Railway multi-source input power supply

Abstract

The utility model discloses a railway multi-source input type power supply relates to track traffic power supply technical field. The power supply architecture takes the alternating current network as the main power supply, and takes the wind power, photovoltaic, lithium battery as the standby power supply, and each energy is accessed direct current power bus through corresponding converter, introduces super capacitor and converter to realize lithium battery energy management and bus voltage disturbance suppression, adopts multi -machine parallel unidirectional DC / AC converter to supply power for all used load, and sets up bypass switch to realize power grid direct power supply backup. The converter control constructs double -loop control loop under dq0 rotation coordinate system, and according to the power supply system state, switches rectification mode, grid -connected inverter mode, local load inverter mode, realizes net side current unit power factor control, new energy redundant energy feedback, load uninterrupted power supply under fault. The utility model improves the power supply reliability, and helps new energy consumption simultaneously, is applicable to the power supply system of railway signal and communication etc. primary load.

Description

Technical Field

[0001] This utility model relates to the field of rail transit power supply technology, specifically a multi-source input power supply for railways. Background Technology

[0002] The power supply for primary loads such as railway signaling and communication systems generally adopts a dual-line 10kV power supply. The system mainly consists of two 10kV power supplies: a through-line (integrated through-line) and a self-closing (primary through-line). During normal operation, power is supplied by the through-line (integrated through-line). When the through-line (integrated through-line) loses power, power is supplied by the self-closing (primary through-line). During operation, if the through-line (integrated through-line) loses power, a large number of primary loads, such as railway signals and switch machines, need to switch to the self-closing (primary through-line) power supply. In this case, the operating unit will, based on the actual operating conditions, appropriately disconnect some loads with backup power supplies, which may adversely affect the normal operation of primary load equipment such as railway signaling and communication systems. Utility Model Content

[0003] The purpose of this invention is to provide a multi-source input power supply for railways to solve the problems mentioned in the background art.

[0004] To achieve the above objectives, this utility model provides the following technical solution:

[0005] Railway multi-source input power supplies include:

[0006] Main power supply unit: It is an AC power grid and serves as the main power supply for primary loads such as railway signaling and communication.

[0007] Backup energy units: including wind power equipment, photovoltaic equipment and lithium battery packs, serve as backup power sources when the main power supply unit loses power or load demand increases;

[0008] Converter group: includes converters 1 to 6, wherein:

[0009] Converter 1 is a single-phase DC / DC converter. Its input terminal is connected to the photovoltaic device, and its output terminal is connected to the DC power bus. It is used to convert the DC power output by the photovoltaic device into DC form that matches the DC power bus voltage.

[0010] Converter 2 is a unidirectional AC / DC converter. Its input terminal is connected to the wind power equipment, and its output terminal is connected to the DC power bus. It is used to convert the AC power output by the wind power equipment into DC power.

[0011] Converter 3 is a bidirectional DC / DC converter. Its input terminal is connected to the lithium battery pack, and its output terminal is connected to the DC power bus. It is used to realize the charging and discharging control of the lithium battery pack and the auxiliary control of the DC power bus voltage.

[0012] Converter 4 is a grid-side bidirectional AC / DC converter. Its input terminal is connected to the AC grid, and its output terminal is connected to the DC power bus. It is used to realize bidirectional power conversion between the AC grid and the DC power bus.

[0013] Converter 5 is a bidirectional DC / DC converter. Its input end is connected to the supercapacitor bank, and its output end is connected to the DC power bus, forming an energy management unit used to suppress disturbances in the DC power bus voltage.

[0014] Converter 6 is a unidirectional DC / AC converter group with a multi-machine parallel structure. Its input terminal is connected to the DC power bus, and its output terminal is connected to the load used for signal and communication. It is used to convert the DC power from the DC power bus into AC power to supply power to the load. In the unidirectional DC / AC converter group, one converter operates in inverter voltage control mode, and the other converters operate in harmonic current control mode.

[0015] Bypass switch: Both ends are connected to the AC power grid and the load respectively, and are used to connect the direct power supply circuit between the AC power grid and the load when the unidirectional DC / AC converter group fails;

[0016] Monitoring unit: It is connected to the control section of converter 1 to converter 6 via the control bus, and is used to realize the status monitoring of each converter and issue control commands.

