A traction power supply soft starter, a traction power supply system and a control method

Abstract

This invention provides a traction power supply soft start device, a traction power supply system, and a control method. The primary side of the first transformer B1 is connected to the power supply line S via a first switch T1, and the secondary side of the first transformer B1 is connected to the AC terminal of the first converter N1. A DC power supply G is connected to the DC bus of the first converter N1. The power supply line S is connected to the three-phase power grid Q via a second switch T2. The first voltage transformer PT1 installed on the three-phase power grid Q and the second voltage transformer PT2 installed on the power supply line S are both connected to the main controller CCU. The main controller CCU is used to issue soft start commands to the controller of the first converter N1. The controller of the first converter N1 constructs a soft start drive strategy based on the soft start command. By adopting the soft start drive strategy, the traction transformer B, which is electrically connected to the power supply line S, will not generate an inrush current when the second switch T2 is closed.

Description

Technical Field

[0001] This invention relates to the field of traction power supply technology, and in particular to a traction power supply soft starter, traction power supply system and control method. Background Technology

[0002] In traction power supply technology, the reliable operation of the traction transformer is of paramount importance for the continuous power supply of the traction network. Under normal operation, the excitation current of the traction transformer is very small, generally not exceeding 2% to 5% of the rated current. However, when the traction transformer is closed under no-load conditions or when power is restored after external disconnection, an inrush current several times higher than the rated current is generated. This inrush current is mainly due to the saturation of the traction transformer core and the sudden voltage change at the moment of traction transformer closure, causing a sharp drop in the core permeability, which in turn reduces the circuit impedance and increases the excitation current. Inrush current easily causes malfunctions in the transformer differential protection, making accurate setting difficult. Furthermore, the inrush current contains a large number of harmonic components, forming circuits that increase electromagnetic losses and severely affect power quality, which is extremely detrimental to electrical equipment and can even damage it.

[0003] Currently, research on inrush current in traction transformers mainly focuses on how to identify inrush current to prevent differential protection from malfunctioning, while research on how to suppress inrush current in traction transformers is very limited. Summary of the Invention

[0004] To address the aforementioned problems, the first aspect of this invention is to propose a traction power supply soft-start device. The soft-start drive strategy constructed using this device ensures that no inrush current is generated when the traction transformer, electrically connected to the power supply line S, is engaged after the power supply line S is connected to the three-phase power grid Q. This invention is achieved through the following technical means:

[0005] A traction power supply soft starter includes a main controller CCU, a first switch T1, a first transformer B1, and a first converter N1. The primary side of the first transformer B1 is connected to a power supply line S through the first switch T1, and the secondary side of the first transformer B1 is connected to the AC terminal of the first converter N1. A DC power supply G is connected to the DC bus of the first converter N1, and the power supply line S is connected to a three-phase power grid Q through a second switch T2.

[0006] A first voltage transformer PT1 is installed on the three-phase power grid Q, and a second voltage transformer PT2 is installed on the power supply line S. Both the first voltage transformer PT1 and the second voltage transformer PT2 are connected to the main controller CCU.

[0007] The main controller CCU is used to issue a soft start command to the controller of the first converter N1. The controller of the first converter N1 constructs a soft start drive strategy based on the soft start command. The soft start drive strategy ensures that when the second switch T2 is closed, the traction transformer B, which is electrically connected to the power supply line S, will not generate an inrush current.

[0008] A second aspect of the present invention is to provide a method for controlling the above-mentioned traction power supply soft starter, comprising:

[0009] The main controller (CCU) sends a soft-start command to the controller of the first converter N1;

[0010] The main controller CCU controls the DC power supply G to supply power to the DC bus of the first converter N1 and closes the first switch T1;

[0011] The controller of the first converter N1 implements a soft-start drive strategy;

[0012] The controller of the first converter N1 drives the first converter N1 to generate a modulated voltage according to the soft-start drive strategy;

[0013] After generating the modulation voltage, the main controller CCU determines whether the closing condition of the second switch T2 has been met. If so, proceed to the next step.

[0014] The main controller CCU issues a command to close the second switch T2, or the main controller CCU controls the closure of the second switch T2.

