CN107796977A - A kind of three-phase power grid voltage parameter detection method and device - Google Patents

Abstract

The invention belongs to the technical field of power grid, and discloses a three-phase grid voltage parameter detection method and device, which performs Clark transformation on the collected grid voltage signal, establishes an adaptive observer based on the transformed signal, and observes the grid frequency and its positive sequence. Voltage component and negative sequence voltage component, and estimate the magnitude and phase angle of the positive sequence voltage component and negative sequence voltage component of the grid. Specifically include: collecting the three-phase voltage of the grid; performing Clarke transformation to obtain the grid voltage in the coordinate system; building an observer; calculating the positive sequence voltage component and negative sequence voltage component of the grid; calculating the positive sequence voltage component and negative sequence voltage component of the grid amplitude and phase angle. The dynamic response speed is fast, and it still has excellent steady-state accuracy in the case of grid frequency changes. The invention proposes a method for detecting voltage parameters of a three-phase grid, and provides a corresponding hardware circuit, which has fast dynamic response speed and excellent steady-state accuracy under the condition of grid frequency variation.

Description

A method and device for detecting voltage parameters of a three-phase power grid

technical field

The invention belongs to the technical field of power grids, in particular to a method and device for detecting voltage parameters of a three-phase grid.

Background technique

In power grid technology, it is often necessary to detect the positive sequence voltage component, negative sequence voltage component and their corresponding frequency, amplitude and phase angle of the three-phase grid voltage. In the prior art, it is usually realized by phase-locked loop technology. However, due to the use of linearization technology in the phase-locked loop, the response speed of the phase-locked loop is slow. Therefore, when a sudden frequency fault occurs in the power grid, the phase-locked loop cannot quickly and accurately estimate the positive-sequence voltage component and negative-sequence voltage component of the power grid. Thus affecting the control effect of the subsequent controller of the power grid.

To sum up, the problem existing in the prior art is that the existing three-phase grid voltage detection method has a slow dynamic response speed, which affects the performance of three-phase voltage parameter detection.

Contents of the invention

Aiming at the problems existing in the prior art, the present invention provides a method and device for detecting voltage parameters of a three-phase grid.

The present invention is realized in this way, a three-phase power grid voltage parameter detection method performs Clark transformation on the collected power grid voltage signal, establishes an adaptive observer based on the transformed signal, and observes the power grid frequency and its positive sequence voltage component and negative sequence voltage Component, and estimate the magnitude and phase angle of the positive sequence voltage component and negative sequence voltage component of the grid.

Further, the three-phase grid voltage parameter detection method includes the following steps:

Step 1, collecting the three-phase voltage of the power grid;

Step 2, performing Clarke transformation to obtain the grid voltage in the coordinate system;

Step 3, build an observer;

Step 4, calculating the positive sequence voltage component and negative sequence voltage component of the grid;

Step five, calculating the amplitude and phase angle of the positive sequence voltage component and the negative sequence voltage component of the grid.

Further, collect the grid three-phase voltage u _a , u _b , u _c ; perform Clarke transformation:

Get grid voltage u _α , u _β in αβ coordinate system.

Further, build the observer:

and

Among them, x _α1 , x _α2 , x _α3 , x _α4 , x _α5 , x _β1 , x _β2 , x _β3 , x _β4 , x _β5 are the state variables of the observer system, and k ₁ , k ₂ , k ₃ are the selected observations The selection method of coefficients is k ₁ >0, k ₂ >0, k ₃ >0 and the real parts of the two roots of the polynomial s ² +k ₁ s+k ₂ =0 are both less than zero;

The frequency of the grid is:

Further, calculate the positive sequence voltage component and negative sequence voltage component of the grid:

in, is the estimated value of the positive sequence voltage component of the power grid in the αβ coordinate system, is the estimated value of the negative sequence voltage component of the power grid in the αβ coordinate system.

