KR102358178B1 - Electric charging system and method linking wind power generation and solar power generation - Google Patents

Abstract

The present invention is a wind power generation and photovoltaic power generation linkage electric charging system that stabilizes the electric power of the system, which varies according to the charging amount and load of an EV (Electric Vehicle) and the amount of generation of new and renewable energy, through the voltage control of the ESS (Energy Storage System). and methods. Wind power generation and photovoltaic power generation-related electric charging system according to an embodiment of the present invention is to measure the voltage value and current value of the system that varies according to the amount of charge and load of EVC (Electric Vehicle Charging) and the amount of power generation of the renewable energy power source Using the voltage and current measurement unit and the measured voltage and current values of the system to calculate the line impedance of the system, based on the calculated line impedance, the system voltage measured in real time by the voltage and current measurement unit is used. and an arithmetic unit for calculating a compensation voltage of an Energy Storage System (ESS) for stabilizing the voltage. In addition, a determination unit that monitors the voltage of the system measured by the voltage and current measurement unit in real time to determine whether the voltage of the system is within a voltage reference range (between the upper limit voltage and the lower limit voltage), and the system according to the determination result of the determination unit and a charge/discharge control unit that controls the ESS to provide a compensation voltage to the system in order to stabilize the voltage of the system when the voltage is not within the voltage reference range.

Description

Electric charging system and method linking wind power generation and solar power generation

The present invention relates to a wind power generation and photovoltaic power generation-linked electric charging system and method, wherein the electric power of the system that varies according to the charging amount and load of an EV (Electric Vehicle) and the amount of generation of new and renewable energy is converted into an ESS (Energy Storage System) It relates to a wind power generation and solar power generation linked electric charging system and method for stabilizing through voltage control.

In general, an ESS (Energy Storage System) is a device that improves the efficiency of power use by storing generated electricity in a storage device such as a battery and supplying power when needed.

Such ESS stores electricity generated through new and renewable energy such as wind power generation or solar power generation, or stores electricity transmitted from a power plant in a battery at night when power consumption is low, and can be used during the daytime when power consumption is relatively high. provide so that

At this time, in order to efficiently operate the ESS, it is necessary to control the ESS by reflecting the state of charge (SOC), which is the state of charge or the charge ratio of the battery. Considering the rated capacity of the battery, if the battery is operated to be fully discharged with an SOC of 0% or fully charged with an SOC of 100%, the battery life will be reduced. In addition, since there is a risk of fire when the battery is overcharged, the SOC is not operated in the 0-100% range, but operates in a specific range.

On the other hand, when the low-voltage distribution line of the system is operated including the renewable energy power source, the voltage of the system drops or rises depending on the amount of charge of the EV (Electric Vehicle) and the amount of power generation of the renewable energy power source.

For example, when new and renewable energy is generated, the system voltage rises due to the reverse current, and when the amount of charge and load usage of an EV (Electric Vehicle) increases, the system voltage decreases.

Therefore, in order to stably use the voltage of the system, it is necessary to stabilize the electric power of the system, which varies according to the amount of charge and load of an electric vehicle (EV), and the amount of generation of new and renewable energy.

Republic of Korea Patent Registration No. 10-1956232 (March 08, 2019 Announcement)

Therefore, the present invention solves the disadvantages of the prior art, and the purpose of the present invention is to stabilize the electric power of the system that varies according to the amount of charge and load of an EV (Electric Vehicle) and the amount of generation of new and renewable energy. In addition, the purpose is to efficiently operate the ESS (Energy Storage System).

A wind power generation and photovoltaic power generation-related electric charging system according to an aspect of the present invention for achieving this technical task includes a voltage and current measurement unit, a calculation unit, a determination unit, a charge/discharge control unit, and a storage unit. The voltage and current measurement unit measures the voltage value and current value of the system, which is changed according to the amount of charge and load of EVC (Electric Vehicle Charging) and the amount of power generation of the renewable energy power source.

In addition, the calculating unit calculates the line impedance of the system using the measured voltage and current values of the system, and uses the system voltage measured in real time by the voltage and current measurement unit based on the calculated line impedance to the system voltage. Calculate the compensation voltage of the ESS (Energy Storage System) to stabilize the

In addition, the determination unit monitors the voltage of the system measured by the voltage and current measurement unit in real time to determine whether the voltage of the system is within a voltage reference range (between the upper limit voltage and the lower limit voltage). When the voltage of the system is not within the voltage reference range according to the determination result of the determination unit, the charge/discharge control unit controls the ESS to stabilize the voltage of the system and provides a compensation voltage to the system.

In addition, in the wind power generation and solar power generation-linked electric charging method according to another aspect of the present invention, the voltage and current measurement unit is changed according to the amount of charge and load of EVC (Electric Vehicle Charging) and the amount of power generation of renewable energy sources. Step of measuring the voltage and current of the system in real time (S10), and extracting the maximum allowable current in each section of the system and the line impedance up to the corresponding section based on the voltage and current values of the system measured by the operation unit ( S20).

In addition, the operation unit extracts the voltage fluctuation range of the ESS based on the average maintenance voltage and the system accommodating capacity stably maintaining the ESS or EVC installation stage (S30), and the operation unit uses the voltage fluctuation width of the grid voltage and extracting the upper limit voltage and the lower limit voltage that are the holding ranges (S40).

In addition, the step (S50) of determining whether the system voltage is within a voltage reference range between the upper limit voltage and the lower limit voltage by a determination unit monitoring the system voltage measured by the voltage and current measuring unit in real time (S50); Step (S60) of calculating the compensation voltage of the ESS for stabilizing the voltage of the system by the operation unit when it is not within the voltage reference range (S60) and the charge/discharge control unit controlling the ESS to compensate the compensation voltage calculated by the operation unit to the system (S60) S70).