[0015] Furthermore, the controller of the first converter N1 constructs a soft-start drive strategy including:

[0016] The controller of the first converter N1 acquires the voltage information of the first voltage transformer PT1 and locks in the phase, and obtains the effective voltage value of the three-phase power grid based on the voltage information of the first voltage transformer PT1. Frequency f and initial phase angle The controller of the first converter N1 obtains the voltage phase difference between the primary and secondary sides of the first transformer B1. ;

[0017] The controller of the first converter N1 is based on the effective voltage value. Frequency f, initial phase angle and voltage phase difference Constructing a reference modulation voltage .

[0018] Furthermore, the controller of the first converter N1 driving the first converter N1 to generate a modulation voltage according to the soft-start drive strategy includes: the controller of the first converter N1 driving the first converter N1 to generate a modulation voltage according to the reference modulation voltage. The first converter N1 is driven to generate a voltage modulated by the reference voltage. Consistent actual modulation voltage.

[0019] Furthermore, after generating the modulation voltage, the main controller CCU determines whether the closing condition of the second switch T2 has been met, including:

[0020] The main controller CCU obtains the voltage information of the power supply line S through the second voltage transformer PT2, and the main controller CCU obtains the voltage information of the three-phase power grid Q through the first voltage transformer PT1.

[0021] The main controller (CCU) determines whether the voltage of the power supply line S is synchronized with the voltage of the three-phase power grid Q. If so, the closing condition of the second switch T2 is met.

[0022] Furthermore, the controller of the first converter N1 determines the voltage effective value based on the voltage effective value. Frequency f, initial phase angle and voltage phase difference Constructing a reference modulation voltage Includes: constructing a reference modulation voltage according to formula (1) :

[0023] (1)

[0024] Where k is the primary-secondary voltage transformation ratio of the first transformer B1. This is the initial output voltage value of the first converter N1 during soft start. The output voltage of the first converter N1 is provided by Rise to The required time, t, is the actual operating time for the first converter N1 to generate the modulation voltage.

[0025] A third aspect of the present invention is to provide a traction power supply system, including the above-described traction power supply soft start device.

[0026] Furthermore, it also includes a second transformer B2, the primary side of which is connected to the power supply line S via a third switch T3, and the secondary side of which is connected to the contact network P via a fourth switch T4.

[0027] Furthermore, the DC terminal of the first converter N1 is connected to the contact network P via the fifth switch T5.

[0028] A fourth aspect of the present invention provides a control method for controlling the aforementioned traction power supply system, wherein, before the main controller (CCU) receives a traction power supply activation command, all switches T1 to T5 are disconnected, and the control method includes:

[0029] The main controller (CCU) receives the command to activate traction power supply;

[0030] Soft starting is performed according to the above method for controlling the traction power supply soft starter;

[0031] After the soft start is completed, the main controller (CCU) controls the system to enter the traction power supply mode.

[0032] Furthermore, when the traction power supply activation command received by the main controller CCU is an AC power supply command, before performing the soft start according to the above-described method for controlling the traction power supply soft start device, the method further includes closing the third switch T3. After the soft start is completed, the main controller CCU controls the entry into the traction power supply mode, including:

[0033] After closing the second switch T2, the main controller CCU sends a stop operation command to the controller of the first converter N1, and the first converter N1 stops working;

[0034] The main controller (CCU) controls the DC power supply G to stop supplying power to the DC bus of the first converter N1;

[0035] The main controller CCU issues a command to close the fourth switch T4, or the main controller CCU controls the closure of the fourth switch T4.

[0036] Furthermore, when the traction power supply activation command received by the main controller CCU is a DC power supply command, after the soft start is completed, the main controller CCU controls the entry into the traction power supply mode, including:

[0037] After the second switch T2 is closed, the main controller CCU sends a rectification operation command to the controller of the first converter N1, and the controller of the first converter N1 controls the first converter N1 to operate in rectification mode.

[0038] The main controller (CCU) controls the DC power supply G to stop supplying power to the DC bus of the first converter N1;

[0039] The main controller CCU issues a command to close the fifth switch T5, or the main controller CCU controls the closure of the fifth switch T5.

[0040] A fifth aspect of the present invention provides another control method for controlling the aforementioned traction power supply system, wherein, before the main controller CCU receives a traction power supply activation command, all switches from the first switch T1 to the fifth switch T5 are disconnected, and the control method includes:

[0041] The main controller (CCU) receives the traction power supply activation command and sends the traction power supply activation command information to the controller of the first converter N1.

