Voltage and current transient information acquisition method and device applied to converter station control and protection system

Abstract

The invention provides a voltage and current transient information acquisition method and device applied to a converter station control and protection system, and the method comprises the steps: carrying out the processing of a detected single-phase voltage or current signal through an alpha-beta signal generation module, so as to generate a single-phase transient signal and an orthogonal signal; processing the single-phase transient signal and the orthogonal signal thereof through a rotating coordinate system conversion module to obtain a single-phase voltage or current transient signal in a rotating coordinate system; and the transient information judgment module selects to use the stability information processing module or the harmonic information processing module for processing according to the obtained single-phase voltage or current transient signal, so that the single-phase voltage or current transient information of the converter station control and protection system is obtained. According to the invention, the rapidness of the converter station control and protection system for acquiring the voltage and current transient information is improved; different working conditions are flexibly handled through the transient information judgment module, the harmonic problem is effectively handled, and high accuracy of information acquisition is ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of converter station control and protection, and in particular to a method and device for acquiring voltage and current transient information applied to a converter station control and protection system. Background Art

[0002] As an important node for DC power transmission, the reliability of converter stations is crucial to the stable operation of the power grid. With the rapid development of new energy, the power grid faces more complex dynamic characteristics challenges, especially the problem of voltage and current transient oscillation. Therefore, how to accurately and quickly obtain voltage and current transient information has become the key to ensure the stable operation of the DC system.

[0003] The traditional voltage and current monitoring methods of the converter station control and protection system are mainly aimed at transient signals in a strong power grid environment. It is difficult to effectively deal with abnormal power grid conditions containing multiple harmonics, which affects the control and protection system's accurate judgment of the actual operating status of the power grid, and may even lead to further deterioration of the oscillation problem. To this end, scholars have proposed a series of methods, such as a soft phase-locked loop based on a cascaded delay signal, a soft phase-locked loop based on a second-order generalized integrator, etc. Although these methods can improve the ability to obtain transient information, they require parameter optimization according to specific operating conditions, which limits their scope of application. Therefore, it is urgent to study a method and device for monitoring voltage and current transient information of a converter station control and protection system with strong applicability and accuracy to ensure the safe and stable operation of the DC system. Summary of the invention

[0004] The present invention provides a method and device for obtaining voltage and current transient information applied to a converter station control and protection system, which can flexibly respond to different working conditions through a transient information identification module, effectively handle harmonic problems, and ensure the rapidity and accuracy of voltage and current transient information acquisition. The present invention can respond to the dynamic changes of the power grid in a timely manner, enhance the safety and reliability of the DC system, and provide a strong guarantee for the stable operation of the power system.

[0005] The objective of the present invention is achieved by the following technical solutions:

[0006] A method for acquiring voltage and current transient information applied to a converter station control and protection system is implemented by using an αβ signal generation module, a rotating coordinate system transformation module, a transient information identification module, a stable information processing module, and a harmonic information processing module. The method comprises the following steps:

[0007] Step 1: Processing the detected single-phase voltage or current signal through the αβ signal generation module to generate a single-phase transient signal and its orthogonal signal;

[0008] Step 2: Process the single-phase transient signal and its orthogonal signal through the rotating coordinate system transformation module to obtain a single-phase voltage or current transient signal in the rotating coordinate system;

[0009] Step 3: The transient information identification module selects to use the stable information processing module or the harmonic information processing module to process the single-phase voltage or current transient signal obtained in step 2, thereby obtaining the single-phase voltage or current transient information of the converter station control and protection system.

[0010] Furthermore, in step 1, the αβ signal generating module includes an α signal generating part and a β signal generating part, wherein the α signal generating part is calculated according to the following formula:

[0011]

[0012] In the formula, X′ α (k) is the α signal of the single-phase voltage or current; x is the single-phase voltage or current signal sampled for the kth time;

[0013] The beta signal generation part is calculated according to the following formula:

[0014]

[0015] Where X' β (k) is the β signal of single-phase voltage or current; ω is the angular frequency of the power system; T s is the transformer sampling time.

