High-efficiency energy storage test system and method based on multiple modes

Abstract

The invention discloses an efficient energy storage test system and method based on multiple modes. Two energy storage converters, two battery cabins and a transformer are included. A power grid connection circuit comprises a breaking switch. The energy management system communicates with the energy storage converter, and controls and switches a power supply mode, a drag test mode and a peak clipping and valley filling mode; the two energy storage converters are dragged oppositely to realize internal energy circulation, so that expensive high-power external load equipment is omitted, the energy utilization rate is improved, and waste is avoided; the system integrates a plurality of modes such as off-grid / grid-connected twin trawling test, electricity supplement and peak load shifting and can be seamlessly switched, so that the test requirements can be met, economic benefits can be brought to factories, and the equipment utilization rate and the investment return can be improved; the grid-connected point is provided with an anti-countercurrent device to prevent reverse power transmission to the power grid, thereby solving the potential safety hazard of grid-connected test and ensuring stable operation of the power grid; a single-cabin single-branch structural design is adopted, the system architecture is clear, the layout is compact, maintenance and expansion are convenient, and the system is suitable for limited deployment space.

Description

TECHNICAL FIELD

[0001] The present application relates to a high-efficiency energy storage test system, in particular to a high-efficiency energy storage test system and method based on multiple modes. BACKGROUND

[0002] With the large-scale grid connection of renewable energy and the rapid development of smart grid, energy storage systems (ESS) play an increasingly important role in smoothing new energy fluctuations, peak shaving and frequency modulation, and enhancing power supply reliability, and gradually become an indispensable part of new power systems. As the core component of the energy storage system, the performance and reliability of the power conversion system (PCS) directly affect the operation effect and safety of the entire system. Therefore, before the PCS and the energy storage system are formally put into operation, they must be fully and effectively tested and verified.

[0003] Currently, there are mainly the following several typical schemes for the testing of energy storage systems, especially large-capacity PCSs in the industry: One is the traditional external load-based testing method. This scheme connects the PCS AC output to high-power resistance load cabinets and other energy-consuming devices to simulate real load working conditions. However, this approach has obvious defects. Not only does it require the purchase of high-priced high-power load devices, but also the initial investment cost is large, and the energy utilization efficiency is low during the test process, and the operation economy is poor.

[0004] Therefore, the second scheme called "counter-towing test" appears. This method uses two PCSs to interconnect the AC side, and uses one PCS to discharge and the other PCS to charge to realize the circulation of electric energy between the two PCSs and the battery. This method reduces the dependence on additional loads and significantly improves the energy utilization efficiency during testing. However, this scheme is mostly suitable for off-grid scenarios and is difficult to carry out testing in grid-connected mode, with large application limitations. At the same time, traditional counter-towing testing also lacks systematic management of battery status and is not easy to coordinate with other operating modes.

[0005] On this basis, the third scheme of introducing an energy management system (EMS) appears, which coordinates and controls the PCS operating state to improve the intelligent level of the testing process. This type of system is mostly limited to off-grid operation and does not solve the reverse flow problem that may occur in grid-connected testing, and the safety protection mechanism is insufficient. In addition, the existing test platform has a single function and is generally only used for factory testing, making it difficult to extend to actual applications such as peak shaving, and the comprehensive utilization efficiency of the equipment is not high, which also limits its economic benefits.

[0006] In summary, existing energy storage testing systems still have significant shortcomings in terms of testing cost, energy utilization rate, operational mode diversity, grid security, and functional integration. The industry urgently needs a high-efficiency energy storage testing system and method that can be compatible with both off-grid and grid-connected parallel testing, integrates safety protection mechanisms, and supports flexible switching between multiple modes to systematically address these pain points. Summary of the Invention

[0007] To address the shortcomings of the aforementioned technologies, this invention provides a high-efficiency energy storage testing system and method based on multiple modes.

