Electrified Railway Traction Power Supply System and Method Based on Multi-Source Access Structure

Abstract

The present application discloses an electrified railway traction power supply system and method based on a multi-source access structure. The system includes a power supply unit, an energy storage unit, and a traction network unit. The power supply unit includes at least two of a decentralized wind turbine group, a distributed photovoltaic group, a fuel cell group, a diesel engine / small hydropower group, a distribution network, and a high-voltage power grid. The energy storage unit includes an energy storage device, an energy storage converter, and a split-type traction transformer. The electrified railway traction power supply system and method of the present invention get rid of the excessive dependence on the high-voltage power grid, can flexibly form an energy supply system according to the natural endowments such as wind, light, and water at the electrified railway construction site and other convenient power sources, and utilize the energy migration technical characteristics of the energy storage unit of "full-time convergence and on-demand release" to realize the safe, reliable, and continuous power supply of the traction power supply network under a weak grid or even without a grid. At the same time, many adverse problems of the existing electrified railway traction power supply system are solved.

Description

Technical Field

[0001] The present invention relates to an electrified railway traction power supply system and method based on a multi-source access structure, and belongs to the field of railway networks. Background Art

[0002] Electrified railway transportation is an important support for achieving regional economic integration in my country, synergizing cross-regional economic development, and resolving imbalances in socioeconomic development across different regions. However, the existing power grid and traction power supply system are closely coupled, significantly influencing each other, and present numerous problems, as follows:

[0003] (1) Adverse effects of the existing traction power supply system on the grid side

[0004] (1) Under the existing electrified railway traction network and power grid architecture, it is impossible to utilize power from other types of power sources other than the high-voltage power grid.

[0005] (2) The numerous electrical phase separation devices deployed along the traction network require huge investments and high operation and maintenance costs.

[0006] (3) Electric locomotives are high-power, asymmetrical, pulsed single-phase loads, which not only seriously affect the power quality (negative sequence, harmonics, power factor) of the 220kV / 110kV high-voltage power grid, but also increase the peak load regulation pressure of the power grid.

[0007] (2) Adverse effects of the existing traction power supply system on the railway side

[0008] (1) The traction power supply system relies too much on the strong high-voltage power grid, which makes the construction of electrified railways in areas with weak power grids (such as the Sichuan-Tibet and Qinghai-Tibet regions) difficult and costly, seriously affecting the promotion of railway electrification technology in my country.

[0009] (2) The reliability, continuity and safety of the existing electric railway traction system are completely dependent on the power grid system. Once the power grid fails, it will have a significant negative impact on the operation of the electrified railway.

[0010] In view of this, the inventors conducted research on this and specially developed an electrified railway traction power supply system and method based on a multi-source access structure, which led to the present case. Summary of the Invention

[0011] The purpose of the present invention is to provide an electrified railway traction power supply system and method based on a multi-source access structure, which can achieve safe, reliable and continuous power supply for traction networks with weak grids or even without grids.

[0012] In order to achieve the above object, the solution of the present invention is:

[0013] An electrified railway traction power supply system based on a multi-source access structure includes a power supply unit, an energy storage unit, and a traction network unit. The power supply unit charges the energy storage unit, and the energy storage unit supplies power to the traction network unit to meet the power supply requirements of locomotives. Among them, the power supply unit includes at least two of a distributed wind turbine group, a distributed photovoltaic group, a fuel cell group, a diesel engine / small hydropower group, a distribution network, and a high-voltage grid. The energy storage unit includes an energy storage device, a number of energy storage converters connected to the energy storage device, and a split-type traction transformer for boosting voltage.

[0014] Preferably, the distributed wind turbine group, the distributed photovoltaic group, and the fuel cell group form a DC microgrid structure or an AC microgrid to charge the energy storage device cooperatively.

[0015] Preferably, the diesel engine / small hydropower group directly provides electrical energy to the energy storage device through a low-voltage AC bus (determined by the outlet voltage level).

[0016] Preferably, the distribution network is a 10 / 35 kV distribution network, and the high-voltage grid is a 66 / 110 / 220 kV high-voltage grid. The 10 / 35 kV distribution network is connected to a low-voltage AC bus (0.4 kV) through a step-down transformer (facilitating the selection of equipment such as transformers and switches) to charge the energy storage device. The 66 / 110 / 220 kV high-voltage grid is connected to a high-voltage AC bus (27.5 kV) through a traction step-down transformer and a switch (the switch is disconnected when there is a locomotive in the power supply arm and closed when there is no locomotive in the power supply arm) (facilitating the selection of equipment such as transformers and switches) to provide electrical energy to the energy storage device.

