CN211556956U - High-reliability direct-current power supply for transformer substation - Google Patents

Abstract

The utility model discloses a transformer substation uses high reliability DC power supply. In order to overcome the defects of series connection of battery packs of a direct current power supply system, poor reliability and single lagging effect in the prior art; when the AC is lost and the DC load is short-circuited, the short-circuit current can not be cut off. The utility model adopts a bus, an AC/DC module, a breaker, a DC load, a DC/DC module and a battery module; the bus at the input end of the AC/DC module is an alternating current bus, the bus at the output end of the AC/DC module is a direct current bus, the direct current bus is connected with a direct current load, and the breaker is arranged on the direct current bus; the battery module comprises a plurality of battery packs connected in parallel, and each battery pack is connected with a DC/DC module; the DC/DC module is connected with the direct current bus; and guide elements are arranged between the battery pack and the direct current bus and between the battery packs. The supply of a direct current power supply is ensured, the problem of the lagging effect of a single battery is solved, and the reliability is improved; when short circuit occurs, the circuit breaker is provided with cut-off current, and the safety is improved.

Description

A high-reliability DC power supply for substations

technical field

The utility model relates to the field of a direct current power supply system for a substation, in particular to a high reliability direct current power supply for a substation.

Background technique

The DC system power supply is the power supply for the relay protection and automatic control devices in the substation. As the only backup power supply for the DC system to work normally, the battery pack is the core component of the DC system, and its power supply reliability plays an important role in the safe operation of the power system. effect.

At present, the power supply scheme of the DC system is: 380V AC is converted into 110V or 220V DC to supply power to the system, and there is a set of batteries for backup. When the AC is abnormal, the battery pack supplies power. There is only one battery pack for the backup power supply. When the AC is abnormal, if the battery pack also fails, the DC system will lose power; the replacement process for battery replacement is complicated. The battery group is connected in series, and a single fault will cause the entire group to fail, that is, a single lag effect. Various indicators cannot be collected in real time during the charge and discharge test; the real-time monitoring function is not perfect, the operation status and performance change trend of the battery cannot be fully grasped, and the early warning cannot be timely to eliminate hidden troubles. If the DC load is short-circuited, because the DC/DC power supply current has an upper limit, it cannot provide the tripping current of the circuit breaker and cannot cut off the short-circuit current.

For example, a "substation DC power supply system" disclosed in Chinese patent documents, its bulletin number "CN203481883U", includes a battery module group, the battery module group includes a plurality of parallel battery modules, each of the battery modules The module includes an AC/DC charging module, a lithium iron phosphate battery pack and a DC/DC booster module; the substation DC power supply system further includes a power supply current adjustment module, a charge and discharge current adjustment module, a protection device and a battery management module; the power supply The current adjustment module, the charge and discharge current adjustment module, the protection device, and the battery management module are all electrically connected to the battery module group. Although the power supply system adopts the structure of parallel battery modules, if there is a short circuit at the DC load, due to the upper limit of the DC/DC supply current, it cannot provide the trip current of the circuit breaker, and cannot cut off the short-circuit current. The response speed of the supporting bus voltage is also affected by the DC/DC. DC performance impact.

Utility model content

The utility model mainly solves the problem that the battery packs of the prior art DC power supply system are connected in series, the reliability is poor, and there is a single backward effect; when the DC load is short-circuited, the short-circuit current cannot be cut off; When the AC is abnormal and the battery pack also fails, the DC system will lose power and the single backward effect of the DC power system battery module, and solve the problem that the short-circuit current cannot be cut off when the DC load is short-circuited.

The above-mentioned technical problems of the present utility model are mainly solved by the following technical solutions:

The utility model comprises a busbar, an AC/DC module, a circuit breaker and a DC load; the busbar at the input end of the AC/DC module is an AC busbar, the busbar at the output end of the AC/DC module is a DC busbar, and the DC busbar includes a plurality of DC outlet wires, each DC outlet wire Both are connected to the DC load, and the circuit breaker is arranged on the DC outlet; it is characterized in that the DC power supply further includes a bidirectional DC/DC module and a battery module, and the battery module includes a number of parallel battery packs, and each battery pack is connected with one A bidirectional DC/DC module; the bidirectional DC/DC module is connected with the DC bus; a guiding element is arranged between the battery pack and the DC bus.

