Railway flexible power supply device and automatic neutral section passing method thereof

Abstract

The application discloses a railway flexible power supply device and an automatic neutral section passing method thereof. The method comprises the following steps: detecting the train running state and the track section occupation state at a specified position of a track, generating a state signal and sending the state signal to a flexible neutral section passing control system; collecting voltage and current signals of a traction network and a neutral section, and sending the collected voltage and current signals to the flexible neutral section passing control system; pre-processing the voltage and current signals to obtain processed electric signals; switching the control mode of the railway flexible power supply device based on the state signal and the processed electric signals; and adjusting the voltage amplitude and phase of the neutral section according to the corresponding control mode, and smoothly switching the train power supply from the current power supply arm of the traction network to a target power supply arm. The method can realize flexible automatic neutral section passing, and solves the problems of temporary shutdown of the traction system, current and voltage impact and arc between the pantograph and the catenary caused by switching.

Description

Technical Field

[0001] This invention relates to the field of electrified railway traction power supply technology, and in particular to a railway flexible power supply device and its automatic phase transition method. Background Technology

[0002] By the end of 2024, my country's railway operating mileage reached 162,000 kilometers, with an electrification rate of 75.3%. While the electrification of railways has developed rapidly, it has also brought about many problems in terms of power supply quality and energy utilization efficiency.

[0003] First, electric locomotives, as single-phase, non-linear loads, inject a large amount of negative-sequence and harmonic currents into the traction power supply system and the public power grid. Negative-sequence currents, in turn, introduce additional losses into generators, causing rotor heating, additional vibrations, and other issues, seriously affecting the safe and stable operation of the power system. Harmonic currents introduce additional losses into power equipment, causing relay protection devices to malfunction and reducing the reliability of the power system. Therefore, the negative-sequence and harmonic problems in railway power supply systems have received widespread attention.

[0004] Furthermore, with the widespread adoption of new-generation AC drive electric locomotives, trains primarily rely on regenerative braking during braking. Especially on long gradients or sections of track with key stations, regenerative braking energy can reach over 30% of traction energy. Due to the single-phase, segmented power supply structure of railways, only a small portion of the regenerative braking energy is absorbed and utilized by other trains on the same power supply arm; the majority is returned to the public power grid as "waste electricity." Statistics show that railways return approximately 6 billion kilowatt-hours of "waste electricity" to the grid annually, resulting in economic losses amounting to billions of yuan. Currently, China lacks effective technical means to utilize this energy effectively. If suitable methods can be adopted to both recover and utilize regenerative braking energy and reduce negative sequence and harmonic currents, it would effectively reduce the energy consumption of the traction power supply system, improve power quality, and bring considerable economic benefits.

[0005] To address these issues, Japanese scholars pioneered a new generation of flexible traction power supply system for railways based on the Railway Power Conditioner (RPC), and have successfully implemented demonstration projects in Japan and Germany. Currently, adopting RPC-based flexible traction power supply technology is a crucial development direction for the future of railway power supply.

[0006] my country's electrified railway traction power supply network adopts a single-phase power frequency AC power supply mode. In order to mitigate the severe negative sequence impact of single-phase traction load on the power system, the traction power supply system implements a segmented current collection and phase sequence alternating access method, which dictates that there must be electrical phase separation in the traction power supply network. When an electric locomotive or electric multiple unit (EMU) passes through an electrical phase separation, it experiences a process of going from energized to de-energized and then back to energized. When the pantograph passes through the insulated section of two adjacent phases, it brings overvoltage and overcurrent problems. In severe cases, the pantograph-catenary system can experience continuous arcing, or even burn out the contact wire.

[0007] Common phase-crossing methods mainly include manual and automatic phase-crossing. Automatic phase-crossing can be further divided into vehicle-mounted automatic phase-crossing, pole-mounted automatic phase-crossing, and ground-based automatic phase-crossing. Existing ground-based automatic phase-crossing mainly uses a ground switch automatic switching scheme. This involves closing and opening a switch (mechanical or electronic) to select one of the two power supply arms at the neutral zone of the phase-crossing at a specific time, thus ensuring a supply voltage in the neutral zone and eliminating the need for train operation to cross the phase-crossing. However, in this scheme, to prevent short circuits between the two power supply arms during automatic phase-crossing switching, the switching actions must be sequential. This obviously results in a brief period of power deprivation in the neutral zone, and the voltage in the neutral zone experiences a phase change. This necessitates unloading or a short pause in the commonly used AC-DC-AC traction system to prevent overvoltage and overcurrent within the train's traction system. Furthermore, ground-based automatic phase-crossing is prone to overvoltage or overcurrent during the switching process. Therefore, how to achieve automatic phase transition of trains without power interruption without using mechanical switches or cutting off power supply has become an urgent technical problem to be solved in the field of traction power supply for electrified railways. Summary of the Invention

[0008] The purpose of this invention is to provide a flexible power supply device for railways and its automatic phase transition method, so as to solve the problem that the traction system needs to be briefly stopped due to the need for switching in the existing ground automatic phase transition scheme.

