Active suppression method and system for closing excitation inrush current of train traction transformer

Abstract

The present application provides a method and system for actively suppressing the magnetizing inrush current of the train traction transformer during closing, wherein the method includes: stabilizing the intermediate DC voltage of the intermediate DC circuit of the train traction system according to the train running condition; constructing a three-phase phase-locked method using a second-order generalized integral to obtain the grid voltage frequency, phase and voltage amplitude; detecting the grid voltage, and when the grid voltage passes through zero, simultaneously starting the four-quadrant rectifier module of the train traction system, and adjusting the output of the four-quadrant rectifier module according to the grid voltage frequency, phase and voltage amplitude and the intermediate DC voltage, so that the primary voltage of the traction transformer of the train traction system is consistent with the grid voltage; detecting the current secondary component of the four-quadrant rectifier module, and when the current secondary component reaches a set value, closing the circuit breaker of the train traction system. The present application can effectively suppress the magnetizing inrush current generated when the circuit breaker is closed.

Description

Technical Field

[0001] The present application relates to the field of high-voltage electrical technology for rail transit, and in particular to a method and system for actively suppressing a closing excitation inrush current of a train traction transformer. Background Art

[0002] Electrified railways usually use a phase-switching and phase-changing power supply method to ensure the three-phase load balance of the power system. To prevent interphase short circuits, a phase separation zone is set at the connection between different phase power supply arms and is separated by an insulating device. When the train passes through the phase separation process, there is a short-term power outage, which will cause speed loss and safety hazards to the train.

[0003] In the industry, electrified railways widely adopt the form of on-board over-phase separation, that is, passing through the phase separation area by disconnecting the main circuit breaker. Electrified railways generally set up a phase separation area every 20 to 30 km, so the circuit breaker of the high-speed EMU will generate an opening / closing operation every 3 to 5 minutes due to over-phase separation. When the train passes through the phase separation area and closes the main circuit breaker, the traction transformer core will be oversaturated due to the sudden increase in the primary voltage of the traction transformer and the existence of the residual magnetism of the core, which will cause a very large excitation inrush current. The magnitude of the excitation inrush current can reach several times the rated current, which will have a very large impact on high-voltage equipment such as the EMU circuit breaker, causing equipment damage; in addition, the excitation inrush current of the traction transformer is also very likely to cause an overcurrent fault on the primary side of the train traction transformer or an overcurrent fault on the AC side of the rectifier.

[0004] Therefore, how to effectively suppress the excitation inrush current generated when the circuit breaker is closed is a technical problem that needs to be solved urgently by those skilled in the art. Summary of the invention

[0005] In order to solve the above technical problems, the present application provides a method for actively suppressing the magnetizing inrush current when the train traction transformer is closed, which can effectively suppress the magnetizing inrush current generated when the circuit breaker is closed. The present application also provides a system for actively suppressing the magnetizing inrush current when the train traction transformer is closed, which has the same technical effect.

[0006] The first objective of the present application is to provide a method for actively suppressing the closing excitation inrush current of a train traction transformer.

[0007] The above-mentioned application objective 1 of the present application is achieved through the following technical solutions:

[0008] A method for actively suppressing a closing excitation inrush current of a train traction transformer is applied to a train traction system, and the method comprises:

[0009] According to the train running condition, stabilizing the intermediate DC voltage of the intermediate DC circuit of the train traction system;

[0010] The three-phase phase-locking method is constructed by using second-order generalized integral to obtain the grid voltage frequency, phase and voltage amplitude;

[0011] Detecting the grid voltage, and when the grid voltage passes through a zero point, simultaneously starting the four-quadrant rectifier module of the train traction system, and adjusting the output of the four-quadrant rectifier module according to the grid voltage frequency, phase, voltage amplitude and the intermediate DC voltage, so that the primary voltage of the traction transformer of the train traction system is consistent with the grid voltage;

[0012] The secondary component of the current of the four-quadrant rectifier module is detected, and when the secondary component of the current reaches a set value, the circuit breaker of the train traction system is closed.

[0013] Preferably, in the active suppression method for closing excitation inrush current of the train traction transformer, when the train operating condition is an over-phase condition, stabilizing the intermediate DC voltage of the intermediate DC circuit of the train traction system according to the train operating condition includes:

[0014] When the train is in the over-phase condition, before the train enters the phase separation area, the circuit breaker is controlled to disconnect, the four-quadrant rectifier module stops working, the inverter module of the train traction system unloads the torque and enters the micro-braking mode to stabilize the intermediate DC voltage of the intermediate DC circuit of the train traction system.

[0015] Preferably, in the method for actively suppressing the closing excitation inrush current of the train traction transformer, when the train operating condition is a stationary condition, stabilizing the intermediate DC voltage of the intermediate DC circuit of the train traction system according to the train operating condition includes:

[0016] When the train is in the stationary condition, the battery of the train traction system is controlled to provide energy to the auxiliary transformer module of the train traction system through the bidirectional charger of the train traction system to stabilize the intermediate DC voltage of the intermediate DC circuit of the train traction system.

[0017] Preferably, in the active suppression method for closing excitation inrush current of the train traction transformer, the method of using second-order generalized integral to construct a three-phase phase-locked mode to obtain the grid voltage frequency, phase and voltage amplitude includes:

[0018] Using the second-order generalized integral, two mutually orthogonal signals are generated and ;

[0019] According to the signal and Perform park transformation to obtain the voltage components of the dq axis of the three-phase synchronous rotating coordinate system;

[0020] The q-axis component of the dq-axis voltage component , do PI closed-loop regulation so that the q-axis component is 0 to obtain the grid voltage frequency, phase and voltage amplitude after phase locking, where PI stands for Proportional-Integral.

