KR101736717B1 - Energy storage apparatus and method for controlling therof - Google Patents

Abstract

A control method of an energy storage device is disclosed. A method of controlling an energy storage device according to an embodiment of the present invention includes estimating power to be consumed at a lower stage, comparing a remaining capacity of the battery with the estimated power, ESS mode, and charging the battery when the remaining capacity of the battery is less than the estimated power.

Description

[0001] ENERGY STORAGE APPARATUS AND METHOD FOR CONTROLLING THEROF [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an energy storage device and a control method thereof, and more particularly, to an energy storage device and a control method thereof, And a method of controlling the same.

Domestic electricity supply and demand conditions exceed the expected demand power due to seasonal heating and cooling system operation, and as a result, large blackout (blackout) phenomenon may occur. Therefore, measures against peak power use and power outage should be prepared .

Therefore, UPS (Uninterruptible Power System) is used in case of power supply interruption in the power supply system in the lower part. However, since the UPS is not actually used in an emergency, it is not used most of the time It will end its life.

In addition, the development and dissemination of ESS (Energy Storage System) for demand power management at peak will result in double installation of ESS and UPS. In recent years, ESS for UPS, which operates as an ESS in an emergency, has become widespread. However, when the ESS is operating at a time when the power consumption is peak, and the power stored in the battery is being supplied, when the system is going to operate as a power failure due to a power failure, the energy stored in the battery is not enough to drive the load alone The power supply to the load may be interrupted.

Accordingly, there is a need for a power management device that can operate normally as an ESS but maintains energy sufficient to drive the subordinate stage alone, so that power can be supplied to the subordinate stage stably even if a power failure occurs in the system.

Korean Patent Publication No. 10-2014-0053590

SUMMARY OF THE INVENTION The present invention has been conceived to solve the problems described above. It is an object of the present invention to provide an ESS that normally operates as an ESS by predicting a power to be consumed in a load and maintaining a remaining battery capacity, And an energy storage device capable of stably supplying power to a lower end of the energy storage device and a control method thereof.

It is still another object of the present invention to provide an energy storage device and a control method thereof that can accurately predict the power consumption at the lower stage and utilize the energy storage device in various operating modes according to the predicted power consumption value.

The technical objects of the present invention are not limited to the above-mentioned technical problems, and other technical subjects not mentioned can be clearly understood by those skilled in the art from the following description.

According to an aspect of the present invention, there is provided a method of controlling an energy storage device, the method comprising: estimating power to be consumed at a lower end of the battery; comparing a remaining capacity of the battery with the estimated power; (ESS) mode if the remaining capacity of the battery is greater than the estimated power, and charging the battery if the remaining capacity of the battery is less than the estimated power.

According to an embodiment of the present invention, the step of estimating the power to be consumed at the lower stage may estimate the power to be consumed at the lower stage using a Kalman filter.

According to an embodiment of the present invention, estimating the power consumed at the lower stage may estimate power to be consumed at the lower stage by using an artificial neural network algorithm.

According to an embodiment of the present invention, the method may further include detecting power failure of the power system, and supplying power stored in the battery to the subsystem when a power failure occurs in the power system.

According to another aspect of the present invention, there is provided an energy storage apparatus including a battery, a power consumption estimating unit estimating power consumed by a battery, a battery management unit measuring a remaining capacity of the battery, Wherein the integrated controller operates in an ESS (ESS: Energy Storage System) mode if the remaining capacity of the battery is greater than the estimated power, and the remaining capacity of the battery is less than the estimated power The battery is charged.

According to an embodiment of the present invention, the power consumption estimating unit may estimate power to be consumed at the lower end using a Kalman filter.

According to an embodiment of the present invention, the power consumption estimation unit may estimate the power to be consumed at the lower stage by using an artificial neural network algorithm.

According to an embodiment of the present invention, the integrated controller may supply the electric energy stored in the battery to the lower stage when a power failure occurs in the power system.

The non-transiently readable recording medium according to another embodiment of the present invention may include a program for performing the above-described method.

