WO2013005875A1 - Coordination control system and method for a micro-grid energy storage device - Google Patents

Abstract

The present invention relates to a coordination control system and method for a micro-grid energy storage device for controlling an output amount of an energy storage device having no SOC characteristics according to a current output of an energy storage device having SOC characteristics on the basis of a load amount (or an output amount) calculated using current outputs of energy storage devices in a central control device in order to stabilize an output of a micro-grid. The suggested coordination control system of a micro-grid energy storage device includes: a central control device for setting an output value command to control an output of an energy storage device having no SOC characteristics on the basis of a current output value and an SOC value received from a plurality of distributed power supplies and energy storage devices; a first energy storage device for transmitting a current output value and an SOC value to the central control device and controlling an output of a droop control; and a second energy storage device for transmitting a current output value to the central control device and controlling an output on the basis of an output value command received from the central control device.

Description

Cooperative control system and method of energy storage device for microgrid

The present invention relates to a cooperative control system and method of the energy storage device for microgrids (THE COORDINATED CONTROL SYSTEM AND METHOD OF ENERGY STORAGE DEVICE FOR MICROGRID), and more particularly, to SOC in a microgrid system capable of centralized control and local control. The present invention relates to a cooperative control system and method for an energy storage device for a microgrid that performs cooperative control between an energy storage device having characteristics and an energy storage device having no SOC characteristics.

The invention claims the benefit of the filing date of Korean Patent Application No. 10-2011-0066233 filed on July 5, 2011, the entire contents of which are incorporated herein.

In general, a microgrid system is a small power supply system near a demand, which can supply power and heat simultaneously. At this time, the microgrid system separates from the power system when an accident or failure occurs in the power system, and performs an independent operation of controlling the power supply to the load from a plurality of distributed power sources constituting the microgrid. At this time, the microgrid system controls the output of the distributed power supply in a central control method to maintain the balance of power supply and supply by satisfying the load variation in the load through various types of control. That is, the microgrid central control method monitors distributed power supply and load and collects related information such as voltage and frequency from the central control unit. The central control unit uses the collected information to send the output value instructions of the distributed power supply and energy storage device back to the distributed power supply and energy storage device.

However, the central control method of the microgrid system transmits information such as voltage and frequency from the distributed power supply and the load to the central control device through communication, so it is difficult to deteriorate the electrical quality and maintain the power supply and demand balance due to communication delay. There is this.

In addition, the local control method of the microgrid system is capable of autonomous operation of the microgrid by using voltage and frequency information, but should be composed of a distributed power supply having high dynamic characteristics. However, the distributed power supply having high dynamic characteristics has a limitation in the amount of charge and discharge of energy, and thus there is a problem that long-term operation is possible only by using a plurality of distributed power supplies.

The present invention has been proposed to solve the above-described problems, and based on the load amount (or output amount) calculated using the current output of the energy storage devices in the central control unit, the current output of the energy storage device having the SOC characteristic is determined. Accordingly, an object of the present invention is to provide a cooperative control system and method of an energy storage device for a microgrid, which controls an output amount of an energy storage device having no SOC characteristic to stabilize the output of the microgrid.

Another object of the present invention is to determine the internal load variation of the microgrid as a short period load and a long period load by using a low pass filter, so that the SOC of the energy storage device having an SOC through cooperative control between energy storage devices in the microgrid. The present invention provides a cooperative control system and method for an energy storage device for a microgrid to quickly recover a set value.

In order to achieve the above object, the cooperative control system for an energy storage device for a microgrid according to an embodiment of the present invention has no SOC characteristics based on current output values and SOC values received from a plurality of distributed power supplies and energy storage devices. A central controller for setting an output value command for controlling the output of the energy storage device; A first energy storage device for transmitting the current output value and the SOC value to the central control device, and controlling the output by droop control; And a second energy storage device for transmitting the current output value to the central controller and controlling the output based on the output value command received from the central controller.

The central controller includes: a load calculation unit configured to calculate a load of the microgrid system by summing a plurality of distributed power supplies and current output values received from the first energy storage device and the second energy storage device; A load amount classifying unit classifying the load amount calculated by the load amount calculating unit into a long period load amount and a short period load amount; And a control unit for setting the output value command based on the long period load amount classified by the load amount classification unit and the SOC value from the first energy storage device, and transmitting the output value command to the second energy storage device.

The load classifier includes a low pass filter.

The load amount classifying unit classifies the long period load amount if the load amount calculated by the load calculating unit passes the low pass filter.

The control unit sets the value calculated by summing the SOC value received from the first energy storage device and the long period load amount classified by the load amount classification unit as the output value command of the second energy storage device.

The first energy storage device includes a battery having SOC characteristics, and the second energy storage device includes a fuel cell without SOC characteristics.

The first energy storage device controls the output through local control by droop control.

The first energy storage device includes a reference value setting unit for setting an output reference value of the first energy storage device based on the load amount from the central controller; A control mode setting unit configured to set a control mode of the first energy storage device by comparing the load amount with an output reference value when the load amount calculated by the central controller is a short period load amount; And an output control unit controlling an output of the first energy storage device according to the control mode set by the control mode setting unit.

The reference value setting section sets the output setting value including the excess load amount and the underload amount.

The control mode setting unit sets the charge control mode when the load amount is less than the excess load amount, sets the current control mode when the load amount is less than the excess load amount or less than the underload amount, and sets the discharge control mode when the load amount exceeds the underload amount.