[0021] Preferably, in the active suppression method for closing excitation inrush current of the train traction transformer, the signal and The calculation formula is as follows:

[0022] ;

[0023] ;

[0024] In the formula, represents the orthogonal signal 1, represents the quadrature signal 2, Indicates the grid voltage, represents the complex frequency domain, represents the resonant frequency of the second-order generalized integral, Represents the closed-loop coefficient.

[0025] Preferably, in the active suppression method of the closing excitation inrush current of the train traction transformer, adjusting the output of the four-quadrant rectifier module according to the grid voltage frequency, phase and voltage amplitude and the intermediate DC voltage so that the primary voltage of the traction transformer of the train traction system is consistent with the grid voltage includes:

[0026] According to the grid voltage frequency, phase and voltage amplitude and the intermediate DC voltage, the output of the four-quadrant rectifier module is adjusted to control the primary voltage of the traction transformer of the train traction system, which rises according to the amplitude increase set value curve so that the primary voltage of the traction transformer of the train traction system is consistent with the grid voltage.

[0027] Preferably, in the method for actively suppressing the closing excitation inrush current of the train traction transformer, after simultaneously starting the four-quadrant rectifier module of the train traction system when the grid voltage passes through zero, the method further includes:

[0028] Controlling the switching frequency of the four-quadrant rectifier module to be a preset multiple of the rated operating frequency;

[0029] The four-quadrant rectifier modules corresponding to the multiple secondary windings of the traction transformer are controlled to perform multi-carrier phase shifting.

[0030] Preferably, in the active suppression method for closing excitation inrush current of the train traction transformer, the four-quadrant rectifier module is n-fold, and the four-quadrant rectifier modules corresponding to the multiple secondary windings of the traction transformer are controlled to perform multi-carrier phase shifting, including:

[0031] The carrier phases of the n-fold four-quadrant rectifier modules are controlled to be staggered in sequence by the same π / n phase angle, so that the higher harmonics of the output voltage of each fold of the four-quadrant rectifier modules are staggered.

[0032] The second object of the present application is to provide an active suppression system for closing excitation inrush current of a train traction transformer.

[0033] The second application objective of the present application is achieved through the following technical solutions:

[0034] An active suppression system for closing excitation inrush current of a train traction transformer is applied to a train traction system. The active suppression system for closing excitation inrush current of a train traction transformer comprises:

[0035] A processing unit, used for stabilizing an intermediate DC voltage of an intermediate DC circuit of the train traction system according to a train running condition;

[0036] An acquisition unit is used to construct a three-phase phase-locked mode by using a second-order generalized integral to obtain a grid voltage frequency, phase and voltage amplitude;

[0037] A control unit, configured to detect a grid voltage, and when the grid voltage passes through a zero point, simultaneously start a four-quadrant rectifier module of the train traction system, and adjust an output of the four-quadrant rectifier module according to the grid voltage frequency, phase, voltage amplitude and the intermediate DC voltage, so that a primary voltage of a traction transformer of the train traction system is consistent with the grid voltage;

[0038] The control unit is also used to detect the secondary component of the current of the four-quadrant rectifier module, and when the secondary component of the current reaches a set value, close the circuit breaker of the train traction system.

[0039] Preferably, in the active suppression system for closing excitation inrush current of the train traction transformer, when the train operating condition is an over-phase condition, the processing unit, when executing the step of stabilizing the intermediate DC voltage of the intermediate DC circuit of the train traction system according to the train operating condition, is specifically used to:

[0040] When the train is in the over-phase condition, before the train enters the phase separation area, the circuit breaker is controlled to disconnect, the four-quadrant rectifier module stops working, the inverter module of the train traction system unloads the torque and enters the micro-braking mode to stabilize the intermediate DC voltage of the intermediate DC circuit of the train traction system.

[0041] Preferably, in the active suppression system for closing excitation inrush current of the train traction transformer, when the train operating condition is a stationary condition, the processing unit, when executing the step of stabilizing the intermediate DC voltage of the intermediate DC circuit of the train traction system according to the train operating condition, is specifically used to:

[0042] When the train is in the stationary condition, the battery of the train traction system is controlled to provide energy to the auxiliary transformer module of the train traction system through the bidirectional charger of the train traction system to stabilize the intermediate DC voltage of the intermediate DC circuit of the train traction system.

[0043] Preferably, in the active suppression system for closing excitation inrush current of the train traction transformer, the acquisition unit, when executing the three-phase phase-locking method constructed by using second-order generalized integral to obtain the grid voltage frequency, phase and voltage amplitude, is specifically used to:

[0044] Using the second-order generalized integral, two mutually orthogonal signals are generated and ;

[0045] According to the signal and , perform park transformation to obtain the voltage components of the dq axis of the three-phase synchronous rotating coordinate system;

[0046] The q-axis component of the dq-axis voltage component , do PI closed-loop regulation so that the q-axis component is 0 to obtain the grid voltage frequency, phase and voltage amplitude after phase locking, where PI stands for Proportional-Integral.

[0047] Preferably, in the active suppression system for closing excitation inrush current of the train traction transformer, the signal and The calculation formula is as follows:

[0048] ;

[0049] ;

[0050] In the formula, represents the orthogonal signal 1, represents the quadrature signal 2, Indicates the grid voltage, represents the complex frequency domain, represents the resonant frequency of the second-order generalized integral, Represents the closed-loop coefficient.

