KR101097459B1 - Building micro-grid system and operation method thereof - Google Patents

Abstract

The present invention operates economically in conjunction with a real-time power plan or a time-varying plan that will be introduced in the future while maintaining the output of renewable energy power to the maximum, and switch to independent operation in case of emergency such as system failure. The present invention relates to a building microgrid system and a driving method for stably supplying power to a building load without power failure.

Description

Building micro-grid system and operation method

The present invention relates to a building microgrid system and a method of operation using a renewable energy source and an energy storage device, and in particular, real-time power to be introduced in the future in conjunction with the system at all times while maintaining the maximum output of the renewable energy source The present invention relates to a building microgrid system and an operation method for supplying electric power stably without a power failure by switching to independent operation in case of an emergency such as a system breakdown and operating economically in connection with a tariff or time-varying variable tariff.

(1) Power supply system for buildings

The power supply system of existing buildings such as hospitals, shopping centers, and public offices is always connected to the grid to supply power, and an emergency engine generator or uninterruptible power supply (UPS) installed in the building in case of an emergency such as a power failure. It takes a way to supply power to some loads through. Regardless of the time of the electricity bill, the system load is being used as much as the building load is needed.

(2) microgrid

In general, microgrid refers to a low voltage distribution system including a distributed power supply and an energy storage device. Basically, it operates in grid-connected operation mode, but normal power supply should be available in independent operation mode caused by system disturbance such as failure of upper system. In addition, it should be possible to maintain a certain level of power quality (voltage, frequency) even when switching modes between each operation mode. The operational goals of general microgrids are: first, maximizing the economic benefits of consumers by maximizing the use of renewable energy and minimizing fossil fuel power; second, improving reliability through continuous power supply without power failure even in the event of failure of upper system; Quality improvement through stable maintenance of system frequency and voltage.

(3) Consumer power plan

Contract types are classified into residential power, general power, educational power, industrial power, agricultural power, street light, backup power, and temporary power, depending on the electricity use of the contract. Korea's electricity tariff system is divided into six types of residential, general, industrial, educational, agricultural, and streetlights, depending on the purpose of using electricity. The electricity bill for the category is fixed. As shown in FIG. 1, a maximum difference rate of 3.8 times is applied to an industrial consumer of 300 kW or more and a general consumer of 1000 kW or more depending on season and time. In the future, in view of the efficient use of resources such as the reduction of the new investment cost of electric power facilities and the reduction of electric bills through the efficient use of facilities, these hourly rates are expected to be expanded to almost all customers and become more fragmented.

Accordingly, the present invention is to solve the above-mentioned problems, the object of the present invention is to construct a microgrid system for buildings in a building, and to be introduced in the future in conjunction with the system at any time while maximizing the output of renewable energy power source It operates economically in conjunction with the real-time electricity rate plan or the time-varying rate plan, and provides a microgrid system and operation method for building that can supply power stably without power failure by switching to independent operation in case of an emergency such as system breakdown. There is.

First, to summarize the features of the present invention, the operation method of the building microgrid system according to an aspect of the present invention for achieving the object of the present invention as described above, maintaining the maximum renewable energy power output and the power bill time zone Operation method of building microgrid system to provide stable power to buildings even in case of power failure and operate economically by interlocking. If the capacity of the device (commercial ESS) is larger than the minimum capacity, the difference between the renewable energy power output and the building load does not receive power from the power system, so as to meet the supply and demand for the building load using the commercial ESS. A first mode driving step of charging a battery and discharging charging power to the building load; During operation, when the power rate is low (light load time zone) or the output of the renewable energy power is greater than the building load, and the commercial ESS is not fully charged, power is supplied to the building load using the commercial ESS. And a second mode operation step of charging the remaining output of the renewable energy power source. And during operation, when the capacity of the commercial ESS becomes smaller than the minimum capacity in the first mode operation step, or when the commercial ESS is fully charged in the second mode operation step, the output of the renewable energy power source is If the building load is greater than the building load, the output of the renewable energy power supply is supplied to the power system by the difference, and if the output of the renewable energy power supply is less than the building load, the building receives power from the power system by the difference. And a third mode operation step of supplying power to the load.

The amount of power charged by the commercial ESS in the second mode operation step is expressed by a formula, (maximum load or medium load time required load amount)-(light load time zone renewable energy power supply) + (light load time zone building load amount). Is determined.