 The output control unit controls the first energy storage device to charge at the maximum output when the charging mode is set in the control mode setting unit, and the load fluctuation amount excluding the amount of power preset in the power system when the tidal current control mode is set in the control mode setting unit. The first energy storage device is controlled to output power for the control, and when the control mode setting unit is set to the discharge control mode, the first energy storage device is controlled to discharge at the maximum output.

The second energy storage device includes a control mode setting unit for setting a control mode of the second energy storage device based on an output value command and a load setting value received from the central control device; And an output control unit controlling an output of the second energy storage device according to the control mode set by the control mode setting unit.

If the output value command is less than the first load setting value, the control mode setting unit sets the UPC first mode. If the output value command is greater than or equal to the first load setting value and less than or equal to the second load setting value, the control mode setting unit is set to the tidal current control mode. If the second load setting value is exceeded, set the UPC to the second mode.

The first load set value is the sum of the minimum output value of the second energy storage device and the power system inflow power amount, and the second load set value is the sum of the maximum output value of the second energy storage device and the power system inflow power amount.

The output control unit controls the second energy storage device to output power at the minimum output when the control mode setting unit is set to the UPC first mode, and sets the preset power in the power system when the control mode setting unit is set to the tidal current control mode. Outputs and controls the power of the load to subtract the power output from the power system from the load, and outputs the power at the maximum output when the control mode setting unit is set to the UPC second mode. Control storage.

The output control unit controls the output of the second energy storage device to be zero when the UPC mode is set and is less than the minimum output of the output value command second energy storage device, and the output control unit is set to the UPC mode and set to the output value command second energy storage device. If the minimum output is greater than the first load set value, the second energy storage device is controlled to output at the minimum output.

In order to achieve the above object, a cooperative control method of an energy storage device for a microgrid according to an embodiment of the present invention receives a current output value and an SOC value from a plurality of distributed power supplies, a first energy storage device, and a second energy storage device. Making; Calculating a load of the microgrid system based on a plurality of distributed power sources and current output values received from the first energy storage device and the second energy storage device; Classifying the calculated load into a long period load and a short period load; Setting an output value command of the second energy storage device based on the classified long period load amount and the SOC value from the first energy storage device; And controlling the output of the second energy storage device based on the set output value command.

In the calculating of the load, the load of the microgrid system is calculated by summing a plurality of distributed power supplies and current output values received from the first energy storage device and the second energy storage device.

In the step of classifying the long period load and the short period load, if the calculated load passes the low pass filter, it is classified as the long period load.

In the step of setting the output value command, a value calculated by summing the SOC value received from the first energy storage device and the classified long period load amount is set as the output value command of the second energy storage device.

In the step of controlling the output of the second energy storage device, if the output value command is less than the first load setting value, the control unit sets the UPC first mode, and if the output value command is more than the first load setting value and less than the second load setting value, the flow control Mode, and if the output value command exceeds the second load setting value, the mode is set to UPC second mode.

The first load set value is the sum of the minimum output value of the second energy storage device and the power system inflow power amount, and the second load set value is the sum of the maximum output value of the second energy storage device and the power system inflow power amount.

In the controlling of the output of the second energy storage device, when the UPC is set to the first mode, the second energy storage device is controlled to output power at the minimum output, and when the tidal current control mode is set, the preset power is output from the power system. And outputs the power of the load subtracted from the power output from the power system in the second energy storage device, and controls the second energy storage device to output power at the maximum output when the UPC is set to the second mode.

In the controlling of the output of the second energy storage device, if the output mode is set to the UPC mode and is less than the minimum value of the output value command second energy storage device, the output of the second energy storage device is controlled to be 0 and set to the UPC mode. When the output value command is greater than or equal to the minimum output of the second energy storage device and less than the first load set value, the second energy storage device is controlled to output at the minimum output power.

Controlling the output of the first energy storage device through the local control by the droop control.

The controlling of the output of the first energy storage device may include: setting an output reference value of the first energy storage device based on the calculated load amount; Setting the control mode of the first energy storage device by comparing the load amount with the calculated output reference value when the calculated load amount is a short period load amount; And PI controlling the output of the first energy storage device according to the control mode.

In the step of setting the output reference value, an output set value including an excess load amount and an underload amount is set.

In the step of setting the control mode of the first energy storage device, if the load amount is less than the excess load amount, the charging control mode is set; if the load amount is less than the excess load amount or less than the load amount, the flow rate control mode is set; Set to discharge control mode.

In the controlling of the output of the first energy storage device, when the charging control mode is set, the first energy storage device is controlled to charge at the maximum output, and when the tidal current control mode is set, the load fluctuation amount excluding the predetermined power amount is set in the power system. The first energy storage device is controlled to output power for the control, and when the discharge control mode is set, the first energy storage device is controlled to discharge at maximum output.

Receiving the current output value and SOC value, Receiving the current output value from a plurality of distributed power supply step Receiving the current output value and SOC value from the first energy storage device having a SOC characteristic; And receiving a current output value from a second energy storage device having no SOC characteristic.

According to the present invention, the cooperative control system and method of the energy storage device for the microgrid divides the load variation of the microgrid into a long period load and a short period load so that the long period load does not have an SOC and a slow dynamic energy storage device (ie, a fuel cell). ), And the short-cycle load is in charge of the energy storage device (that is, the battery) with SOC, and mutually performs cooperative control to maintain the power supply balance of the microgrid, and system power flows into the microgrid. It is effective to keep it constant.