[0051] Preferably, in the active suppression system of the closing excitation inrush current of the train traction transformer, the control unit, when executing the step of adjusting the output of the four-quadrant rectifier module according to the grid voltage frequency, phase, voltage amplitude and the intermediate DC voltage so that the primary voltage of the traction transformer of the train traction system is consistent with the grid voltage, is specifically used to:

[0052] According to the grid voltage frequency, phase and voltage amplitude and the intermediate DC voltage, the output of the four-quadrant rectifier module is adjusted to control the primary voltage of the traction transformer of the train traction system, which rises according to the amplitude increase set value curve so that the primary voltage of the traction transformer of the train traction system is consistent with the grid voltage.

[0053] Preferably, in the active suppression system of the closing excitation inrush current of the train traction transformer, the control unit is also used to control the switching frequency of the four-quadrant rectifier module to a preset multiple of the rated operating frequency after the grid voltage passes through zero and the four-quadrant rectifier module of the train traction system is started at the same time; and control the four-quadrant rectifier modules corresponding to the multiple secondary windings of the traction transformer to perform multiple carrier phase shifting.

[0054] Preferably, in the active suppression system for closing excitation inrush current of the train traction transformer, the four-quadrant rectifier module is n-fold, and the control unit, when executing the control of the four-quadrant rectifier modules corresponding to the multiple secondary windings of the traction transformer to perform multiple carrier phase shifting, is specifically used to:

[0055] The carrier phases of the n-fold four-quadrant rectifier modules are controlled to be staggered in sequence by the same π / n phase angle, so that the higher harmonics of the output voltage of each fold of the four-quadrant rectifier modules are staggered.

[0056] The above technical solution stabilizes the intermediate DC voltage of the intermediate DC circuit of the train traction system according to the train running conditions; uses the second-order generalized integral to construct a three-phase phase-locked method to obtain the grid voltage frequency, phase and voltage amplitude; detects the grid voltage, and when the grid voltage passes through the zero point, starts the four-quadrant rectifier module of the train traction system at the same time, and adjusts the output of the four-quadrant rectifier module according to the grid voltage frequency, phase and voltage amplitude and the intermediate DC voltage, so that the primary voltage of the traction transformer of the train traction system is consistent with the grid voltage; detects the current secondary component of the four-quadrant rectifier module, and when the current secondary component reaches the set value, closes the circuit breaker of the train traction system. In the above technical solution, the grid voltage frequency, phase and amplitude are obtained by constructing a three-phase phase-locked method using the second-order generalized integral. This method has no static error, the voltage peak calculation is stable, and it is not easily affected by harmonics. It can effectively suppress the excitation inrush current at the moment of circuit breaker closing. In addition, the above technical solution does not require the use of additional equipment, and the control process is simple and effective. In summary, the above technical solution can effectively suppress the excitation inrush current generated when the circuit breaker is closed. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0058] Figure 1 A schematic flow chart of a method for actively suppressing a closing excitation inrush current of a train traction transformer provided in an embodiment of the present application;

[0059] Figure 2 A schematic diagram of the structure of a train traction system provided in an embodiment of the present application;

[0060] Figure 3 A schematic diagram of the primary voltage increase control principle provided in an embodiment of the present application;

[0061] Figure 4 A schematic diagram of a carrier phase shift of a quadruple four-quadrant rectifier module provided in an embodiment of the present application;

[0062] Figure 5 A schematic diagram of the structure of an active suppression system for closing excitation inrush current of a train traction transformer provided in an embodiment of the present application. DETAILED DESCRIPTION

[0063] In order to enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0064] In the embodiments provided in the present application, it should be understood that the disclosed methods and systems can be implemented in other ways. The system embodiments described below are merely schematic. For example, the division of units and modules is only a logical function division. There may be other division methods in actual implementation, such as: multiple units or modules can be combined, or can be integrated into another system, or some features can be ignored, or not executed. In addition, the coupling, direct coupling, or communication connection between the components shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or modules, which can be electrical, mechanical or other forms.

[0065] In addition, all functional units in the embodiments of the present application may be integrated into one processor, or each unit may be a separate device, or two or more units may be integrated into one device; each functional unit in the embodiments of the present application may be implemented in the form of hardware or in the form of hardware plus software functional units.

[0066] A person skilled in the art can understand that all or part of the steps of the following method embodiments can be completed by program instructions and related hardware. The aforementioned program instructions can be stored in a computer-readable storage medium. When the program instructions are executed, the steps of the following method embodiments are executed; and the aforementioned storage medium includes: a mobile storage device, a read-only memory (ROM), a magnetic disk or an optical disk, and other media that can store program codes.

[0067] It should be understood that the use of "system", "device", "unit" and / or "module" in this application is only a method for distinguishing different components, elements, parts, parts or assemblies at different levels. However, if other words can achieve the same purpose, the word can be replaced by other expressions.

[0068] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, "multiple" and "several" mean two or more, unless otherwise clearly and specifically defined.

[0069] If a flow chart is used in the present application, the flow chart is used to illustrate the operations performed by the system according to the embodiment of the present application. It should be understood that the preceding or following operations are not necessarily performed accurately in order. On the contrary, each step can be processed in reverse order or simultaneously. At the same time, other operations can also be added to these processes, or a certain step or several steps of operations can be removed from these processes.

[0070] It should also be noted that, in this article, terms such as "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that an article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such articles or devices. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the article or device including the above elements.

[0071] The embodiments of the present application are written in a progressive manner.

