Three-phase-to-single-phase traction power supply system for electrified railway
By using the active compensation device of the parallel converter power unit in the electrified railway three-phase to single-phase traction power supply system and directly connecting it between the traction transformer and the railway traction network, the existing system solves the problem of large space, high cost and high cost in the existing system. To solve the problem of large losses, high-voltage direct-mounted large-capacity output is realized, which reduces system losses and construction difficulty.
Patent Information
- Application Number
- CN202420713526.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Priority Date
- 2023-11-27
- Filing Date
- 2024-04-08
- Publication Date
- 2025-01-21
- Estimated Expiration
- 2034-04-08
AI Technical Summary
The existing AC traction power supply system has problems with power quality and excessive equality, and the active compensation device needs to be connected to the traction transformer through an additional transformer, resulting in large footprint, high cost, large losses, and high design and construction difficulties.
An electrified railway three-phase to single-phase traction power supply system is adopted, in which the active compensation device consists of several parallel converter power units, which are directly connected between the traction transformer and the railway traction network to achieve high-voltage direct-connection and large-capacity output. No additional matching transformer is required.
It reduces the area and cost of the transformer, reduces the system loss, simplifies the construction difficulty, and improves the integration and application promotion benefits.
Smart Images
Figure CN222381341U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of traction power supply, and more specifically, to a three-phase to single-phase traction power supply system for an electrified railway. Background Art
[0002] The AC traction power supply system is a system that supplies power to the traction load of the electric locomotive in the traction network after the high voltage voltage of the three-phase power grid is stepped down by the traction transformer. Since the traction load is a single-phase strongly nonlinear load, it is easy to cause an imbalance in the three-phase system of the power grid, causing negative sequence power, increasing network losses, and reducing the transmission capacity of the power grid.
[0003] In order to make the three phases of the power system as balanced as possible, the traction substation implements the phase-changing power supply mode for the overhead line. In order to prevent short circuit between phases, the phases of the overhead line are separated by insulating materials, which is called electrical phase separation. Figure 1 As shown in the figure, after the 110kV voltage of the three-phase power grid is stepped down by the voltage changing point, an electrical phase separation area will be set up every few dozen kilometers in the contact network. The existence of electrical phase separation will cause the loss of train speed and traction, causing transient overvoltage shock of the bow network. In severe cases, it may cause the risk of live phase separation, which will have an adverse impact on the safe operation of electrified railways. At the same time, the fluctuation of traction load causes the voltage fluctuation of the traction network. When the load changes drastically and exceeds the voltage range specified by the locomotive, it will affect the normal operation of the locomotive. In addition, the traditional DC locomotive uses AC / DC converter, which leads to low power factor, affects the power quality, and reduces the power supply capacity of the traction network.
[0004] In order to solve the problems of power quality and over-phase in the existing AC traction power supply system, many solutions have been proposed. Among them, installing a three-phase to single-phase power supply device in the traction substation is one of the effective measures to solve the problems of negative sequence, reactive power, voltage fluctuation, over-phase and so on. Figure 2 As shown in the figure, the current common three-phase to single-phase power supply system adopts active compensation device. After the 110kV voltage of the three-phase power grid is stepped down by the transformer, the low-voltage winding side is connected to the active compensation device to realize the same-phase power supply of the electric locomotive. There are two main topological structures of active compensation device. One is the "AC-DC-AC" main circuit topology scheme with cascade on one side and multiple parallel on the other side. Among them, the cascade side is connected to the low-voltage winding of the traction transformer through a single-phase transformer, and the parallel side is connected to the traction network through a single-phase multi-winding transformer. The other is the "AC-DC-AC" main circuit topology scheme of active compensation device with single-phase multi-winding transformers in parallel transformation at both ends; the above two "AC-DC-AC" main circuit topology schemes of active compensation device need to match the boost and step-down of traditional transformers for power conversion. The additional introduction of transformers not only occupies a large area and has low integration, but also increases the cost and loss of active compensation device. At the same time, the electromagnetic coupling between the windings of the single-phase multi-winding transformer will increase the difficulty of transformer design and construction, and the transformer short-circuit impedance is high, which is not conducive to promotion. Utility Model Content
[0005] In order to solve the problem that the active compensation device of the current active compensation type three-phase to single-phase power supply system needs to be connected to the traction transformer through an additional transformer, resulting in a large transformer footprint in the three-phase to single-phase power supply system and increasing the cost and loss of the active compensation device, the present invention proposes an electrified railway three-phase to single-phase traction power supply system. The main circuit of the active compensation device does not need to be connected to the traction network by a transformer, which reduces the footprint of the transformer and has high integration. The reduced footprint also reduces the difficulty of construction, which is conducive to application and promotion.
