Power supply system and method based on flywheel energy storage device

Abstract

The invention provides a power supply system and method based on a flywheel energy storage device, and relates to the technical field of rail transit traction power supply, and the system comprises the flywheel energy storage device, an energy management module, a bidirectional converter, a DC traction network, an AC power grid and a medium-voltage network. The output side of the flywheel energy storage device comprises a first group of direct current contactors and a second group of direct current contactors; the flywheel energy storage device is connected with the direct-current traction network through a first group of direct-current contactors, a first flywheel isolating switch and a first group of switches in sequence; the flywheel energy storage device is connected with the alternating-current power grid through a second group of direct-current contactors, a second flywheel isolating switch, a second group of switches and a bidirectional converter in sequence; the direct-current traction network is connected with the alternating-current power grid through a third group of direct-current contactors, a second group of switches and a bidirectional converter; and the energy management module is connected with the flywheel energy storage device, the bidirectional converter, the direct-current traction network, the alternating-current power grid and the medium-voltage network. The uninterrupted power supply of the power supply system is ensured, and the power supply reliability is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of rail transit traction power supply, and in particular to a power supply system and method based on a flywheel energy storage device. Background Art

[0002] Rail transit system trains generate a lot of braking energy when starting and stopping due to their large mass. The current mainstream rail train energy recovery methods include feedback type and storage type. The feedback type braking energy regeneration utilization method mainly uses an inverter feedback device to return excess electrical energy to the 10kV / 35kV medium voltage network for use by AC loads; the storage type braking energy regeneration utilization method mainly uses battery energy storage devices, supercapacitor energy storage devices, flywheel energy storage devices, etc. Its basic working principle is to absorb the braking energy fed back to the traction network when the train brakes, and supply the energy consumption when the train starts or runs. Both of these regenerative braking energy recovery methods can reduce power loss and improve energy utilization.

[0003] Flywheel energy storage devices are widely used in rail train braking energy recovery due to their high power density and fast response speed. When the train is braking, the flywheel accelerates its rotation to store energy; when the train is starting or accelerating, the flywheel releases energy by reducing its speed; the flywheel energy storage device can not only realize braking energy recovery, but also quickly eliminate the impact of voltage fluctuations, waveform changes, frequency fluctuations and interference of the power grid.

[0004] However, in the existing power supply system using flywheel energy storage devices in urban rail transit substations, the DC750V / 1500V DC traction network and the AC 400V AC power grid mainly obtain power from the 10kV / 35kV medium voltage network through distribution transformers. There is no direct or indirect energy relationship between them, and the entire power supply system does not form a closed loop; therefore, when the AC400V AC power grid fails, only the battery-type emergency power supply can supply power to the corresponding load, and the power quality is poor. In addition, with the increase in the volume of trains in the later period, when the regenerative braking energy is added to the DC traction network, the regenerative braking energy recovery device will face the problem of limited energy absorption due to the control strategy or its own capacity limitation, and it will not be able to fully absorb the regenerative braking energy of the train, resulting in the increase of the DC traction network voltage, causing voltage disturbance, and unable to ensure the uninterrupted power supply of the power supply system, which has an adverse effect on the power supply system. In severe cases, it will cause failure or downtime of sensitive equipment, thereby affecting the normal operation of electrical equipment, which may lead to major safety accidents and direct and indirect economic losses. Summary of the invention

[0005] The present invention provides a power supply system and method based on a flywheel energy storage device, which are used to solve the problem of poor power quality and inability to ensure uninterrupted power supply of the power supply system.

[0006] On the one hand, the present invention provides a power supply system based on a flywheel energy storage device, the system comprising: a flywheel energy storage device, an energy management module, a bidirectional converter, a DC traction network, an AC power grid and a medium voltage network; The output side of the flywheel energy storage device includes a first group of DC contactors and a second group of DC contactors; the flywheel energy storage device is connected to the DC traction network through the first group of DC contactors, the first flywheel isolating switch and the first group of switches in sequence; the flywheel energy storage device is connected to the AC power grid through the second group of DC contactors, the second flywheel isolating switch, the second group of switches and the bidirectional converter in sequence; The DC traction network is connected to the AC power grid via a third set of DC contactors, a second set of switches and the bidirectional converter; The energy management module is simultaneously connected to the flywheel energy storage device, the bidirectional converter, the DC traction network, the AC power grid and the medium voltage network.