[0042] Soft starting is performed according to the above method for controlling the traction power supply soft starter;

[0043] After the soft start is completed, the main controller (CCU) controls the system to enter the traction power supply mode.

[0044] Furthermore, when the traction power supply activation command received by the main controller CCU is an AC power supply command, before performing the soft start according to the above-described method for controlling the traction power supply soft start device, the method further includes closing the third switch T3. After the soft start is completed, the main controller CCU controls the entry into the traction power supply mode, including:

[0045] The controller of the first converter N1 detects whether the second switch T2 is in the closed state. If it is, the controller of the first converter N1 controls the first converter N1 to stop working.

[0046] The main controller (CCU) controls the DC power supply G to stop supplying power to the DC bus of the first converter N1;

[0047] The main controller CCU issues a command to close the fourth switch T4, or the main controller CCU controls the closure of the fourth switch T4.

[0048] Furthermore, when the traction power supply activation command received by the main controller CCU is a DC power supply command, after the soft start is completed, the main controller CCU controls the entry into the traction power supply mode, including:

[0049] The controller of the first converter N1 detects whether the second switch T2 is in the closed state. If it is, the controller of the first converter N1 controls the first converter N1 to switch to rectification mode.

[0050] The main controller (CCU) controls the DC power supply G to stop supplying power to the DC bus of the first converter N1;

[0051] The main controller CCU issues a command to close the fifth switch T5, or the main controller CCU controls the closure of the fifth switch T5.

[0052] The soft-start drive strategy constructed by the present invention using a soft-start device can prevent inrush current from being generated when the traction transformer electrically connected to the power supply line S is put into operation after the power supply line S is connected to the three-phase power grid Q. Attached Figure Description

[0053] Figure 1 This is a schematic diagram of a traction power supply soft starter according to an exemplary embodiment.

[0054] Figure 2 This is a flowchart illustrating a control method for a traction power supply soft starter according to an exemplary embodiment.

[0055] Figure 3 This is a schematic diagram of a traction power supply system according to an exemplary embodiment.

[0056] Figure 4This is a schematic diagram of another traction power supply system according to an exemplary embodiment.

[0057] Figure 5 This is a flowchart illustrating a traction power supply system control method according to an exemplary embodiment.

[0058] Figure 6 This is a flowchart illustrating another traction power supply system control method according to an exemplary embodiment. Detailed Implementation

[0059] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. The following description of specific embodiments is merely exemplary in nature and is not intended to limit the disclosed technology or its application and use.

[0060] In existing traction power supply technology, the traction transformers located in traction substations are directly connected to the three-phase power grid via switching devices. When traction power is needed, the switching devices are directly closed. At this time, the traction transformer will generate a sudden current exceeding several times its rated current due to voltage fluctuations, i.e., inrush current. The differential protection device may malfunction due to the inrush current. Therefore, traction power supply systems usually use inrush current identification technology to prevent differential protection malfunctions. However, this method cannot fundamentally solve the problem because differential protection identification technology is not always 100% accurate. If the differential protection device cannot accurately distinguish whether the sudden current is an inrush current or a fault current, there is still a possibility of differential protection malfunction. In addition, although the three-phase power grid capacity is usually large enough to tolerate the presence of inrush current, the presence of inrush current not only affects power quality but is also very detrimental to electrical equipment. Therefore, research on inrush current suppression technology for traction transformers in traction power supply systems is necessary.

[0061] Example 1

[0062] Given the existence of the aforementioned technical problems, such as Figure 1 As shown, this embodiment provides a traction power supply soft start device, including a main controller CCU, a first switch T1, a first transformer B1 and a first converter N1. The primary side of the first transformer B1 is connected to the power supply line S through the first switch T1, and the secondary side of the first transformer B1 is connected to the AC terminal of the first converter N1. A DC power supply G is connected to the DC bus of the first converter N1, and the power supply line S is connected to the three-phase power grid Q through a second switch T2.

[0063] A first voltage transformer PT1 is installed on the three-phase power grid Q, and a second voltage transformer PT2 is installed on the power supply line S. Both the first voltage transformer PT1 and the second voltage transformer PT2 are connected to the main controller CCU.

[0064] The main controller CCU is used to issue a soft start command to the controller of the first converter N1. The controller of the first converter N1 constructs a soft start drive strategy based on the soft start command. The soft start drive strategy ensures that when the second switch T2 is closed, the traction transformer B, which is electrically connected to the power supply line S, will not generate an inrush current.

