KR20200049000A - Droop control method and controller for bi-directional distributed generator - Google Patents

Abstract

Disclosed are a droop control method for a bi-directional distributed power supply and a device thereof. The droop control method for a bi-directional distributed power supply comprises the steps of: receiving line resistance and structure, maximum load consumption power, and maximum power generation, respectively; and droop-controlling output power of a bi-directional distributed generator to be within a predetermined voltage regulation range by using the line resistance and structure, maximum load consumption power, and maximum generation power.

Description

Droop control method and controller for bi-directional distributed generator}

The present invention relates to a droop control method and controller for a bidirectional distributed power supply.

As the power generation capacity of distributed generators (DGs) increases worldwide, research on microgrids (hereinafter referred to as MGs) to effectively use the generated power is actively being conducted. MG is a power system in which load and DG are interconnected, and is a small-scale power grid with independence operated in the form of grid-connected or independent operation depending on the situation. In particular, dc MG has good power quality, high power conversion efficiency, and convenience of control because it has no reactive power and harmonic components compared to ac. Various control strategies have been proposed for the stable and efficient operation of dc MG. Existing control strategies can be classified into centralized control, distributed control using communication, and decentralized control.

  Non-centralized control has the advantage of not requiring a communication system because it performs control only with local information, and generally uses droop control. The droop control controls the output voltage according to the increase or decrease of the output current of the DG, so that autonomous power sharing is achieved. In droop control, droop gain is an important parameter affecting control performance and stability, and droop gain must be properly designed in order to perform proper power sharing between DGs. When constructing a dc MG line, the line resistance affects the droop gain value, so a droop gain considering this needs to be designed.

In the case of the existing variable resistance type droop control device and method, there is a problem that it cannot be applied to a microgrid in which the system is linked because it is targeted to a standalone microgrid that controls a DC microgrid using only an energy storage device.

In addition, when distributed control is performed through a bidirectional distributed power supply in a DC microgrid, the droop gain is affected by line resistance, which causes a problem that control is not performed as originally designed.

The present invention is to provide a droop control method and controller for a bidirectional distributed power supply.

In addition, the present invention is to provide a droop control method and controller for a bidirectional distributed power supply in which a bidirectional distributed power supply in a DC microgrid can smoothly control power flow and maintain bus voltage regulation performance.

In addition, the present invention improves the power sharing accuracy of the distributed power supply through the droop control method and controller for bidirectional distributed power supply considering the line resistance, and at the same time, the voltage in the maximum load power consumption situation and the maximum power generation situation that can occur in the DC microgrid The present invention is to provide a droop control method and controller for a bidirectional distributed power supply capable of maintaining regulation performance.

According to an aspect of the present invention, a system and apparatus for droop control for a bidirectional distributed power supply are provided.

According to an embodiment of the present invention, a first bi-directional distributed generator (BDG) and a second bi-directional distributed generator constituting a microgrid; And a droop control device for droop-controlling the output power of the first bidirectional distributed generator and the second bidirectional distributed generator to be within a prescribed voltage regulation range in consideration of line resistances of the first and second bidirectional distributed generators. Power control system comprising a can be provided.

The microgrid may be direct current.

The droop control device derives a power sharing factor improvement coefficient value of the second bidirectional distributed generator based on a voltage sensitivity matrix derived using a power equation that linearizes a Jacobian matrix, and derives the derived power sharing rate improvement coefficient value. By using it, the droop gain of the first or second bidirectional distributed generator can be changed.

Derivation of the power sharing rate improvement coefficient value may derive the power sharing rate improvement coefficient value in the maximum load power consumption state and the maximum power generation state of the first or second bidirectional distributed generator, respectively, based on the voltage sensitivity matrix.

The droop control device recalculates the voltage sensitivity matrix by reflecting the power sharing factor, and uses the recalculated voltage sensitivity matrix to calculate the voltage fluctuation value in each bus at maximum load and maximum power generation. Although each is derived, the droop gain may be adjusted such that the maximum voltage variation among the voltage variation values in the respective buses is equal to or less than the set voltage variation width.

