Over-phase control method of four-quadrant converter of rolling stock based on voltage source type

Abstract

The application provides a method for over-phase control of a four-quadrant converter of a voltage source type of a locomotive vehicle. The method comprises: when the locomotive vehicle detects entering a phase separation area, a digital controller of the four-quadrant converter in the vehicle receives an over-phase signal, and the four-quadrant converter outputs a converter blocking state signal; when the vehicle drives out of the phase separation area, the digital controller calculates a q-axis voltage component of a PCC point of a network side voltage in a two-phase rotating coordinate system, adjusts through an integral controller until a phase difference between a voltage vector and a tracking network side voltage is less than a set value range; the four-quadrant converter starts working, connects a DC voltage synchronous control loop, uses an error between the voltage vector and the tracking network side voltage to maintain synchronization and power transmission, adds a frequency additional damping, and outputs a PWM driving signal of the digital controller. The method can eliminate the phase difference in a restart process in a voltage source control mode, and well limits the inrush phenomenon.

Description

Technical Field

[0001] This invention relates to the field of locomotive and rolling stock converter control technology, and in particular to an over-phase control method for a voltage source type four-quadrant converter for locomotives and rolling stock. Background Technology

[0002] With the significant increase in the distance between power supply sections of newly built electrified railways (such as the Sichuan-Tibet Railway and the Strait Tunnel project, where the power supply section is over 100 kilometers), the line impedance has increased dramatically, leading to "multi-train sharing the same grid" operation scenarios. This results in the traction power supply system exhibiting typical characteristics of "high impedance, weak grid," or even "extremely weak grid." Simultaneously, in response to the national carbon peaking and carbon neutrality strategy, a large amount of distributed renewable energy such as photovoltaic and wind power will be integrated along and within electrified railway lines, irreversibly transforming the entire system into a new type of power system containing a large number of power electronic devices. Under the combined effect of these challenges, the traditional grid-following control mechanism based on the assumptions of a "strong grid" and "small proportion" is no longer applicable, leading to frequent "train-grid" coupling instability problems (such as low-frequency oscillations and high-frequency resonances), seriously threatening the safety of railway equipment and operations. Therefore, it is urgent to develop new control schemes more adaptable to the future environment of "high impedance, weak grid, and high-penetration power electronic devices."

[0003] In railway traction power supply systems, phase isolation zones, also known as de-energized zones or phase-separated zones, are set up at specific locations to isolate different power supply arms, reduce phase imbalance, and facilitate segmented maintenance and management of the power supply system. When a train passes through these de-energized zones, its pantograph temporarily disconnects from the power supply. The phase-separation process involves power outage shutdown (rapid shutdown of the four-quadrant converter, with the train coasting due to inertia or being maintained by auxiliary power), followed by restart and reconnection to the new power supply arm. The challenge of this reconnection process lies in the possibility of unknown voltage phase transitions between the preceding and following power supply arms. Therefore, extremely stringent requirements are placed on the control system: it must achieve rapid restart to shorten traction interruption time, effectively suppress the huge inrush current caused by phase transitions, and ultimately achieve stable grid connection.

[0004] In summary, the over-phase scenario is a unique and highly challenging high-dynamic operating condition of railway traction systems. It requires the control system of the train's four-quadrant converter to exhibit superior robustness and rapid response under extreme transient conditions to ensure the safe, efficient, and continuous operation of the train. This is precisely the key problem that traditional grid-type control schemes designed for distributed generator sets have not fully considered, and this invention aims to solve.

[0005] To effectively address the common "vehicle-grid" oscillation problem in train traction power supply systems, one existing low-frequency oscillation suppression method from a software control perspective includes:

[0006] (1) Impedance characteristic modeling and stability analysis of vehicle-to-grid coupling system:

[0007] This method first takes the CRH3 high-speed train as the research object, derives the impedance model of the high-speed railway vehicle-network coupling system, and conducts an in-depth analysis of the system stability based on the impedance ratio stability criterion and Bode plot, deriving the critical stability condition of the system. The study found that when multiple high-speed trains start under light load and the number increases, the amplitude-frequency characteristic curve of the system impedance ratio approaches 0dB, and the absolute value of the phase at the intersection frequency exceeds 180°, indicating that the system will experience low-frequency oscillations.

