Novel double-battery direct current charging and discharging device

Abstract

The utility model discloses a novel double-battery direct-current charging and discharging device in the technical field of a secondary direct-current system of a power grid. The novel double-battery direct-current charging and discharging device comprises an AC-DC loop, a storage battery charging and discharging loop, a storage battery pack, a DC-DC loop and a control unit, one side of the storage battery charging and discharging loop is connected with the output side of the AC-DC loop, and the other side is connected with the storage battery pack; the input side of the DC-DC loop is used for receiving the voltage output by the AC-DC loop or the discharging current of the storage battery charging and discharging loop; the control unit is used for collecting current and voltage of the input and output sides of the AC-DC loop and the DC-DC loop and controlling the magnitude of the current and the on-off of the loop; the storage battery charging and discharging circuits and the storage battery packs are further used for collecting current and voltage of the storage battery charging and discharging circuits and controlling the magnitude of the current and on-off of the circuits, and the two storage battery charging and discharging circuits and the two storage battery packs are correspondingly arranged. The novel double-battery direct-current charging and discharging device can be used for carrying out charging and discharging tests on a specific storage battery pack, so that the reliability of a secondary direct-current system is improved, and the maintenance cost is reduced.

Description

Technical Field

[0001] This utility model relates to the field of secondary DC power grid systems, and in particular to a novel dual-battery DC charging and discharging device. Background Technology

[0002] Because direct current (DC) can provide a continuous and stable power supply, and because the secondary power system can remain stable for a certain period of time through battery discharge in the event of AC power failure, the secondary control system in the power grid generally uses DC power supply to ensure the high reliability of the secondary system operation within the station. The secondary DC systems of substations, switching stations, ring main units, etc., in the power grid typically convert AC power within the station into DC power through high-frequency charging modules. This DC power supply powers the secondary equipment within the station and is also connected to battery banks. When the system's AC power is lost due to a fault, the battery banks supply power to the secondary equipment within the station, ensuring the stability and reliability of the power supply to the secondary equipment.

[0003] In the traditional DC system described above, backup power relies on battery banks. Therefore, the operating status of the battery banks is crucial to the reliability of the entire DC system. This is especially true for equipment such as substations and ring main units in the distribution network, which are located almost at the end of the grid. The AC system often cannot meet the requirements for dual power supplies. In the event of an incoming line fault, the AC system within the substation will lose power first, causing the secondary system to rely on batteries for power supply immediately. Therefore, the operating status of the batteries directly determines the reliability of the DC system at this point.

[0004] In distribution networks, switching stations and ring main units suffer from numerous issues due to their large equipment size, harsh operating environment, and insufficient maintenance. Many battery banks have already been damaged during actual operation. In traditional DC systems, battery banks are constantly in a float charge state during normal operation, making it impossible to detect insufficient capacity or damage. Verifying the condition of a battery bank requires a discharge test, but power supply systems require 100% reliability. If AC power is lost during the discharge test, the DC system will collapse, causing a power outage. Therefore, in distribution networks where DC system inspections are difficult, such hidden dangers are almost impossible to detect, significantly impacting the DC reliability of existing switching stations and ring main units.

[0005] Currently, the level of automation in the distribution network is gradually improving, and there are more and more protection, measurement and control, and communication equipment in switchgear and ring main units. In order to ensure the reliable operation of the secondary system of the distribution network, a highly reliable and low-maintenance DC system is urgently needed. Utility Model Content

[0006] This application provides a novel dual-battery DC charging and discharging device, which solves the problems of poor reliability and difficult maintenance of existing power distribution network battery packs, improves the reliability of the secondary DC system, and reduces maintenance costs.

[0007] This application provides a novel dual-battery DC charging and discharging device, including an AC-DC circuit, a battery charging and discharging circuit, a battery pack, a DC-DC circuit, and a control unit;

[0008] The AC-DC circuit receives a wide-range AC current of 50Hz or 60Hz at its input side and outputs a first DC voltage at its output side. The output side of the AC-DC circuit is simultaneously connected to both the battery charging / discharging circuit and the input side of the DC-DC circuit.

[0009] The other side of the battery charging and discharging circuit is connected to the battery pack for charging and discharging the battery pack.

[0010] The input side of the DC-DC circuit is connected to both the battery charging and discharging circuit and the output side of the AC-DC circuit to receive the first DC voltage output by the AC-DC circuit or the discharge current of the battery pack through the battery charging and discharging circuit. The output side of the DC-DC circuit outputs a second DC voltage.

[0011] The control unit is electrically connected to the AC-DC circuit, the battery charging and discharging circuit, and the DC-DC circuit respectively. The control unit is used to collect the current and voltage at the input and output sides of the AC-DC circuit and the DC-DC circuit, and to control the output current of the AC-DC circuit and the DC-DC circuit and the circuit connection and disconnection. The control unit is also used to collect the current and voltage of the battery charging and discharging circuit and to control its current magnitude and the circuit connection and disconnection.

