Series-parallel storage integrated high-voltage architecture of base station and control method thereof

Abstract

The invention relates to the technical field of electric power, in particular to a base station series-parallel storage integrated high-voltage architecture and a control method thereof. The problems of insufficient standby power and high machine room cost in the prior art are solved. The system comprises an AC / DC converter. A bidirectional DC / DC converter; a standby battery unit; and the direct current bus is connected with the alternating current input end through the AC / DC converter and is connected with the standby battery unit through the bidirectional DC / DC converter. According to the invention, the standby battery unit can be conveniently and independently replaced when a modular fault occurs, and storage integration can be realized; the standby power redundancy is met; the three-hour demand of an operator for power preparation is met, and the power preparation cost can be greatly reduced by using the peak-valley price difference of the electricity price.

Description

Technical Field

[0001] The present invention relates to the field of power technology, and particularly to a high-voltage architecture integrating series and parallel reserves for base stations and a control method therefor. Background Art

[0002] With the rapid deployment of 5G base stations, the capacity of the existing backup battery units of base stations has been difficult to meet the backup power demand of operators for 3 hours. The current solution is to carry out capacity expansion and transformation. The capacity expansion plan is to newly add a battery pack in parallel on the basis of the existing backup battery unit. However, this plan has significant technical challenges: due to possible batch differences and different service life of the parallel battery packs, current backflow is likely to occur during the charging and discharging process, resulting in local temperature rise inside the battery pack. This uneven heating will not only increase the risk of battery thermal runaway, but also may significantly shorten the service life of the overall battery system.

[0003] In the context of the large-scale deployment of 5G networks, the cost structure of base station operations has changed significantly. Among them, the electricity cost has climbed to 30%-40% of the total operating cost, becoming the main cost burden for operators.

[0004] There is an urgent need for a new backup power method to solve the above problems. Summary of the Invention

[0005] A high-voltage architecture integrating series and parallel reserves for base stations and a control method therefor proposed by the present invention solve the problem of high backup power cost in the prior art.

[0006] The technical solution of the present invention is implemented as follows: A high-voltage architecture integrating series and parallel reserves for base stations includes a DC bus connected to a load and a backup battery unit, and further includes an AC / DC converter; a bidirectional DC / DC converter; a battery pack M2 with the same power as the battery pack M1; the battery pack M1 and the battery pack M2 are respectively connected in parallel through a power switch to form a backup battery unit; the DC bus is connected to an AC input terminal through the AC / DC converter and is connected to the backup battery unit through the bidirectional DC / DC converter.

[0007] In a further technical solution, the DC output terminal of the AC / DC converter is directly connected to the bidirectional DC / DC converter and is connected to the load through a power switch; the battery terminal of the bidirectional DC / DC converter is directly connected to the backup battery unit.

[0008] Further technical solution: The backup battery unit further includes a BMS control board and a battery pack. The battery pack is composed of battery modules, and each battery module includes a sampling module, a communication module, and a battery cell module. The sampling module is connected to the BMS control board through the communication module. The two sampling modules perform data transmission through the daisy chain communication method. After the communication modules of the two battery modules are connected in series through a communication line, they are connected to the BMS control board.

[0009] Preferred technical solution of the backup battery unit: The BMS control board controls the output of the AC / DC converter, and the output power is adjusted in real time according to the power consumed by the load and the required power of the backup battery unit. The output current value changes according to the real-time output power.

[0010] Preferred technical solution: When the backup battery unit discharges, the DC voltage output by the backup battery unit through the bidirectional DC / DC converter is higher than the DC voltage at the load end.

