Alternating current traction power supply system and train power supply system

Abstract

The application discloses an alternating current traction network same-phase power supply system and a train power supply system, and the same-phase power supply system comprises a first traction transformer, a second traction transformer, a first current conversion device, a second current conversion device and an over-section device, the first traction transformer and the second traction transformer are arranged in two adjacent traction substations which are supplied with power in the same phase, the secondary winding of the first traction transformer and the secondary winding of the second traction transformer are connected in series to be used for converting three-phase high-voltage alternating current into single-phase alternating current, the secondary winding of the first traction transformer and the secondary winding of the second traction transformer are connected in parallel with the current conversion device to be used for comprehensively treating electric energy, and the over-section device is arranged in a section substation between the two adjacent traction substations which are supplied with power in the same phase to realize over-section. The application can realize same-phase power supply of railway traction substations, cancel electric phase separation of section substations, only need to set an electric section link, and can also realize comprehensive treatment of electric energy quality.

Description

Technical Field

[0001] This invention relates to the field of railway power supply equipment technology, and in particular to an AC traction network in-phase power supply system and a train power supply system. Background Technology

[0002] Traditional railway traction power supply systems use a single-phase AC, segmented, alternating phase sequence power supply structure, which can lead to power supply islands and thus the following problems:

[0003] 1. Electrical phase separation problem: Phase sequence rotation will result in electrical phase separation intervals on the traction power supply network. Therefore, electrical phase separation is required in both traction substations and sectioning stations in the traction power supply system. However, the electrical phase separation interval is one of the weakest links in the entire traction power supply system. It will not only cause loss of train speed and traction force, but may also generate overvoltage, and even cause electric arcs in the traction power supply network.

[0004] 2. Power quality issues: Power quality problems, mainly negative sequence, are prominent, which can cause three-phase imbalance in the public power grid. Moreover, with the commissioning of a large number of railway lines and high-speed locomotives, the impact of the traction power supply system on the power quality of the power system is becoming increasingly serious.

[0005] 3. Energy dispatch and management issues: Due to the segmented power supply structure, it is impossible to achieve optimized energy dispatch and intelligent management, resulting in a low overall energy efficiency level of the power supply system.

[0006] In summary, traditional traction power supply systems are no longer able to meet the development needs of high-speed and heavy-load rail transit. In-phase power supply systems can effectively solve the above-mentioned problems of traditional power supply systems and are an important development direction for current electrified railway traction power supply systems.

[0007] Chinese patent application CN113212253A discloses a through-type traction power supply system, which uses a SCOTT transformer and a phase-in-phase power supply device (CPD) to form a combined phase-in-phase power supply system. Specifically, the SCOTT transformer T-position provides the main power supply, while the M-position, connected in parallel with the CPD, provides secondary power supply and negative-sequence reactive power compensation. Electronic switching phase-separation devices are used in the substations to quickly connect and disconnect the main substation busbars. While this scheme achieves phase-in-phase power supply, it still requires phase-separation devices, thus still presenting a problem of the number of phase separations. Furthermore, the compensation converter requires a high voltage level and often necessitates the configuration of a matching transformer, increasing equipment costs. For example, if a low-voltage parallel scheme is adopted, the AC-DC-AC converter needs to be configured with matching transformers at both ends of the T-base and the power supply arm bus to step down the 27.5kV high voltage to 1kV or other low voltage standards. If a high-voltage parallel scheme is adopted, the AC-DC-AC converter is directly connected to the T-base through a cascaded step-up method. However, in order to reduce the technical and process difficulty of the converter, the voltage of the T-base is required to be 10kV, and a matching transformer is also required to connect to the 27.5kV side power supply arm bus for step-up. Summary of the Invention

[0008] The technical problem to be solved by this invention is: in view of the technical problems existing in the prior art, this invention provides an AC traction network in-phase power supply system and a train power supply system, which can realize in-phase power supply of railway traction substations, while eliminating the need to set up electrical phase separation links, and can also achieve comprehensive management of power quality.