In addition, the cooperative control system and method of the energy storage device for the microgrid is responsible for supplying power to the load by the energy storage device fully responsible for the load fluctuations inside the microgrid regardless of the time. In case of exceeding the load fluctuation, the power system is responsible for the load, and the battery is switched to the unit control mode that produces a constant output to balance the power supply and supply, thereby effectively operating the microgrid.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a view for explaining the configuration of a microgrid cooperative control system for explaining an embodiment of the present invention.

2 is a view for explaining the configuration of the first energy storage device of FIG.

3 is a view for explaining the configuration of the second energy storage device of FIG.

4 is a view for explaining the configuration of the central control device of FIG.

5 is a flowchart illustrating a cooperative control method of an energy storage device for a microgrid according to an embodiment of the present invention.

FIG. 6 is a flowchart for describing a step of controlling a second energy storage device having no SOC characteristic of FIG. 5.

FIG. 7 is a flowchart for describing a step of controlling a first energy storage device having SOC characteristics of FIG. 5.

8 is a view for explaining an operation mode of a second energy storage device having no SOC characteristic.

9 to 11 are views for explaining the operation mode of the first energy storage device having SOC characteristics.

Hereinafter, the preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the technical idea of the present invention. . First of all, in adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are used as much as possible even if displayed on different drawings. In addition, in describing the present invention, when it is determined that the detailed description of the related well-known configuration or function may obscure the gist of the present invention, the detailed description thereof will be omitted.

First, the present invention relates to a cooperative control system and method for performing cooperative control between distributed power supplies in a microgrid system capable of centralized control and local control by a central controller.

The cooperative control system of the energy storage device for the microgrid performs cooperative control between the energy storage devices in the microgrid system capable of central control by the local control and the central control device. At this time, the load variation of the microgrid is divided into a long period component and a short period component. Therefore, the cooperative control system of the energy storage device for microgrid has the dynamic characteristics of the energy storage device having the SOC characteristic, so that it can handle the load fluctuation of the short period component, and the energy storage device such as the fuel cell without the SOC characteristic has the slow dynamic characteristics. Since the output can be produced regardless of time, it controls to handle the load variation of long period component.

More specifically, in the first control step, the central control apparatus receives the output amount and SOC of each distributed power supply and calculates the microgrid internal load amount. Then, the microgrid internal load variation is extracted as the short period and long period variation by the low pass filter. In this case, a low pass filter is used to classify the load variation into short and long period components. In other words, if the amount that the distributed power supply must pass passes through the low pass filter, it is regarded as a long period component and other components are regarded as short period components.

The additional output is added to the long period load variation so that the received SOC value remains within the acceptable range (10 to 100%). If the SOC is 100%, the output of the fuel cell is instructed so that the battery can no longer be charged by reducing the load fluctuation of the long period.If the SOC is 10%, the battery no longer discharges by increasing the load fluctuation of the long period. Command the output of the fuel cell to prevent it.

 Next, in the second control step, the control device of each distributed power supply switches to an appropriate control mode of UPC and FFC in consideration of the load amount and output capacity of the distributed power supply, thereby stabilizing the output of the microgrid. In the central controller, the controller of the energy storage device without SOC whose output is commanded by calculating the long-term load and the load for SOC management is converted to the appropriate control mode of UPC and FFC in consideration of the output capacity and output through PI control. To control. On the other hand, the energy storage device with SOC capable of local control through droop control is converted to the appropriate control mode of UPC and FFC by considering the output amount and output capacity by droop control without command of the central controller, and the output is controlled through PI control. To control. The energy storage device with SOC has fast output dynamic characteristics, so it can react quickly to load fluctuations without command of the central controller, thereby maintaining power supply balance and improving power quality. Therefore, the present invention is expected to be applied to improve the power quality of the micro grid and maintain the power supply and demand balance when the spread of the micro grid is expanded in the future.

Batteries, which are energy storage devices with SOC, are installed above the fuel cells, and output control is performed through regional control through droop control. When the microgrid is separated from the grid by droop control and the power from the grid becomes “0”, the frequency changes. The battery output is increased by the set droop coefficient to maintain the power supply balance of the microgrid.

The fuel cell, which is an energy storage device without SOC, receives the output of the battery and the fuel cell from the central controller by a central control method. In addition, the fuel cell compares the SOC and SOC set values in order to keep the SOC of the battery constant and adds this value to the fuel cell input through the PI controller.

In the present invention, the load is estimated using the output of the energy storage device, and the command value is transmitted to the energy storage device having no SOC characteristics and slow dynamic characteristics, and the energy storage device having fast SOC characteristics but high dynamic characteristics has a load variation and dynamic characteristics. It is a way to balance power by dealing with the difference in output value of a slow energy storage device. This can reduce the capacity of energy storage devices that have fast dynamic characteristics like SOC and have SOC characteristics, and help the SOC management of energy storage devices with SOC characteristics as long-term components are handled by energy storage devices such as fuel cells without SOC characteristics. It has the advantage of maintaining the output balance regardless of time.

Hereinafter, the cooperative control system of the microgrid energy storage device according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. 1 is a view for explaining the configuration of a microgrid cooperative control system for explaining an embodiment of the present invention. 2 is a view for explaining the configuration of the first energy storage device of FIG. 1, FIG. 3 is a view for explaining the configuration of the second energy storage device of FIG. 1, FIG. It is a figure for demonstrating a structure. In the embodiment of the present invention, the energy storage device is collectively referred to as a device for storing and outputting chemical energy, electrical energy, and the like, if necessary, and is not limited to general energy storage devices.