[0011] A control method for series-parallel integrated backup of a base station includes the following steps: Step 1: Add a battery pack M2 with the same power as the battery pack M1, and connect them in parallel through a power switch respectively to form a backup battery unit. The sampling module in the backup battery unit collects the current, voltage, and temperature information of the battery cell module and is connected to the BMS control board through the communication module. The DC bus is connected to the AC input terminal through the AC / DC converter and is connected to the backup battery unit through the bidirectional DC / DC converter. The DC power at the load end of the AC / DC converter is connected to the bidirectional DC / DC converter and is connected to the load through a power switch. The DC power at the battery end of the bidirectional DC / DC converter is connected to the backup battery unit. Step 2: The 220V alternating current is converted into DC power at the load end through the AC / DC converter, and the DC power at the load end supplies power to the load. Step 3: The DC power at the load end is converted into DC power at the battery end through the bidirectional DC / DC converter to charge the backup battery unit.

[0012] Further technical solution: When the 220V alternating current is converted into DC power at the load end through the AC / DC converter and the DC power supplies power to the load, specifically: during the peak stage of the electricity price, the BMS control board adjusts the output voltage of the AC / DC converter to the secondary under-voltage + 1V, and the output voltage of the bidirectional DC / DC converter to the secondary under-voltage + 3V. When the battery level of battery pack M1 or battery pack M2 is low and the output voltage cannot be stabilized at the secondary power-off voltage + 3V, the BMS control board adjusts the output voltage of the bidirectional DC / DC converter to the secondary power-off voltage + 1.2V; the battery pack continues to discharge until the output voltage of the bidirectional DC / DC converter is lower than the output voltage of the AC / DC converter, and then the AC / DC converter supplies power to the load; at this time, the BMS control board disconnects the relay switch of the discharged cut-off battery pack and closes the relay switch of the other battery pack, and at the same time adjusts the output voltage of the AC / DC converter to the floating charge voltage.

[0013] In a further technical solution, the conversion of the direct current at the load end to the direct current at the battery end through the bidirectional DC / DC converter to charge the backup battery unit is specifically as follows: the output of the AC / DC converter is controlled by the BMS control board, and the output power is adjusted in real time according to the power consumed by the load and the required power of the backup battery unit; the output current value changes according to the real-time output power. The charging of the backup battery unit can be selected to be carried out during the valley stage of the electricity price.

[0014] A high-voltage architecture for series-parallel reserve integration of base stations and its control method disclosed by the present invention has the following beneficial effects: The backup battery unit is modularized: both battery pack M1 and battery pack M2 are composed of standardized battery packs and standardized interfaces, which is convenient for individual replacement in case of failure.

[0015] Backup redundancy: both battery pack M1 and battery pack M2 can independently supply power for 3 hours. When battery pack M1 fails, battery pack M2 can supply power independently while battery pack M1 is being repaired.

[0016] Reduction of backup cost: The two battery packs are connected in parallel to the DC bus through relay switches and controlled by a single BMS control board, which can realize peak-valley arbitrage using the electricity price difference and reduce the electricity cost of the base station; during the peak electricity price period, battery pack M1 or battery pack M2 supplies power to the load equipment until the discharge cut-off condition of the battery pack is reached; during the valley electricity price period, the battery pack M1 or battery pack M2 is charged through the bidirectional DC / DC converter; it can meet the backup requirement of 3 hours for the operator and also reduce the backup cost using the peak-valley price difference of the electricity price. Description of the Drawings

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0018] Figure 1 : Schematic diagram of the power supply architecture of the present invention; Figure 2 : Circuit schematic diagram of the backup battery unit; Figure 3 : Frame schematic diagram of the backup battery unit. Detailed implementation manners

[0019] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention. Detailed implementation manner one As Figure 1 shown in the schematic diagram of the power supply architecture of the present invention, a high-voltage architecture for series-parallel reserve integration of base stations disclosed by the present invention includes a DC bus connected to a load and a backup battery unit. The load includes important equipment and secondary equipment; the important equipment includes an antenna, an RRU, and a BBU; the secondary equipment includes a monitoring module and a protection module; it also includes an AC / DC converter; a bidirectional DC / DC converter; a battery pack M2 with the same power as the current base station backup battery unit group M1; which is beneficial to the transformation and utilization of the current base station backup battery unit; the battery pack M1 and the battery pack M2 are respectively connected in parallel through a power switch to form a backup battery unit; the DC bus is connected to the AC input end through the AC / DC converter and is connected to the backup battery unit through the bidirectional DC / DC converter. When the commercial power supplies normally, 220V alternating current is converted into direct current at the load end through the AC / DC converter, and the direct current supplies power to the load. At the same time, the direct current at the load end is converted into direct current at the battery end through the bidirectional DC / DC converter to charge the backup battery unit; when the commercial power fails or the output of the AC / DC converter is actively turned off, the backup battery unit supplies power to the load through the bidirectional DC / DC converter.