[0008] (2) Low-frequency oscillation suppression method based on virtual impedance:

[0009] To address system stability issues, this method improves the control strategy of the four-quadrant converter in the EMU by introducing a parallel virtual impedance at the EMU's input port. This virtual impedance effectively corrects the impedance characteristics of the load subsystem, thereby reshaping the impedance ratio of the entire vehicle-grid coupling system to meet the stability criterion, improving system robustness, and suppressing low-frequency oscillations.

[0010] (3) Design of the hardware and software co-architecture of the control system:

[0011] The proposed control strategy is mainly achieved by adjusting the inner loop control of the four-quadrant converter, injecting virtual impedance into the current loop in the form of feedback, avoiding additional hardware investment, and has the advantages of low cost and flexible implementation.

[0012] The disadvantages of the existing low-frequency oscillation suppression methods based on software control mentioned above include:

[0013] (1) Although this scheme attempts to introduce phase-locked loop optimization or feedforward technology to remedy the situation, it is still difficult to achieve stable and reliable operation in the railway traction environment where system parameters vary greatly and operating scenarios are complex. The stability of the network-following control mode of this scheme is poor and it is difficult to adapt to the high impedance railway power grid.

[0014] (2) The existing voltage source control structure of this scheme cannot handle the inrush current problem caused by phase jump, and it is slow to respond to high dynamic operation requirements, cannot meet the speed requirements in the restart process, and is difficult to cope with the special over-phase operation scenario of railways. Summary of the Invention

[0015] The embodiments of the present invention provide an over-phase control method for a voltage source type four-quadrant converter for locomotives and rolling stock, so as to effectively provide voltage support and optimize current control for the four-quadrant converter for locomotives and rolling stock, and ensure the safe, stable and efficient operation of trains.

[0016] To achieve the above objectives, the present invention adopts the following technical solution.

[0017] An over-phase control method based on a voltage source type four-quadrant converter for locomotives and rolling stock includes:

[0018] When the locomotive detects that it has entered the phase-splitting zone, the digital controller of the four-quadrant converter inside the locomotive receives the phase-splitting signal, the four-quadrant converter is in standby mode, and outputs the converter blocking status signal.

[0019] When the locomotive and rolling stock leave the phase separation zone, the digital controller determines the voltage based on the collected grid-side voltage. Perform coordinate transformation and calculate q-axis voltage component at the common connection point PCC in a two-phase rotating coordinate system ;

[0020] Before the four-quadrant converter restarts, the digital controller uses the q-axis voltage component. As input, it passes through the integral controller. Adjustments are made to make the voltage vector Tracking network side voltage until the voltage vector With tracking network side voltage The phase difference between them is less than the set numerical range;

[0021] When the four-quadrant converter starts working, the DC voltage synchronization control circuit is connected to obtain the actual value of the DC bus voltage. and reference value ,use and To maintain synchronization and power transfer by adjusting the error between them, add As a frequency-added damping, it outputs the PWM drive signal of the digital controller.

[0022] Preferably, when the locomotive detects entering the phase-splitting zone, the digital controller of the four-quadrant converter inside the locomotive receives the phase-splitting signal, the four-quadrant converter enters a standby state, and outputs a converter lockout state signal, including:

[0023] During the initialization phase, when the locomotive detects that it has entered the phase-splitting zone, the grid-side voltage of the locomotive is lost. The digital controller of the four-quadrant converter inside the locomotive receives the phase-splitting signal. The digital controller blocks the pulse width modulation (PWM) pulse of the four-quadrant converter, and the four-quadrant converter is in standby mode. The digital controller of the four-quadrant converter outputs the converter blocking status signal.