[0017] Preferably, the fuel cell group is connected to a hydrogen production device to generate electrical energy through the hydrogen production device.

[0018] Preferably, the energy storage device adopts one or several of an electrochemical energy storage device, a physical energy storage device, and an electromagnetic energy storage device.

[0019] Preferably, the electrochemical energy storage device adopts one or several of a lead-acid battery, a lead-carbon battery, a sodium-sulfur battery, a full-flow battery, a lithium battery, or a fuel cell.

[0020] Preferably, the physical energy storage device adopts one or several of pumped storage, flywheel energy storage, or compressed air.

[0021] Preferably, the electromagnetic energy storage device adopts one or several of a supercapacitor or a superconducting magnet.

[0022] A power supply method for an electrified railway traction power supply system based on a multi-source access structure includes the following steps:

[0023] (1) When the two-power-supply-arm locomotive is pulling, the power supply unit charges the energy storage unit with a small current balance, and the energy storage unit generates electricity to meet the power demand of the locomotive. The specific quantitative relationship is:

[0024]

[0025] Where: P load is the total power demand of the two locomotives; P α 、P β are the locomotive power requirements on the two power supply arms; P deα 、P deβ are the powers provided by the energy storage unit to the two power supply arms; P s P is the charging power from the power supply unit to the energy storage unit; E放 、P E充 are the actual power consumption and charging power of the energy storage unit respectively.

[0026] (2) When one power supply arm is traction and the other power supply arm is braking, the power supply unit charges the energy storage unit with a small current balance. The energy storage unit meets the power demand of the traction locomotive and recovers the feedback energy of the braking locomotive at the same time. The specific quantitative relationship is:

[0027]

[0028] Where: P ceβ Feeds back energy to the braking locomotive.

[0029] (3) When one power supply arm is traction and the other power supply arm is unloaded, the power supply unit charges the energy storage unit with a small current balance, and the energy storage unit meets the power demand of the traction locomotive. The specific quantitative relationship is:

[0030]

[0031] (4) When the two power supply arms of the locomotive brake, the power supply unit charges the energy storage unit with a small current balance, and the energy storage unit recovers the braking energy of the locomotive. The specific quantitative relationship is:

[0032] P E充 =P s +P ceα +P ceβ (4)

[0033] Where: P ceα Feedback energy to a power arm brake locomotive.

[0034] (5) When one power supply arm is braking and the other power supply arm is unloaded, the power supply unit charges the energy storage unit with a small current balance, and the energy storage unit recovers the braking energy of the locomotive. The specific quantitative relationship is:

[0035] P E充 =P s+P ceα (5)

[0036] (6) When the two power supply arms are no-load, the power supply unit charges the energy storage unit with a small current for equalization. The specific quantitative relationship is

[0037] P E充 =P s (6)

[0038] The electrified railway traction power supply system and method based on a multi-source access structure described in the present invention get rid of the excessive dependence on the high-voltage power grid, can flexibly form an energy supply system according to the natural endowments such as wind, light, and water and other convenient power sources in the construction area of the electrified railway, and utilize the energy migration technical characteristics of the energy storage unit of "full-time convergence and on-demand release" to realize the safe, reliable, and continuous power supply of the traction power supply network under weak or even no grid frameworks, while solving many adverse problems of the existing electrified railway traction power supply system.

[0039] The following further describes the present invention in detail with reference to the accompanying drawings and specific embodiments. Description of the Drawings

[0040] Figure 1 Topological structure diagram of the electrified railway traction power supply system based on a multi-source access structure for Embodiment 1 (common DC microgrid);

[0041] Figure 2 Topological structure diagram of the electrified railway traction power supply system based on a multi-source access structure for Embodiment 2 (common AC microgrid);

[0042] Figure 3 Schematic diagram of energy flow for Embodiment 3 (operating condition 1);

[0043] Figure 4 Schematic diagram of energy flow for Embodiment 3 (operating condition 2);

[0044] Figure 5 Schematic diagram of energy flow for Embodiment 3 (operating condition 3);

[0045] Figure 6 Schematic diagram of energy flow for Embodiment 3 (operating condition 4);

[0046] Figure 7 Schematic diagram of energy flow for Embodiment 3 (operating condition 5);