According to another embodiment of the present invention, a droop control device for a bidirectional distributed generator constituting a microgrid, comprising: an input unit for receiving line resistance and structure, maximum load consumption power, and maximum power generation; And a droop controller that droop-controls the output power of the bidirectional distributed generator to be within a predetermined voltage regulation range using the line resistance and structure, maximum load consumption power, and maximum generation power.

The droop controller derives a power sharing factor improvement coefficient value of the bidirectional distributed generator based on a voltage sensitivity matrix derived using a power equation that linearizes the Jacobian matrix, and uses the derived power sharing rate improvement coefficient value to The droop gain of the bidirectional distributed generator can be changed.

The droop controller may derive the power sharing factor improvement coefficient values in the maximum load power consumption state and the maximum power generation state of the bidirectional distributed generator, respectively, based on the voltage sensitivity matrix.

The droop controller recalculates the voltage sensitivity matrix by reflecting the power sharing factor, and uses the recalculated voltage sensitivity matrix to calculate the voltage fluctuation values of each bus at maximum load and maximum power generation, respectively. To derive, the droop gain may be adjusted such that the maximum voltage variation among the voltage variation values in each bus is equal to or less than the set voltage variation width.

The microgrid may be direct current.

According to another aspect of the present invention, a method for droop control of a bidirectional distributed generator in consideration of a line resistance of a microgrid is provided.

According to an embodiment of the present invention, a method for controlling a droop of a bidirectional distributed generator constituting a DC microgrid, comprising: receiving line resistance and structure, maximum load consumption power, and maximum power generation, respectively; And droop-controlling the output power of the bidirectional distributed generator to be within a predetermined voltage regulation range using the line resistance and structure, maximum load consumption power, and maximum power generation power.

In the step of controlling the droop, the power sharing rate of the bidirectional distributed generator is based on a voltage sensitivity matrix derived using a power equation that linearizes a Jacobian matrix based on the line resistance and structure, maximum load consumption power, and maximum generation power. Deriving an enhancement factor value; And changing the droop gain of the bidirectional distributed generator by using the derived power sharing rate improvement coefficient value.

In the step of deriving the power sharing rate improvement coefficient value, the power sharing rate improvement coefficient value in the maximum load power consumption state and the maximum power generation state of the bidirectional distributed generator may be respectively derived based on the voltage sensitivity matrix.

In the step of controlling the droop, the voltage sensitivity matrix is recalculated by reflecting the power sharing factor improvement coefficient value, and the voltage fluctuation value of each bus in a maximum load and a maximum power generation situation is recalculated using the recalculated voltage sensitivity matrix. Deriving each; And adjusting the droop gain so that the maximum voltage variation among the voltage variation values in each bus is equal to or less than the set voltage variation width.

The microgrid may be direct current.

By providing a droop control method and controller for a bidirectional distributed power supply according to an embodiment of the present invention, a bidirectional distributed power supply in a DC microgrid can smoothly control power flow and maintain bus voltage regulation performance.

In addition, the present invention improves the power sharing accuracy of the distributed power supply through the droop control method and controller for bidirectional distributed power supply considering the line resistance, and at the same time, the voltage in the maximum load power consumption situation and the maximum power generation situation that can occur in the DC microgrid Adjustment performance can be maintained.

)과 출력 전류(

)의 관계를 나타낸 도면.
도 4은 본 발명의 일 실시예에 따른 선로 저항을 고려한 드룹 제어 방법을 나타낸 순서도.
도 5는 본 발명의 일 실시예에 따른 드룹 제어 장치의 내부 구성을 설명하기 위해 도시한 도면.
도 6은 본 발명의 일 실시예에 따른 5-버스 그물망 선로를 구성한 실험 환경을 예시한 도면.
도 7은 도 6의 블록도.
도 8은 본 발명의 일 실시예에 따른 최대 부하 상황에 대한 실험 결과를 도시한 도면.
도 9은 본 발명의 일 실시예에 따른 최대 발전 상황에 대한 실험 결과를 도시한 도면.1 is a view showing a power control system according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating a tide analysis diagram reflecting a droop bus for droop control considering line resistance according to an embodiment of the present invention.
3 is an output voltage command for two BDGs having different rated capacities (

) And output current (

) Shows the relationship.
Figure 4 is a flow chart showing a droop control method considering the line resistance according to an embodiment of the present invention.
5 is a view for explaining the internal configuration of the droop control apparatus according to an embodiment of the present invention.
6 is a diagram illustrating an experimental environment configuring a 5-bus network line according to an embodiment of the present invention.
Fig. 7 is a block diagram of Fig. 6;
8 is a diagram showing an experimental result for a maximum load situation according to an embodiment of the present invention.
9 is a view showing an experiment result for the maximum power generation situation according to an embodiment of the present invention.