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As described above, the wind power generation and photovoltaic power generation-linked electric charging system and method according to the present invention converts the electric power of the system that varies according to the electric vehicle (EV) charge amount and load amount and the generation amount of new and renewable energy to ESS (Energy). It has the effect of stabilizing it through the voltage control of the storage system. In addition, there is an effect that the ESS can be operated efficiently by controlling the voltage of the ESS based on the SOC (State of Charge).

1 is a block diagram showing a wind power generation and solar power generation-linked electric charging system according to an embodiment of the present invention.
2 is a block diagram illustrating a wind power generation and solar power generation-linked electric charging system according to an embodiment of the present invention.
3 is a diagram illustrating the characteristics of line impedance according to changes in voltage and current of a system.
4 is a view showing the voltage state of the system according to the ESS control of the present invention.
5A and 5B are diagrams showing the load current of the system according to the ESS control of the present invention.
6 is a diagram showing in detail the voltage of the system according to the charging and discharging of the ESS.
7 is a diagram illustrating charging of the ESS by applying the voltage compensation range margin.
8 is a view showing the charging and discharging operation state of the ESS according to the voltage state of the system.
9 is a diagram illustrating a State of Charge (SOC) for operation of an ESS.
10A and 10B are diagrams illustrating the operation of the ESS according to the voltage state for each section of the system.
11 is a diagram illustrating a case in which the SOC of the ESS is out of an appropriate maintenance range (SOR).
12 is a flowchart illustrating a wind power generation and solar power generation-linked electric charging method according to an embodiment of the present invention.
13 is a diagram illustrating an operation procedure of an ESS according to an embodiment of the present invention.

Hereinafter, with reference to the accompanying drawings, the embodiments of the present invention will be described in detail so that those of ordinary skill in the art to which the present invention pertains can easily implement them. However, the present invention may be embodied in several different forms and is not limited to the embodiments described herein. And in order to clearly explain the present invention in the drawings, parts irrelevant to the description are omitted, and similar reference numerals are attached to similar parts throughout the specification.

Throughout the specification, when a part "includes" a certain element, it means that other elements may be further included, rather than excluding other elements, unless otherwise stated. In addition, terms such as “…unit”, “…group”, and “…module” described in the specification mean a unit that processes at least one function or operation, which is implemented by hardware or software or a combination of hardware and software. can be

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

Like reference numerals in each figure indicate like elements.

1 is a configuration diagram showing a wind power generation and photovoltaic power generation linkage electric charging system 10 according to an embodiment of the present invention, Figure 2 is a wind power generation and photovoltaic power generation linkage electric charging system according to an embodiment of the present invention A block diagram illustrating the system 10 .

In general, the voltage of the system 20 is changed by the current magnitude having a variable value and the line resistance having a fixed value. ), when a reverse current flows toward the grid 20, the voltage rises.

Therefore, the wind power generation and solar power generation linked electric charging system 10 and method according to this embodiment are the charging amount and load of the EVC (Electric Vehicle Charging) 50 through the control of the ESS 40 and Power is stabilized by maintaining the voltage of the system 20, which is changed according to the amount of power generation of the renewable energy 30, within a certain range.

That is, the wind power generation and photovoltaic power generation-linked electric charging system 10 and method is the ESS (40) in order to stabilize the power of the low voltage distribution system (20) when the voltage of the system (20) is less than or equal to a certain value. ) performs a charging or discharging operation.

As shown in FIG. 1 , in the wind power generation and solar power generation linked electric charging system 10 , the ESS 40 is installed in the system 20 to stabilize the voltage of the system 20 through the control of the ESS 40 . can do.

At this time, the system 20 may be operated in connection with a renewable energy power source 30 or EVC (Electric Vehicle Charging) 50 as shown in FIG. 1 . In addition, the renewable energy power source 30 may include wind power generation 31 and solar power generation 32 .

In addition, the wind power generation and solar power generation-linked electric charging system 10 is the system 20 by the amount of charge and the load of the EVC (Electric Vehicle Charging) 50 or the amount of power generation of the new and renewable energy 30 . When the voltage is changed, the voltage of the system 20 can be maintained within a certain range by charging or discharging the voltage through the ESS 40 by the amount of the voltage out of the limit capacity of the system 20 .

The wind power generation and solar power generation-linked electric charging system 10 may include a voltage and current measurement unit 110 , a calculation unit 120 , a determination unit 130 , a charge/discharge control unit 140 , and a storage unit 150 . have.

The voltage and current measurement unit 110 measures a voltage value and a current value of the system 20 . That is, the voltage and current measurement unit 110 is the voltage value and current of the system 20 that varies according to the amount of charge and load of the EVC (Electric Vehicle Charging) 50 and the amount of power generation of the renewable energy power source 30 . Measure the value.

In addition, the calculating unit 120 calculates a line impedance for determining the charge/discharge voltage of the ESS 40 in order to stabilize the voltage of the system 20 . In addition, the operation unit 120 from the pole transformer 21 of the system 20 to the end section in which the ESS 40 is installed, the voltage characteristic at the time of heavy load and the voltage characteristic according to the maximum amount of power generation of the renewable energy power source 30 After analyzing the maximum allowable current of the system (20) is extracted.

3 is a diagram showing the characteristics of line impedance according to voltage and current changes of the system 20 .

In general, the voltage of the system 20 is changed by a current magnitude having a variable value and a line resistance having a fixed value. At this time, the voltage drops when the current of the load flows a lot, and rises when the flow of current is small or when the reverse current flows to the grid 20 by the renewable energy power source 30 .

