New energy AC / DC hybrid power supply system applied to rail transit

Abstract

The invention discloses a new energy alternating current and direct current hybrid power supply system applied to rail transit. The system comprises an alternating current unit, a direct current unit, an alternating current and direct current connection unit and an energy storage unit, the direct current unit is connected to the DC1500V bus, the DC1500V bus is connected to the main bus through the alternating current and direct current connecting unit, the alternating current unit is connected to the main bus in a single bus wiring mode, and the energy storage unit is connected with the main bus. A rail transit power supply system is accessed in an alternating current and direct current hybrid + energy storage mode, so that effective utilization of new energy resources is realized; according to the invention, the DC part can effectively solve the problem of photovoltaic grid connection of a photovoltaic power generation site in an area close to a rail transit station; the alternating current part can effectively solve the photovoltaic grid-connected problem that a high-voltage alternating current line needs to be adopted for electric energy transmission in an area, far away from a rail transit station, of a photovoltaic power generation site; the energy storage part can effectively solve the problem that normal photovoltaic power generation is affected by off-grid operation and the like when photovoltaic power is connected to a direct-current bus of a rail transit station through a high-voltage alternating-current line.

Description

Technical Field

[0001] This invention relates to the field of AC / DC power supply technology, and more specifically to a new energy AC / DC hybrid power supply system for rail transit. Background Technology

[0002] my country possesses abundant renewable energy resources such as wind and solar power, and its rail transit infrastructure and surrounding spaces offer ample space for renewable energy development and utilization. The rail transit power supply voltage is DC 1500V. For plots of land within the station suitable for installing photovoltaic (PV) power generation equipment, DC grid connection can be used. However, when these plots are far from the transportation station, DC power supply results in significant voltage loss, reducing energy conversion efficiency. Therefore, it is necessary to consider using high-voltage AC lines to transmit the generated electricity from the PV system to the transportation station. When the PV power generation system is directly connected to the DC 1500V busbar within the rail transit station, the 10kV PV system operates off-grid, affecting its normal operation. Summary of the Invention

[0003] The present invention proposes a new energy AC / DC hybrid power supply system for rail transit, which can at least solve one of the technical problems in the background art.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: A new energy AC / DC hybrid power supply system for rail transit includes: an AC unit, a DC unit, an AC / DC connection unit, and an energy storage unit; The DC unit is connected to the DC1500V bus, which is connected to the main bus via an AC / DC connection unit. The AC unit is connected to the main bus using a single bus connection method, and the energy storage unit is connected to the main bus.

[0005] Furthermore, the AC unit of this invention includes: a photovoltaic module, an inverter, and a step-up transformer; The DC power generated by the photovoltaic modules is converted into low-voltage AC power by an inverter. The low-voltage AC power is then converted into high-voltage AC power by a step-up transformer and connected to the high-voltage AC bus. The high-voltage AC bus supplies power to the nearest AC load and is also connected to the power grid. The high-voltage AC busbar adopts a single busbar connection method and is equipped with photovoltaic incoming cabinet, busbar PT cabinet, reactive power compensation device cabinet, station service transformer cabinet, energy storage incoming cabinet, and photovoltaic outgoing cabinet.

[0006] Furthermore, the DC unit of the present invention includes a photovoltaic module, a combiner box, and a DC converter: The photovoltaic modules are connected to the combiner box. The DC power generated by the combiner box is then output as a stable 1500V DC power by a DC / DC converter with MPPT tracking function, and then connected to the 1500V DC bus. The DC bus supplies power to the nearest DC load and is also connected to the original DC1500V bus of the rail transit electrical system.

[0007] Furthermore, the AC / DC connection unit structure of the present invention is as follows: The high-voltage AC bus converts the high-voltage AC power to low-voltage AC power through a step-down transformer. The low-voltage AC power is then converted to 1500V DC power through a bidirectional converter PCS and connected to the 1500V DC bus.