[0072] like Figure 1 As shown, an embodiment of the present application provides a method for actively suppressing a closing excitation inrush current of a train traction transformer, which is applied to a train traction system, wherein the train traction system may be an existing train traction system; specifically, Figure 2 Taking the train traction system shown in the figure as an example, it mainly includes: pantograph, contact network, circuit breaker, traction transformer, charging and shorting contactor, four-quadrant rectifier module, intermediate DC circuit, inverter module, traction motor, auxiliary transformer module, bidirectional charger and battery. Among them, various devices and modules in the train traction system can adopt existing equipment. For example, the circuit breaker can adopt vacuum circuit breaker (VCB); the connection method of various devices and modules in the train traction system can refer to Figure 2, other existing connection methods may also be used; the train traction system may also include a voltage transformer for collecting grid voltage signals, a current transformer for collecting current signals on the primary side of the traction transformer, a primary voltage sensor for collecting voltage signals on the primary side of the traction transformer, a four-quadrant current sensor for collecting current signals, a DC voltage sensor for collecting intermediate DC voltage signals, and an inverter current sensor for collecting current signals. The present application does not impose any specific restrictions on this.

[0073] The active suppression method for closing excitation inrush current of the train traction transformer specifically includes:

[0074] S101. According to the train operation condition, stabilize the intermediate DC voltage of the intermediate DC circuit of the train traction system;

[0075] In S101, specifically, the running condition of the train can be detected by a running condition detection unit pre-installed on the train to obtain the current running condition of the train, wherein the running condition of the train can be any one of a stationary condition, an over-phase condition, and a normal running condition, and the present application does not impose any specific restrictions on the detection method of the running condition of the train. In particular, for the stationary condition and the over-phase condition, the circuit breaker in the train traction system will generate an excitation inrush current when closing the circuit breaker. In order to effectively suppress the excitation inrush current, it is necessary to first stabilize the intermediate DC voltage of the intermediate DC circuit of the train traction system according to the running condition of the train.

[0076] In some embodiments, when the train operating condition is an over-phase condition, one implementation of this step specifically includes:

[0077] When the train is in an over-phase condition, before the train enters the phase separation area, the control circuit breaker is disconnected, the four-quadrant rectifier module stops working, the inverter module of the train traction system unloads the torque and enters the micro-braking mode to stabilize the intermediate DC voltage of the intermediate DC circuit of the train traction system.

[0078] Specifically, when the train is in an over-phase condition, before the train is about to enter the phase separation area, an over-phase instruction is issued to the train traction system to control the circuit breaker to disconnect, the four-quadrant rectifier module to stop working, and the inverter module of the train traction system to unload the torque and enter the micro-braking mode, so as to stabilize the intermediate DC voltage of the intermediate DC circuit of the train traction system and allow the auxiliary transformer module, bidirectional charger and battery to maintain normal operation; among them, the micro-braking mode is a working mode for the inverter module, which can be implemented using existing control logic. For example, when it is determined that the train enters the micro-braking mode, the micro-braking request torque is calculated based on the deviation between the current intermediate DC voltage sampling value and the intermediate DC voltage target value required by the system. , sending information containing micro-braking request torque to the motor drive system, the motor drive system generates a pulse width modulation PWM signal corresponding to the micro-braking request torque, and sends the PWM signal to the traction inverter; the traction inverter generates a drive current corresponding to the micro-braking request torque according to the PWM signal, and transmits the drive current to the traction motor; the traction motor performs micro-braking according to the micro-braking request torque information carried by the drive current, converts the released kinetic energy into AC electrical energy, and transmits the converted AC power to the traction inverter; the traction inverter rectifies the AC power into DC power, and transmits the DC power to the main circuit; the main circuit supplies power to the train's electrical loads through DC power, and this application does not impose specific restrictions on this.

[0079] In other embodiments, when the train operating condition is a stationary condition, one implementation of this step specifically includes:

[0080] When the train is in a stationary condition, the battery of the train traction system is controlled to provide energy to the auxiliary transformer module of the train traction system through the bidirectional charger of the train traction system to stabilize the intermediate DC voltage of the intermediate DC circuit of the train traction system.

[0081] Specifically, when the train is in a stationary condition, the inverter module stops working, and energy is provided to the auxiliary transformer module of the train traction system through the battery of the train traction system and the bidirectional charger of the train traction system to stabilize the intermediate DC voltage of the intermediate DC circuit of the train traction system. At this time, the auxiliary transformer module is used for three-phase rectification function.

[0082] S102. Use second-order generalized integral to construct a three-phase phase-locked method to obtain the grid voltage frequency, phase and voltage amplitude;

[0083] In S102, specifically, the traditional second order generalized integrator (SOG) can generate two mutually orthogonal signals. Based on the phase-locking method of the traditional SOGI, accurate phase locking can be obtained when the grid voltage is sinusoidal and unbalanced, thereby obtaining the grid voltage signal frequency, phase and voltage amplitude after phase locking.

[0084] In some embodiments, one implementation of this step specifically includes:

[0085] S1021. Use second-order generalized integral to generate two mutually orthogonal signals and ;

[0086] In S1021, specifically, the single-phase voltage input signal needs to generate two orthogonal signals before park change. One of the voltage signals can be delayed by 90° to construct an orthogonal signal. However, when the voltage amplitude and frequency fluctuate, this method is unstable. Therefore, SOGI is used to generate two mutually orthogonal signals. and , the specific calculation formula is as follows:

[0087] ;

[0088] ;

[0089] In the formula, represents the orthogonal signal 1, represents the quadrature signal 2, Indicates the grid voltage, represents the complex frequency domain, represents the resonant frequency of the second-order generalized integral, Represents the closed-loop coefficient.

[0090] S1022. According to the signal and , perform park transformation to obtain the voltage components of the dq axis of the three-phase synchronous rotating coordinate system;

[0091] In S1022, specifically, Park's Transformation, also known as Park's Transformation, is a mutually orthogonal signal. and , after Park transformation, the voltage components of the dq axes of the three-phase synchronous rotating coordinate system can be obtained.

