CN110021984A - A kind of lithium iron phosphate storage battery discontinuity floating charge method for electrically - Google Patents

Abstract

The invention relates to an intermittent floating charging method for a lithium iron phosphate battery, which provides a DC monitor, a circuit breaker, a contactor, a diode, a lithium iron phosphate battery pack, and a bypass switch; the BMS system of the lithium iron phosphate battery pack is real-time Calculate the SOC of the battery pack and upload it to the DC monitor. The DC monitor judges whether to charge the battery according to the SOC value; when the battery pack needs to be charged, the DC monitor controls the contactor to close, and the lithium iron phosphate battery pack is directly connected in parallel. On the bus, the charger on the bus supplies power to the lithium iron phosphate battery pack; when the battery pack does not need to be charged, the DC monitor controls the contactor to be disconnected, and the lithium iron phosphate battery pack is separated from the DC bus and is in a static state. The invention improves the reliability of the system, ensures that the lithium iron phosphate battery can effectively improve the overall life of the battery pack under the premise of seamless discharge, and minimizes the potential safety hazard caused by the battery consistency problem.

Description

A kind of intermittent floating charging method of lithium iron phosphate battery

technical field

The invention relates to the field of design of a direct current power supply system of a substation, in particular to a method for intermittent floating charging of a lithium iron phosphate battery.

Background technique

It is well known that the battery is an independent backup power supply for the DC system used in the station. The backup power supply provides power for signal, control, closing, and comprehensive automation during AC power failure. It is the last line of defense to ensure the reliability of the DC system.

Because of its small size, light weight, high energy ratio, safety and environmental protection, and maintainability, lithium iron phosphate batteries are more and more widely used in station DC systems. In the prior art, the application of lithium iron phosphate batteries in the DC power supply system is directly hung on the DC bus, and the uninterrupted power supply of the power supply is realized when the AC power is lost.

In the existing DC power supply system based on lithium iron phosphate batteries, due to some characteristic problems of the lithium iron phosphate battery pack itself (for example: poor consistency), the battery pack has a situation of unbalanced cell voltage. If the battery pack is charged for a long time It may cause adverse effects such as overcharging or even fire in some of the cells inside the battery.

SUMMARY OF THE INVENTION

In view of this, the purpose of the present invention is to propose a kind of intermittent floating charging method of lithium iron phosphate battery, which improves the reliability of the system, and ensures that the lithium iron phosphate battery effectively improves the overall life of the battery pack under the premise of seamless discharge, Minimize the safety hazards caused by battery consistency problems.

The present invention adopts the following scheme to realize: a method for intermittent floating charging of lithium iron phosphate battery, comprising a DC monitor in a DC system, a charger electrically connected with a DC bus, providing a circuit breaker, a contactor, a diode, a lithium iron phosphate A battery pack, and a bypass switch; the positive terminal of the circuit breaker switch is connected to one end of the contactor, the cathode of the diode, and one end of the bypass switch, respectively, and the negative terminal of the circuit breaker switch is connected to the lithium iron phosphate battery pack The anode of the diode, the other end of the contactor, the anode of the lithium iron phosphate battery pack, and the other end of the bypass switch are connected; the contactor is controlled by the DC monitor, and the bypass switch is In a normal state, it is in an off state, the circuit breaker is connected to the DC bus, the lithium iron phosphate battery pack is equipped with a BMS system, and the BMS system is communicatively connected to the DC monitor;

The BMS system calculates the battery parameters including the SOC value of the lithium iron phosphate battery pack in real time, and uploads it to the DC monitor, and the DC monitor judges whether To charge the battery; when the battery pack needs to be charged, the DC monitor controls the contactor to close (you can also send a command to the BMS to control the contactor to close), and the lithium iron phosphate battery pack is directly connected to the busbar and connected to the DC busbar The charger on the top supplies power to the lithium iron phosphate battery pack. When the battery pack is not required to be charged, keep the contactor disconnected, and the lithium iron phosphate battery pack is separated from the DC bus and is in a static state;

When the charger connected to the DC bus is in normal operation, the diode is in the reverse state and disconnected. When the battery pack does not need to be charged, the DC monitor controls the contactor to be disconnected, and the lithium iron phosphate battery pack is separated from the DC bus and is at rest If the DC monitor determines that the lithium iron phosphate battery pack needs to be charged and the DC contactor is closed, the battery is directly connected to the busbar in parallel, and the charger supplies power to the DC load and the battery at the same time.

When the charger connected to the DC bus has no output, due to the forward conduction of the reverse diode, the battery can supply power to the DC bus without interruption, so that the reliability of the DC system will not be affected.

