KR20150078009A - Battery Energy Storage System and Method for Controlling Battery Energy Storage System - Google Patents

Abstract

A battery energy storage system according to an embodiment of the present invention is able to prevent a circulating current from occurring among a plurality of power converters when operating in an independent operating mode. The battery energy storage system includes: N power converters which supply power provided from a system and operates in a first operating mode supplying the power provided from a battery management apparatus in connection to the system and operates in a second operating mode directly supplying the power provided from the battery management apparatus in non-connection to the system; and a control unit which calculates sharing energy of the power converters based on charging or discharging power of the power converters and the number of the power converters when the power converters operate in the second operating mode. The N power converters include: a current control type power converter controlling a first output voltage to have the first output current applied to load based on the sharing energy when operating in the second operating mode; and a voltage control type power converter which controls a second output voltage to have a constant voltage applied to the load when operating in the second operating mode but reduces the second output voltage in stages if a second output current becomes greater than or equal to a threshold value.

Description

[0001] The present invention relates to a battery energy storage system and a battery energy storage system,

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

The energy storage system (ESS) connects renewable energy such as wind power and solar power, which can not control the power generation output, to the existing power network, and charges or discharges energy according to the power consumption pattern.

Particularly, a battery energy storage system (BESS) using a secondary battery is used not only for stabilizing the voltage and frequency of the system but also in connection with a renewable energy generation system such as wind power or solar power, And stores the excess energy, discharges the energy stored in the battery when a peak load or a system fault occurs, supplies energy to the load, and attenuates the transient state when the system is restored.

1 is a block diagram schematically illustrating the configuration of a general battery energy storage system.

As shown in FIG. 1, a typical battery energy storage system 10 includes a power management device 20 and a battery management device 30.

The power management system (PCS) 20 supplies power to the system 40 using energy stored in a plurality of battery racks 31a to 31n included in the battery management device 30, And charges the plurality of battery racks 31a to 31n using the power supplied from the battery 40. [ To this end, the power management device 20 converts the DC power supplied from the battery management device 30 into AC power, supplies the AC power to the system 40, converts the AC power supplied from the system 40 to DC power And a power conversion unit (PCU) 21 for supplying the power to the battery management device 30. 1, the power management apparatus 20 includes a plurality of power conversion units 21a to 21n, and a plurality of power conversion units 21a to 21n are connected in parallel to each other A large-capacity battery energy storage system can be realized.

The battery management system (BCS) 30 stores the power supplied from the system 40 in the plurality of battery racks 31a to 31n under the control of the power management apparatus 20, 31a to 31n are supplied to the system 40 through the power management device 20. [

The battery energy storage system 10 having the above-described configuration can be applied to a case where an abnormality occurs in the system 40 and the battery energy storage system 10 is separated from the system 40, When operating in conjunction with new and renewable energy sources in the mountains, it should operate as an independent energy source and supply stable power to the load. In this way, the operation of the battery energy storage system without being connected to the system is referred to as the independent operation mode.

When the battery energy storage system 10 operates in the independent operation mode, the power conversion unit 21 included in the power management device 20 of the battery energy storage system 10 is supplied with a voltage And operates as an energy source. In this case, when the plurality of power conversion units 21a to 21n are connected in parallel, load sharing control between the power conversion units 21a to 21n is required. To control the load sharing, each of the power conversion units 21a to 21n Is operated as a voltage-type energy source to perform voltage control, an error occurs in the output voltage due to problems such as sensing error, control error, synchronization between the power conversion units, and the like, .

It is an object of the present invention to provide a battery energy storage system and a battery energy storage system control method capable of preventing cyclic current generation between a plurality of power conversion units when operating in an independent operation mode, It is a technical task.

It is another object of the present invention to provide a battery energy storage system and a battery energy storage system control method capable of preventing an overcurrent due to a load imbalance between power conversion units in a communication delay time in a process of calculating a shared power amount among power conversion units, We will do it.