Therefore, in order to implement voltage stabilization capable of maintaining the voltage of the system 20 within a predetermined range, it is important to calculate the line impedance having a fixed value. To this end, the wind power generation and photovoltaic power generation linked electric charging system 10 according to an embodiment of the present invention determines the line impedance (Z _n ) by the voltage (U) and the passing current (I _ci ) on the established line. suggest a way

That is, the calculating unit 120 according to the embodiment of the present invention uses the following [Equation 1] to the line impedance ( Z _n ) can be calculated.

[Equation 1]

는 계통(20)의 주상변압기(21) 2차측 전압이고,

는 ESS(40)의 운용 전 ESS(40) 또는 EVC(50) 설치 위치의 계통(20) 전압이며,

는 ESS(40) 또는 EVC(50) 설치 위치까지의 계통(20) 전류를 나타낸다.Here, Zn is the line impedance of the low voltage system 20 from the pole transformer 21 of the system 20 to the ESS 40 installation position, and lR represents a linear regression method. Also,

is the secondary voltage of the pole transformer 21 of the grid 20,

is the grid (20) voltage at the installation location of the ESS (40) or EVC (50) before the operation of the ESS (40),

represents the grid 20 current up to the ESS (40) or EVC (50) installation location.

는 ESS(40) 또는 EVC(50) 설치 위치에서의 계통(20) 역률이고, m은 측정시간대이며, n은 저압 계통(20)의 ESS(40) 설치 구간을 나타낸다. 이때, 저압선로에서의 ESS(40)에 의한 전력안정화는 유효전력에 의해서 보상되므로 상기 선로임피던스는 유효분에 대해서만 계산된다.Also,

is the power factor of the system 20 at the ESS 40 or EVC 50 installation location, m is the measurement time period, and n indicates the ESS 40 installation section of the low voltage system 20 . At this time, since power stabilization by the ESS 40 in the low voltage line is compensated by the active power, the line impedance is calculated only for the effective component.

In addition, the line impedance, which is a voltage adjustment element by the ESS 40, is operated as a fixed value once it is determined. Therefore, in order to adjust the voltage by the ESS 40, it is necessary to calculate the value to minimize the deviation of the ideal impedance value according to the current change rather than the impedance value during installation. It can be formulated as [Equation 2] below.

[Equation 2]

이며, T는 전체시간대(Total number of time interval)를 나타낸다. 또한, 임피던스는 도 3과 같이 전체시간대(T)에 대하여 계통(20) 전압과 부하전류로 도출된 직선들의 선형회귀 분석을 통해 최적 기울기 값을 구하고, 이를 통해 최적 임피던스를 결정할 수 있다.where q is the error function,

, and T represents a total number of time intervals. In addition, as shown in FIG. 3 , the optimum slope value is obtained through linear regression analysis of straight lines derived from the system voltage and the load current for the entire time period T for the impedance, and the optimum impedance can be determined through this.

When the optimum impedance (Z _n ) of the entire period of consideration (T) is obtained using [Equation 2], [Equation 3] is shown below.

[Equation 3]

Here, the voltage drop (V _drop (t)) to the installation position of the ESS 40 means the voltage difference between the voltage of the pole transformer side 21 and the installation section of the ESS 40 .

4 is a diagram showing the voltage state of the system 20 according to the control of the ESS 40 of the present invention, and FIGS. 5A and 5B are diagrams showing the load current of the system 20 according to the control of the ESS 40 of the present invention It is a drawing. That is, FIG. 5A is a view showing the load current characteristics of the system 20 when the ESS 40 is charged, and FIG. 5B is a view showing the load current characteristics of the system 20 when the ESS 40 is discharged.

The calculating unit 120 calculates a compensation voltage of the ESS 40 for stabilizing the voltage of the system 20 using the voltage of the system 20 measured by the voltage and current measurement unit 110 based on the calculated line impedance. can

As shown in FIG. 4 , when the voltage of the grid 20 rises due to an increase in the amount of power generation of the renewable energy power source 30 , the system 40 by controlling the ESS 40 in a charged state equals the compensation voltage of the ESS 40 . ) can reduce the voltage.

Therefore, as shown in the section (A) of FIG. 4 , the system 20 voltage (Without ESS) of the solid line that is out of the upper limit is the system 20 voltage (by ESS) that appears as a dotted line through the charging of the ESS 40 . charging) to keep it within the standard range (within the upper limit voltage value).

In addition, when the voltage of the system 20 drops due to an increase in the amount of charge and load of the EVC (Electric Vehicle Charging) 50, the compensation voltage of the ESS 40 is controlled by controlling the ESS 40 to a discharged state. It is possible to increase the voltage of the system 40 as much as possible.

Therefore, as shown in the section (B) of FIG. 4 , the system 20 voltage (Without ESS) of the solid line that is out of the lower limit is the system 20 voltage (by ESS) that appears as a dotted line through the discharge of the ESS 40 . charging) to keep it within the standard range (within the lower limit voltage value).

6 is a diagram showing in detail the voltage of the system 20 according to charging and discharging of the ESS 40, and FIG. 7 is a diagram showing charging the ESS 40 by applying a voltage compensation range margin, FIG. 8 is a view showing the charging and discharging operation state of the ESS 40 according to the voltage state of the system 20 .

That is, FIG. 7 is a diagram illustrating charging of the ESS 40 by applying the voltage compensation range margin when the voltage of the system 20 deviates from the upper limit voltage boundary.

The determination unit 130 monitors the voltage of the grid 20 measured by the voltage and current measurement unit 110 in real time to determine whether the voltage of the grid 20 is within a voltage reference range between the upper limit voltage and the lower limit voltage. In addition, when the voltage of the system 20 is out of the voltage reference range (upper-limit voltage or lower-limit voltage) according to the determination result of the determination unit 130, the charge/discharge control unit 140 controls the ESS ( 40) to compensate the voltage of the system 20. That is, the system 20 is stabilized by controlling the ESS 40 as much as the voltage compensation range for compensating the voltage of the system 20 .