[0092] S1023. The q-axis component of the dq-axis voltage component , do PI closed-loop regulation so that the q-axis component is 0 to obtain the grid voltage frequency, phase and voltage amplitude after phase locking.

[0093] In S1023, specifically, the q-axis component of the dq-axis voltage component , reflects the phase relationship between the bus voltage vector and the rotating coordinate system. Therefore, the q-axis component of the dq-axis voltage component is , do PI closed-loop regulation so that the q-axis component When PI is 0, the phase-locking function can be realized, so as to obtain the grid voltage frequency, phase and voltage amplitude after phase-locking. Among them, PI stands for Proportional-Integral.

[0094] In the above steps, the three-phase phase-locked method is constructed by using the second-order generalized integral to obtain the grid voltage frequency, phase and amplitude. This method has no static error, the voltage peak calculation is stable, and it is not easily affected by harmonics.

[0095] S103. Detect the grid voltage, and when the grid voltage passes through zero, start the four-quadrant rectifier module of the train traction system at the same time, and adjust the output of the four-quadrant rectifier module according to the grid voltage frequency, phase, voltage amplitude and intermediate DC voltage, so that the primary voltage of the traction transformer of the train traction system is consistent with the grid voltage;

[0096] In S103, specifically, the grid voltage can be detected by the voltage transformer in the train traction system, and when the grid voltage passes through the zero point, the four-quadrant rectifier module of the train traction system is started at the same time. Taking the over-phase condition as an example, when the train leaves the phase-splitting area, a phase-splitting command is issued to the train traction system to start the four-quadrant rectifier module; the grid voltage frequency, phase and voltage amplitude are obtained through grid voltage phase locking, and then closed-loop adjustment is performed according to the grid voltage frequency, phase and voltage amplitude and the intermediate DC voltage to adjust the output of the four-quadrant rectifier module, so that the primary voltage of the train traction transformer increases according to a certain slope, thereby realizing the smooth excitation of the traction transformer, so that the primary voltage of the traction transformer is consistent with the grid voltage.

[0097] In some embodiments, one implementation method of the step of adjusting the output of the four-quadrant rectifier module according to the grid voltage frequency, phase, voltage amplitude and intermediate DC voltage so that the primary voltage of the traction transformer of the train traction system is consistent with the grid voltage specifically includes:

[0098] According to the grid voltage frequency, phase, voltage amplitude and intermediate DC voltage, the output of the four-quadrant rectifier module is adjusted to control the primary voltage of the traction transformer of the train traction system, which rises according to the amplitude rise set value curve to keep the primary voltage of the traction transformer of the train traction system consistent with the grid voltage.

[0099] Specifically, refer to Figure 3 The boost control principle diagram shown in the figure extracts the current of the four-quadrant rectifier module through the filter. The second harmonic component ,in, , are the angular frequencies at 50Hz and 100Hz respectively, is the notch bandwidth; the RMS effective value is calculated to obtain the magnitude of the second harmonic of the current of the four-quadrant rectifier module Considering that the main circuit breaker needs to be closed as soon as possible due to the over-phase, the rising slope of the primary voltage of the train traction transformer can be preset according to the transformer characteristics. Then, by detecting the excitation inrush current of the secondary winding, the rising slope is dynamically adjusted, and the dynamic slope factor K adj The calculation formula of (t) is as follows:

[0100] ;

[0101] The dynamic slope factor K adj (t) is related to the magnitude of the second harmonic, α is a positive proportional coefficient, which is used to adjust the sensitivity of the slope factor to the excitation inrush current. When the second harmonic increases, K adj (t) decreases, thereby slowing down the rise of the primary voltage. When the second harmonic decreases, K adj (t) increases, allowing the primary voltage to rise at a faster rate;

[0102] According to the actual rising slope , get the amplitude rise setting value curve of the primary voltage, specifically:

[0103] ;

[0104] ;

[0105] in, is the primary voltage amplitude, is the initial value of the primary voltage.

[0106] Then, according to the grid voltage frequency, phase, voltage amplitude and intermediate DC voltage, the output of the four-quadrant rectifier module is adjusted to control the primary voltage of the traction transformer of the train traction system, which rises according to the amplitude rise set value curve to achieve smooth excitation of the traction transformer, so that the primary voltage of the traction transformer of the train traction system is consistent with the grid voltage.

[0107] S104. Detect the secondary component of the current of the four-quadrant rectifier module, and when the secondary component of the current reaches a set value, close the circuit breaker of the train traction system.

[0108] In S104, specifically, the secondary component of the current of the four-quadrant rectifier module is detected in real time. When the primary voltage of the transformer is consistent in phase with the grid voltage amplitude on the power supply arm side, and the secondary component of the four-quadrant current reaches a set value, the circuit breaker of the train traction system is closed, wherein the set value can be a small value close to 0, and the present application does not impose any specific restrictions on this.

[0109] In the above embodiment, according to the train running condition, the intermediate DC voltage of the intermediate DC circuit of the train traction system is stabilized; a three-phase phase-locked method is constructed by a second-order generalized integral to obtain the grid voltage frequency, phase and voltage amplitude; the grid voltage is detected, and when the grid voltage passes through the zero point, the four-quadrant rectifier module of the train traction system is started at the same time, and the output of the four-quadrant rectifier module is adjusted according to the grid voltage frequency, phase and voltage amplitude and the intermediate DC voltage, so that the primary voltage of the traction transformer of the train traction system is consistent with the grid voltage; the current secondary component of the four-quadrant rectifier module is detected, and when the current secondary component reaches the set value, the circuit breaker of the train traction system is closed. In the above embodiment, the grid voltage frequency, phase and amplitude are obtained by constructing a three-phase phase-locked method by a second-order generalized integral. This method has no static error, the voltage peak calculation is stable, and it is not easily affected by harmonics. It can effectively suppress the excitation inrush current at the moment of closing the circuit breaker. In addition, the above embodiment does not require the use of additional equipment, and the control process is simple and effective. In summary, the above embodiment can effectively suppress the excitation inrush current generated when the circuit breaker is closed.