[0009] To achieve the above objectives, the technical solution adopted by this invention is: an automatic phase-splitting method based on a railway flexible power supply device, wherein the railway flexible power supply device includes a transformer unit, a voltage source converter unit, and a hybrid energy storage unit, the transformer unit includes three transformers, which are respectively connected to the first arm of the traction network, the neutral area of ​​the phase-splitting zone, and the second arm of the traction network, and the method includes the following steps:

[0010] S1: Detect the train running status and track section occupancy status at a designated location on the track, generate a status signal, and send the status signal to the flexible over-phase control system;

[0011] S2: Collect voltage and current signals of the traction network and the phase-splitting zone, and send the collected voltage and current signals to the flexible phase-splitting control system;

[0012] S3: Preprocess the voltage and current signals to obtain the processed electrical signal;

[0013] S4: Based on the status signal and the processed electrical signal, switch the control mode of the railway flexible power supply device;

[0014] S5: The railway flexible power supply device adjusts the voltage amplitude and phase of the phase separation zone according to the corresponding control mode, and smoothly switches the train power supply from the current power supply arm of the traction network to the target power supply arm.

[0015] This invention detects train status and electrical quantities to switch the control mode of the railway flexible power supply device. It can achieve smooth switching between power supply arms without the need for switching on / off or stopping the traction system, thus completely avoiding problems such as power outages, overvoltages, overcurrents, and pantograph-catenary arcing.

[0016] Furthermore, the train operating status includes the train's position and direction of travel, in order to accurately identify the phase transition stage and thus achieve adaptive switching of control modes.

[0017] Furthermore, in S2, detecting the voltage and current of the traction network and the phase-splitting zone includes:

[0018] The voltage of the first arm, the second arm, and the phase-separated zone of the traction network is detected by at least one voltage transformer.

[0019] The current in the first arm, the second arm, and the phase-splitting zone of the traction network is detected by at least one current transformer; at least two current transformers are used to detect the current in the phase-splitting zone in order to accurately obtain the electrical operating status of the system and provide a reliable data basis for control mode switching and voltage and current regulation.

[0020] Furthermore, the control modes of the railway flexible power supply device include at least one of the following: standby mode, first phase-crossing mode, second phase-crossing mode, energy replenishment mode, and no power supply mode. By defining multiple control modes, adaptive switching can be achieved according to the train's operating conditions and the traction network it is located in, taking into account multiple needs such as power quality management, power regulation, and no power supply, thus significantly improving the system's flexibility and applicability.

[0021] Furthermore, in S4, the process based on the state signal and the processed electrical signal specifically includes:

[0022] When the train has not passed the phase separation zone or has left the phase separation zone, the railway flexible power supply device is switched to standby mode;

[0023] When the train enters the phase-splitting zone in the first direction and the first and second arms of the traction network have sufficient energy, the railway flexible power supply device is switched to the first phase-splitting mode.

[0024] When the train enters the phase-splitting zone in the second direction and the first and second arms of the traction network have sufficient energy, the railway flexible power supply device is switched to the second phase-splitting mode.

[0025] By automatically switching the mode of the railway flexible power supply device according to the train's position, direction and traction network energy status, without manual operation, it achieves smooth, continuous and reliable phase transition control under sufficient energy conditions, thereby improving the overall operating efficiency and safety of the system.

[0026] Furthermore, the control modes for switching railway flexible power supply devices also include:

[0027] When the train is in the phase-separation zone and the first and second arms of the traction network are insufficient in energy, the railway flexible power supply device will be switched to the energy replenishment mode.

[0028] When the train is in the phase-separation zone and the first and second arms of the traction network are without power, the railway flexible power supply device is switched to the power-off mode. It can automatically switch the control mode when the traction network is short of energy or without power, and rely on hybrid energy storage to maintain power supply, ensuring that the train passes through the phase separation without interruption or shutdown, and improving the reliability and adaptability of the system under complex working conditions.

[0029] Furthermore, the phase separation zone includes a first transition zone, a central zone, and a second transition zone, and S5 includes smoothly switching the train power supply from the first arm to the second arm of the traction network, specifically including:

[0030] When the railway flexible power supply device is in standby mode and the train has not entered the phase-splitting zone, the output voltage of the railway flexible power supply device is... , among which, U a The voltage of the first arm of the traction net;

[0031] When the railway flexible power supply device is in the first over-phase mode and the train travels to the first transition zone, the railway flexible power supply device begins to output current and increases to I. a The voltage phase remains unchanged, where I a Equal to the actual current of the train;

[0032] When the railway flexible power supply device is in the first over-phase mode and the train travels to the first preset point in the neutral zone, the railway flexible power supply device uses U b To adjust the reference, the neutral voltage is gradually amplitude-shifted and phase-shifted.

[0033] When the railway flexible power supply device is in the first phase-over mode and the train travels to the second transition zone, the railway flexible power supply device completes phase shifting, and the neutral zone voltage... Simultaneously, the output current of the railway flexible power supply device gradually decreases to zero, and the train receives current from the second arm, wherein U b The voltage of the second arm of the traction net;

[0034] When the railway flexible power supply device is in standby mode and the train leaves the phase separation zone, the output voltage of the railway flexible power supply device is... .

[0035] By dividing the phase-splitting zone into a first transition zone, a central zone, and a second transition zone, and combining the train's location and control mode, the system adaptively performs voltage maintenance, progressive amplitude modulation phase shifting, and dynamic adjustment of output current. This allows for precise matching of the train's power supply needs at different phase-splitting stages, achieving fully automatic and smooth switching from the first arm to the second arm of the traction network. This ensures stable and uninterrupted phase-splitting throughout the entire process.