[0021] While meeting the backup duration requirements of 5G base stations, it can provide fault redundancy. When the battery pack M1 fails, the power switch K1 is controlled to disconnect and the switch power supply K2 is controlled to close by the BMS control board, so that the battery pack M1 is not connected to the circuit and the battery pack M2 is connected to the circuit. When the battery pack M2 fails, the power switch K1 is controlled to close and the power switch K2 is controlled to disconnect by the BMS control board, so that the battery pack M1 is connected to the circuit and the battery pack M2 is not connected to the circuit. When the battery pack M1 or the battery pack M2 fails, the battery pack can be replaced and repaired. Detailed implementation manner two On the basis of the first specific implementation manner, the DC side of the load end of the AC / DC converter is directly connected to the bidirectional DC / DC converter and connected to the load through a power switch; the battery side of the bidirectional DC / DC converter is directly connected to the backup battery unit. When a fault occurs in the load, the power supply to the load is controlled to be turned on and off, so as to realize the start-stop control of the load and ensure the safety of equipment and personnel; for some secondary equipment, according to actual needs, it can be powered on or off at an appropriate time through the power switch to achieve energy saving.

[0023] The BMS control board in the backup battery unit controls the on and off of the battery pack through a power switch. The battery modules in the battery pack collect the cell information of the cell modules through a sampling module, and the sampling module transmits data through a daisy chain communication method; the communication modules of the battery modules are connected in series through communication lines and then connected to the BMS control board.

[0024] As Figure 2 As shown in the circuit schematic diagram of the backup battery unit, the battery pack M1 and the battery pack M2 perform alternating cyclic discharges during the peak electricity price period. During the peak electricity price stage, the BMS control board adjusts the output voltage of the AC / DC converter to the secondary power-off voltage +1V, and the output voltage of the bidirectional DC / DC converter to the secondary power-off voltage +3V; when the battery pack M1 or the battery pack M2 has a low power level and the output voltage cannot be stabilized at the secondary power-off voltage +3V, the output voltage of the bidirectional DC / DC converter is adjusted to the secondary power-off voltage +1.2V; the battery pack continues to discharge until the output voltage of the bidirectional DC / DC converter is lower than the output voltage of the AC / DC converter, and then the AC / DC converter supplies power to the load. At this time, the BMS control board disconnects the relay switch of the discharged cut-off battery pack and closes the relay switch of the other battery pack, and at the same time adjusts the output voltage of the AC / DC converter to the floating charge voltage.

[0025] When the backup battery unit discharges, the DC voltage output by the backup battery unit through the bidirectional DC / DC converter is higher than the DC voltage at the load end. The advantage is that when the battery pack M1 or the battery pack M2 supplies power to the load through the bidirectional DC / DC converter, the battery terminal current is 1 / 2 of the load terminal current, and smaller-sized products can be selected for the electronic components in the battery Pack, saving hardware costs. When the backup battery unit is in the standby state, the DC voltage output by the backup battery unit through the bidirectional DC / DC converter is lower than the DC voltage at the load end.

[0026] Realize the precise control of the backup battery unit and make full use of the power of the battery pack. Specific implementation manner three Based on the above embodiments, the battery pack is charged by a bidirectional DC / DC converter, and the output of the AC / DC converter is controlled by the BMS control board. The output power is adjusted in real time according to the power consumed by the load and the required power of the backup battery unit. The output current value changes according to the real-time output power, and the maximum current value that the line can pass through is determined by looking up the table of the current value that the AC / DC converter can output, the maximum current value of the cable, and the cell charging circuit. The output current value of the AC / DC converter is controlled by the BMS control board to be Min (the cell charging lookup value + the load consumption, the maximum current carrying capacity of the cable, the maximum output current of the AC / DC converter), and then the battery pack is charged after boosting through the bidirectional DC / DC converter.