[0047] Figure 8 Schematic diagram of energy flow for Embodiment 3 (operating condition 6);

[0048] Figure 9 Schematic diagram of the energy quantitative relationship under 6 operating conditions in Embodiment 3. Detailed Embodiment

[0049] Embodiment 1

[0050] As Figure 1 shown, an electrified railway traction power supply system based on a multi-source access structure includes a power supply unit 1, an energy storage unit 2, and a traction network unit 3. The power supply unit 1 is a multi-type power supply unit, and various types of power supplies can be configured according to local specific resource conditions and grid structures as needed, and flexibly combined. It may include A distributed wind turbines 11, B distributed photovoltaic sets 12, C fuel cell sets 13, D diesel engine / small hydropower sets 14, a 10 / 35 kV distribution network 15, and a 66 / 110 / 220 kV high-voltage grid 16.

[0051] The energy storage unit 2 includes N sets of energy storage devices 21, N*m energy storage converters 22 connected to the energy storage devices 21, and N split-type traction transformers 23 for boosting voltage. The energy storage devices 21 can adopt one or several of electrochemical energy storage devices, physical energy storage devices, and electromagnetic energy storage devices. The electrochemical energy storage devices adopt one or several of lead-acid batteries, lead-carbon batteries, sodium-sulfur batteries, all-flow batteries, lithium batteries, or fuel cells. The physical energy storage devices adopt one or several of pumped storage, flywheel energy storage, or compressed air. The electromagnetic energy storage devices adopt one or several of supercapacitors or superconducting electromagnets. Specifically, it can be determined according to the actual engineering geographical location, local resources, technical maturity and characteristics, economy, etc., and the energy storage capacity and technical solution are configured in a customized manner. The energy storage unit 2 converges the energy of various types of heterogeneous power supplies in real time to meet the electrical energy required when the power vehicle passes through. The energy storage converter 22 realizes the bidirectional conversion between the direct current and alternating current of the energy storage.

[0052] In this embodiment, the distributed wind turbines 11, distributed photovoltaic units 12, and fuel cell units 13 form a DC microgrid structure to jointly charge the energy storage device 21. The fuel cell unit 13 is connected to the hydrogen production device 17 to generate electric energy through the hydrogen production device 17. The diesel engine / small hydropower unit 14 directly supplies electric energy to the energy storage device 21 through a 0.4 kV low-voltage AC bus (determined by the outlet voltage level). The 10 / 35 kV distribution network is connected to the 0.4 kV low-voltage AC bus through a step-down transformer 4 (facilitating the selection of equipment such as transformers and switches) to charge the energy storage device; the 66 / 110 / 220 kV high-voltage grid is connected to the 27.5 kV high-voltage AC bus through a traction step-down transformer 5 and a switch 6 (when there is a locomotive passing through the power supply arm, the switch 6 is disconnected, and when there is no locomotive in the power supply arm, the switch 6 is closed) (facilitating the selection of equipment such as transformers and switches) to supply electric energy to the energy storage device 21. The 0.4 kV low-voltage AC bus realizes the interconnection between each section through a sectional switch 24. Adding the sectional switch 24 can facilitate the selection of the low-voltage bus capacity. m energy storage converters 22 are connected to one split-type traction transformer 23 to realize the transfer of energy storage energy. N split-type traction transformers 23 boost the 0.4 kV AC low voltage to form a 27.5 kV traction network to meet the power supply requirements of locomotives.

[0053] The traction network unit 3 mainly consists of a catenary, track, return line, locomotive, substation, etc.

[0054] The above-mentioned electrified railway traction power supply system based on a multi-source access structure can be divided into three operating conditions according to the operating state:

[0055] (1) Energy storage discharge mode (on demand): When the main control monitors that there is a locomotive passing through the power supply arm and is in the traction state, at this time, multiple energy storages cooperate to output power (if there is a distribution network or high-voltage grid in the power supply unit 1, the connected switch is disconnected at this time to avoid affecting the power quality of the grid, and devices such as wind power, photovoltaic, or fuel cells can continue to charge the energy storage). To meet the power consumption requirements of electric locomotives.