[0008] To solve the above technical problems, the technical solution adopted by the present invention is: a high-efficiency energy storage testing system based on multiple modes, comprising: Two energy storage converters connected in parallel; The two battery compartments are connected to the DC side of the two energy storage converters, respectively; The transformer has its low-voltage busbar connected in parallel with the AC side of two energy storage converters, and its high-voltage side is used to connect to the power grid. The power grid connection circuit includes a disconnecting switch installed between the high-voltage side of the transformer and the power grid; The energy management system communicates with two energy storage converters to control their operating modes and charging / discharging states. The energy management system is configured to control switching between multiple operating modes, including the following: Power replenishment mode: disconnection and closing, at least one energy storage converter operates in PQ mode to draw power from the grid to charge the corresponding battery compartment; Counter-drive test mode: Controlling two energy storage converters to charge and discharge each other to simulate energy flow in actual operation; Peak shaving and valley filling mode: During periods of low grid electricity price, control the grid to charge the battery compartment; during periods of high grid electricity price, control the battery compartment to discharge to local loads. It also includes a backflow prevention device, which is installed at the grid connection point between the high-efficiency energy storage test system and the power grid to prevent the high-efficiency energy storage test system from feeding back power to the power grid.

[0009] Furthermore, each battery compartment has a capacity of 5MWh, and the battery compartment and its corresponding energy storage converter constitute a single-compartment single-branch structure.

[0010] Furthermore, the towing test modes include off-grid towing test and grid-connected towing test; During off-grid parallel testing, the disconnect switch between the high-voltage side of the transformer and the power grid is disconnected. One energy storage converter operates in VF mode to discharge, while the other energy storage converter operates in PQ mode to charge, thereby allowing energy to circulate between the two battery compartments. During the grid-connected test, the disconnection switch between the high-voltage side of the transformer and the grid is closed, and both of the two energy storage converters work in the PQ mode, one of which charges and the other of which discharges.

[0011] Further, during the off-grid test, first, one of the energy storage converters works in the VF mode to discharge, and the other works in the PQ mode to charge the corresponding battery compartment. When the battery compartment is fully charged, the energy storage converter working in the PQ mode switches to the VF mode to discharge, and the energy storage converter working in the VF mode switches to the PQ mode to charge the corresponding battery compartment.

[0012] Further, the peak shaving mode is specifically that, during the low valley period of the grid price, the disconnection switch is closed, and both of the two energy storage converters work in the PQ mode and charge the corresponding battery compartments; during the high peak period of the grid price, the disconnection switch is closed, and both of the two energy storage converters work in the PQ mode to supply power to the local load.

[0013] Further, the high-efficiency energy storage test system further comprises a host computer test system in communication with the energy management system for remotely setting the operation mode and power parameters and monitoring the state of the high-efficiency energy storage test system, and the host computer test system also supports the communication protocol of the battery management system.

[0014] Further, the high-efficiency energy storage test system adopts a three-level architecture: a high-voltage input level for receiving 10kV high-voltage alternating current; a conversion level including a transformer and two energy storage converters for realizing AC / DC or DC / AC conversion; a test control level including an energy management system and a host computer test system for realizing automatic test and control of the system.

[0015] A method for a high-efficiency energy storage test system based on multiple modes, the method comprising: controlling the operation mode of the high-efficiency energy storage test system by an energy management system; when the power compensation mode is executed, starting at least one energy storage converter to work in the PQ mode to take power from the grid and charge the battery compartment corresponding to the energy storage converter; when the off-grid test mode is executed, controlling the disconnection switch to be disconnected, and controlling one energy storage converter to work in the VF mode to discharge and the other energy storage converter to work in the PQ mode to charge, so that energy circulates between the two battery compartments; when the grid-connected test mode is executed, controlling the disconnection switch to be closed, and controlling both of the two energy storage converters to work in the PQ mode, and issuing a charging power instruction to one of the energy storage converters and a discharging power instruction to the other energy storage converter; When the peak load shaving mode is executed, the energy storage converter is controlled to take power from the grid to charge the battery cabin during the grid price valley period, and the energy storage converter is controlled to release the battery cabin power to the local load during the grid price peak period.