[0012] The battery charging and discharging circuit includes a first battery charging and discharging circuit and a second battery charging and discharging circuit that operate in parallel. The battery pack includes a first battery pack and a second battery pack. The first battery charging and discharging circuit is connected to the first battery pack, and the second battery charging and discharging circuit is connected to the second battery pack.

[0013] Based on the above embodiments, this application can be further improved as follows:

[0014] In one embodiment of this application, the novel dual-battery DC charging and discharging device further includes a step-down silicon chain, wherein the first battery charging and discharging circuit and the second battery charging and discharging circuit are respectively connected to the output side of the AC-DC circuit and the input side of the DC-DC circuit through the step-down silicon chain.

[0015] In one embodiment of this application, the first battery pack and the second battery pack are respectively a series-parallel combination of one or more batteries.

[0016] In one embodiment of this application, the battery is a maintenance-free standard lead-acid battery.

[0017] In one embodiment of this application, the second DC voltage is one or more DC voltages, such as 110V, 220V, or 48V.

[0018] In one embodiment of this application, the AC-DC circuit is a unidirectional conversion circuit, which can only be converted from the input side to the output side, and will be cut off in the reverse conversion.

[0019] In one embodiment of this application, the DC-DC circuit is a unidirectional conversion circuit, which can only be converted from the input side to the output side, and the reverse conversion will be cut off.

[0020] In one embodiment of this application, the control unit has a human-interactive interface for setting parameters and displaying the current and voltage of the AC-DC circuit, the DC-DC circuit, and the battery charging and discharging circuit.

[0021] In one embodiment of this application, the control unit is used to output hard contact alarm signals, including module fault, DC grounding, insufficient battery pack capacity, battery fault, etc.

[0022] One or more technical solutions provided in the embodiments of this application have at least the following technical effects or advantages:

[0023] 1. This novel dual-battery DC charging and discharging device can conduct charging and discharging tests on specific battery packs while ensuring reliable power supply from the secondary system. During the test, the AC input of the target battery pack is reduced, and a step-down silicon chain is used to reduce the voltage of one of the battery packs, causing the target battery pack to enter reverse discharge mode. The control unit monitors the discharge time and load current to determine whether the battery and DC output are operating normally, ensuring that the secondary system can provide reliable power supply. The test is conducted sequentially for each battery pack to complete the charging and discharging test of all battery packs.

[0024] 2. In the event of a fault causing AC power loss, the new dual-battery DC charging and discharging device allows multiple parallel-running battery banks to discharge in reverse to the secondary system via the DC-DC system. Even if one battery bank is damaged, it does not affect the discharge process of the other battery banks, thus ensuring higher power supply reliability of the DC system.

[0025] 3. The battery pack of this new dual-battery DC charging and discharging device is designed to operate in parallel with multiple small battery packs (first battery pack or second battery pack). When a small battery pack fails, only that battery pack needs to be replaced, and the other battery packs do not need to be replaced, which greatly reduces the battery operation and maintenance replacement cost. Attached Figure Description

[0026] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to scale.

[0027] Figure 1 This is a structural block diagram of a novel dual-battery DC charging and discharging device according to an embodiment of this application;

[0028] Among them, 1. AC-DC circuit, 2. Battery charging and discharging circuit, 3. Battery pack, 4. DC-DC circuit, 5. Control unit, and 6. Step-down silicon chain. Detailed Implementation

[0029] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are only for illustrating the present invention and not for limiting the scope of the present invention. After reading the present invention, any modifications of the present invention in various equivalent forms by those skilled in the art will fall within the scope defined by the appended claims.

[0030] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0031] In the description of this utility model, it should be noted that the terms "first," "second," "third," etc., are used only for distinguishing descriptions and should not be construed as indicating or implying relative importance. Unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0032] This application provides a novel dual-battery DC charging and discharging device, which solves the problems of poor reliability and difficult maintenance of existing power distribution network battery packs, improves the reliability of the secondary DC system, and reduces maintenance costs.

[0033] The technical solution in this application is to solve the above problems, and the overall approach is as follows:

[0034] Example:

[0035] like Figure 1As shown, a novel dual-battery DC charging and discharging device includes an AC-DC circuit 1, a battery charging and discharging circuit 2, a battery pack 3, a DC-DC circuit 4, a control unit 5, and a step-down silicon chain 6.