According to the present invention, the ESS and the UPS are integrated and operated as a single device, thereby reducing the installation cost and the management cost.

In addition, when the energy storage device is operated in the ESS mode, even if a power failure occurs, a stable power can be supplied to the bottom of the UPS mode.

In addition, since the ESS mode is flexibly applied according to the estimated power consumption value at the lower end, it is possible to apply various charging plans such as CPP and TOU, thereby achieving the effect of more efficiently managing the electric charges.

1 is a block diagram illustrating an overall operation of an energy storage device in which a UPS and an ESS are combined according to an embodiment of the present invention.
2 is a view for explaining an energy storage device according to an embodiment of the present invention.
3 is a diagram for explaining a method of estimating power consumption at a lower stage by applying a Kalman filter according to an embodiment of the present invention.
4 is a diagram for explaining a method of estimating power consumption at a lower stage by applying a neural network technique according to an embodiment of the present invention.
FIG. 5 is a diagram for explaining a method of maintaining a remaining capacity of a battery in consideration of an emergency power source operating time according to an embodiment of the present invention. Referring to FIG.
6 is a flowchart illustrating a method of controlling an energy storage device according to an embodiment of the present invention.
FIG. 7 is a flowchart illustrating a method of controlling an energy storage device according to an embodiment of the present invention. Referring to FIG.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention and the manner of achieving them will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. To fully disclose the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

Unless defined otherwise, all terms (including technical and scientific terms) used herein may be used in a sense commonly understood by one of ordinary skill in the art to which this invention belongs. Also, commonly used predefined terms are not ideally or excessively interpreted unless explicitly defined otherwise.

Also, the singular forms herein may include plural forms unless specifically stated in the text. It is noted that the terms "comprises" and / or "comprising" used in the specification are intended to be inclusive in a manner similar to the components, steps, operations, and / Or additions.

1 is a block diagram illustrating an overall operation of an energy storage device in which a UPS and an ESS are combined according to an embodiment of the present invention.

ESS (Energy Storage System) is a system that can save the electric energy and use it when needed to improve the efficiency of energy use, enhance the utilization of renewable energy, and stabilize the power supply system. For example, a system that stores surplus power among the power supplied from the system at a low power consumption at night and provides the stored power to the load during the day when the power consumption shows a peak value.

Meanwhile, an uninterruptible power supply (hereinafter referred to as " UPS ") is a device that supplies high quality power by overcoming a power failure that may occur in a power supplying system. For this purpose, the UPS stores electric energy in the battery, and when the power failure occurs in the system, it supplies the stored electric energy to the battery, thereby providing stable power to the load.

The energy storage device 100 may store the power generated by the system 200 or the power generation system 300, and may supply power to the power storage system 200 or provide surplus power to the system 200. Also, the energy storage device 100 according to an embodiment of the present invention can operate as the above-described UPS and supply stable power to the lower stage when a power failure occurs in the system 200. [

The system 200 includes a power plant, a substation, a power station, and the like. When the system 200 is in a normal state, the power storage device 100 is supplied with electric power to allow the load terminal 400 to operate, and power generated from the power generation system 300 installed in the home or the factory may be received.

The power generation system 300 is a system for generating power using an energy source. The power generation system 300 can provide the produced power to the energy storage device 100. The power generation system 300 may be a solar power generation system, a wind power generation system, a tidal power generation system, or the like, but is not limited to the above-described types of power generation systems.

The load 400 consumes the power supplied from the energy storage device 100. For example, various electrical equipments installed in a factory or a home are examples of the load 400.

2 is a view for explaining an energy storage device according to an embodiment of the present invention.

Only the components related to the present embodiment are shown in the energy storage device 100 shown in FIG. Accordingly, those skilled in the art will recognize that other general-purpose components other than the components shown in FIG. 2 may be further included.

The energy storage device 100 shown in FIG. 2 includes a power consumption estimation unit 110, a battery 120, a battery management unit 130, and an integrated control unit 140.