Further, calculate the amplitude and phase angle of the positive sequence voltage component and negative sequence voltage component of the power grid:

in, is the magnitude of the estimated grid positive sequence voltage component, Estimated magnitude of the grid negative-sequence voltage component, Estimated phase angle of the positive sequence voltage component of the grid, Estimated phase angle of the grid negative sequence voltage component.

Another object of the present invention is to provide a three-phase power grid voltage parameter detection device according to the three-phase power grid voltage parameter detection method described in claim 1, said three-phase power grid voltage parameter detection device comprising:

The three-phase voltage sensor collects the grid voltage;

The collected signal is passed through a second-order filter, amplifier, and analog-to-digital converter;

The three-phase network voltage parameter detector estimates positive sequence voltage components, negative sequence voltage components and their frequencies, amplitudes and phase angles.

The advantages and positive effects of the present invention are: the dynamic response speed is fast, and it still has excellent steady-state accuracy under the condition of changing the frequency of the power grid. The invention proposes a method for detecting voltage parameters of a three-phase grid, and provides a corresponding hardware circuit, which has fast dynamic response speed, excellent steady-state accuracy and zero steady-state error under the condition of grid frequency variation.

Description of drawings

Fig. 1 is a flowchart of a method for detecting voltage parameters of a three-phase grid provided by an embodiment of the present invention.

Fig. 2 is a flowchart for realizing a method for detecting voltage parameters of a three-phase grid provided by an embodiment of the present invention.

3 is a schematic structural diagram of a three-phase grid voltage parameter detection device provided by an embodiment of the present invention;

In the figure: 1. Three-phase voltage sensor; 2. Second-order filter; 3. Amplifier; 4. Analog-to-digital converter; 5. Three-phase grid voltage parameter detector.

Detailed ways

In order to make the object, technical solution and advantages of the present invention more clear, the present invention will be further described in detail below in conjunction with the examples. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

The invention has fast dynamic response speed, and still has excellent steady-state precision under the condition of grid frequency variation.

The application principle of the present invention will be described in detail below in conjunction with the accompanying drawings.

As shown in Figure 1, the three-phase power grid voltage parameter detection method provided by the embodiment of the present invention provided by the embodiment of the present invention includes the following steps:

S101: collect the three-phase voltage of the power grid;

S102: Perform Clarke transformation to obtain the grid voltage in the coordinate system;

S103: Build an observer;

S104: Calculate the positive sequence voltage component and the negative sequence voltage component of the grid;

S105: Calculate the amplitude and phase angle of the positive sequence voltage component and the negative sequence voltage component of the grid.

The application principle of the present invention will be further described below in conjunction with the accompanying drawings.

As shown in Figure 2, the three-phase power grid voltage parameter detection method provided by the embodiment of the present invention provided by the embodiment of the present invention includes the following steps:

The first step is to collect the grid three-phase voltage u _a , u _b , u _c ;

The second step is to perform Clarke transformation:

Get grid voltage u _α , u _β in αβ coordinate system;

The third step is to build the observer:

and

Among them, x _α1 , x _α2 , x _α3 , x _α4 , x _α5 , x _β1 , x _β2 , x _β3 , x _β4 , x _β5 are the state variables of the observer system, and k ₁ , k ₂ , k ₃ are the selected observations The selection method is k ₁ >0, k ₂ >0, k ₃ >0 and the real parts of the two roots of the polynomial s ² +k ₁ s+k ₂ =0 are both less than zero.

The frequency of the grid is:

The fourth step is to calculate the positive sequence voltage component and negative sequence voltage component of the grid:

in, is the estimated value of the positive sequence voltage component of the power grid in the αβ coordinate system, is the estimated value of the negative sequence voltage component of the power grid in the αβ coordinate system.

The fifth step is to calculate the amplitude and phase angle of the positive sequence voltage component and the negative sequence voltage component of the grid.

in, is the magnitude of the estimated grid positive sequence voltage component, Estimated magnitude of the grid negative-sequence voltage component, Estimated phase angle of the positive sequence voltage component of the grid, Estimated phase angle of the grid negative sequence voltage component.