According to an aspect of the present invention, there is provided a battery energy storage system comprising: a battery management system that provides power to a battery management apparatus in a system when a grid is connected, N power conversion units operating in a mode and operating in a second operation mode in which power supplied from the battery management apparatus is directly supplied to the load in the system non-learning mode; And a control unit for calculating a shared power amount of the power conversion unit based on a charge or discharge power amount of the power conversion unit and a number of the power conversion units when the power conversion unit operates in a second operation mode, A current control type power conversion unit for controlling a first output voltage so that a first output current is applied to the load based on the shared power amount when operating in a second operation mode; And the second output voltage is controlled so that a constant voltage is supplied to the load in the second operation mode. When the second output current is equal to or more than the threshold value for a time before the current controlled power converter operates, And a voltage-controlled-type power conversion unit for reducing the voltage-controlled power conversion unit stepwise.

According to another aspect of the present invention, there is provided a control method of a battery energy management system having N power conversion units including a current control type power conversion unit and a voltage control type power conversion unit, Calculating a shared power amount of the current control type power conversion unit; Transmitting the shared power amount to the current controlled power converter; Controlled power converter such that when the output current of the voltage controlled power converter reaches a threshold value or more during a time before the current controlled power converter operates based on the shareable amount of power, the output voltage of the voltage controlled power converter is step- And controlling a negative output voltage.

According to the present invention, when the battery energy storage system operates in the independent operation mode, the power conversion unit of one of the plurality of power conversion units operates as a voltage-type energy source and the remaining power conversion units operate as a current- It is possible to prevent the circulating current from being generated between the plurality of power conversion units and to supply power to the load stably.

In addition, according to the present invention, even if a load imbalance occurs between the power conversion units due to a communication delay in the process of calculating the shared power amount among the power conversion units, it is possible to prevent the output current of the power conversion unit operating as a voltage- , It is possible to prevent the battery energy storage system from stopping or malfunctioning in advance, thereby enabling the power to be continuously supplied to the load.

 In addition, according to the present invention, it is possible to prevent derating due to the occurrence of an overcurrent of the power conversion unit or design of a system over capacity, thereby reducing the manufacturing cost of the battery energy storage system and securing price competitiveness.

1 is a block diagram schematically illustrating the configuration of a conventional battery energy storage system;
2 is a block diagram schematically illustrating the configuration of a battery energy storage system according to an embodiment of the present invention;
FIG. 3A is a graph showing the output current waveforms of the current-controlled power converter and the voltage-controlled power converter when no communication delay occurs. FIG.
FIG. 3B is a graph showing output current waveforms of the current-controlled power converter and the voltage-controlled power converter when a communication delay occurs. FIG.
4 is a block diagram schematically showing a configuration of a voltage-controlled power converter according to an embodiment of the present invention.
5 is a graph showing an output voltage reduction amount of the voltage controlled power converter calculated by the reduction amount calculating unit shown in FIG.
6 is a graph showing output current waveforms of a current controlled power converter and a voltage controlled power converter according to the present invention when a communication delay occurs.
FIG. 7 is a block diagram schematically showing the configuration of a current controlled power converter according to an embodiment of the present invention; FIG.
8 is a flowchart illustrating a method of controlling a battery energy storage system 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.

The meaning of the terms described herein should be understood as follows.

The word " first, "" second," and the like, used to distinguish one element from another, are to be understood to include plural representations unless the context clearly dictates otherwise. The scope of the right should not be limited by these terms.

It should be understood that the terms "comprises" or "having" does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

It should be understood that the term "at least one" includes all possible combinations from one or more related items. For example, the meaning of "at least one of the first item, the second item and the third item" means not only the first item, the second item or the third item, but also the second item and the second item among the first item, Means any combination of items that can be presented from more than one.

<Battery Energy Storage System>

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

The battery energy storage system 200 according to an exemplary embodiment of the present invention shown in FIG. 2 includes a grid-connected operation mode for storing electric power provided from a system in a system when the system is connected to the system, And a stand-alone operation mode in which power stored in the battery and the system is supplied to the load as a load. Here, the situation where the battery energy storage system 200 is not connected to the system may be a situation where the system is disconnected from the system due to an abnormality in the system, or a situation where the existing energy network 200 is disconnected from the system It refers to the situation that operates in conjunction with renewable energy sources.