[0017] Furthermore, the AC power grid is a 10kV dual-line power grid, including a through line (integrated through line) and a self-closing line (first-level through line). During normal operation, the through line supplies power, and when the through line loses power, the self-closing line serves as a backup main power supply.

[0018] Furthermore, the supercapacitor bank employs high-power-density electrochemical supercapacitors to quickly smooth out voltage disturbances on the DC power bus caused by load fluctuations or new energy output fluctuations.

[0019] Furthermore, the monitoring unit includes a data acquisition module, a mode decision module, and an instruction issuance module; the data acquisition module is used to collect AC grid voltage, DC bus voltage, output current of each converter, power of the load used, and power output of new energy sources; the mode decision module determines the power supply system status based on the collected data and determines the operating mode of the bidirectional AC / DC converter on the grid side; the instruction issuance module is used to send control instructions to each converter.

[0020] Compared with the prior art, the beneficial effects of this utility model are:

[0021] 1. Significantly improved power supply reliability: Constructing a multi-source power supply system of "AC grid + wind power + photovoltaic + lithium battery" avoids the single-source defects of traditional dual-line power supply; the dual backup of multi-machine parallel DC / AC converter and bypass switch ensures uninterrupted power supply to the loads used (especially signal and communication level loads) without the need to disconnect the load;

[0022] 2. Significantly enhanced capacity for renewable energy absorption: Wind power and photovoltaic power are directly connected to the DC bus, enabling efficient utilization of clean energy; grid-connected inverter mode can feed excess renewable energy back to the grid, avoiding energy waste and meeting the "dual carbon" target;

[0023] 3. Excellent control precision and power quality: Dual-loop control in the dq0 rotating coordinate system, combined with decoupling control and grid voltage feedforward, achieves unity power factor of grid-side current, stable bus voltage and precise control of inverter output voltage; harmonic current control mode of multi-machine parallel DC / AC converter effectively compensates for load harmonics and improves power quality;

[0024] 4. Strong system flexibility and adaptability: The monitoring unit can automatically switch the converter working mode according to the grid status, new energy output and load demand to adapt to different operating scenarios; the coordinated energy management of supercapacitors and lithium batteries extends the service life of lithium batteries and reduces system operation and maintenance costs. Attached Figure Description

[0025] Figure 1 A diagram showing the power supply structure for traction substations with various energy sources;

[0026] Figure 2 Diagram of the power system architecture used;

[0027] Figure 3 This is a block diagram of the grid-side bidirectional AC / DC converter control. Detailed Implementation

[0028] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are merely one circuit embodiment of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present utility model.

[0029] Please see Figure 1This is a multi-source power supply for railways, enabling diverse backup power options for the power supply system, improving system reliability, and facilitating the integration of new energy sources. In the diagram, the AC power grid is the primary power source, with wind power, photovoltaic power, and lithium batteries serving as backup power. Each energy source is converted to DC via corresponding converters (converters 1-4) and connected to the DC power bus. Simultaneously, a supercapacitor and converter 5 are introduced to manage the energy of the lithium batteries and suppress DC bus voltage disturbances. Converter 6 converts the DC power from the DC power bus to AC, providing uninterrupted AC power to the loads of the traction substation. Furthermore, the control sections of each converter are connected to a monitoring unit via a control bus to monitor and control the status of each converter.

