High-speed train impedance measurement method based on adaptive broadband voltage disturbance

Abstract

This invention discloses a high-speed train impedance measurement method based on adaptive broadband voltage disturbance. It eliminates the influence of frequency overlap effects on impedance measurement during broadband disturbance injection in VSC-type high-speed trains by using odd-even segmented multi-frequency disturbance signals. Simultaneously, it incorporates a disturbance generation device for adaptive broadband disturbance control. Besides generating odd-even segmented multi-frequency voltage disturbances for VSC-type high-speed train impedance measurement, this invention can adaptively adjust the frequency resolution by evaluating the fluctuation level of the impedance amplitude-frequency characteristic curve, improving the measurement accuracy in frequency bands with large impedance curve fluctuations. Furthermore, it can adaptively adjust the disturbance amplitude based on the DC-side voltage fluctuation of the disturbance generation device, preventing excessive disturbances from affecting the normal operation of the system and thus ensuring measurement safety.

Description

Technical Field

[0001] This invention relates to the field of impedance measurement technology for VSC type high-speed trains, and in particular to a high-speed train impedance measurement method based on adaptive wideband voltage disturbance. Background Technology

[0002] High-speed trains are one of the most internationally competitive representative industries in my country's high-end equipment manufacturing sector. Their rapid development is closely related to the increasingly sophisticated high-power power electronic converter technology. Among these, voltage source converters (VSCs) have become the core converter equipment in high-speed train electric traction drive systems due to their advantages such as strong active controllability, fast dynamic response, high energy conversion efficiency, and flexible frequency conversion speed regulation. However, VSCs exhibit constant power characteristics during the power conversion process, causing high-speed trains to exhibit negative resistance characteristics in certain frequency bands, leading to frequent broadband oscillations in the high-speed railway "vehicle-grid" system. Existing research shows that such broadband oscillation problems can be studied using impedance matching analysis. Therefore, accurately obtaining the broadband impedance characteristics of VSC-type high-speed trains is an important way to reveal the broadband oscillation mechanism and is of great significance for ensuring the safe and stable operation of the system.

[0003] Currently, harmonic disturbance injection has become the mainstream method for measuring active systems such as high-speed trains. Based on the number of disturbance frequencies, it can be divided into single-frequency disturbance methods and broadband disturbance methods. The former injects a disturbance of a single frequency into the measured object each time to obtain the impedance characteristics at a specific frequency. However, for broadband impedance measurements, this single-frequency disturbance method requires multiple injections at different frequency points to cover the target measurement frequency band, resulting in long measurement times and asynchronous measurement frequencies. Broadband disturbance methods, on the other hand, can inject disturbances at multiple frequency points into the measured object simultaneously, thus quickly obtaining broadband impedance characteristics. However, existing broadband disturbance methods struggle to accurately control the distribution of broadband harmonics, with some harmonic energy leaking into non-target frequency bands. They also cannot adaptively adjust the amplitude of the broadband harmonic disturbance according to the state of the measurement system to ensure the safety of the measurement system, and cannot adaptively adjust the frequency resolution to improve measurement accuracy in frequency bands with large impedance fluctuations. Summary of the Invention

[0004] The purpose of this invention is to provide a high-speed train impedance measurement method based on adaptive wideband voltage disturbance. It mainly uses odd and even segmented multi-frequency disturbance signals to eliminate the interference of high-speed train frequency overlap effect on wideband impedance measurement. It can adaptively adjust the disturbance frequency resolution of different frequency bands according to the fluctuation of the impedance curve in each frequency band. At the same time, the magnitude of the disturbance can be adaptively adjusted according to the magnitude of DC side voltage fluctuation of the wideband disturbance generation device to prevent the disturbance injection energy from being too large and affecting the safety of the measurement system.

[0005] The technical solution for achieving the objective of this invention is as follows:

[0006] A high-speed train impedance measurement method based on adaptive wideband voltage disturbance involves injecting a voltage disturbance signal using a disturbance generation device. This device includes a multi-winding step-down transformer T1, N back-to-back H-bridge converters, and a wideband coupling transformer T2. The primary winding of T1 is connected to the contact wire at one end via switch S1 and to the rail at the other. The secondary winding of T1 comprises N windings, each connected to the left-side rectifier of one of the N back-to-back H-bridge converters. The right-side inverters of the N back-to-back H-bridge converters are cascaded and connected to the primary winding of T2. The secondary winding of T2 is connected to the contact wire at one end via a double-pole switch S2 and to the high-speed train at the other end via a double-pole switch S2. The high-speed train is also connected to the contact wire via switch S3.