Hereinafter, the configuration of the battery energy storage system 200 will be described on the assumption that the battery energy storage system 200 operates in the independent operation mode for convenience of explanation.

The battery energy storage system 200 includes a battery management device 210 and a power management device 220, as shown in FIG. 2, the battery energy storage system 200 includes one battery management device 210. However, in the modified embodiment, the battery energy storage system 200 may include a single battery management system And may include a plurality of battery management apparatuses 310.

First, a battery management system (BCS) 210 stores electric power supplied from a renewable energy source (not shown) such as wind power or solar light during charging, and supplies the stored electric power to a load do.

The battery management device 210 includes a plurality of battery racks 212a to 212n, as shown in FIG. 2, in addition to the battery racks 212a to 212n, the battery management device 210 includes a control device for controlling the battery racks 212a to 212n, a fire control module for controlling the occurrence of fire in the battery management device 210, And a climate control module for controlling the temperature in the battery management device 210. [

The plurality of battery racks 212a to 212n includes a battery module (not shown) in which a plurality of batteries (not shown) connected in series are packed. The battery modules are stacked in a battery rack 212a to 212n . The plurality of battery racks 212a to 212n store power in a plurality of batteries packed in the battery module in accordance with the charge command of the power management unit 220 and discharge the power stored in the plurality of batteries according to the discharge command do.

In addition, although not shown, the battery racks 212a to 212n further include a fan, an initial charge module, a control module, and a power supply module.

The fan is for controlling the temperature of the battery module, and may be provided for each of a plurality of battery modules or may be separately provided for each battery module.

The initial charging module may be configured such that when the battery racks 212a to 212n or the battery module are newly connected in the battery management apparatus 210 or a voltage unbalance occurs between the battery racks 212a to 222n during operation of the battery management apparatus 210, And prevents an inrush current that may be generated due to a voltage difference between the first and second transistors 212a to 212n. The inrush current is generated due to a voltage unbalance between the battery racks 212a to 212n connected in parallel. As a result of this inrush current, a current exceeding the capacity of the device flows to the device, have. Accordingly, in the present invention, during the time interval before the battery energy storage system 200 reaches the normal state through the initial charging module, each battery included in the plurality of battery modules is precharged (precharged) Thereby minimizing the voltage difference between the first and second switches 212a to 212n, thereby preventing the occurrence of an inrush current.

The control module is included in each of the battery racks 212a to 212n to monitor the states of the plurality of battery modules included in the battery racks 212a to 212n and to control charging and discharging operations of the plurality of battery modules. In one embodiment, the control module monitors at least one of voltage, current, SOC, and temperature of each battery included in the plurality of battery modules to monitor the status of the plurality of battery modules.

The power management device 220 stores the power provided from the renewable energy source in the battery management device 210 or supplies the power stored in the battery management device 210 to the load. More specifically, the power management apparatus 220 is configured to charge one or more battery racks 212a to 212n included in the battery management apparatus 210 with power supplied from a renewable energy source, or to charge one or more battery racks 212a to 212n ) To the load.

To this end, the power management apparatus 220 according to the present invention includes a control unit 221 and a plurality of power conversion units (PCUs) 222a to 222n as shown in FIG. As shown in FIG. 2, the power conversion units 222a to 222n include a voltage control type power conversion unit 222a for controlling the output voltage to supply a constant voltage to the load, And a plurality of current control type power conversion units 222b to 222n for controlling the output voltage so as to control the output voltage. That is, when the power management apparatus 220 includes N power converters 222a through 222n, the power converters 222a through 222n are each provided with one voltage-controlled power converter 222a and N-1 current- And a power conversion unit. Although not shown in FIG. 2, the power management device 220 may further include a transformer for boosting the AC voltage output from each of the power conversion units 222a to 222n to a predetermined value and supplying the AC voltage to the load.

First, the control unit 221 receives information on the amount of charged electric power or the amount of discharged electric power of the electric power conversion units 222a to 222n from the respective electric power conversion units 222a to 222n, Controlled power conversion sections 222b to 222n based on the number of the power control sections 222a to 222n.