[0036] The input side of AC-DC circuit 1 receives a wide-range AC current of 50 Hz or 60 Hz, and the output side outputs a first DC voltage. The output side of AC-DC circuit 1 is simultaneously connected to one side of battery charging / discharging circuit 2 and the input side of DC-DC circuit 4. The other side of battery charging / discharging circuit 2 is connected to battery pack 3 for charging and discharging battery pack 3. That is, the first DC voltage can charge battery pack 3 through battery charging / discharging circuit 2, and similarly, battery pack 3 can also be discharged through battery charging / discharging circuit 2. The input side of DC-DC circuit 4 is simultaneously connected to one side of battery charging / discharging circuit 2 and the output side of AC-DC circuit 1 to receive the first DC voltage output by AC-DC circuit 1 or the discharge current of battery pack 3 through battery charging / discharging circuit 2. The output side of DC-DC circuit 4 outputs a second DC voltage, which is one or more DC voltages, such as one or more combinations of 110V, 220V, and 48V.

[0037] Control unit 5 is electrically connected to AC-DC circuit 1, battery charging and discharging circuit 2 and DC-DC circuit 4 respectively. Control unit 5 is used to collect the current and voltage on the input and output sides of AC-DC circuit 1 and DC-DC circuit 4, and to control the output current of AC-DC circuit 1 and DC-DC circuit 4 and the circuit connection and disconnection. Control unit 5 is also used to collect the charging and discharging current and voltage of battery pack 3 in battery charging and discharging circuit 2 and to control its current magnitude and the circuit connection and disconnection.

[0038] The battery charging and discharging circuit 2 includes a first battery charging and discharging circuit and a second battery charging and discharging circuit that operate in parallel. The battery pack 3 includes a first battery pack and a second battery pack. The first battery charging and discharging circuit is connected to the first battery pack, and the second battery charging and discharging circuit is connected to the second battery pack. The first battery charging and discharging circuit and the second battery charging and discharging circuit are respectively connected to the output side of the AC-DC circuit 1 and the input side of the DC-DC circuit 4 through the step-down silicon chain 6. Correspondingly, the control unit 5 can collect the current and voltage of the first battery charging and discharging circuit and the second battery charging and discharging circuit and control the current magnitude and circuit on / off.

[0039] Furthermore, the control unit 5 can communicate with the DTU via a serial port or remote signaling.

[0040] Furthermore, the control unit 5 has a human-computer interaction interface, supports parameter setting, and can monitor and display the current and voltage status of AC-DC circuit 1, DC-DC circuit 4, and battery charging and discharging circuit 2, and output faults through remote signaling.

[0041] Furthermore, AC-DC circuit 1 is a unidirectional conversion circuit, which can only be converted from the input side to the output side; the reverse conversion will be cut off.

[0042] Furthermore, DC-DC circuit 4 is a unidirectional conversion circuit, which can only be converted from the input side to the output side; reverse conversion will be cut off.

[0043] The first and second battery packs are each a series combination of one or more batteries. Due to the chemical characteristics of lead-acid batteries, if any single battery in a lead-acid battery pack is damaged, the entire battery pack must be replaced. Existing charging and discharging devices typically use four batteries per group, requiring all batteries to be replaced at once, resulting in high replacement costs when the battery pack is damaged. This new dual-battery DC charging and discharging device uses two or a single battery per group, requiring only the replacement of two or a single battery per replacement, thus reducing maintenance costs.

[0044] Optionally, the CPU used in control unit 5 is an STM32F103RCT6.

[0045] Working principle: The CPU can control the output voltage of the AC-DC output circuit, outputting 27V to charge the battery and outputting 22.4V to activate the battery and discharge the load.

[0046] Battery activation process: First, confirm that both sets of batteries are fully charged. Reduce the AC-DC output voltage to 22.4V. For the unactivated batteries, reduce the voltage to 22.4V using a step-down silicon chain. Activate the batteries by discharging them under a load, calculating the battery capacity and the discharge time.

[0047] The specific implementation process of this novel dual-battery DC charging and discharging device is as follows:

[0048] Suppose that the DC system in a 10kV switchgear of a distribution network is powered by this novel dual-battery DC charging and discharging device, operating as a single unit, and outputting a passive open contact to the DTU. Generally, this DC system has three operating states.

[0049] First, it is in normal operating condition. After the AC input passes through the AC-DC circuit, the output DC voltage supplies power to the secondary system within the substation. Simultaneously, it charges each battery bank through the battery charging and discharging circuit, with each battery bank in a float charge state. Each control unit monitors the status of this device in real time, monitoring and displaying the current and voltage status and grounding conditions of the AC-DC circuit, DC-DC circuit, and battery charging and discharging circuit, and issuing alarms according to set logic. When an external distribution network line fails, because the secondary system within the substation is reliably powered, the relay protection can promptly trip to clear the fault, ensuring the safe operation of the distribution network.