The power consumption estimating unit 110 estimates power consumption to be consumed at the lower end in a predetermined time interval. When the power supply is shut off due to a power failure in the system 200, in order for the energy storage device 100 to operate in the UPS mode and supply power to the load 400 in a stable manner, .

Therefore, the power consumption estimation unit 110 estimates the power to be consumed at the subordinate stage using an neural network technique or an optimization algorithm such as a Kalman filter.

The power consumption estimation unit 110 may estimate the power consumed in the load 400 using the Kalman filter according to an embodiment of the present invention.

The Kalman filter is a technique used in various fields of control and time series data. It is used to express the time series data in a state space model and obtain the desired estimation value through the measurement value. The Kalman filter accepts new measurements repeatedly, and in most cases it has the advantage of quickly converging to true values regardless of the initial value. In addition, since it is not necessary to memorize all the past data, the time required for calculation is short, and every time the algorithm is repeated, the updated weight is given according to the error between the measured value and the predicted value.

The state space model can be expressed by a state equation expressed by Equation (1) and a measurement equation expressed by Equation (2).

In the above two equations, X _t represents the state variable and Z _t represents the measured value. The system noise w _t is a standard deviation of true values known from long observations and fabrication, Is a distributed noise variable. Also, Vt represents the noise included in the measurement and is a noise variable having a covariance matrix V. The details of predicting the power consumption of the load 400 with the above-described Kalman filter will be described with reference to FIG.

When the power consumption estimation unit 110 uses the neural network technique, if the past consumption power value of the load 400 and the variation amount of the past consumption power are mathematically processed by the input value, according to another embodiment of the present invention, The power consumption of the load 400 can be predicted.

At this time, the error can be further reduced by correcting the constant value used in the above mathematical process with the difference between the predicted power consumption and the actual power consumption. A specific method of estimating the power consumption of the load 400 by the neural network technique will be described with reference to FIG.

The battery 120 receives and stores electrical energy from the system 200 or the power generation system 300 and supplies power to the load 400. The battery 120 is a name collectively referred to as a structure having a plurality of battery sub-units. A battery constituting the battery 120 is basically composed of an anode, a cathode, an electrolyte, and a separator. A cell made of such a component is called a cell. The plurality of cells again form a module, and a plurality of modules gather together to form a rack. As described above, the reason why the battery is divided into stages is that the characteristics of each battery cell are different from each other and a difference that can be controlled is required.

Meanwhile, the battery 120 may be one of a nickel battery, an ion battery, a lithium ion battery, a polymer battery, a lithium polymer battery, and a lithium sulfide battery as a rechargeable / rechargeable secondary battery.

The battery management unit 130 measures the remaining capacity of the battery 120. The battery management unit 130 may use a voltage measurement method, a current measurement method, or the like in order to measure the remaining capacity of the battery 120. [ However, the above-described remaining capacity measuring method is illustrative and not restrictive.

Also, the battery management unit 130 may perform an overcharge protection function, an over discharge protection function, an over current protection function, an over voltage protection function, an overheat protection function, a cell balancing function, and the like of the battery 120. To this end, the battery management unit 130 may include measurement means for measuring voltage, current, temperature, remaining power, and life of the battery 120.

The battery management unit 130 may supply power to the load 400 by charging the battery 120 or discharging the battery 120 under the control of the integrated controller 140. [

The integrated control unit 140 controls the overall operation of the energy storage device 100. The integrated controller 140 may cause the energy storage device 100 to perform a normal ESS operation if the remaining capacity of the battery 120 is greater than the estimated power consumption of the load 400, When the capacity is smaller than the estimated power consumption of the load 100, the battery 120 is charged.

A typical ESS operation is to store surplus power in the battery 120 if the power supplied from the system 200 or the power generation system 300 is greater than the power consumed in the load 400, The power stored in the battery 120 is supplied to the load 400.
When the energy stored in the battery 120 is supplied to the load 400 because the power consumption of the load 400 is equal to or greater than the threshold value, the remaining capacity of the battery 120 becomes smaller than the power consumed in the load 400 May occur. In this case, if a power failure occurs in the system 200 and the connection to the system 200 is interrupted, the energy storage device 100 alone must supply power to the load 400. However, if the residual capacity of the battery 120 is insufficient So that power can not be supplied.