In one embodiment, the control unit 221 calculates the sum of the charging power amount or the discharging power amount of each of the power conversion units 222a to 222n received from the power conversion units 222a to 222n, To the divided electric power amounts of the current controlled power converters 222b to 222n. In this case, the charging power amount is added up to a positive value, and the discharge power amount is added to a negative value.

The role of actively sharing the output according to the amount of power required from the load is performed by the current controlled power converters 222b to 222n. The control unit 221 transmits the calculated shareable power amount to each of the current controlled power converters 222b to 222n so that each of the current controlled power converters 222b to 222n can output the shared power amount calculated by the control unit 221 .

In the above-described embodiment, the charging power amount or the discharge power amount is a concept including not only active power but also reactive power. Accordingly, the control unit 221 calculates the amount of active power and the amount of reactive power that the current control type power conversion units 222b to 222n should bear, respectively, and transmits them to the current control type power conversion units 222b to 222n.

Next, the power conversion units 222a to 222n convert the AC power into DC power and provide it to the battery management apparatus 210, or convert the DC power supplied from the battery management apparatus 210 to AC power and supply The plurality of power conversion units 222a to 222n may be connected in parallel to each other for realizing the large capacity battery energy storage system 200. [

As described above, the power conversion units 222a to 222n include one voltage control type power conversion unit 222a for controlling the output voltage so as to supply a constant voltage to the load, And N-1 current controlled power converters 222b to 222n for controlling the voltage.

First, the voltage-controlled power converter 222a performs voltage control such that an output voltage having a constant frequency and voltage magnitude is output regardless of the amount of power required in the load through proportional integral (PI) control. In particular, in the case where the battery energy storage system 200 operates in the independent operation mode, the voltage-controlled power converter 222a replaces the role of the system, so that the voltage-controlled power converter 222a generates an arbitrary phase angle And the output voltage phase angle of the voltage-controlled power converter 222a is determined by?

Next, the current-controlled power conversion sections 222b to 222n receive the shared power amount of each of the current control type power conversion sections 222b to 222n from the control section 221 and, based on the received burdened power amount, (222b to 222n).

The current control type power converters 222b to 222n perform current control through proportional integral (PI) control so that the output currents output from the current control type power converters 222b to 222n can follow the current command value.

The current-controlled power converters 222b to 222n extract the output voltage phase angle of the voltage-controlled power converter 222a and perform synchronization with the voltage-controlled power converter 222a through a PLL (Phase Locked Loop).

As described above, according to the present invention, the power conversion unit 222a of any one of the plurality of power conversion units 222a to 222n is controlled by the voltage control type power conversion unit 222, which supplies an output voltage having a constant voltage and frequency, And the remaining power conversion units 222b to 222n operate as the current control type power conversion units 222b to 222n for allowing the output current corresponding to the current command value calculated by the control unit 221 to be supplied to the load So that cyclic current generation between the power conversion units 222a to 222n can be prevented as well as load equalization sharing control is performed simultaneously so that power can be supplied to the loads uniformly.

However, in this case, in the process of each of the power conversion units 222a to 222n transmitting the charging power amount or the discharging power amount to the control unit 221, the control unit 221 calculates the sharing power amount of the current control type power conversion units 222b to 222n There is a problem in that a communication delay may occur in the course of transmitting the sharing power amount to the current control type power converters 222b to 222n and the overcurrent may be generated at the moment when the load is inputted.

More specifically, a process in which each of the power conversion units 222a to 222n transmits the charging power amount or the discharging power amount to the control unit 221, and the control unit 221 calculates the sharing power amount of the current control type power conversion units 222b to 222n 3A, when the load is applied as shown in FIG. 3A, the current-controlled power converters 222b to 222n operate in accordance with the current command value, and the shared power amount calculated by the controller 221 The overcurrent does not occur in the voltage-controlled power converter 222a.