[0036] Furthermore, the phase separation zone includes a first transition zone, a central zone, and a second transition zone, and S5 includes smoothly switching the train power supply from the second arm of the traction network to the first arm, specifically including:

[0037] When the railway flexible power supply device is in standby mode and the train has not entered the phase-splitting zone, the output voltage of the railway flexible power supply device is... , among which, U b The voltage of the second arm of the traction net;

[0038] When the railway flexible power supply device is in the second over-phase mode and the train travels to the second transition zone, the railway flexible power supply device begins to output current and increases to I. b The voltage phase remains unchanged, where I b Equal to the actual current of the train;

[0039] When the railway flexible power supply device is in the second over-phase mode and the train travels to the second preset point in the neutral zone, the railway flexible power supply device uses U a To adjust the reference, the neutral voltage is gradually amplitude-shifted and phase-shifted.

[0040] When the railway flexible power supply device is in the second phase-shifting mode and the train travels to the first transition zone, the railway flexible power supply device completes phase shifting, and the neutral zone voltage... Simultaneously, the output current of the railway flexible power supply device gradually decreases to zero, and the train receives current from the first arm, wherein U a The voltage of the first arm of the traction net;

[0041] When the railway flexible power supply device is in standby mode and the train leaves the phase separation zone, the output voltage of the railway flexible power supply device is... Considering the phase transition requirements of trains traveling in both directions, the system enables adaptive and smooth power switching in both the up and down directions, ensuring a stable and continuous phase transition process in different travel directions.

[0042] Based on the same concept, the present invention also provides a railway flexible power supply device, the device comprising a transformer unit, a voltage source converter unit and a hybrid energy storage unit;

[0043] The transformer unit includes a first transformer, a second transformer, and a third transformer. The primary side of the first transformer is connected to the first arm of the traction network, the primary side of the second transformer is connected to the second arm of the traction network, and the primary side of the third transformer is connected to the neutral zone.

[0044] The voltage source converter unit includes a first converter, a second converter, and a third converter. The AC side of the first converter is connected to the secondary side of the first transformer, the AC side of the second converter is connected to the secondary side of the second transformer, and the AC side of the third converter is connected to the secondary side of the third transformer.

[0045] The DC sides of the first converter, the second converter, and the third converter are connected together to form a common DC bus;

[0046] The hybrid energy storage unit is connected in parallel with the common DC bus via a bidirectional DC / DC converter.

[0047] This invention improves the structure of the RPC system with hybrid energy storage to construct a new type of flexible power supply system for railways. While retaining traditional functions such as regenerative braking energy transfer, storage, and comprehensive power quality compensation, it adds a flexible automatic phase transition function for trains. This achieves integrated power quality management, efficient energy utilization, and automatic phase transition, expanding the functional boundaries of the system and improving the overall performance and practicality of the railway traction power supply system.

[0048] Furthermore, the composition of the railway flexible power supply device under different control modes includes:

[0049] In standby mode, the third converter is in standby mode, while the first converter, the second converter, and other units remain in operation.

[0050] In the first phase-splitting mode, the second converter and the third converter constitute a flexible phase-splitting device;

[0051] In the second phase-splitting mode, the first converter and the third converter constitute a flexible phase-splitting device;

[0052] In the energy replenishment mode, the hybrid energy storage unit releases electrical energy and forms a flexible phase-splitting device with the first converter and the third converter or the second converter and the third converter.

[0053] In the no-power supply mode, the hybrid energy storage unit releases electrical energy and forms a flexible phase-splitting device with the third converter.

[0054] Flexible phase-splitting device configurations are designed to adapt to different operating conditions, and the working states of each converter and hybrid energy storage unit are rationally allocated to achieve optimized allocation and efficient utilization of device resources.

[0055] Compared with existing technologies, the beneficial effects of this invention are as follows: By designing a flexible power supply device for railways and proposing a corresponding automatic phase transition method, this invention can achieve automatic switching of power supply status without the need for mechanical (or electrical) switch opening and closing operations, fundamentally avoiding current and voltage surges and pantograph-catenary arcing problems caused by switch operations; based on the train's driving position, driving direction, and traction network electrical status, it adaptively adjusts and achieves a smooth and uninterrupted transition of power supply in the phase transition zone through progressive amplitude modulation, phase shifting, and dynamic current control; at the same time, it integrates multiple working modes such as standby, bidirectional phase transition, energy replenishment, and power supply without power, which can comprehensively cover complex working conditions such as normal power supply, insufficient energy, and power grid failure, ensuring that the train can achieve flexible automatic phase transition without interruption, stability, and reliability throughout the entire process, greatly improving the safety, adaptability, and operational stability of the traction power supply system. Attached Figure Description

[0056] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only one embodiment of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0057] Figure 1 This is a flowchart of the automatic phase-crossing method based on a railway flexible power supply device in an embodiment of the present invention;

[0058] Figure 2 This is a typical schematic diagram of a railway power regulator;

[0059] Figure 3 This is a schematic diagram of a railway power regulator system equipped with hybrid energy storage;

[0060] Figure 4 This is a schematic diagram of a railway flexible power supply device according to an embodiment of the present invention. Detailed Implementation

[0061] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0062] To make the technical content of this invention easier to understand, the key technical terms in the solution are explained below:

[0063] Flexible power supply: The voltage, current, phase and other parameters of the power system are flexibly adjusted through power electronics, microelectronics and control technology.

