KR20130015353A - Battery conditioning system and battery energy storage system including battery conditioning system - Google Patents

Abstract

PURPOSE: A battery managing apparatus and a battery energy storage system are provided to control a voltage imbalance between battery racks by connecting an initial charging unit to the battery rack. CONSTITUTION: A tray(320a-320n) includes one or more batteries. A first switch(330) connects the tray to a power conditioning system. An initial charging unit operates before the first switch is on and prevents an inrush current by initially charging the batteries. A surge voltage is generated by the operation of the initial charging unit.

Description

Battery management device and a battery energy storage system including the same {Battery Conditioning System and Battery Energy Storage System including Battery Conditioning System}

The present invention relates to an energy storage system, and more particularly to control of a battery energy storage system.

With the development of industry, electric power demand is gradually increasing, and the gap of electric power usage between day and night, season and daily is deepening.

Recently, for this reason, many techniques for reducing peak load by utilizing the surplus power of the system have been developed rapidly. Among these technologies, a battery which stores surplus power of the system in the cell or supplies the insufficient power of the system from the battery Battery Energy Storage System.

The battery energy storage system stores surplus power generated at night or surplus power from renewable energy such as wind and solar power and supplies the system with power stored in the battery in case of peak load or system accident. This will stabilize the system power unstably fluctuating by the renewable energy source and achieve maximum load reduction and load leveling.

The battery energy storage system may be used in an intelligent grid, which is recently emerging due to the emergence of various renewable energy sources.

Due to the limitations of battery packing technology, such battery energy storage systems are generally configured by connecting battery racks, which are generally composed of one or more batteries, in parallel with each other.

However, when each battery rack is connected in parallel, an inrush current occurs because the voltages of the battery racks are different, and the inrush current causes a current exceeding the capacity of the device to flow into the device, which causes the device to break or become severe. There is a problem that may occur due to the destruction of the fire.

Disclosure of Invention The present invention has been made in view of the above-described problems, and it is an object of the present invention to provide a battery management apparatus capable of solving voltage imbalance between battery racks included in a battery management apparatus and a battery energy storage system including the same.

In addition, another object of the present invention is to provide a battery management apparatus and a battery energy storage system including the same capable of preventing the generation of inrush current when the battery rack included in the battery management apparatus is connected.

In addition, the present invention provides a battery management device that can prevent the generation of a surge (Surge) due to the on-off operation of the initial charging unit included in the battery management device to prevent inrush current and a battery energy storage system including the same That is another technical problem.

Battery management apparatus according to an aspect of the present invention for achieving the above object, Tray (Tray) consisting of one or more batteries; A first switch connecting the tray to a Power Conditioning System (PCS) for charging and discharging the one or more batteries; An initial charging unit which operates before the first switch is turned on to prevent inrush current generation by initial charging the one or more batteries; And a surge voltage protection unit for absorbing the surge voltage generated by the operation of the initial charging unit through at least one capacitor to remove the surge voltage.

A battery energy storage system according to another aspect of the present invention for achieving the above object, the battery management device including at least one battery rack is charged with surplus energy provided from the system; And a power management device configured to charge the surplus energy in the at least one battery rack, and discharge the energy charged in the at least one battery rack to the system, wherein the battery rack includes one or more batteries. Being a tray; An initial charging unit configured to initially charge the one or more batteries by connecting the tray to the power management device during a time period before the battery energy storage system reaches a normal state; And a surge voltage protection unit absorbing a surge voltage generated by the operation of the initial charging unit through at least one capacitor.

According to the present invention, by connecting the initial charging unit to the battery rack included in the battery management device, it is possible to control the voltage imbalance between the battery racks in parallel connection between the battery racks, thereby preventing the occurrence of inrush current due to the voltage imbalance between the battery racks There is an effect that can be prevented.