However, in the process of transmitting the amount of charged power or the amount of discharged power to each of the power conversion units 222a to 222n to the control unit 221 and the process of calculating the shared power amount of the current controlled power conversion units 222b to 222n 3B, when the current control type power conversion units 222b to 222n do not receive the current command value at the time when the load is turned on, the current control type power conversion units 222b to 222n It can not operate according to the current command value. Therefore, since the voltage-controlled power converter 222a has to cover all the amount of power required in the load for the period of time until the current-controlled power converters 222b to 222n receive the current command value and normally operate, The battery energy storage system 200 stops operation in order to protect the system, thereby causing a power failure.

In order to solve the above-described problems, the voltage-controlled power converter 222a according to the present invention controls the current-controlled power converters 222b to 222n to operate in accordance with the current command value, The first output current from the voltage controlled power converter 222a is gradually decreased when the first output current exceeds the threshold value by monitoring the first output current from the first output current 222a, .

Hereinafter, the configurations of the voltage-controlled power converter 222a and the current-controlled power converters 222b to 222n according to the present invention will be described more specifically with reference to FIG. 4 to FIG.

4 is a block diagram schematically showing the configuration of a voltage-controlled power converter according to an embodiment of the present invention.

As shown in FIG. 4, the voltage-controlled power converter 220a includes a voltage controller 410 and a first power conversion module 420.

The voltage controller 410 controls the first output voltage output from the first power conversion module 420 so that a voltage having a predetermined frequency and magnitude can be supplied to the load. Particularly, the voltage controller 410 according to the present invention controls the first voltage conversion module 420 and the second voltage conversion module 420 during the transient state period before the current controlled power converters 222b to 222n operate according to the current command value, As a result of the monitoring, if the first output current increases beyond the threshold value, the first output voltage outputted from the first voltage conversion module 420 is gradually decreased.

To this end, the voltage controller 410 includes a PI controller 412, a reduction amount calculation unit 414, and a PWM control unit 416 as shown in FIG.

First, the PI controller 412 compares the voltage command value Vref to be supplied to the load with the first output voltage Vfbk output from the first power conversion module 420 and fed back, and outputs the first output voltage Vfbk as a voltage command value And generates a gating reference voltage Vgref to follow the reference voltage Vref.

When the first output current outputted from the first power conversion module 420 is equal to or more than the threshold value during the transient state period before the current controlled power converters 222b through 222n operate according to the current command value And calculates a reduction amount of the first output voltage outputted from the first voltage conversion module 420. [

In one embodiment, if the first output current output from the first power conversion module 420 is greater than or equal to the first threshold, the decrease amount calculator 414 calculates the decrease amount of the first output current during the period until the first output current reaches the second threshold 1 &lt; / RTI &gt; voltage conversion module 420. The first output voltage &lt; RTI ID = 0.0 &gt; This is because, since there is a control margin until a fault occurs in the battery energy storage system 200, the decrease amount of the first output voltage is initially set to a small value, and as the first output current approaches the rated current, 1 &lt; / RTI &gt; output voltage.

If the first output current outputted from the first power conversion module 420 is equal to or greater than the second threshold value, the decrease amount calculation unit 414 calculates the decrease amount of the first output current until the first output current reaches the limit current value of the battery energy storage system 200 The amount of decrease of the first output voltage output from the first voltage conversion module 420 is linearly increased.

In one embodiment, since the first output voltage can be reduced by reducing the gating reference voltage Vgref generated by the PI controller 412, the decrease amount calculating section 414 calculates the decrease amount of the first output voltage It can be calculated by substituting the amount of reduction of the gating reference voltage Vgref.

More specifically, the decrease amount calculation unit 414 monitors the first output current output from the first voltage conversion module 420, and when the first output current is greater than or equal to the first threshold, The amount of decrease in the gating reference voltage Vgref is calculated using the following equation (1).

Where a is a predetermined weight (e.g., a is 0.1), x is the value of the first output current currently being output from the first voltage conversion module, and N is the number of the power conversion units.

In one embodiment, the first threshold is set to a value that is the value of the rated current of the battery energy storage system 200 divided by the number N of power converters, Can be set to the value of the rated current.

In addition, the decrease amount calculating unit 414 calculates the decrease amount of the battery output voltage by using the following equation (2) during the period until the first output current becomes the limit current value of the battery energy storage system 200 when the first output current is equal to or greater than the second threshold value And calculates a reduction amount of the gating reference voltage Vgref.