[0006] The utility model aims to solve the above technical problems at least to a certain extent.
[0007] In order to solve the above technical problems, the technical solutions adopted by the utility model are as follows:
[0008] An electrified railway three-phase to single-phase traction power supply system, comprising a traction transformer and an active compensation device; the traction transformer comprises a primary winding, a first secondary winding and a second secondary winding, the primary winding is connected to a three-phase power grid, one end of the first secondary winding is directly connected to a railway traction network, and the other end is grounded;
[0009] The active compensation device is composed of a plurality of parallel-connected current conversion power units, and the plurality of parallel-connected current conversion power units are provided with at least four connection interfaces, including a first interface, a second interface, a third interface and a fourth interface. One end of the second secondary winding is connected to the first interface, and the other end is connected to the second interface. The third interface is connected to a railway traction network, and the fourth interface is grounded.
[0010] Through the above-mentioned technical means, the active compensation device is composed of several parallel-connected converter power units, which are directly connected between the traction transformer and the railway traction network to achieve high-voltage direct-hanging large-capacity output. It does not require an additional matching transformer, has a small footprint, high integration, and reduces losses and system costs, which is conducive to application and promotion.
[0011] Preferably, the other end of the second secondary winding is connected to the second interface via a high-voltage switch, and the third interface is connected to the railway traction network via a high-voltage switch.
[0012] According to the above technical means, the high-voltage switch can switch and control the access of the active compensation device.
[0013] Preferably, each of the power conversion units includes: a voltage-controlled rectifier module, a high-frequency power control module and a current-controlled inverter module. The high-frequency power control module includes a DC-AC rectifier, a high-frequency transformer and an AC-DC inverter. The input end of the voltage-controlled rectifier module is connected to the single-phase industrial frequency AC voltage, the output end of the voltage-controlled rectifier module is connected to the input end of the DC-AC rectifier, the output end of the DC-AC rectifier is connected to the primary winding of the high-frequency transformer, the secondary winding of the high-frequency transformer is connected to the input end of the AC-DC inverter, and the output end of the AC-DC inverter is connected to the input end of the current-controlled inverter module.
[0014] According to the above technical means, the voltage-controlled rectifier module rectifies the single-phase industrial frequency AC voltage to achieve DC voltage regulation. The DC voltage is modulated into a high-frequency square wave by the DC-AC rectifier on the primary winding side of the high-frequency transformer. After being coupled to the secondary winding, it is restored to a DC voltage by the DC-AC rectifier. Finally, it is inverted by the current-controlled inverter module to obtain the required single-phase industrial frequency 27.5kV AC voltage. The high-frequency transformer plays an isolation and voltage matching role, avoiding the introduction of additional traditional transformers in the main circuit, reducing costs, and achieving high-voltage direct-hanging and large-capacity output.
[0015] Preferably, the DC-AC rectifier is a two-level, three-level or five-level rectifier.
[0016] Preferably, the AC-DC inverter is a two-level, three-level or five-level inverter.
[0017] Preferably, a DC interface is provided at the output end of each voltage-controlled rectifier module and / or the output end of each AC-DC inverter, and the active compensation device is connected to the distributed power source via the DC interface.
[0018] Preferably, a DC interface is provided at the output end of each voltage-controlled rectifier module and / or the output end of each AC-DC inverter, and the active compensation device is connected to the distributed energy storage via the DC interface.
[0019] According to the above technical means, a DC interface is set on the active compensation device to support the access of distributed energy storage and distributed power sources. The active compensation device can be based on the load of the traction substation; with the help of distributed power sources, the power supply is coordinated to overcome the power quality problem. With the help of distributed energy storage, the braking energy generated during the regenerative braking of the train can be recovered and stored in the distributed energy storage. When the train is towed, the stored energy is released to the traction network for the train to use, so that the regenerated energy can be directly used within the traction power supply system, and various distributed energy storage and new energy generation can be flexibly and reliably integrated into the traction power supply system, thereby improving the utilization rate of line regenerative energy. At the same time, it can cut peaks and fill valleys and reduce the maximum load of the substation.