[0009] To solve the above-mentioned technical problems, the technical solution proposed by this invention is as follows:

[0010] An AC traction network in-phase power supply system includes: a first traction transformer, a second traction transformer, a first converter, a second converter, and a section crossing device. The first traction transformer and the second traction transformer are respectively installed in two adjacent traction substations with in-phase power supply. The secondary windings of the first traction transformer and the second traction transformer are connected in series to convert three-phase high-voltage AC power into single-phase AC power. The secondary windings of the first traction transformer and the first converter are connected in parallel, and the secondary windings of the second traction transformer and the second converter are connected in parallel for comprehensive power management. The section crossing device is installed in a sectioning substation between two adjacent traction substations with in-phase power supply to control the connection of the energized section when the train passes through the section to achieve the section crossing.

[0011] Furthermore, the first converter and / or the second converter are cascaded AC-DC converters.

[0012] Furthermore, the DC side of the first converter and / or the second converter is also equipped with an energy storage device.

[0013] Furthermore, the energy storage device is used to recover and store the braking energy generated during regenerative braking of the train, and to release the stored energy to the traction network for the train's use when the train starts.

[0014] Furthermore, the first traction transformer and / or the second traction transformer are SCOTT transformers, and the M-type low-voltage winding and the T-type low-voltage winding of the SCOTT transformer are connected in series.

[0015] Furthermore, the section passing device includes an electronic switching valve and a train detection device for detecting the train's position. The electronic switching valve is located between the two power supply arms of the sectioning station. When the train detection device detects that the train has passed through the electric section, it controls the electronic switching valve to be turned on.

[0016] Furthermore, the train detection equipment includes a first detection component and a second detection component. The first detection component and the second detection component are respectively located in the areas where the train begins to enter the electric derailment section during forward and reverse travel. During forward travel, when the first detection component detects the passing of a train, it controls the electronic switching valve to be turned on; when the second detection component detects the passing of a train, it controls the electronic switching valve to be turned off. During reverse travel, when the second detection component detects the passing of a train, it controls the electronic switching valve to be turned on; when the first detection component detects the passing of a train, it controls the electronic switching valve to be turned off.

[0017] Furthermore, the electronic switching valve is a set of switching transistors connected in anti-parallel, and the switching transistors are any one of SCR, IGBT, IGCT and SiC.

[0018] A train power supply system includes multiple traction substations and sectioning stations, with adjacent traction substations having the same phase, and also includes an AC traction network in-phase power supply system as described above.

[0019] Compared with the prior art, the advantages of the present invention are as follows:

[0020] 1. This invention enables the two power supply arms of a railway traction substation to supply power in the same phase, while eliminating the phase separation link of the traction network. There is no need to set up an electrical phase separation device. Only one phase separation device needs to be set up in the section substation to meet the safety requirements of traction power supply. This can effectively avoid the problems caused by electrical phase separation and is conducive to the high-speed, smooth and safe operation of trains.

[0021] 2. This invention achieves three-phase to single-phase power supply by connecting the secondary windings of traction transformers in two adjacent traction substations with the same phase in series. Since the secondary windings are connected in series, the voltage amplitude of a single winding port is lower than that of the contact network voltage amplitude. This also reduces the voltage level of the compensation converter, thereby reducing the number of semiconductor devices connected in series and the equipment insulation level, and lowering equipment costs.

[0022] 3. By connecting a converter in parallel to the secondary windings of traction transformers in two adjacent traction substations with the same phase, this invention can also comprehensively manage the negative sequence, harmonics and reactive power of the traction power supply system, thereby meeting the power quality requirements. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structural principle of the AC traction network in-phase power supply system in this embodiment.

[0024] Figure 2 This is a schematic diagram of the main circuit topology of the in-phase traction substation in this embodiment.

[0025] Figure 3 This is a schematic diagram of the traction power supply voltage vector principle in this embodiment.

