KR20190033673A - System and method for controlling grid-connected system of distributed generation using integral state feedback controller - Google Patents

Abstract

The present invention relates to a control system for a distributed power system linkage device using an integrating state feedback controller, and a method therefor. According to the present invention, the control system for a distributed power system linkage device using an integrating state feedback controller comprises: a state observer which individually receives voltages and currents of a system-side individually measured by a voltage sensor and a current sensor, and individually estimates an inverter-side current of the distributed power system linkage device and a capacitor voltage of an LCL filter on the basis of the received voltages and currents; an integrating state feedback controller which generates q axis and d axis reference voltages for controlling the inverter of the distributed power system linkage device by using state equations after receiving the inverter-side current and the capacitor voltage of the LCL filter estimated by the state observer and receiving the system-side current measured by the current sensor; and a space vector pulse width modulator which receives the q axis and d-axis reference voltages generated by the integrating state feedback controller so as to perform pulse width modulation processing and outputs a signal for controlling a plurality of semiconductor switching elements in the inverter to the inverter side. According to the present invention, the complexity of the system is simplified.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control system and method for a distributed power grid interconnecting apparatus using an integral type state feedback controller,

The present invention relates to a control system and method for a distributed power grid interconnecting apparatus, and more particularly, to an integrated state feedback controller for effective control of a grid interconnecting apparatus, thereby simplifying system complexity and reducing system design cost And more particularly to a control system and method for a distributed power grid interconnecting apparatus using an integral type state feedback controller.

Demand for grid-connected equipment is increasing dramatically due to the increase in the generation of distributed grid power using micro grid structure and renewable energy. In order to connect such a grid-connecting device with the power grid, it is necessary to effectively reduce the harmonics and ensure the quality of the grid inrush current. For this purpose, LCL filters are generally adopted.

Although the LCL filter combined with the grid linkage is effective in reducing the harmonics with a small size, it causes the complexity of the controller design and the high systematic modeling of the system model by increasing the state of the system. In order to cope with this, conventionally, a method of controlling the current of the inductor, the voltage of the capacitor, and the current of the inductor again in a dependent structure is used. However, such a conventional control method has advantages in a non-discrete switching and the like, but a separate controller must be designed, and the inverter side current, the voltage of the capacitor, and the system side current must be measured for the feedback control configuration of each controller.

[0006] On the other hand, Japanese Laid-Open Patent Publication No. 10-2011-0013221 (Patent Document 1) discloses a " grid-connected inverter apparatus and a control method thereof ", and a control method of the grid- Wherein the inverter circuit is connected to the power system through a series circuit comprising a current limiting resistor and a first switch and an open / close circuit comprising a current limit resistor of the series circuit or a second switch connected in parallel to the series circuit, And a filter capacitor is disposed between the switching circuit and the switching circuit, wherein the output current of the inverter circuit is changed until the second switch is turned on after the first switch is turned on And the output current flowing between the filter capacitor and the open / close circuit becomes zero Characterized in that the lock control feedback.

In the case of Patent Document 1, since the inverter circuit is controlled so that the output current of the inverter circuit becomes zero until the second switch is turned on after the first switch is turned on, the second switch is turned on It is possible to prevent an inrush current from flowing into the capacitor for the filter when the inrush current is cut off. As a result, there is an advantage in that it is unnecessary to use a current limiting resistor having a large power rating or to prepare a switch having a large current rating . However, this also uses a method of controlling the current of the inductor and the voltage of the capacitor separately, so that a separate controller must be designed. In order to configure the feedback control of each controller, the inverter side current and the voltage of the capacitor There is a drawback that it must be measured.

Open Patent Publication No. 10-2011-0013221 (Published Feb., 2011)

SUMMARY OF THE INVENTION The present invention has been made in order to overcome the problems of the prior art as described above, and it is an object of the present invention to overcome the disadvantage of separately designing three controllers by introducing an integral type state feedback controller for effective control of the grid- , It is possible to design a grid connection device that meets the system specifications. Instead of measuring both the inverter side current, the capacitor voltage and the system side current, only the grid side current is measured and the remaining components are estimated through the state observer, And an object of the present invention is to provide a control system and method for a distributed power grid interconnecting apparatus using an integrated state feedback controller that can simplify the complexity of the system and reduce the system design cost.