In the operation method of the building microgrid system, when a failure occurs in the power system during operation, the system is switched to a non-connected state with the power system and replaces the commercial ESS to replace an emergency energy storage device (emergency ESS). And a fourth mode operation step of controlling the output of the renewable energy power source to provide power to the building load at a voltage and frequency within a predetermined range.

The operation method of the building microgrid system is to supply power to the building load using only the emergency ESS without using the output of the renewable energy power source when the emergency ESS does not maintain the condition of the voltage and frequency. It further comprises a step.

In the operation method of the building microgrid system, if the duration of the normal state of the system after the power system is restored exceeds the reference time, the emergency ESS is the magnitude, frequency, and phase of the connection point voltage connected to the power system After matching the voltage, magnitude, and phase of the power system, respectively, the fifth mode operation step of connecting the power system and replacing the emergency ESS, the commercial ESS supplies power to the building load is further performed. Include.

In addition, the building microgrid system according to another aspect of the present invention, the building microgrid for maintaining the output of renewable energy power to the maximum, driving economically in conjunction with the electricity tariff time, and supplying stable power to the building even in the event of power failure A grid system, comprising: an energy management system for controlling power supply to a building load using a renewable energy power source and a commercial energy storage device (commercial ESS), wherein the energy management system is a time zone having a high power rate, and When the building load is greater than the output of the renewable energy power source and the capacity of the commercial ESS is greater than the minimum capacity, the new building is supplied with the commercial ESS to meet the supply and demand for the building load without receiving power from the power system. The difference between the renewable energy power output and the building load is charged and the charging power is increased. When the first mode operation is controlled to discharge to the building load, and during operation, when the power bill is low (light load time zone) or the output of the renewable energy power is larger than the building load, and the commercial ESS is not fully charged, The second mode operation is controlled to supply power to the building load by using the commercial ESS and to charge the remaining output of the renewable energy power source, and the capacity of the commercial ESS becomes smaller than the minimum capacity during the first mode operation. In case that the commercial ESS is fully charged during the second mode operation, if the output of the renewable energy power is greater than the building load, the output of the renewable energy power is supplied to the power system by a corresponding difference. When the output of the renewable energy power source is less than the building load, the building receives power from the power system by the corresponding difference. And it controls the third operation mode to supply a power up and down.

The energy management system, when a failure occurs in the power system during operation, switch to a non-connected state with the power system, and replace the commercial ESS by using the emergency energy storage device (emergency ESS) by using the new renewable By controlling the output of the energy power source to control the fourth mode operation so that a single operation for supplying power to the building load in a range of voltage and frequency is made.

The energy management system controls to supply power to the building load with only the emergency ESS without using the output of the renewable energy power source when the emergency ESS does not maintain the condition of the voltage and frequency.

The energy management system, if the duration of the normal system exceeds the reference time after the power system is restored, the magnitude, frequency, and phase of the connection point voltage of the emergency ESS is connected to the power system, respectively, After controlling to match the magnitude, frequency, and phase of the voltage, the fifth mode operation is controlled so that the commercial ESS supplies power to the building load in association with the power system and replaces the emergency ESS.

According to the building microgrid system and operation method according to the present invention, it is also configured as a building microgrid system in a consumer building, such as public institutions, commercial, residential use, carbon emissions using a renewable energy power source and energy storage device To maximize the supply and demand of buildings by maximizing the use of new renewable energy sources without electricity, and to save electricity from the power system at the time when the electricity bill is low, and to use it at the time when the electricity bill is expensive, to operate in a manner that minimizes the cost. The building can provide stable power to the load while maximizing the use of renewable energy sources.

In addition, by powering itself apart from the system even in the event of a power system failure, it is possible to increase the reliability of power supply by operating without power failure even in case of emergency such as system failure.

1 is a table showing the difference between the general seasonal and hourly industrial / general electricity rates.
2 is a block diagram of a building microgrid system according to an embodiment of the present invention.
FIG. 3 is a table illustrating operation modes of the building microgrid system of FIG. 2.
4 is a flowchart illustrating operation of a building microgrid system according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. Like reference numerals in the drawings denote like elements.

2 is a block diagram of a building microgrid system 100 according to an embodiment of the present invention.

2, the building microgrid system 100 according to an embodiment of the present invention, renewable energy power source 110, commercial energy storage system (Energy Storage System) (commercial ESS) 120, emergency Energy Storage (Emergency ESS) 130, Static Transfer Switch (STS) 140, Switch 141, Automatic Load Transfer Switch (ALTS) 150 and Energy Management System ( 160).