As used herein, a singular expression includes a plural expression unless the context clearly indicates otherwise. In this specification, the terms "consisting of" or "comprising" should not be construed as including all of the various components, or various steps described in the specification, among which some components or some steps It may not be included, or it should be construed to further include additional components or steps. In addition, terms such as “... unit” and “module” described in the specification mean a unit that processes at least one function or operation, which may be implemented in hardware or software, or a combination of hardware and software. .

The present invention can perform a voltage sensitivity analysis based on a tidal current analysis in which dispersion control characteristics are reflected in order to analyze the structural characteristics of a DC microgrid in which multiple lines and multiple distributed power sources are connected. The present invention relates to a droop control capable of improving a power sharing performance while satisfying a voltage regulation range in a maximum load and power generation situation based on a voltage sensitivity analysis in consideration of line resistance.

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

1 is a view showing a power control system according to an embodiment of the present invention.

Referring to FIG. 1, the power control system 100 according to an embodiment of the present invention includes a first two-way distributed generator 110, a second two-way distributed generator 120, an n-way two-way distributed generator 121, and a load ( 130) and the droop control device 140.

It is assumed that the first bidirectional distributed generator 110, the second bidirectional distributed generator 120, and the nth bidirectional distributed generator 121 are connected through respective buses.

The first two-way distributed generator 110 and the second two-way distributed generator 120 according to an embodiment of the present invention will be understood as the main constituents of the DC microgrid.

In an embodiment of the present invention, although the first bi-directional distributed generator 110, the second bi-directional distributed generator 120 and the DC microgrid are configured by the load, the second bi-directional distributed generator 120 is a plurality of days Can be.

That is, the bidirectional distributed generator having the largest rated capacity among the plurality of bidirectional distributed generators constituting the DC microgrid will be referred to as a first bidirectional distributed generator or a main bidirectional distributed generator. The rest of the two-way distributed generators will be collectively referred to as a second two-way distributed generator or a sub-two-way distributed generator.

That is, in the following description, the second quantity "? * Distributed generator" should be interpreted as an extended n "" * distributed generator.

The droop control device 140 is a device for droop control so that the output powers of the first and second bidirectional distributed generators are within a predetermined voltage regulation range in consideration of line resistance of a DC microgrid.

)과 출력 전류(

)의 관계를 나타낸 도면이다. 이해와 설명의 편의를 도모하기 위해 도 2를 참조하여 조류 해석 모델에 대해 간략하게 설명하기로 한다. FIG. 2 is a diagram illustrating a tide analysis diagram reflecting a droop bus for droop control considering line resistance according to an embodiment of the present invention, and FIG. 3 is an output voltage command for two BDGs having different rated capacities (

) And output current (

). For convenience of understanding and explanation, the current analysis model will be briefly described with reference to FIG. 2.

As shown in FIG. 2, a bidirectional distributed generator (BDG: Bi-directional DG, hereinafter referred to as BDG, hereinafter referred to as BDG) may be connected to an nth (n is a natural number) bus. 2, the BDG is shown as one, but the BDG constituting the DC microgrid may be plural as described in FIG.

BDG 210 may be connected by a line structure connected by two adjacent buses. At this time, droop control may be used to power the BDG.

)은 수학식 1에서 보여지는 바와 같이, 출력 전류(

)가 증가함에 따라 선형적으로 감소된다. Output voltage command by droop control method (

) As shown in equation 1, the output current (

) Increases linearly.

은 공칭전압(Nominal voltage)를 나타내고,

는 가상 저항(virtual resistance), 즉 드룹 게인을 나타낸다. here,

Indicates the nominal voltage,

Denotes virtual resistance, that is, droop gain.

를 결정할 수 있다. In general, when considering the power burden according to the rated capacity of the BDG, as shown in Equation (2)

Can decide.