[0024] Preferably, when the locomotive or rolling stock leaves the phase-separation zone, the digital controller determines the voltage based on the collected grid-side voltage. Perform coordinate transformation and calculate q-axis voltage component at the common connection point PCC in a two-phase rotating coordinate system ,include:

[0025] When the locomotive and rolling stock leave the phase separation zone, the four-quadrant converter enters the startup preparation stage. The pantograph of the locomotive and rolling stock contacts the new power supply arm, and the control system collects the new grid-side voltage through the voltage transformer. When the digital controller of the four-quadrant converter of the locomotive and rolling stock receives the over-phase completion signal, the digital controller determines the phase based on the collected grid-side voltage. Perform coordinate transformation and calculate q-axis voltage component of the voltage at point PCC in a two-phase rotating coordinate system

[0026] Preferably, before the four-quadrant converter restarts, the digital controller uses the q-axis voltage component... As input, it passes through the integral controller. Adjustments are made to make the voltage vector Tracking network side voltage until the voltage vector With tracking network side voltage The phase difference between them is less than the set numerical range, including:

[0027] Before the four-quadrant converter of the locomotive and rolling stock is restarted, the control switch of the digital controller is switched to the pre-synchronization position, and the digital controller operates on the q-axis voltage component. As input, it passes through an integral controller. Adjust the internal rotation frequency. This makes the voltage vector Tracking network side voltage until the voltage vector With tracking network side voltage phase difference between Output phase angle synchronized with the power grid .

[0028] Preferably, when the four-quadrant converter starts working, it connects the DC voltage synchronization control circuit to obtain the actual value of the DC bus voltage. and reference value ,use and To maintain synchronization and power transfer by adjusting the error between them, add As a frequency-added damping, the PWM drive signal of the output digital controller includes:

[0029] When the voltage vector Tracking grid voltage After the phase difference is eliminated, the control system issues a pulse unlock command, the four-quadrant converter starts working, and the digital controller obtains the actual value of the DC bus voltage. and reference value Switch to DC voltage-based The steady-state control mode utilizes and To maintain synchronization and power transfer by adjusting the error between them, while adding As a frequency-added damping, it outputs the PWM drive signal of the digital controller.

[0030] As can be seen from the technical solutions provided by the embodiments of the present invention above, the present invention adopts a voltage source control mode, targeting the typical high impedance characteristics of railway traction systems. The proposed method no longer relies on the grid voltage as a reference, but instead enables the four-quadrant converter to actively construct a voltage source, improving the system's adaptability to weak grids and fundamentally enhancing the system's dynamic stability. The embodiments of the present invention propose a flexible switching synchronization method, which can effectively eliminate phase differences during restart and effectively limit inrush current phenomena.

[0031] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and will become apparent from the description or may be learned by practice of the invention. Attached Figure Description

[0032] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 A structural diagram of a railway traction power supply system provided in an embodiment of the present invention;

[0034] Figure 2 This is a schematic diagram of the main circuit of a railway traction power supply system provided in an embodiment of the present invention;

[0035] Figure 3 This is a control block diagram of a voltage source control mode provided in an embodiment of the present invention;

[0036] Figure 4 A schematic diagram illustrating the principle of surge generation provided in an embodiment of the present invention;

[0037] Figure 5 A schematic diagram of a phase synchronization adjustment process based on flexible switching of voltage source control mode is provided for an embodiment of the present invention;

[0038] Figure 6 This invention provides a small-signal model of a single-input single-output system derived through modeling in an embodiment of the invention. Detailed Implementation

[0039] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0040] Those skilled in the art will understand that, unless specifically stated otherwise, the singular forms “a,” “an,” “the,” and “the” used herein may also include the plural forms. It should be further understood that the term “comprising” as used in this specification means the presence of the stated features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. It should be understood that when we say an element is “connected” or “coupled” to another element, it can be directly connected or coupled to the other element, or there may be intermediate elements. Furthermore, “connected” or “coupled” as used herein can include wireless connections or couplings. The term “and / or” as used herein includes any and all combinations of one or more of the associated listed items.

[0041] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless defined as herein.

[0042] To facilitate understanding of the embodiments of the present invention, the following will provide further explanation and description with reference to the accompanying drawings and several specific embodiments. These embodiments do not constitute a limitation on the embodiments of the present invention.

