A maintenance device and control method for an energy storage system based on a microgrid

Abstract

The present invention discloses a maintenance device and control method for a microgrid-based energy storage system. The main energy storage battery group and the backup energy storage battery group of the maintenance device are respectively connected to the DC bus through normally closed contactors with interlocked motion. The main energy storage battery group and the backup energy storage battery group are respectively connected to a common connection point through normally open contactors with interlocked motion. The common connection point is respectively connected to the DC input terminal of a DC-AC grid-connected / off-grid inverter power supply and the output terminal of a DC-DC charging management module through corresponding normally open contactors; the AC output terminal of the DC-AC grid-connected / off-grid inverter power supply is connected to the AC bus, and the input terminal of the DC-DC charging management module is connected to the DC bus; the cathode of a high-power diode is connected to the DC bus, and the anode of the high-power diode is connected to the positive electrode of the main energy storage battery group. The present invention eliminates the need to disconnect the tested battery from the bus for independent nuclear discharge, thus achieving seamless switching of DC system power supply.

Description

Technical Field

[0001] The present invention belongs to the field of renewable energy power generation technology, and relates to a maintenance device and control method for a microgrid-based energy storage system, which is used for charging and discharging maintenance of large-capacity energy storage battery packs in renewable energy power generation systems, and is suitable for charging and discharging maintenance of dedicated energy storage battery packs for renewable energy power generation systems such as wind power generation, solar photovoltaic power generation, and hydropower generation. Background Art

[0002] As one of the few remaining non-renewable energy sources in the world, such as oil and coal, the increasing demand for production activities and the increasing intensity of extraction have led to a sharp decline in the global supply of these non-renewable energy sources. To address this energy crisis, the demand for the development of new energy sources is increasing.

[0003] With the continuous advancement of science and technology, these new energy technologies have been widely applied to power systems. New energy sources are typically generated through natural energy sources such as wind, solar, and hydropower. However, in terms of stability, these power generation methods often exhibit certain fluctuations and intermittent characteristics, making their regulation difficult. This also poses risks to the safety of the power system. To address this issue, various energy storage technologies have emerged. Among numerous energy storage technologies, such as compressed air, pumped storage, and battery storage, battery storage remains the most widely used due to its ease of implementation and rapid deployment, meeting residents' daily electricity needs and the coordination and scheduling of power generation, transmission, and distribution. However, the large number of energy storage battery packs used in battery storage technologies is expensive and has a short service life. Therefore, strengthening the maintenance of energy storage batteries and extending their lifespan is crucial.

[0004] Traditional maintenance methods cannot meet the growing demand for battery maintenance. They require numerous and inconvenient test instruments, require high professional skills from maintenance personnel, lack scientific testing analysis and evaluation, lack effective daily testing methods, lack a comprehensive testing platform, and suffer from low intelligence. Therefore, a technical solution for the charge and discharge maintenance management of energy storage battery packs is needed. Summary of the Invention

[0005] To address the above-mentioned problems, the present invention provides a maintenance device for a microgrid-based energy storage system, comprising a DC-DC charging management module, a DC-AC inverter module, an energy storage battery pack, a circuit breaker, and a contactor. This device eliminates the need to disconnect the tested battery from the busbar for independent nuclear capacity discharge, thereby achieving seamless switching of DC system power supply, reducing the professional skill requirements for maintenance personnel, and solving the problems existing in the prior art.

[0006] Another object of the present invention is to provide a control method for a maintenance device of an energy storage system based on a microgrid.

[0007] The technical solution adopted by the present invention is a maintenance device for an energy storage system based on a microgrid, comprising

[0008] DC bus, used to connect new energy power generation equipment;

[0009] AC bus, used to supply power to the grid or local AC equipment;

[0010] A main energy storage battery group and a backup energy storage battery group, each of which is connected to the DC bus through an interlocked normally closed contactor, and each of which is connected to a common connection point through an interlocked normally open contactor. The common connection point is connected to the DC input terminal of the DC-AC grid-connected / off-grid inverter power supply and the output terminal of the DC-DC charging management module through corresponding normally open contactors; the AC output terminal of the DC-AC grid-connected / off-grid inverter power supply is connected to the AC bus, and the input terminal of the DC-DC charging management module is connected to the DC bus;

[0011] A high-power diode, wherein the cathode of the high-power diode is connected to the DC bus, and the anode of the high-power diode is connected to the positive electrode of the main energy storage battery pack.

[0012] Furthermore, the DC bus is connected to one end of the normally closed contact of the first normally closed DC contactor, and the other end of the normally closed contact of the first normally closed DC contactor is connected to the main energy storage battery pack; the DC bus is connected to one end of the normally closed contact of the second normally closed DC contactor, and the other end of the normally closed contact of the second normally closed DC contactor is connected to the backup energy storage battery pack, and the first normally closed DC contactor and the second normally closed DC contactor are interlocked.

[0013] Furthermore, the DC bus is connected to the input end of the DC-DC charging management module through the normally open contact of the first normally open DC contactor, the output end of the DC-DC charging management module is connected to one end of the normally open contact of the second normally open DC contactor, and the other end of the normally open contact of the second normally open DC contactor is respectively connected to one end of the normally open contacts of the third normally open DC contactor, the fourth normally open DC contactor, and the fifth normally open DC contactor to form a common connection point; the other end of the normally open contact of the third normally open DC contactor is connected to the positive pole of the main energy storage battery pack; the other end of the normally open contact of the fourth normally open DC contactor is connected to the positive pole of the backup energy storage battery pack; the other end of the normally open contact of the fifth normally open DC contactor is connected to the DC input end of the DC-AC grid-connected / off-grid inverter power supply, and the AC output end of the DC-AC grid-connected / off-grid inverter power supply is connected to the AC bus; the third normally open DC contactor and the fourth normally open DC contactor are interlocked.