As shown in FIG. 3 , the three-phase grid voltage parameter detection device provided by the embodiment of the present invention includes a three-phase voltage sensor 1 , a second-order filter 2 , an amplifier 3 , an analog-to-digital converter 4 , and a three-phase grid voltage parameter detector 5 .

The three-phase voltage sensor 1 collects the grid voltage, and after the collected signal passes through the second-order filter 2, the amplifier 3, and the analog-to-digital converter 4, the three-phase grid voltage parameter detector 5 is used to compare the positive sequence voltage component, negative sequence voltage component and The frequency, amplitude and phase angle are estimated, wherein the three-phase grid voltage parameter detector 5 is composed of a DSP or MCU running a three-phase grid voltage parameter detection method.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention should be included in the protection of the present invention. within range.

Claims (7)

1. A three-phase power grid voltage parameter detection method is characterized in that the three-phase power grid voltage parameter detection method carries out Clark transformation on collected power grid voltage signals, establishes an adaptive observer based on the signals obtained by transformation, observes the power grid frequency and positive sequence voltage components and negative sequence voltage components thereof, and estimates the amplitude and phase angle of the positive sequence voltage components and the negative sequence voltage components of the power grid.

2. The method of detecting three-phase grid voltage parameters of claim 1, comprising the steps of:

step one, collecting three-phase voltage of a power grid;

step two, performing Clarke transformation to obtain the grid voltage under a coordinate system;

step three, constructing an observer;

step four, calculating a positive sequence voltage component and a negative sequence voltage component of the power grid;

and step five, calculating the amplitude and the phase angle of the positive sequence voltage component and the negative sequence voltage component of the power grid.

3. The method for detecting the voltage parameters of the three-phase network according to claim 2, characterized in that the three-phase voltage u of the network is collected_a，u_b，u_c(ii) a Performing Clarke transformation:

<mrow> <mfenced open = "[" close = "]"> <mtable> <mtr> <mtd> <msub> <mi>u</mi> <mi>&amp;alpha;</mi> </msub> </mtd> </mtr> <mtr> <mtd> <msub> <mi>u</mi> <mi>&amp;beta;</mi> </msub> </mtd> </mtr> </mtable> </mfenced> <mo>=</mo> <mfrac> <mn>2</mn> <mn>3</mn> </mfrac> <mfenced open = "[" close = "]"> <mtable> <mtr> <mtd> <mn>1</mn> </mtd> <mtd> <mrow> <mo>-</mo> <mfrac> <mn>1</mn> <mn>2</mn> </mfrac> </mrow> </mtd> <mtd> <mrow> <mo>-</mo> <mfrac> <mn>1</mn> <mn>2</mn> </mfrac> </mrow> </mtd> </mtr> <mtr> <mtd> <mn>0</mn> </mtd> <mtd> <mfrac> <msqrt> <mn>3</mn> </msqrt> <mn>2</mn> </mfrac> </mtd> <mtd> <mrow> <mo>-</mo> <mfrac> <msqrt> <mn>3</mn> </msqrt> <mn>2</mn> </mfrac> </mrow> </mtd> </mtr> </mtable> </mfenced> <mfenced open = "[" close = "]"> <mtable> <mtr> <mtd> <msub> <mi>u</mi> <mi>a</mi> </msub> </mtd> </mtr> <mtr> <mtd> <msub> <mi>u</mi> <mi>b</mi> </msub> </mtd> </mtr> <mtr> <mtd> <msub> <mi>u</mi> <mi>c</mi> </msub> </mtd> </mtr> </mtable> </mfenced> <mo>;</mo> </mrow>

obtaining the grid voltage u under αβ coordinate system_α，u_β。

4. The method for detecting the voltage parameters of the three-phase power grid according to claim 2, characterized in that an observer is constructed:

wherein x is_α1、x_α2、x_α3、x_α4、x_α5、x_β1、x_β2、x_β3、x_β4、x_β5Is an observer system state variable, k₁、k₂、k₃Is a selected observer coefficient selected by k₁＞0、k₂＞0、k₃0 and polynomial s²+k₁s+k₂The real parts of both roots being 0 are less than zero;

the frequency of the grid is:

<mrow> <mover> <mi>&amp;omega;</mi> <mo>^</mo> </mover> <mo>=</mo> <msqrt> <msub> <mi>x</mi> <mrow> <mi>&amp;alpha;</mi> <mn>5</mn> </mrow> </msub> </msqrt> <mo>.</mo> </mrow>

5. the method of claim 2, wherein the positive sequence voltage component and the negative sequence voltage component of the grid are calculated as:

<mrow> <mtable> <mtr> <mtd> <mrow> <msub> <mover> <mi>u</mi> <mo>^</mo> </mover> <mrow> <mi>&amp;alpha;</mi> <mo>_</mo> <mi>p</mi> </mrow> </msub> <mo>=</mo> <mfrac> <mrow> <msub> <mi>x</mi> <mrow> <mi>&amp;alpha;</mi> <mn>3</mn> </mrow> </msub> <mover> <mi>&amp;omega;</mi> <mo>^</mo> </mover> <mo>+</mo> <msub> <mi>x</mi> <mrow> <mi>&amp;beta;</mi> <mn>4</mn> </mrow> </msub> </mrow> <mrow> <mn>2</mn> <mover> <mi>&amp;omega;</mi> <mo>^</mo> </mover> </mrow> </mfrac> <mo>,</mo> <msub> <mover> <mi>u</mi> <mo>^</mo> </mover> <mrow> <mi>&amp;alpha;</mi> <mo>_</mo> <mi>n</mi> </mrow> </msub> <mo>=</mo> <mfrac> <mrow> <msub> <mi>x</mi> <mrow> <mi>&amp;alpha;</mi> <mn>3</mn> </mrow> </msub> <mover> <mi>&amp;omega;</mi> <mo>^</mo> </mover> <mo>-</mo> <msub> <mi>x</mi> <mrow> <mi>&amp;beta;</mi> <mn>4</mn> </mrow> </msub> </mrow> <mrow> <mn>2</mn> <mover> <mi>&amp;omega;</mi> <mo>^</mo> </mover> </mrow> </mfrac> </mrow> </mtd> </mtr> <mtr> <mtd> <mrow> <msub> <mover> <mi>u</mi> <mo>^</mo> </mover> <mrow> <mi>&amp;beta;</mi> <mo>_</mo> <mi>p</mi> </mrow> </msub> <mo>=</mo> <mfrac> <mrow> <mo>-</mo> <msub> <mi>x</mi> <mrow> <mi>&amp;alpha;</mi> <mn>4</mn> </mrow> </msub> <mover> <mi>&amp;omega;</mi> <mo>^</mo> </mover> <mo>+</mo> <msub> <mi>x</mi> <mrow> <mi>&amp;beta;</mi> <mn>3</mn> </mrow> </msub> </mrow> <mrow> <mn>2</mn> <mover> <mi>&amp;omega;</mi> <mo>^</mo> </mover> </mrow> </mfrac> <mo>,</mo> <msub> <mover> <mi>u</mi> <mo>^</mo> </mover> <mrow> <mi>&amp;beta;</mi> <mo>_</mo> <mi>n</mi> </mrow> </msub> <mo>=</mo> <mfrac> <mrow> <msub> <mi>x</mi> <mrow> <mi>&amp;alpha;</mi> <mn>4</mn> </mrow> </msub> <mover> <mi>&amp;omega;</mi> <mo>^</mo> </mover> <mo>+</mo> <msub> <mi>x</mi> <mrow> <mi>&amp;beta;</mi> <mn>3</mn> </mrow> </msub> </mrow> <mrow> <mn>2</mn> <mover> <mi>&amp;omega;</mi> <mo>^</mo> </mover> </mrow> </mfrac> </mrow> </mtd> </mtr> </mtable> <mo>;</mo> </mrow>

wherein,is an estimated value of the positive sequence voltage component of the power grid under the αβ coordinate system,is an estimated value of the negative sequence voltage component of the power grid under the αβ coordinate system.