는 허용 전압 변동 폭을 나타내고,

는 최소 허용 전압을 나타내며,

는 BDG의 정격용량을 나타낸다. here,

Denotes the allowable voltage fluctuation range,

Denotes the minimum allowable voltage,

Indicates the rated capacity of the BDG.

)과 출력 전류(

)의 관계를 나타낸다. 도 2에서

는 제1 BDG의 드룹 게인을 나타내고,

는 제2 BDG의 드룹 게인을 나타낸다. 또한,

는 제1 BDG의 정격 용량을 나타내고,

는 제2 BDG의 정격 용량을 나타낸다.

이

보다 큰 경우 수학식 2에 의해

이

보다 작으며, 제1 BDG는 더 많은 전력을 흡수 및 공급할 수 있다.3 is an output voltage command for two BDGs having different rated capacities (

) And output current (

). In Figure 2

Denotes the droop gain of the first BDG,

Denotes the droop gain of the second BDG. In addition,

Denotes the rated capacity of the first BDG,

Indicates the rated capacity of the second BDG.

this

If greater than by Equation 2

this

It is smaller, and the first BDG can absorb and supply more power.

In the case of an ideal DC microgrid without line resistance, accurate power distribution may be possible depending on the designed droop gain value. However, in the case of a general DC microgrid, a line resistance exists, and accordingly, power sharing and voltage regulation performance are deteriorated.

)을 나타낸 것이다. 여기서,

는 선로 저항의 등가 값을 나타낸다. Equation 3 is the effective value of the droop gain changed by the line resistance (

). here,

Indicates the equivalent value of the line resistance.

는 회로 해석을 통해 유도될 수 있으나, 여러 대가 환형(Ring)이나 그물망(mesh) 형태의 복잡한 선로 구성에 연계되는 경우 이를 유도하기 어려운 문제점이 있다. 이를 위해, 본 발명의 일 실시예에서는 선로 구성과 부하 및 신재생원의 연계 위치를 고려하여 허용 전압 범위를 유지함과 동시에 BDG간의 전력 분담이 이루어질 수 있도록 선로 저항을 고려한 드룹 제어 방법에 대해 도 3을 참조하여 설명하기로 한다. If it is a DC microgrid with a simple structure in which only two BDGs are connected,

Can be derived through circuit analysis, but it is difficult to induce this when multiple units are connected to a complex line configuration in the form of a ring or a mesh. To this end, according to an embodiment of the present invention, a droop control method in consideration of line resistance may be maintained while maintaining an allowable voltage range in consideration of a line configuration, a link location between a load and a renewable source, and power distribution between BDGs. It will be described with reference to.

4 is a flowchart illustrating a droop control method considering line resistance according to an embodiment of the present invention.

In step 410, the droop control device 140 calculates a voltage sensitivity matrix. Voltage sensitivity analysis is to determine the characteristics of the entire network by considering the line configuration, the droop gain of the bidirectional distributed power supply, the maximum capacity of the load and non-dispatchable distributed generator (NDG). It is an analytical method.

The voltage sensitivity matrix is calculated through a Jacobian matrix derived from the power equation of the bus in the DC microgrid.

는 수학식 2의 드룹 게인의 역수를 나타낸다. 이를 수학식으로 다시 정리하면 수학식 4와 같다.

Denotes the reciprocal of the droop gain in Equation 2. This can be summarized as Equation (4).

이라 칭하면, 이는 수학식 5와 같이 나타낼 수 있다. The sum of the current flowing through the BDG and the adjacent bus connected from the nth bus

If it is called, it can be expressed as Equation (5).

Equation 5 can be expressed by generalizing as in Equation 6.

)을 수학식 7과 같이 나타낼 수 있다. Here, h denotes a bus connected to the n-th bus, and N denotes the total number of buses of the dc microgrid. Power equation of n-th bus using equation (6)

) Can be expressed as Equation 7.

As already discussed above, the voltage sensitivity matrix can be derived by taking the Jacobian matrix inversely. The power equation linearized using the Jacobian matrix can be expressed as Equation (8).