[0030] To improve the reliability of power supply to traction substations and address the issue of renewable energy integration, this utility model proposes the following... Figure 2 The diagram illustrates a power supply architecture for loads using a combination of various energy sources. The AC grid converts AC to DC via a bidirectional AC / DC converter, supplying it to the DC bus. A unidirectional DC / AC converter then converts the DC power from the DC bus back to AC, providing AC power to the loads. To improve load reliability, multiple unidirectional DC / AC converters are connected in parallel, with one operating in inverter voltage control mode and the others in harmonic current control mode. Photovoltaic, wind power, and lithium batteries serve as backup energy sources, converting their output power to DC via corresponding converters and connecting it to the DC bus. Photovoltaic power is supplied via single-phase... The DC / DC converter converts DC power of one amplitude to DC power of another amplitude and sends it to the DC bus; the wind turbine uses a unidirectional AC / DC converter to convert the wind turbine's AC power to DC and connect it to the DC bus; the lithium battery uses a bidirectional DC / DC converter to connect to the DC bus, enabling battery charging and discharging and control of the bus voltage; the supercapacitor + bidirectional DC / DC converter serves as an energy management unit to suppress load disturbances to the bus voltage; when the unidirectional inverter on the load side fails, the bypass switch opens, and the grid directly supplies power to the load.

[0031] The control block diagram of the grid-side bidirectional AC / DC converter is as follows: Figure 3 As shown in the figure, the main circuit is a three-phase four-wire structure, including a three-phase AC power grid (the three-phase voltages are e). a e b and e c The system includes a neutral point (O), a three-phase AC / DC converter, a three-phase DC / AC converter, the traction substation's load, and bidirectional thyristors directly connected to the power grid and load. The three-phase AC / DC converter consists of three inductors L1, each connected to a three-phase power grid, a three-phase half-bridge circuit 1 composed of IGBT devices, and positive and negative DC bus capacitors C. dcThe three-phase inductor currents of the three-phase AC / DC converter are i a i b and i c The positive and negative DC bus voltages are U and U, respectively. dcp and U dcn The total bus voltage is U dc The three-phase DC / AC converter includes a three-phase half-bridge circuit 2 composed of IGBT devices, three filter inductors L2, and three filter capacitors C2. The voltage across the filter capacitors is the applied load voltage, which is u. ao u bo and u co .

[0032] For the control of the bidirectional AC / DC converter on the grid side, this invention constructs a control loop in the dq0 rotating coordinate system. Therefore, the three-phase grid voltage e in the abc stationary coordinate system is... a e b and e c Three-phase inductor current i a i b and i c The three-phase voltage u on the load side ao u bo and u co The abc / dq0 component is converted to the dq0 component in the rotated coordinate system by the rotation coordinate transformation module, which are e d e q 、e0,i d i q , i0, and u do u qo u 0o The rotation coordinate transformation angle is θ = ωt, where ω is the fundamental angular frequency.

[0033] Depending on the operating mode of the grid-side bidirectional AC / DC converter, this converter corresponds to three control modes: DC bus voltage control mode, inverter output power control mode, and inverter output voltage control mode. Each control mode employs a dual-loop control system. The inner loop is a current control loop, while the outer loop uses different control methods depending on the converter's operating mode. The converter operates in three modes based on the different states of the power supply system:

[0034] Mode 1: Rectification mode. When the power grid is normal, the bidirectional AC / DC converter on the grid side operates in rectification mode.

[0035] Mode 2: Grid-connected inverter mode. When the grid and the unidirectional DC / AC converter on the load side are normal, and the power of the renewable energy source is greater than the power of the load, the bidirectional AC / DC converter on the grid side operates in grid-connected inverter control mode. Renewable energy sources such as photovoltaic and wind power provide energy to the load, and excess energy is fed back to the grid.

[0036] Mode 3: Local load inverter mode. When the power grid fails and all unidirectional DC / AC converters on the load side fail, in order to improve the power supply reliability of the load, the bidirectional thyristor is turned on to put the bidirectional AC / DC converter on the grid side into inverter mode and control the inverter output voltage. At this time, the DC bus voltage is maintained by the lithium battery unit.

[0037] The control methods for the grid-side bidirectional AC / DC converter under the three operating modes are as follows:

[0038] 1) Mode 1: Rectification Mode

[0039] In rectification mode, the outer loop includes total voltage control and voltage equalization control. For the DC total voltage control loop, the DC bus voltage command U*dc and the total bus voltage U dc The difference is calculated, and the output is processed by the PI controller G. UPI Its output serves as the command signal i*d for the d-axis current control loop. To achieve DC bus voltage balancing, a voltage equalization control loop is introduced to balance the voltage difference U between the positive and negative DC buses. dcp -U dcn As a feedback signal, the difference between it and 0 is calculated, and the output is processed by the PI controller G. UPI Its output serves as the command signal i*0 for the 0-axis current control loop. In this mode, the command i*q for the q-axis current control loop is set to 0 to achieve unity power factor control of the grid-side current.