Using the battery pack in parallel instead of the series scheme, a battery module includes several battery packs, and the battery packs serve as backups for each other. When several battery packs fail, even if only one set of batteries is left, the power supply can be maintained to ensure no power loss. Considering the reality, one battery module includes 3 or 4 battery packs. When the battery packs are connected in parallel instead of in series, the corresponding number of batteries in each battery pack is reduced. Considering the actual situation, when there are 3 battery packs, each battery pack includes 18 batteries, and when there are 4 battery packs, each battery pack includes 13 batteries; It weakens the single backward effect, reduces the probability of failure, and improves the reliability of the DC system. The use of parallel battery packs can directly replace the faulty battery pack when the battery pack fails, without affecting the normal operation of the DC system; the replacement process is simple, and there is no need to install a backup battery first, replace the faulty battery pack, and then remove it spare battery. The procedure of replacing the backup battery pack is simple, convenient and safe.

A guiding element is arranged between the DC bus bar and the battery pack, and the battery pack is connected in series through the guiding element and connected to the DC bus bar. When the DC load is short-circuited, a breaking current is provided to the circuit breaker to protect the DC system and improve the reliability of the DC system. The battery in series is directly connected to the DC bus, and can provide voltage instantaneously when the DC bus loses voltage until the DC/DC starts to work, supporting the voltage, which further improves the power supply reliability of the DC load.

Preferably, the guiding element is a diode, and the diode includes a diode D5 and a diode D8; the battery packs are connected in series to form a series battery pack; the anode of the diode D5 is connected to the negative bus of the DC bus, and the cathode of the diode D5 is connected to the series-connected battery pack The anode of the diode D8 is connected to the anode of the series battery pack, and the cathode of the diode D8 is connected to the positive bus of the DC bus. Because of the reverse cut-off characteristic of the diode, when the DC bus voltage is normal, the series circuit of the battery pack does not conduct; when the DC bus DC load is short-circuited, the voltage drop of the DC bus is 0, the series circuit is conducted, and the circuit breaker provides opening The current is cut off to ensure that the circuit breaker can operate normally when the DC load is short-circuited, which ensures the reliability and safety of the DC system.

Preferably, the DC power supply further includes a monitoring unit and a host computer, and the monitoring unit includes a monitoring chip and a voltage sensor, a temperature sensor, and a current sensor connected to the monitoring chip; the voltage sensor, temperature sensor, and current sensor are connected to the On the battery module, the monitoring chip is connected with the control terminal of the DC/DC module, and the monitoring chip is connected with the upper computer through a communication protocol. The monitoring unit monitors the current, voltage and temperature data of the battery module, and the monitoring chip uploads the data to the host computer to facilitate data recording, storage and observation. The monitoring unit uses a touch-type microcomputer monitor, the model is KXT05. The monitoring chip is connected to the host computer and the control terminal of the DC/DC module, which is convenient for the remote control of the staff.

Preferably, the bidirectional DC/DC module is an isolated bidirectional DC/DC module; the bidirectional DC/DC module includes an isolated DC step-down circuit and an isolated DC boost circuit; the DC step-down circuit The circuit structure of the DC boost circuit is the same as that of the DC boost circuit. The DC boost circuit is connected in reverse parallel with the DC step-down circuit; the input end of the DC step-down circuit is connected to the output end of the DC boost circuit, and the output end of the DC step-down circuit is connected to the DC boost circuit. the input of the circuit. The bidirectional DC/DC module is selected. The DC/DC module can not only charge the battery pack from the DC bus, but also discharge from the battery pack to the DC bus through the DC/DC module. The system has a simple structure and complete functions. The charging and discharging of the battery pack by the bidirectional DC/DC module is realized according to the difference between the output voltage of the bidirectional DC/DC module and the DC bus voltage and the switching state of the blocking switch S1, without program control, low delay, fast response.

Preferably, the bidirectional DC/DC module further includes a diode D6, a diode D7, a blocking switch S1 and an interlocking switch S2; the first end of the interlocking switch S2 is connected to the positive bus of the DC bus, and the second end of the interlocking switch S2 The terminal is connected to the first terminal of the blocking switch S1, the second terminal of the blocking switch S2 is connected to the positive input terminal of the DC step-down circuit; the negative input terminal of the DC step-down circuit is connected to the negative bus bar of the DC bus, and the positive output terminal of the DC step-down circuit Connect the anode of diode D6, the cathode of diode D6 is connected to the positive terminal of the battery pack, the negative output terminal of the DC step-down circuit is connected to the negative terminal of the battery pack; the input terminal of the DC boost circuit is connected to the battery pack, and the positive output terminal of the DC boost circuit is connected The anode of the diode D7 is connected, the cathode of the diode D7 is connected to the second end of the interlock switch S2, and the negative output end of the DC boost circuit is connected to the negative bus of the DC bus. Diode D6 and diode D7 play a guiding role to prevent the danger caused by current backflow. An interlock switch S2 is set between the bidirectional DC/DC module and the DC bus, and a blocking switch S1 is set at the input end of the DC step-down circuit. The blocking switch S1 controls the charging and blocking of the battery pack, and the interlock switch S2 is used for remote charging and discharging When charging and discharging, it is ensured that only one battery pack is charged and discharged, the charging and discharging status of each battery pack can be controlled separately, and the mutual locking function of each battery pack can be realized to ensure that only one battery pack is in the charging and discharging status.