[0007] Step 1: Disconnect S1 and S2, and close S3 to put the high-speed train into preparation mode.

[0008] Step 2: Close S1 to connect the input terminal of T1 to the contact wire;

[0009] Step 3: At the beginning of each sampling period, sample the input voltage, input current, and DC-side voltage of the left rectifier of the N back-to-back H-bridge converters; use the dual closed-loop dq current decoupling control method to obtain 4N switching control signals, which control the switching on and off of the left rectifier, so that the DC-side voltage of the left rectifier is stabilized at the reference value v. dc ref ;

[0010] Step 4: Set the modulation signal of the right-side cascaded inverter to 0, and use the unipolar frequency doubling carrier phase-shifting sinusoidal pulse width modulation method to obtain 4N switch control signals to control the on and off of the right-side cascaded inverter, so that the right-side cascaded converter outputs 0V disturbance voltage.

[0011] Step 5: Close S2 and open S3. After the high-speed train resumes stable operation, collect its AC side input voltage v0(t) and input current i0(t).

[0012] Step six: Divide the target frequency band for impedance measurement into multiple frequency bands: [Δf 1st

[50] Hz is used as the first frequency band, [50+Δf 2nd

[150] Hz is used as the second frequency band, [150+Δf 3th

[250] Hz is used as the third frequency band, [250+Δf 4th ,350]Hz is the 4th frequency band, and so on; where Δf 1st , Δf 2nd , Δf 3rd , Δf 4thThe perturbation frequency resolutions are for the first, second, third, and fourth frequency bands, respectively.

[0013] Construct odd-band multi-frequency perturbation signals v p_odd (t) and even-frequency band multi-frequency disturbance signal v p_even (t); the odd-frequency band multi-frequency disturbance signal v p_odd (t) is:

[0014]

[0015] Wherein, the perturbation frequency resolution is Δf 1st , Δf 3rd , Δf 5th ... are all set as the initial frequency resolution Δf; N odd N represents the total number of disturbance frequencies in the odd-numbered frequency bands. 1st N 3rd N 5th ... represent the number of disturbance frequencies in the first frequency band, the third frequency band, the fifth frequency band, ... respectively;

[0016]

[0017] The even-frequency band multi-frequency disturbance signal v p_even (t) is:

[0018]

[0019] Wherein, the perturbation frequency resolution is Δf 2nd , Δf 4th , Δf 6th ... are all set as the initial frequency resolution Δf; N even N is the total number of even-numbered frequency band perturbation frequencies; 2nd N 4th N 6th ... represent the number of disturbance frequencies in the 2nd, 4th, 6th, ... frequency bands, respectively;

[0020]

[0021] The v p_odd (t) and v p_even In (t), r is the amplitude adjustment factor, set as the initial value r. init ;

[0022] Step 7, Adjust the disturbance amplitude: Set the upper and lower limits of limiter 1 to 0.2V respectively. dc refThe upper and lower limits of limiter 2 are set to 0.6 and 0.1, respectively; the DC-side voltage of the left rectifier of each back-to-back H-bridge converter is collected, and the average DC-side voltage is calculated; the difference between the average DC-side voltage and the DC voltage reference value is used to obtain the fluctuation Δv. dc Then calculate |Δv dc |;|Δv dc After being processed by limiter 1, the difference between the value and the limiter itself is calculated, and then the result is sent to limiter 2 via a PI controller to obtain the initial setpoint r. init The negative feedback quantity Δr; the amplitude adjustment factor r is adjusted from the initial value r init Adjusted to (r) init +Δr);

[0023] Step 8: Set the modulation signal of the right-side cascaded inverter to v. p_odd (t) Using a unipolar frequency-doubled carrier phase-shift sinusoidal pulse width modulation method, 4N switch control signals are obtained to control the on-off state of the right-side cascaded inverter, causing the right-side cascaded inverter to output odd-band wideband voltage disturbances, which are then coupled and series-injected into the AC side of the high-speed train through a wideband transformer. After the high-speed train stabilizes, the AC side time-domain voltage response v is collected. odd (t) and current response i odd (t);

[0024] Step nine: Restore the modulation signal to 0, causing the right-side cascaded inverter to output a 0V disturbance voltage, and clear the output and integral terms of the PI controller. Wait until the DC-side voltage of the left-side rectifier stabilizes again at the reference value V. dc ref ;