[0008] As can be seen from the above technical solution, this invention fully utilizes renewable energy to construct a clean, green, and highly resilient rail transit energy system. It integrates wind, solar, and energy storage systems into the rail transit power supply system using a hybrid AC / DC + energy storage model, based on geographical conditions and electricity demand, thereby achieving effective utilization of new energy resources. The DC component effectively solves the grid connection problem for photovoltaic power generation sites located close to rail transit stations; the AC component effectively solves the grid connection problem for photovoltaic power generation sites located far from rail transit stations, requiring high-voltage AC lines for power transmission; and the energy storage component effectively solves the problem of off-grid operation affecting normal photovoltaic power generation when photovoltaic systems are connected to the DC bus of rail transit stations via high-voltage AC lines.

[0009] This invention can reduce carbon emissions, reduce energy costs, promote the integrated development of rail transit and renewable energy, help optimize the energy structure of transportation systems, promote the development of green, low-carbon, and environmentally friendly transportation systems, and provide innovative and application ideas for the integration of renewable energy and rail transit power supply systems. Attached Figure Description

[0010] Figure 1 This is a structural block diagram of the new energy AC / DC hybrid power supply system of the present invention. Detailed Implementation

[0011] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0012] like Figure 1 As shown in this embodiment, the new energy AC / DC hybrid power supply system applied to rail transit includes: an AC unit, a DC unit, an AC / DC connection unit, and an energy storage unit. The DC unit is connected to the DC1500V bus, which is connected to the main bus via an AC / DC connection unit. The AC unit is connected to the main bus using a single bus connection method, and the energy storage unit is connected to the main bus.

[0013] The AC unit consists of photovoltaic modules, an inverter, and a step-up transformer. The DC power generated by the photovoltaic modules is converted into low-voltage AC power by the inverter, and the low-voltage AC power is then converted into high-voltage AC power by the step-up transformer and connected to the high-voltage AC bus. The high-voltage AC bus can supply power to nearby AC loads or be connected to the power grid.

[0014] The high-voltage AC busbar adopts a single busbar connection method and is equipped with photovoltaic incoming cabinet, busbar PT cabinet, reactive power compensation device cabinet, station service transformer cabinet, energy storage incoming cabinet, and photovoltaic outgoing cabinet.

[0015] The DC unit consists of photovoltaic modules, a combiner box, and a DC converter. The photovoltaic modules are connected to the combiner box, and the DC power generated by the combiner box is output as a stable 1500V DC power by a DC / DC converter with MPPT tracking function, which is then connected to the 1500V DC bus. The DC bus can supply power to nearby DC loads and is also connected to the existing 1500V DC bus of the rail transit electrical system.

[0016] The AC / DC connection unit structure is as follows: the high-voltage AC bus converts the high-voltage AC power to low-voltage AC power through a step-down transformer, and the low-voltage AC power is then converted to 1500V DC power through a bidirectional converter (PCS) and connected to the 1500V DC bus.

[0017] The energy storage unit consists of an energy storage incoming line cabinet, an energy storage step-up transformer, a grid-type PCS (converter), an energy storage battery management system, an energy storage energy management system, and an energy storage battery compartment. During peak solar power generation at midday, the generated electricity charges the energy storage system. Once fully charged, the stored energy is fed back to the DC 1500V bus. At night, when solar power is not generating, the energy storage system discharges. The grid-type PCS can be internally configured with voltage parameters to output stable voltage and frequency, simulating grid operating parameters and providing strong support to the grid, ensuring normal solar power generation during midday.

[0018] The integration of rail transit systems with new energy sources in power supply methods exhibits certain intermittency and fluctuations. Utilizing a hybrid AC / DC system combined with electrochemical energy storage can effectively mitigate the impact of the system on the power grid, improve energy utilization efficiency, and ensure the safe and reliable operation of the power supply system. (See also...) Figure 1 Power supply system diagram.

[0019] The AC / DC hybrid power supply system proposed in this invention comprises three parts: a traditional AC power supply method, a DC power supply method, and an electrochemical energy storage system. Through electrical connection, the reliability of the power supply network is improved.