는 전력 변동(에 대한 N대 1(N-by-1) 행렬을 나타내고,

는 버스전압 변동에 대한 N대 1행렬을 나타낸다. 자코비안 행렬 성분은 전력 방정식을 버스 전압에 대한 편미분으로써 얻을 수 있으며, 이에 대한 (n,m)번째 성분을 나타내면 수학식 9와 같이 나타낼 수 있다. here,

Denotes an N-by-1 matrix for power fluctuations (

Denotes an N-to-1 matrix for bus voltage fluctuations. The Jacobian matrix component can be obtained from the power equation as a partial derivative of the bus voltage, and the (n, m) -th component can be expressed as Equation (9).

)으로부터 제m 버스의 전압(V_m)을 편미분함으로써 획득될 수 있다. 이를 수학식 7에 적용하면 수학식 10과 같이 정리될 수 있다. That is, the (n, m) -th Jacobian matrix component is the power equation (

) Can be obtained by partial differentiation of the voltage V _m of the mth bus. If this is applied to equation (7), it can be summarized as equation (10).

은 수학식 11과 같이 간소하게 표현될 수 있다.

Can be expressed simply as in Equation 11.

As shown in Equation 11, the Jacobian matrix (J matrix) can be expressed only by line resistance and droop gain. The voltage-sensitivity matrix can be obtained by taking the J matrix inversely as in Equation (12).

에 대한 선형화된

를 수학식 13과 같이 나타낼 수 있다.Using Equation 12, Equation 8 may be summarized as Equation 13. That is, by equation (12)

For linearized

Can be expressed as Equation 13.

In an embodiment of the present invention, for the control of droop considering line resistance, a Jacobian matrix (J) is derived through line resistance and existing droop gain as in Equation 11, and the voltage sensitivity matrix (S) is calculated by taking the inverse matrix. Can be.

In step 415, the droop control device 140 derives a power burden rate improvement coefficient value using the voltage sensitivity matrix (S).

In one embodiment of the present invention, the BDG having the largest capacity among BDGs will be referred to as a main BDG, and other BDGs will be referred to as sub-BDGs.

라 칭하기로 한다. 이때, 메인 BDG의 전력 변동분 대비 타겟 서브 BDG의 전력 변동분의 비율로 정의된다. 결과적으로, 서브 BDG의 드룹 게인은 메인 BDG의 드룹 게인에 기초하여 조정될 수 있다.In one embodiment of the present invention, a specific BDG (x) power factor improvement coefficient value is

Let's call it. At this time, it is defined as the ratio of the power variation of the target sub BDG to the power variation of the main BDG. As a result, the droop gain of the sub BDG can be adjusted based on the droop gain of the main BDG.

)과 최대 발전 상황(

) 두가지로 표현될 수 있다. In addition, the power load factor improvement coefficient value is the maximum load situation (

) And the maximum development situation (

) It can be expressed in two ways.

If this is expressed by an equation, it is as shown in equation (14).

는 최대 부하의 정격 소비 전력을 나타내고,

는 NDG의 정격 발전 전력을 나타낸다.

는 단계 310에서 계산된 S 행렬의 (n,h)성분을 나타낸다.

가 1보다 큰 경우, 이는 메인 BDG 대비 x번째 서브 BDG에 더 큰 전압 변동이 발생하는 것을 의미하며, 이는 x번째 서브 BDG가 상대적으로 큰 출력을 담당함을 의미한다. Here, the load bus represents a bus connected to the load, and the NDG bus represents a bus connected to the NDG. In addition,

Denotes the rated power consumption of the maximum load,

Indicates the rated generation power of NDG.

Denotes the (n, h) component of the S matrix calculated in step 310.

When is greater than 1, this means that a larger voltage fluctuation occurs in the xth sub BDG compared to the main BDG, which means that the xth sub BDG is responsible for a relatively large output.

가 1보다 큰 경우, x번째 BDG의 드룹 게인에

를 곱하여 x번째 BDG의 드룹 게인을 증가시킨다. 이로 인해, x번째 BDG의 출력 전력이 상대적으로 감소됨으로써 전력 공유 성능이 향상될 수 있다. therefore,

Is greater than 1, the droop gain of the xth BDG

Multiply by to increase the droop gain of the xth BDG. Due to this, the output power of the x-th BDG may be relatively reduced, thereby improving power sharing performance.