[0007] Furthermore, the medium voltage network is connected to the DC traction network through a rectifier unit, and is connected to the AC power grid through a distribution transformer and a second switch.

[0008] Furthermore, when the system includes a plurality of the flywheel energy storage devices, the plurality of flywheel energy storage devices are connected in parallel, and each group of DC contactors is correspondingly connected to a flywheel isolating switch.

[0009] Furthermore, multiple flywheel energy storage devices are connected in parallel including: A first group of DC contactors of a plurality of flywheel energy storage devices are connected to a plurality of the first flywheel isolating switches correspondingly, and a plurality of the first flywheel isolating switches are connected in parallel to the DC traction network through the first group of switches; The second group of DC contactors of the plurality of flywheel energy storage devices are connected to the plurality of second flywheel isolating switches correspondingly, and the plurality of second flywheel isolating switches are connected in parallel to the bidirectional converter through the second group of switches.

[0010] Furthermore, the energy management module includes: A CAN communication unit, used to connect to each of the flywheel energy storage devices and perform electrical signal communication with the flywheel energy storage devices; A logic control unit, used for real-time monitoring of electrical signals of the DC traction network, the AC power grid and the medium voltage network, and for receiving electrical signals and sending charging and discharging instructions to the bidirectional converter; The control display unit is used to receive and display control instructions from the CAN communication unit and the logic control unit.

[0011] On the other hand, the present invention further proposes a power supply method for a power supply system based on a flywheel energy storage device as described in any one of the above, the method comprising: When the power supply system operates normally, the energy management module monitors the electrical signals of the flywheel energy storage device, the DC traction network, the AC power grid and the medium voltage network in real time; Determining whether the voltage of the AC power grid is abnormal; If the voltage of the AC power grid is abnormal, the power of the flywheel energy storage device is obtained and it is determined whether the power is less than a discharge threshold; if so, it indicates that the voltage of the AC power grid is normal, otherwise, the flywheel energy storage device is directly used to supply power to the AC power grid; If the voltage of the AC power grid is normal, obtaining the voltage of the DC traction network and determining whether the voltage is less than a starting voltage threshold of the flywheel energy storage device; If so, a discharge instruction is issued to the flywheel energy storage device, and the flywheel energy storage device is used to discharge to the DC traction grid; Otherwise, a charging instruction is sent to the flywheel energy storage device. During the charging process, the power of the flywheel energy storage device is continuously obtained and it is determined whether the power is less than the discharge threshold. If so, it means that the voltage of the AC power grid is normal. Otherwise, the bidirectional converter is used to power the AC power grid.

[0012] Furthermore, when the train line operates normally and the AC power grid is powered normally, the second group of DC contactors and the third group of DC contactors are in a disconnected state, the flywheel energy storage device receives the charging and discharging instructions issued by the energy management module, and an energy loop is formed between the flywheel energy storage device, the DC traction network and the train.

[0013] Furthermore, when the flywheel energy storage device cannot completely absorb the regenerative braking energy of the train, the first group of DC contactors is disconnected, the third group of DC contactors is closed, and the excess regenerative braking energy of the train is fed back to the AC power grid through the bidirectional converter for consumption by the electrical equipment on the AC power grid; The energy management module monitors the electrical signals of the DC traction network in real time and determines whether the train braking condition is completed; when the train braking condition is completed, the third group of DC contactors is disconnected and the first group of DC contactors is closed, and an energy circuit is formed again between the flywheel energy storage device, the DC traction network and the train.

[0014] Furthermore, when the train line operates normally but the power supply of the AC power grid is abnormal, the first group of DC contactors is disconnected and the third group of DC contactors is closed. The energy management module monitors the power of the flywheel energy storage device in real time. When the power is lower than the discharge threshold, the second group of DC contactors is closed, and the flywheel energy storage device is used as an emergency power supply alone to supply power to the AC power grid through the bidirectional converter.