As shown in FIG. 1, the cooperative control system of the microgrid energy storage device includes a plurality of distributed power sources 100, a first energy storage device 200, a second energy storage device 300, and a central control device 400. It is configured to include). At this time, the plurality of distributed power source 100, the first energy storage device 200 and the second energy storage device 300 is a load (through the power line 700 connected to the distribution transformer 500 and the stationary switch 600) 800, and transmits and receives data to and from the central controller 400 through the network 900.

The distributed power source 100 is composed of a micro turbine, a fuel cell, a diesel generator, and the like, and is connected to a load 800 through an AC power line 700 connected to a distribution transformer 500 and a stationary switch 600. The distributed power supply 100 transmits the current output value to the central control unit 400 through the network 900.

The first energy storage device 200 transmits the current output value and the SOC value to the central controller 400, and outputs power to the load 800 by droop control. In this case, the first energy storage device 200 includes a battery 280 having SOC characteristics. To this end, as shown in FIG. 2, the first energy storage device 200 includes a reference value setting unit, a control mode setting unit 240, and an output control unit 260. Here, the first energy storage device 200 may be configured to include a communication unit (not shown) for transmitting and receiving data with the central control unit 400.

The reference value setting unit sets the output reference value of the first energy storage device 200 based on the load amount from the central controller 400. Here, the reference value setting section sets the output setting value including the excess load amount and the underload amount.

The control mode setting unit 240 sets the control mode of the first energy storage device 200 by comparing the load amount and the output reference value when the load amount calculated by the central controller 400 is a short period load amount. Here, the control mode setting unit 240 is set to the charge control mode if the load is less than the excess load amount, and set to the tidal current control mode if the load amount is less than the excess load amount or less than the underload load, and to the discharge control mode if the load amount exceeds the underload load. Set it.

The output controller 260 controls the output of the first energy storage device 200 according to the control mode set by the control mode setting unit 240. Here, the output control unit 260 controls the first energy storage device 200 to charge at the maximum output when the control mode setting unit 240 is set to the charging control mode, and the current control mode in the control mode setting unit 240 When the power system is set to control the first energy storage device 200 to output the power for the change amount of the load 800, except for the amount of power set in advance, the maximum output when the control mode setting unit 240 is set to the discharge control mode The first energy storage device 200 is controlled to discharge.

The second energy storage device 300 transmits the current output value to the central control unit 400 and controls the output based on the output value command received from the central control unit 400. In this case, the second energy storage device 300 includes a fuel cell 360 having no SOC characteristic. To this end, as shown in FIG. 3, the second energy storage device 300 includes a control mode setting unit 320 and an output control unit 340. Here, the second energy storage device 300 may be configured to include a communication unit (not shown) for data transmission and reception with the central control unit 400.

The control mode setting unit 320 sets the control mode of the second energy storage device 300 based on the output value command and the load 800 setting value received from the central controller 400. Here, the control mode setting unit 320 sets the UPC first mode if the output value command is less than the first load 800 setting value, and the output value command is greater than or equal to the first load 800 setting value and the second load 800. If it is less than the set value, it is set to the tidal current control mode, and if the output value command exceeds the set value of the second load 800, it is set to the UPC second mode. In this case, the control mode setting unit 320 sets a value obtained by adding the minimum output value of the second energy storage device 300 and the amount of power input into the power system as the first load 800 setting value, and the second energy storage device 300. The control mode of the second energy storage device 300 is set based on the sum of the maximum output value and the amount of power supplied to the power system as the second load 800.

The output controller 340 controls the output of the second energy storage device 300 according to the control mode set by the control mode setting unit 320. Here, when the control mode setting unit 320 is set to the UPC first mode, the output control unit 340 controls the second energy storage device 300 to output power at the minimum output, and in the control mode setting unit 320. When the current control mode is set, the power is output from the power system and the power of the load 800 subtracted from the power output from the power system is output from the second energy storage device 300, and the control mode is set. When the unit 320 is set to the second UPC mode, the second energy storage device 300 is controlled to output power at the maximum output.

The central controller 400 sets an output value command for controlling the output of the energy storage device having no SOC characteristic based on the current output value and the SOC value received from the energy storage devices. To this end, as shown in FIG. 4, the central control unit 400 includes a communication unit 420, a load amount calculation unit 440, a load amount classification unit 460, and a control unit 480.

The communication unit 420 transmits and receives data to and from a plurality of distributed power sources 100 and energy storage devices (ie, the first energy storage device 200 and the second energy storage device 300).

The load calculator 440 calculates the load of the microgrid system by summing the current output values received from the plurality of distributed power supplies 100, the first energy storage device 200, and the second energy storage device 300.

The load amount classification unit 460 classifies the load amount calculated by the load amount calculation unit 440 into a long period load amount and a short period load amount. At this time, the load amount classifying unit 460 is configured as a low pass filter, and if the load calculated by the load calculating unit 440 passes the low pass filter, it is classified as a long period load amount. If the load calculated by the load calculator 440 does not pass the low pass filter, it is classified as a short period load. Here, the cutoff frequency of the low pass filter is set differently according to the energy storage device having a slow dynamic characteristic.

The controller 480 sets an output value command based on the long period load amount classified by the load amount classifying unit 460 and the SOC value from the first energy storage device 200, and sends the output value command to the second energy storage device 300. Control to transmit. At this time, the control unit 480 is a second energy storage device is calculated by summing the SOC value received from the first energy storage device 200 through the communication unit 420 and the long period load amount classified by the load amount classification unit 460. (300) is set to the output value command.