[0026] Figure 4 This is a schematic diagram of the structural principle of the segmentation device in this embodiment. Detailed Implementation

[0027] The present invention will be further described below with reference to the accompanying drawings and specific preferred embodiments, but this does not limit the scope of protection of the present invention.

[0028] As disclosed in this invention, unless the context clearly indicates otherwise, words such as "a," "an," "an," and / or "the" do not specifically refer to the singular and may also include the plural. The terms "first," "second," and similar terms used in this invention disclosure do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, words such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Words such as "connected" or "linked" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect.

[0029] like Figure 1As shown, the AC traction network in-phase power supply system of this embodiment includes: a first traction transformer T1, a second traction transformer T2, a first converter C1, a second converter C2, and a section crossing device. The first traction transformer T1 and the second traction transformer T2 are respectively installed in two adjacent traction substations (traction substations SS1 and SS2) with in-phase power supply. The secondary windings of the first traction transformer T1 and the second traction transformer T2 are connected in series to convert three-phase high-voltage AC power into single-phase AC power. The secondary windings of the first traction transformer T1 and the first converter C1 are connected in parallel, and the secondary windings of the second traction transformer T1 and the second converter C2 are connected in parallel for comprehensive power management. The section crossing device is installed in the sectioning post (SP) between two adjacent traction substations with in-phase power supply to control the connection of the energized section when the train passes through the section to achieve the section crossing.

[0030] This embodiment, through the aforementioned system, enables the two power supply arms of a railway traction substation to supply power in the same phase. Furthermore, since the contact network voltage supplied by adjacent traction substations is in phase, the phase-separation link in the traction network can be eliminated, eliminating the need for electrical phase separation. Only one phase-separation device is required at the sectioning station to meet the safety requirements of traction power supply, effectively avoiding problems caused by electrical phase separation and promoting high-speed, smooth, and safe train operation. Figure 1 As shown, since the voltages of the power supply arms A and B on both sides of the section are basically in phase, it is sufficient to set up an electrical separation section between power supply arms A and B to meet the safety requirements of traction power supply, without the need to set up an electrical separation phase (there is a neutral zone) between power supply arms A and B to achieve electrical isolation.

[0031] Meanwhile, in this embodiment, the secondary windings of the traction transformers (first traction transformer T1 and second traction transformer T2) in two adjacent traction substations with the same phase are connected in series for output, which can realize the conversion of three-phase to single-phase power supply. Since the secondary windings are connected in series for output, the voltage amplitude of a single winding port is lower than the voltage amplitude of the contact network. This can also reduce the voltage level of the compensation converter. For example, if the voltage amplitude of a single winding port is lower than the voltage amplitude of the contact network (27.5kV), the number of semiconductor devices connected in series and the insulation level of the equipment can be reduced, thereby reducing the number of matching transformers, improving system efficiency, and reducing equipment costs. In the parallel connection of converter devices (first converter C1 and second converter C2) on the secondary windings of the traction transformers (first traction transformer T1 and second traction transformer T2) in two adjacent traction substations with the same phase, negative sequence, reactive power and harmonic compensation can be achieved. This can comprehensively manage the negative sequence, harmonics and reactive power of the traction power supply system, meet the power quality requirements, and thus comprehensively solve the problems of excessive phase separation, low power quality and low power supply efficiency in the traction power supply system.

[0032] In this embodiment, the first converter C1 and the second converter C2 are cascaded AC-DC converters. Cascaded AC-DC converters achieve high-voltage, high-capacity power conversion through the cascading connection of multiple power units. A cascaded H-bridge topology can be used, with each H-bridge module including a DC power supply and an inverter circuit. By controlling the switching state of each H-bridge module, multi-level output can be achieved, thereby reducing harmonic content and improving output voltage quality. It is understood that the first converter C1 and the second converter C2 can also use other types of converter equipment according to actual needs. A cascaded three-level system is preferred, but two-level or other multi-level systems can also be used. The first converter C1 and the second converter C2 can use converter equipment with the same structure or converter equipment with different structures. The power electronic devices can be IGBTs, IGCTs, or SiCs. The first converter C1 and the second converter C2 can be directly connected or connected via a transformer for step-down, depending on actual requirements.

