A voltage and current transient information acquisition method and device applied to a converter station control protection system

Abstract

The application provides a voltage and current transient information acquisition method and device applied to a converter station control protection system, a single-phase voltage or current signal detected is processed by an alpha-beta signal generation module to generate a single-phase transient signal and a quadrature signal thereof; the single-phase transient signal and the quadrature signal thereof are processed by a rotating coordinate system conversion module to obtain a single-phase voltage or current transient signal in a rotating coordinate system; a transient information discrimination module selects a stable information processing module or a harmonic information processing module to process according to the obtained single-phase voltage or current transient signal, so that single-phase voltage or current transient information of the converter station control protection system is obtained. The application improves the rapidity of the converter station control protection system in acquiring voltage and current transient information; the transient information discrimination module flexibly copes with different working conditions, effectively processes the harmonic problem, and ensures high accuracy of information acquisition.

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 a key node in DC power transmission, converter stations are crucial for the stable operation of the power grid. With the rapid development of renewable energy, the power grid faces increasingly complex dynamic challenges, particularly voltage and current transient oscillations. Therefore, accurately and rapidly acquiring voltage and current transient information has become crucial for ensuring stable DC system operation.

[0003] The traditional voltage and current monitoring methods of converter station control and protection systems are mainly aimed at transient signals in strong power grid environments. They are difficult to effectively deal with abnormal power grid conditions containing multiple harmonics, affecting 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 soft phase-locked loops based on cascaded delay signals and soft phase-locked loops based on second-order generalized integrators. Although these methods can improve the ability to obtain transient information, they require parameter optimization based on specific operating conditions, which limits their scope of application. Therefore, there is an urgent need to study a method and device for monitoring voltage and current transient information of converter station control and protection systems with strong applicability and accuracy to ensure the safe and stable operation of the DC system. Summary of the Invention

[0004] This invention provides a method and device for acquiring voltage and current transient information for use in converter station control and protection systems. This method, through a transient information identification module, flexibly responds to diverse operating conditions, effectively addresses harmonics, and ensures rapid and accurate acquisition of voltage and current transient information. This invention enables timely response to dynamic changes in the power grid, enhances the safety and reliability of the DC system, and provides 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 using an αβ signal generation module, a rotating coordinate system transformation module, a transient information identification module, a stability information processing module, and a harmonic information processing module. The method includes 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 the 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] Where X′ α (k) is the α signal of the single-phase voltage or current; x is the k-th sampled single-phase voltage or current signal;

[0013] The β 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 the harmonic voltage or current; is the phase of single-phase voltage or current; is the phase of the harmonic voltage or current.

[0019] Furthermore, in 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 discrimination 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 discrimination module is:

[0020]

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

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

[0023]

[0024] When the selection flags D and E of the transient information discrimination module are both 1, the single-phase voltage or current transient information is processed by the harmonic information processing module, and when the selection flags D and E are any one of 0, the single-phase voltage or current transient information is processed by the stable information processing module.

[0025] Further, in the step three, the single-phase voltage and current transient information calculation formula in the stable information processing module is as follows:

[0026]

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

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

[0029]

[0030] In the formula, X" d (k) and X" q (k) is single-phase voltage or current transient information under the rotating coordinate system;

[0031] The single-phase voltage and current transient information calculation formula 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 protection system, comprising:

[0034] An αβ signal generation module is configured to process the detected single-phase voltage or current signal to generate a single-phase transient signal and a quadrature signal thereof;

[0035] A rotating coordinate system conversion module is configured to process the single-phase transient signal and the quadrature signal thereof to obtain a single-phase voltage or current transient signal under a rotating coordinate system;

[0036] A transient information discrimination module is configured to select to use a stable information processing module or a harmonic information processing module to process the single-phase voltage or current transient signal, so as to obtain single-phase voltage or current transient information of the converter station control protection system.

[0037] Furthermore, 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] Where X′ α (k) is the α signal of the single-phase voltage or current; x is the k-th sampled single-phase voltage or current signal;

[0040] The β 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 the harmonic voltage or current; is the phase of single-phase voltage or current; is the phase of the harmonic voltage or current.

[0046] Furthermore, 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 discrimination 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 single-phase voltage and current transient information in the stability information processing module is as follows:

[0054]

[0055] Where, is the phase supplement angle;

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

[0057]

[0058] Where, 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;

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

[0060]

[0061] This invention improves the speed with which converter station control and protection systems acquire transient voltage and current information. The transient information identification module flexibly responds to diverse operating conditions, effectively addresses harmonics, and ensures high accuracy in information acquisition. This invention enables timely response to dynamic changes in the power grid, enhancing the safety and reliability of the DC system and providing a strong guarantee for the stable operation of the power system. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 A flowchart of one embodiment of a method for obtaining 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 for a converter station control and protection system provided by the present invention;

[0064] Figure 3 This is a flow chart for obtaining 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 This is the simulation result of obtaining single-phase voltage transient information for the present invention. DETAILED DESCRIPTION

[0067] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying 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 making creative efforts shall fall 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 an αβ signal generation module, a rotating coordinate system transformation module, a transient information identification module, a stability information processing module, and a harmonic information processing module. Figure 2 shown.