[0014] Furthermore, an AC circuit breaker is provided between the AC output terminal of the DC-AC grid-connected / off-grid inverter power supply and the AC bus.

[0015] Furthermore, the first normally closed DC contactor, the second normally closed DC contactor, the third normally open DC contactor, the fourth normally open DC contactor, the first normally open DC contactor, the second normally open DC contactor, and the fifth normally open DC contactor are respectively connected to the external control circuit through the eight-bit control interface to realize the switching of each contactor according to the agreed control protocol and control logic.

[0016] Furthermore, one end of the normally closed auxiliary contact of the second normally closed DC contactor is connected to the first control terminal of the eight-bit control interface, and the other end of the normally closed auxiliary contact of the second normally closed DC contactor is connected to one end of the control wire package of the first normally closed DC contactor;

[0017] One end of the normally closed auxiliary contact of the first normally closed DC contactor is connected to the second control terminal of the eight-bit control interface, and the other end of the normally closed auxiliary contact of the first normally closed DC contactor is connected to one end of the control wire package of the second normally closed DC contactor;

[0018] One end of the normally closed auxiliary contact of the fourth normally open DC contactor is connected to the third control terminal of the eight-bit control interface, and the other end of the normally closed auxiliary contact of the fourth normally open DC contactor is connected to one end of the control line package of the third normally open DC contactor;

[0019] One end of the normally closed auxiliary contact of the third normally open DC contactor is connected to the fourth control terminal of the eight-bit control interface, and the other end of the normally closed auxiliary contact of the third normally open DC contactor is connected to one end of the control line package of the fourth normally open DC contactor;

[0020] One end of the control line package of the first normally open DC contactor is connected to the fifth control terminal of the eight-bit control interface;

[0021] One end of the control line package of the second normally open DC contactor is connected to the sixth control terminal of the eight-bit control interface;

[0022] One end of the control line package of the fifth normally open DC contactor is connected to the seventh control terminal of the eight-bit control interface;

[0023] The eighth control terminal of the eight-bit control interface is connected to a common point after the other ends of the control line packages of the first normally closed DC contactor, the second normally closed DC contactor, the third normally open DC contactor, the fourth normally open DC contactor, the first normally open DC contactor, the second normally open DC contactor and the fifth normally open DC contactor are cascaded.

[0024] Furthermore, the power of the high-power diode is determined as 2-3 times the rated current of the system.

[0025] A control method for a maintenance device of an energy storage system based on a microgrid, comprising:

[0026] When the new energy power generation equipment has sufficient power, the normally closed contactors between the main energy storage battery group and the DC bus, and the normally closed contactors between the backup energy storage battery group and the DC bus are controlled to maintain their initial normally closed state; the other contactors are disconnected, and the new energy power generation equipment stores and charges the main energy storage battery group and the backup energy storage battery group normally through the DC bus;

[0027] When discharging and maintaining the main energy storage battery pack, the normally closed contactor between the main energy storage battery pack and the DC bus is disconnected, while the normally open contactors between the main energy storage battery pack and the common connection point, and between the common connection point and the DC-AC grid-connected / off-grid inverter, are closed. The remaining contactors remain in their initial states. The voltage of the main energy storage battery pack is inverted by the DC-AC grid-connected / off-grid inverter and then connected to the AC bus to supply power to the grid or local AC equipment, thus performing discharge maintenance on the main energy storage battery pack.

[0028] When the main energy storage battery pack needs to be charged after discharge maintenance, the normally closed contactor between the main energy storage battery pack and the DC bus is controlled to be disconnected, and the normally open contactor between the main energy storage battery pack and the public connection point, and the normally open contactor between the public connection point and the output end of the DC-DC charging management module are controlled to be attracted, while the other contactors remain in their initial states. The DC bus charges the main energy storage battery pack through the DC-DC charging management module. The backup energy storage battery pack is online and ready to provide external power at any time.

[0029] When discharging and maintaining the backup energy storage battery pack, the normally closed contactor between the backup energy storage battery pack and the DC bus is controlled to be disconnected, and the normally open contactors between the backup energy storage battery pack and the public connection point, and between the public connection point and the DC-AC grid-connected / off-grid inverter power supply, are controlled to be closed. The remaining contactors remain in their initial states. The voltage of the backup energy storage battery pack is inverted by the DC-AC grid-connected / off-grid inverter power supply and then connected to the AC bus to supply power to the grid or local AC equipment, thus performing discharge maintenance on the backup energy storage battery pack.

[0030] When the backup energy storage battery pack needs to be charged after discharge maintenance, the normally closed contactor between the backup energy storage battery pack and the DC bus is controlled to be disconnected, the normally open contactor between the backup energy storage battery pack and the public connection point is controlled to be closed, and the normally open contactor between the public connection point and the output end of the DC-DC charging management module is controlled to be attracted, and the other contactors remain in their initial states unchanged; the DC bus charges the backup energy storage battery pack through the DC-DC charging management module.