[0033] In this embodiment, energy storage devices are also provided on the DC side of the first converter C1 and the second converter C2. For example, an energy storage device can be connected to the DC side of a cascaded AC-DC converter to form an energy storage type high-voltage cascaded converter. This energy storage device is used to recover and store the braking energy generated during regenerative braking of the train, and to release the stored energy to the traction network for train use when the train starts. This allows the braking energy generated during regenerative braking to be recovered and stored in the energy storage device according to the load conditions of the traction transformer, and then released to the traction network for train use when the train starts, making full use of regenerative energy and avoiding energy waste. By setting up an energy storage device, peak shaving and valley filling of the traction load can also be performed, further reducing the capacity requirements and load sequence of the traction transformer.

[0034] Optionally, a high-power energy storage converter can be used to achieve power compensation and charge / discharge control based on the load conditions of the traction transformer, thereby effectively managing negative sequence, optimizing demand, and improving the utilization rate of regenerative energy. It is understood that the energy storage device can employ various types of energy storage equipment such as flywheels, supercapacitors, and energy storage batteries, and the specific configuration can be determined according to actual needs.

[0035] Optionally, considering the constraints of grid imbalance standards, the capacity requirements of the cascaded converters can be reduced by optimizing the partial compensation capacity configuration and modulation strategy of the first converter C1 and the second converter C2, thereby further improving the economic practicality of the system.

[0036] In this embodiment, the first traction transformer T1 and the second traction transformer T2 are SCOTT transformers. The low-voltage windings of the M and T sections of the SCOTT transformers are connected in series to realize the conversion of three-phase to single-phase power supply. At the same time, the low-voltage windings of the M and T sections of the SCOTT transformers are connected in parallel with the converter devices (first converter C1 and second converter C2) to comprehensively achieve the comprehensive management of negative sequence, harmonics and reactive power in the traction power supply system. The Scott transformer consists of two single-phase transformers: the M-type (Main Transformer) and the T-type (Teaser Transformer). The primary winding of the M-type transformer is connected to two phases of the three-phase power supply (e.g., phase B and phase C), forming a horizontally placed winding. The secondary winding outputs a single-phase voltage to supply power to one power supply arm. The primary winding of the T-type transformer is connected at one end to another phase of the three-phase power supply (e.g., phase A) and at the other end to the midpoint O of the M-type transformer, forming a vertically placed winding. The secondary winding outputs another single-phase voltage, 90° out of phase with the output voltage of the M-type transformer, to supply power to another power supply arm.

[0037] like Figure 1 As shown, the first converter C1 and the second converter C2 each include two energy storage type high-voltage cascaded converters. The low-voltage windings of the M and T sections of the first traction transformer T1 are connected in series, and the low-voltage windings of the M and T sections of the second traction transformer T2 are also connected in series, realizing the conversion of three-phase to single-phase power supply. The low-voltage windings of the M and T sections of the first traction transformer T1 are each connected in parallel with an energy storage type high-voltage cascaded converter, which can comprehensively realize negative sequence, reactive power, and harmonic compensation. Since the two secondary windings of the SCOTT transformer are connected in series for output, the voltage amplitude of a single winding port is lower than the voltage amplitude of the contact network. This also reduces the voltage level of the compensation converter, the number of semiconductor devices connected in series, and the equipment insulation level, thereby reducing equipment costs.

[0038] Understandably, the voltage rating of SCOTT transformers and contact networks can be determined according to specific usage conditions. For example, the three-phase power grid voltage can be 220kV or 110kV, or 35kV or 10kV, and the contact network voltage rating can be the conventional 27.5kV standard or the 10kV standard.