[0016] Furthermore, in step 2, the single-phase transient signal and its orthogonal signal are transformed into a single-phase voltage or current transient signal in a rotating coordinate system through a rotating coordinate system transformation module:

[0017]

[0018] Where X' d (k) and X' q (k) is the d-axis and q-axis transient information of the single-phase voltage or current in the rotating coordinate system; X m is the amplitude of single-phase voltage or current; l is the 3rd, 7th and 11th harmonics; X ml is the amplitude of harmonic voltage or current; is the phase of single-phase voltage or current; is the phase of the harmonic voltage or current.

[0019] Further, in step 3, according to the single-phase voltage or current transient information under the rotating coordinate system transformation obtained in step 2, the transient information identification module selects whether to use the stable information processing module or the harmonic information processing module for subsequent processing, wherein the comparison information in the transient information identification module is:

[0020]

[0021] Where X' d(q)(k) is the single-phase voltage or current transient information in the rotating coordinate system;

[0022] The selection flag of the transient information discrimination module is expressed as:

[0023]

[0024] When the selection flags D and E of the transient information identification module are both 1, the harmonic information processing module is used to process the single-phase voltage or current transient information. When either of the selection flags D and E is 0, the single-phase voltage or current transient information is processed by the stable information processing module.

[0025] Furthermore, in step 3, the calculation formula of the single-phase voltage and current transient information in the stability information processing module is as follows:

[0026]

[0027] In the formula, is the phase supplement angle;

[0028] The signal decomposition formula in the harmonic information processing module is expressed as:

[0029]

[0030] In the formula, X” d (k) and X” q (k) is the single-phase voltage or current transient information of the delayed half cycle in the rotating coordinate system;

[0031] The calculation formula for single-phase voltage and current transient information in the harmonic information processing module is as follows:

[0032]

[0033] A voltage and current transient information acquisition device applied to a converter station control and protection system, comprising:

[0034] An αβ signal generating module is used to process the detected single-phase voltage or current signal to generate a single-phase transient signal and its orthogonal signal;

[0035] A rotating coordinate system transformation module is used to obtain a single-phase voltage or current transient signal in a rotating coordinate system by processing a single-phase transient signal and its orthogonal signal;

[0036] The transient information identification module is used to select the stable information processing module or the harmonic information processing module for processing according to the single-phase voltage or current transient signal, so as to obtain the single-phase voltage or current transient information of the converter station control and protection system.

[0037] Further, the αβ signal generating module includes an α signal generating part and a β signal generating part, wherein the α signal generating part is calculated according to the following formula:

[0038]

[0039] In the formula, X′ α (k) is the α signal of the single-phase voltage or current; x is the single-phase voltage or current signal sampled for the kth time;

[0040] The beta signal generation part is calculated according to the following formula:

[0041]

[0042] Where X' β (k) is the β signal of single-phase voltage or current; ω is the angular frequency of the power system; T s is the transformer sampling time.

[0043] Furthermore, the rotating coordinate system transformation module processes the single-phase transient signal and its orthogonal signal to obtain a single-phase voltage or current transient signal in the rotating coordinate system:

[0044]

[0045] Where X' d (k) and X' q (k) is the d-axis and q-axis transient information of the single-phase voltage or current in the rotating coordinate system; X m is the amplitude of single-phase voltage or current; l is the 3rd, 7th and 11th harmonics; X ml is the amplitude of harmonic voltage or current; is the phase of single-phase voltage or current; is the phase of the harmonic voltage or current.

[0046] Further, when the transient information determination module selects to use the stable information processing module or the harmonic information processing module for subsequent processing, the comparison information in the transient information determination module is:

[0047] Y=|X d ' (q) (k)-X d ' (q) (k-1)|(4)

[0048]

[0049] Where X' d(q) (k) is the single-phase voltage or current transient information in the rotating coordinate system;

[0050] The selection flag of the transient information discrimination module is expressed as:

[0051]

[0052] When the selection flags D and E of the transient information identification module are both 1, the harmonic information processing module is used to process the single-phase voltage or current transient information. When either of the selection flags D and E is 0, the single-phase voltage or current transient information is processed by the stable information processing module.