[0043] To address the problems of traditional voltage source control in special railway operating scenarios, this invention proposes an over-phase control method for locomotive and rolling stock four-quadrant converters under voltage source control mode. This method proactively constructs voltage frequencies under weak grid conditions, improving system stability in such scenarios. Furthermore, it enhances the power synchronization speed of the traction four-quadrant converter during transient processes through small-signal modeling and parameter design. Finally, a flexible switching synchronization control method is proposed to eliminate the phase difference between the four-quadrant converter and the grid during restart synchronization, thereby resolving the inrush current problem during over-phase restart.

[0044] A structural diagram of a railway traction power supply system provided in this embodiment of the invention is shown below. Figure 1 As shown, the system first supplies power from the 220kV main grid to the 25kV railway contact network through a traction transformer, while also demonstrating the special scenario of crossing a phase-splitting zone in the power supply line. After the train receives power, the internal four-quadrant converter and inverter achieve efficient conversion of electrical energy, ultimately driving the traction motor to ensure train operation. In the diagram, 101 represents the 220kV main grid, 102 the traction transformer, 103 the four-quadrant rectifier, 104 the inverter, 105 the power supply line, and 106 the phase-splitting zone.

[0045] The flowchart of an over-phase control method based on a voltage source type four-quadrant converter for rolling stock provided in this embodiment of the invention is as follows: Figure 1 As shown, the processing steps include the following;

[0046] Step S10: When the locomotive detects that it has entered the phase-splitting zone, the digital controller of the four-quadrant converter inside the locomotive receives the phase-splitting signal, the four-quadrant converter is in standby mode, and outputs the converter blocking status signal.

[0047] During the initialization phase, when the locomotive detects entering the phase-splitting zone (de-energized zone), the grid-side voltage of the locomotive is lost. The digital controller of the four-quadrant converter inside the locomotive receives the phase-splitting signal, blocks the PWM (Pulse Width Modulation) pulses of the four-quadrant converter, and opens the main circuit breaker. At this time, the locomotive coasts due to inertia, the four-quadrant converter is in standby mode, and the digital controller of the four-quadrant converter outputs a converter lockout status signal.

[0048] Step S20: When the locomotive and rolling stock leave the phase separation zone, the digital controller determines the phase separation based on the collected grid-side voltage. Perform coordinate transformation and calculate The q-axis voltage component at the PCC (Point of Common Coupling) in a two-phase rotating coordinate system. .

[0049] During the restart preparation phase, the locomotive and rolling stock move out of the phase separation zone, and the pantograph of the locomotive and rolling stock makes contact with the new power supply arm. The control system collects the new grid-side voltage through voltage transformers. When the digital controller of the four-quadrant converter of the locomotive and rolling stock receives the over-phase completion signal, the digital controller begins to adjust the voltage based on the collected grid-side voltage. Perform coordinate transformation and calculate The components in the two-phase rotating coordinate system, especially the q-axis voltage component of the PCC point voltage. .

[0050] At this time, the four-quadrant converter of the locomotive and rolling stock is still in standby mode, and the voltage vector generated internally... With grid voltage There is an unknown phase difference.

[0051] Step S30: Synchronization technology based on flexible switching.

[0052] Activate before unlocking (restarting) the four-quadrant converter of the locomotive and rolling stock. Figure 5 The lower half of the control loop is the "pre-restart" control loop. At this point, the control switch is switched to the pre-synchronization position. The system uses the q-axis voltage component... As input, it passes through an integral controller. Adjustments are made to regulate the phase angle of the voltage vector E. The function of this integrator is to rapidly adjust the internal rotation frequency. This makes the voltage vector Tracking network side voltage until the voltage vector With tracking network side voltage phase difference between Output phase angle synchronized with the power grid .

[0053] Figure 5 An embodiment of the present invention provides a method for using an integral controller The schematic diagram shows the phase synchronization adjustment process, which is a closed-loop adjustment process based on the negative feedback principle. The specific processing steps include: the system first adjusts the q-axis component of the PCC point voltage, which reflects the phase deviation. (Input error signal to integral controller) By utilizing the zero steady-state error characteristic of the integrator, the internal rotating angular frequency is dynamically corrected, driving the internal voltage vector of the converter to rotate in space to actively approximate the grid voltage vector; as the two phases gradually align, The eventual convergence and stabilization at zero signifies that the internal coordinate system is completely aligned with the grid voltage vector, thus achieving zero-phase-difference synchronization and eliminating the physical basis for the inrush current generated during restart.