[0039] like Figure 2 , Figure 3 As shown, in a SCOTT transformer, connecting the end of the high-voltage winding of one transformer to the center of another high-voltage winding forms a T-connected three-phase winding. The two low-voltage windings on the secondary side (M-side and T-side) are both ordinary single-phase windings. Connecting the low-voltage windings of M-side and T-side in series for output conversion achieves a three-phase to single-phase output. In this case, the voltage relationship on the low-voltage side of the transformer can be expressed as:

[0040]

[0041] in, This represents the output voltage of the SCOTT transformer in series. This indicates the voltage at the M-type base of the SCOTT transformer. This indicates the voltage at the T-type junction of the SCOTT transformer.

[0042] Therefore, by connecting the two low-voltage windings on the secondary side of the SCOTT transformer in series, a three-phase to single-phase output can be achieved. However, the input current on the primary side of the transformer is still unbalanced. In this embodiment, by connecting high-voltage cascaded converters (first converter C1 and second converter C2) in parallel to the low-voltage windings of the M and T seats, negative sequence, reactive power and harmonic compensation can be achieved in a comprehensive manner.

[0043] It is understandable that, in addition to using SCOTT transformers, the first traction transformer T1 and the second traction transformer T2 may also use other types of transformers according to actual needs.

[0044] To achieve shock-free phase transition of the train and avoid arcing caused by differences in voltage and phase (due to different loads on power supply arm A and power supply arm B) on both sides of the segment anchor zone, this embodiment sets up a phase transition device in the section to facilitate the train's phase transition. Specifically, as shown... Figure 4 As shown, the section crossing device includes an electronic switching valve and train detection equipment for detecting the train's position. The electronic switching valve is located between the two power supply arms of the section crossing. When the train detection equipment detects that the train has passed through the section crossing, it controls the electronic switching valve to open. Through short-term bilateral power supply, the train can pass through the section crossing without impact, ensuring high-speed, smooth, and safe operation. Specifically, the electronic switching valve can use a set of switching transistors connected in anti-parallel. The preferred switching transistors are SCR thyristors, but they can also be implemented using power electronic devices such as IGBTs / IGCTs / SiCs.

[0045] In this embodiment, the train detection equipment specifically includes a first detection component and a second detection component. The first and second detection components are respectively located in the areas where trains begin to enter the electrical sub-section during forward and reverse travel. For example, the first detection component is located in the area where trains begin to enter the electrical sub-section during forward travel, and the second detection component is located in the area where trains leave the electrical sub-section. When the first detection component detects a train passing by, it controls the electronic switching valve to be turned on; when the second detection component detects a train passing by, it controls the electronic switching valve to be turned off. During reverse travel, when the second detection component detects a train passing by, it controls the electronic switching valve to be turned on; when the first detection component detects a train passing by, it controls the electronic switching valve to be turned off. This ensures that during forward and reverse travel, the electronic switching valve is only turned on when the system detects a train passing through the electrical sub-section, and the sub-section is directly connected for a short period of time. This achieves trains passing through the sub-section without impact, avoiding the generation of an uncontrollable balancing current in the traction network over a long period of time, which would affect the safe operation of the power system and traction power supply system.

[0046] Taking a train moving from power supply arm B to power supply arm A as an example, if Figure 4 As shown, the first detection component is arranged at position J2 and the second detection component is arranged at position J1. The electronic switching valve adopts a set of anti-parallel connected SCRs. The control logic of the system is as follows:

[0047] (1) When the first detection component detects that the train has reached the J2 position, the electronic switching valve (SCR) is turned on, so that the train can pass through the section without power interruption and without impact.

[0048] (2) When the second detection component detects that the train has arrived at position J1, the electronic switching valve (SCR) closes and enters standby mode.

[0049] In summary, this embodiment, through the aforementioned AC traction network phase-to-phase power supply system, can achieve three-phase to single-phase output, while eliminating the electrical phase separation at the substation outlet. The section only needs to set up a section-crossing device as an electrical section to meet the safety requirements of traction power supply. Furthermore, the section-crossing device enables the traction network on both sides to form a short-term bilateral power supply when the train passes through the electrical section, thus achieving a train-free passage through the section.