)를 이용하여 드룹 게인을 다시 도출하고, 이를 반영하여 전압 민감도 행렬(S)를 다시 계산한다. In step 420, the droop control device 140 has a power burden rate improvement coefficient value (

) To derive the droop gain again, and reflect it to recalculate the voltage sensitivity matrix (S).

)를 이용하여 다시 도출된 드룹 게인은 수학식 15와 같이 나타낼 수 있다. For example, the derived power burden rate improvement coefficient value (

The droop gain derived again using) may be expressed as Equation (15).

값이 결정된다. because of this

The value is determined.

The voltage sensitivity matrix S may be calculated as a maximum load and a maximum power generation situation, respectively, by reflecting the newly derived droop gain.

The droop control device 140 may calculate the maximum power fluctuation value for the maximum load and the maximum power generation situation, respectively, using the voltage sensitivity matrix S recalculated for the maximum load and the maximum power generation situation. If this is expressed by the equation, it is the same as equation (16).

는 최대 부하 상황에서의 전압 민감도 행렬(S)을 나타내고,

는 최대 발전 상황에서의 전압 민감도 행렬(S)을 나타낸다. 또한,

와

는

와

을 성분으로 가지는 최대 전력 변동 행렬이고,

와

는 각각 최대 부하 및 최대 발전 상황에서의 전압 변동 행렬을 나타낸다. here,

Denotes the voltage sensitivity matrix (S) at maximum load,

Denotes the voltage sensitivity matrix (S) in the maximum power generation situation. In addition,

Wow

The

Wow

Is a maximum power variation matrix having as a component,

Wow

Denotes a matrix of voltage fluctuations under maximum load and maximum power generation, respectively.

는 행렬 성분 중 최대값을 찾는 함수이며, 이를 통해 변동이 가장 큰 버스의 전압값을 찾을 수 있다.

Is a function of finding the maximum value of the matrix components, and through this, the voltage value of the bus with the largest variation can be found.

In step 425, the droop control device 140 uses the voltage sensitivity matrix recalculated in the maximum load and the maximum power generation situation, and the voltage fluctuation value of the bus having the largest voltage fluctuation in the maximum load and maximum power generation situation (hereinafter, maximum voltage fluctuation) Value).

In step 430, the droop control device 140 determines the droop gain so that the maximum voltage variation in the maximum load and the maximum power generation condition is included within the reference voltage variation width.

가 기준 전압 변동 폭(

)보다 크면,

가

이내에 포함되도록

을 감소시킨 후 단계 320으로 진행한다. For example, the droop control device 140 may

Is the reference voltage fluctuation range (

)

end

To be included within

After the decrease, proceed to step 320.

가

보다 작아지도록 조건을 변경하면서 드룹 게인 도출 및 전압 민감도 행렬을 도출하는 과정을 다시 반복 수행할 수 있다. 이는

에 대해서도 동일하게 적용된다. That is, the droop control device 140

end

The process of deriving the droop gain and deriving the voltage sensitivity matrix can be repeated again while changing the conditions to be smaller. this is

The same applies to.

와

를 이용하여 최종 드룹 게인을 결정한다. In step 435, the droop control device 140 is

Wow

Use to determine the final droop gain.

5 is a view illustrating an internal configuration of a droop control apparatus according to an embodiment of the present invention.

5, the droop control apparatus 140 according to an embodiment of the present invention includes an input unit 510 and a droop controller 515.

The input unit 510 receives line resistance and structure, maximum load consumption power, and maximum power generation, respectively. That is, the input unit 510 may receive the structure and related information of the DC microgrid.

The droop controller 515 is a device for droop control so that the output power of the bidirectional distributed generator is within a predetermined voltage regulation range using line resistance and structure, maximum load consumption power, and maximum power generation power.

This droop controller 515 can be located in front of the internal controller of the bidirectional distributed generator, as shown in FIG. 6. Through this, the droop controller 515 may droop control at least one of the output power and the bus voltage of the bidirectional distributed generator according to the droop gain.

Detailed functions and operations of the droop controller 515 are the same as those described with reference to FIGS. 1 to 4, and thus duplicate description will be omitted.