[0025] Step 10: After adjusting the disturbance amplitude using the same method as in Step 7, set the modulation signal of the right-side cascaded inverter to v. p_even (t) Using a unipolar frequency-doubled carrier phase-shift sinusoidal pulse width modulation method, 4N switch control signals are obtained to control the on-off state of the right-side cascaded inverter, causing the right-side cascaded inverter to output even-frequency wideband voltage disturbances, which are then coupled and series-injected into the AC side of the high-speed train through a wideband transformer. After the high-speed train stabilizes, the AC side time-domain voltage response v is collected. even (t) and current response i even (t);

[0026] Step 11: Using the FFT algorithm, transform v0(t) and i0(t) into v0(jω) and i0(jω) respectively, and then convert v... odd (t) and i odd (t) is converted to v odd (jω) and i odd (jω), v even (t) and i even(t) is converted to v even (jω) and i even (jω); by extracting v0(jω), i0(jω), and v in one go odd (jω) and i odd The frequency response data v0(jω) for each odd-numbered frequency band in (jω) odd ), i0(jω odd ), v odd (jω odd ) and i odd (jω odd The impedance Z(jω) of the high-speed train in each odd-numbered frequency band was calculated. odd Similarly, by extracting v0(jω), i0(jω), and v in one step... even (jω) and i even The frequency response data v0(jω) for each even-numbered frequency band in (jω) even ), i0(jω even ), v even (jω even ) and i odd (jω even The impedance Z(jω) of the high-speed train in each even-numbered frequency band was calculated. even );

[0027]

[0028]

[0029] Further technical solutions also include:

[0030] Step 12: Calculate the volatility of the amplitude-frequency response curve in the k-th frequency band, where k = 1, 2, ..., P, and P is the total number of frequency bands.

[0031] 12.1 Impedance Z(jω) of all odd-numbered frequency bands odd ) and the impedance Z(jω) of all even frequency bands even ), thus obtaining the impedance amplitude-frequency response curves after combining all frequency bands;

[0032] 12.2 Integrate the amplitudes corresponding to all odd-multiple frequency resolution points in the k-th frequency band respectively:

[0033]

[0034] Where g(·) represents the amplitude at the corresponding frequency point, f 1st f represents the first odd-multiple frequency resolution point in the k-th frequency band. Mthf represents the last odd-multiple frequency resolution point in the k-th frequency band, and M represents the number of frequency points from the first to the last odd-multiple frequency resolution point in the k-th frequency band; jth Indicates in f 1st to f Mth The j-th frequency point in the frequency range;

[0035] 12.3 For the impedance amplitude-frequency response curve in the k-th frequency band, f 1st f Mth Integrate the amplitudes at all frequency points between the two:

[0036]

[0037] 12.4 Calculate the variability FR of the impedance amplitude-frequency response curve in the k-th frequency band. kth :

[0038]

[0039] Step 13, set the volatility FR kth The maximum threshold is ε, which is related to the volatility FR of the amplitude-frequency response curve of the k-th frequency band. kth Compare and determine whether the perturbation frequency resolution of the k-th frequency band needs to be reset: if FR kth If ε is less than or equal to 0, then the initial perturbation frequency resolution Δf of the k-th frequency band meets the impedance measurement requirements. The perturbation frequency resolution of this frequency band is not reset, and the impedance measured in step eleven is used as the final measurement result for this frequency band. If FR kth If the value is greater than ε, then reset the perturbation frequency resolution of the k-th frequency band:

[0040]

[0041] Where Round(·) is the nearest integer function;

[0042] Step fourteen, use the reset perturbation frequency resolution Δf of the k-th frequency band. kth Reset the odd-band multi-frequency disturbance signal and the even-band multi-frequency disturbance signal in step six;

[0043] 14.1 Using the perturbation frequency resolution Δf of all reset k-th frequency bands kth When k is an odd number, reset the odd-frequency band multi-frequency disturbance signal v. p_odd (t), specifically: the resolution Δf of the perturbation frequency of the reset k-th frequency band. kth Substitute into the following formula, discard all terms related to the unreset perturbation frequency resolution, and set the number of perturbation frequencies corresponding to all odd-numbered frequency bands without reset perturbation frequency resolution to 0.

[0044]

[0045] 14.2 Using the perturbation frequency resolution Δf of all reset k-th frequency bands kth If k is an even number, reset the even-numbered frequency band multi-frequency disturbance signal v. p_even (t), specifically: the resolution Δf of the perturbation frequency of the reset k-th frequency band. kth Substitute into the following formula, discard all terms related to the unreset perturbation frequency resolution, and set the number of perturbation frequencies corresponding to all even-numbered frequency bands without reset perturbation frequency resolution to 0.