In addition, according to the present invention, by adding a Y-capacitor circuit to each battery rack, switching noise generated by an inverter of the power management device that charges and discharges each battery rack as well as minimizes the generation of surge voltage according to the operation of the initial charging unit. And potential imbalance between both ends of the smoothing capacitor included in the power management device.

1 is a view showing a network configuration to which the battery energy storage system according to an embodiment of the present invention is applied.
2 is a block diagram schematically showing the configuration of the battery energy storage system shown in FIG.
3A is a diagram illustrating an electrical configuration of a battery management apparatus according to a first embodiment of the present invention.
3B is a view showing an electrical configuration of the battery management apparatus according to the first embodiment of the present invention.
4 is a graph showing charge and discharge characteristics of a battery.
5A is a graph illustrating surge voltages generated by an operation of an initial charging unit
5B is a graph showing noise generated during communication between battery rack controllers.
6A is a graph showing that generation of a surge voltage is suppressed according to a surge voltage generator.
6B is a graph showing that generation of communication noise is suppressed according to the surge voltage generation unit.
7 is a view showing an electrical configuration of a power management device according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a diagram illustrating a network configuration to which a battery energy storage system (BESS) is applied according to an embodiment of the present invention.

As shown in FIG. 1, the battery energy storage system 100 is connected to a global monitoring system (GMS) 110 and an energy management system (EMS) 120. In this case, the global monitoring system 110 may be connected to the battery energy storage system 100 and the energy management system 120 through the Internet.

First, the global monitoring system 110 is connected to the plurality of battery energy storage systems 100 through the energy management system 110, and the global integrated management, various types of data transmitted from the plurality of battery energy storage systems 100 Collection of data, display of operating status of the plurality of battery energy storage systems 100, analysis of various data transmitted from the plurality of battery energy storage systems 100 (e.g., prediction or inspection of battery life), storage of a plurality of battery energy It performs the function of managing the operation optimization of the system 100, and investment / facility efficiency.

The energy management system 120 may be connected to the plurality of battery energy storage systems 100 to perform operation schedule control of the plurality of battery energy storage systems 100 or may be transmitted from the plurality of battery energy storage systems 100. The various data are reported to the global monitoring system 110, integrated management of the power of the plurality of battery energy storage systems 100, or a function of predicting demand or power generation of a system (not shown).

In addition, the energy management system 120 performs a function such as managing a power transaction history or establishing an optimal power generation plan.

The battery energy storage system 100 receives surplus power generated from wind, solar, etc. from the grid and charges one or more battery racks included in the battery energy storage system 100, and then, in case of a peak load or grid accident, Discharges the power charged in the battery rack to the system to supply power to the system.

Hereinafter, the configuration of the battery energy storage system 100 will be described in more detail with reference to FIG. 2.

2 is a block diagram schematically illustrating the configuration of a battery energy storage system according to an embodiment of the present invention.

As shown in FIG. 2, the battery energy storage system 100 includes a battery management device 210, a power management device 220, and a controller 230.

Although the battery energy storage system 100 illustrated in FIG. 2 is described as including one battery management device 210 and one power management device 220, in the modified embodiment, the battery energy storage system 100 may be described. The plurality of battery management apparatuses 210 and the plurality of power management apparatuses 220 may be included.

First, the Battery Conditioning System (BCS) 210 stores surplus energy supplied from the grid in one or more battery racks, and stores energy stored in the one or more battery racks in the event of a peak load or system accident. Supply.

Hereinafter, the configuration of the battery management apparatus 210 will be described in more detail with reference to FIGS. 3A and 3B.

3A and 3B illustrate an electrical configuration of a battery management apparatus according to an embodiment of the present invention.

As shown in FIGS. 3A and 3B, the battery management apparatus 210 according to an embodiment of the present invention includes one or more battery racks 310 connected in parallel with each other.

As illustrated in FIGS. 3A and 3B, the battery rack 310 includes trays 320a to 320n, first switches 330, initial charging units 340, and surge voltage protection units 350.