Renewable energy power source 110 is a power generation device or system using a renewable energy source, such as solar, solar, tidal, or wind power, tidal power, wind speed regardless of the load of the building, grid connection, and the operating state of other components Or operate to produce the maximum output that can be obtained according to weather conditions such as solar radiation.

Commercial energy storage device (commercial ESS) 120 is to supply a stable power to the load of the building through the discharge while the building load is connected to the power system at all times, or to secure the required amount of electricity by charging at a low time period As the charge / discharge energy storage device, various forms such as a secondary battery, a superconducting storage device, a fly wheel, a supercapacitor, and the like may be utilized. In addition, these storage devices may be used singly or in combination of two or more.

The emergency energy storage device (emergency ESS) 130 is a charge / discharge energy energy storage device for supplying stable power to a building load when operating independently without being connected to the power system in an emergency such as a power failure of the power system. Various forms of batteries, superconducting storage devices, fly wheels, supercapacitors, etc. may be utilized. Again, these storage devices can be used singly or in combination of two or more.

The stationary ablation switch (STS) 140 determines whether the power system is broken and automatically shuts down the building microgrid system 100 within one cycle (one cycle of supply frequency) from the power system and recovers the power system. After that, it corresponds to an intelligent switch that serves to physically reconnect the building microgrid system 100 to the power system. The stationary ablation switch (STS) 140 transmits a cutoff signal to the energy management system 160 after the shutdown from the power system, and accordingly controls the energy management system 160 so that the switch 141 is turned off. Upon reconnection after the system is restored, the switch 141 may be turned on by receiving the command of the energy management system 160 to perform re-input of power from the power system to the commercial energy storage device (commercial ESS) 120.

The automatic load changeover switch (ALTS) 150 is interlocked with the building system in the building microgrid system 100, so that the power from the power system or the renewable energy power source 110 is commercial energy storage device 120 or emergency use. It is delivered to the energy storage device 130 to automatically switch the physical connection to be supplied to the building load.

The energy management system 160 monitors the overall operating state of the building microgrid system 100 and sends operation commands to each component of the system 100 to manage the operation of the entire system 100. Each component of the energy management system 160 and the system 100 is connected to each other by communication, and basically, each component is configured to maintain a certain level or higher power quality during mode operation or mode switching (see FIGS. 3 and 4). It monitors and controls the output and state of the elements, and commands the output and operation states to each component for optimal operation of the system 100.

FIG. 3 is a table illustrating operation modes of the building microgrid system of FIG. 2.

In order for the building microgrid system 100 to minimize the electric bill of the building and to stably supply power even in the event of a power failure of the power system, the energy management system 160 has a grid connection, load size, and energy storage. The operation control mode of the system 100 is divided into five types according to the operation state of the devices 120 and 130 as shown in FIG. 3.

The renewable energy power source 110 operates to produce the maximum output that can be obtained regardless of the operation mode for economical operation, operation strategy and commercial energy storage device (commercial ESS) 120, emergency energy storage device of each operation mode. (Emergency ESS) 130, the stop type ablation switch (STS) 140, the operation and connection of the automatic load switching switch (ALTS) 150 is as follows.

First, the first operation mode is a driving strategy mode of the maximum load or the medium load time zone as shown in FIG. 3, which is expensive when the power system is linked, and the commercial energy storage device (commercial ESS) 120 is a building and a power system. The power of the connected connection point (the point where the system and the power system are connected) is controlled by the command value transmitted by the energy management system 160. In this case, the command value from the energy management system 160 is set to 0 to receive power from the power system, and the supply and demand for the building load is adjusted using the power charged in the commercial energy storage device (commercial ESS) 120. This can reduce the power usage fee. The stationary ablation switch (STS) 140 maintains a connection state with the power system, and the automatic load switching switch (ALTS) 150 maintains the mode connected to the commercial energy storage device (commercial ESS) 120.

Next, the second driving mode is the driving strategy mode in the light load time zone as shown in FIG. Here, the commercial energy storage device (commercial ESS) 120 is charged from the power system as much as the amount of power required to operate in the first operation mode during the peak load or the medium load time. At this time, the amount of power charged by the commercial energy storage device (commercial ESS) 120 is determined by [Equation 1]. The stationary ablation switch (STS) 140 maintains a connection state with the power system, and the automatic load switching switch (ALTS) 150 maintains the mode connected to the commercial energy storage device (commercial ESS) 120.