Preferably, the isolated DC step-down circuit includes a first controllable switch, a second controllable switch, a third controllable switch, a fourth controllable switch, a diode D1, a diode D2, a diode D3, a diode D4, Inductor L1, capacitor C1 and transformer T1; the first end of the second controllable switch is used as the positive input end of the DC step-down circuit, the second end of the second controllable switch is connected to the first end of the first controllable switch, and the first end of the second controllable switch is connected to the first end of the first controllable switch. The second end of the controllable switch is used as the negative input end of the DC step-down circuit; the first end of the fourth controllable switch is connected to the first end of the second controllable switch, and the second end of the fourth controllable switch is connected to the third energy The first end of the control switch, the second end of the third control switch is connected to the second end of the first control switch; the cathode of the diode D1 is connected to the anode of the diode D2; the cathode of the diode D3 is connected to the anode of the diode D4; The anode is connected to the anode of the diode D3, the cathode of the diode D4 is connected to the cathode of the diode D2; the first input terminal of the primary side of the transformer T1 is connected to the second terminal of the second switch tube, and the second input terminal of the primary side of the transformer T1 is connected to the fourth switch tube The second end of the secondary side of the transformer T1 is connected to the anode of the diode D2, the second output end of the secondary side of the transformer T1 is connected to the anode of the diode D4; the first input end of the primary side of the transformer T1 is connected to the anode of the primary side of the transformer T1 The first output terminal is the same name terminal; the anode of diode D3 is connected to the first terminal of capacitor C1, the cathode of diode D4 is connected to the first terminal of inductor L1, and the second terminal of inductor L1 is connected to the second terminal of capacitor C1; One end serves as the negative output end of the DC step-down circuit, and the second end of the capacitor C1 serves as the positive output end of the DC step-down circuit. The inductor L1 stabilizes the current, and the capacitor C1 stabilizes the current. The DC step-down circuit charges the battery pack, the AC/DC module converts the alternating current into a DC voltage of 110V, the turn-on voltage of the DC step-down module is 109V, and the DC step-down circuit reduces the 110V voltage of the DC bus to a lower level, which is used in the battery pack. battery charge. Because the DC boost circuit and the DC step-down circuit have the same structure and are connected in reverse parallel, the output voltage of the DC boost circuit is 108V. When the DC bus is normally powered, the DC bus voltage is 110V. When the voltage of the DC bus is greater than the charging voltage of the DC/DC module, and the charging function is not blocked, the DC bus charges the battery pack; when the voltage of the DC bus is less than the voltage of the output terminal of the DC/DC module, the battery pack is discharged. The circuit structure is simple, no program control is required, and it is realized by voltage difference, with low delay and fast response speed. In addition, the transformer is used to isolate the electrical connection between the battery pack and the DC bus, and the safety is improved.

Preferably, the locking switch S1, the interlocking switch S2 and the controllable switch are all electromagnetic switches. Using the electromagnetic switch, the control method is simple and the cost is low.

Preferably, the blocking switch S1 and the controllable switch are N-channel MOS transistors, the first ends of the blocking switch S1 and the controllable switch are the drains of the MOS transistors, and the second ends of the blocking switch S1 and the controllable switch are The source of the MOS tube. Using N-channel MOS tube as the switch, the cost is low, the control method is simple, and the anti-interference ability is strong.

Preferably, each battery pack includes 18 batteries connected in series. The number of batteries in a single battery pack is reduced to 18, which reduces the number of batteries in each battery pack, reduces the probability of failure of the battery pack due to the single backward effect, and improves the reliability and safety of the DC power supply.

The beneficial effects of the present utility model are:

1. The use of parallel battery packs reduces the probability of failure due to the single backward effect, reduces the probability of battery module failure, and improves the reliability of the DC power supply.

2. A diode is arranged between the DC bus and the battery pack, which is normally cut off, and provides breaking current for the circuit breaker when the load is short-circuited, ensuring the safety and reliability of the DC power supply.

3. The battery in series is directly connected to the DC bus. When the DC bus loses voltage, it can provide voltage instantaneously until the DC/DC starts to work to support the voltage, which improves the reliability of the DC load power supply.

4. Using parallel battery packs, no additional equipment is required for fault replacement, and no power failure is required. The process of replacing battery packs is simple and efficiency is improved.

5. The monitoring unit monitors the status of the battery module, connects to the host computer, and remotely controls the charging and discharging of the battery pack, saving manpower and avoiding errors in manual detection.