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Accordingly, the integrated controller 140 charges the battery 120 if the remaining capacity of the battery 120 is less than the estimated power consumption of the load 100. [ That is, the remaining capacity of the battery 120 is maintained to be higher than the estimated power to be consumed in the load 400. [ For example, the integrated control unit 140 controls the power consumption of the load 400 estimated by the power consumption estimation unit 110 to be the sum of the loss margin obtained by the operation of the energy storage device 100 And may be stored in the battery 120.

If the remaining capacity of the battery 120 is maintained at a level higher than the power consumed in the load 400 as described above, even if power is not supplied from the system 200, 400 can be stably supplied with power.

3 is a diagram for explaining a method of estimating power consumption at a lower stage by applying a Kalman filter according to an embodiment of the present invention.

The state variable xt of the state space model for predicting the power consumed in the load 400 in a predetermined time unit can be defined as follows.

P _L is the load 400 at the time point t, and? P is the load 400 change amount. If the measured value Z _k is a load, the state transition matrix A and the output matrix H can be expressed as follows.

From the above equations, equations (1) and (2) of the state space model can be expressed by equations (5) and (6).

Equation (5) shows that the current load 400 amount at time t + 1 is the sum of the amount of load 400 at time t and the amount of load 400 at time t. Equation (6) indicates that measurement noise is present in the measurement of the load (400). The system noise wt and vt included in the above two equations can be expressed as a covariance matrix of W and V in the Kalman filter, respectively, and appropriate values can be used analytically or experimentally.

The power consumption prediction operation of the load 400 using the Kalman filter through the above-described process is as follows. First, the Kalman gain is calculated based on the initial power consumption input value (S310) of the initial load 400 (S320). The Kalman gain is updated every time the Kalman filter is repeatedly performed, and the error Lt; / RTI > In the next step, an estimated value reflecting an error between the power consumption of the load 400 measured at the current time point and the consumption strategy value of the predicted load 400 is calculated (S330). This estimate is used to predict the power consumption of the load 400 at the next time point. In the next step, the error covariance reflecting the error in the previous step is calculated (S340), and finally the predicted value of the next time is calculated (S350).

As described above, when the power consumption of the load 400 is estimated using the Kalman filter, the error can be minimized.

4 is a diagram for explaining a method of estimating power consumption at a lower stage by applying a neural network technique according to an embodiment of the present invention.

According to an embodiment of the present invention, the power consumption estimation unit 110 may estimate the power consumption of the load 400 using the forward artificial neural network model as shown in FIG. The forward artificial neural network according to an embodiment of the present invention may include an input layer 410, a hidden layer 420, and an output layer 430. In the hidden layer 420, a sigmoid function can be used as an active function.

The input layer 410 according to an embodiment of the present invention constitutes seven input values with four past power consumption values. Specifically, x1, x2, x3, and x4 are past power consumption input values, and? 1,? 2, and? 3 are variations of input values.

The seven input values described above are developed in the concealment step 420. The weight W is determined according to the specific gravity and variation of each value while passing through the hidden layer 420, and the following operation is performed.

The sum of the d values determined in this way can estimate the power consumption of the load 400 for each time period.

On the other hand, in order to minimize the error between the estimated value and the actual measured value, it is possible to apply the inversion method of the artificial neural network to the weight of the hidden layer 420 and then modify the value. In addition, the above-described modification can be repeated until the difference between the power consumption of the estimated load 400 and the actually measured value becomes smaller than a preset value.

Specifically, the amount of change in V can be determined by determining the amount of change in V in Equation (7) with an error between the estimated power consumption and the measured power consumption, and applying the value to the differential value of the sigmoid function. The power consumption of the load 400 estimated through the above process can be utilized to determine whether to charge the battery 120 or to drive the energy storage device 100 in the ESS mode.