[0050] Secondly, the battery testing state involves conducting charge and discharge tests on each battery bank in this novel dual-battery DC charge and discharge device. When the novel dual-battery DC charge and discharge device reaches the activation cycle, it automatically detects that the activation conditions are met and automatically enters the activation state. Specifically, if the system detects a fault or charging state in another battery bank within the charging and discharging device, the charge and discharge test will not begin until the abnormal operation of the other battery banks disappears. Simultaneously, once the charging and discharging device receives a signal and begins the test, other battery banks will be unable to enter the charge and discharge test state to ensure reliable power supply to the secondary system during the charge and discharge test.

[0051] After the charge / discharge test begins, the AC input to the test battery bank is interrupted. The test battery bank will then discharge instantaneously through the charge / discharge circuit. Simultaneously, the control circuit will detect the discharge current and voltage of the battery bank to comprehensively assess its capacity and status. After activation, based on the activation results, the control unit communicates with the DTU via remote signaling. The DTU reports the activation results to the master station. If the battery is normal or faulty, maintenance personnel check the information received by the master station. If the battery is faulty, the corresponding battery bank is replaced. Throughout the entire test process, the substation's secondary system remains reliably powered, ensuring the reliability of the secondary system while checking the operation of each battery bank.

[0052] Thirdly, in the event of an AC input failure, the battery banks are in a discharging state. When all external AC input is lost, the battery banks in this novel dual-battery DC charging and discharging device discharge through both the battery charging and discharging circuit and the DC-DC circuit, while simultaneously balancing the discharge current to ensure reliable power supply to the secondary system of the switchgear for a certain period. When external AC is restored, the discharging battery banks will enter the charging state. In particular, compared with traditional DC systems, using this novel dual-battery DC charging and discharging device means that if one battery bank fails, it will not affect the power output of the other battery banks, greatly improving the reliability of the DC system.

[0053] Although embodiments of the present invention have been shown and described above, and three field scenarios have been illustrated, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A novel dual-battery DC charging and discharging device, characterized in that, Includes AC-DC circuit, battery charging and discharging circuit, battery pack, DC-DC circuit and control unit; The AC-DC circuit receives AC power at its input side, and the output side of the AC-DC circuit is simultaneously connected to both the battery charging / discharging circuit and the input side of the DC-DC circuit. The other side of the battery charging and discharging circuit is connected to the battery pack for charging and discharging the battery pack. The input side of the DC-DC circuit is connected to both the battery charging / discharging circuit and the output side of the AC-DC circuit, and the output side of the DC-DC circuit outputs a second DC voltage. The control unit is electrically connected to the AC-DC circuit, the battery charging / discharging circuit, and the DC-DC circuit respectively. The control unit is used to collect the current and voltage at the input and output sides of the AC-DC circuit and the DC-DC circuit, and to control the output current of the AC-DC circuit and the DC-DC circuit and the circuit connection / disconnection. The control unit is also used to collect the current and voltage of the battery charging / discharging circuit and to control the battery charging / discharging current and the circuit connection / disconnection. The battery charging and discharging circuit includes a first battery charging and discharging circuit and a second battery charging and discharging circuit operating in parallel. The battery pack includes a first battery pack and a second battery pack. The first battery charging and discharging circuit is connected to the first battery pack, and the second battery charging and discharging circuit is connected to the second battery pack. The novel dual-battery DC charging and discharging device also includes a step-down silicon chain. The first battery charging and discharging circuit and the second battery charging and discharging circuit are respectively connected to the output side of the AC-DC circuit and the input side of the DC-DC circuit through the step-down silicon chain.

2. The novel dual-battery DC charging and discharging device according to claim 1, characterized in that: The first battery pack and the second battery pack are each a series combination of one or more batteries.

3. The novel dual-battery DC charging and discharging device according to claim 2, characterized in that: The battery is a maintenance-free standard lead-acid battery.

4. The novel dual-battery DC charging and discharging device according to claim 1, characterized in that: The second DC voltage is one or more DC voltages.

5. The novel dual-battery DC charging and discharging device according to claim 1, characterized in that: The AC-DC circuit described is a unidirectional conversion circuit, which can only be converted from the input side to the output side; the reverse conversion will be cut off.

6. The novel dual-battery DC charging and discharging device according to claim 1, characterized in that: The DC-DC circuit is a unidirectional conversion circuit, which can only be converted from the input side to the output side; the reverse conversion will be cut off.

7. The novel dual-battery DC charging and discharging device according to claim 1, characterized in that: The control unit has a human-interactive interface for setting parameters and displaying the current and voltage of the AC-DC circuit, the DC-DC circuit, and the battery charging and discharging circuit.

8. The novel dual-battery DC charging and discharging device according to claim 1, characterized in that: The control unit communicates with the DTU via a serial port or remote signaling.

9. The novel dual-battery DC charging and discharging device according to claim 8, characterized in that: The control unit is used to output hard contact alarm signals, including module fault, DC grounding, insufficient battery pack capacity, and battery fault.

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