6. The bidirectional DC/DC module is used. The bidirectional DC/DC module realizes the charging and discharging function according to the voltage difference and the switching state of the blocking switch S1, without program control, with fast response speed and low delay.

7. The bidirectional DC/DC module has transformer isolation, which isolates the electrical connection between the battery pack and the DC bus and improves safety.

Description of drawings

FIG. 1 is a block diagram of a circuit principle connection structure of the present invention.

Figure 2 is a block diagram of the connection structure of a monitoring unit of the present invention.

FIG. 3 is a circuit diagram of a bidirectional DC/DC module of the present invention.

In the picture 1. AC/DC module, 2. circuit breaker, 3. DC load, 4. battery pack, 5. DC/DC module, 51. DC step-down circuit, 52. DC boost circuit, 6. battery module, 7. Monitoring unit, 71. Monitoring chip, 72. Voltage sensor, 73. Temperature sensor, 74. Current sensor, 8. Host computer.

Detailed ways

The technical solutions of the present utility model will be further described in detail below through embodiments and in conjunction with the accompanying drawings.

Example:

A high-reliability DC power supply for a substation, as shown in Figure 1, includes a bus bar, an AC/DC module 1, a circuit breaker 2, a DC load 3, a DC/DC module 5, a battery module 6, a monitoring unit 7 and a host computer 8 .

The busbar at the input end of the AC/DC module 1 is an AC busbar, and the busbar at the output end of the AC/DC module 1 is a DC busbar. The AC bus includes the live line L and the neutral line N, and the DC bus includes the positive bus M+ and the negative bus M-. The DC bus includes several DC outlet lines, each DC occurrence is connected to the DC load 3 , and the circuit breaker 2 is arranged between the DC outlet wire and the DC load 3 . When a circuit breaker 2 is open for protection, the DC loads of other DC outgoing lines can still continue to work. The battery module 6 is connected to the DC/DC module 5, and the DC/DC module 5 is connected to the DC bus. The monitoring unit 7 is connected to the control terminals of the battery module 6 and the DC/DC module 5, and the monitoring unit 7 is connected to the upper computer 8 through a communication protocol.

The battery module 6 includes a plurality of parallel battery packs 4, each battery pack 4 is connected with a DC/DC module 5, and the DC/DC module 5 is connected with the DC bus. Each battery pack includes 18 batteries connected in series. The number of batteries in a single battery pack is reduced to 18, which reduces the number of batteries in each battery pack, reduces the probability of failure of the battery pack due to the single-battery lag effect, and improves the reliability of the DC power supply.

This embodiment adopts the battery packs 4 connected in parallel, so that when the battery pack 4 fails, the faulty battery pack can be directly replaced without affecting the normal operation of the DC system; the replacement process is simple, and it is not necessary to install a backup battery first to perform the faulty battery pack. replacement, and then remove the backup battery. The process of replacing the backup battery pack is simple, convenient and safe, and the work efficiency is improved.

Instead of the series solution, the battery packs 4 are used in parallel, and one battery module 6 includes three or four battery packs 4 in parallel, in this embodiment, three battery packs 4 in parallel. The battery packs 4 serve as backups for each other. When one or more battery packs 4 fail, even if only one battery pack is left, the power supply can be maintained, and no power loss can be guaranteed. When the AC is abnormal and part of the battery pack 4 in the battery module 6 fails, the DC system still has power supply; the failure of a single or part of the battery pack 4 in the battery module 6 will not cause the entire battery module 6 to fail; The number of batteries is reduced, which weakens the single backward effect, reduces the probability of failure, and improves the reliability of the DC system; the series battery is directly connected to the DC bus, and when the DC bus loses voltage, it can instantly provide voltage until the DC/DC starts to work , support the voltage, and improve the reliability of the DC power supply.

A diode is provided between the battery module 6 and the DC bus. In this embodiment, the diodes include diodes D5 and D8.

The battery packs are connected in series in sequence to form a series battery pack. In this embodiment, the battery packs from the side close to the AC/DC module 1 to the side close to the circuit breaker 2 are the first battery pack, the second battery pack and the third battery pack in order. The positive pole of the first battery pack is connected to the negative pole of the second battery pack, and the positive pole of the second battery pack is connected to the negative pole of the third battery pack; the anode of the diode D5 is connected to the negative busbar M- of the DC bus, and the cathode of the diode D5 is connected to the first battery pack Negative electrode; the anode of the diode D8 is connected to the anode of the third battery pack, and the cathode of the diode D8 is connected to the positive busbar M+ of the DC busbar.