Hereinafter, the cooperative control method of the microgrid energy storage device according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. 5 is a flowchart illustrating a cooperative control method of an energy storage device for a microgrid according to an embodiment of the present invention. FIG. 6 is a flowchart illustrating a step of controlling a second energy storage device having no SOC characteristic of FIG. 5, and FIG. 7 is a flowchart illustrating a step of controlling a first energy storage device having SOC characteristic of FIG. 5. to be.

First, the central control unit 400 receives a current output value and SOC value from the plurality of distributed power supplies 100, the first energy storage device 200, and the second energy storage device 300 through the network 900 ( S100). In this case, the central control unit 400 receives current output values from the plurality of distributed power supplies 100, receives the current output values and SOC values from the first energy storage device 200 having SOC characteristics, and has no SOC characteristics. 2 receives the current output value from the energy storage device (300).

The central control unit 400 calculates the load of the microgrid system by using the received current output value and SOC value (S200). At this time, the central control unit 400 calculates the load of the microgrid system by summing the current output values received from the plurality of distributed power supplies 100, the first energy storage device 200 and the second energy storage device 300. .

The central control unit 400 classifies the load amount calculated using the low pass filter into a long period load amount and a short period load amount (S300). At this time, the central control unit 400 classifies the long period load when the calculated load passes the low pass filter. If the calculated load does not pass the low pass filter, the central controller 400 classifies it as a short period load.

When the calculated load amount is classified as a long period load amount (S400; YES), output control of the second energy storage device 300 having no SOC characteristic is performed (S500). Hereinafter, a method of controlling the output of the second energy storage device 300 having no SOC characteristic will be described in detail with reference to FIG. 6.

First, the central controller 400 sets an output value command of the second energy storage device 300 based on the long-term load amount and the SOC value from the first energy storage device 200 (S510). At this time, the central control unit 400 sets the value calculated by summing the SOC value received from the first energy storage device 200 and the classified long period load amount as an output value command of the second energy storage device 300. The central control unit 400 transmits the set output value command to the second energy storage device 300.

If the output value command is greater than or equal to the first load 800 set value and less than or equal to the second load 800 set value (S520; YES), the second energy storage device 300 sets the tidal flow control mode (S522). Here, the set value of the first load 800 is the sum of the minimum output value of the second energy storage device 300 and the amount of power supplied to the power system, and the set value of the second load 800 is the second energy storage device 300. Is the sum of the maximum output value and

As the tidal flow control mode is set, the predetermined power is output from the power system, and the second energy storage device 300 outputs power for the load amount by subtracting the power output from the power system from the load amount (S524). Accordingly, the power supply and demand balance of the microgrid is maintained in the second energy storage device 300 having no SOC characteristic.

If the output value command is less than the first load 800 set value (S540; YES), the second energy storage device 300 sets the UPC first mode (S542). As set to the UPC first mode, the second energy storage device 300 outputs power at the minimum output, and the system power outputs power for the remaining load 800 (S544). As a result, the power supply balance of the microgrid is maintained in the grid power.

If the output value command exceeds the set value of the second load 800 (S560; YES), the second energy storage device 300 sets the UPC second mode (S562). As set to the second mode UPC, the second energy storage device 300 outputs power at maximum output, and outputs power for the remaining load 800 in the power system (S564). As a result, the power supply balance of the microgrid is maintained in the grid power.

When the calculated load is classified as a short period load (S400; NO), output control of the first energy storage device 200 having SOC characteristics is performed (S600). At this time, the first energy storage device 200 performs the output control through the local control by the droop control. Hereinafter, a method of controlling output of the first energy storage device 200 having SOC characteristics will be described in detail with reference to FIG. 7.

An output reference value of the first energy storage device 200 is set based on the calculated load amount (S610). In this case, the first energy storage device 200 sets an output set value including an excess load amount and an insufficient load amount. That is, the first energy storage device 200 sets the control mode of the first energy storage device 200 by comparing the load amount with a set output reference value (that is, excess load and underload) when the calculated load is a short period load. do. The first energy storage device 200 controls the output by PI control of the output of the first energy storage device 200 according to the control mode set.

If the load amount (that is, the short period load amount) is more than the excess load amount or less than the insufficient load amount (S620; YES), the first energy storage device 200 is set to the tidal flow control mode (622). When set to the tidal flow control mode, the power system outputs a predetermined power, and the first energy storage device 200 outputs power for the remaining amount of load 800 except for the output of the power system from the load amount (S624).

If the load amount (that is, the short period load amount) is less than the surplus load amount (S640; YES), the first energy storage device 200 is set to the charge control mode (S642). When the charging control mode is set, the first energy storage device 200 maintains the maximum output charging and outputs power for the remaining load 800 in the power system (S644).

If the load amount (that is, the short period load amount) exceeds the underload amount (S660; YES), the first energy storage device 200 is set to the discharge control mode (S662). When set to the discharge control mode, the first energy storage device 200 maintains the maximum output discharge, and outputs the power to the remaining load 800 in the power system (S664).

Hereinafter, the operation mode of the energy storage devices in the cooperative control system and method of the microgrid energy storage device according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. FIG. 8 is a diagram for describing an operation mode of the second energy storage device 300 having no SOC characteristic. 9 to 11 are diagrams for describing an operation mode of the first energy storage device 200 having SOC characteristics.

8 shows the load 800 and the capacity in consideration The operation mode of the second energy storage device 300 (eg, the fuel cell 360) having no SOC characteristic is illustrated in detail. In general, the second energy storage device 300 having no SOC characteristic (for example, the fuel cell 360 or the distributed power supply 100) has a minimum output power Pdg_min and a maximum output power Pdg_max. At this time, the first load 800 setting value and the second load 800 setting value, which are reference values for setting the control mode of the second energy storage device 300, are calculated using Equations 1 and 2 below. do.