In this case, when the voltage compensation range is limited only to the upper and lower voltage boundaries of the system 20 , the operation of the ESS 40 by the charge/discharge controller 140 may occur frequently. The frequent operation of the ESS 40 may cause a problem in that the voltage of the system 20 cannot be maintained within a prescribed range due to a measurement error or the like.

Therefore, the wind power generation and solar power generation-related electric charging system 10 according to an embodiment of the present invention uses a voltage compensation range margin (VCR, Voltage Compensation Rate) to which a margin is applied to the voltage compensation range as shown in FIG. 7 . to control charging or discharging of the ESS 40 . That is, the charge/discharge control unit 140 applies the margin to the upper and lower limit voltages of the grid 20 voltage, and controls the ESS 40 up to the voltage value to which the margin is applied.

Through this, frequent operation of the ESS 40 is prevented by overcompensating the voltage of the system 20 , and the voltage of the system 20 can be maintained as stable as possible.

9 is a diagram illustrating a State of Charge (SOC) for operation of the ESS 40 .

In general, when the ESS 40 is applied to the system 20 and operated, the charging or discharging operation of the ESS 40 is continuously performed based on a 50% state of charge (SOC). However, there is a problem in applying the 50% SOC because the number of times of charging and discharging according to time is different in the wind power generation and solar power generation linked electric charging system 10 according to an embodiment of the present invention.

Therefore, the wind power generation and solar power generation-related electric charging system 10 according to an embodiment of the present invention considers the charging or discharging of the ESS 40 through the operation unit 120 as shown in FIG. ) of the operating point (SOR, State of Reference) is calculated.

That is, when the initial ESS 40 is installed, the SOC is applied as a standard of 50%, and then the appropriate operating point of the ESS 40 is calculated according to the charging or discharging operation characteristics of the ESS 40 and the operating point (SOR, State). of Reference).

The operating point (SOR) may be calculated as the sum of the SOC 50% and the rate of change [%] of the charge/discharge capacity of the ESS 40 for each time period as shown in FIG. 9 . Here, since the appropriate SOC of the ESS 40 is determined by the operation of the ESS 40 for each time period, the appropriate SOC value of the ESS 40 for each time period is different.

Therefore, the appropriate operating point (SOR) of the SOC is the charging operating capacity (kW) and the discharging operating capacity of the ESS 40 in the target time zone according to the charging/discharging operation data of the ESS 40 as shown in [Equation 4] below. It is calculated by dividing the difference in (kW) by the sum of the charging operating capacity and the discharging operating capacity (kW), and applying SOC 50% to this value.

[Equation 4]

는 ESS(40)의 시간대별 SOC 기준 운용점이고, P_ESS-Charge(t)는 ESS(40)의 충전용량(kW)이며, P_ESS-dicharge(t)는 ESS(40)의 방전용량(kW)이다. 또한, th는 SOR 적용 시간대(hour)를 나타낸다.From here,

is the SOC standard operating point for each time period of the ESS (40), P _ESS-Charge (t) is the charging capacity (kW) of the ESS (40), and P _ESS-dicharge (t) is the discharging capacity (kW) of the ESS (40) )to be. In addition, th represents an SOR application time period (hour).

In this case, the operation of the ESS 40 for each time period may be calculated through a predetermined operation time. For example, when the operating time is set to 24 hours as shown in FIG. 9 , the appropriate SOC range for each time zone is changed every 24 hours using data from the previous day.

On the other hand, when the ESS 40 is operated to maintain the appropriate operating range, if the set width of the appropriate operating range is small, the ESS 40 performs frequent operations. Therefore, in order to compensate for these shortcomings, the wind power generation and solar power generation linked electric charging system 10 according to an embodiment of the present invention sets a margin of ±DB% in the appropriate SOC range for each time period.

In addition, the margin ratio of the appropriate SOC reference operating point (SOR) may be expressed as in [Equation 5] below.

[Equation 5]

Here, DB represents the margin of the appropriate SOC reference operating point (SOR).

10A and 10B are diagrams illustrating the operation of the ESS 40 according to the voltage state for each section of the system 20 . That is, FIG. 10A is a diagram illustrating a case in which the voltage exceeds the upper and lower limit boundary ranges (upper-limit voltage or lower-limit voltage) only in one section of the system 20 , and FIG. It is a diagram showing a case where the range (upper-limit voltage or lower-limit voltage) is out of range.

When the voltage on the low voltage system 20 exceeds the upper limit voltage or the lower limit voltage and when the appropriate SOC operation is constantly performed through the ESS 40 , the ESS 40 operation is the system 20 voltage measured for each section. is aimed at

For example, as shown in FIG. 10A , when the upper and lower voltages are out of the upper and lower limits in any one section of the voltage of the grid 20 , the ESS 40 determines the capacity by the compensated voltage level and then performs a charging or discharging operation.

In addition, as shown in FIG. 10b , when the upper and lower limit voltages are exceeded in a plurality of sections of the voltage of the grid 20 , the ESS 40 determines the operating capacity as much as the compensated voltage based on the voltage of the section most deviating from the upper and lower limit voltages, and then charges or discharge operation.

11 is a diagram illustrating a case in which the SOC of the ESS 40 is out of an appropriate maintenance range (SOR). As shown in FIG. 11 , while the voltage of all sections of the system 20 is maintained within the reference voltage range in a state in which the ESS 40 for voltage stabilization does not perform a charging/discharging operation, the SOC of the ESS 40 is maintained within an appropriate maintenance range. When out of (SOR), the ESS 40 performs SOC operation up to an appropriate operating range under the control of the charge/discharge control unit 140 .