Because of the reverse cut-off characteristic of the diode, when the DC bus voltage is normal, the series circuit of the battery pack 4 does not conduct; when the DC bus DC load 3 is short-circuited, the voltage of the DC bus drops to zero, and the series circuit of the battery pack 4 conducts , to provide breaking current for the circuit breaker, to ensure that the circuit breaker can operate normally when the DC load is short-circuited, and to ensure the reliability and safety of the DC system.

As shown in FIG. 2 , the monitoring unit 7 includes a monitoring chip 71 and a voltage sensor 72 , a temperature sensor 73 , and a current sensor 74 connected to the monitoring chip 71 ; the voltage sensor 72 , the temperature sensor 73 and the current sensor 74 are connected to the battery On the module 6, the monitoring chip 71 is connected to the control terminal of the DC/DC module 5, and the monitoring chip 71 is connected to the upper computer 8 through a communication protocol.

The monitoring unit 7 monitors the current, voltage and temperature data of the battery module 6 through the current sensor 74, the voltage sensor 72 and the temperature sensor 73 respectively, and the monitoring chip 71 uploads the data to the host computer 8 to facilitate data recording, storage and observation. Save manpower to read monitoring data, avoid manual errors, and save manpower. The monitoring unit 8 uses a touch-type microcomputer monitor, the model is KXT05. The monitoring chip 71 is connected to the control terminal of the host computer 8 and the DC/DC module 5, which facilitates the staff to remotely control the battery module 6 for charging and discharging experiments, saves manpower and facilitates control.

As shown in FIG. 3 , the bidirectional DC/DC module 5 is a bidirectional DC/DC module 5 with isolation. The bidirectional DC/DC module 5 includes a DC step-down circuit 51 with isolation, a DC boost circuit 52 with isolation, a diode D6, a diode D7, a blocking switch S1 and an interlocking switch S2. The DC step-down circuit 51 and the DC step-up circuit 52 have the same circuit structure, and the DC step-up circuit 52 and the DC step-down circuit 51 are connected in reverse parallel. In this embodiment, the blocking switch S1 is an N-channel MOS transistor, and the interlocking switch S2 is an electromagnetic switch.

The DC step-down circuit 51 includes a first controllable switch, a second controllable switch, a third controllable switch, a fourth controllable switch, a diode D1, a diode D2, a diode D3, a diode D4, an inductance L1, a capacitor C1 and a transformer T1 . The first controllable switch is an N-channel MOS transistor Q1 with a protection diode, the second controllable switch is an N-channel MOS transistor Q2 with a protection diode, and the third controllable switch is an N-channel MOS transistor Q3 with a protection diode , and the fourth controllable switch is an N-channel MOS transistor Q4 with a protection diode.

The drain of the MOS transistor Q2 serves as the positive input of the DC step-down circuit 51 , the source of the MOS transistor Q2 is connected to the drain of the MOS transistor Q1 , and the source of the MOS transistor Q1 serves as the negative input of the DC step-down circuit 51 . The drain of the MOS transistor Q4 is connected to the drain of the MOS transistor Q2, the source of the MOS transistor Q4 is connected to the drain of the MSO transistor Q3, and the source of the MOS transistor Q3 is connected to the source of the MOS transistor Q1. The cathode of diode D1 is connected to the anode of diode D2, the cathode of diode D3 is connected to the anode of diode D4; the anode of diode D1 is connected to the anode of diode D3, and the cathode of diode D4 is connected to the cathode of diode D2. The first input terminal of the primary side of the transformer T1 is connected to the source of the MOS transistor Q2, the second input terminal of the primary side of the transformer T1 is connected to the source of the MOS transistor Q4, and the first output terminal of the secondary side of the transformer T1 is connected to the anode of the diode D2. The second output terminal of the secondary side of T1 is connected to the anode of the diode D4; the first input terminal of the primary side of the transformer T1 and the first output terminal of the primary side of the transformer T1 are terminals with the same name.

The anode of the diode D3 is connected to the first end of the capacitor C1, the cathode of the diode D4 is connected to the first end of the inductor L1, and the second end of the inductor L1 is connected to the second end of the capacitor C1; the first end of the capacitor C1 serves as the DC step-down circuit 51 The negative output terminal of the capacitor C1 is used as the positive output terminal of the DC step-down circuit 51 .

The DC step-down circuit 51 charges the battery pack, the AC/DC module 1 converts the AC power to a DC voltage of 110V, and the DC step-down circuit 51 reduces the 110V voltage of the DC bus to a lower level to charge the batteries in the battery pack 4 . The circuit structure is simple, the charging does not need program control, and is realized by the voltage difference and the switching state of the blocking switch S1, with low delay and fast response speed. Using N-channel MOS tube as the switch, the cost is low, the control method is simple, and the anti-interference ability is strong. In addition, the transformer is used to isolate the electrical connection between the battery pack and the DC bus, and the safety is improved.