Further, the diode adopts a reverse-connected high-power diode to ensure that the discharge loop is always turned on and supports uninterrupted discharge (nanosecond level).

Preferably, when necessary, the bypass switch is controlled to be closed, and when the bypass switch is closed, it is switched to the direct-connected circuit.

Preferably, the BMS system in the lithium iron phosphate battery pack in the present invention can monitor the voltage, current, internal resistance, temperature, SOC and other parameters of the battery in real time, and adjust the time ratio of intermittent floating charging, so as to be most suitable for battery operation. .

Preferably, the DC monitor, as a centralized monitoring and management unit of the DC system, communicates with the BMS, the chargers on the DC bus, etc., to realize monitoring and maintenance management of the DC system of the substation.

In particular, the present invention also configures a passive balance protection device (BPD) in the lithium iron phosphate battery pack, and controls the switching of the BPD through the battery management system (BMS). In the charging state, when the voltage of the single cell reaches the set value, the BPD voltage equalization protection measures are activated to prevent some single cells from being overcharged, and try to achieve that the battery cells tend to be consistent; in the accident or discharge state, all voltage equalization functions Closed to prevent the resistor connected to the single battery from consuming power and causing waste. During the discharge process, the BMS will detect the voltage of each cell and automatically stop the discharge when the discharge cut-off voltage is reached.

Compared with the prior art, the present invention has the following beneficial effects: the present invention adopts the intermittent floating charging strategy, which improves the system reliability compared with the prior art, and ensures that the lithium iron phosphate battery can effectively improve the battery pack under the premise of seamless discharge. The overall lifespan of the battery is minimized, and the safety hazards caused by battery consistency problems are minimized.

Description of drawings

FIG. 1 is a schematic diagram of a circuit principle according to an embodiment of the present invention.

Detailed ways

The present invention will be further described below with reference to the accompanying drawings and embodiments.

It should be noted that the following detailed description is exemplary and intended to provide further explanation of the application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

It should be noted that the terminology used herein is for the purpose of describing specific embodiments only, and is not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly dictates otherwise, the singular is intended to include the plural as well, furthermore, it is to be understood that when the terms "comprising" and/or "including" are used in this specification, it indicates that There are features, steps, operations, devices, components and/or combinations thereof.

As shown in FIG. 1 , this embodiment provides a method for intermittent floating charging of a lithium iron phosphate battery, including a DC monitor in a DC system, a charger electrically connected to the DC bus, providing a circuit breaker, a contactor, a diode , a lithium iron phosphate battery pack, and a bypass switch; the positive terminal of the circuit breaker is connected to one end of the contactor, the cathode of the diode, and one end of the bypass switch, and the negative terminal of the circuit breaker is connected to the phosphoric acid The negative pole of the lithium iron battery pack, the anode of the diode, the other end of the contactor, the positive pole of the lithium iron phosphate battery pack, and the other end of the bypass switch are connected; the contactor is controlled by the DC monitor, the The bypass switch is in an off state in a normal state, the disconnect switch is connected to the DC bus, the lithium iron phosphate battery pack is equipped with a BMS system, and the BMS system is communicatively connected to the DC monitor;

The BMS system calculates the battery parameters including the SOC value of the lithium iron phosphate battery pack in real time, and uploads it to the DC monitor, and the DC monitor judges whether To charge the battery; when the battery pack needs to be charged, the DC monitor controls the contactor to close (it can also send a command to the BMS to control the contactor to close), the lithium iron phosphate battery pack is directly connected to the busbar, and the charging on the busbar The machine supplies power to the lithium iron phosphate battery pack; when the battery pack does not need to be charged, the DC monitor controls the contactor to be disconnected, and the lithium iron phosphate battery pack is separated from the DC bus and is in a static state.

When the charger connected to the DC bus is in normal operation, the diode is in the reverse state and disconnected. When the battery pack does not need to be charged, the DC monitor controls the contactor to be disconnected, and the lithium iron phosphate battery pack is separated from the DC bus and is at rest If the DC monitor determines that the lithium iron phosphate battery pack needs to be charged and the DC contactor is closed, the battery is directly connected to the busbar in parallel, and the charger supplies power to the DC load and the battery at the same time.

When the charger on the DC bus has no output, due to the forward conduction of the reverse diode, the battery can supply power to the DC bus without interruption, so that the reliability of the DC system will not be affected.

In this embodiment, the diode adopts a reverse-connected high-power diode to ensure that the discharge loop is always turned on and supports uninterrupted discharge (nanosecond level).