[0046]

[0047] Step 15: Return to Step 7 and remeasure the impedance of the frequency band where the volatility is greater than the threshold ε.

[0048] The beneficial effects of this invention are: by combining a disturbance generation device and utilizing odd-even segmented multi-frequency disturbance signals and an adaptive broadband voltage disturbance control method, adaptive broadband voltage disturbances in odd or even frequency bands can be injected into high-speed trains, enabling safe, accurate, and rapid measurement of the impedance characteristics of high-speed trains. This invention has the following advantages:

[0049] First, the generated odd and even segmented multi-frequency voltage disturbances can avoid the influence of the frequency overlap effect of high-speed trains on impedance measurement during broadband injection, thus improving the accuracy of broadband impedance measurement of high-speed trains.

[0050] Second, by adaptively adjusting the amplitude of the disturbance according to the DC-side voltage fluctuation of the disturbance generation device, excessive disturbance can be prevented from affecting the normal operation of the system and ensure measurement safety.

[0051] Third, by adaptively adjusting the frequency resolution based on the fluctuation level of the impedance amplitude-frequency characteristic curve, the measurement accuracy of the frequency band with large impedance curve fluctuations can be further improved. Attached Figure Description

[0052] Figure 1 This is a schematic diagram of a multi-frequency disturbance signal segmented into odd and even frequencies.

[0053] Figure 2 This is a schematic diagram of impedance measurement for VSC high-speed trains based on adaptive broadband disturbance injection.

[0054] Figure 3 This is an adaptive control block diagram for the disturbance generation device. Detailed Implementation

[0055] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0056] like Figure 2 As shown, a disturbance generation device is connected to the high-speed railway network system. The disturbance generation device includes a multi-winding step-down transformer T1, N back-to-back H-bridge converters, and a wideband coupling transformer T2. The primary winding of T1 is connected to the contact wire at one end via switch S1 and to the rail at the other end. The secondary winding of T1 includes N windings, each connected to the left-side rectifier of one of the N back-to-back H-bridge converters. The right-side inverters of the N back-to-back H-bridge converters are cascaded and connected to the primary winding of T2. The secondary winding of T2 is connected to the contact wire at one end via double-pole switch S2 and to the high-speed train at the other end via double-pole switch S2. The high-speed train is also connected to the contact wire via switch S3.

[0057] Combination Figure 3 Perform broadband impedance measurement of high-speed trains according to the following steps:

[0058] 1.1 Disconnect switches S1 and S2, close switch S3, and the high-speed train draws power from the 25kV contact line and runs in the preparation condition;

[0059] 1.2 Close switch S1 to connect the input terminal of the multi-winding step-down transformer to the contact line;

[0060] 1.3 At the beginning of each sampling period, the input voltage v of the left rectifier of each of the N back-to-back H-bridge converters is... sk Input current i sk DC side voltage v dck Sampling is performed, k = 1, 2, 3...N; using a dual closed-loop dq current decoupling control strategy, 4N switch control signals are obtained to control the switching on and off of the left rectifiers of N back-to-back H-bridge converters, so that the DC side voltage of the left rectifier is stabilized at the reference value v. dc ref ;

[0061] 1.4 Set the modulation signal of the right-side cascaded inverter to 0, and obtain 4N switching control signals through the unipolar frequency doubling carrier phase shift sinusoidal pulse width modulation strategy (CPS-SPWM) to control the turn-on and turn-off of the right-side cascaded inverter, so that the right-side cascaded inverter outputs 0V disturbance voltage.

[0062] 1.5 Close S2 and open S3. After the high-speed train resumes stable operation, collect the AC input voltage v0(t) and input current i0(t) of the high-speed train.

[0063] 1.6 Divide the target measurement frequency band of impedance measurement into odd-numbered and even-numbered frequency bands: [Δf 1st

[50] Hz is used as the first frequency band, [50+Δf 2nd

[150] Hz is used as the second frequency band, [150+Δf 3th

[250] Hz is used as the third frequency band, [250+Δf 4th ,350]Hz is the 4th frequency band, and so on; where Δf 1st , Δf 2nd , Δf 3rd , Δf 4th The perturbation frequency resolutions are for the first, second, third, and fourth frequency bands, respectively.