In addition, the storage unit 150 stores the voltage value and current value of the system 20 measured by the voltage and current measurement unit 110 and the line impedance calculated through the operation unit 120 and the compensation voltage value of the ESS 40 . Save.

As described above, the wind power generation and solar power generation linked electric charging system 10 according to the embodiment of the present invention can stabilize the power of the low voltage distribution system 20 through the control of the ESS 40 .

12 is a flowchart illustrating a wind power generation and photovoltaic power generation-linked electric charging method according to an embodiment of the present invention, and FIG. 13 is a view showing an operation procedure of the ESS 40 according to an embodiment of the present invention.

In the wind power generation and photovoltaic power generation-linked electric charging method according to an embodiment of the present invention, the voltage and current measurement unit 110 is an EVC (electric vehicle charging) 50 charging amount and load amount and renewable energy power source ( A step (S10) of measuring the voltage and current of the system 20, which is changed according to the amount of power generated in 30) in real time (S10), and the low voltage system 20 based on the voltage and current values of the system 20 measured by the calculating unit 120 ) of extracting the maximum allowable current in each section and the line impedance up to the corresponding section (S20).

In addition, the operation unit 120 extracts the voltage fluctuation range of the ESS 40 based on the average holding voltage and the capacity of the system 20 stably maintaining the ESS 40 or EVC 50 installation stage (S30) ), and the operation unit 120 extracting the upper limit voltage and the lower limit voltage that are the maintenance ranges of the grid 20 voltage by using the voltage fluctuation range (S40).

At this time, in the step (S30) of extracting the voltage fluctuation width of the ESS 40, the voltage fluctuation width, which is an important factor for determining the upper limit voltage and the lower limit voltage, which are the maintenance ranges of the grid 20 voltage, is [Equation 6] and It is calculated as a value obtained by dividing the product of the maximum allowable current of each section and the line impedance in the low voltage system 20 as well as the margin ratio.

[Equation 6]

Here, I _max is the maximum allowable current of the system 20 , ±U _violation is the upper and lower limit fluctuation width of the ESS 40 , and MR represents the margin ratio. In this case, the margin ratio may be a value (eg, 1.2) determined on the basis of the load factor 0.8 during heavy load of the system 20 . In addition, the variation width of each section with respect to the margin ratio has the same value because of the linear characteristic of the voltage according to the magnitude of the current.

In addition, the step of extracting the upper limit voltage and the lower limit voltage (S40) is an average holding voltage (U _n ) at which the ESS (40) or EVC (50) installation stage is stably maintained as shown in [Equation 7] below; The upper limit voltage and lower limit voltage, which are the maintenance ranges of the grid 20 voltage, are extracted using the voltage fluctuation range (±U _violation ) considering the capacity of the grid 20 .

[Equation 7]

Here, U _Uoper is the operating upper limit voltage of the ESS 40 , U _Loper is the operating lower limit voltage of the ESS 40 , and U _n is the reference voltage (eg, 220V) of the ESS 40 installation stage.

In addition, in the wind power generation and photovoltaic power generation-linked electric charging method according to an embodiment of the present invention, the determination unit 130 monitors the voltage of the system 20 measured by the voltage and current measurement unit 110 in real time, and the system ( Step (S50) of determining whether the voltage of 20) is within a voltage reference range between the upper limit voltage and the lower limit voltage, and when the voltage of the grid 20 is not within the voltage reference range, the line calculated by the calculator 120 It may include calculating a compensation voltage of the ESS 40 for stabilizing the voltage of the system 20 using the voltage of the system 20 measured by the impedance and voltage and current measuring unit 110 ( S60 ). .

In this case, frequent operation of the ESS 40 may occur according to frequent voltage fluctuations of the low voltage system 20 . Typically, there is a lamp late time when the PCS of the ESS 40 operates at a target power value.

In addition, in general, the F/R generator with the power adjustment function is operated with an average power value for 10 seconds. For this reason, when considering the lamp time of the PCS for the ESS 40 and the lifetime of the device, it becomes a problem for the ESS 40 to operate as an instantaneous value.

Therefore, the step of calculating the compensation voltage of the ESS 40 (S60) is to set the real-time section voltage of the system 20 for a predetermined time in order to secure the stability of the ESS 40 through securing the operation time of the ESS 40. The method may further include calculating a compensation voltage by applying it as an average value of ( S61 ).

In this case, the operating time of the ESS 40 is determined so that the capacity of the ESS 40 is fixedly operated during the time during which the average value of the system 20 is calculated. In addition, the average value of the section voltage of the grid 20 may be calculated as in [Equation 8] below.

[Equation 8]

는 t_x 초 동안 계통(20) 구간전압의 평균값이고, t_x는 ESS(40)의 동작지속시간이며,

는 실시간 계통(20) 구간전압을 나타낸다.From here,

is the average value of the system 20 section voltage for t _x seconds, t _x is the operation duration of the ESS 40,

represents the real-time system 20 section voltage.

In addition, calculating the compensation voltage of the ESS 40 ( S60 ) is performed using a voltage compensation range margin (VCR, Voltage Compensation Rate) in which a margin is applied to the voltage reference range (upper-limit voltage or lower-limit voltage). The method may further include calculating the compensation voltage ( S62 ).

In addition, according to the determination result of the determination unit 130 in the wind power generation and photovoltaic power generation-linked electric charging method according to an embodiment of the present invention, when the voltage of the grid 20 is not within the voltage reference range, the charge/discharge control unit ( 140 ) may include a step ( S70 ) of controlling the ESS 40 to compensate the compensation voltage calculated by the operation unit 120 to the system 20 .

At this time, the step (S70) of compensating the compensation voltage to the grid 20 is characterized in that it is determined whether the ESS 40 is operated according to the voltage level for each section of the grid 20.