[0020] Preferably, the distributed power source includes photovoltaics and wind turbines.
[0021] Preferably, the distributed energy storage includes batteries, supercapacitors and flywheel energy storage.
[0022] Preferably, the traction transformer is a SCOTT transformer or a Vv transformer.
[0023] Compared with the prior art, the technical solution adopted by the utility model has the following beneficial effects:
[0024] The utility model proposes an electrified railway three-phase to single-phase traction power supply system, including a traction transformer and an active compensation device. The active compensation device is composed of a plurality of parallel-connected current conversion power units and is directly hung between the traction transformer and the railway traction network to achieve high-voltage direct hanging and large-capacity output. No additional matching transformer is required, the footprint is small, the integration is high, and the loss and system cost are reduced, which is conducive to application and promotion. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] Figure 1 A schematic diagram showing the circuit structure of a conventional traction power supply method using electrical phase separation proposed in the background technology of the utility model;
[0026] Figure 2 A schematic diagram showing the circuit structure of a three-phase to single-phase power supply system currently using an active compensation device and introducing a transformer in the background technology of the present utility model;
[0027] Figure 3 A topological structure diagram showing a three-phase to single-phase traction power supply system for an electrified railway proposed in an embodiment of the utility model;
[0028] Figure 4 A topological structure diagram showing each of the current conversion power units of the active compensation device in the three-phase to single-phase traction power supply system for electrified railways proposed in an embodiment of the utility model;
[0029] Figure 5 A schematic diagram showing a DC interface provided on an active compensation device proposed in an embodiment of the utility model. In which, 1-traction transformer; 2-active compensation device; 21-voltage control rectifier module; 22-high frequency power control module; 23-current control inverter module; 3-DC interface; 101-M seat; 102-T seat; 221-high frequency transformer. DETAILED DESCRIPTION
[0030] The drawings are for illustrative purposes only and should not be construed as limiting the present patent;
[0031] In order to better illustrate the present embodiment, some parts in the drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product;
[0032] It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings;
[0033] The terms used in the drawings to describe positional relationships are only used for illustrative purposes and should not be construed as limiting this patent;
[0034] The technical solution of the utility model is further described below in conjunction with the accompanying drawings and embodiments.
[0035] Example 1
[0036] like Figure 3 As shown, this embodiment proposes an electrified railway three-phase to single-phase traction power supply system, including a traction transformer 1 and an active compensation device 2; see Figure 3 The traction transformer 1 includes a primary winding, a first secondary winding and a second secondary winding, wherein the primary winding is connected to a three-phase power grid, such as Figure 3 As shown, the primary winding is respectively connected to the A phase, B phase, and C phase of the three-phase power grid. The three-phase power grid represents a 110kV input on the high-voltage side. In this embodiment, one end of the first secondary winding is directly connected to the railway traction network, and the other end is grounded. At this time, the first secondary winding can be represented by an M seat 101, and a direct supply loop is formed between the railway traction network. The first secondary winding M seat 101 is directly connected to the railway traction network, and the railway traction network voltage is 27.5kV AC voltage; at this time, the second secondary winding can be represented by a T seat 102, as shown in FIG. Figure 3 As shown, the active compensation device 2 is composed of a number of parallel-connected current conversion power units, and the parallel-connected current conversion power units are provided with four connection interfaces, including a first interface a, a second interface b, a third interface c and a fourth interface d. One end of the second secondary winding is connected to the first interface a, and the other end is connected to the second interface b. The third interface c is connected to the railway traction network, and the fourth interface d is grounded. It can be seen that the second secondary winding T seat 102 of the traction transformer 1 is directly connected to the 27.5kV railway traction network through the active compensation device 2, realizing high-voltage direct hanging and large-capacity output, without the need for an additional matching transformer, with a small footprint and high integration, which can effectively reduce the construction difficulty, and can greatly reduce the loss and system cost, which is conducive to application and promotion.