[0065] In this embodiment, the first switch T1 and the first transformer B1 can be three-phase structures, the first converter N1 can be a three-phase rectifier, the three-phase AC port of the first converter N1 is connected to the secondary side of the first transformer B1, the DC terminal of the first converter N1 is connected to the DC power supply G, and the second switch T2 can be set as a circuit breaker.

[0066] In this embodiment, when the second switch T2 is closed, the traction transformer B, which is electrically connected to the power supply line S, will not generate inrush current. Specifically, when the second switch T2 is closed, the traction transformer B, which is electrically connected to the power supply line S, will not experience voltage surges or the voltage changes will be very small, thereby avoiding or greatly reducing inrush current. The method for constructing the soft-start drive strategy can be implemented according to the scheme described later. It should be noted that the traction transformer B in this embodiment is not an on-board transformer. On-board transformers draw power from the contact network, while the traction transformer B in this embodiment belongs to the traction power supply system. The traction transformer B draws power from the three-phase power grid (in this embodiment, the traction transformer B is electrically connected to the power supply line S, and the power supply line S is connected to the three-phase power grid Q through the second switch T2. When the second switch T2 is closed, the traction transformer B is equivalent to drawing power from the three-phase power grid Q), steps down the voltage, and then directly or indirectly provides power to the contact network.

[0067] In this embodiment, the first voltage transformer PT1 and the second voltage transformer PT2 can also be connected to the controller of the first converter N1. The controller of the first converter N1 can obtain the voltage information of the first voltage transformer PT1 directly through the first voltage transformer PT1, or indirectly through the main controller CCU. Similarly, the controller of the first converter N1 can obtain the voltage information of the second voltage transformer PT2 directly through the second voltage transformer PT2, or indirectly through the main controller CCU. After adopting the soft-start drive strategy, the main controller CCU can determine whether the closing condition of the second switch T2 has been met by using the voltage information obtained from the first voltage transformer PT1 and the second voltage transformer PT2. After the closing condition of the second switch T2 is met, when the second switch T2 is closed, the traction transformer B electrically connected to the power supply line S will not generate an inrush current.

[0068] Example 2

[0069] like Figure 2 As shown, this embodiment provides a method for controlling the traction power supply soft starter provided in Embodiment 1, including:

[0070] S1: The main controller CCU sends a soft start command to the controller of the first converter N1;

[0071] S2: The main controller CCU controls the DC power supply G to supply power to the DC bus of the first converter N1 and closes the first switch T1;

[0072] S3: The controller of the first converter N1 constructs a soft-start drive strategy;

[0073] S4: The controller of the first converter N1 drives the first converter N1 to generate a modulated voltage according to the soft-start drive strategy;

[0074] S5: After generating the modulation voltage, the main controller CCU determines whether the closing condition of the second switch T2 has been met. If so, proceed to the next step.

[0075] S6: The main controller CCU issues a command to close the second switch T2, or the main controller CCU controls the closure of the second switch T2.

[0076] Here, the DC power supply G can be an AC power supply plus a rectifier DC power supply, or other DC power supply methods. Generally, the main controller CCU or the internal control device of the DC power supply G controls the output of the DC power supply G to slowly raise the DC bus voltage of the first converter N1 to a specific voltage value. The controller of the first converter N1 constructs a soft-start drive strategy, which drives the first converter N1 to generate a modulated voltage. The first transformer B1 senses the modulated voltage generated by the first converter N1 onto the primary side. When the first switch T1 is closed... In this situation, power supply line S also becomes energized, causing the traction transformer electrically connected to power supply line S to also become energized. Based on this, if the closing conditions for the second switch T2 are met (e.g., the voltage of power supply line S is completely or nearly synchronized with the voltage of the three-phase power grid G, or the voltage difference between power supply line S and the three-phase power grid G ​​is within a certain range), closing the second switch T2 ensures that the traction transformer electrically connected to power supply line S will not experience voltage surges or will experience very small voltage changes. This avoids or greatly reduces inrush current, effectively preventing differential protection malfunctions, improving power quality, and extending the lifespan of electrical equipment. Here, the closing of the second switch T2 can be achieved through intelligent control by the main controller CCU, or manually by having the main controller CCU issue a closing command for the second switch T2.