[Equation 1]

(Required load during maximum load or medium load)-(renewable energy supply in light load) + (building load in light load)

In addition, the third operation mode is a mode in which the energy storage devices 120 and 130 do not operate during the linked operation with the power system, and operate only so that the renewable energy power source 110 outputs the energy storage devices 120. 130) is a driving strategy mode when the battery is fully charged and cannot be charged anymore, or is fully discharged and cannot be discharged anymore. In this case, when the output of the renewable energy power source 110 is greater than the load of the building, the output of the renewable energy power source 110 is supplied to the power system by the difference, and the output of the renewable energy power source 110 is If it is less than the load, the power is supplied from the power system to the load of the building by the difference. The stationary ablation switch (STS) 140 maintains a connection state with the power system, and the automatic load switching switch (ALTS) 150 maintains the mode connected to the commercial energy storage device (commercial ESS) 120.

In addition, the fourth operation mode is a mode in which a failure occurs in the power system and physically cuts power from the power system and operates independently. In this case, since the direct control of the output of the renewable energy power source 110 is not possible, the emergency energy storage device (emergency ESS) 130 is responsible for the supply and demand imbalance between the output of the renewable energy source 110 and the building load through the load tracking operation. By maintaining the voltage and frequency of the system 100 to be operated independently in a stable range. The stationary ablation switch (STS) 140 switches to a non-connected state at the moment of power system power outage, and the automatic load switching switch (ALTS) 150 is connected to an emergency energy storage device (emergency ESS) 130. Keep it.

Finally, in the fifth operation mode, if the cause is eliminated after the failure of the power system and the power system is restored, the fifth operation mode uses the magnitude, frequency, and phase angle of the voltage of the building microgrid system 100 to reconnect to the power system. Perform a resynchronization process to match those in the system and, when matched, perform a physical reconnection with the power system. In the fifth operation mode, when a reconnection signal is received from the energy management system 160, the emergency energy storage device (emergency ESS) 130 performs this resynchronization operation. Such a re-synchronization is connected to the power system through the momentary stop switch (STS) 140, automatic load switching switch (ALTS) 150 is a commercial energy storage in the emergency energy storage device (emergency ESS) (130) Switch to the mode of connection to the device (commercial ESS) 120.

Hereinafter, the operation of the microgrid system 100 for a building according to an embodiment of the present invention, which operates in five modes as shown in FIG. 3, will be described in detail with reference to the operation control flowchart of FIG. 4. The building microgrid system 100 determines each mode based on the control flowchart as shown in FIG. 4, and basically maintains the output of the renewable energy power source 110 as much as possible, and stores the energy storage devices according to the power rate time slot ( 120, 130) economically charging and discharging, so that the power supply is continuously and stably supplied to the building load during operation of each mode or switching modes.

Referring to FIG. 4, which of the various operation modes is operated in the building microgrid system 100 is determined as shown in the flowchart shown in FIG. 4. Based on this method, the energy management system 160 Provide necessary operating instructions for each component. In the initial state, the instantaneous stop mode switch (STS) 140 maintains the linkage state with the power system, and the automatic load changeover switch (ALTS) 150 connects the mode to the commercial energy storage device (commercial ESS) 120. Renewable energy power source 110 generates a maximum output (S410). First, the energy management system 110 determines whether the power system is operating without failure, and if it is normal, determines whether the power bill is a high time zone (maximum load or medium load time zone) (S411).

At this time, when the power bill is high time period (maximum load or medium load time zone) (S412), the energy management system 110 is the output (power amount) of the renewable energy power source 110 and the building load (power amount consumed in the load of the building). ) Are compared (S413). Since the building load is greater and the capacity of the commercial energy storage device (commercial ESS) 120 is larger than the minimum capacity (a certain minimum capacity which is a reference required for operation) (S414), the system 100 enters the first operation mode. By setting the command value from the energy management system 160 to 0 to receive power from the power system, and supply and demand for the building load using the power charged in the commercial energy storage device (commercial ESS) 120. As a result, the power usage fee can be reduced (S420). In this case, the commercial energy storage device (commercial ESS) 120 may charge as much as the difference between the output of the renewable energy power source 110 and the building load, and discharge the charging power to the load without using the power of the power system. Under the control of the energy management system 110 in the first mode of operation, the stationary ablation switch (STS) 140 maintains a connection with the power system, and the automatic load switching switch (ALTS) 150 is a commercial energy storage device. Maintain a mode that is connected to (commercial ESS) 120.