6 is a diagram illustrating an experimental environment configuring a 5-bus network line according to an embodiment of the present invention, FIG. 7 is a block diagram of FIG. 6, and FIG. 8 is a maximum load situation according to an embodiment of the present invention It is a diagram showing the experimental results for, and Figure 9 is a diagram showing the experimental results for the maximum power generation situation according to an embodiment of the present invention.

Table 1 shows the detailed integer values of the distributed power, load, and line resistances. The new droop gain derived by considering the line resistance according to an embodiment of the present invention is shown in Table 2.

essence sign value Nominal voltage Vnom 120 V Bus voltage upper limit Vmax 126 V Bus voltage lower limit Vmin 114 V BDG 1 rated power Prated, 1 1500 W BDG 2 rated power Prated, 2 750 W BDG 3 rated power Prated, 3 750 W load 1 maximum power consumption Pload 1 1000 W load 2 resistance Rload 2 15 Ω load 3 resistance value Rload 3 15 Ω NDG 1 maximum power generation PNDG 1 1400 W NDG 2 maximum power generation PNDG 2 1000 W Line resistance between buses 1 and 2 R12 0.18 Ω Line resistance between buses 2 and 3 R23 0.22 Ω Line resistance between buses 2 and 5 R25 0.18 Ω Line resistance between buses 3 and 4 R34 0.18 Ω Line resistance between bus 4 and 5 R45 0.22 Ω Line resistance between buses 3 and 5 R35 0.3 Ω

# BDG Existing droop gain Load advantage situation Development advantage Rd αload βload R’d αgen βgen R’d One 0.456 1.000 0.65 0.296 1.000 0.71 0.324 2 0.912 1.422 0.65 0.843 1.322 0.71 0.856 3 0.912 1.421 0.65 0.842 1.315 0.71 0.851

Referring to FIG. 8, the left part of the waveform is the result when applying the existing droop gain, and the right part is the result when applying the droop gain calculated through the proposed design method. It can be seen that the power sharing accuracy is improved by applying the designed droop gain. Under maximum load, the voltage on buses 2, 3, 4, and 5 dropped below Vmin (114 V) to 113.3 V, 113.3 V, 113.1 V, and 113.7 V, respectively, when applying the existing droop gain. When applying the droop gain derived according to an embodiment of the above, it can be confirmed that the voltage of all the buses is Vmin or more. 9 shows an experimental waveform for the maximum power generation situation, and similarly, it can be confirmed that the power sharing accuracy is improved. In the maximum power generation situation, when applying the existing droop gain, the voltage of the bus 4 exceeded Vmax (126V) at 126.1V, but when applying the designed droop gain, it can be confirmed that the voltage of all buses is below Vmax. Through this, it can be seen that the voltage regulation ability is improved through the proposed method.

The apparatus and method according to an embodiment of the present invention may be implemented in a form of program instructions that can be executed through various computer means and may be recorded on a computer readable medium. Computer-readable media may include program instructions, data files, data structures, or the like alone or in combination. The program instructions recorded on the computer-readable medium may be specially designed and configured for the present invention or may be known and usable by those skilled in the computer software field. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks, and magnetic tapes, optical media such as CD-ROMs, DVDs, and magnetic media such as floptical disks. Includes hardware devices specifically configured to store and execute program instructions such as magneto-optical media and ROM, RAM, flash memory, and the like. Examples of program instructions include high-level language codes that can be executed by a computer using an interpreter, etc., as well as machine language codes produced by a compiler.

The hardware device described above may be configured to operate as one or more software modules to perform the operation of the present invention, and vice versa.

So far, the present invention has been focused on the embodiments. Those skilled in the art to which the present invention pertains will appreciate that the present invention may be implemented in a modified form without departing from the essential characteristics of the present invention. Therefore, the disclosed embodiments should be considered in terms of explanation, not limitation. The scope of the present invention is shown in the claims rather than the foregoing description, and all differences within the equivalent range should be interpreted as being included in the present invention.