[0053] Furthermore, the calculation formula of the single-phase voltage and current transient information in the stability information processing module is as follows:

[0054]

[0055] In the formula, is the phase supplement angle;

[0056] The signal decomposition formula in the harmonic information processing module is expressed as:

[0057]

[0058] In the formula, X” d (k) and X” q (k) is the single-phase voltage or current transient information of the delayed half cycle in the rotating coordinate system;

[0059] The calculation formula for single-phase voltage and current transient information in the harmonic information processing module is as follows:

[0060]

[0061] The present invention improves the rapidity of the converter station control and protection system in acquiring transient information of voltage and current; the transient information identification module flexibly responds to different working conditions, effectively handles harmonic problems, and ensures high accuracy of information acquisition. The present invention can respond to dynamic changes in the power grid in a timely manner, enhance the safety and reliability of the DC system, and provide a strong guarantee for the stable operation of the power system. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 A schematic diagram of a flow chart of one embodiment of a method for acquiring voltage and current transient information applied to a converter station control and protection system provided by the present invention;

[0063] Figure 2 A schematic diagram of the structure of a voltage and current transient information acquisition device applied to a converter station control and protection system provided by the present invention;

[0064] Figure 3 The flowchart of obtaining the voltage and current transient information of the present invention;

[0065] Figure 4It is the real-time change curve of single-phase voltage in the power grid;

[0066] Figure 5 The simulation results of obtaining single-phase voltage transient information are obtained for the present invention. DETAILED DESCRIPTION

[0067] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0068] The embodiment of the present invention provides a method for obtaining voltage and current transient information applied to a converter station control and protection system, which is implemented by using an αβ signal generation module, a rotating coordinate system transformation module, a transient information determination module, a stable information processing module, and a harmonic information processing module. Figure 2 shown.

[0069] like Figure 1 and Figure 3 As shown, the method comprises the following steps:

[0070] Step 1: Process the detected single-phase voltage or current signal through the αβ signal generation module to generate a single-phase transient signal and its orthogonal signal.

[0071] In step 1, the αβ signal generation module is mainly composed of an α signal generation part and a β signal generation part. The α signal generation part is calculated according to the following formula:

[0072]

[0073] Where X' α (k) is the α signal of the single-phase voltage or current; x is the single-phase voltage or current signal sampled for the kth time.

[0074] The beta signal generation part is calculated as follows:

[0075]

[0076] Where X' β (k) is the β signal of single-phase voltage or current; ω is the angular frequency of the power system; T s is the transformer sampling time.

[0077] Step 2: Use the rotating coordinate system transformation module to obtain the single-phase voltage or current transient signal in the rotating coordinate system.

[0078] In step 2, the single-phase transient signal and its orthogonal signal can be obtained by rotating the coordinate system transformation module:

[0079]

[0080] Where X' d (k) and X' q (k) is the d-axis and q-axis transient information of the single-phase voltage or current in the rotating coordinate system; X m is the amplitude of single-phase voltage or current; l is the 3rd, 7th and 11th harmonics; X ml is the amplitude of harmonic voltage or current; is the phase of single-phase voltage or current; is the phase of the harmonic voltage or current.

[0081] Step 3: According to the single-phase voltage or current transient signal in step 2, the transient information identification module is used to determine whether to use the stable information processing module or the harmonic information processing module for processing, so as to obtain the single-phase voltage or current transient information of the converter station control and protection system.

[0082] In step 3, according to the single-phase voltage or current transient information under the rotating coordinate system transformation in step 2, it is determined whether to use the stable information processing module or the harmonic information processing module for subsequent processing. The comparison information in the transient information discrimination module is

[0083] Y=X d ' (q) (k)-X d ' (q) (k-1)(4)

[0084]

[0085] Where, Y and Z are the contrast information values ​​in the transient information discrimination module; X' d(q) (k) is the single-phase voltage or current transient information in the rotating coordinate system.

[0086] The selection flag of the transient information discrimination module is expressed as

[0087]

[0088] When the selection flags D and E of the transient information identification module are both 1, the harmonic information processing module is used to process the single-phase voltage or current transient information. When either of the selection flags D and E is 0, the single-phase voltage or current transient information is processed by the stable information processing module.