FIG. 5 is a diagram for explaining a method of maintaining a remaining capacity of a battery in consideration of an emergency power source operating time according to an embodiment of the present invention. Referring to FIG.

The integrated controller 140 supplies power to the load 400 and stores the surplus power in the battery 120 in a state where power is stably supplied from the system 200 in the first steady state period 510. [ And controls the battery management unit 130 so that energy greater than the power consumption of the load 400 estimated by the power consumption estimation unit 110 is stored in the battery 120. [

The integrated controller 140 switches the energy storage device 100 to the UPS mode in the abnormal state section 520 where power is not supplied to the system 200 and the power is not normally supplied, 400).

Thereafter, the discharged battery 120 is charged in the second steady state period 520 in which power is normally supplied from the system 200 again.

At this time, the power consumption estimating unit 110 estimates the power to be consumed in the load 400, and the integrated controller 140 controls the battery 120 (e.g., the battery 120) until the remaining capacity of the battery 120 becomes greater than the estimated consumed power. ).

Under normal ESS operation, some power is supplied from the battery 120 if the power consumed in the load 400 exceeds a predetermined value, but even if the remaining capacity of the battery 120 is less than the power to be consumed in the load 400 When the battery 120 is discharged, the integrated controller 140 can not supply power to the load 400 in a non-steady state in which the connection with the system 200 is cut off, And controls the battery management unit 130 to maintain the battery. Specifically, the battery management unit 130 is controlled such that energy higher than a power value expected to be consumed in the load 400 is stored in the battery 120. [

According to an embodiment of the present invention, the integrated control unit 140 controls the amount of energy to be consumed in the load 400 by adding the loss power generated by the operation of the energy management apparatus 100 to the power consumed in the load 400 And controls the battery management unit 130 to store the battery. Under the control of the integrated controller 140, the battery management unit 130 charges the battery 120 such that the remaining capacity of the battery 120 is maintained at a predetermined level or more.

If the remaining capacity of the battery 120 is maintained at a level higher than the power consumed in the load 400 as described above, even if power is not supplied from the system 200, 400 can be stably supplied with power.

6 is a flowchart illustrating a method of controlling an energy storage device according to an embodiment of the present invention.

The power consumption estimating unit 110 estimates the power consumed by the load 400. [ Specifically, the power consumption estimation unit 110 can estimate the power to be consumed in the load 400 using one of the neural network technique or the Kalman filter algorithm.

The integrated control unit 140 compares the power consumption of the load 400 estimated by the power consumption estimation unit 110 with the remaining capacity of the battery 120 measured by the battery management unit 130.

The integrated controller 140 controls the energy storage device 100 to operate in the ESS mode if the remaining battery charge of the battery 120 is greater than the estimated consumed power and if the remaining capacity of the battery 120 is less than the estimated remaining capacity, And controls the battery management unit 130 to charge the battery 120. [ The integrated controller 140 charges the battery 120 if the remaining capacity of the battery 120 is less than the power consumed in the load 400 even if the power consumed in the load 400 is equal to or greater than a predetermined value. At this time, the integrated controller 140 controls the battery management unit 130 to store the energy, which is the sum of the power estimated to be consumed in the load 400 and the loss power of the energy storage device 100, .

If the remaining capacity of the battery 120 is maintained at a level higher than the power consumed in the load 400 as described above, even if power is not supplied from the system 200, 400 can be stably supplied with power.

FIG. 7 is a flowchart illustrating a method of controlling an energy storage device according to an embodiment of the present invention. Referring to FIG.

The integrated control unit 140 determines whether power is normally supplied from the system 200 (S710). If a power failure occurs in the system 200 in step S720, for example, if a blackout occurs, the integrated controller 140 switches the energy storage device 100 to the UPS mode, To the bottom. Thereafter, when the connection with the system 400 is normally restored, the integrated controller 140 operates the energy storage device 100 in the ESS mode.

The ESS mode is a mode in which the power supplied from the system 400 is supplied to the load 400 and remaining power is stored in the battery 120. When the power consumed by the load 400 exceeds a preset value, And the energy stored in the storage unit 120 is supplied to efficiently manage the power.