6. A method of sensing voltage parameters of a three-phase grid according to claim 2, characterized by calculating the amplitude and phase angle of the positive and negative sequence voltage components of the grid:

<mrow> <msub> <mover> <mi>U</mi> <mo>^</mo> </mover> <mi>p</mi> </msub> <mo>=</mo> <msqrt> <mrow> <msubsup> <mover> <mi>u</mi> <mo>^</mo> </mover> <mrow> <mi>&amp;alpha;</mi> <mo>_</mo> <mi>p</mi> </mrow> <mn>2</mn> </msubsup> <mo>+</mo> <msubsup> <mover> <mi>u</mi> <mo>^</mo> </mover> <mrow> <mi>&amp;beta;</mi> <mo>_</mo> <mi>p</mi> </mrow> <mn>2</mn> </msubsup> </mrow> </msqrt> <mo>,</mo> <msub> <mover> <mi>U</mi> <mo>^</mo> </mover> <mi>n</mi> </msub> <mo>=</mo> <msqrt> <mrow> <msubsup> <mover> <mi>u</mi> <mo>^</mo> </mover> <mrow> <mi>&amp;alpha;</mi> <mo>_</mo> <mi>n</mi> </mrow> <mn>2</mn> </msubsup> <mo>+</mo> <msubsup> <mover> <mi>u</mi> <mo>^</mo> </mover> <mrow> <mi>&amp;beta;</mi> <mo>_</mo> <mi>n</mi> </mrow> <mn>2</mn> </msubsup> </mrow> </msqrt> </mrow>

<mrow> <msub> <mover> <mi>&amp;phi;</mi> <mo>^</mo> </mover> <mi>p</mi> </msub> <mo>=</mo> <mi>a</mi> <mi>r</mi> <mi>c</mi> <mi>t</mi> <mi>a</mi> <mi>n</mi> <mrow> <mo>(</mo> <mfrac> <msub> <mover> <mi>u</mi> <mo>^</mo> </mover> <mrow> <mi>&amp;beta;</mi> <mo>_</mo> <mi>p</mi> </mrow> </msub> <msub> <mover> <mi>u</mi> <mo>^</mo> </mover> <mrow> <mi>&amp;alpha;</mi> <mo>_</mo> <mi>p</mi> </mrow> </msub> </mfrac> <mo>)</mo> </mrow> <mo>,</mo> <msub> <mover> <mi>&amp;phi;</mi> <mo>^</mo> </mover> <mi>n</mi> </msub> <mo>=</mo> <mi>a</mi> <mi>r</mi> <mi>c</mi> <mi>t</mi> <mi>a</mi> <mi>n</mi> <mrow> <mo>(</mo> <mfrac> <msub> <mover> <mi>u</mi> <mo>^</mo> </mover> <mrow> <mi>&amp;beta;</mi> <mo>_</mo> <mi>n</mi> </mrow> </msub> <msub> <mover> <mi>u</mi> <mo>^</mo> </mover> <mrow> <mi>&amp;alpha;</mi> <mo>_</mo> <mi>n</mi> </mrow> </msub> </mfrac> <mo>)</mo> </mrow> <mo>;</mo> </mrow>

wherein,is the estimated magnitude of the positive sequence voltage component of the grid,the estimated magnitude of the negative sequence voltage component of the grid,the estimated phase angle of the positive sequence voltage component of the grid,the estimated phase angle of the negative sequence voltage component of the grid.

7. A three-phase grid voltage parameter detection device of the three-phase grid voltage parameter detection method according to claim 1, wherein the three-phase grid voltage parameter detection device comprises:

collecting the voltage of a power grid by a three-phase voltage sensor;

the collected signals pass through a second-order filter, an amplifier and an analog-digital converter;

the three-phase power grid voltage parameter detector estimates the positive sequence voltage component, the negative sequence voltage component, and the frequency, amplitude and phase angle thereof.