100: power control system
110: first bidirectional distributed generator
120: second bidirectional distributed generator
130: load
140: droop control device

Claims (16)

A first bi-directional distributed generator (BDG) and a second bi-directional distributed generator constituting a microgrid; And
A droop control device for droop-controlling the output power of the first bi-directional distributed generator and the second bi-directional distributed generator within a predetermined voltage regulation range in consideration of the line resistance of the first bi-directional distributed generator and the second bi-directional distributed generator. Including power control system.
According to claim 1,
The microgrid is a power control system, characterized in that the direct current.
According to claim 1,
The droop control device,
Based on a voltage sensitivity matrix derived using a power equation obtained by linearizing a Jacobian matrix, a power sharing factor improvement coefficient value of the second bidirectional distributed generator is derived, and the first or Power control system, characterized by changing the droop gain of the second bidirectional distributed generator.
According to claim 3,
Derivation of the power sharing rate improvement coefficient value,
Power control system, characterized in that for deriving the maximum load power consumption state and the power generation factor improvement coefficient value in the maximum power generation state of the first or second bidirectional distributed generator, respectively, based on the voltage sensitivity matrix.
According to claim 3,
The droop control device,
Recalculating the voltage sensitivity matrix by reflecting the value of the power sharing factor, and using the recalculated voltage sensitivity matrix, derive the voltage fluctuation values of each bus at maximum load and maximum power generation, respectively,
Power control system, characterized in that to adjust the droop gain so that the maximum voltage fluctuation value of the voltage fluctuation value in each bus is less than the set voltage fluctuation width.
In the droop control device of the bidirectional distributed generator constituting the microgrid,
An input unit for receiving line resistance and structure, maximum load consumption power, and maximum generation power, respectively; And
A droop control device including a droop controller for drooping the output power of the bidirectional distributed generator within a predetermined voltage regulation range by using the line resistance and structure, maximum load consumption power, and maximum power generation.
The method of claim 6,
The droop controller,
Based on a voltage sensitivity matrix derived using a power equation obtained by linearizing a Jacobian matrix, a power sharing factor improvement coefficient value of the bidirectional distributed generator is derived, and a droop of the bidirectional distributed generator using the derived power sharing efficiency enhancement coefficient value. A droop control device characterized by changing the gain.
The method of claim 7,
The droop controller,
A droop control device for deriving the maximum load power consumption state and the power sharing factor improvement coefficient values in the maximum power generation state of the bidirectional distributed generator, respectively, based on the voltage sensitivity matrix.
The method of claim 7,
The droop controller,
Recalculating the voltage sensitivity matrix by reflecting the value of the power sharing factor, and using the recalculated voltage sensitivity matrix, derive the voltage fluctuation values of each bus at maximum load and maximum power generation, respectively,
A droop control device, wherein the droop gain is adjusted such that a maximum voltage variation among the voltage variation values in each bus is equal to or less than a set voltage variation width.
The method of claim 6,
The microgrid is a droop control device, characterized in that the direct current.
In the method for controlling the droop of a bidirectional distributed generator constituting a microgrid,
Receiving line resistance and structure, maximum load power consumption, and maximum power generation, respectively; And
And drooping the output power of the bidirectional distributed generator within a predetermined voltage regulation range by using the line resistance and structure, maximum load consumption power, and maximum generation power.
The method of claim 11,
The step of controlling the droop,
Deriving a power sharing factor improvement coefficient value of the bidirectional distributed generator based on a voltage sensitivity matrix derived using a power equation that linearizes a Jacobian matrix based on the line resistance and structure, maximum load consumption power, and maximum power generation ; And
And changing the droop gain of the bidirectional distributed generator by using the derived power sharing rate improvement coefficient value.
The method of claim 12,
The step of deriving the power sharing rate improvement coefficient value,
A droop control method characterized in that the power sharing factor improvement coefficient values in the maximum load power consumption state and the maximum power generation condition of the bidirectional distributed generator are respectively derived based on the voltage sensitivity matrix.
The method of claim 12,
The step of controlling the droop,
Recalculating the voltage sensitivity matrix by reflecting the value of the power sharing factor, and deriving the voltage fluctuation values of each bus in the maximum load and the maximum power generation situation using the recalculated voltage sensitivity matrix, respectively; And
And adjusting the droop gain so that the maximum voltage variation among the voltage variation values in each bus is equal to or less than the set voltage variation width.
The method of claim 11,
The microgrid is a droop control method, characterized in that the direct current.
A computer-readable recording medium product recording a program code for performing the method according to any one of claims 11 to 15.

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