[0054] In existing voltage source control methods based on grid-connected architectures, the phase difference before restart cannot be eliminated due to the lack of a phase-locked loop (PLL), resulting in a huge inrush current. The flexible switching synchronization technology proposed in this invention solves this problem.

[0055] Step S40: Switch control mode to inrush-free grid connection.

[0056] When the voltage vector Tracking grid voltage After the phase difference is eliminated, the digital controller performs grid connection and mode switching operations, the control system issues a pulse unlock command, and the four-quadrant converter starts working. The system obtains the actual value of the DC bus voltage. and reference value Switch Figure 5 The control loop in step S30 is cut off, and the integral element in step S30 is disconnected. ), connect the DC voltage synchronization control circuit after "restart" (such as Figure 5 (As shown in the upper half). The system switches to DC voltage-based... The steady-state control mode utilizes and To maintain synchronization and power transfer by adjusting the error between them, while adding As a frequency-added damping, the output digital controller's final PWM drive signal ensures system stability. This flexible "synchronization first, switching later" control strategy ensures a smooth transition during restart, achieves inrush-free control for over-phase restarts, and retains the stability advantages of voltage source control under weak power grid conditions, ensuring stable operation of the converter. A schematic diagram of the main circuit of a railway traction power supply system provided in this embodiment of the invention is shown below. Figure 2 As shown, in railways, traction transformers are intentionally designed with a large inductance to act as the output filter of a four-quadrant converter. To improve stability in high-impedance railway power grid scenarios, this invention employs a voltage source control mode. A control block diagram of a voltage source control mode provided in this embodiment is shown below. Figure 3 As shown, a single-loop DC voltage synchronization control is used to generate the phase angle, and a reactive power loop is used to generate the voltage amplitude, which manifests externally as a voltage source. In the diagram, 301 represents the single-loop DC voltage synchronization control loop, and 302 represents the reactive power loop.

[0057] To address the inrush current problem caused by phase asynchrony in voltage source control mode, this invention provides a schematic diagram of inrush current generation as shown below. Figure 4 As shown.

[0058] (1)

[0059] In the formula, : Indicates the current flowing through the grid side. : Represents the voltage at point PCC, which is selected as the reference vector in the formula, and its phase angle is set to . . : Represents the voltage vector generated at the AC side port of the four-quadrant converter of locomotives and rolling stock. : Represents the port voltage vector of a four-quadrant converter With grid voltage vector The instantaneous phase difference between them. : Represents the fundamental angular frequency of the grid voltage. : Indicates the value of the leakage inductance or input filter inductance of the locomotive-side on-board transformer. : Indicates the equivalent inductance on the traction network side.

[0060] In phase-to-phase operation scenarios, various uncertainties (e.g., variable vehicle speed, uncertain segment lengths in the phase-splitting region, and potential phase imbalances between different power supply phases) lead to nondeterministic phase angles in the new connection segments. Therefore, the restart time V g The instantaneous phase difference between E and E is arbitrary, potentially ranging from -180° to 180°. This inherent unpredictability poses a severe challenge to the synchronous stability and transient control of grid-connected traction power systems, and can also cause significant inrush currents. The resulting transient dynamics may exceed the rated current by 3-5 times, posing a significant risk to semiconductor devices and DC bus capacitors in grid-connected converters.

[0061] To solve this problem, such as Figure 5 As shown, the problem is solved by adding an integral element to the control loop. The implementation involves two steps: first, PI (proportional-integral) regulation is used to eliminate the phase difference before restarting; then, after restarting, a DC voltage-based synchronization loop is activated and the integral element is disabled, thus achieving zero-phase-difference startup. This two-pronged approach not only suppresses inrush current but also maintains the grid formation control capability, thereby enhancing the grid support function of the railway power supply system.

[0062] To address the slow response issue of traditional solutions, this invention proposes a small-signal model for a single-input single-output system, as follows: Figure 6 As shown, by combining the dominant pole analysis method of closed-loop transfer function, the dominant parameters are identified by observing the effect of changing parameters on pole movement. The fast response capability of the system is improved by designing the active parameters.