[0050] The train power supply system in this embodiment includes multiple traction substations and sectioning stations. The phases of two adjacent traction substations are the same, and it also includes the AC traction network in-phase power supply system as described above.

[0051] It is understood that the method described in this embodiment can be executed by a single device, such as a computer or server, or it can be applied to a distributed scenario where multiple devices cooperate to complete the task. In a distributed scenario, one of the multiple devices may execute only one or more steps of the method described in this embodiment, and the multiple devices interact to complete the method. The processor can be implemented using a general-purpose CPU, microprocessor, application-specific integrated circuit, or one or more integrated circuits, and is used to execute relevant programs to implement the method described in this embodiment. The memory can be implemented using read-only memory (ROM), random access memory (RAM), static storage devices, and dynamic storage devices. The memory can store the operating system and other applications. When the method described in this embodiment is implemented through software or firmware, the relevant program code is stored in the memory and called and executed by the processor.

[0052] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Therefore, any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention should fall within the protection scope of the present invention.

Claims

1. A synchronous power supply system for AC traction networks, characterized in that, include: The system comprises a first traction transformer, a second traction transformer, a first converter, a second converter, and a section crossing device. The first and second traction transformers are respectively located in two adjacent traction substations with the same phase power supply. The secondary windings of the first and second traction transformers are connected in series to convert three-phase high-voltage AC power into single-phase AC power. The secondary windings of the first and second traction transformers are connected in parallel with the first converter and the secondary windings of the second traction transformers are connected in parallel with the second converter for comprehensive power management. The section crossing device is located in a sectioning substation between two adjacent traction substations with the same phase power supply to control the connection of the energized section crossing when the train passes through the section crossing.

2. The AC traction network in-phase power supply system according to claim 1, characterized in that, The first converter and / or the second converter are cascaded AC-DC converters.

3. The AC traction network in-phase power supply system according to claim 1, characterized in that, The first converter and / or the second converter are further provided with energy storage devices on their DC sides.

4. The AC traction network in-phase power supply system according to claim 3, characterized in that, The energy storage device is used to recover and store the braking energy generated during regenerative braking of the train, and to release the stored energy to the traction network for the train's use when the train starts.

5. The AC traction network in-phase power supply system according to claim 1, characterized in that, The first traction transformer and / or the second traction transformer are SCOTT transformers, and the low-voltage winding of the M-type SCOTT transformer is connected in series with the low-voltage winding of the T-type SCOTT transformer.

6. The AC traction network in-phase power supply system according to any one of claims 1 to 5, characterized in that, The section passing device includes an electronic switching valve and a train detection device for detecting the train's position. The electronic switching valve is located between the two power supply arms of the section. When the train detection device detects that the train has passed through the electric section, it controls the electronic switching valve to be turned on.

7. The AC traction network in-phase power supply system according to claim 6, characterized in that, The train detection equipment includes a first detection component and a second detection component. The first detection component and the second detection component are respectively located in the areas where the train enters the electric derailment section during forward and reverse travel. During forward travel, when the first detection component detects the passing of a train, it controls the electronic switching valve to be turned on; when the second detection component detects the passing of a train, it controls the electronic switching valve to be turned off. During reverse travel, when the second detection component detects the passing of a train, it controls the electronic switching valve to be turned on; when the first detection component detects the passing of a train, it controls the electronic switching valve to be turned off.

8. The AC traction network in-phase power supply system according to claim 6, characterized in that, The electronic switching valve is a set of switching transistors connected in anti-parallel, and the switching transistors are any one of SCR, IGBT, IGCT and SiC.

9. A train power supply system, comprising multiple traction substations and sectioning stations, wherein adjacent traction substations have the same phase, characterized in that, It also includes the AC traction network in-phase power supply system as described in any one of claims 1 to 8.

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