First, the trays 320a to 320n are configured by connecting a plurality of modules (not shown) including one or more batteries, and as illustrated in FIGS. 3A and 3B, the battery racks 310 are connected in series to each other. Trays 320a to 320n may be included.

In one embodiment, one module may consist of 24 batteries, one tray may consist of three modules, and one battery rack may consist of eight trays.

Next, the first switch 330 is for connecting the trays 320a to 320n to the power management device 220, and is turned off during the time interval before the battery energy storage system 100 reaches the normal state. In the off state, when the battery energy storage system 100 reaches a normal state, the battery energy storage system 100 is turned on to connect the trays 320a to 320n to the power management device 220.

The batteries of the trays 320a to 320n connected to the power management device 220 through the first switch 330 are charged and discharged by the power management device 220.

Next, when the one or more battery racks 310 are connected to the power management device 220, the initial charging unit 340 serves to prevent inrush current that may be generated due to the voltage difference between the battery racks 310. To perform.

Here, the inrush current is generated due to the voltage imbalance between the battery racks 310 connected in parallel, and the inrush current causes a current exceeding the capacity of the device to flow into the device, which may destroy the device or cause a fire. have.

In particular, when the battery is implemented as a lithium ion battery, as shown in FIG. 4, since the dynamic voltage and the open circuit voltage (OCV) of the charge / discharge state are different, the battery rack 310 is paralleled. When connected, inrush current will be generated.

Such inrush current may occur when the battery rack 310 is replaced or restarted in addition to the first connection of the battery rack 310. In order to prevent such inrush current, the battery racks 310 to be connected in parallel can be individually charged and connected after the voltages of all the battery racks 310 become equal. It takes a long time to replace, and in the case of a large battery energy storage system, the system down time may be long, resulting in a large economic loss.

Accordingly, the present invention pre-charges the batteries included in the trays 320a to 320n during the time interval before the battery energy storage system 100 reaches the normal state through the initial charging unit 340. Minimizing the voltage difference between the battery rack 310 to prevent the generation of inrush current.

To this end, the initial charging unit 340 is composed of a first resistor 342 and a second switch 344.

As shown in FIG. 3, the first resistor 342 is connected in series to the trays 320a to 320n, and the second switch 344 is connected in series to the first resistor 342 to provide the first resistor 342. ) And the power management device 220.

In detail, the second switch 344 is maintained in an on state for a time interval before the battery energy storage system 100 reaches a normal state, such that the second resistor 342 and the power management device 220 are maintained. Connect the batteries included in the trays 320a to 320n to be initially charged.

Thereafter, when the battery energy storage system 100 reaches the normal state, the second switch 344 is turned off.

In the above-described embodiment, when one or more battery racks 310 are connected to the power management device 220, the battery rack 310 having the lowest open circuit voltage (OCV) among the battery racks 310 is the power management device. It is preferred to connect to 220 first.

In the above-described embodiment, it has been described that the inrush current is prevented by using an analog method of adding a circuit configuration to the battery rack 310.

However, in the modified embodiment, in order to prevent generation of inrush current digitally, when N battery racks 310 are connected in parallel, each battery rack controller (not shown) is connected to the voltage of the battery rack 310. After monitoring, the battery rack 310 having the lowest voltage may be sequentially connected to the power management device 220.

In this case, according to the priority, the voltage of the battery rack 310 is in the dynamic voltage (DV) and the open circuit voltage (OCV) state, so the system design the voltage deviation between the state of charge (SOC) or the dynamic voltage and the open circuit voltage. It should be measured and reflected in the control.

For example, when the first battery rack of SOC 70% -3.8V and the second battery rack of SOC 55% -3.2V are connected in parallel, an inrush current is generated due to voltage imbalance. To prevent this, the second battery rack is first connected to the power management device 220 and then charged with energy. At this time, the controller monitors the SOC and the voltage of the first battery rack. As a result of monitoring, when the voltage of the first battery rack and the voltage of the second battery rack are the same, the first battery rack is connected to the power management device 220 in consideration of the voltage deviation between the dynamic voltage and the open circuit voltage which have been previously data-formed. do.