X is the value of the rated current of the battery energy storage system 200 and x2 is the value of the rated current of the battery energy storage system 200. In the above equation, x is the value of the first output current output from the first voltage conversion module 420, Y1 is the grid permissible voltage variation value (e.g., 12%), and y2 is the limit voltage variation value (e.g., 20%) of the battery energy storage system.

Here, the value of the limit current of the battery energy storage system 200 means a value of the output current at which the operation of the battery energy storage system 200 should be stopped, Means a voltage variation value for avoiding occurrence of a fault in the energy storage system 200. [

The relationship between the amount of reduction of the first output voltage (or the gating reference voltage) calculated through the voltage controller 410 and the first output current is shown in FIG. 5 as a graph.

5, the voltage controller 410 does not reduce the first output voltage if the first output current is less than the first threshold (100% / N), and does not decrease the first output voltage when the first output current is greater than or equal to the first threshold The reduction amount of the first output voltage is exponentially increased within the range of the grid permissible voltage variation value (12%) until the first output current reaches the first threshold value (100% of the rated current), and the first output current (20%) of the battery energy storage system 200 until the first output current reaches the limit current value (120% of the energizing current) when the first output current is equal to or greater than the second threshold value As shown in Fig.

As described above, in the present invention, during the transient state period before the current-controlled power converters 222b to 222n operate according to the current command value, the voltage controller 410 controls the voltage The first output voltage outputted from the first voltage conversion module 420 is stepped down when the output current of the first voltage conversion module 420 is increased to the threshold value or more. Therefore, even if the rated load is inputted in step as shown in FIG. 6, The output current of the switching regulator 222a is not excessively increased, and the system is operated stably.

Referring again to FIG. 4, the PWM control unit 416 receives the gating reference voltage Vgref, modulates it into a PWM signal, and supplies the modulated PWM signal to the inverter 422 of the first power conversion module 420.

The first power conversion module 420 converts the DC power supplied from the battery management device into AC power and supplies the AC power to the load. The AC power supplied from the renewable energy source is converted into DC power and supplied to the battery management device.

To this end, the first power conversion module 420 includes an inverter 422 and a filter 424 as shown in FIG.

The inverter 422 converts the DC power supplied from the battery management device into AC power. In particular, the inverter 422 according to the present invention operates according to the gating reference voltage input from the voltage controller 410, thereby outputting a constant voltage.

The filter 424 reduces harmonics of the alternating voltage output from the inverter 422. Although the filter 424 is shown as being of the LCL type in Fig. 4, this is only an example, and other configurations are possible.

4, the first power conversion module 420 may further include a breaker, a smoothing capacitor, an initial charge module, and a switch.

The circuit breaker serves to prevent the fault current from flowing into the first power conversion module 420 when an accident occurs. In addition, the circuit breaker serves to connect or disconnect the first power conversion module 420 to the load.

The smoothing capacitor performs a role of smoothing the DC voltage input from the battery management device 210 to the inverter 422 or the DC voltage output from the inverter 422. The voltage of the smoothing capacitor needs to be pre-charged to prevent an inrush current from occurring when the battery management device 210 is connected to the power management device 220.

The initial charging module prevents generation of an inrush current when the smoothing capacitor is not charged when the battery management device 210 is connected to the power management device 220, thereby preventing the device from being destroyed or generating a fire.

The switch performs a role of connecting the battery management device 210 to the power management device 220.

Hereinafter, the configuration of the current controlled power converter according to the present invention will be described with reference to FIG.

FIG. 7 is a block diagram schematically illustrating a configuration of a current controlled power converter according to an embodiment of the present invention. Referring to FIG.

As shown in FIG. 7, the voltage-controlled power converters 220b to 220n include a current controller 710 and a second power conversion module 720.

The current controller 710 controls the second output voltage outputted from the second voltage conversion module 720 so that the second output current corresponding to the current command value is applied to the load in the second voltage conversion module 720.