[0056] (2) Energy storage charging mode (full time): When the main control system monitors that there is no locomotive passing through the power supply arm or it is operating in the coasting state, various types of heterogeneous power sources in the power supply unit 1 charge the energy storage device 21 with a small current for balancing; when the main control system monitors that the locomotive in the power supply arm is operating in the braking state, various types of heterogeneous power sources (such as if the power supply unit includes a distribution network or high-voltage grid, the connecting switch is disconnected and in the hot standby state, and does not charge the energy storage unit) charge the energy storage device 21 with a small current for balancing, and at the same time, the energy storage unit 2 recovers the braking energy of the electric locomotive.

[0057] (3) Energy storage auxiliary service mode (according to the plan): When the components of the power supply unit 1 include a distribution network or a high-voltage grid, and the grid requires auxiliary services such as peak shaving, frequency modulation, and voltage regulation, on the premise of meeting the locomotive power supply demand, the energy storage unit 2 interacts intelligently with the grid according to the planned output curve issued by the grid to provide auxiliary services for the grid.

[0058] Embodiment 2

[0059] In this embodiment, as Figure 2 shown, the decentralized wind turbine units 11, distributed photovoltaic units 12, and fuel cell units 13 form an AC microgrid structure to jointly charge the energy storage device 21. The decentralized wind turbine units 11, distributed photovoltaic units 12, and fuel cell units 13 converge on a 0.7 kV AC bus (the voltage level is determined by the AC outlet voltage of the wind turbine unit). The electrical connection conditions and equipment principles of other parts are the same as those in Embodiment 1, so they will not be elaborated here.

[0060] Embodiment 3

[0061] A power supply method for an electrified railway traction power supply system based on a multi-source access structure includes the following steps:

[0062] (1) Condition 1: As Figure 3 shown, when the locomotives on two power supply arms are in traction, the power supply unit 1 charges the energy storage unit 2 with a small current for equalization. The energy storage unit 2 generates electric energy to meet the locomotive power consumption demand. The specific quantitative relationship is

[0063]

[0064] In the formula: P load is the total power demand of the two locomotives; P α , P β are the power demands of the locomotives on the two power supply arms respectively; P deα , P deβ are the powers provided by the energy storage unit 2 to the two power supply arms respectively; P s is the charging power of the power supply unit 1 to the energy storage unit; P E放 , P E充 are the actual power consumption and charging power of the energy storage unit 2 respectively.

[0065] (2) Condition 2: As Figure 4 shown, when the locomotive on one power supply arm is in traction and the locomotive on the other power supply arm is in braking, the power supply unit 1 charges the energy storage unit 2 with a small current for equalization. The energy storage unit 2 meets the power consumption demand of the traction locomotive and simultaneously recovers the feedback energy of the braking locomotive. The specific quantitative relationship is

[0066]

[0067] In the formula: P ceβTo brake the locomotive and feedback energy.

[0068] (3) Condition 3: As Figure 5 shown, when a locomotive on one power supply arm is in traction and the locomotive on the other power supply arm is unloaded, the power supply unit 1 charges the energy storage unit 2 with a small current for equalization. The energy storage unit 2 meets the power consumption requirements of the traction locomotive. The specific quantitative relationship is

[0069]

[0070] (4) Condition 4: As Figure 6 shown, when locomotives on both power supply arms are braking, the power supply unit 1 charges the energy storage unit 2 with a small current for equalization. The energy storage unit 2 recovers the braking energy of the locomotive. The specific quantitative relationship is

[0071] P E充 =P s +P ceα +P ceβ (4)

[0072] In the formula: P ceα is the energy feedback from braking the locomotive on one power supply arm.

[0073] (5) Condition 5: As Figure 7 shown, when a locomotive on one power supply arm is braking and the locomotive on the other power supply arm is unloaded, the power supply unit 1 charges the energy storage unit 2 with a small current for equalization. The energy storage unit 2 recovers the braking energy of the locomotive. The specific quantitative relationship is

[0074] P E充 =P s +P ceα (5)

[0075] (6) Condition 6: As Figure 8 shown, when both power supply arms are unloaded, the power supply unit 1 charges the energy storage unit 2 with a small current for equalization. The specific quantitative relationship is

[0076] P E充 =P s (6)

[0077] Figure 9 is the schematic diagram of the energy quantitative relationship under the above 6 conditions.

[0078] The electrified railway traction power supply system and method based on the multi-source access structure described in this application have the following advantages:

[0079] I. Benefits to the railway side

[0080] (1) This new type of electrified railway traction power supply system based on energy storage and multi-source access structure subverts the traditional power supply mode of the electrified railway traction system. According to the natural endowments of wind, light, water, etc. and the power grid architecture in different regions, using the energy time migration technical characteristics of energy storage to "fully converge and release on demand" for various types of heterogeneous power sources, the power supply scheme of the traction power supply system is designed in a customized manner to achieve the economic construction of the electrified railway traction power supply system in areas with weak or even no power grid.