In the above-described embodiment, the inrush current is prevented by using any one of digital and analog methods. However, in the modified embodiment, both of these methods may be applied to prevent the inrush current.

For example, the battery racks 310 of which the voltage difference is smaller than the reference value of the battery racks 310 are controlled using a digital method, and the battery racks of which the voltage difference of the battery racks 310 are larger than the reference value may be controlled in an analog manner. Can be.

That is, the battery racks 310 having a larger voltage difference than the reference value of the battery racks 310 are simultaneously connected to the power management device 220, but the initial charging unit 340 is first connected to minimize the inrush current, the battery rack ( Battery racks 310 of which the voltage difference is smaller than the reference value among the 310 is to be sequentially connected to the power management device 220 from the battery rack 310 having a low voltage, SOC (state of charge) or dynamic voltage and open circuit The voltage deviation between voltages is measured and reflected in the control.

Referring back to FIG. 2, the surge voltage prevention unit 350 serves to suppress the generation of surge voltage according to the operation of the initial charging unit 340.

The reason why the battery energy storage system 100 according to the present invention includes the surge voltage preventing part 350 is that when the second switch 344 included in the initial charging part 340 is turned on and off, as shown in FIG. 5A. This surge voltage or communication noise occurs because a surge voltage 510 is generated or noise 520 occurs during communication between battery rack controllers (not shown) controlling each battery rack 310 as shown in FIG. 5B. To minimize this.

In an exemplary embodiment, the surge voltage protection unit 350 may include a Y-capacitor circuit connected to the first electrode terminal P and the second electrode terminal N of the trays 320a to 320n. Can be.

To this end, the surge voltage protection unit 350 according to the first embodiment of the present invention, as shown in Figure 3a, one end is connected to the first electrode terminal (P) of the tray (320a ~ 320n) and the other end is grounded A first capacitor C1 connected to the node N1 and a second capacitor C2 connected at one end to the ground node N1 and connected to a second electrode terminal N of the trays 320a to 320n. It may include.

In this case, the first capacitor C1 and the second capacitor C2 have the same capacitance value to equalize the potential between the first electrode terminal P and the ground and the potential between the second electrode terminal N and the ground. (C), the value of the capacitance of the first capacitor (C1) and the second capacitor (C2) in order to increase the rate of absorption of the surge voltage generated instantaneously is a smoothing capacitor included in the power management device 220 It may be less than the capacitance value of.

In one embodiment, the capacitance value C of the first or second capacitors C1 and C2 may be determined using Equation 1 below.

In Equation 1, C denotes capacitance values of the first or second capacitors C1 and C2, I denotes a leakage current in the first or second capacitors C1 and C2, and E denotes a battery rack. Denotes a voltage of f, and denotes a switching frequency of the inverter included in the power management device 220. In this case, the leakage currents in the first and second capacitors C1 and C2 may be predetermined within a range of 10 mA.

As shown in FIG. 3B, the surge voltage preventing unit 350 according to the second embodiment of the present invention is connected to the first capacitor C1, the second capacitor C2, and the first capacitor C1 in parallel. The second resistor R1 and a third resistor R2 connected in parallel to the second capacitor C2 may be included.

In this case, the second resistor R1 and the third resistor R2 have the same resistance value in order to equalize the potential between the first electrode terminal P and the ground and the potential between the second electrode terminal N and the ground. The resistance value may be several hundred KΩ to several MΩ. Here, determining the values of the second resistor R1 and the third resistor R2 as a large resistor value determines the resistance of the second resistor R1 and the third resistor R2 as a small value. This is to prevent this because the natural discharge of the battery occurs.

In an exemplary embodiment, the resistance value R of the second or third resistors R1 and R2 may be determined using Equation 2 below.