[0031] A control method for a maintenance device of an energy storage system based on a microgrid, comprising:

[0032] When the new energy power generation equipment has sufficient power, the first normally closed DC contactor and the second normally closed DC contactor are controlled to maintain their initial normally closed state, and the other contactors are in the disconnected state. The new energy power generation equipment stores and charges the main energy storage battery group and the backup energy storage battery group normally through the DC bus.

[0033] When performing discharge maintenance on the main energy storage battery pack, the first normally closed DC contactor is controlled to open, the normally open contact of the third normally open DC contactor is controlled to close, and the normally open contact of the fifth normally open DC contactor is controlled to close, thereby closing the AC circuit breaker. The contact states of the first normally open DC contactor, the second normally open DC contactor, the fourth normally open DC contactor, and the second normally closed DC contactor remain unchanged. The voltage of the main energy storage battery pack is inverted by the DC-AC grid-connected / off-grid inverter power supply and then connected to the AC bus to supply power to the grid or local AC equipment, thereby performing discharge maintenance on the main energy storage battery pack.

[0034] When the main energy storage battery pack needs to be charged after discharge maintenance, the normally closed contact of the first normally closed DC contactor is controlled to open, the normally open contact of the third normally open DC contactor is controlled to close, the normally open contact of the first normally open DC contactor is controlled to close, and the normally open contact of the second normally open DC contactor is controlled to close. The contacts of the fifth normally open DC contactor are controlled to return to the normally open state, and the AC circuit breaker is controlled to return to the disconnected state. The contacts of the fourth normally open DC contactor and the second normally closed DC contactor are controlled to maintain their initial states. The DC bus charges the main energy storage battery pack through the DC-DC charging management module. The backup energy storage battery pack is online and ready to provide external power at any time.

[0035] When performing discharge maintenance on the backup energy storage battery pack, the normally closed contact of the second normally closed DC contactor is controlled to open, the normally open contact of the fourth normally open DC contactor is controlled to close, and the normally open contact of the fifth normally open DC contactor is controlled to close; the AC circuit breaker is closed; the contact states of the first normally closed DC contactor, the first normally open DC contactor, the second normally open DC contactor, and the third normally open DC contactor remain unchanged; the voltage of the backup energy storage battery pack is inverted by the DC-AC grid-connected / off-grid inverter power supply and then connected to the AC bus to supply power to the grid or local AC equipment, and discharge maintenance is performed on the backup energy storage battery pack;

[0036] When the backup energy storage battery pack needs to be charged after discharge maintenance, the normally closed contact of the second normally closed DC contactor is controlled to be opened, the normally open contact of the fourth normally open DC contactor is controlled to be closed, the normally open contact of the first normally open DC contactor is controlled to be closed, the normally open contact of the second normally open DC contactor is controlled to be closed, the contacts of the fifth normally open DC contactor are controlled to be restored to the normally open state, and the AC circuit breaker is restored to the disconnected state; the contacts of the first normally closed DC contactor and the third normally open DC contactor are controlled to maintain their initial states unchanged; the DC bus charges the backup energy storage battery pack through the DC-DC charging management module.

[0037] The beneficial effects of the present invention are:

[0038] The device of the present invention adopts inverter grid-connected technology for battery discharge, which is green and environmentally friendly;

[0039] The device of the present invention adopts an online capacity discharge method, which eliminates the need to disconnect the tested battery from the busbar for individual capacity discharge. At the same time, the energy storage battery pack can be disconnected from the DC busbar and connected to the discharge circuit. When the busbar voltage is too low or the AC power is lost, the diode can achieve seamless switching of the DC system power supply, making it easy for engineering technicians to implement the energy storage battery pack charge and discharge maintenance management system.

[0040] The device of the present invention has the function of automatically performing program-controlled charging. Without changing the voltage / current output of the rectifier, the float charge voltage and current are automatically adjusted by the DC-DC charging management module according to changes in the external environment, thereby realizing trickle charging. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0042] Figure 1 It is a schematic diagram of the electrical system design principle of an embodiment of the present invention.

[0043] Figure 2 Schematic diagram of the electrical control principle of an embodiment of the present invention.

[0044] Figure 3 This is a schematic diagram of the electrical principle of performing discharge maintenance on a main energy storage battery pack according to an embodiment of the present invention.

[0045] Figure 4 This is a schematic diagram of the electrical principle of an embodiment of the present invention when a main energy storage battery pack needs to be charged after discharge maintenance.

[0046] Figure 5 This is a schematic diagram of the electrical principle when discharging and maintaining the backup energy storage battery pack according to an embodiment of the present invention.

[0047] Figure 6 This is a schematic diagram of the electrical principle of an embodiment of the present invention when the backup energy storage battery pack needs to be charged after discharge maintenance.

[0048] In the figure, 1. DC bus, 2. AC bus, 3. First normally closed DC contactor, 4. High-power diode, 5. First normally open DC contactor, 6. DC-DC charging management module, 7. Second normally open DC contactor, 8. Third normally open DC contactor, 9. Fourth normally open DC contactor, 10. Second normally closed DC contactor, 11. Main energy storage battery pack, 12. Fifth normally open DC contactor, 13. Backup energy storage battery pack, 14. DC-AC grid-connected / off-grid inverter power supply, 15. AC circuit breaker, 16. Eight-bit control interface. DETAILED DESCRIPTION

[0049] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only 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 making creative efforts are within the scope of protection of the present invention.