[0110] Since the voltage generated by the secondary winding of the traction transformer of the four-quadrant rectifier module is coupled to the primary side, the primary voltage has large harmonics. In order to effectively suppress the voltage harmonics, in other embodiments of the present application, when the grid voltage passes through zero, after the step of simultaneously starting the four-quadrant rectifier module of the train traction system, it also includes:

[0111] S201. Control the switching frequency of the four-quadrant rectifier module to be a preset multiple of the rated operating frequency;

[0112] In S201, specifically, the preset multiple may be 2 to 5 times, and by increasing the switching frequency of the four-quadrant rectifier module to the preset multiple of the rated operating frequency, it is helpful to suppress voltage harmonics.

[0113] S202. Control the four-quadrant rectifier modules corresponding to the multiple secondary windings of the traction transformer to perform multiple carrier phase shifting.

[0114] In S202, specifically, by performing multiple carrier phase shifting between four-quadrant rectifier modules corresponding to multiple secondary windings of the traction transformer, the equivalent switching frequency of the system can be further increased and the voltage harmonics can be reduced.

[0115] In some embodiments, assuming that there are n four-quadrant rectifier modules, one implementation of this step specifically includes:

[0116] The carrier phases of the n-fold four-quadrant rectifier modules are controlled to be staggered in sequence by the same π / n phase angle, so that the higher harmonics of the output voltage of each four-quadrant rectifier module are staggered.

[0117] Specifically, taking the 4-fold four-quadrant rectifier module as an example, combined with Figure 4 As shown, the carrier phases of the four-quadrant rectifier modules are staggered by the same π / 4 phase angle in sequence, so that the PWM pulses generated after modulation of each four-quadrant rectifier module are staggered by a certain angle in phase, thereby making the high-order harmonics of the output voltage of the four-quadrant rectifier module staggered, so that the voltage on the primary side of the traction transformer after superposition is closer to a sine wave.

[0118] In this embodiment, the voltage harmonics are greatly reduced by adjusting the switching frequency of the four-quadrant rectifier module and adopting the technical means of carrier phase shifting.

[0119] In other embodiments of the present application, when the train is in an over-phase condition, before the train enters the phase-separated area, the four-quadrant rectifier module is first controlled to complete smooth excitation; after the train enters the phase-separated area, the four-quadrant rectifier module is always in a started state to stabilize the primary voltage; after the train exits the phase-separated area, the three-phase phase-locked method is constructed by adopting a second-order generalized integral to obtain the grid voltage frequency, phase and amplitude to control the four-quadrant rectifier module and adjust the primary voltage. When the primary voltage of the traction transformer is consistent with the grid voltage amplitude phase, the circuit breaker is closed.

[0120] like Figure 5 As shown, in another embodiment of the present application, there is also provided an active suppression system for closing excitation inrush current of a train traction transformer, which is applied to a train traction system. The active suppression system for closing excitation inrush current of a train traction transformer comprises:

[0121] The processing unit 10 is used to stabilize the intermediate DC voltage of the intermediate DC circuit of the train traction system according to the train running condition;

[0122] An acquisition unit 11 is used to construct a three-phase phase-locked mode using a second-order generalized integral to obtain a grid voltage frequency, phase, and voltage amplitude;

[0123] The control unit 12 is used to detect the grid voltage, and when the grid voltage passes through zero, start the four-quadrant rectifier module of the train traction system at the same time, and adjust the output of the four-quadrant rectifier module according to the grid voltage frequency, phase, voltage amplitude and intermediate DC voltage, so that the primary voltage of the traction transformer of the train traction system is consistent with the grid voltage;

[0124] The control unit 12 is also used to detect the secondary component of the current of the four-quadrant rectifier module, and when the secondary component of the current reaches a set value, close the circuit breaker of the train traction system.

[0125] In other embodiments of the present application, when the train operating condition is an over-phase condition, the processing unit 10, when executing the operation of stabilizing the intermediate DC voltage of the intermediate DC circuit of the train traction system according to the train operating condition, is specifically used to:

[0126] When the train is in an over-phase condition, before the train enters the phase separation area, the control circuit breaker is disconnected, the four-quadrant rectifier module stops working, the inverter module of the train traction system unloads the torque and enters the micro-braking mode to stabilize the intermediate DC voltage of the intermediate DC circuit of the train traction system.

[0127] In other embodiments of the present application, when the train operating condition is a stationary condition, the processing unit 10, when executing the operation of stabilizing the intermediate DC voltage of the intermediate DC circuit of the train traction system according to the train operating condition, is specifically used to:

[0128] When the train is in a stationary condition, the battery of the train traction system is controlled to provide energy to the auxiliary transformer module of the train traction system through the bidirectional charger of the train traction system to stabilize the intermediate DC voltage of the intermediate DC circuit of the train traction system.

[0129] In other embodiments of the present application, the acquisition unit 11, when executing the three-phase phase-locking method constructed by using the second-order generalized integral to obtain the grid voltage frequency, phase and voltage amplitude, is specifically used to:

[0130] Using the second-order generalized integral, two mutually orthogonal signals are generated and ;

[0131] According to the signal and , perform park transformation to obtain the voltage components of the dq axis of the three-phase synchronous rotating coordinate system;

[0132] The q-axis component of the dq-axis voltage component , do PI closed-loop regulation so that the q-axis component is 0 to obtain the grid voltage frequency, phase and voltage amplitude after phase locking, where PI stands for Proportional-Integral.