The DC boost circuit 52 includes a fifth controllable switch, a sixth controllable switch, a seventh controllable switch, an eighth controllable switch, a diode D9, a diode D10, a diode D11, a diode D12, an inductor L2, a capacitor C2 and a transformer T2 . The fifth controllable switch is an N-channel MOS transistor Q5 with a protection diode, the sixth controllable switch is an N-channel MOS transistor Q6 with a protection diode, and the seventh controllable switch is an N-channel MOS transistor Q7 with a protection diode , the eighth controllable switch is an N-channel MOS transistor Q8 with a protection diode.

The drain of the MOS transistor Q6 serves as the positive input of the DC boost circuit 52 , the source of the MOS transistor Q6 is connected to the drain of the MOS transistor Q5 , and the source of the MOS transistor Q5 serves as the negative input of the DC boost circuit 52 . The drain of the MOS transistor Q8 is connected to the drain of the MOS transistor Q6, the source of the MOS transistor Q8 is connected to the drain of the MSO transistor Q7, and the source of the MOS transistor Q7 is connected to the source of the MOS transistor Q5. The cathode of diode D9 is connected to the anode of diode D10, the cathode of diode D11 is connected to the anode of diode D12; the anode of diode D9 is connected to the anode of diode D11, and the cathode of diode D12 is connected to the cathode of diode D10. The first input terminal of the primary side of the transformer T1 is connected to the source of the MOS transistor Q6, the second input terminal of the primary side of the transformer T1 is connected to the source of the MOS transistor Q8, and the first output terminal of the secondary side of the transformer T1 is connected to the anode of the diode D6. The second output terminal of the secondary side of T1 is connected to the anode of the diode D12; the first input terminal of the primary side of the transformer T1 and the first output terminal of the primary side of the transformer T1 are terminals with the same name.

The anode of the diode D11 is connected to the first end of the capacitor C2, the cathode of the diode D12 is connected to the first end of the inductor L2, and the second end of the inductor L2 is connected to the second end of the capacitor C2; the first end of the capacitor C2 serves as the DC boost circuit 52 The negative output terminal of the capacitor C2 is used as the positive output terminal of the DC boost circuit 52 .

The output voltage of the DC boost circuit is 108V. When the DC bus is powered normally, the voltage of the DC bus is 110V. When the voltage of the DC bus is greater than the charging voltage of the DC/DC module 5 and the charging function is not blocked, the DC bus charges the battery pack; when the voltage of the DC bus is lower than the voltage of the output terminal of the DC/DC module 5, the battery pack is discharged. The circuit structure is simple, no program control is required, and it is realized by voltage difference, with low delay and fast response speed. Using N-channel MOS tube as the switch, the cost is low, the control method is simple, and the anti-interference ability is strong. In addition, the transformer is used to isolate the electrical connection between the battery pack and the DC bus, and the safety is improved.

The first end of the interlock switch S2 is connected to the positive bus M+ of the DC bus, the second end of the interlock switch S2 is connected to the drain of the blocking switch S1, and the source of the blocking switch S2 is connected to the positive input terminal of the DC step-down circuit 51, namely The drain of the MOS transistor Q2. The negative input end of the DC step-down circuit 51, that is, the source of the MOS transistor Q1 is connected to the negative bus M- of the DC bus, and the positive output end of the DC step-down circuit 51, that is, the second end of the capacitor C1 is connected to the anode of the diode D6, and the diode D6 The cathode of the capacitor C1 is connected to the positive terminal of the battery pack 4 , and the negative output terminal of the DC step-down circuit 51 , that is, the first terminal of the capacitor C1 is connected to the negative terminal of the battery pack 4 . The input terminal of the DC boost circuit 51 is connected to the battery pack 4, that is, the drain of the MOS transistor Q6 is connected to the positive terminal of the battery pack 4, and the source of the MOS transistor Q5 is connected to the negative terminal of the battery pack 4; the positive output of the DC boost circuit 52 The second terminal of the capacitor C2 is connected to the anode of the diode D7, the cathode of the diode D7 is connected to the second terminal of the interlock switch S2, and the negative output terminal of the DC boost circuit 52, that is, the first terminal of the capacitor C2 is connected to the DC bus. Negative bus M-.

The locking switch S1 controls the charging and locking of the battery pack, and the interlock switch S2 ensures that only one battery pack is charged and discharged during remote charging and discharging.