[0016] Further, the system state and the power flow direction of the grid connection point are monitored in real time by the energy management system. When a potential reverse flow risk is detected in the grid connection mode, the output power of the energy storage converter is adjusted to prevent it. When the power regulation of the energy storage converter cannot prevent reverse flow, the hardware disconnection protection is performed by the reverse flow prevention device.

[0017] A multi-mode based efficient energy storage test system and method, two energy storage converters are connected in parallel to realize internal energy circulation, which saves expensive high-power external load equipment, improves energy utilization efficiency, and avoids energy waste; The system integrates off-grid / grid connection test, power compensation and peak load shaving modes, which can be seamlessly switched, not only meeting the test requirements, but also generating economic benefits for factory peak load shaving, improving equipment utilization and investment return; The grid connection point is provided with a reverse flow prevention device to prevent the system from sending power back to the grid, solve the safety hidden danger of grid connection test, and ensure the safe and stable operation of the grid; The single cabin single branch structure design is adopted, the system architecture is clear, the layout is compact, and the maintenance and expansion are convenient, which is suitable for limited deployment space. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 It is a single line diagram.

[0019] Figure 2 It is a system topology diagram.

[0020] Figure 3 It is an electrical schematic diagram. DETAILED DESCRIPTION

[0021] The application will be further described in detail below in combination with the drawings and specific embodiments.

[0022] Embodiment 1

[0023] This embodiment relates to a multi-mode based efficient energy storage test system, which combines Figures 1-2 It is shown together, comprising: Two parallel connected energy storage converters, for the energy storage converter, the series used in this embodiment is hopePCSHVS, which is a commodity model, so its meaning is not explained; Two battery cabins, respectively connected with the DC side of the two energy storage converters; The transformer has its low-voltage busbar connected in parallel with the AC side of two energy storage converters, and its high-voltage side is used to connect to the power grid. For the transformer, the specifications used in this embodiment are 0.4kV (primary side voltage, i.e., the high-voltage side level can be customized) / 0.69kV. The power grid connection circuit includes a disconnecting switch installed between the high-voltage side of the transformer and the power grid; The energy management system communicates with two energy storage converters to control their operating modes and charging / discharging status.

[0024] Based on the above structure, the energy management system is configured to control the switching between multiple modes, including the following modes: Recharge Mode: At the beginning of testing, if the battery compartment has insufficient power, recharging is required. In recharge mode, the disconnect switch is turned on and off. At this time, the disconnect switch is activated. Figure 1 As shown in the diagram, at least one energy storage converter operates in PQ mode to draw power from the grid to charge the corresponding battery compartment. It should be noted that PQ mode, commonly known as grid-connected mode, is the basic control method for grid-connected equipment. By locking the grid voltage phase, it is possible to independently regulate active power (P) and reactive power (Q). Specifically, when one of the battery compartments needs to be recharged, the operator controls QF1 to close remotely or locally. Then, the energy management system or local operation is used to start the corresponding energy storage converter for that battery compartment, set it to operate in PQ mode, and normally set the charging power. The energy storage converter then draws power from the grid at the set power to charge the corresponding battery compartment.