[0089] The single-phase voltage and current transient information formula in the stable information processing module is as follows:

[0090]

[0091] In the formula, is the phase supplement angle.

[0092] The signal decomposition formula in the harmonic information processing module is expressed as

[0093]

[0094] In the formula, X” d (k) and X” q (k) is the single-phase voltage or current transient information of half a period of delay in the rotating coordinate system.

[0095] The single-phase voltage and current transient information formula in the harmonic information processing module is expressed as

[0096]

[0097] In addition, the three-phase voltage and current transient information can also be obtained according to the above technical route.

[0098] like Figure 2 As shown, an embodiment of the present invention further provides a voltage and current transient information acquisition device applied to a converter station control and protection system, comprising:

[0099] An αβ signal generating module is used to process the detected single-phase voltage or current signal to generate a single-phase transient signal and its orthogonal signal;

[0100] A rotating coordinate system transformation module is used to obtain a single-phase voltage or current transient signal in a rotating coordinate system by processing a single-phase transient signal and its orthogonal signal;

[0101] The transient information identification module is used to select the stable information processing module or the harmonic information processing module for processing according to the single-phase voltage or current transient signal, so as to obtain the single-phase voltage or current transient information of the converter station control and protection system.

[0102] Example

[0103] When the power grid contains multiple harmonics, the real-time change curve of single-phase voltage is as follows: Figure 4 As shown in the figure, the grid voltage suddenly changes from the normal operating value of 0.7pu to the fault voltage of 1.0pu containing multiple harmonics at 1 second.

[0104] According to Figure 5The simulation results shown illustrate the effect of the present invention in obtaining single-phase voltage transient information. The power grid fails at 1s. The present invention uses the transient information discrimination module to switch from the stable information processing module to the harmonic information processing module, and quickly and accurately obtains the single-phase voltage transient information. In addition, the amplitude and phase fluctuations of the present invention at the moment of mutation are small, and the time to restore the steady state is short, which effectively meets the engineering requirements.

[0105] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by technicians in this technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for obtaining voltage and current transient information applied to a converter station control and protection system, characterized in that: The method is implemented by using an αβ signal generation module, a rotating coordinate system transformation module, a transient information discrimination module, a stable information processing module, and a harmonic information processing module. The method includes the following steps: Step 1: Processing the detected single-phase voltage or current signal through the αβ signal generation module to generate a single-phase transient signal and its orthogonal signal; Step 2: Process the single-phase transient signal and its orthogonal signal through the rotating coordinate system transformation module to obtain a single-phase voltage or current transient signal in the rotating coordinate system; Step 3: The transient information identification module selects to use the stable information processing module or the harmonic information processing module to process the single-phase voltage or current transient signal obtained in step 2, thereby obtaining the single-phase voltage or current transient information of the converter station control and protection system.

2. The method for obtaining voltage and current transient information applied to a converter station control and protection system according to claim 1, characterized in that: In the step 1, the αβ signal generating module includes an α signal generating part and a β signal generating part, wherein the α signal generating part is calculated according to the following formula: In the formula, X′ α (k) is the α signal of the single-phase voltage or current; x is the single-phase voltage or current signal sampled for the kth time; The beta signal generation part is calculated according to the following formula: Where X' β (k) is the β signal of single-phase voltage or current; ω is the angular frequency of the power system; T s is the transformer sampling time.

3. The method for obtaining voltage and current transient information applied to a converter station control and protection system according to claim 2, characterized in that: In the step 2, the single-phase transient signal and its orthogonal signal are transformed into a single-phase voltage or current transient signal in the rotating coordinate system through a rotating coordinate system transformation module: Where X' d (k) and X' q (k) is the d-axis and q-axis transient information of the single-phase voltage or current in the rotating coordinate system; X m is the amplitude of single-phase voltage or current; l is the 3rd, 7th and 11th harmonics; X ml is the amplitude of harmonic voltage or current; is the phase of single-phase voltage or current; is the phase of the harmonic voltage or current.