[0077] Preferably, the controller of the first converter N1 constructs a soft-start drive strategy, i.e., step S3 includes:

[0078] S31: The controller of the first converter N1 obtains the voltage information of the first voltage transformer PT1 and locks in the phase, and obtains the effective voltage value of the three-phase power grid based on the voltage information of the first voltage transformer PT1. Frequency f and initial phase angle The controller of the first converter N1 obtains the voltage phase difference between the primary and secondary sides of the first transformer B1. ;

[0079] S32: The controller of the first converter N1 is based on the effective voltage value. Frequency f, initial phase angle and voltage phase difference Constructing a reference modulation voltage .

[0080] Preferably, the controller of the first converter N1 drives the first converter N1 to generate a modulation voltage according to a soft-start drive strategy, that is, step S4 includes: the controller of the first converter N1 drives the first converter N1 to generate a modulation voltage according to the reference modulation voltage. The first converter N1 is driven to generate a voltage modulated by the reference voltage. A consistent actual modulation voltage. In specific implementation, the controller of the first converter N1 may include multiple functional modules, such as a reference modulation voltage construction module that constructs the reference modulation voltage. Then the reference modulation voltage will be used. The input is fed into the modulation algorithm module (which may include the SVPWM algorithm module, SPWM algorithm module or other algorithm modules) to generate PWM drive pulses. At the same time, the PWM drive module is enabled. Under the drive of the PWM drive module, the first converter N1 generates the actual modulation voltage.

[0081] Preferably, after the modulation voltage is generated, the main controller CCU determines whether the closing condition of the second switch T2 has been met, including:

[0082] The main controller CCU obtains the voltage information of the power supply line S through the second voltage transformer PT2, and the main controller CCU obtains the voltage information of the three-phase power grid Q through the first voltage transformer PT1.

[0083] The main controller (CCU) determines whether the voltage of the power supply line S is synchronized with the voltage of the three-phase power grid Q. If so, the closing condition of the second switch T2 is met.

[0084] Preferably, the controller of the first converter N1 is based on the effective voltage value. Frequency f, initial phase angle and voltage phase difference Constructing a reference modulation voltage Includes: constructing a reference modulation voltage according to formula (1) :

[0085] (1)

[0086] Where k is the primary-secondary voltage transformation ratio of the first transformer B1. This is the initial output voltage value of the first converter N1 during soft start. The output voltage of the first converter N1 is provided by Rise to The required time, t, is the actual operating time for the first converter N1 to generate the modulation voltage.

[0087] Example 3

[0088] like Figure 3 and Figure 4 As shown, this embodiment provides a traction power supply system, including the traction power supply soft start device provided in Embodiment 1.

[0089] As a preferred option, such as Figure 3 As shown, this embodiment includes a second transformer B2. The primary side of the second transformer B2 is connected to the power supply line S via a third switch T3, and the secondary side of the second transformer B2 is connected to the contact network P via a fourth switch T4. Here, the second transformer B2 can be regarded as the traction transformer B mentioned in Embodiment 1. When the second transformer B2 supplies power to the contact network P as the traction transformer B, the traction power supply system provided in this embodiment operates in AC traction power supply mode. Here, the third switch T3 and the second transformer B2 can be a three-phase structure or a single-phase structure. When the negative sequence generated by the traction power supply system operating in AC traction power supply mode is not up to standard, negative sequence compensation can also be performed by the traction power supply soft starter device.

[0090] Preferably, the DC terminal of the first converter N1 is connected to the contact network P via the fifth switch T5. Here, during soft start, the DC bus of the first converter N1 is supplied with DC power through the DC power supply G, and the first converter N1 operates in inverter mode. After the soft start is completed, the DC power supply G stops supplying DC power. The first transformer B1 can be used as the traction transformer B mentioned in Embodiment 1, and the first converter N1 operates in rectification mode under the control of its controller, providing DC power to the contact network P. The traction power supply system provided in this embodiment operates in DC traction power supply mode. It should be noted that, in order to improve the utilization efficiency of the components and save equipment costs, this embodiment allows the first transformer B1 and the first converter N1 in the traction power supply soft start device to be directly used in DC traction power supply mode and supply DC power to the contact network P after soft start. In practical design, the traction power supply soft starter can be set up independently, and a separate DC power supply assembly can be set up. The DC power supply assembly consists of a sixth switch T6, a third transformer B3, a second rectifier N2, and a seventh switch T7. The primary side of the third transformer B3 is connected to the power supply line S through the sixth switch T6, and the secondary side of the third transformer B3 is connected to the AC terminal of the second rectifier N2. The DC terminal of the second rectifier N2 is connected to the contact network P through the seventh switch T7. After the traction power supply soft starter completes the soft start, the DC power supply assembly is controlled to supply DC power to the contact network P and the soft start is stopped.