To this end, the current controller 710 includes a current command value calculation unit 712, a PI controller 714, and a PWM control unit 716.

The current command value calculation unit 712 receives the shared power amount from the control unit 210 and divides the shared power amount by the value of the second output voltage outputted from the second voltage conversion module 720 to calculate the current command value.

The PI controller 714 compares the current command value Iref with the second output current Ifbk that is output and fed back from the second power conversion module 420 so that the second output current Ifbk follows the current command value Iref To generate a gating reference voltage Vgref.

The current controller 710 controls the second output voltage outputted from the second power conversion module 720 by controlling the gating reference voltage Vgref of the inverter 722 included in the second power conversion module 720 .

The PWM control unit 716 receives the gating reference voltage Vgref, modulates it into a PWM signal, and supplies it to the inverter 722 of the second power conversion module 720.

The second power conversion module 720 converts the DC power supplied from the battery management device into AC power and supplies the AC power to the load. The AC power supplied from the renewable energy source is converted into DC power and supplied to the battery management device. The function and configuration of the second power conversion module 720 are the same as those of the first power conversion module 420, and thus a detailed description thereof will be omitted.

<Control Method of Battery Energy Storage System>

Hereinafter, a method of controlling the battery energy storage system according to the present invention will be described with reference to FIG.

8 is a flowchart illustrating a method of controlling a battery energy storage system according to an embodiment of the present invention. The control method shown in Fig. 8 can be applied to a battery energy storage system having a configuration as shown in Fig.

First, the control unit calculates the shared power amount to be borne by the current-controlled power conversion unit (S800). In one embodiment, the shared power amount of the power conversion section can be calculated by dividing the value obtained by summing the amount of charge electric power or the amount of electric power received from each power conversion section by the number of power conversion sections.

Then, the control unit transmits the calculated shared power amount to the current controlled power converter so that the current controlled power converter can calculate the current command value (S810).

Then, it is determined whether the first output current, which is the output current of the voltage controlled power converter, is equal to or greater than the first threshold value (S820). If the first output current is smaller than the first threshold value, (S830).

If it is determined in step S820 that the first output current is equal to or greater than the first threshold value, it is determined whether the first output current is equal to or greater than the second threshold value in step S840. If the first output current is less than the second threshold value, The first output voltage is decreased by the amount of reduction calculated by Equation 1 (S850).

If it is determined in operation S840 that the first output current is greater than or equal to the second threshold value (S860), it is determined whether the first output current is equal to or greater than the limit current value of the battery energy storage system (S870), the first output voltage is decreased by a reduction amount calculated by Equation (2) within the limit voltage variation value range of the battery energy storage system.

If it is determined in operation S860 that the first output current is equal to or greater than the limit current value of the battery energy storage system, operation of the battery energy storage system is suspended (S880).

It is possible to reduce the first output voltage by reducing the gating reference voltage of the inverter included in the voltage controlled power converter in the above-described S850 and S870 by a reduction amount calculated by Equations (1) and (2).

The control method of the battery energy storage system may be implemented in a form of a program that can be performed using various computer means. The program for performing the control method of the battery energy storage system may be a hard disk, a CD-ROM, Readable recording medium such as a DVD, a ROM, a RAM, or a flash memory.

It will be understood by those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof.

It is therefore to be understood that the above-described embodiments are illustrative in all aspects 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.

200: battery energy storage system 210: battery management device
210a to 210n: battery rack 220: power management device
221: Control section 222a: Voltage control type power conversion section
222b to 222n: current control type power conversion unit
410: voltage controller 412, 714: PI controller
414: reduction amount calculating section 416, 716: PWM control section
420: first power conversion module 422, 722: inverter
424, 724: filter 710: current controller
712: Current command value calculation unit

Claims (13)