[0081] (2) It changes the existing traction substation, reduces or even cancels large-capacity traction transformers, while significantly improving the utilization rate of transformers and greatly reducing the capacity electricity fees paid annually.

[0082] (3) Through the energy storage unit 2, the reactive power regulation ability of the PCS converter can be utilized to reduce the capacity of reactive power regulation equipment such as SVC / SVG, and reduce the initial investment and later operation and maintenance costs of the equipment.

[0083] (4) The energy storage unit 2 can completely recover the braking energy of locomotives and multiple units, avoid the waste of high-quality electric energy, weaken the pressure on the locomotive heat dissipation equipment, and at the same time, the locomotive does not need to be equipped with a large number of unloading resistors, reducing the vehicle load and facilitating the lightweight design of locomotives and multiple units.

[0084] (5) The electrical equipment in the traction power supply system adopts a modular design, and the electrical equipment is reasonably and dispersedly arranged according to the on-site location, greatly reducing the on-site equipment installation and construction volume of the civil engineering, shortening the project construction period, reducing the construction cost, reducing the land area occupation, and having little ecological impact.

[0085] (6) The selection of power source types and energy storage types is extensive and the combination is free. It can be completely independent of the power grid and locally utilize natural endowments such as wind, light, and water to achieve the self-consistency of the energy supply of the electrified railway system. The electrical network framework configuration is intensive and streamlined, improving the flexibility of the electrified railway construction.

[0086] (7) The traction power supply system is arranged in a decentralized manner, the equipment is unitized, and the control is centralized. The power supply unit and the energy storage unit have a relatively high configuration redundancy, and the continuity, reliability, and safety of the traction power supply are relatively high.

[0087] (8) It can achieve clean propulsion of high-speed railways, promote the integrated development of new energy / renewable energy and railways, improve the continuous stability of the traction power supply system and its adaptability to energy supply conditions and the environment, improve the electrified railway technology system in China, lead the green development of electrified railways, and provide a feasible solution for the construction and operation of electrified railways in areas with weak or even no power grid.

[0088] II. Benefits to the grid side

[0089] (1) Energy storage is used to block the direct connection between the traction network and the power grid, achieving loose coupling between the power grid and the traction network, and eliminating the negative sequence, harmonics, power factor and other power quality effects brought to the high-voltage power grid by the existing traction power supply system.

[0090] (2) It can eliminate the impact of the traction power supply system on the power quality of the high-voltage power grid, thereby eliminating a large number of electrical phase separation equipment, greatly reducing engineering construction investment and subsequent operation and maintenance costs.

[0091] (3) There is no need to build 220kV high-voltage transmission lines and high-voltage traction substations, which reduces the related primary and secondary electrical equipment, reduces the land acquisition area, greatly reduces the project cost, shortens the project period, and reduces the subsequent operation and maintenance costs.

[0092] (4) It has the functions of both a traction substation and an energy storage power station, realizing the integration of the two functions. It can not only meet the electricity demand of locomotives, but also provide auxiliary services such as peak regulation, frequency regulation, and voltage regulation for the power grid, thereby improving the regulation margin of the power grid and promoting the construction of a high proportion of clean energy in the power grid.

[0093] (5) The power supply unit in the power supply unit has a relatively small capacity. Multiple types of heterogeneous power supplies work together in real time to provide small current balanced charging for the energy storage unit (which is beneficial to extend the life of the energy storage system and improve the utilization rate of the transformer). The energy storage unit gathers the electric energy of various power supplies and releases it in a concentrated manner when the locomotive is running in the traction state to meet the power supply needs of high-power and impact locomotive loads. With a small power supply, a large amount of power is achieved, and a small power supply is used to provide safe, reliable and continuous power supply for high-power and intermittent loads.

[0094] (6) The energy storage unit 2 can be used as an emergency power supply for the electric railway traction power supply system, and can also be used as a black start power supply for the power grid.

[0095] (7) The power supply is green, clean and environmentally friendly, and the proportion of clean energy power generation has been increased.