[0091] Example 4

[0092] like Figure 5 As shown, this embodiment provides a control method for the traction power supply system provided in Embodiment 3. Before the main controller (CCU) receives the traction power supply activation command, all switches from the first switch T1 to the fifth switch T5 are open. The control method provided in this embodiment includes:

[0093] P1: The main controller (CCU) receives the command to activate traction power supply;

[0094] P2: Soft start is performed according to the traction power supply soft start device control method provided in Example 2;

[0095] P3: After the soft start is completed, the main controller CCU will control the system to enter the traction power supply mode.

[0096] Preferably, when the traction power supply activation command received by the main controller CCU is an AC power supply command, the soft start of the traction power supply soft start device control method according to Embodiment 2 further includes closing the third switch T3 before the soft start is performed. After the soft start is completed, the main controller CCU controls the device to enter the traction power supply mode, that is, step P3 includes:

[0097] P311: After closing the second switch T2, the main controller CCU sends a stop operation command to the controller of the first converter N1, and the first converter N1 stops working;

[0098] P312: The main controller CCU controls the DC power supply G to stop supplying power to the DC bus of the first converter N1;

[0099] P313: The main controller CCU issues a command to close the fourth switch T4, or the main controller CCU controls the closure of the fourth switch T4.

[0100] Preferably, when the traction power supply activation command received by the main controller CCU is a DC power supply command, after the soft start is completed, the main controller CCU controls the entry into the traction power supply mode, i.e., P3 includes:

[0101] P321: After closing the second switch T2, the main controller CCU sends a rectification operation command to the controller of the first converter N1, and the controller of the first converter N1 controls the first converter N1 to work in rectification mode.

[0102] P322: The main controller CCU controls the DC power supply G to stop supplying power to the DC bus of the first converter N1;

[0103] P323: The main controller CCU issues a command to close the fifth switch T5, or the main controller CCU controls the closure of the fifth switch T5.

[0104] Example 5

[0105] like Figure 6 As shown, this embodiment provides another control method for controlling the traction power supply system provided in embodiment 3. Before the main controller CCU receives the traction power supply activation command, all switches from the first switch T1 to the fifth switch T5 are open. The control method provided in this embodiment includes:

[0106] R1: The main controller CCU receives the traction power supply activation command and sends the traction power supply activation command information to the controller of the first converter N1;

[0107] R2: Soft start is performed according to the traction power supply soft start device control method provided in Example 2;

[0108] R3: After the soft start is completed, the main controller CCU will control the system to enter the traction power supply mode.

[0109] Preferably, when the traction power supply activation command received by the main controller CCU is an AC power supply command, the method for controlling the traction power supply soft start device according to Embodiment 2 further includes closing the third switch T3 before soft start. After the soft start is completed, the main controller CCU controls the entry into the traction power supply mode, including:

[0110] The controller of the first converter N1 detects whether the second switch T2 is in the closed state. If it is, the controller of the first converter N1 controls the first converter N1 to stop working.

[0111] The main controller (CCU) controls the DC power supply G to stop supplying power to the DC bus of the first converter N1;

[0112] The main controller CCU issues a command to close the fourth switch T4, or the main controller CCU controls the closure of the fourth switch T4.

[0113] Preferably, when the traction power supply activation command received by the main controller CCU is a DC power supply command, after the soft start is completed, the main controller CCU controls the entry into the traction power supply mode, including:

[0114] The controller of the first converter N1 detects whether the second switch T2 is in the closed state. If it is, the controller of the first converter N1 controls the first converter N1 to switch to rectification mode.

[0115] The main controller (CCU) controls the DC power supply G to stop supplying power to the DC bus of the first converter N1;

[0116] The main controller CCU issues a command to close the fifth switch T5, or the main controller CCU controls the closure of the fifth switch T5.