[0064] Regenerative braking: The energy generated during braking is fed back to the traction network for use by other trains starting or accelerating.

[0065] Flexible automatic phase transition: Based on power electronics and its control technology, it enables trains to smoothly pass through electrical phase transitions without power interruption by precisely controlling the traction network power in the phase transition zone.

[0066] Example 1

[0067] like Figure 1 As shown in the figure, this invention proposes an automatic phase-crossing method based on a railway flexible power supply device. A typical railway power regulator schematic diagram is shown below. Figure 2 As shown, the RPC consists of two voltage source inverters sharing a DC bus and two coupled step-down transformers. The RPC can flexibly adjust the active power and power quality. Its main function is to realize the mutual transfer of active power between the two power supply arms and to realize the independent compensation of reactive power and harmonic current between the two power supply arms.

[0068] When RPC is used at the end of a traction power supply section, it enables the sharing of active power between two traction sections, improving the utilization rate of regenerative braking energy and reducing the maximum demand and electricity cost of adjacent traction substations. When RPC is used at a traction substation, it not only balances the active power of the two power supply arms and reduces negative sequence and harmonic currents, but also stabilizes the grid voltage of the power supply arms. Adding energy storage units to the DC side of the RPC can further improve the utilization rate of regenerative braking energy and reduce the maximum demand. If RPC is used simultaneously at the beginning and end of a power supply section, it can effectively improve the power supply quality of the entire line, increase the utilization rate of regenerative braking energy, and reduce basic electricity costs, thereby reducing railway operating costs and improving railway economic efficiency.

[0069] Because the DC link of the RPC can provide a good interface for the energy storage unit, the RPC equipped with the energy storage unit can realize the storage and reuse of regenerative braking energy, effectively reducing the electricity cost of the transformer's maximum demand and traction load consumption. Figure 3A railway back-to-back hybrid energy storage system based on an RPC structure as an energy conversion unit is shown. The hybrid energy storage unit is connected at the intermediate DC link of the system. This structure can realize functions such as regenerative braking energy transfer, storage and comprehensive power quality compensation, but it does not solve the problem of automatic train phase transition.

[0070] To address the shortcomings of existing RPC devices in automatically controlling phase transitions for trains, this invention proposes an automatic phase transition method based on a railway flexible power supply device with power quality compensation, regenerative braking energy recovery and transfer functions. This method, considering the train's position, direction, and traction network power supply status, achieves seamless, shock-free, and uninterrupted automatic phase transitions for trains through multi-mode adaptive switching and gradual voltage and current adjustment, effectively overcoming the deficiencies of existing traction power supply phase transition control schemes. The method includes the following steps:

[0071] S1: The train position identification system detects the train running status and track section occupancy status at a designated position on the track, generates a status signal, and sends the status signal to the flexible over-phase control system. The train running status includes the train's driving position and driving direction.

[0072] The train position recognition system mainly consists of wheel sensors and a signal preprocessing unit, such as... Figure 4 As shown, the wheel sensors include four wheel sensors CG1, CG2, CG3, and CG4 located at points A, D1, D, and G respectively. These sensors are used to detect whether a train has arrived at a designated location on the track, the train's direction of travel, and whether the track detection zone is occupied or cleared. The processed signal status is then sent to the flexible phase-crossing control system.

[0073] S2: The traction network and phase-splitting area voltage and current measurement system collects the voltage and current of the traction network and phase-splitting area in real time, and sends the collected voltage and current signals to the flexible phase-splitting control system. The flexible phase-splitting control system uses the voltage and current signals of the traction network and phase-splitting area as the control input, providing data support for the subsequent realization of smooth phase-splitting without power interruption of the train.

[0074] like Figure 4As shown, taking the illustrated travel direction as an example, voltage transformers PT1, PT2, and PT3 are used to detect the voltage of power supply arm A, the neutral section, and power supply arm B, respectively, providing reference input for the flexible phase-crossing control system. Current transformer CT1 indirectly obtains the train operating current by collecting the current signal from traction power supply arm A and transmits the current signal to the flexible phase-crossing control system, providing data support for the smooth power transfer between power supply arm A and the phase-crossing device. Current transformer CT2 indirectly obtains the train operating current by collecting the neutral section current, providing a basis for switching the flexible phase-crossing control mode. Current transformer CT3 indirectly obtains the train operating current by measuring the neutral section current, providing a current signal to the flexible phase-crossing device control system to complete the smooth power transfer between power supply arm A and the phase-crossing device. Current transformer CT4 indirectly obtains the train operating current by measuring the current from traction power supply arm B, providing a basis for switching the flexible phase-crossing control mode. When the train travels in the opposite direction, the detection functions of current transformers CT2 and CT3 are interchanged accordingly, and the system can adaptively complete the flexible phase-crossing control under reverse conditions.

[0075] S3: Preprocess the voltage and current signals to obtain processed electrical signals. Preprocessing includes signal filtering, electrical isolation, signal amplification and attenuation, amplitude correction, and signal conditioning before analog-to-digital conversion to remove interference noise in the signal and obtain a stable and reliable electrical signal.