In Equation 2, R denotes a resistance value of the second or third resistors R1 and R2, t denotes a unit time for measuring the battery discharge rate, and a denotes a voltage of a battery rack. b denotes a rated current capable of charging and discharging the capacity of the battery rack during a unit time, and c denotes a discharge rate of the battery. In this case, t may be a value in units of time, and the battery discharge rate may be a value in units of%.

As described above, since the battery rack 310 according to the present invention includes the surge voltage preventing unit 350, as shown in FIG. 6A, the generation of the surge voltage due to the on / off of the second switch 344 is suppressed. It can be seen that the noise generated during communication between the battery rack controllers is also reduced 620 as shown in FIG. 6B.

In addition, in the present invention, the surge voltage protection unit 350 included in the battery rack 310 has the same potential between the first electrode terminal P and the ground as the potential between the second electrode terminal N and the ground. By doing so, it is possible to improve the potential imbalance at both ends of the smoothing capacitor included in the power management device 220.

Referring back to FIG. 2, the power management device 220 performs a role of associating the battery management device 210 with a system (not shown). More specifically, the power management device 220 charges surplus energy of the system to one or more battery racks 310 included in the battery management device 210 or provides the system with energy stored in the one or more battery racks 310. It plays a role.

Hereinafter, a power management apparatus according to the present invention will be briefly described with reference to FIG. 7.

7 is a diagram illustrating an electrical configuration of a power management device according to an embodiment of the present invention.

As shown in FIG. 7, the power management device 220 according to the present invention includes a first breaker 710, a transformer 720, and one or more power converting units (PCUs) 730. .

First, the first breaker 710 serves to block an accident current from flowing into the system 700 or flowing into the power conversion module 730 when an accident occurs.

Next, the transformer 720 reduces the AC voltage of the system 700 to a predetermined value and supplies it to the power conversion module 730, or boosts the AC voltage output from the power conversion module 730 to a predetermined value. Serves as a system (700).

Next, the power conversion module 730 converts the alternating current into direct current to provide to the battery management device 210, or converts the direct current provided from the battery management device 210 into alternating current and outputs it to the transformer 720.

The power conversion module 730 includes a second breaker 731, a filter 733, an inverter 735, a smoothing capacitor 737, and a third switch 739.

First, the second circuit breaker 731 serves to block an accident current from flowing into the system 700 or flowing into the power conversion module 730 when an accident occurs.

The filter 733 reduces the harmonics of the AC voltage reduced through the transformer 720 or reduces the harmonics of the AC voltage output from the inverter 735.

In FIG. 7, the filter 733 is illustrated as being of an LCL type, but this is just an example.

The inverter 735 converts an AC voltage output from the filter 733 into a DC voltage, or converts a DC voltage supplied from the battery management device 210 into an AC voltage.

The smoothing capacitor 737 smoothes the DC voltage input from the battery management device 210 to the inverter 735 or the DC voltage output from the inverter 735. When the voltage of the smoothing capacitor 737 is charged in advance, an inrush current may be prevented from occurring when the battery management device 210 is connected to the power management device 220.

If the smoothing capacitor 737 is not charged when the battery management device 210 is connected to the power management device 220, an inrush current may be generated and the device may be destroyed or a fire may be generated.

The third switch 739 serves to connect the battery management device 210 to the power management device 220.

Referring back to FIG. 2, the controller 230 determines whether one or more batteries included in the battery management device 210 are charged or discharged, and the battery management device 210 and the power management device ( 220 to control the operation.

Those skilled in the art to which the present invention pertains will understand that the above-described present invention can be implemented in other specific forms without changing the technical spirit or essential features.

Therefore, it is to be understood that the embodiments described above are exemplary in all respects and not restrictive. The scope of the present invention is defined by the appended claims rather than the detailed description and all changes or modifications derived from the meaning and scope of the claims and their equivalents are to be construed as being included within the scope of the present invention do.