[0040] 2) Mode 2: Grid-connected inverter mode

[0041] When the grid-side bidirectional AC / DC converter operates in grid-connected inverter control mode, the outer loop includes an active power control loop and a reactive power control loop. For the active power control loop, the active power command P* and the active power output P (P=u) of the grid-side bidirectional AC / DC converter are... do i d The difference is calculated, and the output is processed by the PI controller G. WPI Its output serves as the command signal i*d for the d-axis current control loop; for the reactive power control loop, the reactive power command Q* and the reactive power Q (Q=u) output from the grid-side bidirectional AC / DC converter are used. qo i q The difference is calculated, and the output is processed by the PI controller G. WPI Its output serves as the command signal i*q for the q-axis current control loop; in this mode, the command i*0 for the 0-axis current loop is set to 0.

[0042] 3) Mode 3: Local Load Inversion Mode

[0043] The outer loop includes three control loops: d-axis voltage, q-axis voltage, and 0-axis voltage. For the d-axis voltage control loop, the d-axis voltage command u* do and the applied load-side d-axis voltage u do The difference is calculated, and the output is processed by the PI controller G. VPI Its output serves as the command signal i*d for the d-axis current control loop; for the q-axis voltage control loop, the q-axis voltage command u*qo and the applied load-side q-axis voltage u qo The difference is calculated, and the output is processed by the PI controller G. VPI Its output serves as the command signal i*q for the q-axis current control loop; the 0-axis voltage command u*0o and the 0-axis voltage u on the load side are used. 0o The difference is calculated, and the output is processed by the PI controller G. VPI Its output serves as the command signal i*0 for the 0-axis current control loop.

[0044] The operating mode of the bidirectional AC / DC converter on the grid side is determined by the switching mode selection switch based on the status of the power supply system.

[0045] The current inner loop control structure consists of d-axis current component inner loop control, q-axis current component inner loop control, and 0-axis current component inner loop control. For d-axis current component inner loop control, the current command i*d is compared with the sampled current i. d The difference is calculated, and the output is processed by the PI controller G. CPI To achieve decoupled control of the dq-axis current components, the q-axis current component i q Multiply by ωL1, subtract the output from the PI controller output, and then multiply by the sampled d-axis component e of the mains voltage. d The control loop is configured to suppress the impact of grid voltage disturbances on the d-axis control loop by introducing d-axis grid voltage feedforward, and its output serves as the modulated signal d-axis component u*d; for the q-axis current component inner loop control, the current command i*q is modulated by the sampled current i q The difference is calculated, and the output is processed by the PI controller G. CPI To achieve decoupled control of the dq-axis current components, the d-axis current component i d Multiply by ωL1, sum the output with the output of the PI controller, and then sum with the sampled q-axis component e of the mains voltage. q The control loop is configured to suppress the impact of grid voltage disturbances on the q-axis control loop by introducing q-axis grid voltage feedforward, and its output serves as the modulated signal q-axis component u*q. For the 0-axis current component inner loop control, the difference between the current command i*0 and the sampled current i0 is calculated, and the output is processed by the PI controller G. CPIThe output is summed with the sampled 0-axis grid voltage component e0. By introducing 0-axis grid voltage feedforward, the influence of grid voltage disturbances on the 0-axis control loop is suppressed. Its output serves as the 0-axis modulation signal u*0. The modulation signals u*d, u*q, and u*0 are fed into the inverse rotation converter module dq0 / abc, with a rotation angle of θ, to obtain the three-phase modulation voltages u*a, u*b, and u*c. These are then fed into the sinusoidal pulse width modulation (SPWM) stage to obtain the control signals for the three-phase half-bridge circuit IGBT devices, thereby controlling the bidirectional AC / DC converter on the grid side.