[0015] Furthermore, when the train stops operating, the first switch, the first group of DC contactors, the first flywheel isolating switch, the first group of switches and the third group of DC contactors are in an open state, and the second switch, the second group of DC contactors, the second flywheel isolating switch and the second group of switches are in a closed state.

[0016] In general, the present invention provides a power supply system and method based on a flywheel energy storage device. The technical solution conceived by the present invention can achieve the following beneficial effects compared with the prior art: The power supply system established by the present invention includes a flywheel energy storage device, an energy management module, a bidirectional converter, a DC traction network, an AC power grid and a medium voltage network. When the power supply is normal, an energy loop is formed between the flywheel energy storage device, the DC traction network and the train, and the excess regenerative braking energy of the train can be fed back to the AC power grid through the bidirectional converter for consumption by the auxiliary machine in the station, thereby improving the quality of electric energy; and when the train line is operating normally and the AC power grid fails and cannot supply power normally and requires emergency power, the flywheel energy storage device can be used as a separate emergency power supply to supply power to the AC power grid to ensure the normal operation of the power supply system. In addition, the energy management module monitors the power of the flywheel energy storage device in real time. When the available power is lower than its own discharge threshold, the bidirectional converter can be used to supply power to the AC power grid to ensure the normal operation of the power supply system; not only the charging and discharging performance of the flywheel energy storage device is guaranteed, but also the uninterrupted power supply of the power supply system can be guaranteed regardless of whether the AC power grid is abnormal, thereby greatly improving the power supply reliability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 It is a schematic diagram of the system principle of a power supply system and method based on a flywheel energy storage device provided by the present invention; Figure 2 It is a schematic diagram of a system control method of a power supply system and method based on a flywheel energy storage device provided by the present invention. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings and embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0020] It should be noted that, in the description of the embodiments of the present invention, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a method, step or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such method, step or device. In the absence of further restrictions, the elements defined by the sentence "include a ..." do not exclude the existence of other identical elements in the method, step or device including the elements.

[0021] The present invention proposes a power supply system and method based on a flywheel energy storage device. With the increase of train traffic in the later period, when the regenerative braking energy recovery device cannot completely absorb the regenerative braking energy of the train, the flywheel energy storage device can collect and release the braking energy of the train on the DC side and take into account the emergency power supply of the equipment of the AC power grid, and establish an energy interaction channel between the regenerative braking energy and the AC power grid. When the flywheel energy storage device cannot completely absorb the regenerative braking energy of the train, the power supply system can feed back the excess electric energy to the AC power grid through a bidirectional converter for consumption by auxiliary machines in the station, so that the entire power supply system of urban rail transit forms a closed loop and improves the reliability of the entire power supply system. When the train line operates normally and the AC power grid fails and cannot supply power normally and needs emergency power, the flywheel energy storage device can be used as a separate emergency power supply to supply power to the AC power grid to ensure the normal operation of the power supply system.

[0022] In a first aspect, the present invention proposes a power supply system based on a flywheel energy storage device. Specifically, the system includes: a flywheel energy storage device, an energy management module, a bidirectional converter, a DC traction network, an AC power grid and a medium voltage network.

[0023] The output side of the flywheel energy storage device includes a first group of DC contactors and a second group of DC contactors; the flywheel energy storage device is connected to the DC traction network through the first group of DC contactors, the first flywheel isolating switch and the first group of switches in sequence; the flywheel energy storage device is connected to the AC power grid through the second group of DC contactors, the second flywheel isolating switch, the second group of switches and the bidirectional converter in sequence; the DC traction network is connected to the AC power grid through the third group of DC contactors, the second group of switches and the bidirectional converter; the energy management module is simultaneously connected to the flywheel energy storage device, the bidirectional converter, the DC traction network, the AC power grid and the medium voltage network.

[0024] It should be noted that the DC traction network is connected to the overhead contact network of the train through the first switch QF1; the medium voltage network is connected to the DC traction network through the rectifier unit, and is connected to the AC grid through the distribution transformer and the second switch QF2.

[0025] There may be one or more flywheel energy storage devices.

[0026] As an embodiment, when the system includes multiple flywheel energy storage devices, the multiple flywheel energy storage devices are connected in parallel, and each group of DC contactors is correspondingly connected to a flywheel isolation switch.