4. The method for acquiring voltage and current transient information applied to a converter station control and protection system according to claim 3, characterized in that: In the step 3, according to the single-phase voltage or current transient information obtained in the rotating coordinate system transformation in step 2, the transient information identification module selects whether to use the stable information processing module or the harmonic information processing module for subsequent processing, wherein the comparison information in the transient information identification module is: Y=|X d ′ (q) (k)-X d ′ (q) (k-1)|(4) Where X' d(q) (k) is the single-phase voltage or current transient information in the rotating coordinate system; The selection flag of the transient information discrimination module is expressed as: When the selection flags D and E of the transient information identification module are both 1, the harmonic information processing module is used to process the single-phase voltage or current transient information. When either of the selection flags D and E is 0, the single-phase voltage or current transient information is processed by the stable information processing module.

5. The method for acquiring voltage and current transient information applied to a converter station control and protection system according to claim 3, characterized in that: In step 3, the calculation formula of single-phase voltage and current transient information in the stability information processing module is as follows: In the formula, is the phase supplement angle; The signal decomposition formula in the harmonic information processing module is expressed as: In the formula, X” d (k) and X” q (k) is the single-phase voltage or current transient information of the delayed half cycle in the rotating coordinate system; The calculation formula for single-phase voltage and current transient information in the harmonic information processing module is as follows:

6. A voltage and current transient information acquisition device applied to a converter station control and protection system, characterized in that: include: An αβ signal generating module is used to process the detected single-phase voltage or current signal to generate a single-phase transient signal and its orthogonal signal; A rotating coordinate system transformation module is used to obtain a single-phase voltage or current transient signal in a rotating coordinate system by processing a single-phase transient signal and its orthogonal signal; The transient information identification module is used to select the stable information processing module or the harmonic information processing module for processing according to the single-phase voltage or current transient signal, so as to obtain the single-phase voltage or current transient information of the converter station control and protection system.

7. The voltage and current transient information acquisition device applied to the converter station control and protection system according to claim 6, characterized in that: The αβ signal generating module includes an α signal generating part and a β signal generating part, wherein the α signal generating part is calculated according to the following formula: In the formula, X′ α (k) is the α signal of the single-phase voltage or current; x is the single-phase voltage or current signal sampled for the kth time; The beta signal generation part is calculated according to the following formula: Where X' β (k) is the β signal of single-phase voltage or current; ω is the angular frequency of the power system; T s is the transformer sampling time.

8. The voltage and current transient information acquisition device applied to the converter station control and protection system according to claim 7, characterized in that: The rotating coordinate system transformation module processes the single-phase transient signal and its orthogonal signal to obtain a single-phase voltage or current transient signal in the rotating coordinate system: Where X' d (k) and X' q (k) is the d-axis and q-axis transient information of the single-phase voltage or current in the rotating coordinate system; X m is the amplitude of single-phase voltage or current; l is the 3rd, 7th and 11th harmonics; X ml is the amplitude of harmonic voltage or current; is the phase of single-phase voltage or current; is the phase of the harmonic voltage or current.

9. The voltage and current transient information acquisition device applied to the converter station control and protection system according to claim 8, characterized in that: When the transient information determination module selects to use the stable information processing module or the harmonic information processing module for subsequent processing, the comparison information in the transient information determination module is: Y=|X d ′ (q) (k)-X d ′ (q) (k-1)|(4) Where X' d(q) (k) is the single-phase voltage or current transient information in the rotating coordinate system; The selection flag of the transient information discrimination module is expressed as: When the selection flags D and E of the transient information identification module are both 1, the harmonic information processing module is used to process the single-phase voltage or current transient information. When either of the selection flags D and E is 0, the single-phase voltage or current transient information is processed by the stable information processing module.

10. The voltage and current transient information acquisition device applied to the converter station control and protection system according to claim 8, characterized in that: The calculation formula of single-phase voltage and current transient information in the stability information processing module is as follows: In the formula, is the phase supplement angle; The signal decomposition formula in the harmonic information processing module is expressed as: In the formula, X” d (k) and X” q (k) is the single-phase voltage or current transient information of the delayed half cycle in the rotating coordinate system; The calculation formula for single-phase voltage and current transient information in the harmonic information processing module is as follows:

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