[0050] Example 1,

[0051] The electrical principle of a maintenance device for an energy storage system based on a microgrid, such as Figure 1 It consists of a DC-DC charging management module 6, a DC-AC inverter module (DC-AC grid-connected / off-grid inverter power supply 14), a main energy storage battery group 11, a backup energy storage battery group 13, and electrical components such as an AC circuit breaker 15 and a contactor.

[0052] The DC bus 1 modulated and rectified by corresponding professional converter equipment for renewable energy power generation such as wind power generation or solar power generation is connected to one end of the normally closed contact of the first normally closed DC contactor 3, and the other end of the normally closed contact of the first normally closed DC contactor 3 is connected to the main energy storage battery pack 11; the cathode of the high-power diode 4 is connected to the DC bus 1, and the anode of the high-power diode 4 is connected to the positive electrode of the main energy storage battery pack 11; the DC bus 1 is connected to one end of the normally closed contact of the second normally closed DC contactor 10, and the other end of the normally closed contact of the second normally closed DC contactor 10 is connected to the backup energy storage battery pack 13.

[0053] The power of the high-power diode 4 is determined to be 2-3 times the rated current of the system to prevent the system current from exceeding the diode's withstand current and causing the diode to burn out. If it is less than 2 times, the high-power diode 4 has insufficient overcurrent redundancy and is prone to burn out. If the value is greater than 3, of course the safety is better, but the cost increases, which is not economical.

[0054] The DC bus 1 is connected to the input end of the DC-DC charging management module 6 through the normally open contact of the first normally open DC contactor 5. The output end of the DC-DC charging management module 6 is connected to one end of the normally open contact of the second normally open DC contactor 7. The other end of the normally open contact of the second normally open DC contactor 7 is respectively connected to one end of the normally open contacts of the third normally open DC contactor 8, the fourth normally open DC contactor 9, and the fifth normally open DC contactor 12 to form a common connection point; the other end of the normally open contact of the third normally open DC contactor 8 is connected to the positive electrode of the main energy storage battery pack 11; the other end of the normally open contact of the fourth normally open DC contactor 9 is connected to the positive electrode of the backup energy storage battery pack 13; the other end of the normally open contact of the fifth normally open DC contactor 12 is connected to the DC input end of the DC-AC grid-connected / off-grid inverter power supply 14, and the AC output end of the DC-AC grid-connected / off-grid inverter power supply 14 is connected to the AC bus 2 via the AC circuit breaker 15.

[0055] The electrical control principle of the large-capacity energy storage battery pack charge and discharge maintenance management technology of the present invention is as follows: Figure 2The first control terminal 16_1 of the eight-bit control interface 16 is connected to one end of the normally closed auxiliary contact 10_2 of the second normally closed DC contactor 10, and the other end of the normally closed auxiliary contact 10_2 of the second normally closed DC contactor 10 is connected to one end of the control line package 3_1 of the first normally closed DC contactor 3; the second control terminal 16_2 of the eight-bit control interface 16 is connected to one end of the normally closed auxiliary contact 3_2 of the first normally closed DC contactor 3, and the other end of the normally closed auxiliary contact 3_2 of the first normally closed DC contactor 3 is connected to one end of the control line package 10_1 of the second normally closed DC contactor 10; the third control terminal 16_3 of the eight-bit control interface 16 is connected to one end of the normally closed auxiliary contact 9_2 of the fourth normally open DC contactor 9, and the other end of the normally closed auxiliary contact 9_2 of the fourth normally open DC contactor 9 is connected to one end of the control line package 8_1 of the third normally open DC contactor 8. end connection; the fourth control terminal 16_4 of the eight-bit control interface 16 is connected to one end of the normally closed auxiliary contact 8_2 of the third normally open DC contactor 8, and the other end of the normally closed auxiliary contact 8_2 of the third normally open DC contactor 8 is connected to one end of the control line package 9_1 of the fourth normally open DC contactor 9; the fifth control terminal 16_5 of the eight-bit control interface 16 is connected to one end of the control line package 5_1 of the first normally open DC contactor 5; the sixth control terminal 16_6 of the eight-bit control interface 16 is connected to one end of the control line package 7_1 of the second normally open DC contactor 7; the seventh control terminal 16_7 of the eight-bit control interface 16 is connected to one end of the control line package 12_1 of the fifth normally open DC contactor 12; the eighth control terminal 16_8 of the eight-bit control interface 16 is connected to the common point after the other ends of the control line packages of the seven DC contactors described above are cascaded. Engineering or R&D design personnel connect to the eight-bit control interface 16 through the intelligent instrument control interface, and can implement remote or local intelligent control operations according to the agreed control protocol and control logic.

[0056] The control method of the embodiment of the present invention:

[0057] In the embodiment of the present invention, when the new energy power generation system operates normally, the DC bus 1 modulated and rectified by the corresponding professional converter equipment transmits power to the power grid through the power generation system's own complete inverter equipment. Figure 1As shown, in the embodiment of the present invention, the first normally closed DC contactor 3 and the second normally closed DC contactor 10 remain in an initial normally closed state, so that the energy storage battery group (including the main energy storage battery group 11 and the backup energy storage battery group 13) are connected in parallel with the DC bus 1, and the energy storage battery group maintains a normal energy storage and charging state. The first normally open DC contactor 5, the second normally open DC contactor 7, the third normally open DC contactor 8, the fourth normally open DC contactor 9, the fifth normally open DC contactor 12, and the AC circuit breaker 15 are all in an initial disconnected state. The DC-DC charging management module 6 and the DC-AC grid-connected / off-grid inverter power supply 14 do not operate and do not consume power.