According to another aspect of the present invention, there is provided a control system for a distributed power grid interconnecting apparatus using an integrated state feedback controller,

A system for controlling a distributed power grid interconnector applied to a distributed power grid interconnector,

A state observer for receiving a voltage and a current on the grid side respectively measured by the voltage sensor and the current sensor, respectively, and estimating a capacitor voltage of the LCL filter based on the inverter side current of the distributed power grid interconnecting device and the LCL filter;

And a controller for controlling the inverter of the distributed power grid interconnecting device by using the state equation, receiving the inverter side current estimated by the state observer, the capacitor voltage of the LCL filter, and the system side current measured by the current sensor, an integral type state feedback controller for generating a d-axis reference voltage; And

A spatial vector pulse width modulator for receiving the q and d axis reference voltages generated by the integral type state feedback controller and performing a pulse width modulation process and outputting a signal for controlling the plurality of semiconductor switching elements in the inverter to the inverter side This is characterized by the fact that

The system further includes an SRF-PLL (Synchronous Reference Frame-Phase Locked Loop) that receives the system voltage measured by the voltage sensor and generates a system voltage phase angle? .

According to another aspect of the present invention, there is provided a method of controlling a distributed power grid interconnecting apparatus using an integrated state feedback controller,

A method for controlling a distributed power grid interconnecting device based on a control system of a distributed power grid interconnecting device using an integrated state feedback controller including a state observer, an integrated state feedback controller, and a spatial vector pulse width modulator,

a) measuring voltage and current on the system side by a voltage sensor and a current sensor, respectively;

b) constructing a state observer by the control system using the measured grid side voltage and current information;

c) receiving a system side voltage and a current respectively measured by the voltage sensor and the current sensor by the state observer, and estimating a q, d-axis inverter side current and a capacitor voltage of the LCL filter of the distributed power grid interconnector step;

d) receiving the q, d-axis inverter side current and the capacitor voltage of the LCL filter estimated by the state observer by the integral type state feedback controller and the q, d-axis system side current measured by the current sensor, Generating a q, d axis reference voltage for inverter control using an equation; And

e) providing the q, d-axis reference voltage generated by said integral state feedback controller by said control system to the distributed power grid interconnector for control of the distributed power grid interconnector, have.

Here, the q-th, d-axis inverter-side current and the capacitor voltage of the LCL filter, which are estimated by the state observer in step c), can be expressed by the following equation.

The q, d-axis reference voltage generated by the integral type state feedback controller in step d) may be expressed by the following equation.

According to the present invention, by introducing the integral type state feedback controller, it is possible to overcome the disadvantage of separately designing three controllers and to design a grid coupling device that meets system specifications in a systematic manner, and the inverter side current, Instead of measuring both the voltage and the system side current, only the system side current is measured and the remaining components are estimated through the state observer and used as a feedback signal, which simplifies the system complexity and reduces system design cost.

FIG. 1 is a diagram schematically showing a configuration of a control system of a distributed power supply system linking apparatus using an integrated state feedback controller according to the present invention.
FIG. 2 is a diagram showing the internal configuration of the integrated state feedback controller of the control system of the distributed power supply system linking apparatus shown in FIG. 1. FIG.
3 is a flowchart illustrating a method of controlling a distributed power grid interconnecting apparatus using an integrated state feedback controller according to the present invention.
FIG. 4 is a diagram showing a simulation result of a three-phase variable of the integral type state feedback controller of the control system of the distributed power supply system coupling device shown in FIG.
5 is a diagram showing simulation results of the q, d-axis system current, the estimated inverter side current, and the capacitor voltage by the integrated state feedback controller of the control system of the distributed power supply system linkage apparatus shown in Fig.

The terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms and the inventor can properly define the concept of the term to describe its invention in the best way Should be construed in accordance with the principles and meanings and concepts consistent with the technical idea of the present invention.

Throughout the specification, when an element is referred to as " comprising ", it means that it can include other elements as well, without excluding other elements unless specifically stated otherwise. Also, the terms " part, " " module, " and " device "Lt; / RTI >

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

1 is a diagram schematically showing a configuration of a control system of a distributed power grid interconnecting apparatus using an integral type state feedback controller according to an embodiment of the present invention.