[0064] 1.7 Construct a multi-frequency disturbance signal in odd-band frequencies, and set the amplitude adjustment factor r to the initial value r. init ;

[0065] Odd-band multi-frequency disturbance signal v p_odd (t) is:

[0066]

[0067] Wherein, the perturbation frequency resolution is Δf 1st , Δf 3rd , Δf 5th ... are all set as the initial frequency resolution Δf; N odd N represents the total number of disturbance frequencies in the odd-numbered frequency bands. 1st N 3rd N 5th ... represent the number of disturbance frequencies in the first frequency band, the third frequency band, the fifth frequency band, ... respectively;

[0068]

[0069] 1.8 Set the upper and lower limits of limiter 1 to 0.2V respectively. dc ref The upper and lower limits of limiter 2 are set to 0.6 and 0.1 respectively. The DC side voltage v of the left rectifier of each back-to-back H-bridge converter is collected. dck Given k = 1, 2, 3..., calculate the average value of the DC-side voltage and subtract it from the DC voltage reference value to obtain the fluctuation Δv. dc Then find its absolute value |Δv dc The value is calculated by subtracting the value from itself after passing through limiter 1, and then output to limiter 2 via PI controller to obtain the initial setpoint r. init The negative feedback quantity Δr is used to adjust the amplitude adjustment factor from the initial value r. init Adjusted to (r) init +Δr); The adjustment effect is as follows: when the DC voltage fluctuation |Δv is detected dc | Less than the upper threshold of limiter 1, 0.2V dc ref At that time, Δr equals 0, and the amplitude adjustment factor r is the initial value r. initConversely, if Δr is positive, the amplitude adjustment factor r will change from r init It keeps decreasing until |Δv dc | Less than 0.2v dc ref Alternatively, it can reach the lower limit of 0.1 of limiter 2, thereby enabling adaptive adjustment of the disturbance amplitude based on the DC side voltage fluctuation to prevent excessive disturbance energy from disrupting the normal operation of the system.

[0070] 1.9 Let the modulation signal of the cascaded inverter on the right be v. p_odd (t) Using a unipolar frequency-doubled carrier phase-shift sinusoidal pulse width modulation method, 4N switch control signals are obtained to control the on-off state of the right-side cascaded inverter, causing the right-side cascaded inverter to output odd-band wideband voltage disturbances. These disturbances are then coupled and series-injected into the AC side of the high-speed train through a wideband transformer. After the high-speed train stabilizes, the AC side time-domain voltage response v is collected. odd (t) and current response i odd (t);

[0071] 2.0 The modulation signal is restored to 0, causing the right-side cascaded inverter to output a 0V disturbance voltage. The output and integral terms of the PI controller in the disturbance amplitude regulation algorithm are cleared. This process continues until the DC-side voltage of the left-side rectifier stabilizes again at the reference value V. dc ref Then, enable the PI controller in the disturbance amplitude adjustment algorithm;

[0072] 2.1 Construct a multi-frequency perturbation signal in even-frequency bands, and set the amplitude adjustment factor r to the initial value r. init ;

[0073] Even-frequency band multi-frequency disturbance signal v p_even (t) is:

[0074]

[0075] Wherein, the perturbation frequency resolution is Δf 2nd , Δf 4th , Δf 6th ... are all set as the initial frequency resolution Δf; N even N is the total number of even-numbered frequency band perturbation frequencies; 2nd N 4th N 6th ... represent the number of disturbance frequencies in the 2nd, 4th, 6th, ... frequency bands, respectively;

[0076]

[0077] 2.2 Perform step 1.8 and select the modulation signal of the right-side cascaded inverter as an even-frequency band multi-frequency signal v. p_even (t), after unipolar frequency multiplication CPS-SPWM, 4N switching control signals are obtained, corresponding to the turn-on and turn-off of the right-side cascaded inverter. This causes the right-side cascaded inverter to output even-frequency wideband voltage disturbance, which is then coupled and series-injected into the AC side of the high-speed train through a wideband transformer. After the high-speed train stabilizes, the AC side time-domain voltage response v is collected. even (t) and current response i even (t);

[0078] 2.3 Using the FFT (Fast Fourier Transform) algorithm, v0(t) and i0(t) are transformed into v0(jω) and i0(jω) respectively, and v odd (t) and i odd (t) is converted to v odd (jω) and i odd (jω), v even (t) and i even (t) is converted to v even (jω) and i even (jω); by extracting v0(jω), i0(jω), and v in one go odd (jω) and i odd The frequency response data v0(jω) for each odd-numbered frequency band in (jω) odd ), i0(jω odd ), v odd (jω odd ) and i odd (jω odd The impedance Z(jω) of the high-speed train in each odd-numbered frequency band was calculated. odd Similarly, by extracting v0(jω), i0(jω), and v in one step... even (jω) and i even The frequency response data v0(jω) for each even-numbered frequency band in (jω) even ), i0(jω even ), v even (jω even ) and i odd (jω even The impedance Z(jω) of the high-speed train in each even-numbered frequency band was calculated. even );

[0079]

[0080]

[0081] To further improve the measurement accuracy in the frequency band where the impedance curve fluctuates significantly, the following steps can be performed:

[0082] 2.4 Impedance Z(jω) of all odd-numbered frequency bands odd ) and the impedance Z(jω) of all even frequency bands even This yields the impedance amplitude-frequency response curves for all frequency band combinations. The amplitudes corresponding to all odd-number multiples of the frequency resolution in the k-th frequency band are then integrated.