[0028] During the peak period of electricity price, the load device is powered by the battery pack M1 or the battery pack M2 until the discharge cut-off condition of the battery pack is reached; during the valley period of electricity price, the battery pack M1 or the battery pack M2 is charged through the bidirectional DC / DC converter. This strategy can not only meet the operator's requirement for 3 hours of backup power, but also reduce the backup power cost by using the peak-valley price difference of electricity. Taking a single battery module of 5 KWh as an example, and the battery pack M1 is composed of 2 battery modules. According to the peak-valley price difference in Sichuan Province of about 0.7 yuan, 10 KWh of arbitrage can be carried out every day, about 7 yuan. Specific Embodiment Four: As Figure 3 As shown in the frame schematic diagram of the backup battery unit, the backup battery unit can also adopt 1 BMS control board connected to 2 battery packs; each battery pack is composed of 2 battery modules connected in series; each battery module has a standard communication interface with a sampling module, and the communication interfaces of the 2 battery modules of each battery pack are connected in series and then connected to the BMS control board. The BMS control board identifies the information of each battery module through the physical address; greatly saving the usage amount of the BMS control board and the collaborative work link; while meeting the backup power duration requirement of the 5G base station, sufficient backup power and fault redundancy can be provided. When one of the battery modules fails, the power switch of the battery pack where the battery module is located is controlled by the BMS control board to be disconnected and the power switch of the other battery pack is closed, so that the battery pack where the faulty battery module is located is not connected to the circuit, and the battery module in the faulty battery pack can be replaced and repaired. Specific Embodiment Five: A control method for series-parallel reserve integration of a base station includes the following steps: Step 1: Supplement a battery pack M2 with the same power as the current backup battery unit pack M1 of the base station, and connect them in parallel through a power switch respectively to form a backup battery unit; the sampling module in the backup battery unit collects the current, voltage and temperature information of the battery cell module, and connects to the BMS control board through the communication module; the two sampling modules perform data transmission through the daisy chain communication method; the communication modules of the two battery modules are connected in series through a communication line and then connected to the BMS control board; the BMS control board identifies the battery pack M1, battery pack M2 and their corresponding battery module and battery cell information through the address; the DC bus is connected to the AC input end through an AC / DC converter, and is connected to the backup battery unit through a bidirectional DC / DC converter; the DC power at the load end of the AC / DC converter is connected to the bidirectional DC / DC converter, and is connected to the load through a power switch; the DC power at the battery end of the bidirectional DC / DC converter is connected to the backup battery unit; Step 2: The 220V alternating current is converted into DC power at the load end through the AC / DC converter, and the DC power at the load end supplies power to the load; the DC power at the backup battery unit end is connected to the backup battery unit through a power switch: during the peak electricity price period, the battery unit supplies power to the load, and the BMS control board adjusts the output voltage of the AC / DC converter to the secondary under-voltage +1V, and the output voltage of the bidirectional DC / DC converter to the secondary under-voltage +3V; when the power of battery pack M1 or battery pack M2 is low and the output voltage cannot be stabilized at the secondary under-voltage +3V, the BMS control board adjusts the output voltage of the AC / DC converter to the secondary under-voltage +1.2V; the battery pack continues to discharge until the output voltage of the bidirectional DC / DC converter is lower than the output voltage of the AC / DC converter, and then the AC / DC converter supplies power to the load; at this time, the BMS control board disconnects the relay switch of the discharged cut-off battery pack, closes the relay switch of the other battery pack, and at the same time adjusts the output voltage of the AC / DC converter to the floating charge voltage. The battery pack M1 and the battery pack M2 perform alternating cyclic discharge during the peak electricity price period; Step 3: The DC power at the load end is converted into DC power at the battery end through the bidirectional DC / DC converter to charge the backup battery unit. The BMS control board adjusts the output current of the AC / DC converter according to the charging demand current of the battery, the maximum current that the cable can withstand, and the maximum output current of the AC / DC converter; the charging of the backup battery unit can be selected during the valley electricity price period.