1, a control system 140 of a distributed power grid interconnecting apparatus using an integrated state feedback controller according to the present invention is a system for controlling a distributed power grid interconnecting apparatus applied to a distributed power grid interconnecting apparatus, A state observer 141, an integral type state feedback controller 142, and a spatial vector pulse width modulator 143. [

The state observer 141 compares the system side voltage e _abc and the current i _{2 abc} measured by the voltage sensor and the current sensor (not shown) with a three-phase alternating voltage and a current q, a d-axis direct voltage and a current (I 1 _q , i 1 _d ) of the inverter 110 of the distributed power grid interconnector and the capacitor voltages v _cq and v _cd of the LCL filter 120 are estimated based on the received _signals , do. This is explained later.

The integral type state feedback controller 142 compares the current i _iq and i _1d of the inverter 110 estimated by the state observer 141 with the capacitor voltages v _cq and v _cd of the LCL filter 120, A q, d-axis reference voltage (v ^* _q , i2d) for controlling the inverter 110 of the distributed power supply system linkage device using the state equation and receiving the system side currents (i _2q , i _2d ) v ^* _d ). I will explain it again later.

The spatial vector pulse width modulator 143 receives the q and d axis reference voltages v ^* _q and v ^* _d generated by the integral type state feedback controller 142 and performs pulse width modulation on the q and d axis reference voltages v ^* To the inverter 110, a signal for controlling a plurality of (for example, six) semiconductor switching elements (for example, a MOSFET, an IGBT, etc.)

The control system 140 of the distributed power grid interconnecting apparatus using the integral type state feedback controller according to the present invention having the above-described configuration preferably controls the system voltage ( _eq , e _d) a can input receiving further includes a grid voltage phase angle (θ), SRF-PLL (Synchronous Reference Frame-phase Locked Loop) (144) provided by the above space vector pulse-width modulator 143 generates a .

The state observer 141, the integrated state feedback controller 142, the spatial vector pulse width modulator 143, and the SRF-PLL 144 may be configured as one software program. The control system 140 of the distributed power grid interconnecting apparatus using the integrated state feedback controller according to the present invention includes a state observer 141, an integral state feedback controller 142, a spatial vector pulse width modulator 143, -PLL 144 may be configured as one computer system on which respective software programs are installed. The state observer 141, the integrated state feedback controller 142, the spatial vector pulse width modulator 143, and the SRF-PLL 144 are not limited to software programs. In some cases, And may be installed inside or outside the computer.

FIG. 2 is a diagram showing the internal configuration of the integrated state feedback controller of the control system of the distributed power supply system linking apparatus shown in FIG. 1. FIG.

2, the integral type state feedback controller 142 compares a value obtained by adding the integral gain Ki to the reference current and a value obtained by adding the system matrix D to a value in which the input matrix B is reflected to the value A value obtained by reflecting the output matrix C to the output value, and a system matrix D value are applied to a pre-designed state space model to process the feedback gain Kx, And an observer for outputting an output signal.

Hereinafter, a method of controlling the distributed power grid interconnecting apparatus based on the control system of the distributed power grid interconnecting apparatus using the integrated state feedback controller according to the present invention having the above configuration will be described.

3 is a flowchart illustrating a method of controlling a distributed power grid interconnecting apparatus using an integrated state feedback controller according to an embodiment of the present invention.

3, a method of controlling a distributed power grid interconnecting apparatus using an integrated state feedback controller according to the present invention includes a state observer 141, an integral state feedback controller 142, A method for controlling a distributed power grid interconnecting device based on a control system (140) of a distributed power grid interconnecting device using an integral type state feedback controller including a modulator (143) (which can be regarded as a kind of computer system) Voltage and current on the side of the system power supply (hereinafter, referred to as 'system') 130 are measured by a sensor and a current sensor (not shown) (step S301).

Then, the state observer 141 is configured by the control system 140 (computer system) of the distributed power grid interconnecting apparatus of the present invention using the measured voltage and current information of the system 130 (step S302) . Here, the state observer 141 may be configured using a state space model as a continuous model. And such a state space model can be discretized using approximate results of state equations in a discrete model.

,

)와 LCL 필터(120)의 커패시터 전압(

,

)을 추정한다(단계 S303). When the configuration of the state observer 141 is completed in this way, the configured state observer 141 receives the voltage and current on the system 130 side measured by the voltage sensor and the current sensor, respectively, Q, the current on the d-axis inverter 110 side (

,

And the capacitor voltage of the LCL filter 120

,

) (Step S303).