[0083]

[0084] Where g(·) represents the amplitude at the corresponding frequency point, f 1st f represents the first odd-multiple frequency resolution point in the k-th frequency band. Mth f represents the last odd-multiple frequency resolution point in the k-th frequency band, and M represents the number of frequency points from the first to the last odd-multiple frequency resolution point in the k-th frequency band; jth Indicates in f 1st to f Mth The j-th frequency point in the frequency range;

[0085] 2.5 Integrate the amplitudes corresponding to the first odd-multiple frequency resolution point, the last odd-multiple frequency resolution point, and all frequency points in between in the impedance amplitude-frequency response curve of the k-th frequency band:

[0086]

[0087] 2.6 Calculate the fluctuation rate FR of the impedance amplitude-frequency response curve in the k-th frequency band respectively. kth :

[0088]

[0089] 2.7 Setting the volatility FR kth The maximum threshold is ε, which is related to the volatility FR of the amplitude-frequency response curve of the k-th frequency band. kth Compare and determine whether the perturbation frequency resolution of the k-th frequency band needs to be reset: if FR kth If ε is less than or equal to 0, then the initial perturbation frequency resolution Δf of the k-th frequency band meets the impedance measurement requirements. The perturbation frequency resolution of this frequency band is not reset, and the impedance measured in step 2.3 is used as the final measurement result for this frequency band. If FR kth If the value is greater than ε, then reset the perturbation frequency resolution of the k-th frequency band:

[0090]

[0091] Where Round(·) is the nearest integer function;

[0092] 2.8 Using the perturbation frequency resolution Δf of all reset k-th frequency bands kth When k is an odd number, reset the odd-frequency band multi-frequency disturbance signal v. p_odd (t), specifically: the resolution Δf of the perturbation frequency of the reset k-th frequency band. kth Substitute into the following formula, discard all terms related to the unreset perturbation frequency resolution, and set the number of perturbation frequencies corresponding to all odd frequency bands with unreset perturbation frequency resolution to 0.

[0093]

[0094] 2.9 The resolution Δf of the perturbation frequency of all reset k-th frequency bands kth If k is an even number, reset the even-numbered frequency band multi-frequency disturbance signal v. p_even (t), specifically: the resolution Δf of the perturbation frequency of the reset k-th frequency band. kth Substitute into the following formula, discard all terms related to the unreset perturbation frequency resolution, and set the number of perturbation frequencies corresponding to all even-numbered frequency bands with unreset perturbation frequency resolution to 0.

[0095]

[0096] Examples of the methods for resetting the perturbation frequency resolution of odd and even frequency bands described above are as follows:

[0097] If the perturbation frequency resolution of bands 1, 4, 5, and 6 has been redesigned, then the updated v p_odd (t) and v p_even (t) are respectively:

[0098]

[0099]

[0100] Where, Δf 1st , Δf 4th , Δf 5th , Δf 6th For the updated perturbation frequency resolution; N 1st N 4th N 5th N 6th The disturbance frequencies are respectively those of the 1st, 4th, 5th, and 6th frequency bands.

[0101] Number; N odd =N 1st +N 5th N even =N4th +N 6th ;

[0102] For frequency bands where impedance measurement results meet the volatility threshold requirements, there is no need to participate in the construction of multi-frequency disturbance signals.

[0103] 3.0 Initiates a new round of disturbance generation and injection, and remeasures the impedance characteristics of each frequency band where the volatility is greater than the threshold ε.

