CN-121984061-A - Online power conversion type mobile energy storage system and power conversion method thereof

Abstract

An on-line power conversion type mobile energy storage system and a power conversion method thereof are provided, wherein self-holding batteries in the system are connected into a direct current bus through a direct current converter, each group of power conversion batteries are connected into the direct current bus through 1 transfer switch, a power grid or load is connected into the direct current bus through an isolation transformer and an alternating current-direct current converter containing a solid switch, when the mobile energy storage system is off-grid, the alternating current-direct current converter with the solid switch on-off is connected with the alternating current bus according to alternating current voltage output by an alternating current load power control system, if an energy management unit sends out a power conversion battery withdrawal or input instruction, the direct current converter controls the direct current bus voltage to switch on or off the corresponding transfer switch, so that energy can be rapidly supplemented with the system in a seamless mode, and the continuous power supply capacity of the mobile energy storage system is improved.

Inventors

• ZHUANG JUN
• CAI XIAOFENG
• LI YUELONG
• Tang Congwei
• XUE JINHUA
• ZHANG WENBO
• DAI ZHENGZHOU
• YANG YILIN
• FAN CUNGANG
• CAI DELONG
• ZHU SHUAI
• YANG WEN
• WANG LEI
• Yan Shiye
• WANG QI
• WANG DESHUN
• ZHANG FEIFEI
• ZHOU CHEN
• GU ZHIJUN
• GAN LU

Assignees

• 国网上海市电力公司
• 国网上海能源互联网研究院有限公司

Dates

Publication Date

20260505

Application Date

20251211

Claims (10)

1. 1. An on-line power conversion type mobile energy storage system, comprising: The system comprises at least 1 group of self-holding batteries and DC/DC converters which are connected in series, a plurality of groups of battery-changing batteries and change-over switches which are connected in series, an energy management unit, an AC/DC converter containing a solid-state switch, an isolation transformer and a DC bus, wherein the self-holding batteries are connected to the DC bus through the DC/DC converters, each group of battery-changing batteries are connected to the DC bus through 1 change-over switch, a power grid or a load is connected to the DC bus through the isolation transformer and the AC/DC converter containing the solid-state switch, the AC/DC converter which is switched on or off by the solid-state switch is controlled to switch on or off the corresponding change-over switch according to the AC voltage when the energy management unit sends out the command of the battery-changing or the input command, and the AC/DC converter which is switched on or off by the solid-state switch is controlled to switch on or off the corresponding change-over switch when the energy storage system is connected to the grid.
2. 2. The on-line battery-operated mobile energy storage system of claim 1, wherein, When the mobile energy storage system is off-grid, when the SOC of the battery to be withdrawn from the battery replacement is not more than the preset lower limit, the energy management unit sends a battery replacement withdrawal instruction, the DC-DC converter operates in a voltage control mode, the difference value between the DC bus voltage and the port voltage of the battery to be withdrawn from the battery replacement is controlled to be 0, so that the output current of the battery to be withdrawn from the battery replacement is 0, and the energy management unit sends an on-off instruction to a corresponding change-over switch.
3. 3. The on-line battery-operated mobile energy storage system of claim 2, wherein, When the mobile energy storage system is off-grid, when the SOC of the battery to be charged is not less than the preset upper limit, the energy management unit sends a battery charging instruction to the DC-DC converter, the DC-DC converter operates in a voltage control mode, the difference between the voltage of the DC bus and the operating voltage of the battery to be charged is controlled to be 0, and the voltages at two ends of the switch of the battery to be charged are synchronized so as to close the corresponding switch.
4. 4. The on-line battery-operated mobile energy storage system of claim 1, wherein, When the mobile energy storage system is connected with the grid, when the SOC of the battery to be withdrawn is not more than the preset lower limit, the energy management unit sends a battery withdrawal instruction, the DC-DC converter operates in a current control mode, and the DC bus current is controlled according to the DC bus voltage controlled by the AC-DC converter, so that the output current of the battery to be withdrawn is 0, and the corresponding change-over switch is turned on.
5. 5. The on-line battery-operated mobile energy storage system of claim 4, wherein, When the mobile energy storage system is connected with the grid, when the SOC of the battery to be charged is not less than the preset upper limit, the energy management unit sends a battery charging instruction to the DC-DC converter, the DC-DC converter operates in a current control mode, and the current of the DC bus is controlled according to the DC bus voltage controlled by the AC-DC converter, so that the current of a branch where the battery to be charged is located is 0, and a corresponding change-over switch is closed.
6. 6. The on-line battery-operated mobile energy storage system of claim 1, wherein, The battery is connected with one end of the change-over switch through the fast plug-in interface, and the other end of the change-over switch is connected with the direct current bus.
7. 7. A power conversion method of an online power conversion type mobile energy storage system, which is applicable to the online power conversion type mobile energy storage system as claimed in any one of claims 1to 6, and is characterized by comprising the following steps: when the mobile energy storage system leaves the network, the solid-state switch-on AC/DC converter controls the DC bus voltage to turn on or turn off the corresponding change-over switch according to the AC voltage output by the AC load power control system if the energy management unit sends out a command for exiting or putting in the battery; When the mobile energy storage system is connected with the grid, the solid-state switch-closed alternating-current-direct-current converter controls the direct-current bus voltage according to the alternating-current grid voltage, and if the energy management unit sends out a command for withdrawing or throwing the battery, the direct-current converter controls the direct-current bus current to open or close the corresponding change-over switch.
8. 8. The method for changing power of an on-line power-changing mobile energy storage system according to claim 7, comprising the steps of: step 1, acquiring an opening and closing state of a solid-state switch, acquiring alternating current load power and executing step 2 when the solid-state switch is opened, acquiring alternating current grid voltage and executing step 4 when the solid-state switch is closed; Step 2, according to the alternating voltage output by the alternating load power control system, when the SOC of the battery to be withdrawn is not more than the preset lower limit, the energy management unit sends out a battery withdrawal instruction, the direct-current converter operates in a voltage control mode, the difference between the direct-current bus voltage and the port voltage of the battery to be withdrawn is controlled to be 0, so that the output current of the battery to be withdrawn is 0, and the energy management unit sends out an on-off instruction to a corresponding change-over switch; Step 3, after the battery to be charged is withdrawn, when the SOC of the battery to be charged is not less than the preset upper limit, the energy management unit sends a battery charging instruction to the DC-DC converter, the DC-DC converter operates in a voltage control mode, and the difference between the voltage of the DC bus and the operating voltage of the battery to be charged is controlled to be 0, so that the voltages at two ends of a change-over switch of the battery to be charged are synchronous, and the corresponding change-over switch is closed; Step 4, the AC-DC converter controls the DC bus voltage according to the AC power grid voltage, when the SOC of the battery to be withdrawn is not more than the preset lower limit, the energy management unit sends out a battery withdrawal command, the DC-DC converter operates in a current control mode, and controls the DC bus current according to the DC bus voltage controlled by the AC-DC converter so as to enable the output current of the battery to be withdrawn to be 0, so as to switch on the corresponding switch; And 5, after the battery replacement is withdrawn, when the SOC of the battery to be placed in the battery replacement is not less than the preset upper limit, the energy management unit sends a battery replacement input instruction to the DC-DC converter, the DC-DC converter operates in a current control mode, and the current of the DC bus is controlled according to the DC bus voltage controlled by the AC-DC converter, so that the current of a branch where the battery to be placed in the battery replacement is placed is 0, and a corresponding change-over switch is closed.
9. 9. A terminal comprises a processor and a storage medium, and is characterized in that: The storage medium is used for storing instructions; The processor being operative according to the instructions to perform the steps of the method of any one of claims 7-8.
10. 10. A computer readable storage medium, on which a computer program is stored, characterized in that the program, when being executed by a processor, implements the steps of the method according to any of claims 7-8.