[0117] The above are merely preferred embodiments of the present invention. It should be noted that the above preferred embodiments should not be construed as limiting the present invention, and the scope of protection of the present invention should be determined by the scope defined in the claims. Persons skilled in the art will appreciate that improvements and modifications may be made without departing from the spirit and scope of the present invention, and such improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A traction power supply soft starter, characterized in that, It includes a main controller CCU, a first switch T1, a first transformer B1 and a first converter N1. The primary side of the first transformer B1 is connected to the power supply line S through the first switch T1, and the secondary side of the first transformer B1 is connected to the AC terminal of the first converter N1. A DC power supply G is connected to the DC bus of the first converter N1. The power supply line S is connected to the three-phase power grid Q through the second switch T2. A first voltage transformer PT1 is installed on the three-phase power grid Q, and a second voltage transformer PT2 is installed on the power supply line S. Both the first voltage transformer PT1 and the second voltage transformer PT2 are connected to the main controller CCU. The main controller CCU is used to send a soft start command to the controller of the first converter N1. The controller of the first converter N1 constructs a soft start drive strategy according to the soft start command. The soft start drive strategy can ensure that when the second switch T2 is closed, the traction transformer B, which is electrically connected to the power supply line S, will not generate an inrush current. The controller of the first converter N1 implements a soft-start drive strategy including: The controller of the first converter N1 acquires the voltage information of the first voltage transformer PT1 and locks in the phase, and obtains the effective voltage value U of the three-phase power grid based on the voltage information of the first voltage transformer PT1. rms The frequency f and the initial phase angle θ; the controller of the first converter N1 obtains the voltage phase difference Δθ between the primary and secondary sides of the first transformer B1; The controller of the first converter N1 is based on the effective voltage value U. rms The reference modulation voltage U is constructed using frequency f, initial phase angle θ, and voltage phase difference Δθ. ref ; The controller of the first converter N1 operates according to the reference modulation voltage U. ref The first converter N1 is driven to generate a voltage U that is modulated by the reference voltage. ref Consistent actual modulation voltage.

2. A control method for a traction power supply soft starter, characterized in that, The traction power supply soft start device includes a main controller CCU, a first switch T1, a first transformer B1, and a first converter N1. The primary side of the first transformer B1 is connected to the power supply line S through the first switch T1, and the secondary side of the first transformer B1 is connected to the AC terminal of the first converter N1. A DC power supply G is connected to the DC bus of the first converter N1. The power supply line S is connected to the three-phase power grid Q through a second switch T2. A first voltage transformer PT1 is installed on the three-phase power grid Q, and a second voltage transformer PT2 is installed on the power supply line S. Both the first voltage transformer PT1 and the second voltage transformer PT2 are connected to the main controller CCU. The control method includes: The main controller (CCU) sends a soft-start command to the controller of the first converter N1; The main controller CCU controls the DC power supply G to supply power to the DC bus of the first converter N1 and closes the first switch T1; The controller of the first converter N1 implements a soft-start drive strategy; The controller of the first converter N1 drives the first converter N1 to generate a modulated voltage according to the soft-start drive strategy; After generating the modulation voltage, the main controller CCU determines whether the closing condition of the second switch T2 has been met. If so, proceed to the next step. The main controller CCU issues a command to close the second switch T2, or the main controller CCU controls the closure of the second switch T2. The controller of the first converter N1 implements a soft-start drive strategy including: The controller of the first converter N1 acquires the voltage information of the first voltage transformer PT1 and locks in the phase, and obtains the effective voltage value U of the three-phase power grid based on the voltage information of the first voltage transformer PT1. rms The frequency f and the initial phase angle θ; the controller of the first converter N1 obtains the voltage phase difference Δθ between the primary and secondary sides of the first transformer B1; The controller of the first converter N1 is based on the effective voltage value U. rms The reference modulation voltage U is constructed using frequency f, initial phase angle θ, and voltage phase difference Δθ. ref ; The controller of the first converter N1 operates according to the reference modulation voltage U. ref The first converter N1 is driven to generate a voltage U that is modulated by the reference voltage. ref Consistent actual modulation voltage.

3. The method according to claim 2, characterized in that, After generating the modulation voltage, the main controller CCU determines whether the closing condition of the second switch T2 has been met, including: The main controller CCU obtains the voltage information of the power supply line S through the second voltage transformer PT2, and the main controller CCU obtains the voltage information of the three-phase power grid Q through the first voltage transformer PT1. The main controller (CCU) determines whether the voltage of the power supply line S is synchronized with the voltage of the three-phase power grid Q. If so, the closing condition of the second switch T2 is met.