[0025] Parallel-to-parallel test mode: Controlling two energy storage converters to charge and discharge each other, simulating energy flow in actual operation; preferably, the parallel-to-parallel test mode includes off-grid parallel-to-parallel test and grid-connected parallel-to-parallel test: During the off-grid test, the disconnect switch between the high-voltage side of the transformer and the grid is disconnected. One energy storage converter operates in VF mode to discharge, and the other energy storage converter operates in PQ mode to charge, thereby allowing energy to circulate between the two battery compartments. It should be noted that VF mode, commonly known as off-grid mode, actively generates a stable voltage and frequency to supply power to the load. Specifically, after the power compensation is completed, the QF1 is controlled to be turned off, one of the energy storage converters is set to be in the VF mode for discharging, the other energy storage converter is set to be in the PQ mode for charging, and the charging power is given; at this time, the energy storage converter in the PQ mode operates at the set power to charge the corresponding battery cabin, and the energy flows from the battery cabin corresponding to the energy storage converter in the VF mode to the battery cabin until the battery cabin is fully charged; then, the energy storage converter originally operating in the PQ mode is switched to operate in the VF mode for discharging, and the energy storage converter originally operating in the VF mode is switched to operate in the PQ mode for charging the corresponding battery cabin, thereby completing one charging and discharging cycle; it should be noted that the above operation can be repeated multiple times if inter-cabin charging and discharging cycles are required.

[0026] During the grid-to-drag test, the QF1 is controlled to be turned on, the energy management system is used to set both of the energy storage converters to operate in the PQ mode, and the power instructions for charging and discharging are given, so that one grid-to-drag test can be completed; it should be noted that in this mode, the grid-to-drag test can be performed while the power is compensated from the grid.

[0027] Peak shaving and valley filling mode: when the battery cabin is idle, this mode can be run to help the factory save electricity bills, and the basic operation logic is to control the grid to charge the battery cabin during the low valley period of the grid electricity price, and control the battery cabin to discharge to the local load during the peak period of the grid electricity price; Specifically, during the low valley period of the electricity price, the QF1 is controlled to be turned on, and both of the energy storage converters operate in the PQ mode to take power from the grid to charge the corresponding battery cabin; during the peak period of the electricity price, the QF1 is controlled to be turned on, and both of the energy storage converters and the battery cabin operate in the discharging mode of the PQ under the control of the energy management system to output power to the factory load.

[0028] The embodiment also includes an anti-backflow device arranged at the grid connection point of the high-efficiency energy storage test system and the grid, which is used to prevent the high-efficiency energy storage test system from sending power back to the grid and ensure the safety of the grid.

[0029] In the embodiment, the capacity of each battery cabin is 5 MWh, and the battery cabin and the corresponding energy storage converter form a single-cabin single-branch structure, thereby effectively reducing the coupling degree between systems and improving the independence and controllability of the test; it should be noted that the structure with a capacity of 5 MWh and a single-cabin single-branch structure refers to an independent cabin with a capacity of 5 megawatt hours (MWh) in the energy storage system, which has a single power branch.

[0030] The upper computer test system is also included, which is in communication connection with the energy management system for remotely setting the operation mode and power parameters and monitoring the state of the high-efficiency energy storage test system, and supports the communication protocol of the battery management system.

[0031] Reference Figure 2As shown, during commissioning, the platform includes a 10kV switchgear, isolation transformer, energy storage converter, power analyzer, host computer (including host computer testing system), and cable trays inside the equipment. The energy storage converter has a reserved network port for data interaction with an external energy management system, enabling data control during the testing process and remote data viewing. The host computer supports the communication protocols of the secondary and tertiary battery management systems through software.

[0032] like Figure 3 As shown, the electrical system uses a 10kV incoming line for voltage monitoring and protection via a voltage transformer cabinet. The voltage is stepped down to a non-standard 600V low-voltage output via a 10 / 0.6kV transformer (capacity 3450kVA). The voltage transformer cabinet converts the 10.5kV high voltage to 100V / 57.7V low voltage for measurement, insulation monitoring, and relay protection. The voltage is then directed to the converter, where grid power is supplied via the AC side circuit breaker of the energy storage converter. The AC / DC bidirectional operation is achieved through a dual-channel (A / B) AC side architecture (including Hall sensor monitoring points). Energy is then distributed on the DC side through a dual-channel cable path (DC1+ / DC1, DC2+ / DC2- connect to the cable management cabinet, standardized wiring).