Description

Online power conversion type mobile energy storage system and power conversion method thereof Technical Field The invention belongs to the technical field of mobile power application, and provides a topological structure, composition configuration and operation method of an online power conversion type mobile energy storage system. Background The power-exchanging type mobile energy storage system is a key means for power conservation and emergency power supply, however, insufficient cruising ability has become a key bottleneck for restricting the large-scale popularization and application of the power-exchanging type mobile energy storage system. In the prior art, the power conversion mode relies on shutdown power conversion, and an effective topology design of online power conversion is lacking, so that the whole energy storage system must be interrupted in operation when a battery is replaced, and the requirements of power conservation and emergency scenes for continuous and stable power supply for more than 8 hours cannot be met; the system can not fundamentally solve the problem of online power change, when a battery pack needs to be replaced, the battery pack still needs to be shut down for operation or intermittently powered off for replacement, the existing power change system has the defects of compatibility and generality, the battery packs of different brands and different models have differences in size, interfaces, electrical parameters and the like, the power change equipment can only be adapted to the battery packs of specific types, cross-brands and cross-model universal power change is difficult to realize, when the battery packs of different sources need to be called for replenishment, the compatibility problem can lead to low power change efficiency, even the power change can not be completed, the emergency response capability of the system is seriously influenced, the existing power change operation mostly needs manual assistance, the labor cost is increased, the problems of large operation error, long power change time and the like exist, the risk of power interruption is further aggravated due to uncertainty of manual operation in emergency, the high efficiency and stability of the power change process can not be ensured, the information of the residual electric quantity, the health state and the like of the battery packs to be replaced and the performance parameters of the battery packs are required to be accurately understood in the power change process, the power change process can be ensured, the accuracy of the existing power change system can not be easily monitored, and the power change system can not be completely influenced by the system is well, and the power change system is well monitored, and the power change system can not be easily has the power change accuracy is well, and the power change system can not be monitored, and has the power change performance is well has the power change condition has the performance requirements, the battery is not physically replaced by a special power-saving and transition unit only through a mechanical structure, an independent voltage supporting and power transition module is not arranged, so that power supply is required to be interrupted during power replacement, a new energy automobile and a heavy truck can only replace a whole set of batteries in a single cluster during power replacement, replacement and replacement of multiple batteries without power failure cannot be realized, and multiple requirements of online power replacement of a power grid are difficult to meet. Disclosure of Invention The invention provides an online power conversion type mobile energy storage system and a power conversion method thereof, which solve the problem of continuous voyage of the mobile energy storage system through a power conversion mode, effectively improve the continuous operation capability of the mobile energy storage system, and can efficiently complete the power protection operation and improve the operation capability of the power distribution network when long-time power distribution operation exists during power distribution network load power protection, platform dynamic capacity increase and emergency power supply, and the provided power conversion mode can realize rapid energy source supplement and seamless system switching and obviously improve the continuous power supply capability and field response efficiency of the mobile energy storage system. The invention adopts the following technical scheme. The invention provides an online power-exchanging type mobile energy storage system, which comprises: The system comprises at least 1 group of self-holding batteries and DC/DC converters which are connected in series, a plurality of groups of battery-changing batteries and change-over switches which are connected in series, an energy management unit, an AC/DC converter containing a solid-state switch, an isolation transformer and a DC bu