The bidirectional DC/DC module 5 is selected. The DC/DC module 5 can not only charge the battery pack 4 from the DC bus, but also discharge from the 4-phase DC bus of the battery pack through the DC/DC module 5. The structure is simple and the function is complete. The bidirectional DC/DC module 5 uses a transformer to isolate the electrical connection between the battery pack 4 and the DC bus, thereby improving safety. The charging and discharging of the battery pack 4 is realized by the voltage difference between the output voltage of the bidirectional DC/DC module 5 and the DC bus voltage, and no program control is required. 5 Discharge, low latency and fast response.

Under normal conditions, the battery pack 4 is automatically charged during:

The 380V AC power is converted into 110V DC voltage through AC/DC module 1, and output to the DC bus; at the same time, the DC voltage at the DC bus is 110V to reach the charging voltage of 109V by the bidirectional DC/DC module 5, and the bidirectional DC/DC module 5 charging function Turn on to charge the battery pack 4. The charging process does not require voltage monitoring and control, and is automatically performed when the DC bus voltage reaches the charging turn-on voltage. The output voltage of the bidirectional DC/DC module 5 is 108V lower than the DC bus voltage, and the discharge function is turned off.

In the case of abnormal AC, the battery pack 4 automatically discharges the process:

When the AC abnormality causes the DC bus voltage to drop, the output voltage of the bidirectional DC/DC module 5 is 108V greater than the DC bus voltage, the discharge function is quickly turned on, and the battery pack 4 automatically discharges to supply power to the DC bus. The discharge process also does not require voltage monitoring and control. At the same time, the voltage at the DC bus is not enough to reach the charging turn-on voltage of the bidirectional DC/DC module 5 of 109V, and the charging function of the bidirectional DC/DC module 5 is turned off.

The bidirectional DC/DC module 5 is selected. The DC/DC module 5 can not only charge the battery pack 4 from the DC bus, but also discharge from the 4-phase DC bus of the battery pack through the DC/DC module 5. The charging and discharging state of the battery pack is determined by the bidirectional DC. The voltage difference between the output voltage of the /DC module and the DC bus voltage is controlled without program control. When the DC bus loses power, the battery pack can be discharged through the bidirectional DC/DC module, with fast response time and low delay. The entire DC system has a simple structure and complete functions. An interlock switch is arranged between the bidirectional DC/DC module 5 and the DC bus, and a lock switch is arranged at the input end of the DC step-down module. The lock switch controls the charging lock of the battery pack, and the interlock switch ensures the remote charging and discharging. Only one battery pack is charged and discharged, and the charge and discharge states of each battery pack can be controlled separately, realizing the mutual blocking function between the battery packs, ensuring that only one battery pack is in the charging and discharging state.

The utility model patent uses parallel battery packs, which reduces the number of batteries in each battery pack, reduces the probability of failure due to the single backward effect, reduces the probability of battery module failure, and improves the reliability of the DC power supply. There is no need for additional equipment or power failure during fault replacement, the process of replacing the battery pack is simple, and the efficiency is improved. A diode is arranged between the DC bus bar and the battery pack, which is normally cut off and provides a breaking current for the circuit breaker when the load is short-circuited, ensuring the safety and reliability of the DC power supply. The monitoring unit monitors the status of the battery module, connects to the host computer, and remotely controls the charging and discharging of the battery pack, saving manpower and avoiding errors in manual detection. The bidirectional DC/DC module is used, and the bidirectional DC/DC module realizes the charging and discharging function through the voltage difference, with fast response speed and no delay. The entire DC power supply has a simple structure, complete functions and low cost.

Claims (9)