For example, if even one section of the voltage of the low voltage system 20 is out of the preset reference voltage range (upper-limit voltage range (U _Uoper ), lower-limit voltage range (U _Loper )), the ESS (40) ) to determine whether it works.

That is, when the section voltage of the grid 20 is out of the upper limit operation range, the ESS 40 performs a charging operation under the control of the charge/discharge control unit 140, and if the section voltage of the grid 20 is less than the lower limit operation range The charging/discharging control unit 140 controls the ESS 40 to perform a discharging operation.

[Equation 9] below shows a formula for determining whether to charge or discharge the ESS 40 according to the voltage magnitude comparison.

[Equation 9]

는 ESS(40)의 전압 안정화를 위한 방전동작 신호를 나타내고,

는 ESS(40)의 전압 안정화를 위한 충전동작 신호를 나타낸다. 또한,

는 ESS(40)의 운용 전 ESS(40) 또는 EVC(50) 설치 위치의 계통(20) 전압이고, △U_ESS는 ESS(40)에 의한 전압 보상범위를 나타낸다. 또한, U_Uoper는 ESS(40)의 운용 상한 전압이고, U_Loper는 ESS(40)의 운용 하한 전압이다.From here,

represents a discharge operation signal for voltage stabilization of the ESS (40),

denotes a charging operation signal for voltage stabilization of the ESS 40 . Also,

is the grid 20 voltage at the installation location of the ESS 40 or EVC 50 before operation of the ESS 40, and ΔU _ESS represents the voltage compensation range by the ESS 40. In addition, U _Uoper is an operating upper limit voltage of the ESS 40 , and U _Loper is an operating lower limit voltage of the ESS 40 .

)가 고려된다. 이때, ESS(40)의 최초 동작시 이전시간대의 전압 보상범위는 0으로 가정할 수 있다.In [Equation 9], the voltage compensation range (

) is considered. In this case, it may be assumed that the voltage compensation range of the previous time period is 0 during the initial operation of the ESS 40 .

In addition, when the ESS 40 does not operate for stabilizing the voltage of the grid 20 , charging or discharging of the ESS 40 may be performed by determining a State of Reference (SOR).

In [Equation 9], when all section voltages of the system 20 satisfy the reference voltage range, the charge/discharge signal of the ESS 40 should be determined as α=0, β=0. In addition, it is determined whether all section voltages of the system 20 are maintained within a margin based on the reference voltage within the range of the reference voltage and the upper limit operating voltage of the ESS 40 .

For example, an equation for determining whether to maintain the margin within 50% by setting the margin to 50% is [Equation 10] below.

[Equation 10]

는 SOR 연산을 위한 초기 상태 신호를 나타낸다.From here,

denotes an initial state signal for SOR operation.

At this time, when the SOC operation is performed, the voltage of the system 20 has a characteristic that does not deviate from the upper and lower limit operating ranges, but in order to reduce voltage variability, the set voltage for the SOC operation is calculated to be within 50% of the reference voltage.

In addition, if the current SOC state of the ESS 40 is out of the SOR range while all of the above conditions are satisfied, the SOC charging/discharging operation is determined. That is, if the current SOC of the ESS 40 is less than the SOR range, the charge/discharge control unit 140 applies a charging operation signal to the ESS 40 , and if it is above the SOR range, the charge/discharge control unit 140 discharges to the ESS 40 . Apply the operation signal.

Such a charging or discharging operation signal may be expressed as in [Equation 11] below.

[Equation 11]

는 SOR의 동작을 위한 충전 신호를 나타내고,

는 SOR의 동작을 위한 방전 신호를 나타낸다.From here,

represents the charging signal for the operation of the SOR,

denotes a discharge signal for SOR operation.

Accordingly, if the conditions are classified for the charge/discharge signal of the ESS 40 operated for stabilizing the voltage of the grid 20 and the charge/discharge signal operated as the SOC, it can be expressed as follows.

[Table 1] Classification of operation signals of ESS (40)

In addition, when the charging/discharging operation of the ESS 40 for safety of the grid 20 voltage is determined, the operation unit 120 operates the upper limit voltage U _Uoper of the ESS 40 as shown in [Equation 12] below. and the operating lower limit voltage (U _Loper ) of the ESS (40), the voltage compensation range margin, the voltage compensation range (ΔU _ESS (t-1)) of the previous time period, and the charge/discharge operation signal of the ESS (40) Determine the voltage compensation range.

[Equation 12]

At this time,

는 전압 보상범위 여유도를 나타낸다.Here, ΔU _ESS is the voltage compensation range by the ESS 40,

represents the margin of voltage compensation range.

At this time, it is assumed that the voltage compensation range of the previous time period is 0 when the ESS 40 is not operated during the initial operation of the ESS 40 and during the previous time period. In addition, it is preferable to set the margin to a value between 0.95 and 0.85 in consideration of the error caused by the operation of the ESS 40 .

In addition, when ΔU _ESS is a - value, it means a voltage compensation range by discharging the ESS 40 , and when it is a + value, it indicates a voltage compensation range by charging the ESS 40 .

에 의하여 ESS(40)의 SOC 운용이 결정된다.In addition, when the ESS 40 does not perform the voltage stabilization operation, as shown in Equation 13 below, α = 0, β = 0, which are the ESS 40 charge/discharge signals of Equation 9, and the ESS (40) SOC operation signal and charge/discharge operation signal of [Equation 10] and [Equation 11]

SOC operation of the ESS 40 is determined by

[Equation 13]

는 ESS(40)의 충방전 전력을 나타낸다.From here,

represents the charge/discharge power of the ESS 40 .

)은 자기 용량의 1/4 이내로 산정하는 것이 바람직하다.At this time, as in [Equation 13], the charge/discharge capacity of the ESS 40 (

) is preferably calculated within 1/4 of the self-capacitance.