Thereafter, the integrated controller 140 compares the power consumption of the load 400 estimated by the power consumption estimation unit 110 with the remaining capacity of the battery 120 measured by the battery management unit 130 (S750). When it is determined that the remaining capacity of the battery 120 is greater than the power consumed in the load 400, the energy storage device 100 operates in the ESS mode (S770) and determines that the remaining capacity is less than the power to be consumed in the load 400 The battery 120 is charged.

Meanwhile, the above-described method can be implemented in a general-purpose digital computer that can be created as a program that can be executed by a computer and operates the program using a computer-readable recording medium. In addition, the structure of the data used in the above-described method can be recorded on a computer-readable recording medium through various means. The computer-readable recording medium includes a storage medium such as a magnetic storage medium (e.g., ROM, floppy disk, hard disk, etc.), optical reading medium (e.g., CD ROM,

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Therefore, the disclosed methods should be considered from an illustrative point of view, not from a restrictive point of view. The scope of the present invention is defined by the appended claims rather than by the foregoing description, and all differences within the scope of equivalents thereof should be construed as being included in the present invention.

100: Energy storage device 110: Power consumption estimation part
120 battery 130 battery management section
140: Integrated controller 200:
300: Power generation system 400: Load

Claims (10)

Estimating power to be consumed at the lower stage;
Comparing the estimated power with a remaining capacity of the battery; And
Charging the battery when the remaining capacity of the battery is greater than the estimated power and operating in an energy storage system (ESS) mode and the remaining capacity of the battery is equal to or less than the estimated power; , ≪ / RTI &
The ESS mode supplies power stored in the battery to the lower stage until the remaining capacity of the battery becomes equal to the power estimated to be consumed at the lower stage when the power consumed at the lower stage exceeds a predetermined threshold value The method comprising: The method according to claim 1,
Estimating a power to be consumed at the lower stage,
And estimating a power to be consumed at the lower stage by using a Kalman filter. The method according to claim 1,
Estimating a power to be consumed at the lower stage,
And estimating power to be consumed at the lower stage by using an artificial neural network algorithm. The method according to claim 1,
Detecting power failure of the power system;
And supplying the electric energy stored in the battery to the lower stage when a power failure occurs in the power system. battery;
A power consumption estimating section for estimating a power consumed by the lower stage;
A battery management unit for measuring a remaining capacity of the battery; And
And an integrated controller for comparing the estimated power with a remaining capacity of the battery,
The integrated control unit,
And operates in an ESS (Energy Storage System) mode if the remaining capacity of the battery is greater than the estimated power, and charges the battery when the remaining capacity of the battery is equal to or less than the estimated power,
The ESS mode supplies power stored in the battery to the lower stage until the remaining capacity of the battery becomes equal to the power estimated to be consumed at the lower stage when the power consumed at the lower stage exceeds a predetermined threshold value Energy storage device. 6. The method of claim 5,
Wherein the power consumption estimating unit estimates,
And estimates power to be consumed at the lower stage by using a Kalman filter. 6. The method of claim 5,
Wherein the power consumption estimating unit estimates,
An energy storage device for estimating a power to be consumed at the lower stage by using an artificial neural network algorithm. 6. The method of claim 5,
The integrated control unit,
And an electric energy stored in the battery is supplied to the lower stage when a power failure occurs in the power system. A non-transitory computer readable recording medium recording a program for performing the method according to any one of claims 1 to 4. Estimating a power to be consumed in the emergency load among the load stages including the normal load and the emergency load;
Comparing the estimated power with a remaining capacity of the battery; And
Charging the battery when the remaining capacity of the battery is greater than the estimated power and operating in an energy storage system (ESS) mode and the remaining capacity of the battery is equal to or less than the estimated power; , ≪ / RTI &
The ESS mode supplies power stored in the battery to the normal load until the remaining capacity of the battery becomes equal to the power estimated to be consumed in the emergency load when the power consumed at the lower stage exceeds a predetermined threshold value The method comprising:

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