,

)와 LCL 필터(120)의 커패시터 전압 (

,

)은 다음의 수식 관계로 표현될 수 있다.Here, the current of the q, d-axis inverter 110 of the distributed power grid linkage device estimated by the state observer 141

,

And the capacitor voltage of the LCL filter 120

,

) Can be expressed by the following equation.

Here, a ₃₁ , ... a ₃₆ , a ₄₁ , ... a ₄₆ , a ₅₁ , ... a ₅₆ , a ₆₁ , ... a ₆₆ are components of the system matrix A in the grid- and, i ₂ ^q, i ₂ ^d is the grid side q, d-axis _{current, b 31, b 32, b} 41, b 42, b 51, b 52, b 61, b 62 are in the system interconnection inverter discrete model D ₃₁ , d ₃₂ , d ₄₁ , d ₄₂ , d ₅₁ , d ₅₂ , d ₆₁ , d ₆₂ are components of the system matrix B and v _i ^q and v _i ^d are the q and d- E _q and e _d are the system side q and d axis voltages and g ₃₁ , g ₃₂ , g ₄₁ , g ₄₂ , g ₅₁ , g ₅₂ , g ₆₁ and g ₆₂ are components of the grid voltage matrix in the inverter discrete model, Is the gain value of the observer determined by the pole arrangement method.

,

)와 LCL 필터(120)의 커패시터 전압(

,

)의 추정이 완료되면, 적분형 상태궤환 제어기(142)에 의해 상태 관측기(141)에 의해 추정된 q, d축 인버터 (110) 측 전류(

,

)와 LCL 필터(120)의 커패시터 전압(

,

)과, 상기 전류 센서에 의해 측정된 q, d축 계통측 전류(i_2q, i_2d)를 입력받아 상태방정식(예를 들면, 8차 상태방정식)을 이용하여 인버터 제어를 위한 q, d축 기준 전압(v^* _q, v^* _d)을 생성한다(단계 S304). 여기서, 상기 적분형 상태궤환 제어기에 의해 생성되는 q, d축 기준 전압(v^* _q, v^* _d)은 다음의 수식 관계로 표현될 수 있다.As described above, the q, d-axis inverter 110 side current (

,

And the capacitor voltage of the LCL filter 120

,

The estimated q by the state observer 141 by the integral type state feedback controller 142 and the current on the d-axis inverter 110 side (

,

And the capacitor voltage of the LCL filter 120

,

And q and d axes for controlling the inverter by using a state equation (for example, an eighth order state equation) by receiving the q, d-axis system side currents i _2q and i _2d measured by the current sensor, And generates a reference voltage (v ^* _q , v ^* _d ) (step S304). Here, the q, d-axis reference voltages (v ^* _q , v ^* _d ) generated by the integral type state feedback controller can be expressed by the following equation.

Here, k ₁₁ , ..., k ₁₆ , k ₂₁ , ... k ₂₆ are state control gain values determined by the pole arrangement method, and s ₁₁ , s ₁₂ , s ₂₁ , s ₂₂ are determined by the pole arrangement method It is the integral state gain value.

When the generation of the q, d axis reference voltages (v ^* _q , v ^* _d ) is completed, the control system 140 (computer system) controls the integral type state feedback controller Q, and d-axis reference voltages (v ^* _q , v ^* _d ) generated by the q-axis and the q-axis reference voltages to the distributed power grid interconnector (step S305). At this time, the space vector pulse width modulator 143 receives the q, d-axis reference voltages (v ^* _q , v ^* _d ) generated by the integral type state feedback controller 142 and performs pulse width modulation processing And providing the applied reference voltage to the inverter 110 of the distributed power grid interconnector.

Hereinafter, the state equations and the system equations used in the present invention will be described in detail with respect to the inverter of the distributed power grid interconnecting apparatus.

The inverter 110 of the distributed power grid interconnector may be represented by the following equation of state.

는 계통측 전류, 인버터측 전류, 커패시터 전압을 각각 나타내고, u와 e는 시스템 입력 값과 계통측 전압값을 나타낸다. 이상과 같이 언급된 모든 값은 동기좌표계로 표현된다.here,

Represents the system side current, the inverter side current, and the capacitor voltage, and u and e represent the system input value and the system side voltage value, respectively. All values mentioned above are expressed in the synchronous coordinate system.

In the above state equation, A represents a system matrix, B represents an input matrix, D represents a systematic input matrix, and C represents an output matrix, and can be expressed by the following matrix expression.

Since each of the above matrices is modeled on the assumption of a continuous time, it is discretized by using the bilinear approximation approach as shown below for the practical system.