[0076] S4: Based on the aforementioned status signal and the processed electrical signal, switch the control mode of the railway flexible power supply device. The control mode of the railway flexible power supply device includes at least one of the following: standby mode, first phase-crossing mode, second phase-crossing mode, power replenishment mode, and no power supply mode. Specifically, switching the control mode of the railway flexible power supply device includes:

[0077] like Figure 4 As shown in the diagram, taking the direction of travel as an example, when the train has not passed the phase separation zone or has left the phase separation zone, that is, the train has not reached point B or has passed point F, the railway flexible power supply device will be switched to standby mode.

[0078] When the train enters the phase-splitting zone in the direction shown in the diagram, that is, when the train reaches point B and the A and B arms of the traction network have sufficient energy, the railway flexible power supply device will be switched to the first phase-splitting mode.

[0079] When the train enters the phase-splitting zone in the opposite direction to the direction of travel shown in the diagram, that is, when the train travels to point F and the A and B arms of the traction network have sufficient energy, the railway flexible power supply device will be switched to the second phase-splitting mode.

[0080] In addition, because the railway flexible power supply device has RPC and hybrid energy storage units, it can ensure a continuous and stable power supply to the phase separation area when the power supply arm of the traction network is insufficient or completely de-energized, thus ensuring that the train passes through the phase separation area safely, smoothly, and without power outages.

[0081] Specifically, when the train is in the phase separation zone, that is, when the train is between point B and point F, and the A and B arms of the traction network are insufficient, the railway flexible power supply device will be switched to the energy supplement mode.

[0082] When the train is in the phase separation zone and the A and B arms of the traction network are de-energized, the railway flexible power supply device will be switched to the de-energized mode.

[0083] S5: The railway flexible power supply device adjusts the voltage amplitude and phase of the phase-splitting zone according to the corresponding control mode, smoothly switching the train power supply from one arm of the traction network to the other. The control mode is the working mode determined by the flexible phase-splitting control system in combination with status signals (including train travel position), traction network power supply status, and processed electrical signals; the railway flexible power supply device adjusts the voltage amplitude and phase of the phase-splitting zone according to the control mode that matches the train position, realizing a smooth voltage switch between the two power supply arms of the traction network.

[0084] like Figure 4 As shown, the phase separation zone includes a transition zone and a neutral zone. In electrified railways, the phase separation section is a section of unenergized overhead contact line conductor, also known as the neutral section. There is a break between the neutral section and the two overhead contact line power supply arms on either side: the entry break and the exit break. These two breaks electrically isolate the power supply arms on both sides of the neutral section. At the break position, both the power supply arm conductor and the phase separation conductor exist simultaneously in the rail direction, with their horizontal spacing generally less than that of the train pantograph. In this state, the train pantograph can simultaneously connect to both the power supply arm and the phase separation conductor; this is called the transition zone.

[0085] When the train Figure 4 When traveling in the indicated direction, the basic timing sequence of the output voltage amplitude modulation phase shift of the flexible phase-splitting device specifically includes:

[0086] When the train arrives at point A but has not yet entered the phase-separation zone, the railway flexible power supply device is in standby mode, and the output voltage is [not specified]. , among which, U a The voltage of arm A of the traction network;

[0087] When the train reaches point B, i.e., when it has traveled to transition zone A, the railway flexible power supply device is in the first phase-crossing mode. The train current is gradually transferred to be provided by the flexible phase-crossing device, and the railway flexible power supply device begins to output current, which increases to I before reaching point C. a The train current is entirely supplied by a flexible phase-splitting device, and the voltage phase remains constant. Specifically, I...a Equal to the actual current of the train;

[0088] When the train reaches the neutral zone and arrives at point D, the railway flexible power supply device is still in the first phase-crossing mode. The railway flexible power supply device uses U... b To adjust the reference, the neutral voltage is gradually amplitude-shifted and phase-shifted.

[0089] Point D is located within the neutral zone, after the end of transition zone A and before the beginning of transition zone B. This ensures that the train's pantograph is completely out of the power supply range of power supply arm A, avoiding electrical interference with arm A during amplitude modulation and phase shifting. Point D corresponds to the position where CT2 detects stable current but CT3 has not yet detected current. This means the train has traveled into the neutral zone and has sufficient electrical buffer distance from both transition zones to ensure reliable timing triggering logic for amplitude modulation and phase shifting. The distance from point D to transition zone B must meet the time requirement for the flexible phase-shifting device to complete amplitude modulation and phase shifting. Specifically, the time it takes for the train to travel from point D to transition zone B must be greater than the time required for the device to adjust the voltage from the phase / amplitude of arm A to that of arm B. b The response time is optimized to prevent power outages or surges caused by the voltage not being fully adjusted when the train arrives at transition zone B.

[0090] When the train reaches point E, that is, when the train has traveled to transition zone B, the railway flexible power supply device is still in the first phase-shifting mode. The railway flexible power supply device completes phase shifting, and the neutral zone voltage... Meanwhile, the output current of the railway flexible power supply device gradually decreases to zero, and the train receives current from arm B, where U b The voltage of arm B of the traction network;

[0091] When the train arrives at point F and leaves transition zone B, the railway flexible power supply device is in standby mode, and the output voltage of the railway flexible power supply device is [not specified]. The RPC and energy storage system then begin operation.

[0092] When the train enters the neutral section from the A arm, the converter and the series transformer windings work together to transform the form of electrical energy, generating a voltage with the same amplitude and phase as the A arm. The train can enter without interrupting power. Then, through amplitude modulation and phase shifting by the converter, the voltage in the neutral section is gradually made to have the same amplitude and phase as the voltage in the B arm, so as to achieve uninterrupted power transmission and phase separation for the train.