[0058] When the main energy storage battery pack 11 is discharged for maintenance, Figure 3 As shown, the right side of the figure is an equivalent diagram of the left side of the figure. The first control terminal 16_1 of the eight-bit control interface 16 is controlled by the external control circuit to provide a control voltage, and the control coil 3_1 of the first normally closed DC contactor 3 is energized, causing the normally closed contact of the first normally closed DC contactor 3 to be actuated and opened. The third control terminal 16_3 of the eight-bit control interface 16 is controlled by the control circuit to provide a control voltage, and the control coil 8_1 of the third normally open DC contactor 8 is energized, causing the normally open contact of the third normally open DC contactor 8 to be actuated and closed. The seventh control terminal 16_7 of the eight-bit control interface 16 is controlled by the control circuit to provide a control voltage, and the control coil 12_1 of the fifth normally open DC contactor 12 is energized, causing the normally open contact of the fifth normally open DC contactor 12 to be actuated and closed. The AC circuit breaker 15 is closed. The contact states of the first normally open DC contactor 5, the second normally open DC contactor 7, the fourth normally open DC contactor 9, and the second normally closed DC contactor 10 remain unchanged. At this point, the voltage at the terminals of the main energy storage battery pack 11 is inverted by the DC-AC grid-connected / off-grid inverter 14 into standard grid-connectable AC power, which is then integrated into the AC bus 2 to power the grid or local AC equipment. During this discharge process, various energy storage battery performance parameters, such as the discharge voltage, discharge current, discharge time, cell voltage, cell temperature, and cell internal resistance, of the main energy storage battery pack 11 can be monitored. Computer analysis software is used to analyze the performance of the main energy storage battery pack 11 and provide a maintenance plan. During this process, the new energy power generation system uses the backup energy storage battery pack 13 as an energy storage device. The built-in high-power diode 4 ensures that when the main energy storage battery pack 11 is disconnected from the DC bus 1 and connected to the discharge circuit, it can still seamlessly supply power to the DC bus 1. This ensures that the main energy storage battery pack 11 can immediately participate in external power supply when the renewable energy power generation is insufficient. When the battery pack is required to provide external power, maintenance work on the current battery pack is terminated.

[0059] When the main energy storage battery pack 11 needs to be charged after discharge maintenance, such as Figure 4As shown, the right side of the figure is an equivalent diagram of the left side of the figure. The first control terminal 16_1 of the eight-bit control interface 16 is controlled by the external control circuit to provide a control voltage, and the control line package 3_1 of the first normally closed DC contactor 3 is energized, so that the normally closed contact of the first normally closed DC contactor 3 is actuated and disconnected; the third control terminal 16_3 of the eight-bit control interface 16 is controlled by the control circuit to provide a control voltage, and the control line package 8_1 of the third normally open DC contactor 8 is energized, so that the normally open contact of the third normally open DC contactor 8 is actuated and closed; the fifth control terminal 16_5 of the eight-bit control interface 16 is controlled by the control circuit to provide a control voltage. A control voltage is output, energizing the control coil 5_1 of the first normally open DC contactor 5, causing its normally open contacts to close. The control circuit then controls the sixth control terminal 16_6 of the eight-bit control interface 16 to supply a control voltage, energizing the control coil 7_1 of the second normally open DC contactor 7, causing its normally open contacts to close. This controls the contacts of the fifth normally open DC contactor 12 to return to their normally open state, and the AC circuit breaker 15 to their disconnected state. The contacts of the fourth normally open DC contactor 9 and the second normally closed DC contactor 10 remain in their initial states. At this point, the DC bus 1 charges the main energy storage battery pack 11 via the DC-DC charging management module 6. When the main energy storage battery pack 11 is disconnected from the DC bus 1 for maintenance, the backup energy storage battery pack 13 must remain online and ready to provide power at all times.

[0060] After the main energy storage battery pack 11 is fully charged, it can continue to discharge according to the above-described discharge control process. Alternatively, the first normally closed DC contactor 3 can be controlled to return to a closed state, and the first normally open DC contactor 5, the second normally open DC contactor 7, and the third normally open DC contactor 8 can be disconnected and restored to a normally open state, thereby integrating the main energy storage battery pack 11 into the DC bus 1. This maintains the main energy storage battery pack 11 in a system-online state at all times, allowing the main energy storage battery pack 11 to provide power at any time. After the main energy storage battery pack 11 is fully charged, the first normally closed DC contactor 3 can be controlled to return to a closed state, and the first normally open DC contactor 5, the second normally open DC contactor 7, and the third normally open DC contactor 8 can be disconnected and restored to a normally open state, thereby integrating the main energy storage battery pack 11 into the DC bus 1. This prevents problems such as sparking or a sudden drop in system bus voltage that could affect system stability if the voltage difference between the two is too large. The main energy storage battery group 11 is connected to the DC bus 1. When the new energy generation is insufficient, it can provide external power at any time to avoid power interruption.