[0037] In this embodiment, see Figure 3 The other end of the second secondary winding T seat 102 is connected to the second interface b through a high-voltage switch, and the third interface c is connected to the railway traction network through a high-voltage switch. The high-voltage switch is not limited to the selection of isolating switches and circuit breakers. The use of a high-voltage switch can switch and control the access of the active compensation device.
[0038] In this embodiment, the second secondary winding T seat 102 of the traction transformer 1 is directly connected to the 27.5kV railway traction network through the active compensation device 2. After the active compensation device 2 is directly connected, the traction load of the 27.5kV direct supply circuit of the first secondary winding M seat 101 and the negative sequence of the 110kV three-phase power grid can be synchronously monitored. According to the balanced compensation strategy, the power is transmitted, and the current imbalance on the 110kV three-phase power grid side can be further managed. In addition, after the active compensation device 2 is directly connected, the reactive power of the 27.5kV direct supply circuit of the first secondary winding M seat 101 can be synchronously monitored, and the reactive power of the 27.5kV direct supply circuit can be automatically compensated according to the reactive power compensation strategy.
[0039] In this embodiment, the traction transformer 1 is a SCOTT transformer. In other specific implementations, the traction transformer 1 is not limited to being a SCOTT transformer, but may also be replaced by a Vv transformer.
[0040] Example 2
[0041] like Figure 4 As shown, each of the power conversion units includes: a voltage-controlled rectifier module 21, a high-frequency power control module 22 and a current-controlled inverter module 23. The high-frequency power control module 22 includes a DC-AC rectifier, a high-frequency transformer 221 and an AC-DC inverter. The input end of the voltage-controlled rectifier module 23 is connected to a single-phase industrial frequency AC voltage, the output end of the voltage-controlled rectifier module 21 is connected to the input end of the DC-AC rectifier, the output end of the DC-AC rectifier is connected to the primary winding of the high-frequency transformer 221, the secondary winding of the high-frequency transformer 221 is connected to the input end of the AC-DC inverter, and the output end of the AC-DC inverter is connected to the input end of the current-controlled inverter module 23.
[0042] In this embodiment, the voltage-controlled rectifier module 21 rectifies the single-phase industrial frequency AC voltage to achieve DC voltage regulation. The DC voltage is modulated into a high-frequency square wave by the DC-AC rectifier on the primary winding side of the high-frequency transformer 221. After coupling to the secondary winding, it is restored to a DC voltage by the DC-AC rectifier. Finally, it is inverted to the required single-phase industrial frequency 27.5kV AC voltage through the current-controlled inverter module 23. The high-frequency transformer 221 plays an isolation and voltage matching role, avoiding the introduction of additional traditional transformers in the main circuit, reducing costs, and achieving high-voltage direct hanging and large-capacity output. In specific implementation, the voltage level of the compensation circuit where the active compensation device 2 composed of a number of parallel-connected current conversion power units is located may not be limited to 27.5kV, but may be 6kV, 10kV, 27.5kV, etc. The active compensation device can adjust the capacity by increasing or decreasing the number of current conversion power units, and can also configure redundant units to improve the overall power supply reliability.
[0043] In this embodiment, the DC-AC rectifier may be a two-level, three-level or five-level rectifier, and the AC-DC inverter may be a two-level, three-level or five-level inverter.
[0044] Example 3
[0045] See also Figure 5 A DC interface 3 is provided at the output end of each voltage-controlled rectifier module and / or the output end of each AC-DC inverter, and the active compensation device 2 can be connected to the distributed power supply through the DC interface 3. In addition, the active compensation device 2 can also be connected to the distributed energy storage through the DC interface.
[0046] These DC interfaces 3 are distributed power supply interfaces configured on the DC side of the active compensation device. Through these DC interfaces, the access of distributed energy storage and distributed power supply is supported. The active compensation device can coordinate the power supply according to the load of the traction substation; with the help of distributed power supply, the power quality problem can be overcome. With the help of distributed energy storage, the braking energy generated during the regenerative braking of the train can be recovered and stored in the distributed energy storage. When the train is towed, the stored energy is released to the traction network for the train to use, so that the regenerated energy can be directly used in the traction power supply system, and various distributed energy storage, new energy generation, etc. can be flexibly and reliably integrated into the traction power supply system, so as to improve the utilization rate of line regenerative energy. At the same time, it can cut peaks and fill valleys and reduce the maximum load of the substation.