However, if the commercial energy storage device (commercial ESS) 120 is completely discharged during operation in the first operation mode and the remaining capacity becomes smaller than the minimum capacity, the system 100 switches to the third operation mode, where the renewable energy Only the power source 110 generates an output (S430). In the third operation mode, when the output of the renewable energy power source 110 is greater than the load of the building, the output of the renewable energy power source 110 is supplied to the power system by the difference, and the output of the renewable energy power source 110. If it is less than the load of the building, the power is supplied from the power system to the load of the building by the difference. At this time, according to the control of the energy management system 110, the stationary ablation switch (STS) 140 maintains the connection state with the power system, the automatic load switching switch (ALTS) 150 is a commercial energy storage device (commercial ESS) Maintain a mode that leads to 120.

In step S413, when the output of the renewable energy power source 110 is greater than the building load (S413), the energy management system 110 determines whether or not the buffer of the commercial energy storage device (commercial ESS) 120 is fully buffered state. If not, switch to the second operation mode, supply the power to the building load to the commercial energy storage device (commercial ESS) 120, and outputs the output of the renewable energy power source 110 remaining commercial energy storage device (commercial ESS) 120 Charge to (S440). After the full charge is switched to the third driving mode (S430).

The amount of power charged by the commercial energy storage device (commercial ESS) 120 in the second operation mode is determined by [Equation 1]. At this time, under the control of the energy management system 110, the stationary ablation switch (STS) 140 maintains the linkage state with the power system, and the automatic load switching switch (ALTS) 150 is a commercial energy storage device (commercial ESS) Maintain a mode that is connected to 120).

In the step S412, in the case of a low power time zone (light load time zone), immediately determine the state of charge of the commercial energy storage device (commercial ESS) 120 to switch to the second operation mode if not fully charged (S440), When the transition to the third operation mode is switched to operate (S430).

Thereafter, during operation in each operation mode, when a failure occurs in the power system in step S411, the system 100 is switched to the fourth operation mode under the control of the energy management system 110, the stationary ablation switch (STS) 140 is switched to open in a non-connected state at the moment of power system blackout, automatic load switching switch (ALTS) 150 maintains the mode connected to the emergency energy storage device (emergency ESS) (130) (S450) ). In this case, since the direct control of the output of the renewable energy power source 110 is not possible, the emergency energy storage device (emergency ESS) 130 is responsible for the supply and demand imbalance between the output of the renewable energy source 110 and the building load through the load tracking operation. By maintaining the voltage and frequency of the system 100 to be operated independently in a stable range. That is, while adjusting the imbalance between the load of the building separated from the power system and the output of the renewable energy power source 110, the power is adjusted so that the output of the renewable energy power source 110 is supplied to the building load at a voltage and frequency maintained in a certain range. .

If the emergency energy storage device (emergency ESS) 130 does not meet the voltage and frequency requirements, the energy management system 110 turns off the switch 141 to stop the output of the renewable energy power source 110. In addition, only the emergency energy storage device (emergency ESS) 130 supplies power to the load to smoothly maintain voltage and frequency (S452).

The energy management system 110 continuously monitors the state of the power system, and after the system is restored (S453), the duration of the normal state of the system is the reference time (5 minutes is the standard suggested by KEPCO in the case of distributed power). The operation is maintained in the fourth operation mode until the operation time is exceeded, and when the duration time of the normal system exceeds the reference time (S454), the operation is switched to the fifth operation mode and resynchronization operation is attempted (S460). At this time, the emergency energy storage device (emergency ESS) 130 makes the magnitude, frequency, and phase of the connection point voltage match with the magnitude, frequency, and phase of the power system voltage, respectively, and if it matches, the energy management system 110 stops the switch. Turn on (STS) 140 to be linked to the power system and the automatic load changeover switch (ALTS) 150 from the emergency energy storage device (emergency ESS) 130 to the commercial energy storage device (commercial ESS) 120 Switch to the connected mode to allow the commercial energy storage device (commercial ESS) 120 to supply power to the building load (S461).

As described above, the present invention has been described by way of limited embodiments and drawings, but the present invention is not limited to the above embodiments, and those skilled in the art to which the present invention pertains various modifications and variations from such descriptions. This is possible. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the claims below but also by the equivalents of the claims.