Claims

1. A high-speed train impedance measurement method based on adaptive broadband voltage disturbance, wherein a voltage disturbance signal is injected by a disturbance generation device; the disturbance generation device includes a multi-winding step-down transformer T1, N back-to-back H-bridge converters, and a broadband coupling transformer T2; wherein, The primary side of T1 is connected to the contact wire at one end via switch S1 and to the rail at the other end; the secondary side of T1 includes N windings, which are respectively connected to the left rectifiers of N back-to-back H-bridge converters. The right-side inverters of N back-to-back H-bridge converters are cascaded and connected to the primary side of T2; one end of the secondary side of T2 is connected to the contact line through a double-pole switch S2, and the other end is connected to the high-speed train through a double-pole switch S2; the high-speed train is also connected to the contact line through switch S3. Its features include: Step 1: Disconnect S1 and S2, and close S3 to put the high-speed train into preparation mode. Step 2: Close S1 to connect the input terminal of T1 to the contact wire; Step 3: At the beginning of each sampling period, sample the input voltage, input current, and DC-side voltage of the left rectifier of the N back-to-back H-bridge converters; use the dual closed-loop dq current decoupling control method to obtain 4N switching control signals, which control the switching on and off of the left rectifier, so that the DC-side voltage of the left rectifier is stabilized at the reference value v. dc ref ; Step 4: Set the modulation signal of the right-side cascaded inverter to 0, and use the unipolar frequency doubling carrier phase-shifting sinusoidal pulse width modulation method to obtain 4N switch control signals to control the on and off of the right-side cascaded inverter, so that the right-side cascaded converter outputs 0V disturbance voltage. Step 5: Close S2 and open S3. After the high-speed train resumes stable operation, collect its AC side input voltage v0(t) and input current i0(t). Step six: Divide the target frequency band for impedance measurement into multiple frequency bands: [Δf 1st [50]Hz is used as the first frequency band, [50+Δf 2nd [150]Hz is used as the second frequency band, [150+Δf 3th 250 Hz is used as the third frequency band. [250+Δf 4th ,350]Hz is the 4th frequency band, and so on; where Δf 1st , Δf 2nd , Δf 3rd , Δf 4th The perturbation frequency resolutions for the first, second, third, and fourth frequency bands are given respectively; and multi-frequency perturbation signals v for odd-numbered frequency bands are constructed respectively. p_odd (t) and even-frequency band multi-frequency disturbance signal v p_even (t); The odd-frequency band multi-frequency perturbation signal v p_odd (t) is: Wherein, the perturbation frequency resolution is Δf 1st , Δf 3rd , Δf 5th ... are all set as the initial frequency resolution Δf; N odd N represents the total number of disturbance frequencies in the odd-numbered frequency bands. 1st N 3rd N 5th ... represent the number of disturbance frequencies in the first frequency band, the third frequency band, the fifth frequency band, ... respectively; The even-frequency band multi-frequency disturbance signal v p_even (t) is: Wherein, the perturbation frequency resolution is Δf 2nd , Δf 4th , Δf 6th ... are all set as the initial frequency resolution Δf; N even N is the total number of even-numbered frequency band perturbation frequencies; 2nd N 4th N 6th ... represent the number of disturbance frequencies in the 2nd, 4th, 6th, ... frequency bands, respectively; The v p_odd (t) and v p_even In (t), r is the amplitude adjustment factor, set as the initial value r. init ; Step 7, Adjust the disturbance amplitude: Set the upper and lower limits of limiter 1 to 0.2V respectively. dc ref The upper and lower limits of limiter 2 are set to 0.6 and 0.1, respectively; the DC-side voltage of the left rectifier of each back-to-back H-bridge converter is collected, and the average DC-side voltage is calculated; the difference between the average DC-side voltage and the DC voltage reference value is used to obtain the fluctuation Δv. dc Then calculate |Δv dc |;|Δv dc After being processed by limiter 1, the difference between the value and the limiter itself is calculated, and then the result is sent to limiter 2 via a PI controller to obtain the initial setpoint r. init The negative feedback quantity Δr; the amplitude adjustment factor r is adjusted from the initial value r init Adjusted to (r) init +Δr); Step 8: Set the modulation signal of the right-side cascaded inverter to v. p_odd (t) Using a unipolar frequency-doubled carrier phase-shift sinusoidal pulse width modulation method, 4N switch control signals are obtained to control the on-off state of the right-side cascaded inverter, causing the right-side cascaded inverter to output odd-band wideband voltage disturbances, which are then coupled and series-injected into the AC side of the high-speed train through a wideband transformer. After the high-speed train stabilizes, the AC side time-domain voltage response v is collected. odd (t) and current response i odd (t); Step nine: Restore the modulation signal to 0, causing the right-side cascaded inverter to output a 0V disturbance voltage, and clear the output and integral terms of the PI controller. Wait until the DC-side voltage