substitutions and modifications should fall within the scope of this disclosure.

Claims

1. A parameter calibration method for an RC circuit based on overvoltage suppression, characterized in that, The method is used to determine the circuit parameters of the RC circuit of an on-board voltage transformer. The RC circuit includes a first RC sub-circuit connected in series with the primary side front end of the on-board voltage transformer and a second RC sub-circuit connected in parallel with the primary side front end of the on-board voltage transformer. The method includes: Spectral analysis is performed on the overvoltage signal of the vehicle-mounted voltage transformer to obtain multiple oscillation frequency components of the overvoltage signal; Based on the suppression effect of the first RC sub-circuit on multiple oscillation frequency components in the overvoltage signal, the first constraint condition between the first resistance value and the first capacitance value of the first RC sub-circuit is determined through network function analysis. Based on the first constraint, the influence of the first RC sub-circuit on the electrical characteristics of the vehicle voltage transformer is analyzed to determine the first resistance value and the first capacitance value. Based on the impedance suppression effect of the second RC sub-circuit, the second resistance value and the second capacitance value of the second RC sub-circuit are determined through equivalent impedance analysis.

2. The method according to claim 1, characterized in that, Spectral analysis of the overvoltage signal from the vehicle-mounted voltage transformer yields multiple oscillation frequency components of the overvoltage signal, including: Spectral analysis was performed on the overvoltage signal of the vehicle-mounted voltage transformer to obtain multiple harmonic frequencies of the overvoltage signal in the frequency domain. Among the multiple harmonic frequencies, harmonic frequencies less than or equal to one-third of the operating frequency of the vehicle-mounted voltage transformer are selected to determine multiple oscillation frequencies, thereby obtaining multiple oscillation frequency components.

3. The method according to claim 1, characterized in that, Based on the suppression effect of the first RC sub-circuit on multiple oscillation frequency components in the overvoltage signal, a first constraint condition between the first resistance value and the first capacitance value of the first RC sub-circuit is determined through network function analysis, including: For any one of the multiple oscillation frequency components, based on the suppression effect of the first RC sub-circuit on the target frequency component in the overvoltage signal, the relationship between the first resistance value, the first capacitance value and the attenuation of the target frequency component in the overvoltage signal is determined through network function analysis. Based on the relationship between the first resistance value, the first capacitance value, and the attenuation, the first initial constraint condition between the first resistance value and the first capacitance value is obtained by inverting according to the constraint range of the attenuation. Based on multiple initial constraints, a first constraint condition is obtained between the first resistance value and the first capacitance value.

4. The method according to claim 3, characterized in that, The constraint range for the attenuation amount is that the attenuation amount is less than or equal to a first preset attenuation value.

5. The method according to claim 3, characterized in that, When the attenuation of the second frequency component of the overvoltage signal of the vehicle voltage transformer is less than the second preset attenuation value, the second resistance value and the second capacitance value are adjusted with the goal of increasing the equivalent impedance of the second RC sub-circuit and the vehicle voltage transformer. The second frequency component is determined by the operating frequency of the vehicle voltage transformer.

6. The method according to claim 1, characterized in that, Based on the first constraint, the influence of the first RC sub-circuit on the electrical characteristics of the vehicle-mounted voltage transformer is analyzed to determine the first resistance value and the first capacitance value, including: Obtain the operating frequency, equivalent inductance, and equivalent resistance of the vehicle-mounted voltage transformer; Based on the first capacitance value and the equivalent inductance value, the range of the first capacitance value is determined by analyzing the resonance characteristics of the first overall circuit, wherein the first overall circuit is composed of the first RC sub-circuit and the vehicle voltage transformer. Based on the voltage divider analysis of the on-board voltage transformer and the first RC sub-circuit, the range of the first resistance value is obtained according to the first resistance value constraint condition, wherein the first resistance value constraint condition is determined based on the equivalent resistance value. Based on the first constraint, the range of values ​​for the first capacitor and the range of values ​​for the first resistor, the first resistor value and the first capacitor value are determined.