[0020] The main working process of the new energy AC / DC hybrid power supply system for rail transit of this invention is as follows: 1. When the photovoltaic AC / DC part is not generating electricity, the energy storage system works normally as a voltage source. Through the internal settings of the grid-type PCS, the parameters of the 10kV power grid are simulated. The energy storage PCS works in the discharge state, and the voltage, frequency, power angle, etc. are consistent with the parameters of the conventional 10kV power grid. 2. The energy storage system operates normally as a voltage source, providing transient voltage support for the photovoltaic AC inverter. 3. When the sunlight is good, the photovoltaic DC section works normally. The DC power generated by the photovoltaic modules is sent to the upstream DC1500V bus through the combiner box to achieve grid connection and provide power to the load on the DC1500V bus side. 4. When the sunlight is good, the inverter of the photovoltaic AC section needs to monitor the grid parameters on the 10kV bus side in real time. If the grid parameters cannot be monitored, the inverter stops working; after the 10kV grid parameters are monitored, the inverter starts working, the grid parameters on the 10kV bus section are maintained, and the AC section starts generating electricity. 5. After the photovoltaic AC section is working normally, the grid-type PCS changes from the discharge state to the charging and discharging state. While the energy storage provides transient voltage support to the photovoltaic AC section inverter, the photovoltaic power generation prioritizes charging the energy storage battery. After the energy storage battery is fully charged, the photovoltaic power is transmitted to the 10kV bus section. 6. The 10kV photovoltaic outgoing line cabinet converts 10kV AC power into 1500V DC power through a step-down rectifier integrated machine, and sends it to the DC1500V bus section of the rail transit to provide power to the load on the DC1500V bus side.

[0021] In summary, by fully utilizing renewable energy to construct a clean, green, and highly resilient rail transit energy system, wind, solar, and energy storage systems can be integrated into the rail transit power supply system using a hybrid AC / DC + energy storage model, based on geographical conditions and electricity demand, thereby achieving effective utilization of new energy resources. The DC component of this invention effectively solves the grid connection problem for photovoltaic power generation sites located close to rail transit stations; the AC component effectively solves the grid connection problem for photovoltaic power generation sites located far from rail transit stations, requiring high-voltage AC lines for power transmission; and the energy storage component effectively addresses the issue of off-grid operation and other disruptions to normal photovoltaic power generation when photovoltaic systems are connected to the DC bus of rail transit stations via high-voltage AC lines.

[0022] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0023] The various embodiments in this specification are described in a related manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, the system embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions of the method embodiments.

[0024] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A new energy AC / DC hybrid power supply system applied to rail transit, characterized in that, include: AC unit, DC unit, AC / DC connection unit, energy storage unit; The DC unit is connected to the DC1500V bus, which is connected to the main bus via an AC / DC connection unit. The AC unit is connected to the main bus using a single bus connection method, and the energy storage unit is connected to the main bus.

2. The new energy AC / DC hybrid power supply system for rail transit according to claim 1, characterized in that, The AC unit includes: photovoltaic modules, inverter, and step-up transformer; The DC power generated by the photovoltaic modules is converted into low-voltage AC power by an inverter. The low-voltage AC power is then converted into high-voltage AC power by a step-up transformer and connected to the high-voltage AC bus. The high-voltage AC bus supplies power to the nearest AC load and is also connected to the power grid. The high-voltage AC busbar adopts a single busbar connection method and is equipped with photovoltaic incoming cabinet, busbar PT cabinet, reactive power compensation device cabinet, station service transformer cabinet, energy storage incoming cabinet, and photovoltaic outgoing cabinet.

3. The new energy AC / DC hybrid power supply system for rail transit according to claim 1, characterized in that, The DC unit includes photovoltaic modules, combiner boxes, and DC converters. The photovoltaic modules are connected to the combiner box. The DC power generated by the combiner box is then output as a stable 1500V DC power by a DC / DC converter with MPPT tracking function, and then connected to the 1500V DC bus. The DC bus supplies power to the nearest DC load and is also connected to the original DC1500V bus of the rail transit electrical system.

4. The new energy AC / DC hybrid power supply system for rail transit according to claim 1, characterized in that, The AC / DC connection unit structure is as follows: The high-voltage AC bus converts the high-voltage AC power to low-voltage AC power through a step-down transformer. The low-voltage AC power is then converted to 1500V DC power through a bidirectional converter PCS and connected to the 1500V DC bus.

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