[0061] When the standby energy storage battery pack 13 is discharged for maintenance, Figure 5As shown, the right side of the figure is an equivalent diagram of the left side of the figure. The second control terminal 16_2 of the eight-bit control interface 16 is controlled by the external control circuit to provide a control voltage, and the control coil 10_1 of the second normally closed DC contactor 10 is energized, causing the normally closed contact of the second normally closed DC contactor 10 to be actuated and opened. The fourth control terminal 16_4 of the eight-bit control interface 16 is controlled by the control circuit to provide a control voltage, and the control coil 9_1 of the fourth normally open DC contactor 9 is energized, causing the normally open contact of the fourth normally open DC contactor 9 to be actuated and closed. The seventh control terminal 16_7 of the eight-bit control interface 16 is controlled by the control circuit to provide a control voltage, and the control coil 12_1 of the fifth normally open DC contactor 12 is energized, causing the normally open contact of the fifth normally open DC contactor 12 to be actuated and closed. The AC circuit breaker 15 is closed. The contact states of the first normally closed DC contactor 3, the first normally open DC contactor 5, the second normally open DC contactor 7, and the third normally open DC contactor 8 remain unchanged. At this point, the voltage at the backup energy storage battery pack 13 is converted by the DC-AC grid-connected / off-grid inverter 14 into standard grid-connectable AC power, which is then fed into the AC bus 2 to power the grid or local AC equipment. During this discharge process, various battery performance parameters, including discharge voltage, discharge current, discharge time, cell voltage, cell temperature, and cell internal resistance, can be monitored. Using corresponding analysis software, the battery pack's performance can be analyzed and a maintenance plan provided. During this process, the new energy power generation system utilizes the main energy storage battery pack 11 as the energy storage device.

[0062] When the backup energy storage battery pack 13 needs to be charged after being discharged for maintenance, Figure 6As shown, the right side of the figure is an equivalent diagram of the left side of the figure. The second control terminal 16_2 of the eight-bit control interface 16 is controlled by the external control circuit to provide a control voltage, and the control line package 10_1 of the second normally closed DC contactor 10 is energized, so that the normally closed contact of the second normally closed DC contactor 10 is actuated and opened; the fourth control terminal 16_4 of the eight-bit control interface 16 is controlled by the control circuit to provide a control voltage, and the control line package 9_1 of the fourth normally open DC contactor 9 is energized, so that the normally open contact of the fourth normally open DC contactor 9 is actuated and closed; the fifth control terminal 16_ 5 supplies a control voltage, energizing the control coil 5_1 of the first normally open DC contactor 5, causing the normally open contacts of the first normally open DC contactor 5 to close. The control circuit controls the sixth control terminal 16_6 of the eight-bit control interface 16 to supply a control voltage, energizing the control coil 7_1 of the second normally open DC contactor 7, causing the normally open contacts of the second normally open DC contactor 7 to close. The contacts of the fifth normally open DC contactor 12 are restored to the normally open state, and the AC circuit breaker 15 is restored to the disconnected state. The contacts of the first normally closed DC contactor 3 and the third normally open DC contactor 8 remain in their initial states. At this point, the DC bus 1 charges the backup energy storage battery pack 13 via the DC-DC charging management module 6. After the backup energy storage battery pack 13 is fully charged, it can continue to discharge according to the above-mentioned discharge control process. Alternatively, the second normally closed DC contactor 10 can be controlled to return to its initial closed state, and the first normally open DC contactor 5, the second normally open DC contactor 7, and the fourth normally open DC contactor 9 can be disconnected and restored to their normally open states, thereby integrating the backup energy storage battery pack 13 into the DC bus 1. By integrating the backup energy storage battery pack 13 into the DC bus 1 after it is fully charged, problems such as sparks caused by a sudden parallel connection when the voltage difference between the two is too large, or a sudden drop in the system bus voltage affecting system stability, can be avoided. During maintenance of the backup energy storage battery pack 13, the main energy storage battery pack 11 must be online in real time so that it can provide power to the outside at any time when the renewable energy generation is insufficient, thereby avoiding power outages.

[0063] In this embodiment of the present invention, the first normally closed DC contactor 3 and the second normally closed DC contactor 10 are interlocked, and the third normally open DC contactor 8 and the fourth normally open DC contactor 9 are interlocked. The interlocking design principle of the contactors is as follows: when the first normally closed DC contactor 3 is actuated, the normally closed auxiliary contact 3_2 of the first normally closed DC contactor 3 is disconnected, the control line package 10_1 of the second normally closed DC contactor 10 is not energized under any circumstances, and the normally closed contact of the second normally closed DC contactor 10 does not actuate and open; when the second normally closed DC contactor 10 is actuated, the normally closed auxiliary contact 10_2 of the second normally closed DC contactor 10 is disconnected, the control line package 3_1 of the first normally closed DC contactor 3 is not energized under any circumstances, and the normally closed contact of the first normally closed DC contactor 3 does not actuate and open. Similarly, when the third normally-open DC contactor 8 is actuated, the normally-closed auxiliary contact 8_2 of the third normally-open DC contactor 8 is disconnected, the control line package 9_1 of the fourth normally-open DC contactor 9 is not energized, and the normally-open contact of the fourth normally-open DC contactor 9 does not close. When the fourth normally-open DC contactor 9 is actuated, the normally-closed auxiliary contact 9_2 of the fourth normally-open DC contactor 9 is disconnected, the control line package 8_1 of the third normally-open DC contactor 8 is not energized, and the normally-open contact of the third normally-open DC contactor 8 does not close. The interlocking design of the contactor operation ensures that when one energy storage battery pack is discharging / charging for maintenance while the other energy storage battery pack is online, the two energy storage battery packs will not be discharged / charged for maintenance at the same time, thus ensuring the stability of the renewable energy power generation system.