[0093] When the train Figure 4 When traveling in the opposite direction shown, the basic timing sequence of the output voltage amplitude modulation phase shift of the flexible phase-splitting device specifically includes:

[0094] When the train arrives at point G but has not yet entered the phase-separation zone, the railway flexible power supply device is in standby mode, and the output voltage is [not specified]. , among which, U bThe voltage of arm B of the traction network;

[0095] When the train reaches point F, i.e., when it has reached transition zone B, the railway flexible power supply device is in the second phase-crossing mode. The train current is gradually transferred to be provided by the flexible phase-crossing device, and the railway flexible power supply device begins to output current, which increases to I before reaching point E. b The train current is entirely supplied by a flexible phase-splitting device, and the voltage phase remains constant. Specifically, I... b Equal to the actual current of the train;

[0096] When the train reaches the neutral zone and arrives at point D1, the railway flexible power supply device is still in the second over-phase mode. The railway flexible power supply device uses U... a To adjust the reference, the neutral zone voltage is progressively amplitude-shifted and phase-shifted; point D1 is a characteristic position of the neutral zone near the power supply arm A. Its setting requirements refer to the aforementioned position setting principle of point D, that is, it must meet the requirements of boundary distance with the transition zone, linkage timing with the current detection element, and time adaptation of amplitude-shifting and phase shifting.

[0097] When the train arrives at point C and travels to transition zone A, the railway flexible power supply device is still in the second phase-shifting mode. The railway flexible power supply device completes phase shifting, and the neutral zone voltage... Meanwhile, the output current of the railway flexible power supply device gradually decreases to zero, and the train receives current from arm A, where U a The voltage of arm A of the traction network;

[0098] When the train reaches point B, i.e., when the train leaves transition zone A, the railway flexible power supply device is in standby mode, and the output voltage of the railway flexible power supply device is [not specified]. The RPC and energy storage system then begin operation.

[0099] Example 2

[0100] Based on the same concept, embodiments of the present invention also provide a railway flexible power supply device. In view of the shortcomings of RPC systems and existing phase-splitting devices, embodiments of the present invention address... Figure 3 The structure of the RPC system with hybrid energy storage in the middle section is improved, and a new type of flexible power supply device for railways is proposed. This device not only has functions such as regenerative braking energy transfer, storage, and comprehensive power quality compensation, but also enables trains to flexibly and automatically cross phases. Figure 4 As shown, the device includes a transformer unit, a voltage source converter unit, and a hybrid energy storage unit; wherein the transformer unit and the voltage source converter unit constitute a PRC device.

[0101] Specifically, the transformer unit includes a transformer. ,transformer With transformer ,transformer One end of the primary winding is grounded, and the other end is connected to the A arm of the traction network. (Transformer) One end of the primary winding is grounded, and the other end is connected to the B arm of the traction network. (Transformer) One end of the primary side is grounded, and the other end is connected to the neutral zone.

[0102] The voltage source converter unit includes converters VSCa, VSCb, and VSCn. The AC side of converter VSCa is connected to a transformer. On the secondary side, the AC side of the converter VSCb is connected to the transformer. On the secondary side, the AC side of the converter VSCn is connected to the transformer. The secondary side of the converter. The DC sides of converters VSCa, VSCb, and VSCn are connected together to form a common DC bus, and a DC capacitor is connected across the two ends of this common DC bus. The hybrid energy storage unit is connected in parallel with the common DC bus through a bidirectional DC / DC converter.

[0103] In addition, transformer ,transformer Reactors are connected in series on the secondary side respectively. , Then connect to the AC terminals of converter VSCa and converter VSCb.

[0104] contrast Figure 3 It can be seen that, Figure 4 The new railway flexible power supply device adds a voltage source converter (VSCn) and a matching transformer. The DC side of the converter is connected to the DC link, i.e., in parallel with the DC capacitor; the AC output is connected to the neutral zone.

[0105] In order to enable the train to flexibly cross phases, an additional train position identification system and a traction network and phase-crossing voltage and current measurement system are added.

[0106] The composition of railway flexible power supply devices under different control modes includes:

[0107] When the train has not passed the phase separation zone or has left the phase separation zone, i.e., in standby mode, the converter VSCn is in standby mode, while the converters VSCa, VSCb and other units continue to operate, realizing functions such as power quality management, regenerative braking energy transfer, storage and comprehensive power quality compensation.

[0108] As the train travels in the direction shown in the diagram to the phase-splitting zone, i.e., in the first phase-splitting mode, converters VSCb and VSCn form a flexible phase-splitting device. The traction network A arm continuously supplies power to the train, while the B arm does not directly participate in power supply. Converter VSCb is in rectification or voltage regulation mode, used to stabilize the common DC bus voltage, providing stable DC-side support for VSCn and ensuring controllable amplitude and phase of the VSCn output voltage. Converter VSCn is in inverter mode, using the common DC bus as energy support, outputting AC power with adjustable amplitude, phase, and frequency in the neutral zone, providing voltage support for the neutral section of the phase-splitting zone, enabling the train to pass through the phase-splitting zone without power outages or impacts.