[0096] As described above, the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A power supply method for an electrified railway traction power supply system based on a multi-source access structure, characterized in that: The electrified railway traction power supply system includes a power supply unit, an energy storage unit, and a traction network unit. The power supply unit charges the energy storage unit, and the energy storage unit supplies power to the traction network unit to meet the power supply needs of the locomotive. The power supply unit includes at least two of a distributed wind turbine group, a distributed photovoltaic group, a fuel cell group, a diesel engine / small hydropower group, a distribution network, and a high-voltage power grid. The energy storage unit includes an energy storage device, a plurality of energy storage converters connected to the energy storage device, and a split traction transformer for boosting. The power supply method includes the following steps: (1) When the two-power-supply-arm locomotive is pulling, the power supply unit charges the energy storage unit with a small current balance, and the energy storage unit generates electricity to meet the power demand of the locomotive. The specific quantitative relationship is: Where: P load is the total required power of the two locomotives; P α and P β are the power demands of the locomotives on the two power supply arms respectively; P deα and P deβ are the powers provided by the energy storage unit to the two power supply arms respectively; P s is the charging power of the power supply unit to the energy storage unit; P E放 and P E充 are the actual power consumption and charging power of the energy storage unit respectively; (2) When one power supply arm is traction and the other power supply arm is braking, the power supply unit charges the energy storage unit with a small current balance. The energy storage unit meets the power demand of the traction locomotive and recovers the feedback energy of the braking locomotive at the same time. The specific quantitative relationship is: Where: P ceβ is the energy fed back by the braking locomotive; (3) When one power supply arm is traction and the other power supply arm is unloaded, the power supply unit charges the energy storage unit with a small current balance, and the energy storage unit meets the power demand of the traction locomotive. The specific quantitative relationship is: (4) When the two power supply arms of the locomotive brake, the power supply unit charges the energy storage unit with a small current balance, and the energy storage unit recovers the braking energy of the locomotive. The specific quantitative relationship is: P E充 = P s + P ceα + P ceβ (4) Where: P ceα is the feedback energy of the locomotive with a braking unit on a power supply arm; (5) When one power supply arm is braking and the other power supply arm is unloaded, the power supply unit charges the energy storage unit with a small current balance, and the energy storage unit recovers the braking energy of the locomotive. The specific quantitative relationship is: P E充 = P s + P ceα (5) (6) When the two power supply arms are unloaded, the power supply unit charges the energy storage unit with a small current balance. The specific quantitative relationship is: P E充 = P s (6).

2. The power supply method of the electrified railway traction power supply system based on the multi-source access structure according to claim 1, characterized in that: The distributed wind turbine group, distributed photovoltaic group, and fuel cell group form a DC microgrid structure or an AC microgrid to collaboratively charge the energy storage device.

3. The power supply method of the electrified railway traction power supply system based on the multi-source access structure according to claim 1, characterized in that: The diesel engine / small hydropower group directly provides electric energy to the energy storage device through the low-voltage AC bus.

4. The power supply method of the electrified railway traction power supply system based on the multi-source access structure according to claim 1, characterized in that: The distribution network is a 10 / 35kV distribution network, and the high-voltage power grid is a 66 / 110 / 220kV high-voltage power grid. The 10 / 35kV distribution network is connected to the low-voltage AC bus through a step-down transformer to charge the energy storage device; the 66 / 110 / 220kV high-voltage power grid is connected to the high-voltage AC bus through a traction step-down transformer and a switch to provide power to the energy storage device.

5. The power supply method of the electrified railway traction power supply system based on the multi-source access structure according to claim 1, characterized in that: The fuel cell group is connected to the hydrogen production equipment to generate electrical energy.

6. The power supply method of the electrified railway traction power supply system based on the multi-source access structure according to claim 1, characterized in that: The energy storage device adopts one or more of electrochemical energy storage devices, physical energy storage devices, and electromagnetic energy storage devices.

7. The power supply method of the electrified railway traction power supply system based on the multi-source access structure according to claim 6, characterized in that: The electrochemical energy storage device adopts one or more of lead-acid batteries, lead-carbon batteries, sodium-sulfur batteries, full-flow batteries, lithium batteries or fuel cells.

8. The power supply method of the electrified railway traction power supply system based on the multi-source access structure according to claim 6, characterized in that: The physical energy storage device adopts one or more of pumped storage, flywheel storage or compressed air.

9. The power supply method of the electrified railway traction power supply system based on the multi-source access structure according to claim 6, characterized in that: The electromagnetic energy storage device adopts one or more of supercapacitors or superconducting electromagnetics.

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