[0027] More specifically, multiple flywheel energy storage devices are connected in parallel, including: a first group of DC contactors of the multiple flywheel energy storage devices are connected to a corresponding plurality of first flywheel isolating switches, and the multiple first flywheel isolating switches are connected in parallel to the DC traction network through the first group of switches; a second group of DC contactors of the multiple flywheel energy storage devices are connected to a corresponding plurality of second flywheel isolating switches, and the multiple second flywheel isolating switches are connected in parallel to the bidirectional converter through the second group of switches.

[0028] As an embodiment, the energy management module includes a CAN communication unit, a logic control unit and a control display unit.

[0029] The CAN communication unit is used to connect each flywheel energy storage device and communicate electrical signals with each flywheel energy storage device; for example, each flywheel energy storage device includes a flywheel communication unit, and multiple flywheel communication units in multiple flywheel energy storage devices are simultaneously connected to the CAN communication unit.

[0030] The logic control unit is used to monitor the electrical signals of the DC traction network, AC power grid and medium voltage network in real time, and to receive electrical signals and send charging and discharging instructions to the bidirectional converter.

[0031] The control display unit is used to receive and display control instructions from the CAN communication unit and the logic control unit.

[0032] As a specific example, Figure 1As shown, it includes three flywheel energy storage devices. Each flywheel energy storage device has two groups of positive and negative DC contactors on the output side, that is, the output side of flywheel energy storage device 1# includes the first group of DC contactors KM1, KM2 and the second group of DC contactors KM7, KM8; the output side of flywheel energy storage device 2# includes the first group of DC contactors KM3, KM4 and the second group of DC contactors KM9, KM10; the output side of flywheel energy storage device 3# includes the first group of DC contactors KM5, KM6 and the second group of DC contactors KM11, KM12.

[0033] Among them, the first group of DC contactors KM1~KM6 is used to connect the DC+750 / 1500V bus and DC-750 / 1500V bus of the DC contactor; the second group of DC contactors KM7~KM12 is used to connect the AC400V bus of the AC power grid; when the system is working, only one group of DC contactors is allowed to be in the closed state.

[0034] Each group of DC contactors of each flywheel energy storage device is connected to a flywheel isolating switch at the upper end. That is, the first group of DC contactors KM1 and KM2 of flywheel energy storage device 1# is connected to the first flywheel isolating switch QS3, and the second group of DC contactors KM7 and KM8 is connected to the second flywheel isolating switch QS6; the first group of DC contactors KM3 and KM4 of flywheel energy storage device 2# is connected to the first flywheel isolating switch QS4, and the second group of DC contactors KM9 and KM10 is connected to the second flywheel isolating switch QS7; the first group of DC contactors KM5 and KM6 of flywheel energy storage device 3# is connected to the first flywheel isolating switch QS5, and the second group of DC contactors KM11 and KM12 is connected to the second flywheel isolating switch QS8.

[0035] The flywheel energy storage device is connected to the DC traction network through the first group of DC contactors, the first flywheel disconnectors and the first group of switches in sequence. For example, the first group of DC contactors is KM1~KM6; the first flywheel disconnectors are QS3~QS5; the first group of switches is QF3, QS1. The three first group of DC contactors KM1~KM6 are connected to the three first flywheel disconnectors QS3~QS5, and the three flywheel energy storage devices are connected to the DC traction network through the three first group of DC contactors KM1~KM6, the three first flywheel disconnectors QS3~QS5 and the first group of switches in sequence. The first flywheel disconnectors QS3~QS5 are connected in parallel to the DC+750 / 1500V busbar and DC-750 / 1500V busbar of the DC traction network through the first group of switches.

[0036] The flywheel energy storage device is connected to the AC power grid through the second group of DC contactors, the second flywheel isolating switches, the second group of switches and the bidirectional converter in sequence. For example, the second group of DC contactors is KM7~KM12; the second flywheel isolating switches are QS6~QS8; the second group of switches is QF4, QS2. The three second groups of DC contactors KM7~KM12 are connected to the three second flywheel isolating switches QS6~QS8, and the three flywheel energy storage devices are connected to the PCS bidirectional converter in sequence through the three second groups of DC contactors KM7~KM12, the three second flywheel isolating switches QS6~QS8 and the second group of switches, and then connected to the AC power grid by the PCS bidirectional converter. The second flywheel isolating switches QS6~QS8 are connected in parallel to the PCS bidirectional converter through the second group of switches QF4 and QS2, and then connected to the AC400V busbar of the AC power grid by the PCS bidirectional converter.