[0109] The train travels in the opposite direction shown in the diagram to the phase-splitting zone, i.e., the second phase-splitting mode. In this mode, converters VSCa and VSCn form a flexible phase-splitting device. The B arm of the traction network continuously supplies power to the train, while the A arm does not directly participate in power supply. Converter VSCa is in rectification or voltage regulation mode, used to stabilize the common DC bus voltage, providing stable DC-side support for VSCn and ensuring controllable amplitude and phase of the VSCn output voltage. Converter VSCn is in inverter mode, using the common DC bus as energy support, outputting AC power with adjustable amplitude, phase, and frequency in the neutral zone, providing voltage support for the neutral section of the phase-splitting zone, enabling the train to pass through the phase-splitting zone without power outages or impacts.

[0110] When the train travels in the direction shown in the diagram to the phase-splitting zone and the power supply arm has insufficient energy (i.e., in supplementary energy mode), the hybrid energy storage unit releases electrical energy and forms a flexible phase-splitting device with converters VSCb and VSCn. Conversely, when the train travels in the opposite direction to the phase-splitting zone and the power supply arm has insufficient energy, the hybrid energy storage unit, converters VSCa and VSCn form a flexible phase-splitting device. The hybrid energy storage unit releases energy to cooperate with the converter unit for power compensation and voltage support.

[0111] When the train travels in the direction shown in the diagram to the phase-splitting zone and the power supply arm is de-energized (i.e., in the no-power supply mode), the hybrid energy storage unit releases electrical energy and forms a flexible phase-splitting device with the converter VSCn. The hybrid energy storage unit independently provides energy, which is then inverted by the converter VSCn to supply power to the phase-splitting zone, ensuring continuous current supply to the train.

[0112] The flexible phase-splitting device achieves a smooth transition of the neutral voltage from one arm to the other by continuously adjusting the voltage amplitude and phase of the neutral segment.

[0113] Railway power regulators can improve power quality and utilize regenerative braking energy in railway traction power supply systems, but they cannot solve the problem of automatic phase crossing for trains. This invention adds a flexible automatic phase crossing function to the existing RPC functionality. When a train crosses a phase crossing zone, there is no need to disconnect power or disconnect the pantograph. By gradually modulating and shifting the neutral voltage, the voltage amplitude and phase of the neutral voltage are gradually aligned with those of the preceding and following power supply arms. This effectively avoids overvoltage, overcurrent, and pantograph-catenary arcing during phase crossing, and allows the train to pass smoothly through the phase crossing zone without load reduction or speed loss. Therefore, the new flexible railway power supply device has more comprehensive functions and a wider range of applications.

[0114] This invention improves the structure of the RPC system with hybrid energy storage and designs a new type of flexible power supply device for railways. The invention also details its architecture and composition, enabling the device to not only perform functions such as regenerative braking energy transfer, storage, and comprehensive power quality compensation, but also to achieve flexible automatic phase transition for trains.

[0115] The paper also presents the composition and workflow of the flexible phase-splitting device under different operating conditions, realizing automatic phase-splitting without power interruption for trains. If flexible power supply devices are used simultaneously in the traction substations and phase-splitting areas of a line, transforming the phase-splitting areas into "continuously energized areas," the length of the power supply section can be significantly extended, the number of traction substations and external power sources can be reduced, transformer capacity can be decreased, investment and operating costs can be significantly reduced, the regenerative utilization rate of train braking energy can be significantly improved, power supply islands along the entire line can be eliminated, and flexible automatic phase-splitting for trains can be achieved, demonstrating broad prospects.

[0116] It should be understood that although the steps in the flowcharts of the embodiments described above are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the embodiments described above may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages of other steps.

[0117] The above embodiments should be understood as being used only to illustrate the present invention more clearly, and not to limit the scope of the present invention. After reading the present invention, any modifications of the present invention in various equivalent forms by those skilled in the art fall within the scope defined by the appended claims.

Claims

1. An automatic phase-crossing method based on a railway flexible power supply device, wherein the railway flexible power supply device includes a transformer unit, a voltage source converter unit, and a hybrid energy storage unit, the transformer unit including three transformers respectively connected to the first arm of the traction network, the neutral region of the phase-crossing zone, and the second arm of the traction network, characterized in that, The method includes the following steps: S1: Detect the train operation status and track section occupancy status at a designated location on the track, generate a status signal, and send the status signal to the flexible over-phase control system; S2: Collect voltage and current signals of the traction network and the phase-splitting zone, and send the collected voltage and current signals to the flexible phase-splitting control system; S3: Preprocess the voltage and current signals to obtain the processed electrical signal; S4: Based on the status signal and the processed electrical signal, switch the control mode of the railway flexible power supply device; S5: The railway flexible power supply device adjusts the voltage amplitude and phase of the phase separation zone according to the corresponding control mode, and smoothly switches the train power supply from the current power supply arm of the traction network to the target power supply arm.

2. The automatic phase-crossing method based on a railway flexible power supply device according to claim 1, characterized in that, The train's operating status includes its position and direction of travel.

3. The automatic phase-crossing method based on a railway flexible power supply device according to claim 1, characterized in that, In S2, the detection of voltage and current in the traction network and phase-separation zone includes: The voltage of the first arm, the second arm, and the phase-separated zone of the traction network is detected by at least one voltage transformer. The current in the first arm, the second arm, and the phase-separated area of ​​the traction network is detected by at least one current transformer; wherein, at least two current transformers are used to detect the current in the phase-separated area.