[0033] The high-efficiency energy storage test system in this embodiment adopts a three-level architecture: High-voltage input stage, used to receive 10kV high-voltage AC power; The converter stage, including a transformer and two energy storage converters, is used to achieve AC / DC or DC / AC conversion; The test control level, including the energy management system and the host computer test system, is used to realize the automatic testing and control of the system.

[0034] Example 2

[0035] This embodiment is a method based on a multi-mode high-efficiency energy storage testing system, which includes: The operation mode of the high-efficiency energy storage test system is controlled through the energy management system; When the power replenishment mode is executed, at least one energy storage converter is started to operate in PQ mode to draw power from the grid and to charge the battery compartment corresponding to the energy storage converter. When the off-grid against-pull test mode is executed, the control break switch is opened, and one energy storage converter is controlled to work in the VF mode to discharge, and the other energy storage converter is controlled to work in the PQ mode to charge, so that the energy circulates between the two battery compartments; when the grid-connected against-pull test mode is executed, the control break switch is closed, and both of the energy storage converters are controlled to work in the PQ mode, and the charging power instruction is issued to one of the energy storage converters, and the discharging power instruction is issued to the other energy storage converter; When the peak shaving and valley filling mode is executed, the energy storage converter is controlled to take power from the power grid to charge the battery compartment in the power grid price valley period, and the energy storage converter is controlled to release the battery compartment energy to the local load in the power grid price peak period.

[0036] Preferably, the system state and the power flow direction of the grid-connected point are monitored in real time by the energy management system. When the potential reverse flow risk is detected in the grid-connected mode, the output power of the energy storage converter is adjusted to prevent it; When the power regulation of the energy storage converter cannot prevent the reverse flow, the hardware break protection is executed by the anti-reverse flow device.

[0037] The application discloses a high-efficiency energy storage test system and method based on multiple modes. Two energy storage converters are against-pulled to realize internal energy circulation, expensive high-power external load equipment is saved, energy utilization efficiency is improved, and energy waste is avoided. The system integrates off-grid / grid-connected against-pull test, power compensation and peak shaving and valley filling multiple modes, can be seamlessly switched, can meet test requirements, can generate economic benefits for factories by peak shaving and valley filling, and can improve equipment utilization and investment return. An anti-reverse flow device is arranged at the grid-connected point to prevent the system from sending power back to the power grid, solve the safety hidden danger of grid-connected test, and ensure the safe and stable operation of the power grid. A single-compartment single-branch structure design is adopted, the system architecture is clear, the layout is compact, maintenance and expansion are facilitated, and the system is suitable for limited deployment space.

[0038] The above-mentioned embodiments are not a limitation of the application, and the application is not limited to the above examples. Changes, modifications, additions or replacements made by those skilled in the art within the technical solution range of the application are also within the protection scope of the application.

Claims

1. A multi-mode based high efficiency energy storage test system, characterized in that, The high-efficiency energy storage test system comprises: two parallel energy storage converters; two battery compartments connected with the DC sides of the two energy storage converters respectively; a transformer, the low-voltage side bus of which is connected in parallel with the AC sides of the two energy storage converters, and the high-voltage side of which is used for connecting with the power grid; a power grid connection circuit comprising a disconnection switch arranged between the high-voltage side of the transformer and the power grid; an energy management system in communication connection with the two energy storage converters, used for controlling the operation mode and the charging and discharging state of the energy storage converters; the energy management system is arranged to control multiple mode switching operations and comprises the following modes: power compensation mode: the disconnection switch is closed, and at least one of the energy storage converters works in the PQ mode to take power from the power grid to charge the corresponding battery compartment; drag test mode: the two energy storage converters are controlled to charge and discharge with each other to simulate the energy flow in actual operation; peak load shifting mode: the power grid is controlled to charge the battery compartments in the low price period of the power grid, and the battery compartments are controlled to discharge to the local load in the peak period of the power grid; further comprising an anti-backflow device arranged at the grid-connected point of the high-efficiency energy storage test system and the power grid, used for preventing the high-efficiency energy storage test system from sending power back to the power grid.