[0037] The DC traction network is connected to the AC grid through the third set of DC contactors, the second set of switches and the bidirectional converter. For example, the third set of DC contactors are KM13 and KM14; the second set of switches are QF4 and QS2. The DC+750 / 1500V busbar and DC-750 / 1500V busbar of the DC traction network are connected to the AC400V busbar of the AC grid through KM13, KM14, QF4, QS2 and PCS bidirectional converters.

[0038] The energy management module is used to monitor the electrical signals of the flywheel energy storage device, DC traction network, AC power grid and medium voltage network in real time.

[0039] The energy management module monitors the voltage signal of the AC400V bus of the DC traction network in real time, and sends charging and discharging instructions to the PCS bidirectional converter according to the voltage of the DC traction network. The PCS bidirectional converter then sends charging and discharging instructions to the flywheel energy storage device.

[0040] The energy management module monitors the voltage signals of the DC+750 / 1500V and DC-750 / 1500V buses of the AC power grid in real time, monitors the power of the flywheel energy storage device in real time, and issues charging and discharging instructions to the flywheel energy storage device according to the voltage signals of the DC traction network.

[0041] The energy management module monitors the medium voltage network 10kV / 35kV in real time and identifies the no-load voltage so as to control the operation of the flywheel energy storage device through the no-load voltage.

[0042] In a second aspect, the present invention proposes a power supply method based on a flywheel energy storage device. Specifically, Figure 2 As shown, the method includes: When the power supply system operates normally, the energy management module monitors the electrical signals of the flywheel energy storage device, DC traction network, AC power grid and medium voltage network in real time, and determines whether the voltage of the AC power grid is abnormal.

[0043] If the voltage of the AC grid is abnormal, the power of the flywheel energy storage device is obtained and it is determined whether the power is less than the discharge threshold; if so, it means that the voltage of the AC grid is normal, otherwise, the flywheel energy storage device is directly used to supply power to the AC grid; If the voltage of the AC grid is normal, the voltage of the DC traction grid is obtained and it is determined whether the voltage is less than the starting voltage threshold of the flywheel energy storage device; If yes, a discharge instruction is issued to the flywheel energy storage device, and the flywheel energy storage device is used to discharge to the DC traction grid; Otherwise, a charging instruction is sent to the flywheel energy storage device. During the charging process, the power of the flywheel energy storage device is continuously obtained and it is determined whether the power is less than the discharge threshold. If so, it means that the voltage of the AC power grid is normal. Otherwise, the bidirectional converter is used to supply power to the AC power grid.

[0044] The method for judging whether the voltage of the AC power grid is abnormal can be: when the root mean square value of the input voltage of the power supply system itself exceeds the allowable deviation range of the root mean square value of the input voltage preset by the flywheel energy storage device, it is judged that the voltage is abnormal; when the root mean square value of the input voltage of the power supply system itself recovers to within the allowable deviation range of the root mean square value of the input voltage preset by the flywheel energy storage device, it is judged that the voltage is normal.

[0045] When the RMS value of the input voltage of the power supply system itself exceeds the preset allowable deviation range of the RMS value of the input voltage of the flywheel energy storage device; that is, it means that the mains power supply voltage has voltage fluctuation problems such as voltage sag, voltage swell or short-term voltage interruption, the flywheel energy storage device switches to the flywheel energy storage device power supply mode in milliseconds, and the flywheel energy storage device provides continuous and uninterrupted power supply to the electrical equipment on the AC power grid through a bidirectional inverter.