[0064] The DC-DC charging management module 6 adopted in the embodiment of the present invention has the function of intelligently judging the status of the energy storage battery and using the "voltage limiting constant current-constant voltage reduced current-floating charge" method for charging, so as to improve charging efficiency, extend battery life, and ensure system safety; parameters such as charging current, equalization charging voltage, termination current, and float charging voltage can be set, and the cumulative charging capacity can be calculated in real time and uploaded to the analysis software for comprehensive analysis.

[0065] The DC-AC grid-connected / off-grid inverter 14 (DC-AC inverter module) employed in this embodiment of the present invention utilizes DSP digital control technology and high-frequency soft-switching technology, resulting in high efficiency and reliability. The inverter's DC input and AC output are fully electrically isolated, meeting relevant power industry requirements. During operation, it functions as an AC power source, converting DC energy into AC energy according to a set power (current) and feeding it back to the grid. The DC-AC grid-connected / off-grid inverter 14 is a known structure in the art. The DC-DC charging management module 6 can be replaced with a conventional DC-DC step-down power supply (or module), also known in the art.

[0066] The DC-DC charging management module 6 manages the charging of the energy storage battery pack, while the DC-AC grid-connected / off-grid inverter 14 manages the discharge of the energy storage battery pack. When disconnected from the national grid, renewable energy sources such as wind or solar power are modulated and rectified by specialized converters to the DC bus 1. Specifically, wind power is AC power, which is rectified by AC-DC to form stable DC power before being fed into the DC bus 1. Solar power is fluctuating DC power, which is regulated by DC-DC to form stable DC power before being fed into the DC bus 1. The DC-DC charging management module 6 manages the charging of the energy storage battery pack. The local equipment includes a contactor switch and a high-power diode 4, which allow the energy storage battery pack to be disconnected from the DC bus 1 and connected to the discharge circuit, while also enabling seamless power supply to the DC bus 1.

[0067] The above description is only a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention are included in the scope of protection of the present invention.

Claims

1. A control method for a maintenance device of an energy storage system based on a microgrid, characterized in that: The maintenance device of the microgrid-based energy storage system includes: A DC bus (1) for connecting to new energy power generation equipment; AC busbar (2), used to supply power to the grid or local AC equipment; A high-power diode (4), wherein the cathode of the high-power diode (4) is connected to the DC bus (1), and the anode of the high-power diode (4) is connected to the positive electrode of the main energy storage battery pack (11); The DC busbar (1) is connected to one end of the normally closed contact of the first normally closed DC contactor (3), and the other end of the normally closed contact of the first normally closed DC contactor (3) is connected to the main energy storage battery pack (11); the DC busbar (1) is connected to one end of the normally closed contact of the second normally closed DC contactor (10), and the other end of the normally closed contact of the second normally closed DC contactor (10) is connected to the backup energy storage battery pack (13), and the first normally closed DC contactor (3) and the second normally closed DC contactor (10) are interlocked in action; The DC bus (1) is connected to the input end of the DC-DC charging management module (6) through the normally open contact of the first normally open DC contactor (5), the output end of the DC-DC charging management module (6) is connected to one end of the normally open contact of the second normally open DC contactor (7), and the other end of the normally open contact of the second normally open DC contactor (7) is respectively connected to one end of the normally open contact of the third normally open DC contactor (8), the fourth normally open DC contactor (9), and the fifth normally open DC contactor (12), to form a common connection point; the third normally open DC contactor The other end of the normally open contact of the contactor (8) is connected to the positive electrode of the main energy storage battery pack (11); the other end of the normally open contact of the fourth normally open DC contactor (9) is connected to the positive electrode of the backup energy storage battery pack (13); the other end of the normally open contact of the fifth normally open DC contactor (12) is connected to the DC input end of the DC-AC grid-connected / off-grid inverter power supply (14), and the AC output end of the DC-AC grid-connected / off-grid inverter power supply (14) is connected to the AC bus (2); the third normally open DC contactor (8) and the fourth normally open DC contactor (9) are interlocked; An AC circuit breaker (15) is provided between the AC output terminal of the DC-AC grid-connected / off-grid inverter power supply (14) and the AC busbar (2); When the electric energy of the new energy power generation equipment is sufficient, the first normally closed DC contactor (3) and the second normally closed DC contactor (10) are controlled to maintain an initial normally closed state, and the first normally open DC contactor (5), the second normally open DC contactor (7), the third normally open DC contactor (8), the fourth normally open DC contactor (9), the fifth normally open DC contactor (12) and the AC circuit breaker (15) are all in an initial disconnected state; the new energy power generation equipment normally stores and charges the main energy storage battery group (11) and the backup energy storage battery group (13) through the DC bus (1); When discharging and maintaining the main energy storage battery pack (11), the first normally closed DC contactor (3) is controlled to be disconnected, the normally open contact of the third normally open DC contactor (8) is controlled to be operated and closed, the normally open contact of the fifth normally open DC contactor (12) is controlled to be operated and closed, and the AC circuit breaker (15) is closed; the contact states of the first normally open DC contactor (5), the second normally open DC contactor (7), the fourth normally open DC contactor (9), and the second normally closed DC contactor (10) remain unchanged; the voltage of the main energy storage battery pack (11) is inverted by the DC-AC grid-connected / off-grid inverter power supply (14) and then connected to the AC bus (2), supplying power to the grid or local AC equipment, and performing discharge maintenance on the main energy storage battery pack (11); When the main energy storage battery group (11) needs to be charged after discharge maintenance, the first normally closed DC contactor (3) is controlled to operate and disconnect the normally closed contact, the third normally open DC contactor (8) is controlled to operate and close the normally open contact, the first normally open DC contactor (5) is controlled to operate and close the normally open contact, the second normally open DC contactor (7) is controlled to operate and close the normally open contact, the fifth normally open DC contactor (12) is controlled to restore the normally open state, and the AC circuit breaker (15) is controlled to restore the disconnected state; the contacts of the fourth normally open DC contactor (9) and the second normally closed DC contactor (10) are controlled to maintain the initial state unchanged; the DC bus (1) charges the main energy storage battery group (11) through the DC-DC charging management module (6); the backup energy storage battery group (13) is in an online state and is ready to provide power to the outside at any time; When discharging and maintaining the backup energy storage battery pack (13), the normally closed contact of the second normally closed DC contactor (10) is controlled to be opened, the normally open contact of the fourth normally open DC contactor (9) is controlled to be closed, and the normally open contact of the fifth normally open DC contactor (12) is controlled to be closed; the AC circuit breaker (15) is closed; the contact states of the first normally closed DC contactor (3), the first normally open DC contactor (5), the second normally open DC contactor (7), and the third normally open DC contactor (8) are controlled to remain unchanged; the voltage of the backup energy storage battery pack (13) is inverted by the DC-AC grid-connected / off-grid inverter power supply (14) and then connected to the AC bus (2), supplying power to the grid or local AC equipment, and discharging and maintaining the backup energy storage battery pack (13); When the standby energy storage battery group (13) needs to be charged after discharge maintenance, the normally closed contact of the second normally closed DC contactor (10) is controlled to be disconnected, the normally open contact of the fourth normally open DC contactor (9) is controlled to be closed, the normally open contact of the first normally open DC contactor (5) is controlled to be closed, the normally open contact of the second normally open DC contactor (7) is controlled to be closed, the contact of the fifth normally open DC contactor (12) is controlled to be restored to the normally open state, and the AC circuit breaker (15) is controlled to be restored to the disconnected state; the contacts of the first normally closed DC contactor (3) and the third normally open DC contactor (8) are controlled to maintain the initial state unchanged; and the DC bus (1) charges the standby energy storage battery group (13) through the DC-DC charging management module (6).