[0047] In this embodiment, the distributed power sources that can be connected can be new energy sources such as photovoltaics and wind turbines, and the distributed energy storage that can be involved includes batteries, supercapacitors and flywheel energy storage.
[0048] The three-phase-to-single-phase traction power supply system proposed in the utility model does not require a traditional matching transformer, occupies a small area, is convenient for modular production and on-site construction, is highly controllable, and the amplitude and phase of the voltage and current on the traction side are controllable. It can not only realize the same-phase power supply of the railway and solve the problems of power quality mainly caused by the negative sequence of the three-phase system caused by the load of the electric locomotive on the electrified railway, but also support the access of energy storage and distributed power sources, effectively improving the safe and economical operation level of the traction power supply system of the electrified railway.
[0049] Obviously, the above embodiments of the utility model are only examples for clearly explaining the utility model, and are not intended to limit the implementation methods of the utility model. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made on the basis of the above description. It is not necessary and impossible to list all the implementation methods here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the utility model should be included in the protection scope of the claims of the utility model.
Claims
1. An electrified railway three-phase to single-phase traction power supply system, characterized in that: It includes a traction transformer and an active compensation device; the traction transformer includes a primary winding, a first secondary winding and a second secondary winding, the primary winding is connected to a three-phase power grid, one end of the first secondary winding is directly connected to a railway traction network, and the other end is grounded; The active compensation device is composed of a plurality of parallel-connected current conversion power units, and the plurality of parallel-connected current conversion power units are provided with at least four connection interfaces, including a first interface, a second interface, a third interface and a fourth interface. One end of the second secondary winding is connected to the first interface, and the other end is connected to the second interface. The third interface is connected to a railway traction network, and the fourth interface is grounded.
2. The three-phase to single-phase traction power supply system for electrified railway according to claim 1, characterized in that: The other end of the second secondary winding is connected to the second interface through a high-voltage switch, and the third interface is connected to the railway traction network through a high-voltage switch.
3. The three-phase to single-phase traction power supply system for electrified railway according to claim 1, characterized in that: Each of the power conversion units includes: a voltage-controlled rectifier module, a high-frequency power control module and a current-controlled inverter module. The high-frequency power control module includes a DC-AC rectifier, a high-frequency transformer and an AC-DC inverter. The input end of the voltage-controlled rectifier module is connected to a single-phase industrial frequency AC voltage, the output end of the voltage-controlled rectifier module is connected to the input end of the DC-AC rectifier, the output end of the DC-AC rectifier is connected to the primary winding of the high-frequency transformer, the secondary winding of the high-frequency transformer is connected to the input end of the AC-DC inverter, and the output end of the AC-DC inverter is connected to the input end of the current-controlled inverter module.
4. The three-phase to single-phase traction power supply system for electrified railway according to claim 3 is characterized in that: The DC-AC rectifier is a two-level, three-level or five-level rectifier.
5. The three-phase to single-phase traction power supply system for electrified railway according to claim 3, characterized in that: The AC-DC inverter is a two-level, three-level or five-level inverter.
6. The three-phase to single-phase traction power supply system for electrified railway according to any one of claims 3 to 5, characterized in that: A DC interface is provided at the output end of each voltage-controlled rectifier module and / or the output end of each AC-DC inverter, and the active compensation device is connected to the distributed power source via the DC interface.
7. The three-phase to single-phase traction power supply system for electrified railway according to any one of claims 3 to 5, characterized in that: A DC interface is provided at the output end of each voltage-controlled rectifier module and / or the output end of each AC-DC inverter, and the active compensation device is connected to the distributed energy storage via the DC interface.
8. The three-phase to single-phase traction power supply system for electrified railway according to claim 6, characterized in that: The distributed power source includes photovoltaic and wind turbine.
9. The three-phase to single-phase traction power supply system for electrified railway according to claim 7, characterized in that: The distributed energy storage includes batteries, supercapacitors and flywheel energy storage.
10. The three-phase to single-phase traction power supply system for electrified railway according to any one of claims 1 to 5, 8 and 9, characterized in that: The traction transformer is a SCOTT transformer or a Vv transformer.