[0031] Taking the battery pack M1 and battery pack M2 each containing 24 2V lead-acid batteries with a nominal voltage of 48V and a capacity of 200Ah as an example, in the sampling module, one sampling module is configured for every 6 battery cells to collect voltage and temperature data; Communication module: Supports daisy-chain communication with a transmission rate of 1Mbps. AC / DC converter: Rated power is 15kW, and the output voltage range is adjustable from 45 - 58V. Bidirectional DC / DC converter: Rated power is 10kW, supporting input and output of 40 - 60V. The power switch is a relay switch: Rated current is 100A, and the response time <10ms. The BMS control board program is programmed in C language, combining core algorithms: battery state of charge (SOC) estimation algorithm (extended Kalman filter), relay switch switching logic control algorithm, and voltage and current PID regulation algorithm. Adopting the daisy-chain communication protocol, a custom frame format is defined, including battery module ID, cell number, data check bit. The BMS control board communicates with the converter using the Modbus RTU protocol at a baud rate of 9600bps.

[0032] Peak-time discharging, electricity price > 1.2 yuan / kWh: The BMS control board detects the SOC of the backup battery unit. If both battery pack M1 and battery pack M2 are > 80%, then: Close the relay switches of battery pack M1 and battery pack M2. The bidirectional DC / DC converter outputs 51V, and the AC / DC converter outputs 49V. The load is preferentially powered by the backup battery unit. When the output voltage of battery pack M1 cannot be stabilized at 51V, the BMS control board adjusts the output voltage of the bidirectional DC / DC converter to 49.2V. Battery pack M1 or battery pack M2 continues to discharge until the output voltage of the bidirectional DC / DC converter < 49V. The BMS control board disconnects the relay switch of battery pack M1 or battery pack M2 and closes the relay switch of the other battery pack. The AC / DC converter outputs 53.5V for floating charge.

[0033] Repeat the above process to achieve alternating discharging of M1 and M2.

[0034] Valley-time charging, electricity price < 0.4 yuan / kWh: The BMS control board detects the SOC of the backup battery unit. If the SOC of battery pack M1 or M2 < 90%, the BMS controls the output current of the AC / DC module according to the look-up table current value for cell charging, the maximum output current of the AC / DC converter, and the maximum current that the cable can withstand, and outputs a voltage of 54V; Then, charge the battery pack through the bidirectional DC / DC converter. The charging voltage is the total voltage of the battery pack + 3V, and the charging current is Min(system power supply capacity, look-up table current value for cell charging). The look-up table current value for cell charging is related to cell voltage and temperature and belongs to cell characteristics until the battery pack is charged to SOC 100%. The daily average power consumption of a certain base station is 60 Kwh, and the electricity bill is about 60 yuan. The peak-valley electricity price difference in the local area is 0.8 yuan / kWh. With the backup battery unit of this patent, 1 battery pack with 10 Kwh of electricity can be used for peak-valley arbitrage every day, saving 8 yuan in electricity bills every day and reducing costs by about 13%. The dual-battery-pack redundant design reduces the number of power outages throughout the year from 3 times to 0 times. Certainly, without departing from the spirit and essence of the present invention, those skilled in the art should be able to make various corresponding changes and deformations according to the present invention, but these corresponding changes and deformations should all fall within the protection scope of the appended claims of the present invention.

Claims

1. A high-voltage architecture for series-parallel integrated reserve of base stations, comprising a DC bus connected to a load and a backup battery unit, characterized in that: It also includes an AC / DC converter; a bidirectional DC / DC converter; a battery pack M2 with the same power as the battery pack M1; The battery pack M1 and the battery pack M2 are respectively connected in parallel through a power switch to form a backup power battery unit; The DC bus is connected to the AC input terminal through the AC / DC converter and is connected to the backup power battery unit through the bidirectional DC / DC converter.