The following shows the system matrix, input matrix, and systematic matrix newly defined by discretizing the continuous time model.

Finally, the system equation can be represented by discretization as follows.

Next, you need to set system input values to control the above system. First, we use the following matrix P _C to check the system's controllability.

The system is controllable when the rank (rank) of the above matrix is equal to the system order (n), and when the controllability is judged, the gain matrix of the system is obtained through the pole arrangement method as follows.

If all the roots of the above characteristic equation are within the unit circle, then the closed-loop system is stable. Given Ad and Bd matrices for arbitrary initial conditions, K is always present in order to place all poles of the closed-loop system in the unit circle. The condition is that the system is fully controllable. The above equation gives the following gain matrix K:

의 상태제어를 위한 이득행렬이고, K_i는 출력전류의 오차 값을 줄여주기 위한

즉, 출력값과 기준값의 적분 이득행렬이다. r은 명령값(reference)을 의미하고, y는 출력전류(계통측 전류)를 의미한다. Here, K is

And K _i is a gain matrix for reducing the error of the output current

That is, it is an integral gain matrix of the output value and the reference value. r denotes a command value, and y denotes an output current (system side current).

On the other hand, the system equation including the observer can be expressed by the following equation.

이다. 이때, u는 시스템 입력값이고, y는 시스템 출력값이다. 여기서, 관측기(상태 관측기(141))의 목적은

에 따라

가 되도록 추정값

를 제공함에 있다. In the above equation, G is the observer gain matrix, which is the value determined during the observer design process. The inputs of the observer are u and y and the output is

to be. Where u is the system input value and y is the system output value. Here, the purpose of the observer (state observer 141)

Depending on the

Lt; / RTI >

.

의 계수(랭크, rank)가 시스템 차수(n)와 같을 때 시스템은 완전한 관측이 가능하다. 시스템이 완전한 관측이 가능하면 추적 오차가 점근적으로 안정되는 행렬 G를 항상 찾을 수 있다. 위에서의 시스템 이득 행렬과 유사한 방식으로 다음의 특성 방정식

가 단위원 내부에 모든 근을 가지면

에 따라

를 만족하도록 하는 다음과 같은 행렬 G를 찾을 수 있다.Observers are likewise likewise probabilistic matrices

The system is fully observable when the rank (rank) of the system is equal to the system order (n). If the system is capable of full observations, it can always find a matrix G whose tracking error is asymptotically stable. In a manner similar to the system gain matrix above, the following characteristic equation

Has all the roots inside the unit circle

Depending on the

The following matrix G can be found.

Meanwhile, FIG. 4 is a diagram showing a simulation result of a three-phase variable of the integral type state feedback controller of the control system of the distributed power supply system coupling device shown in FIG.

Referring to FIG. 4, (A) shows a three-phase system side current waveform, (B) shows a three-phase inverter side current waveform and (C) shows a three-phase capacitor voltage waveform. As described above, the inverter side current and the capacitor voltage waveform by the control system of the distributed power supply system using the integrated state feedback controller according to the present invention can be realized by integrating the state of the inverter with the integrated state feedback controller without installing separate sensors on the inverter side and the capacitor side. It can be seen that it is almost similar to the measured waveform using the sensor.

5 is a diagram showing simulation results of the q, d-axis system current, the estimated inverter side current, and the capacitor voltage by the integrated state feedback controller of the control system of the distributed power supply system linkage apparatus shown in Fig.

Referring to Figure 5, (A) a current in the grid side (i _2q, i _2d) and the estimated state will showing a current ^{_{(i 2q e, i 2d e}} ) waveform, (B) an inverter-side current (i _1q of , a will showing the i _1d) and the estimated state current ^{_{(i 1q e, i 1d e}} ) waveform, (C) a capacitor voltage (v _cq, v _cd) and the estimated state voltage (v _cq ^e, v _cd ^e) waveform .

As can be seen from the above, it can be seen that the actual current and voltage waveforms are almost identical to the current and voltage waveforms estimated by applying the present invention, respectively.

As described above, the control system and method of the distributed power supply system linking apparatus using the integral type state feedback controller according to the present invention overcomes the disadvantage of separately designing three controllers by introducing the integral type state feedback controller, Method, it is possible to design a system linkage device that meets system specifications.