[0063] This invention establishes a single-input single-output small-signal model for voltage source control mode. The fastness of parameter design is achieved by combining the small-signal model with the closed-loop transfer function-dominated pole analysis method. The operation of a four-quadrant converter is significantly affected by line impedance and parameters; therefore, virtual impedance control can be used to adjust the output impedance, as shown in equation (2).

[0064] (2)

[0065] : Represents virtual inductance parameters; : Represents virtual resistance parameters; : Represents the voltage vector sample value at the point of common coupling (PCC); : Represents the vector of electromotive force (or output voltage) generated inside the four-quadrant converter; : Represents the reference current vector generated by the virtual impedance control loop.

[0066] System main circuit model as follows Figure 2 As shown, the dynamic equations of the main circuit can be obtained.

[0067] (3)

[0068] superscript This indicates that the variable resides in the physical system coordinate system, distinguishing it from the rotating coordinate system c within the controller. The meanings of the other parameters have been explained above.

[0069] Substituting coordinate transformation (4) into formula (3) yields (5), and substituting (6) into formula (5) finally yields the main circuit equation (7) in the dq coordinate system.

[0070] (4)

[0071] (5)

[0072] (6)

[0073] (7)

[0074] : Represents the phase angle difference between the controller coordinate system and the actual grid voltage vector; : These represent the components of the grid-side current on the d-axis and q-axis, respectively.

[0075] By adding a small signal perturbation to the current and angle components, we can obtain equation (8). Applying the Laplace transform to equation (8) yields the relationship between the current increment and the angle increment (9).

[0076] (8)

[0077] (9)

[0078] The steady-state value of the current can be determined as shown in equation (10), and the steady-state value of the voltage can be determined as shown in equation (11). At the same time, by applying a small signal perturbation to equation (5), the first-order linear relationship between voltage and current can be obtained as shown in equation (12).

[0079] (10)

[0080] (11)

[0081] (12)

[0082] Substituting (9), (10), (11) and (12) into (13), we can obtain the relationship between power and angle in equation (14).

[0083] (13)

[0084] (14)

[0085] Using the voltage source control mode, the analytical expression for the DC voltage can be obtained as (15). Substituting (14) and (15) into the equations... Figure 6 Ultimately, a single-input single-output small-signal model of DC voltage is formed.

[0086] (15)

[0087] The open-loop transfer function (16) and closed-loop transfer function (17) can be obtained through the small-signal model. The closed-loop transfer function can be used for parameter design using the dominant pole analysis method.

[0088] (16)

[0089] (17)

[0090] The structure diagram for this section of formulas can be found in [link / diagram]. Figure 6 , : Represents the transfer function of a DC voltage controller; : indicates that the phase angle-power transfer function is derived from formula (14); That is, the power-voltage transfer function defined in formula (15).

[0091] In summary, the embodiments of this invention adopt a voltage source control mode, designed for the typical high impedance characteristics of railway traction systems. The proposed method no longer relies on the grid voltage as a reference, but instead enables the four-quadrant converter to actively construct a voltage source, improving the system's adaptability to weak grids and fundamentally enhancing the system's dynamic stability.

[0092] This invention presents a flexible switching synchronization method that can effectively eliminate the phase difference during the over-phase restart process and effectively limit inrush current.

[0093] This invention proposes a systematic parameter design strategy by establishing a small-signal model of a single-input single-output system and combining it with the closed-loop transfer function-dominated pole analysis method. This method not only enhances the theoretical basis for parameter design but also enables the system to exhibit greater robustness and faster response capabilities when facing traction power fluctuations and changing power grid conditions.

[0094] Those skilled in the art will understand that the accompanying drawings are merely schematic diagrams of one embodiment, and the modules or processes shown in the drawings are not necessarily essential for implementing the present invention.

[0095] As can be seen from the above description of the embodiments, those skilled in the art can clearly understand that the present invention can be implemented by means of software plus necessary general-purpose hardware platforms. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in various embodiments or some parts of the embodiments of the present invention.