Equation 1

Equation 2

The second energy storage device 300 compares the first load 800 reference value, the second load 800 reference value, and the output value command to set the control mode of the second energy storage device 300 as follows, and the control mode. To output power.

UPC 1st mode: Pdg = 0 if 0 <Pload <Pdg_min

                Pdg_min output when Pdg_min ≤ Pload ≤ Pload_p1

Bird Control Mode (FFC): Pload_p1 <Pload <Pload_p2

UPC Mode 2: Pload_P2 ≤ Pload

That is, when the load amount Pload or the output value command is less than the first load 800 set value Pload_p1, the second energy storage device 300 operates in the UPC first mode. Accordingly, the second energy storage device 300 (fuel cell 360) constantly outputs the minimum output and the remaining load 800 outputs the system power. At this time, when the load amount Pload is less than the minimum output Pdg_min, the second energy storage device 300 is turned off, and the output becomes 0, and power is supplied from the power system.

If the load Pload is greater than or equal to the first load 800 set value Pload_p1 and less than or equal to the second load 800 set value Pload_P2, the second energy storage device 300 operates in the tidal current control mode. Accordingly, the power supply is constantly supplied from the power system by a predetermined amount (ie, contract power), and the power of the remaining load 800 is in charge of the second energy storage device 300.

When the load 800 of the second energy storage device 300 having no SOC characteristic exceeds the capacity of the second energy storage device 300 (that is, the second load 800 is greater than or equal to the set value Pload_P2). In the case), the second energy storage device 300 outputs the maximum output and receives constant power from the associated power system. In this case, the power supply of the remaining load 800 is set to the UPC second mode that is in charge in the associated power system.

9 is a detailed diagram of the operation mode when the power system is connected to the first energy storage device 200 (that is, the battery 280) having SOC characteristics in consideration of the load 800 and capacity.

Charge control (UPC_ch) mode: Pdg = -Pdg_max (charge) when -Pload_p1 <-Pload

Current control (FFC) mode: -Pload_p1 ≤ Pload ≤ + Pload_p2

Discharge control (UPC_dis) mode: Pdg = + Pdg_max (discharge) when + Pload_P2 <Pload

In general, the energy storage device having the SOC (ie, the first energy storage device 200 and the battery 280) does not have a limit of the minimum output power Pdg_min, but there are restrictions on the maximum power power Pdg_max and the SOC. do. In FIG. 9, the (+) load 800 is the underload amount (+ Pload_p2) that the first energy storage device 200 having the SOC should discharge and be in charge of, and the (−) load 800 is the zero load having the SOC. 1 is the surplus load amount (-Pload_p1) that the energy storage device 200 should charge and take charge of.

When operating under surplus load or under underload, it is set in the tidal current control mode to receive or receive a constant power from the power system, and the power supply for the load 800 variation is the first energy storage device 200 having an SOC. In charge of)

 If | Pload | <| Pgrid_FFC (power system output set value) |, the second energy storage device 300 having the SOC charges or discharges the surplus power or the insufficient power. That is, when the load amount Pload exceeds the underload amount + Pload_p2, when the load 800 is large, the second energy storage device 300 having the SOC discharges at the maximum output power (+ Pdg_max) and the remaining load 800 Sets to the discharge control (UPC_dis) mode that receives power from the power system.

 On the contrary, the load 800 is small, or the output of renewable energy is left, and the surplus power exceeds the charging capacity of the distributed power supply 100 (battery 280) having the SOC (that is, the load amount (-Pload) is the excess load amount. If (-Pload_p1) is exceeded, the first energy storage device 200 having the SOC charges to the maximum output power (dg_max) and the power supply of the remaining load 800 is supplied from the associated power system. Mode).

FIG. 10 is a graph of a control operation mode when the first energy storage device 200 having an SOC is connected to a power system, and illustrates a control change according to an output set value Pgrid_FFC of the power system. In FIG. 9, when the output set value is positively supplied with (+), the load_p1 value of the second and third graphs of the graphs 2 and 3 are moved to load_p1`, thereby changing the conversion point of the UPC mode. At this time, if -Pload_p1, -Pdg_max grid_FFC, and if -Pload_p1`, -Pdg_max + Pgrid_FFC. That is, in the case of dg_max <-Pload in which surplus power that the first energy storage device 200 having the SOC has to be more than the capacity of the first energy storage device 200 having the SOC is set to UPC_ch mode, the SOC has the SOC. The first energy storage device 200 is charged to the maximum output (dg_max), the power supply of the remaining load 800 change is supplied from the associated power system. The insufficient power that the first energy storage device 200 having the SOC should be in charge is the same as the first and fourth quadrants of FIG. 8.

 FIG. 11 illustrates a case in which Pgrid_FFC constantly receives (-) power, and the + Pload_p2 value of the first and fourth quadrants of FIG. 9 is moved to + Pload_p2`, thereby changing the conversion point of the UPC mode. At this time, + Pdg_max + Pgrid_FFC for + Pload_p2 and + Pdg_max-Pgrid_FFC for + Pload_p2`.

 Discharge control (UPC_dis) mode in the case of + Pdg_max <+ Pload in which the insufficient power that the first energy storage device 200 having the SOC has to handle is greater than the capacity of the first energy storage device 200 having the SOC. The first energy storage device 200 having the SOC is discharged at the maximum output + Pdg_max, and the remaining load 800 variation is supplied from an associated power system. At this time, the surplus power that the first energy storage device 200 having the SOC should be in charge is the same as the second and third quadrants of FIG. 9.