2. The multi-mode based high efficiency energy storage test system of claim 1, wherein: The capacity of each battery compartment is 5MWh, and the battery compartment and the corresponding energy storage converter constitute a single-compartment single-branch structure.

3. The multi-mode based high efficiency energy storage test system of claim 1, wherein: The drag test mode comprises off-grid drag test and grid-connected drag test; in the off-grid drag test, the disconnection switch between the high-voltage side of the transformer and the power grid is disconnected, one of the energy storage converters works in the VF mode to discharge, and the other energy storage converter works in the PQ mode to charge, so that the energy circulates between the two battery compartments; in the grid-connected drag test, the disconnection switch between the high-voltage side of the transformer and the power grid is closed, and the two energy storage converters both work in the PQ mode, one of the energy storage converters charges, and the other energy storage converter discharges.

4. The multi-mode based high efficiency energy storage test system of claim 3, wherein: in the off-grid drag test, first, one of the energy storage converters is controlled to work in the VF mode to discharge, and the other energy storage converter is controlled to work in the PQ mode to charge the corresponding battery compartment, after the battery compartment is fully charged, the energy storage converter originally working in the PQ mode is switched to work in the VF mode to discharge, and the energy storage converter originally working in the VF mode is switched to work in the PQ mode to charge the corresponding battery compartment.

5. The multi-mode based high efficiency energy storage test system of claim 1, wherein: in the peak load shifting mode, in the low price period of the power grid, the disconnection switch is closed, the two energy storage converters both work in the PQ mode and charge the corresponding battery compartments respectively; in the peak period of the power grid, the disconnection switch is closed, the two energy storage converters both work in the PQ mode to supply power to the local load.

6. The multi-mode based high efficiency energy storage test system of claim 1, wherein: further comprising an upper computer test system in communication connection with the energy management system for remotely setting the operation mode, power parameters and monitoring the state of the high-efficiency energy storage test system, and the upper computer test system also supports the communication protocol of the battery management system.

7. The multi-mode based high efficiency energy storage test system of claim 6, wherein, The high-efficiency energy storage test system adopts a three-level architecture: high-voltage input level, used for receiving 10kV high-voltage alternating current; converter level, comprising the transformer and the two energy storage converters, used for realizing AC / DC or DC / AC conversion; A test control level including the energy management system and the host computer test system is used to realize automatic test and control of the system.

8. The method for multi-mode based high efficiency energy storage test system of claim 1, wherein: The method comprises: Controlling the operation mode of the high-efficiency energy storage test system through the energy management system; When the power compensation mode is executed, at least one energy storage converter is started to work in the PQ mode to take power from the power grid and charge the battery compartment corresponding to the energy storage converter; When the off-grid and drag test mode is executed, the disconnection switch is controlled to be disconnected, one energy storage converter is controlled to work in the VF mode to discharge, and the other energy storage converter is controlled to work in the PQ mode to charge, so that energy circulates between the two battery compartments; when the grid-connected and drag test mode is executed, the disconnection switch is controlled to be connected, and both energy storage converters are controlled to work in the PQ mode, and a charging power instruction is issued to one energy storage converter and a discharging power instruction is issued to the other energy storage converter; When the peak shaving and valley filling mode is executed, the energy storage converter is controlled to take power from the power grid to charge the battery compartment during the valley period of the power grid price, and the energy storage converter is controlled to release the battery compartment energy to the local load during the peak period of the power grid price.

9. The high-efficiency energy storage test system and method based on multiple modes according to claim 8, characterized in that: The energy management system is used to monitor the system state and the power flow direction of the grid-connected point in real time; When potential reverse flow risk is detected in the grid-connected mode, the output power of the energy storage converter is adjusted to prevent it; When the power adjustment of the energy storage converter cannot prevent reverse flow, the hardware disconnection protection is executed through the anti-reverse flow device.

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