[0046] When the RMS value of the input voltage of the power supply system itself returns to the preset RMS value of the input voltage of the flywheel energy storage device, the flywheel energy storage device switches to the rectification and inverter power supply mode in milliseconds. The AC input voltage is converted into DC through the rectifier of the flywheel energy storage device to charge the flywheel energy storage device. After the flywheel energy storage device is fully charged and reaches the rated speed, it enters the floating charge standby mode. At the same time, the flywheel energy storage device converts DC into AC through a bidirectional inverter to provide continuous and uninterrupted power supply for electrical equipment.

[0047] As an embodiment, when the train line operates normally and the AC power grid is powered normally, the second group of DC contactors and the third group of DC contactors are in a disconnected state, the flywheel energy storage device receives the charging and discharging instructions issued by the energy management module, and an energy loop is formed between the flywheel energy storage device, the DC traction network and the train.

[0048] For example, when the train line is operating normally and the AC power grid is operating normally, the second group of DC contactors KM7~KM12 and the third group of DC contactors KM13~KM14 are in the disconnected state, the first group of DC contactors KM1~KM6, all flywheel isolation switches QS1~QS8, the first switch QF1, the second switch QF2, the first group of switches QF3 and QS1, and the second group of switches QF4 and QS2 are in the closed state, and the flywheel energy storage device receives the charge and discharge action instructions issued by the energy management module, and an energy circuit is formed between the flywheel energy storage device, the DC traction network DC750 / 1500V and the train. In addition, the start threshold is a value higher than the no-load voltage.

[0049] Furthermore, when the flywheel energy storage device cannot completely absorb the regenerative braking energy of the train, the first group of DC contactors is disconnected and the third group of DC contactors is closed. The excess regenerative braking energy of the train is fed back to the AC power grid through the bidirectional converter to be consumed by the electrical equipment on the AC power grid. The energy management module monitors the electrical signals of the DC traction network in real time and determines whether the braking condition of the train is ended. When the braking condition of the train is ended, the third group of DC contactors is disconnected and the first group of DC contactors is closed. An energy loop is formed again between the flywheel energy storage device, the DC traction network and the train.

[0050] For example, when the flywheel energy storage device cannot fully absorb the train's regenerative braking energy, the first group of DC contactors KM1~KM6 is disconnected, and then the third DC contactors KM13~KM14 are closed. The excess regenerative braking energy of the train can be fed back to the AC400V bus of the AC power grid through the PCS bidirectional converter to be consumed by the 400V electrical equipment on the AC power grid. The energy management module monitors the voltage signal of the DC traction network in real time to determine whether the train braking condition has ended. When it has ended, the third group of DC contactors KM13~KM14 is disconnected, and the first group of DC contactors KM1~KM6 is closed. At this time, an energy loop is formed again between the flywheel energy storage device, the DC traction network DC750 / 1500V and the train.

[0051] As another embodiment, when the train line operates normally but the AC power grid is powered abnormally, the first group of DC contactors is disconnected and the third group of DC contactors is closed. The energy management module monitors the power of the flywheel energy storage device in real time. When the power is lower than the discharge threshold, the second group of DC contactors is closed, and the flywheel energy storage device is used as an emergency power supply alone to supply power to the AC power grid through a bidirectional converter.

[0052] When the train line operates normally but the AC power grid is abnormal, that is, the AC400V bus of the AC power grid is powered off due to a fault in the power supply equipment at the grid port, or the energy management module detects that the AC400V bus of the AC power grid has voltage fluctuations, waveform changes, frequency fluctuations, and interference.

[0053] For example, when the train line operates normally but the AC power grid is abnormally powered, the first group of DC contactors KM1~KM6 connecting the flywheel energy storage device to the DC750 / 1500V bus of the DC traction network is disconnected, and the third group of DC contactors KM13~KM14 connecting the PCS bidirectional converter to the DC750 / 1500V bus of the DC traction network is closed, so that the electric energy of the DC traction network can supply the AC400V bus of the AC power grid through the third group of DC contactors and the PCS bidirectional converter.

[0054] The energy management module monitors the power of the flywheel energy storage device in real time. When the available power is lower than its own discharge threshold, the second group of DC contactors KM7~KM12 connected to the AC400V bus of the AC power grid are closed, and the full-power flywheel energy storage device is used as an emergency power supply alone. The AC400V bus of the AC power grid is powered by the second group of DC contactors, the second flywheel isolating switch, the second group of switches and the PCS bidirectional converter.