Preferably, in this embodiment, when necessary, the bypass switch is controlled to be closed, and when the bypass switch is closed, it is switched to the direct-connected circuit.

Preferably, the BMS system in the lithium iron phosphate battery pack of this embodiment can monitor the voltage, current, internal resistance, temperature, SOC and other parameters of the battery in real time, and adjust the time ratio of intermittent floating charging, so as to be most suitable for battery operation. .

Preferably, the DC monitor, as a centralized monitoring and management unit of the DC system, communicates with the BMS, the chargers on the DC bus, etc., to realize monitoring and maintenance management of the DC system of the substation.

In particular, in this embodiment, a passive balance protection device (BPD) is also configured in the lithium iron phosphate battery pack, and the switching of the BPD is controlled by the battery management system (BMS). In the charging state, when the voltage of the single cell reaches the set value, the BPD voltage equalization protection measures are activated to prevent some single cells from being overcharged, and try to make the battery cells tend to be consistent; in the accident or discharge state, all voltage equalization functions Closed to prevent the resistor connected to the single battery from consuming power and causing waste. During the discharge process, the BMS will detect the voltage of each cell and automatically stop the discharge when the discharge cut-off voltage is reached.

This embodiment adopts the charging and discharging control strategy suitable for the lithium iron phosphate DC system of the substation, and combines the passive balance protection measures of the battery system to minimize the difference in the terminal voltage of the single battery, and give full play to the effect of the lithium iron phosphate battery. Extend the service life of the battery and ensure the safe and reliable operation of the lithium iron phosphate DC system in the substation.

As will be appreciated by those skilled in the art, the embodiments of the present application may be provided as a method, a system, or a computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) having computer-usable program code embodied therein.

The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the present application. It will be understood that each flow and/or block in the flowcharts and/or block diagrams, and combinations of flows and/or blocks in the flowcharts and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to the processor of a general purpose computer, special purpose computer, embedded processor or other programmable data processing device to produce a machine such that the instructions executed by the processor of the computer or other programmable data processing device produce Means for implementing the functions specified in one or more of the flowcharts and/or one or more blocks of the block diagrams.

These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory result in an article of manufacture comprising instruction means, the instructions An apparatus implements the functions specified in a flow or flows of the flowcharts and/or a block or blocks of the block diagrams.

These computer program instructions can also be loaded on a computer or other programmable data processing device to cause a series of operational steps to be performed on the computer or other programmable device to produce a computer-implemented process such that The instructions provide steps for implementing the functions specified in one or more of the flowcharts and/or one or more blocks of the block diagrams.

The above are only preferred embodiments of the present invention, and are not intended to limit the present invention in other forms. Any person skilled in the art may use the technical content disclosed above to make changes or modifications to equivalent changes. Example. However, any simple modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solutions of the present invention still belong to the protection scope of the technical solutions of the present invention.

Claims (2)

1. a kind of lithium iron phosphate storage battery discontinuity floating charge method for electrically, including the direct-current supervision device, female with direct current in direct current system The charger that line is electrical connected, it is characterised in that: provide disconnect switch, contactor, diode, lithium iron phosphate storage battery group, with And by-pass switch；The positive terminals of the disconnect switch are respectively connected to one end of contactor, the cathode of diode and bypass One end of switch, the negative terminals of the disconnect switch are connected to the cathode of lithium iron phosphate storage battery group, the sun of the diode Pole, the other end of contactor, the anode of lithium iron phosphate storage battery group and by-pass switch the other end be connected；The contactor It is controlled by the direct-current supervision device, the by-pass switch is being in an off state under normal conditions, the disconnect switch and DC bus It is connected, the lithium iron phosphate storage battery group is equipped with BMS system, which is connected with direct-current supervision device communication；

The BMS system calculates the battery parameter including SOC value of lithium iron phosphate storage battery group in real time, and is uploaded to direct current Monitor, direct-current supervision device determine whether to charge to battery pack according to the battery parameter including SOC value；When needs are to electricity When pond group charges, direct-current supervision device control contactor closure, lithium iron phosphate storage battery group is directly attempted by bus, and charger is given The power supply of lithium iron phosphate storage battery group；When not needing to charge to battery pack, direct-current supervision device control contactor is disconnected, LiFePO4 Battery group is detached from DC bus and is in static condition.

2. a kind of lithium iron phosphate storage battery discontinuity floating charge method for electrically according to claim 1, it is characterised in that: described two Pole pipe uses heavy-duty diode, to ensure that discharge loop is connected always.