4. The method according to claim 2, characterized in that, The controller of the first converter N1 is based on the effective voltage value U rms The reference modulation voltage U is constructed using frequency f, initial phase angle θ, and voltage phase difference Δθ. ref This includes: constructing the reference modulation voltage U according to formula (1) ref : Where k is the primary-secondary voltage transformation ratio of the first transformer B1, U0 is the initial output voltage of the first converter N1 during soft start, and T r The output voltage of the first converter N1 rises from U0 to The required time, t, is the actual operating time for the first converter N1 to generate the modulation voltage.

5. A traction power supply system, characterized in that, Includes the traction power supply soft starter as described in claim 1.

6. A traction power supply system according to claim 5, characterized in that, It also includes a second transformer B2, the primary side of which is connected to the power supply line S via a third switch T3, and the secondary side of which is connected to the contact network P via a fourth switch T4.

7. A traction power supply system according to claim 5 or 6, characterized in that, The DC terminal of the first converter N1 is connected to the contact network P via the fifth switch T5.

8. A control method for controlling the traction power supply system of claim 7, characterized in that, Before the main controller (CCU) receives the traction power supply activation command, all switches from the first switch T1 to the fifth switch T5 are open. The control method includes: The main controller (CCU) receives the command to activate traction power supply; Soft boot is performed according to any one of claims 2-4; After the soft start is completed, the main controller (CCU) controls the system to enter the traction power supply mode.

9. The control method according to claim 8, characterized in that, When the traction power supply command received by the main controller CCU is an AC power supply command, the method according to any one of claims 2-4 further includes closing the third switch T3 before performing the soft start. After the soft start is completed, the main controller CCU controls the entry into the traction power supply mode, including: After closing the second switch T2, the main controller CCU sends a stop operation command to the controller of the first converter N1, and the first converter N1 stops working; The main controller (CCU) controls the DC power supply G to stop supplying power to the DC bus of the first converter N1; The main controller CCU issues a command to close the fourth switch T4, or the main controller CCU controls the closure of the fourth switch T4.

10. The control method according to claim 8, characterized in that, When the traction power supply activation command received by the main controller CCU is a DC power supply command, after the soft start is completed, the main controller CCU controls the entry into the traction power supply mode, including: After the second switch T2 is closed, the main controller CCU sends a rectification operation command to the controller of the first converter N1, and the controller of the first converter N1 controls the first converter N1 to operate in rectification mode. The main controller (CCU) controls the DC power supply G to stop supplying power to the DC bus of the first converter N1; The main controller CCU issues a command to close the fifth switch T5, or the main controller CCU controls the closure of the fifth switch T5.

11. A control method for controlling the traction power supply system of claim 9, characterized in that, Before the main controller (CCU) receives the traction power supply activation command, all switches from the first switch T1 to the fifth switch T5 are open. The control method includes: The main controller (CCU) receives the traction power supply activation command and sends the traction power supply activation command information to the controller of the first converter N1. Soft boot is performed according to any one of claims 2-4; After the soft start is completed, the main controller (CCU) controls the system to enter the traction power supply mode.

12. The control method according to claim 11, characterized in that, When the traction power supply command received by the main controller CCU is an AC power supply command, the method according to any one of claims 2-4 further includes closing the third switch T3 before performing the soft start. After the soft start is completed, the main controller CCU controls the entry into the traction power supply mode, including: The controller of the first converter N1 detects whether the second switch T2 is in the closed state. If it is, the controller of the first converter N1 controls the first converter N1 to stop working. The main controller (CCU) controls the DC power supply G to stop supplying power to the DC bus of the first converter N1; The main controller CCU issues a command to close the fourth switch T4, or the main controller CCU controls the closure of the fourth switch T4.

13. The control method according to claim 11, characterized in that, When the traction power supply activation command received by the main controller CCU is a DC power supply command, after the soft start is completed, the main controller CCU controls the entry into the traction power supply mode, including: The controller of the first converter N1 detects whether the second switch T2 is in the closed state. If it is, the controller of the first converter N1 controls the first converter N1 to switch to rectification mode. The main controller (CCU) controls the DC power supply G to stop supplying power to the DC bus of the first converter N1; The main controller CCU issues a command to close the fifth switch T5, or the main controller CCU controls the closure of the fifth switch T5.

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