1. A high-reliability DC power supply for a substation, comprising a busbar, an AC/DC module (1), a circuit breaker (2) and a DC load (3); the busbar at the input end of the AC/DC module (1) is an AC busbar, an AC busbar The busbar at the output end of the DC module (1) is a DC busbar, and the DC busbar includes a plurality of DC outlet wires, each DC outlet wire is connected to a DC load (3), and the circuit breaker (2) is arranged on the DC outlet wire; it is characterized in that the described The DC power supply further includes a bidirectional DC/DC module (5) and a battery module (6), the battery module (6) includes a plurality of parallel battery packs (4), and each battery pack (4) is connected with a bidirectional DC/DC module (5); the bidirectional DC/DC module (5) is connected with the DC bus; a guiding element is arranged between the battery pack (4) and the DC bus. 2. A high-reliability DC power supply for a substation according to claim 1, wherein the guiding element is a diode, and the diode comprises a diode D5 and a diode D8; the battery packs (4) are connected in series to form Connect the battery pack in series; the anode of diode D5 is connected to the negative bus of the DC bus, the cathode of diode D5 is connected to the cathode of the series battery pack; the anode of diode D8 is connected to the anode of the series battery pack, and the cathode of diode D8 is connected to the positive bus of the DC bus. 3. A high-reliability DC power supply for a substation according to claim 1, wherein the DC power supply further comprises a monitoring unit (7) and a host computer (8); the monitoring unit (7) comprises a monitoring chip (71) and a voltage sensor (72), a temperature sensor (73), and a current sensor (74) connected to the monitoring chip (71); the voltage sensor (72), temperature sensor (73) and current sensor (74) ) is connected to the battery module (6), the monitoring chip (71) is connected to the control terminal of the DC/DC module (5), and the monitoring chip (71) is connected to the host computer (8) through a communication protocol. 4. A high-reliability DC power supply for a substation according to claim 1 or 3, wherein the bidirectional DC/DC module (5) is a bidirectional DC/DC module (5) with isolation; The DC/DC module (5) includes a DC step-down circuit (51) with isolation and a DC booster circuit (52) with isolation; the DC step-down circuit (51) and the DC booster circuit (52) are circuits The structure is the same, the DC boost circuit (52) and the DC step-down circuit (51) are inversely connected in parallel; the input end of the DC step-down circuit (51) is connected to the output end of the DC boost circuit (52), and the DC step-down circuit (51) ) is connected to the input of the DC boost circuit (52). 5. A high-reliability DC power supply for a substation according to claim 4, wherein the bidirectional DC/DC module (5) further comprises a diode D6, a diode D7, a blocking switch S1 and an interlocking switch S2 ; The first end of the interlock switch S2 is connected to the positive bus of the DC bus, the second end of the interlock switch S2 is connected to the first end of the blocking switch S1, and the second end of the blocking switch S2 is connected to the positive bus of the DC step-down circuit (51). Input terminal; the negative input terminal of the DC step-down circuit (51) is connected to the negative bus of the DC bus, the positive output terminal of the DC step-down circuit (51) is connected to the anode of the diode D6, and the cathode of the diode D6 is connected to the positive terminal of the battery pack (4). Extreme, the negative output terminal of the DC step-down circuit (51) is connected to the negative terminal of the battery pack (4); the input terminal of the DC boost circuit (52) is connected to the battery pack (4), and the positive output terminal of the DC boost circuit (52) The anode of the diode D7 is connected, the cathode of the diode D7 is connected to the second end of the interlock switch S2, and the negative output end of the DC boost circuit (52) is connected to the negative bus of the DC bus. The high-reliability DC power supply for a substation according to claim 5, wherein the isolated DC step-down circuit (51) comprises a first controllable switch, a second controllable switch, a first controllable switch, a Three controllable switches, fourth controllable switches, diode D1, diode D2, diode D3, diode D4, inductor L1, capacitor C1 and transformer T1; the first end of the second controllable switch is used as the DC voltage step-down circuit (51) The positive input end, the second end of the second controllable switch is connected to the first end of the first controllable switch, and the second end of the first controllable switch serves as the negative input end of the DC step-down circuit (51); the fourth controllable switch The first end of the switch is connected to the first end of the second controllable switch, the second end of the fourth controllable switch is connected to the first end of the third controllable switch, and the second end of the third controllable switch is connected to the first controllable switch. The second end of the switch; the cathode of diode D1 is connected to the anode of diode D2; the cathode of diode D3 is connected to the anode of diode D4; the anode of diode D1 is connected to the anode of diode D3, the cathode of diode D4 is connected to the cathode of diode D2; the primary side of transformer T1 The first input end of the transformer T1 is connected to the second end of the second switch tube, the second input end of the primary side of the transformer T1 is connected to the second end of the fourth switch tube, the first output end of the secondary side of the transformer T1 is connected to the anode of the diode D2, and the transformer T1 is connected to the anode of the diode D2. The second output terminal of the secondary side of T1 is connected to the anode of the diode D4; the first input terminal of the primary side of the transformer T1 and the first output terminal of the primary side of the transformer T1 are the terminals of the same name; the anode of the diode D3 is connected to the first terminal of the capacitor C1, the diode The cathode of D4 is connected to the first end of the inductor L1, and the second end of the inductor L1 is connected to the second end of the capacitor C1; the first end of the capacitor C1 serves as the negative output end of the DC step-down circuit (51), and the second end of the capacitor C1 As the positive output terminal of the DC step-down circuit (51). 7 . The high-reliability DC power supply for a substation according to claim 6 , wherein the locking switch S1 , the interlocking switch S2 and the energy control switch are all electromagnetic switches. 8 . 8 . The high-reliability DC power supply for a substation according to claim 6 , wherein the blocking switch S1 and the controllable switch are N-channel MOS tubes, and the first The terminal is the drain of the MOS tube, and the second terminal of the blocking switch S1 and the controllable switch is the source of the MOS tube. 9 . The high-reliability DC power supply for a substation according to claim 1 , wherein each battery pack ( 4 ) includes 18 batteries connected in series. 10 .

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