110: renewable energy power source
120: Commercial Energy Storage System (Commercial ESS)
130: emergency energy storage device (emergency ESS)
140: static transfer switch (STS)
141: switch
150: Automatic Load Transfer Switch (ALTS)
160: energy management system

Claims (10)

When the building load is greater than the output of the renewable energy source and the capacity of the commercial energy storage device (commercial ESS) is greater than the minimum capacity at the maximum load or the medium load time period divided by the electric charge, power is not received from the power system. And a first mode driving step of charging the electric power by the difference between the renewable energy power output and the building load using the commercial ESS, and discharging the charging power to the building load in order to meet the supply and demand for the building load.
During operation, when the light load time zone divided by the electricity bill or when the output of the renewable energy power is greater than the building load and the commercial ESS is not fully charged, the renewable energy power supply remaining to supply the power to the building load. A second mode operation step of charging the output of the power using the commercial ESS;
During operation, when the capacity of the commercial ESS becomes smaller than the minimum capacity in the first mode operation step, or when the commercial ESS is fully charged in the second mode operation step, the output of the renewable energy power source is generated in the building. When the load is greater than the load, the output of the renewable energy power is supplied to the power system by the corresponding difference, and when the output of the renewable energy power is smaller than the building load, the power is received from the power system by the difference. A third mode operating step of supplying power to the furnace;
During operation, when a failure occurs in the power system, the power system switches to a non-connected state with the power system, and controls the output of the renewable energy power source by using an emergency energy storage device (emergency ESS) in place of the commercial ESS. A fourth mode operation step of performing a single operation of supplying power to the building load at a voltage and frequency in a predetermined range; And
After the power system is restored, if the duration of the normal state of the system exceeds the reference time, the emergency ESS has the magnitude, frequency, and phase of the connection point voltage connected to the power system, respectively. And a fifth mode operation step in which the commercial ESS supplies electric power to the building load by connecting with the power system and replacing the emergency ESS after matching with the phase.
Driving method of a building microgrid system comprising a. The method of claim 1,
The amount of power charged by the commercial ESS in the second mode operation step is
Equation
(Required load during maximum load or medium load)-(renewable energy supply in light load) + (building load in light load)
A method of operating a microgrid system for buildings, characterized in that determined by. delete The method of claim 1,
Supplying power to the building load with only the emergency ESS without using the output of the renewable energy power source when the emergency ESS cannot maintain the condition of the voltage and frequency.
Method of driving a microgrid system for buildings, characterized in that it further comprises. delete A renewable energy source and a commercial energy storage device (commercial ESS) using an energy management system for controlling the power supply to the building load, the energy management system,
When the building load is greater than the output of the renewable energy power source and the capacity of the commercial ESS is greater than the minimum capacity at the maximum load or the medium load time period divided by the electric charge, the electric power is not received from the power system. In order to meet the demand for building load, the first mode operation is controlled to charge the difference between the renewable energy power output and the building load by using the commercial ESS and discharge the charging power to the building load.
During operation, when the light load time zone divided by the electricity charge or the output of the renewable energy power is greater than the building load, and the commercial ESS is not fully charged, the renewable energy power source remaining after supplying power to the building load. To control the second mode of operation to charge the output of the battery using the commercial ESS;
When the capacity of the commercial ESS becomes smaller than the minimum capacity during the first mode operation, or when the commercial ESS is fully charged during the second mode operation, when the output of the renewable energy power source is greater than the building load, Supply the output of the renewable energy power to the power system by a difference, and if the output of the renewable energy power is less than the building load, receive power from the power system by the difference to supply power to the building load. To control the third mode operation,
During operation, when a failure occurs in the power system, the power system switches to a non-connected state with the power system, and controls the output of the renewable energy power source by using an emergency energy storage device (emergency ESS) in place of the commercial ESS. To control the fourth mode of operation so that a single operation of supplying power to the building load is performed at a voltage and frequency within a predetermined range.
After the power system is restored, if the duration of the normal state of the system exceeds the reference time, the magnitude, frequency, and phase of the connection point voltage at which the emergency ESS is connected to the power system are respectively the magnitude, frequency, and phase of the voltage of the power system. And controlling to coincide with the phase, and in connection with the power system, controlling the fifth mode of operation so that the commercial ESS supplies power to the building load by replacing the emergency ESS. . The method of claim 6,
The amount of power charged by the commercial ESS during the second mode operation is
Equation
(Required load during maximum load or medium load)-(renewable energy supply in light load) + (building load in light load)
Building microgrid system, characterized in that determined by. delete The method of claim 6,
The energy management system,
When the emergency ESS does not maintain the conditions of the voltage and frequency, the building microgrid system for controlling to supply power to the building load with only the emergency ESS without using the output of the renewable energy power source. . delete

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