100: battery energy storage system 110: energy management system
120: global monitoring system 210: battery management device
220: power management device 230: controller
310: Battery Rack 320a to 320n: Tray
330: First switch 340: Initial charging unit
342: second switch 344: first resistor
350: surge voltage suppressor

Claims (13)

A tray composed of one or more batteries;
A first switch connecting the tray to a Power Conditioning System (PCS) for charging and discharging the one or more batteries;
An initial charging unit which operates before the first switch is turned on to prevent inrush current generation by initial charging the one or more batteries; And
And a surge voltage prevention unit for absorbing a surge voltage generated by the operation of the initial charging unit through at least one capacitor to remove the surge voltage. The method of claim 1,
The surge voltage suppressor may include a first capacitor having one end connected to a first electrode terminal of the tray and the other end connected to a ground node, and one end connected to the ground node and another end connected to a second electrode terminal of the tray. Consists of a Y-capacitor circuit containing two capacitors,
The first capacitor and the second capacitor have the same capacitance value so that the first potential between the first electrode terminal and the ground node and the second potential between the second electrode terminal and the ground node are equal. Battery management device. The method of claim 2,
The capacitance value of the first or second capacitor is

Calculated using
I denotes a leakage current in the first or second capacitor, E denotes a voltage of a battery rack configured by connecting a plurality of trays, and f denotes a switching frequency of an inverter included in the power management device. Battery management device characterized in that. The method of claim 2,
The surge voltage preventing unit further includes a first resistor connected in parallel to the first capacitor and a second resistor connected in parallel to the second capacitor.
And the first and second resistors have the same resistance value so that the first potential and the second potential become the same. 5. The method of claim 4,
The resistance value of the first resistor or the second resistor is represented by an equation

Calculated using
R denotes a resistance value of the first resistor or the second resistor, t denotes a unit time for measuring the discharge rate of the battery, a denotes a voltage of a battery rack configured by connecting a plurality of trays, and b denotes a The battery management device, characterized in that the rated current capable of charging and discharging the capacity of the battery rack for a unit time, c means the discharge rate of the battery. The method of claim 1,
The at least one capacitor, characterized in that the battery management device having a capacitance value less than the capacitance value of the smoothing capacitor included in the power management device so that the absorption rate of the surge voltage is increased. The method of claim 1,
The initial charging unit,
A third resistor connected in series with the tray; And
And a second switch connected in series with the third resistor to electrically connect the third resistor and the power management device. The method of claim 7, wherein
The second switch is turned on until a battery energy storage system (BESS) reaches a steady state so that the at least one battery is initially charged through a connection between the third resistor and the power management device. And off when the battery energy storage system reaches a steady state. The method of claim 1,
The first switch is turned off until the battery energy storage system reaches a normal state, and is turned on when the battery energy storage system reaches the normal state to connect the tray to the power management device. Battery management device. A battery management device including one or more battery racks charged with surplus energy provided from a system; And
And a power management device configured to charge the surplus energy in the at least one battery rack, discharge the energy charged in the at least one battery rack, and provide the surplus energy to the system.
The battery rack,
A tray consisting of one or more batteries;
An initial charging unit configured to initially charge the one or more batteries by connecting the tray to the power management device during a time period before the battery energy storage system reaches a normal state; And
And a surge voltage protection unit absorbing a surge voltage generated by the operation of the initial charging unit through at least one capacitor. The method of claim 10,
The battery management device includes:
And a first switch that is turned on when the battery energy storage system reaches a normal state and connects the tray to the power management device. The method of claim 10,
The surge voltage prevention unit,
A first capacitor having one end connected to a first electrode terminal of the tray and the other end connected to a ground node;
A first resistor connected in parallel to the first capacitor;
A second capacitor having one end connected to the ground node and the other end connected to a second electrode terminal of the tray; And
And a second resistor connected in parallel to said second capacitor. The method of claim 10,
The initial charging unit,
A third resistor connected in series with the tray; And
And a second switch that is turned on for a time period before the battery energy storage system reaches a steady state to electrically connect the third resistor and the power management device.

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