 The SOC management of the present invention maintains the SOC of the first energy storage device 200 having the SOC without the SOC by using the proportional-integral controller, FIG. 10. It is maintained at the arrow point at. In this step, first, the first energy storage device 200 having the SOC is charged or discharged by droop control with respect to the instantaneous load 800 change. Then, when the SOC of the first energy storage device 200 exceeds the limit range, the second energy storage device 300 without SOC adds or subtracts the output for SOC management. If the output of the second energy storage device 300 without SOC is subject to the output limit, the setting is changed from the tidal flow control mode to the UPC mode, and the second energy storage device 300 without SOC has a constant output as Pfc_max or Pfc_min. Pbtry = 0, the remaining load 800 is powered from the associated power system.

As described above, the cooperative control system and method of the energy storage device for the microgrid divides the amount of variation of the microgrid load 800 into the long period load 800 and the short period load 800 so that the long period load 800 is an SOC. Energy storage device (ie, fuel cell 360), which is slow and dynamic, and the short cycle load 800 is responsible for energy storage device (ie, battery 280) with SOC. By doing so, it is possible to maintain the power supply and demand balance of the micro grid, and to maintain the system power flowing into the micro grid constantly.

In addition, the cooperative control system and method of the energy storage device for the microgrid, the energy storage device is solely responsible for the variation of the load 800 inside the microgrid regardless of time to supply power to the load 800 and vice versa When the output of the device exceeds the load 800 variation, the load 800 variation is taken care of by the power system, and the battery 280 switches to a unit control mode that produces a constant output to maintain the power supply balance, thereby maintaining the microgrid. It is effective to operate stably.

Although a preferred embodiment according to the present invention has been described above, it is possible to modify in various forms, and those skilled in the art to various modifications and modifications without departing from the claims of the present invention It is understood that it may be practiced.

Claims (30)

1. A central controller configured to set an output value command for controlling an output of an energy storage device having no SOC characteristic based on a current output value and an SOC value received from a plurality of distributed power supplies and energy storage devices;

   A first energy storage device for transmitting a current output value and an SOC value to the central controller, and controlling the output by droop control; And

   And a second energy storage device which transmits a current output value to the central control device and controls the output based on an output value command received from the central control device.
2. The method according to claim 1,

   The central control unit,

   A load calculation unit configured to calculate a load of the microgrid system by adding the plurality of distributed power supplies and current output values received from the first energy storage device and the second energy storage device;

   A load amount classifying unit classifying the load amount calculated by the load amount calculating unit into a long period load amount and a short period load amount; And

   And a controller configured to set an output value command based on the long period load amount classified by the load amount classification unit and the SOC value from the first energy storage device, and transmit the output value command to the second energy storage device. Cooperative control system for microgrid energy storage device.
3. The method according to claim 2,

   And the load classifying unit comprises a low pass filter.
4. The method according to claim 3,

   The load amount classification unit,

   And if the load calculated by the load calculation unit passes through the low pass filter, classify the load into a long period load amount.
5. The method according to claim 2,

   The control unit,

   The energy storage device for the microgrid, wherein the SOC value received from the first energy storage device and the long period load amount classified by the load classification unit are set as an output value command of the second energy storage device. Cooperative control system.
6. The method according to claim 1,

   And the first energy storage device includes a battery having SOC characteristics, and the second energy storage device includes a fuel cell having no SOC characteristics.
7. The method according to claim 1,

   The first energy storage device is a cooperative control system of the energy storage device for a micro grid, characterized in that for controlling the output through the local control by the droop control.
8. The method according to claim 1,

   The first energy storage device,

   A reference value setting unit for setting an output reference value of the first energy storage device based on the load amount from the central controller;

   A control mode setting unit configured to set a control mode of the first energy storage device by comparing the load amount with the output reference value when the load amount calculated by the central controller is a short period load amount; And

   And an output control unit for controlling the output of the first energy storage device in accordance with the control mode set by the control mode setting unit.
9. The method according to claim 8,

   The reference value setting unit,

   A cooperative control system for an energy storage device for a microgrid, characterized by setting an output set value including an excess load and an underload.
10. The method according to claim 9,

    The control mode setting unit,

    If the load amount is less than the excess load amount is set to the charge control mode, if the load amount is more than the excess load amount or less than the insufficient load amount is set to the tidal current control mode, and if the load amount exceeds the insufficient load amount is set to the discharge control mode, characterized in that Cooperative control system of energy storage device for microgrid.
11. The method according to claim 10,

    The output control unit,

    When the control mode setting unit is set to the charging control mode, the first energy storage device is controlled to charge at the maximum output, and when the control mode setting unit is set to the tidal current control mode, the load fluctuation amount excluding the power amount preset in the power system. Controlling the first energy storage device to output power for the microgrid, and controlling the first energy storage device to discharge at the maximum output when the control mode setting unit is set to the discharge control mode. Cooperative control system of the device.
12. The method according to claim 1,

    The second energy storage device,

    A control mode setting unit for setting a control mode of the second energy storage device based on an output value command and a load setting value received from the central controller; And

    And an output control unit for controlling the output of the second energy storage device in accordance with the control mode set by the control mode setting unit.
13. The method according to claim 12,

    The control mode setting unit,

    If the output value command is less than the first load setting value, set to UPC first mode, and if the output value command is greater than or equal to the first load setting value and less than or equal to the second load setting value, set to the tidal current control mode, and the output value command is set to the When the second load setting value is exceeded, the microgrid energy storage device for cooperative control system, characterized in that the setting in the UPC second mode.
14. The method according to claim 13,

    The first load setting value is the sum of the minimum output value of the second energy storage device and the power system inflow power amount, and the second load setting value is the maximum output value of the second energy storage device and the power system inflow power amount. Cooperative control system of the energy storage device for a micro grid, characterized in that the sum.
15. The method according to claim 13,

    The output control unit,

    When the control mode setting unit is set to the UPC first mode, and controls the second energy storage device to output power at the minimum output,

    When the control mode setting unit is set to the tidal flow control mode, the control unit outputs the preset power from the power system and outputs the power of the load from the load, subtracting the power output from the power system, from the second energy storage device.