7. The method according to claim 6, characterized in that, Based on the first capacitance value and the equivalent inductance value, the range of the first capacitance value is determined by analyzing the resonant characteristics of the first overall circuit. The first overall circuit comprises the first RC sub-circuit and the on-board voltage transformer, including: Based on the relationship between the first capacitance value, the equivalent inductance value, and the resonant frequency of the first overall circuit, the range of the first capacitance value is obtained by inversion according to the constraint that the resonant frequency is less than the operating frequency.

8. The method according to claim 1, characterized in that, Based on the impedance suppression effect of the second RC sub-circuit, the second resistance value and the second capacitance value of the second RC sub-circuit are determined through equivalent impedance analysis, including: The first equivalent impedance, first equivalent phase and grounding resistance of the vehicle-mounted voltage transformer, the second equivalent impedance of the second overall circuit, and the third equivalent impedance and third equivalent phase of the third overall circuit are obtained. The second overall circuit is composed of a first RC sub-circuit and a second RC sub-circuit, and the third overall circuit is composed of a first RC sub-circuit, a second RC sub-circuit and the vehicle-mounted voltage transformer. Based on the first equivalent impedance and the second equivalent impedance, and according to the impedance matching analysis of the vehicle voltage transformer and the second overall circuit, the second constraint condition between the second resistance value and the second capacitance value is determined. Based on the first equivalent impedance and the third equivalent impedance, and according to the impedance matching analysis of the vehicle voltage transformer and the third overall circuit, the third constraint condition between the second resistance value and the second capacitance value is determined. Based on the first equivalent phase and the third equivalent phase, and according to the phase matching analysis of the vehicle voltage transformer and the third overall circuit, a fourth constraint condition between the second resistance value and the second capacitance value is determined. Based on the grounding potential analysis of the vehicle-mounted voltage transformer, the range of the second resistance value is determined according to the second resistance value constraint condition, wherein the second resistance value constraint condition is determined based on the grounding resistance; Based on the second constraint, the third constraint, the fourth constraint, and the range of the second resistance value, the second resistance value and the second capacitance value are determined.

9. The method according to claim 8, characterized in that, Based on the first equivalent impedance and the second equivalent impedance, and according to the impedance matching analysis of the on-board voltage transformer and the second overall circuit, a second constraint condition between the second resistance value and the second capacitance value is determined, including: Based on the relationship between the second resistance value, the second capacitance value, and the second equivalent impedance, and according to the third resistance constraint condition of the modulus of the second equivalent impedance, the second constraint condition between the second resistance value and the second capacitance value is obtained by inversion, wherein the third resistance constraint condition is determined by the modulus of the first equivalent impedance.

10. The method according to claim 8, characterized in that, Based on the first equivalent impedance and the third equivalent impedance, and according to the impedance matching analysis of the on-board voltage transformer and the third overall circuit, a third constraint condition between the second resistance value and the second capacitance value is determined, including: Based on the relationship between the second resistance value, the second capacitance value, and the third equivalent impedance, and according to the first interval constraint condition of the modulus of the third equivalent impedance, a third constraint condition between the second resistance value and the second capacitance value is obtained, wherein the first interval constraint condition is determined by the modulus of the first equivalent impedance.

11. The method according to claim 8, characterized in that, Based on the first equivalent phase and the third equivalent phase, and according to the phase matching analysis of the on-board voltage transformer and the third overall circuit, a fourth constraint condition between the second resistance value and the second capacitance value is determined, including: Based on the relationship between the second resistance value, the second capacitance value, and the third equivalent phase, and according to the second interval constraint condition of the third equivalent phase, a fourth constraint condition between the second resistance value and the second capacitance value is obtained, wherein the second interval constraint condition is determined by the first equivalent phase.

12. A resistor-capacitor circuit, characterized in that, The circuit parameters of the RC circuit are determined using the parameter calibration method as described in any one of claims 1 to 11.

13. A traction power supply system, characterized in that, include: Vehicle-mounted voltage transformer; as well as The RC circuit as described in claim 12.

14. A train, characterized in that, include: Vehicle body structure; as well as The traction power supply system as described in claim 13.

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