In addition, instead of measuring both the inverter side current, capacitor voltage and system side current, only the system side current is measured and the remaining components are estimated through the state observer and used as a feedback signal to simplify the system complexity and reduce the system design cost There is an advantage.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but many variations and modifications may be made without departing from the spirit and scope of the invention. Be clear to the technician. Accordingly, the true scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of the same should be construed as being included in the scope of the present invention.

110: inverter 120: LCL filter
130: system power supply 141: state observer
140: (invention) control system of distributed power grid interconnection device
142: Integral type state feedback controller 143: Space vector pulse width modulator
144: SRF-PLL

Claims (5)

A system for controlling a distributed power grid interconnector applied to a distributed power grid interconnector,
A state observer for receiving a voltage and a current on the grid side respectively measured by the voltage sensor and the current sensor, respectively, and estimating a capacitor voltage of the LCL filter based on the inverter side current of the distributed power grid interconnecting device and the LCL filter;
And a controller for controlling the inverter of the distributed power grid interconnecting device by using the state equation, receiving the inverter side current estimated by the state observer, the capacitor voltage of the LCL filter, and the system side current measured by the current sensor, an integral type state feedback controller for generating a d-axis reference voltage; And
A spatial vector pulse width modulator for receiving the q and d axis reference voltages generated by the integral type state feedback controller and performing a pulse width modulation process and outputting a signal for controlling the plurality of semiconductor switching elements in the inverter to the inverter side Control System for Distributed Power System Linkage System Using Integral State Feedback Controller.
The method according to claim 1,
And an SRF-PLL (Synchronous Reference Frame-Phase Locked Loop) that receives the system voltage measured by the voltage sensor and generates a system voltage phase angle? Control System of Distributed Power System Linkage System Using State Feedback Controller.
A method for controlling a distributed power grid interconnecting device based on a control system of a distributed power grid interconnecting device using an integrated state feedback controller including a state observer, an integrated state feedback controller, and a spatial vector pulse width modulator,
a) measuring voltage and current on the system side by a voltage sensor and a current sensor, respectively;
b) constructing a state observer by the control system using the measured grid side voltage and current information;
c) receiving a system side voltage and a current respectively measured by the voltage sensor and the current sensor by the state observer, and estimating a q, d-axis inverter side current and a capacitor voltage of the LCL filter of the distributed power grid interconnector step;
d) receiving the q, d-axis inverter side current and the capacitor voltage of the LCL filter estimated by the state observer by the integral type state feedback controller and the q, d-axis system side current measured by the current sensor, Generating a q, d axis reference voltage for inverter control using an equation; And
e) providing, by the control system, the q, d-axis reference voltage generated by the integral state feedback controller to the distributed power grid interconnector for control of the distributed power grid interconnector, Control Method of Distributed Power System Linkage Device Using.
The method of claim 3,
Wherein the q-th, d-axis inverter-side current and the capacitor voltage of the LCL filter of the distributed power supply linkage device estimated by the state observer in the step c) are represented by the following equation: Method of controlling a distributed power grid interconnecting device.

Here, a ₃₁ , ... a ₃₆ , a ₄₁ , ... a ₄₆ , a ₅₁ , ... a ₅₆ , a ₆₁ , ... a ₆₆ are components of the system matrix A in the grid- and, i ₂ ^q, i ₂ ^d is the grid side q, d-axis _{current, b 31, b 32, b} 41, b 42, b 51, b 52, b 61, b 62 are in the system interconnection inverter discrete model D ₃₁ , d ₃₂ , d ₄₁ , d ₄₂ , d ₅₁ , d ₅₂ , d ₆₁ , d ₆₂ are components of the system matrix B and v _i ^q and v _i ^d are the q and d- E _q and e _d are the system side q and d axis voltages and g ₃₁ , g ₃₂ , g ₄₁ , g ₄₂ , g ₅₁ , g ₅₂ , g ₆₁ and g ₆₂ are components of the grid voltage matrix in the inverter discrete model, Is the gain value of the observer determined by the pole arrangement method.
The method of claim 3,
Wherein the q, d axis reference voltage generated by the integral type state feedback controller in the step (d) is expressed by the following equation: < EMI ID = 1.0 >

Here, k ₁₁ , ..., k ₁₆ , k ₂₁ , ... k ₂₆ are state control gain values determined by the pole arrangement method, and s ₁₁ , s ₁₂ , s ₂₁ , s ₂₂ are determined by the pole arrangement method It is the integral state gain value.

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