The system is operated in a first operation mode in which the power provided from the system is supplied to the battery management apparatus and the power provided from the battery management apparatus is supplied to the system when the system is connected and the power supplied from the battery management apparatus is directly supplied to the load N power conversion units operating in a second operation mode in which the first and second operation modes are activated; And
And a control unit for calculating a shared power amount of the power conversion unit based on a charge or discharge power amount of the power conversion unit and a number of the power conversion units when the power conversion unit operates in a second operation mode,
Wherein the N power converters comprise:
A current control type power converter for controlling a first output voltage so that a first output current is applied to a load based on the shared power amount when operating in a second operation mode; And
Controlling the second output voltage such that a constant voltage is supplied to the load in the second operation mode, and when the second output current exceeds the threshold value for a time before the current controlled power converter operates, And a voltage-controlled power converter for decreasing the voltage of the battery to a predetermined voltage. The method according to claim 1,
Wherein the current control type power conversion unit comprises:
A first voltage conversion module for converting the DC power supplied from the battery management device into AC power and supplying the AC power to the load;
Dividing the shared power amount by the value of the first output voltage outputted from the first voltage conversion module, and controlling the first output voltage to be applied to the load in the first voltage conversion module And a current controller for controlling the first output voltage. The method according to claim 1,
Wherein the voltage-controlled-
A second voltage conversion module that converts the DC power supplied from the battery management device into AC power and supplies the AC power to the load;
Wherein the second output voltage is increased by an exponential function when the second output current outputted from the second voltage conversion module is equal to or greater than a first threshold value, And a voltage controller for linearly increasing the amount of reduction of the second output voltage when the second threshold value is greater than a second threshold value. The method of claim 3,
Wherein the second voltage conversion module includes an inverter for converting DC power supplied from the battery management device into AC power,
Wherein the voltage controller adjusts the gating reference voltage of the inverter to reduce the second output voltage. The method of claim 3,
Wherein the voltage controller comprises:
Sets a value obtained by dividing a value of a rated current of the battery energy storage system by the number of the power conversion units to the first threshold value,
And sets the value of the rated current of the battery energy storage system to the second threshold value. The method of claim 3,
And when the second output current is equal to or greater than the first threshold value,

, &Lt; / RTI &gt;
Wherein a is a predetermined weight, x is a value of a second output current output from the second voltage conversion module, and N is a number of power conversion units. The method of claim 3,
And when the second output current is equal to or greater than the second threshold value,

, &Lt; / RTI &gt;
X is the value of the rated current of the battery energy storage system, x2 is the value of the limiting current of the battery energy storage system, , y1 is a grid allowable voltage variation value, and y2 is a limit voltage variation value of the battery energy storage system. The method according to claim 1,
Wherein,
Receiving the charging or discharging power amount of each power converting unit from the N power converting units,
And a value obtained by dividing a value obtained by adding up the charge or discharge power amount of each of the power conversion sections to the number of the power conversion sections is calculated as a shared power amount of the power conversion section. A control method of a battery energy management system having N power converters including a current controlled power converter and a voltage controlled power converter,
Calculating a shared power amount of the current controlled power converter;
Transmitting the shared power amount to the current controlled power converter; And
When the output current of the voltage controlled power converter becomes equal to or higher than a threshold value for a time before the current controlled power converter operates based on the shareable power amount, And controlling an output voltage of the battery. 10. The method of claim 9,
In the controlling step,
And increases the decrease amount of the output voltage exponentially if the output current is equal to or greater than the first threshold value and linearly increases the decrease amount of the output voltage when the output current is equal to or greater than the second threshold value, Of the battery energy storage system. 11. The method of claim 10,
Wherein the first threshold value is a value obtained by dividing a value of a rated current of the battery energy storage system by the number of the power conversion units and the second threshold value is a value of a rated current of the battery energy storage system. / RTI &gt; 10. The method of claim 9,
In the controlling step,
If the output current is equal to or greater than the first threshold value,

, &Lt; / RTI &gt;
And when the output current is equal to or greater than the second threshold value,

, &Lt; / RTI &gt;
Where x is a value of the rated current of the battery energy storage system, and x is a value of the rated current of the battery energy storage system, x2 is a value of a limit current of the battery energy storage system, y1 is a grid allowable voltage variation value, and y2 is a limit voltage variation value of the battery energy storage system. 10. The method of claim 9,
In the controlling step,
And controlling the gating reference voltage of the inverter included in the voltage controlled power converter to reduce the output voltage.

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