In addition, the ESS 40 may determine the operating capacity of the ESS 40 according to the characteristics of charging and discharging at 0.2 C during the efficiency test, and recrystallize the operating capacity according to the installation environment and conditions of the ESS 40 . .

)은 아래의 [수학식 14]와 같이 상기 [수학식 12]의 전압 보상범위(△U_ESS)와 상기 선로임피던스의 크기에 의하여 결정될 수 있다.In addition, the charging/discharging power (

) may be determined by the voltage compensation range (ΔU _ESS ) of the [Equation 12] and the size of the line impedance as shown in [Equation 14] below.

[Equation 14]

Here, when the SOC of the ESS 40 is operated, a charging/discharging operation may be performed with the capacity of the ESS 40 as shown in [Equation 13]. In addition, thereafter, after a preset repetition time (t=t+1), the operation of the ESS 40 may be determined again by repeatedly performing from the step S40 of extracting the upper limit voltage and the lower limit voltage.

As such, the wind power generation and solar power generation-related electric charging system 10 and method according to the embodiment of the present invention are the charging amount and load of the EVC (Electric Vehicle Charging) 50 and the renewable energy power source (RES). , Renewable Energy Resource) (30) can be stabilized by controlling the voltage of the ESS (Energy Storage System) (40) the power of the system 20, which varies according to the amount of power generation.

That is, when the amount of charge and the load of the EVC (Electric Vehicle Charging) 50 in the low voltage system 20 are large, the limit capacity of the system 20 is maintained through the discharging of the ESS 40, and renewable When the amount of power generated by the energy power source 30 is large, the power of the grid 20 is stabilized by charging the ESS 40 to maintain the voltage of the grid 20 within the reference range.

Although the preferred embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and it is easily changed by a person skilled in the art from the embodiment of the present invention to equivalent Including all changes to the extent recognized as being

10: electric charging system 20: system
21: pole transformer 30: renewable energy power source
31: wind power generation 32: solar power generation
40: ESS (Energy Storage System)
50: EVC (Electric Vehicle Charging)
51: EV (Electric Vehicle)
60: load 110: voltage and current measuring unit
120: calculation unit 130: judgment unit
140: charge/discharge control unit 150: storage unit

Claims (20)

delete A voltage and current measuring unit that measures the voltage and current values of the system that change according to the amount of charge and load of EVC (Electric Vehicle Charging) and the amount of power generation of renewable energy sources;
The line impedance of the system is calculated using the measured voltage and current values of the system, and the voltage of the system is stabilized using the voltage value of the system measured in real time by the voltage and current measuring unit based on the calculated line impedance. Calculate the compensation voltage of the ESS (Energy Storage System) for an operation unit that calculates (SOR, State of Reference);
a determination unit that monitors the voltage value of the system measured by the voltage and current measurement unit in real time to determine whether the voltage value of the system is within a voltage reference range; and
When the voltage of the grid is not within the voltage reference range according to the determination result of the determination unit, a charge/discharge control unit that controls the ESS to provide a compensation voltage to the grid in order to stabilize the voltage of the grid;
Wind power and photovoltaic power generation linked electric charging system, characterized in that it comprises.
3. The method of claim 2,
The charging/discharging control unit controls the ESS to perform a charging operation when at least one section of the system exceeds a preset upper limit voltage value, and controls the ESS to perform a discharge operation when at least one section of the system is less than a preset lower limit value Wind power generation and solar power generation linked electric charging system, characterized in that to perform.
◈Claim 4 was abandoned when paying the registration fee.◈ A voltage and current measuring unit that measures the voltage and current values of the system that change according to the amount of charge and load of EVC (Electric Vehicle Charging) and the amount of power generation of renewable energy sources;
The line impedance of the system is calculated using the measured voltage and current values of the system, and the voltage of the system is stabilized using the voltage value of the system measured in real time by the voltage and current measuring unit based on the calculated line impedance. an arithmetic unit for calculating a compensation voltage of an Energy Storage System (ESS);
a determination unit that monitors the voltage value of the system measured by the voltage and current measurement unit in real time to determine whether the voltage of the system is within a voltage reference range; and
When the voltage value of the system is not within the voltage reference range according to the determination result of the determination unit, a charge/discharge control unit that controls the ESS to stabilize the voltage of the system to provide a compensation voltage to the system;
The charging/discharging control unit controls the ESS to perform a charging operation when at least one section of the system exceeds a preset upper limit voltage value, and controls the ESS to perform a discharging operation when at least one section of the system is less than a preset lower limit value perform,
The charging/discharging control unit uses the following [Equation 1] to determine whether the charging or discharging operation of the ESS according to the comparison of voltage values.
[Equation 1]

From here,

represents the discharge operation signal for voltage stabilization of the ESS,

represents the charging operation signal for voltage stabilization of the ESS. Also,

is the grid voltage of the ESS or EVC installation location before operation of the ESS, and △U _ESS is the voltage compensation range by the ESS. In addition, U _Uoper is the operating upper limit voltage of the ESS, and U _Loper is the operating lower limit voltage of the ESS.
◈Claim 5 was abandoned when paying the registration fee.◈ A voltage and current measuring unit that measures the voltage and current values of the system that change according to the amount of charge and load of EVC (Electric Vehicle Charging) and the amount of power generation of renewable energy sources;
The line impedance of the system is calculated using the measured voltage and current values of the system, and the voltage of the system is stabilized using the voltage value of the system measured in real time by the voltage and current measuring unit based on the calculated line impedance. an arithmetic unit for calculating a compensation voltage of an Energy Storage System (ESS);
a determination unit that monitors the voltage value of the system measured by the voltage and current measurement unit in real time to determine whether the voltage of the system is within a voltage reference range; and
When the voltage of the grid is not within the voltage reference range according to the determination result of the determination unit, a charge/discharge control unit that controls the ESS to stabilize the voltage of the grid to provide a compensation voltage to the grid;
The charging/discharging control unit controls the ESS to perform a charging operation when at least one section of the system exceeds a preset upper limit voltage value, and controls the ESS to perform a discharge operation when at least one section of the system is less than a preset lower limit value perform,
The charge/discharge control unit uses the following [Equation 2] to determine whether the charging or discharging operation of the ESS according to the SOC state is a wind power generation and solar power generation linked electric charging system, characterized in that.
[Equation 2]