[0096] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, for apparatus or system embodiments, since they are basically similar to method embodiments, the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments. The apparatus and system embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without creative effort.

[0097] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for over-phase control of a voltage source type four-quadrant converter for locomotives and rolling stock, characterized in that, include: When the locomotive detects that it has entered the phase-splitting zone, the digital controller of the four-quadrant converter inside the locomotive receives the phase-splitting signal, the four-quadrant converter is in standby mode, and outputs the converter blocking status signal. When the locomotive and rolling stock leave the phase separation zone, the digital controller determines the voltage based on the collected grid-side voltage. Perform coordinate transformation and calculate q-axis voltage component at the common connection point PCC in a two-phase rotating coordinate system ; Before the four-quadrant converter restarts, the digital controller uses the q-axis voltage component. As input, it passes through the integral controller. Adjustments are made to make the voltage vector Tracking network side voltage until the voltage vector With tracking network side voltage The phase difference between them is less than the set numerical range; When the four-quadrant converter starts working, the DC voltage synchronization control circuit is connected to obtain the actual value of the DC bus voltage. and reference value ,use and To maintain synchronization and power transfer by adjusting the error between them, add As a frequency-added damping, it outputs the PWM drive signal of the digital controller.

2. The method according to claim 1, characterized in that, When the locomotive detects entering the phase-splitting zone, the digital controller of the four-quadrant converter inside the locomotive receives the phase-splitting signal, the four-quadrant converter enters standby mode, and outputs a converter lockout status signal, including: During the initialization phase, when the locomotive detects that it has entered the phase-splitting zone, the grid-side voltage of the locomotive is lost. The digital controller of the four-quadrant converter inside the locomotive receives the phase-splitting signal. The digital controller blocks the pulse width modulation (PWM) pulse of the four-quadrant converter, and the four-quadrant converter is in standby mode. The digital controller of the four-quadrant converter outputs the converter blocking status signal.

3. The method according to claim 2, characterized in that, When the locomotive and rolling stock leave the phase separation zone, the digital controller determines the voltage based on the collected grid-side voltage. Perform coordinate transformation and calculate q-axis voltage component at the common connection point PCC in a two-phase rotating coordinate system ,include: When the locomotive and rolling stock leave the phase separation zone, the four-quadrant converter enters the startup preparation stage. The pantograph of the locomotive and rolling stock contacts the new power supply arm, and the control system collects the new grid-side voltage through the voltage transformer. When the digital controller of the four-quadrant converter of the locomotive and rolling stock receives the over-phase completion signal, the digital controller determines the phase based on the collected grid-side voltage. Perform coordinate transformation and calculate q-axis voltage component of the voltage at point PCC in a two-phase rotating coordinate system 4. The method according to claim 3, characterized in that, Before the four-quadrant converter restarts, the digital controller uses the q-axis voltage component... As input, it passes through the integral controller. Adjustments are made to make the voltage vector Tracking network side voltage until the voltage vector With tracking network side voltage The phase difference between them is less than the set numerical range, including: Before the four-quadrant converter of the locomotive and rolling stock is restarted, the control switch of the digital controller is switched to the pre-synchronization position, and the digital controller operates on the q-axis voltage component. As input, it passes through an integral controller. Adjust the internal rotation frequency. This makes the voltage vector Tracking network side voltage until the voltage vector With tracking network side voltage phase difference between Output phase angle synchronized with the power grid .

5. The method according to claim 4, characterized in that, The four-quadrant converter starts working, connects the DC voltage synchronization control circuit, and obtains the actual value of the DC bus voltage. and reference value ,use and To maintain synchronization and power transfer by adjusting the error between them, add As a frequency-added damping, the PWM drive signal of the output digital controller includes: When the voltage vector Tracking grid voltage After the phase difference is eliminated, the control system issues a pulse unlock command, the four-quadrant converter starts working, and the digital controller obtains the actual value of the DC bus voltage. and reference value Switch to DC voltage-based The steady-state control mode utilizes and To maintain synchronization and power transfer by adjusting the error between them, while adding As a frequency-added damping, it outputs the PWM drive signal of the digital controller.

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