2. The control method for a maintenance device of a microgrid-based energy storage system according to claim 1, characterized in that: The first normally closed DC contactor (3), the second normally closed DC contactor (10), the third normally open DC contactor (8), the fourth normally open DC contactor (9), the first normally open DC contactor (5), the second normally open DC contactor (7), and the fifth normally open DC contactor (12) are respectively connected to an external control circuit via an eight-bit control interface (16), and the switching of each contactor is realized according to an agreed control protocol and control logic.

3. The control method for a maintenance device of a microgrid-based energy storage system according to claim 1, characterized in that: One end of the normally closed auxiliary contact of the second normally closed DC contactor (10) is connected to the first control terminal of the eight-bit control interface (16), and the other end of the normally closed auxiliary contact of the second normally closed DC contactor (10) is connected to one end of the control line package of the first normally closed DC contactor (3); One end of the normally closed auxiliary contact of the first normally closed DC contactor (3) is connected to the second control terminal of the eight-bit control interface (16), and the other end of the normally closed auxiliary contact of the first normally closed DC contactor (3) is connected to one end of the control line package of the second normally closed DC contactor (10); One end of the normally closed auxiliary contact of the fourth normally open DC contactor (9) is connected to the third control terminal of the eight-bit control interface (16), and the other end of the normally closed auxiliary contact of the fourth normally open DC contactor (9) is connected to one end of the control line package of the third normally open DC contactor (8); One end of the normally closed auxiliary contact of the third normally open DC contactor (8) is connected to the fourth control terminal of the eight-bit control interface (16), and the other end of the normally closed auxiliary contact of the third normally open DC contactor (8) is connected to one end of the control line package of the fourth normally open DC contactor (9); One end of the control line package of the first normally open DC contactor (5) is connected to the fifth control terminal of the eight-bit control interface (16); One end of the control line package of the second normally open DC contactor (7) is connected to the sixth control terminal of the eight-bit control interface (16); One end of the control line package of the fifth normally open DC contactor (12) is connected to the seventh control terminal of the eight-bit control interface (16); The eighth control terminal of the eight-bit control interface (16) is connected to a common point after the other ends of the control line packages of the first normally closed DC contactor (3), the second normally closed DC contactor (10), the third normally open DC contactor (8), the fourth normally open DC contactor (9), the first normally open DC contactor (5), the second normally open DC contactor (7) and the fifth normally open DC contactor (12) are cascaded.

4. The control method for a maintenance device of a microgrid-based energy storage system according to claim 1, characterized in that: The power of the high-power diode (4) is determined to be 2-3 times the rated current of the system.

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