[0133] In other embodiments of the present application, the signal and The calculation formula is as follows:

[0134] ;

[0135] ;

[0136] In the formula, represents the orthogonal signal 1, represents the quadrature signal 2, Indicates the grid voltage, represents the complex frequency domain, represents the resonant frequency of the second-order generalized integral, Represents the closed-loop coefficient.

[0137] In other embodiments of the present application, the control unit 12, when adjusting the output of the four-quadrant rectifier module according to the grid voltage frequency, phase, voltage amplitude and intermediate DC voltage so that the primary voltage of the traction transformer of the train traction system is consistent with the grid voltage, is specifically used to:

[0138] According to the grid voltage frequency, phase, voltage amplitude and intermediate DC voltage, the output of the four-quadrant rectifier module is adjusted to control the primary voltage of the traction transformer of the train traction system, which rises according to the amplitude rise set value curve to keep the primary voltage of the traction transformer of the train traction system consistent with the grid voltage.

[0139] In other embodiments of the present application, the control unit 12 is also used to control the switching frequency of the four-quadrant rectifier module to a preset multiple of the rated operating frequency after the grid voltage passes through zero and the four-quadrant rectifier module of the train traction system is started at the same time; and control the four-quadrant rectifier modules corresponding to multiple secondary windings of the traction transformer to perform multiple carrier phase shifting.

[0140] In other embodiments of the present application, the four-quadrant rectifier module is n-fold, and the control unit 12, when executing the control of the four-quadrant rectifier modules corresponding to the multiple secondary windings of the traction transformer to perform multi-carrier phase shifting, is specifically used to:

[0141] The carrier phases of the n-fold four-quadrant rectifier modules are controlled to be staggered in sequence by the same π / n phase angle, so that the higher harmonics of the output voltage of each four-quadrant rectifier module are staggered.

[0142] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for actively suppressing the magnetizing inrush current of a train traction transformer, characterized in that: Applied to a train traction system, the method comprises: According to the train running condition, stabilizing the intermediate DC voltage of the intermediate DC circuit of the train traction system; The three-phase phase-locking method is constructed by using second-order generalized integral to obtain the grid voltage frequency, phase and voltage amplitude; Detecting the grid voltage, and when the grid voltage passes through a zero point, simultaneously starting the four-quadrant rectifier module of the train traction system, and adjusting the output of the four-quadrant rectifier module according to the grid voltage frequency, phase, voltage amplitude and the intermediate DC voltage, so that the primary voltage of the traction transformer of the train traction system is consistent with the grid voltage; Detecting the secondary component of the harmonic current of the four-quadrant rectifier module, and when the secondary component of the harmonic current reaches a set value, closing the circuit breaker of the train traction system; The step of adjusting the output of the four-quadrant rectifier module according to the grid voltage frequency, phase, voltage amplitude and the intermediate DC voltage so that the primary voltage of the traction transformer of the train traction system is consistent with the grid voltage includes: According to the grid voltage frequency, phase and voltage amplitude and the intermediate DC voltage, the output of the four-quadrant rectifier module is adjusted to control the primary voltage of the traction transformer of the train traction system to increase according to the amplitude increase setting value curve, so that the primary voltage of the traction transformer of the train traction system is consistent with the grid voltage; The amplitude rise setting value curve is specifically expressed as: ； in, is the primary voltage amplitude, is the initial value of the primary voltage, is the preset reference slope, α is a positive proportionality coefficient, i f2rms (t) is the magnitude of the second harmonic of the current of the four-quadrant rectifier module.

2. The method according to claim 1, characterized in that When the train operating condition is an over-phase condition, stabilizing the intermediate DC voltage of the intermediate DC circuit of the train traction system according to the train operating condition includes: When the train is in the over-phase condition, before the train enters the phase separation area, the circuit breaker is controlled to disconnect, the four-quadrant rectifier module stops working, the inverter module of the train traction system unloads the torque and enters the micro-braking mode to stabilize the intermediate DC voltage of the intermediate DC circuit of the train traction system.

3. The method according to claim 1, characterized in that When the train operating condition is a stationary condition, stabilizing the intermediate DC voltage of the intermediate DC circuit of the train traction system according to the train operating condition includes: When the train is in the stationary condition, the battery of the train traction system is controlled to provide energy to the auxiliary transformer module of the train traction system through the bidirectional charger of the train traction system to stabilize the intermediate DC voltage of the intermediate DC circuit of the train traction system.

4. The method according to claim 1, characterized in that The method of constructing a three-phase phase-locked mode using a second-order generalized integral to obtain the grid voltage frequency, phase and voltage amplitude includes: Using the second-order generalized integral, two mutually orthogonal signals are generated and ; According to the signal and , perform park transformation to obtain the voltage components of the dq axis of the three-phase synchronous rotating coordinate system; The q-axis component of the dq-axis voltage component , do PI closed-loop regulation so that the q-axis component is 0 to obtain the grid voltage frequency, phase and voltage amplitude after phase locking, where PI stands for Proportional-Integral.

5. The method as claimed in claim 4, characterized in that Signal and The calculation formula is as follows: ； ； In the formula, represents the orthogonal signal 1, represents the quadrature signal 2, Indicates the grid voltage, represents the complex frequency domain, represents the resonant frequency of the second-order generalized integral, Represents the closed-loop coefficient.