[0055] When the AC400V busbar of the AC power grid returns to normal, the second group of DC contactors KM7~KM12 connecting the flywheel energy storage device to the AC400V busbar are disconnected, and the first group of DC contactors KM1~KM6 connected to the DC750 / 1500V busbar of the DC traction network are closed. At this time, the energy circuit is re-formed between the flywheel energy storage device, the DC traction network DC750 / 1500V and the train.

[0056] Furthermore, when the train stops operating, the first switch, the first group of DC contactors, the first flywheel isolating switch, the first group of switches and the third group of DC contactors are in an open state, and the second switch, the second group of DC contactors, the second flywheel isolating switch and the second group of switches are in a closed state.

[0057] For example, when the line is shut down, QF1, KM1~KM6, QS3~QS5, QF3, QS1 and KM13~KM14 are in the disconnected state, QF2, KM7~KM12, QS6~QS7 and QF4, QS2 are in the closed state, and the flywheel energy storage device is connected to the AC400V busbar of the AC grid. When the AC grid is powered normally, the flywheel energy storage device is in the floating charge state.

[0058] In summary, the present invention not only ensures the charging and discharging performance of the flywheel energy storage device, but also greatly improves the power supply reliability of the system.

[0059] It should be noted that, for the above-mentioned various embodiments, for the sake of simplicity of description, they are all expressed as a series of action combinations, but those skilled in the art should be aware that the present application is not limited by the described order of actions, because according to the present application, certain steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also be aware that the embodiments described in the specification are all preferred embodiments, and the actions and modules involved are not necessarily required by the present application.

[0060] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0061] In the several embodiments provided in this application, it should be understood that the disclosed method or system can be implemented in other ways. For example, the above-described embodiments are only schematic, and the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed.

[0062] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0063] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0064] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable memory. Based on this understanding, the technical solution of the present application is essentially or the part that contributes to the prior art or the whole or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a memory, including a number of instructions for a computer device (which can be a personal computer, a server or a network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present application.

[0065] Those skilled in the art will appreciate that all or part of the various circuits in the above embodiments may be completed by entering a program to instruct related hardware, and the program may be stored in a computer-readable memory, which may include: a flash drive, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk, etc.

[0066] The above is only an exemplary embodiment of the present disclosure, and the scope of the present disclosure cannot be limited thereto. That is, any equivalent changes and modifications made according to the teachings of the present disclosure are still within the scope of the present disclosure. After considering the specification and practicing the disclosure here, those skilled in the art will easily think of the implementation scheme of the present disclosure. This application is intended to cover any modification, use or adaptation of the present disclosure, which follows the general principles of the present disclosure and includes common knowledge or customary technical means in the technical field not recorded in the present disclosure. The description and examples are regarded as exemplary only, and the scope and spirit of the present disclosure are defined by the claims.

[0067] The technical features of the above embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0068] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A power supply system based on a flywheel energy storage device, characterized in that: The system includes: a flywheel energy storage device, an energy management module, a bidirectional converter, a DC traction network, an AC power grid and a medium voltage network; The output side of the flywheel energy storage device includes a first group of DC contactors and a second group of DC contactors; the flywheel energy storage device is connected to the DC traction network through the first group of DC contactors, the first flywheel isolating switch and the first group of switches in sequence; the flywheel energy storage device is connected to the AC power grid through the second group of DC contactors, the second flywheel isolating switch, the second group of switches and the bidirectional converter in sequence; The DC traction network is connected to the AC power grid via a third set of DC contactors, a second set of switches and the bidirectional converter; The energy management module is simultaneously connected to the flywheel energy storage device, the bidirectional converter, the DC traction network, the AC power grid and the medium voltage network.

2. A power supply system based on a flywheel energy storage device according to claim 1, characterized in that: The medium voltage network is connected to the DC traction network through a rectifier unit, and is connected to the AC power grid through a distribution transformer and a second switch.

3. A power supply system based on a flywheel energy storage device according to claim 1, characterized in that: When the system includes a plurality of the flywheel energy storage devices, the plurality of flywheel energy storage devices are connected in parallel, and each group of DC contactors is correspondingly connected to a flywheel isolating switch.