[0069] like Figure 1 and Figure 3 As shown, the method includes 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 mainly consists 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 k-th sampled single-phase voltage or current signal.

[0074] The beta signal generation part is calculated according to the following formula:

[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 are 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 the 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: Based on 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, thereby obtaining 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 stability information processing module.

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

[0090]

[0091] Where, is the phase supplement angle.

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

[0093]

[0094] Where, X” d (k) and X” q (k) is the single-phase voltage or current transient information delayed by half a cycle 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] αβ signal generation module, used for processing the detected single-phase voltage or current signal to generate a single-phase transient signal and its orthogonal signal;

[0100] The rotating coordinate system transformation module is used to process the single-phase transient signal and its orthogonal signal to obtain the single-phase voltage or current transient signal in the rotating coordinate system;

[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 0.7 pu to the fault voltage of 1.0 pu containing multiple harmonics at 1 second.

[0104] According to Figure 5The simulation results shown demonstrate the effectiveness of the present invention in acquiring single-phase voltage transient information. When a grid fault occurs at 1 second, the present invention utilizes the transient information identification module to switch from the stable information processing module to the harmonic information processing module, quickly and accurately acquiring single-phase voltage transient information. Furthermore, the present invention minimizes amplitude and phase fluctuations at the moment of the sudden change, and the time required to return to steady state is short, effectively meeting engineering requirements.

[0105] The above description is only a specific embodiment of the present invention, but the scope of protection 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 in the present invention should be covered by the scope of protection 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 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 the single-phase voltage or current transient signal in the rotating coordinate system; Step 3: The transient information identification module selects to use the stability 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; In 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 discrimination 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 discrimination module is: (4)； (5)； Where, X ’ d(q) (k) is the k-th sampled single-phase voltage or current transient information in the rotating coordinate system; The selection flag of the transient information discrimination module is expressed as: (6)； (7)； When the selection flags D and E of the transient information discrimination 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. In step 3, the calculation formula of single-phase voltage and current transient information in the stability information processing module is as follows: (8)； Where, φ x is the phase supplement angle; The signal decomposition formula in the harmonic information processing module is expressed as: (9)； (10)； Where, 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; The calculation formula for single-phase voltage and current transient information in the harmonic information processing module is as follows: (11) 。 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 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: (1)； Where, is the α signal of single-phase voltage or current; x is the single-phase voltage or current signal sampled at the kth time; The β signal generation part is calculated according to the following formula: (2)； 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 converted into a single-phase voltage or current transient signal in a rotating coordinate system through a rotating coordinate system transformation module: (3)； 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; φ is the phase of single-phase voltage or current; φ ml is the phase of the harmonic voltage or current.

4. A voltage and current transient information acquisition device applied to a converter station control and protection system, characterized in that: include: αβ signal generation module, used for processing the detected single-phase voltage or current signal to generate a single-phase transient signal and its orthogonal signal; The rotating coordinate system transformation module is used to process the single-phase transient signal and its orthogonal signal to obtain the single-phase voltage or current transient signal in the rotating coordinate system; A transient information identification module is used to select a stable information processing module or a harmonic information processing module for processing according to the single-phase voltage or current transient signal, thereby obtaining the single-phase voltage or current transient information of the converter station control and protection system; When the transient information determination module selects whether 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: (4)； (5)； Where, X ’ d(q) (k) is the k-th sampled single-phase voltage or current transient information in the rotating coordinate system; The selection flag of the transient information discrimination module is expressed as: (6)； (7)； When the selection flags D and E of the transient information discrimination 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. The calculation formula for single-phase voltage and current transient information in the stability information processing module is as follows: (8)； Where, φ x is the phase supplement angle; The signal decomposition formula in the harmonic information processing module is expressed as: (9)； (10)； Where, 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; The calculation formula for single-phase voltage and current transient information in the harmonic information processing module is as follows: (11) 。 5. The voltage and current transient information acquisition device for a converter station control and protection system according to claim 4, characterized in that: The αβ signal generation module includes an α signal generation part and a β signal generation part, wherein the α signal generation part is calculated according to the following formula: (1)； Where, is the α signal of single-phase voltage or current; x is the k-th sampled single-phase voltage or current signal; The β signal generation part is calculated according to the following formula: (2)； 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.

6. The voltage and current transient information acquisition device for a converter station control and protection system according to claim 5, 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: (3)； 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; φ is the phase of single-phase voltage or current; φ ml is the phase of the harmonic voltage or current.

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