6. The method according to claim 1, characterized in that When the grid voltage passes through zero, after simultaneously starting the four-quadrant rectifier module of the train traction system, the method further includes: Controlling the switching frequency of the four-quadrant rectifier module to be a preset multiple of the rated operating frequency; The four-quadrant rectifier modules corresponding to the multiple secondary windings of the traction transformer are controlled to perform multi-carrier phase shifting.

7. The method as claimed in claim 6, characterized in that The four-quadrant rectifier module is n-fold, and the four-quadrant rectifier modules corresponding to the multiple secondary windings of the traction transformer are controlled to perform multi-carrier phase shifting, including: The carrier phases of the n-fold four-quadrant rectifier modules are controlled to be staggered in sequence by the same π / n phase angle, so that the higher harmonics of the output voltage of each fold of the four-quadrant rectifier modules are staggered.

8. An active suppression system for closing excitation inrush current of a train traction transformer, characterized in that: Applied to a train traction system, the active suppression system for closing excitation inrush current of the train traction transformer comprises: A processing unit, used for stabilizing an intermediate DC voltage of an intermediate DC circuit of the train traction system according to a train running condition; An acquisition unit is used to construct a three-phase phase-locked mode by using a second-order generalized integral to obtain a grid voltage frequency, phase and voltage amplitude; A control unit, configured to detect a grid voltage, and when the grid voltage passes through a zero point, simultaneously start a four-quadrant rectifier module of the train traction system, and adjust an output of the four-quadrant rectifier module according to the grid voltage frequency, phase, voltage amplitude and the intermediate DC voltage, so that a primary voltage of a traction transformer of the train traction system is consistent with the grid voltage; The control unit is further used to detect the secondary component of the harmonic current of the four-quadrant rectifier module, and when the secondary component of the harmonic current reaches a set value, close the circuit breaker of the train traction system; Wherein, the control unit, when executing the step of adjusting the output of the four-quadrant rectifier module according to the grid voltage frequency, phase, voltage amplitude and the intermediate DC voltage so that the primary voltage of the traction transformer of the train traction system is consistent with the grid voltage, is specifically used to: According to the grid voltage frequency, phase and voltage amplitude and the intermediate DC voltage, the output of the four-quadrant rectifier module is adjusted to control the primary voltage of the traction transformer of the train traction system to increase according to the amplitude increase setting value curve, so that the primary voltage of the traction transformer of the train traction system is consistent with the grid voltage; The amplitude rise setting value curve is specifically expressed as: ； in, is the primary voltage amplitude, is the initial value of the primary voltage, is the preset reference slope, α is a positive proportionality coefficient, i f2rms (t) is the magnitude of the second harmonic of the current of the four-quadrant rectifier module.

9. The active suppression system for closing excitation inrush current of the train traction transformer as claimed in claim 8, characterized in that: When the train operating condition is an over-phase condition, the processing unit, when executing the step of stabilizing the intermediate DC voltage of the intermediate DC circuit of the train traction system according to the train operating condition, is specifically used to: When the train is in the over-phase condition, before the train enters the phase separation area, the circuit breaker is controlled to disconnect, the four-quadrant rectifier module stops working, the inverter module of the train traction system unloads the torque and enters the micro-braking mode to stabilize the intermediate DC voltage of the intermediate DC circuit of the train traction system.

10. The active suppression system for closing excitation inrush current of a train traction transformer as claimed in claim 8, characterized in that: When the train operating condition is a stationary condition, the processing unit, when executing the step of stabilizing the intermediate DC voltage of the intermediate DC circuit of the train traction system according to the train operating condition, is specifically used to: When the train is in the stationary condition, the battery of the train traction system is controlled to provide energy to the auxiliary transformer module of the train traction system through the bidirectional charger of the train traction system to stabilize the intermediate DC voltage of the intermediate DC circuit of the train traction system.

11. The active suppression system for closing excitation inrush current of a train traction transformer as claimed in claim 8, characterized in that: The acquisition unit, when executing the method of constructing a three-phase phase-locked mode using a second-order generalized integral to obtain the grid voltage frequency, phase and voltage amplitude, is specifically used to: Using the second-order generalized integral, two mutually orthogonal signals are generated and ; According to the signal and , perform park transformation to obtain the voltage components of the dq axis of the three-phase synchronous rotating coordinate system; The q-axis component of the dq-axis voltage component , do PI closed-loop regulation so that the q-axis component is 0 to obtain the grid voltage frequency, phase and voltage amplitude after phase locking, where PI stands for Proportional-Integral.

12. The active suppression system for closing excitation inrush current of a train traction transformer as claimed in claim 11, characterized in that: Signal and The calculation formula is as follows: ； ； In the formula, represents the orthogonal signal 1, represents the quadrature signal 2, Indicates the grid voltage, represents the complex frequency domain, represents the resonant frequency of the second-order generalized integral, Represents the closed-loop coefficient.

13. The active suppression system for closing excitation inrush current of a train traction transformer as claimed in claim 8, characterized in that: The control unit is also used to control the switching frequency of the four-quadrant rectifier module to a preset multiple of the rated operating frequency after the grid voltage passes through zero and the four-quadrant rectifier module of the train traction system is started at the same time; and control the four-quadrant rectifier modules corresponding to the multiple secondary windings of the traction transformer to perform multiple carrier phase shifting.

14. The active suppression system for closing excitation inrush current of a train traction transformer as claimed in claim 13, characterized in that: The four-quadrant rectifier module is n-fold, and the control unit, when executing the control of the four-quadrant rectifier modules corresponding to the multiple secondary windings of the traction transformer to perform multi-carrier phase shifting, is specifically used to: The carrier phases of the n-fold four-quadrant rectifier modules are controlled to be staggered in sequence by the same π / n phase angle, so that the higher harmonics of the output voltage of each fold of the four-quadrant rectifier modules are staggered.

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