4. A power supply system based on a flywheel energy storage device according to claim 3, characterized in that: Multiple flywheel energy storage devices connected in parallel include: A first group of DC contactors of a plurality of flywheel energy storage devices are connected to a plurality of the first flywheel isolating switches correspondingly, and a plurality of the first flywheel isolating switches are connected in parallel to the DC traction network through the first group of switches; The second group of DC contactors of the plurality of flywheel energy storage devices are connected to the plurality of second flywheel isolating switches correspondingly, and the plurality of second flywheel isolating switches are connected in parallel to the bidirectional converter through the second group of switches.

5. A power supply system based on a flywheel energy storage device according to claim 3, characterized in that: The energy management module comprises: A CAN communication unit, used to connect to each of the flywheel energy storage devices and perform electrical signal communication with each of the flywheel energy storage devices; A logic control unit, used for real-time monitoring of electrical signals of the DC traction network, the AC power grid and the medium voltage network, and for receiving electrical signals and sending charging and discharging instructions to the bidirectional converter; The control display unit is used to receive and display control instructions from the CAN communication unit and the logic control unit.

6. A power supply method for a power supply system based on a flywheel energy storage device according to any one of claims 1 to 5, characterized in that: The method comprises: When the power supply system operates normally, the energy management module monitors the electrical signals of the flywheel energy storage device, the DC traction network, the AC power grid and the medium voltage network in real time; Determining whether the voltage of the AC power grid is abnormal; If the voltage of the AC power grid is abnormal, the power of the flywheel energy storage device is obtained and it is determined whether the power is less than a discharge threshold; if so, it indicates that the voltage of the AC power grid is normal, otherwise, the flywheel energy storage device is directly used to supply power to the AC power grid; If the voltage of the AC power grid is normal, obtaining the voltage of the DC traction network and determining whether the voltage is less than a starting voltage threshold of the flywheel energy storage device; If so, a discharge instruction is issued to the flywheel energy storage device, and the flywheel energy storage device is used to discharge to the DC traction grid; Otherwise, a charging instruction is sent to the flywheel energy storage device. During the charging process, the power of the flywheel energy storage device is continuously obtained and it is determined whether the power is less than the discharge threshold. If so, it means that the voltage of the AC power grid is normal. Otherwise, the bidirectional converter is used to power the AC power grid.

7. A power supply method based on a flywheel energy storage device according to claim 6, characterized in that: When the train line operates normally and the AC power grid is powered normally, the second group of DC contactors and the third group of DC contactors are in a disconnected state, the flywheel energy storage device receives the charging and discharging instructions issued by the energy management module, and an energy loop is formed between the flywheel energy storage device, the DC traction network and the train.

8. A power supply method based on a flywheel energy storage device according to claim 7, characterized in that: When the flywheel energy storage device cannot completely absorb the regenerative braking energy of the train, the first group of DC contactors is disconnected, the third group of DC contactors is closed, and the excess regenerative braking energy of the train is fed back to the AC power grid through the bidirectional converter for consumption by the electrical equipment on the AC power grid; The energy management module monitors the electrical signals of the DC traction network in real time and determines whether the train braking condition is completed; when the train braking condition is completed, the third group of DC contactors is disconnected and the first group of DC contactors is closed, and an energy circuit is formed again between the flywheel energy storage device, the DC traction network and the train.

9. A power supply method based on a flywheel energy storage device according to claim 7, characterized in that: When the train line operates normally but the AC power grid is powered abnormally, the first group of DC contactors is disconnected and the third group of DC contactors is closed. The energy management module monitors the power of the flywheel energy storage device in real time. When the power is lower than the discharge threshold, the second group of DC contactors is closed, and the flywheel energy storage device is used as an emergency power supply alone to supply power to the AC power grid through the bidirectional converter.

10. A power supply method based on a flywheel energy storage device according to claim 9, characterized in that: When the train stops running, the first switch, the first group of DC contactors, the first flywheel isolating switch, the first group of switches and the third group of DC contactors are in the open state, and the second switch, the second group of DC contactors, the second flywheel isolating switch and the second group of switches are in the closed state.

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