2. The high-voltage architecture of the base station with series-parallel reserve integration according to claim 1, wherein: The load end of the AC / DC converter is directly connected to the bidirectional DC / DC converter through DC power and is connected to the load through a power switch; the battery end of the bidirectional DC / DC converter is directly connected to the backup power battery unit through DC power.

3. A high-voltage architecture with integrated series and parallel reserves for base stations according to claim 2, characterized in that: The backup power battery unit further includes a BMS control board and a battery pack. The battery pack is composed of battery modules. The battery module includes a sampling module, a communication module, and a cell module; the sampling module is connected to the BMS control board through the communication module; the two sampling modules perform data transmission through the daisy chain communication method; after the communication modules of the two battery modules are connected in series through a communication line, they are connected to the BMS control board.

4. A high-voltage architecture for integrated series and parallel reserves of base stations according to claim 3, characterized in that: The BMS control board controls the output of the AC / DC converter, and the output power is adjusted in real time according to the power consumed by the load and the required power of the backup power battery unit; the output current value changes according to the real-time output power.

5. A high-voltage architecture for integrated series and parallel reserve of base stations according to claim 3, characterized in that: When the backup power battery unit discharges, the DC voltage output by the backup power battery unit through the bidirectional DC / DC converter is higher than the DC voltage at the load end.

6. A control method for integrated series and parallel reserve of base stations, characterized in that: It includes the following steps: Step 1: Add a battery pack M2 with the same power as the battery pack M1, and connect them in parallel through a power switch respectively to form a backup power battery unit; the sampling module in the backup power battery unit collects the current, voltage, and temperature information of the cell module and is connected to the BMS control board through the communication module; the DC bus is connected to the AC input terminal through the AC / DC converter and is connected to the backup power battery unit through the bidirectional DC / DC converter; the load end of the AC / DC converter is directly connected to the bidirectional DC / DC converter through DC power and is connected to the load through a power switch; the battery end of the bidirectional DC / DC converter is directly connected to the backup power battery unit through DC power; Step 2: The 220V alternating current is converted into DC power at the load end through the AC / DC converter, and the DC power at the load end supplies power to the load; Step 3: The DC power at the load end is converted into DC power at the battery end through the bidirectional DC / DC converter to charge the backup power battery unit.

7. A control method for series and parallel reserve integration of a base station according to claim 6, characterized in that: In Step 2, the 220V alternating current is converted into DC power at the load end through the AC / DC converter, and the DC power supplies power to the load. At this time, the backup power battery unit is in a standby discharge state, and the DC voltage output after passing through the bidirectional DC / DC converter is lower than the DC voltage at the load end: In the peak stage of the electricity price wave, the BMS control board adjusts the output voltage of the AC / DC converter to the secondary power-off voltage +1V, and the output voltage of the bidirectional DC / DC converter to the secondary power-off voltage +3V; When the power of battery pack M1 or battery pack M2 is low and the output voltage cannot be stabilized at the secondary under-voltage + 3V, the BMS control board adjusts the output voltage of the bidirectional DC / DC converter to the secondary under-voltage + 1.2V; the battery pack continues to discharge until the output voltage of the bidirectional DC / DC converter is lower than the output voltage of the AC / DC converter, and then the AC / DC converter supplies power to the load. At this time, the BMS control board disconnects the relay switch of the discharged cut-off battery pack and closes the relay switch of the other battery pack, and at the same time adjusts the output voltage of the AC / DC converter to the floating charge voltage.

8. A control method for a base station with series-parallel reserve integration according to claim 6, characterized in that: Specifically, in step 3, the DC power at the load end is converted into DC power at the battery end through the bidirectional DC / DC converter to charge the backup battery unit: the BMS control board controls the output current value of the AC / DC converter to change according to the real-time output power. The charging of the backup battery unit can be selected to be carried out during the valley stage of the electricity price.

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