From here,

represents a charging signal for the operation of the SOR (State of Reference),

denotes a discharge signal for SOR operation. In addition, SOC (State of Charge) indicates the state of charge or charging rate of the battery, SOR (State of Reference) indicates an operating point for charging or discharging the battery, and DB indicates an appropriate SOC reference operating point (SOR) margin ratio. indicates
3. The method of claim 2,
The calculation unit performs a linear regression analysis ( Linear Regression method) using a wind power generation and solar power generation linked electric charging system, characterized in that for calculating the line impedance.
3. The method of claim 2,
The calculation unit uses the following [Equation 3] to calculate the impedance for a total number of time intervals.
[Equation 3]

Here, Z _n represents the impedance of the entire study period (T).
3. The method of claim 2,
When the voltage value of the system is not within the voltage reference range, the calculation unit is a voltage compensation range margin (VCR, Voltage Compensation Rate) in which a margin is applied to the charging voltage or discharging voltage of the ESS calculated to stabilize the voltage of the system. Wind power and photovoltaic power generation-linked electric charging system, characterized in that it calculates the compensation voltage of the ESS using
3. The method of claim 2,
The calculation unit extracts the maximum allowable current of the system from the pole transformer of the system to the terminal section where the ESS is installed using the voltage characteristic at the time of heavy load and the voltage characteristic according to the maximum amount of power generation of the renewable energy power source Wind power, characterized in that Electric charging system linked to power generation and photovoltaic power generation.
delete 3. The method of claim 2,
The appropriate operating point (SOR, State of Reference) of the SOC divides the difference between the charging and discharging operating capacity of the ESS by the sum of the charging operating capacity and the discharging operating capacity in the target time period in which charging or discharging of the ESS is performed, Wind power and photovoltaic power generation linked electric charging system, characterized in that it is calculated by applying 50% of SOC to the divided value.
delete Measuring the voltage value and current value of the system that varies according to the amount of charge and load of EVC (Electric Vehicle Charging) and the amount of power generation of a renewable energy source;
ESS (Energy) for calculating the line impedance of the grid using the measured voltage and current values of the grid, and stabilizing the voltage of the grid using the voltage value of the grid measured in real time based on the calculated line impedance The compensation voltage of the storage system is calculated, and the appropriate operating point (SOR, State of Reference);
determining whether the voltage value of the system is within a voltage reference range by monitoring the measured voltage value of the system in real time; and
When the voltage value of the grid is not within the voltage reference range according to the determination result, controlling the ESS to provide a compensation voltage to the grid in order to stabilize the voltage of the grid;
Wind power and photovoltaic power generation-linked electric charging method, characterized in that it comprises.
◈Claim 14 was abandoned at the time of payment of the registration fee.◈ 14. The method of claim 13,
The step of calculating the line impedance includes the voltage value measured at the pole transformer of the system, the voltage value and current value of the system measured at the ESS or EVC installation location before operation of the ESS, and the grid power factor at the ESS or EVC installation location. Wind power and photovoltaic power generation-linked electricity charging method, characterized in that the line impedance is calculated using a linear regression method.
◈Claim 15 was abandoned when paying the registration fee.◈ 14. The method of claim 13,
Wind power comprising the step of calculating a compensation voltage of the ESS for stabilizing the voltage of the grid if the voltage value of the grid is not within the voltage reference range after determining whether it is within the voltage reference range Electricity charging method linked to power generation and photovoltaic power generation.
◈Claim 16 has been abandoned at the time of payment of the registration fee.◈ 16. The method of claim 15,
Controlling the ESS and compensating for the calculated compensation voltage to the system.
◈Claim 17 was abandoned when paying the registration fee.◈ 17. The method of claim 16,
Wind power generation, characterized in that when the voltage of at least one section of the system exceeds a preset upper limit value, the ESS performs a charging operation, and when at least one section is less than a preset lower limit value, the ESS performs a discharging operation and photovoltaic power generation-linked electric charging method.
◈Claim 18 was abandoned when paying the registration fee.◈ 16. The method of claim 15,
In the step of calculating the appropriate operating point (SOR, State of Reference) of the SOC, the difference between the charging operating capacity and the discharging operating capacity of the ESS in the target time period in which the charging or discharging of the ESS is performed is the difference between the charging operating capacity and the discharging operating capacity. Wind power generation and solar power generation-linked electricity charging method, characterized in that it is calculated by dividing by the sum and applying 50% of the SOC to the divided value.
◈Claim 19 was abandoned at the time of payment of the registration fee.◈ 17. The method of claim 16,
The step of calculating the compensation voltage of the ESS is wind power generation, characterized in that the compensation voltage is calculated by applying the real-time section voltage of the system as an average value for a certain time in order to secure the stability of the ESS through securing the operation time of the ESS. and photovoltaic power generation-linked electric charging method.
17. The method of claim 16,
Calculating the compensation voltage of the ESS is wind power and solar power generation, characterized in that the compensation voltage is calculated using a voltage compensation range margin (VCR, Voltage Compensation Rate) to which the margin is applied to the voltage reference range. Linked electric charging method.

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