4. The automatic phase-crossing method based on a railway flexible power supply device according to claim 1, characterized in that, The control modes of the railway flexible power supply device include at least one of the following: standby mode, first phase-crossing mode, second phase-crossing mode, power replenishment mode, and no power supply mode.

5. The automatic phase-crossing method based on a railway flexible power supply device according to claim 4, characterized in that, In S4, the specific components based on the state signal and the processed electrical signal include: When the train has not passed the phase separation zone or has left the phase separation zone, the railway flexible power supply device is switched to standby mode; When the train enters the phase-splitting zone in the first direction and the first and second arms of the traction network have sufficient energy, the railway flexible power supply device is switched to the first phase-splitting mode. When the train enters the phase-splitting zone in the second direction and the first and second arms of the traction network have sufficient energy, the railway flexible power supply device is switched to the second phase-splitting mode.

6. The automatic phase-crossing method based on a railway flexible power supply device according to claim 5, characterized in that, Switching the control mode of the railway flexible power supply device also includes: When the train is in the phase-separation zone and the first and second arms of the traction network are insufficient in energy, the railway flexible power supply device will be switched to the energy replenishment mode. When the train is in the phase separation zone and the first and second arms of the traction network are without power, the railway flexible power supply device is switched to the power-off mode.

7. The automatic phase-crossing method based on a railway flexible power supply device according to claim 5 or 6, characterized in that, The phase separation zone includes a first transition zone, a central zone, and a second transition zone. S5 includes smoothly switching the train power supply from the first arm of the traction network to the second arm, specifically including: When the railway flexible power supply device is in standby mode and the train has not entered the phase-splitting zone, the output voltage of the railway flexible power supply device is... , among which, U a The voltage of the first arm of the traction net; When the railway flexible power supply device is in the first over-phase mode and the train travels to the first transition zone, the railway flexible power supply device begins to output current and increases to I. a The voltage phase remains unchanged, where I a Equal to the actual current of the train; When the railway flexible power supply device is in the first over-phase mode and the train travels to the first preset point in the neutral zone, the railway flexible power supply device uses U b To adjust the reference, the neutral voltage is gradually amplitude-shifted and phase-shifted. When the railway flexible power supply device is in the first phase-over mode and the train travels to the second transition zone, the railway flexible power supply device completes phase shifting, and the neutral zone voltage... Simultaneously, the output current of the railway flexible power supply device gradually decreases to zero, and the train receives current from the second arm, wherein U b The voltage of the second arm of the traction net; When the railway flexible power supply device is in standby mode and the train leaves the phase separation zone, the output voltage of the railway flexible power supply device is... .

8. The automatic phase-crossing method based on a railway flexible power supply device according to claim 5 or 6, characterized in that, The phase separation zone includes a first transition zone, a central zone, and a second transition zone. S5 includes smoothly switching the train power supply from the second arm of the traction network to the first arm, specifically including: When the railway flexible power supply device is in standby mode and the train has not entered the phase-splitting zone, the output voltage of the railway flexible power supply device is... , among which, U b The voltage of the second arm of the traction net; When the railway flexible power supply device is in the second over-phase mode and the train travels to the second transition zone, the railway flexible power supply device begins to output current and increases to I. b The voltage phase remains unchanged, where I b Equal to the actual current of the train; When the railway flexible power supply device is in the second over-phase mode and the train travels to the second preset point in the neutral zone, the railway flexible power supply device uses U a To adjust the reference, the neutral voltage is gradually amplitude-shifted and phase-shifted. When the railway flexible power supply device is in the second phase-shifting mode and the train travels to the first transition zone, the railway flexible power supply device completes phase shifting, and the neutral zone voltage... Simultaneously, the output current of the railway flexible power supply device gradually decreases to zero, and the train receives current from the first arm, wherein U a The voltage of the first arm of the traction net; When the railway flexible power supply device is in standby mode and the train leaves the phase separation zone, the output voltage of the railway flexible power supply device is... .

9. A flexible power supply device for railways, characterized in that, The device includes a transformer unit, a voltage source converter unit, and a hybrid energy storage unit; The transformer unit includes a first transformer, a second transformer, and a third transformer. The primary side of the first transformer is connected to the first arm of the traction network, the primary side of the second transformer is connected to the second arm of the traction network, and the primary side of the third transformer is connected to the neutral zone. The voltage source converter unit includes a first converter, a second converter, and a third converter. The AC side of the first converter is connected to the secondary side of the first transformer, the AC side of the second converter is connected to the secondary side of the second transformer, and the AC side of the third converter is connected to the secondary side of the third transformer. The DC sides of the first converter, the second converter, and the third converter are connected together to form a common DC bus; The hybrid energy storage unit is connected in parallel with the common DC bus via a bidirectional DC / DC converter.

10. The railway flexible power supply device according to claim 9, characterized in that, The composition of the railway flexible power supply device under different control modes includes: In standby mode, the third converter is in standby mode, while the first converter, the second converter, and other units remain in operation. In the first phase-splitting mode, the second converter and the third converter constitute a flexible phase-splitting device; In the second phase-splitting mode, the first converter and the third converter constitute a flexible phase-splitting device; In the energy replenishment mode, the hybrid energy storage unit releases electrical energy and forms a flexible phase-splitting device with the first converter and the third converter or the second converter and the third converter. In the no-power supply mode, the hybrid energy storage unit releases electrical energy and forms a flexible phase-splitting device with the third converter.

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