    When the control mode setting unit is set to the UPC second mode, the cooperative control system of the energy storage device for a micro grid, characterized in that for controlling the second energy storage device to output power at the maximum output.
16. The method according to claim 15,

    The output control unit,

    When the UPC mode is set and the output value command is less than the minimum output of the second energy storage device, the output of the second energy storage device is controlled to be 0.

    When the UPC mode is set and the output value command is greater than or equal to the minimum output of the second energy storage device and is less than the first load set value, the second energy storage device is controlled to output at the minimum output energy. Cooperative control system of storage device.
17. Receiving a current output value and an SOC value from the plurality of distributed power supplies, the first energy storage device and the second energy storage device;

    Calculating a load of a microgrid system based on the plurality of distributed power supplies and current output values received from the first energy storage device and the second energy storage device;

    Classifying the calculated load into a long period load and a short period load;

    Setting an output value command of the second energy storage device based on the classified long period load amount and the SOC value from the first energy storage device; And

    And controlling the output of the second energy storage device based on the set output value command.
18. The method according to claim 17,

    In the step of calculating the load amount,

    And calculating a load of the microgrid system by adding the plurality of distributed power supplies and current output values received from the first energy storage device and the second energy storage device.
19. The method according to claim 17,

    In the step of classifying the long period load and the short period load,

    And if the calculated load passes a low pass filter, the load is classified into a long period load amount.
20. The method according to claim 17,

    In the step of setting the output value command,

    And a value calculated by summing the SOC value received from the first energy storage device and the classified long period load amount as an output value command of the second energy storage device. .
21. The method according to claim 17,

    In the controlling of the output of the second energy storage device,

    If the output value command is less than the first load setting value, set to UPC first mode, and if the output value command is greater than or equal to the first load setting value and less than or equal to the second load setting value, set to the tidal current control mode, and the output value command is set to the If the second load setting value is exceeded, the control mode of the microgrid energy storage device, characterized in that the setting in the UPC second mode.
22. The method according to claim 21,

    The first load setting value is the sum of the minimum output value of the second energy storage device and the power system inflow power amount, and the second load setting value is the maximum output value of the second energy storage device and the power system inflow power amount. A cooperative control method for an energy storage device for microgrids, which is a sum value.
23. The method according to claim 21,

    In the controlling of the output of the second energy storage device,

    When the first mode is set to the UPC, the second energy storage device is controlled to output power at a minimum output. When the current control mode is set to the tidal current control mode, the preset power is output from the power system and the power output from the power system. Controlling the second energy storage device to output the power of the load subtracted from the second energy storage device, and outputting power at the maximum output when the UPC is set to the second mode. Cooperative control method of storage device.
24. The method according to claim 21,

    In the controlling of the output of the second energy storage device,

    When the UPC mode is set and the output value command is less than the minimum output of the second energy storage device, the output of the second energy storage device is controlled to be 0.

    When the UPC mode is set and the output value command is greater than or equal to the minimum output of the second energy storage device and is less than the first load set value, the second energy storage device is controlled to output at the minimum output energy. Cooperative control method of storage device.
25. The method according to claim 17,

    And cooperatively controlling the output of the first energy storage device through the local control by the droop control.
26. The method according to claim 25,

    In the controlling of the output of the first energy storage device,

    Setting an output reference value of the first energy storage device based on the calculated load amount;

    Setting the control mode of the first energy storage device by comparing the load amount with the calculated output reference value when the calculated load amount is a short period load amount; And

    And co-controlling the output of the first energy storage device according to the control mode.
27. The method of claim 26,

    In the step of setting the output reference value,

    A cooperative control method for an energy storage device for a microgrid, characterized by setting an output set value including an excess load amount and an underload amount.
28. The method of claim 26,

    In setting the control mode of the first energy storage device,

    If the load amount is less than the excess load amount is set to the charge control mode, if the load amount is more than the excess load amount or less than the insufficient load amount is set to the tidal current control mode, and if the load amount exceeds the insufficient load amount is set to the discharge control mode, characterized in that Cooperative control method of energy storage device for microgrid.
29. The method of claim 26,

    In the controlling of the output of the first energy storage device,

    When the charging control mode is set, the first energy storage device is controlled to charge at the maximum output power. When the charging control mode is set, the first energy storage device is configured to output power for a load fluctuation amount excluding a predetermined power amount in a power system. And controlling the first energy storage device to discharge the device at maximum output when the device is set to the discharge control mode.
30. The method according to claim 17,

    In the step of receiving the current output value and SOC value,

    Receiving current output values from the plurality of distributed power supplies

    Receiving a current output value and SOC value from the first energy storage device having SOC characteristics; And

    And receiving a current output value from the second energy storage device having no SOC characteristic.

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