of the left-side rectifier stabilizes again at the reference value ref. v dc ； Step 10: After adjusting the disturbance amplitude using the same method as in Step 7, set the modulation signal of the right-side cascaded inverter to v. p_even (t) Using a unipolar frequency-doubled carrier phase-shift sinusoidal pulse width modulation method, 4N switch control signals are obtained to control the on-off state of the right-side cascaded inverter, causing the right-side cascaded inverter to output even-frequency wideband voltage disturbances, which are then coupled and series-injected into the AC side of the high-speed train through a wideband transformer. After the high-speed train stabilizes, the AC side time-domain voltage response v is collected. even (t) and current response i even (t); Step eleven, using the FFT algorithm, transform v0(t) and i0(t) into v0(jω) and i0(jω) respectively, and then convert v odd (t) and i odd (t) is converted to v odd (jω) and i odd (jω), v even (t) and i even (t) is converted to v even (jω) and i even (jω); by extracting v0(jω), i0(jω), and v in one go odd (jω) and i odd The frequency response data v0(jω) for each odd-numbered frequency band in (jω) odd ), i0(jω odd ), v odd (jω odd ) and i odd (jω odd The impedance Z(jω) of the high-speed train in each odd-numbered frequency band was calculated. odd Similarly, by extracting v0(jω), i0(jω), and v in one step... even (jω) and i even The frequency response data v0(jω) for each even-numbered frequency band in (jω) even ), i0(jω even ), v even (jω even ) and i odd (jω even The impedance Z(jω) of the high-speed train in each even-numbered frequency band was calculated. even ); 2. The high-speed train impedance measurement method as described in claim 1, characterized in that, Also includes: Step 12: Calculate the volatility of the amplitude-frequency response curve in the k-th frequency band, where k = 1, 2, ..., P, and P is the total number of frequency bands. (12.1) The impedance Z(jω) of all odd-numbered frequency bands odd ) and the impedance Z(jω) of all even frequency bands even ), thus obtaining the impedance amplitude-frequency response curves after combining all frequency bands; (12.2) Integrate the amplitudes corresponding to all odd-multiple frequency resolutions in the k-th frequency band respectively: Where g(·) represents the amplitude at the corresponding frequency point, f 1st f represents the first odd-multiple frequency resolution point in the k-th frequency band. Mth f represents the last odd-multiple frequency resolution point in the k-th frequency band, and M represents the number of frequency points from the first to the last odd-multiple frequency resolution point in the k-th frequency band; jth Indicates in f 1st to f Mth The j-th frequency point in the frequency range; (12.3) For the impedance amplitude-frequency response curve in the k-th frequency band, f 1st f Mth Integrate the amplitudes at all frequency points between the two: (12.4) Calculate the fluctuation rate FR of the impedance amplitude-frequency response curve in the k-th frequency band respectively. kth : Step 13, set the volatility FR kth The maximum threshold is ε, which is related to the volatility FR of the amplitude-frequency response curve of the k-th frequency band. kth Compare and determine whether the perturbation frequency resolution of the k-th frequency band needs to be reset: if FR kth If ε is less than or equal to 0, then the initial perturbation frequency resolution Δf of the k-th frequency band meets the impedance measurement requirements. The perturbation frequency resolution of this frequency band is not reset, and the impedance measured in step eleven is used as the final measurement result for this frequency band. If FR kth If the value is greater than ε, then reset the perturbation frequency resolution of the k-th frequency band: Where Round(·) is the nearest integer function; Step fourteen, use the reset perturbation frequency resolution Δf of the k-th frequency band. kth Reset the odd-band multi-frequency disturbance signal and the even-band multi-frequency disturbance signal in step six; (14.1) Use the perturbation frequency resolution Δf of all reset k-th frequency bands. kth When k is an odd number, reset the odd-frequency band multi-frequency disturbance signal v. p_odd (t), specifically: the resolution Δf of the perturbation frequency of the reset k-th frequency band. kth Substitute into the following formula, discard all terms related to the unreset perturbation frequency resolution, and set the number of perturbation frequencies corresponding to all odd-numbered frequency bands without reset perturbation frequency resolution to 0. (14.2) Use the perturbation frequency resolution Δf of all reset k-th frequency bands. kth If k is an even number, reset the even-numbered frequency band multi-frequency disturbance signal v. p_even (t), specifically: the resolution Δf of the perturbation frequency of the reset k-th frequency band. kth Substitute into the following equation, and discard all terms related to the unreset perturbation frequency resolution, and Set the number of perturbation frequencies corresponding to all even-numbered frequency bands for which the perturbation frequency resolution has not been reset to 0. Step 15: Return to Step 7 and remeasure the impedance of the frequency band where the volatility is greater than the threshold ε.

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