[0046] It will be apparent to those skilled in the art that this invention is not limited to the details of the foregoing exemplary embodiments, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of this invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within this invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0047] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A railway multi-source input power supply, characterized in that, include: Main power supply unit: It is an AC power grid and serves as the main power supply for primary loads such as railway signaling and communication. Backup energy units: including wind power equipment, photovoltaic equipment and lithium battery packs, serve as backup power sources when the main power supply unit loses power or load demand increases; Converter group: includes converters 1 to 6, wherein: Converter 1 is a grid-side bidirectional AC / DC converter. Its input terminal is connected to the AC grid, and its output terminal is connected to the DC power bus. It is used to realize bidirectional power conversion between the AC grid and the DC power bus. Converter 2 is a unidirectional AC / DC converter. Its input terminal is connected to the wind power equipment, and its output terminal is connected to the DC power bus. It is used to convert the AC power output by the wind power equipment into DC power. Converter 3 is a single-phase DC / DC converter. Its input terminal is connected to the photovoltaic device, and its output terminal is connected to the DC power bus. It is used to convert the DC power output by the photovoltaic device into DC form that matches the DC power bus voltage. Converter 4 is a bidirectional DC / DC converter. Its input terminal is connected to the lithium battery pack, and its output terminal is connected to the DC power bus. It is used to realize the charging and discharging control of the lithium battery pack and the auxiliary control of the DC power bus voltage. Converter 5 is a bidirectional DC / DC converter. Its input end is connected to the supercapacitor bank, and its output end is connected to the DC power bus, forming an energy management unit used to suppress disturbances in the DC power bus voltage. Converter 6 is a unidirectional DC / AC converter group with a multi-machine parallel structure. Its input terminal is connected to the DC power bus, and its output terminal is connected to the load used for signal and communication. It is used to convert the DC power of the DC power bus into AC power to supply power to the load. In the unidirectional DC / AC converter group, one converter operates in inverter voltage control mode, and the other converters operate in harmonic current control mode. Bypass switch: Both ends are connected to the AC power grid and the load respectively, and are used to connect the direct power supply circuit between the AC power grid and the load when the unidirectional DC / AC converter group fails; Monitoring unit: It is connected to the control section of converter 1 to converter 6 via the control bus, and is used to realize the status monitoring of each converter and issue control commands.

2. The railway multi-source input power supply according to claim 1, characterized in that, The AC power grid is a 10kV double-line power grid, including a through line and an automatic shut-off line. During normal operation, the through line supplies power, and when the through line loses power, the automatic shut-off line serves as a backup main power supply.

3. The railway multi-source input power supply according to claim 1, characterized in that, The supercapacitor bank uses high-power-density electrochemical supercapacitors to quickly smooth out voltage disturbances on the DC power bus caused by load fluctuations or fluctuations in new energy output.

4. The railway multi-source input power supply according to claim 3, characterized in that, The monitoring unit includes a data acquisition module, a mode decision module, and an instruction issuance module. The data acquisition module is used to collect AC grid voltage, DC bus voltage, output current of each converter, power of the load, and power output of new energy sources. The mode decision module determines the power supply system status based on the collected data and determines the working mode of the bidirectional AC / DC converter on the grid side. The instruction sending module is used to send control instructions to each converter.

5. The railway multi-source input power supply according to claim 3, characterized in that, The main circuit of the grid-side bidirectional AC / DC converter is a three-phase four-wire structure, including a three-phase AC grid, a three-phase AC / DC converter, a three-phase DC / AC converter, the traction substation's load, and bidirectional thyristors directly connecting the grid and the load. The three-phase AC / DC converter includes three inductors L1, each connected to the three-phase grid, a three-phase half-bridge circuit 1 composed of IGBT devices, and positive and negative DC bus capacitors C. dc The three-phase inductor currents of the three-phase AC / DC converter are i a i b and i c The positive and negative DC bus voltages are U and U, respectively. dcp and U dcn The total bus voltage is U dc The three-phase DC / AC converter includes a three-phase half-bridge circuit 2 composed of IGBT devices, three filter inductors L2, and three filter capacitors C2. The voltage across the filter capacitors is the load voltage, which is u. ao u bo and u co。

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