CN117990971A - Identification method and identification device for exciting inrush current in MMC-HVDC system converter transformer - Google Patents

Identification method and identification device for exciting inrush current in MMC-HVDC system converter transformer Download PDF

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Publication number
CN117990971A
CN117990971A CN202410078413.5A CN202410078413A CN117990971A CN 117990971 A CN117990971 A CN 117990971A CN 202410078413 A CN202410078413 A CN 202410078413A CN 117990971 A CN117990971 A CN 117990971A
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CN
China
Prior art keywords
current
converter transformer
differential current
actual differential
mmc
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Pending
Application number
CN202410078413.5A
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Chinese (zh)
Inventor
李春华
孙伟生
郭小江
陈怡静
魏世哲
申旭辉
孙栩
王瑾
李铮
胡伟雄
张钧阳
刘旋
彭程
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Huaneng Clean Energy Research Institute
Huaneng Guangdong Shantou Offshore Wind Power Co Ltd
Original Assignee
Huaneng Clean Energy Research Institute
Huaneng Guangdong Shantou Offshore Wind Power Co Ltd
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Priority to CN202410078413.5A priority Critical patent/CN117990971A/en
Publication of CN117990971A publication Critical patent/CN117990971A/en
Pending legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
    • G01R19/165—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values
    • G01R19/16566—Circuits and arrangements for comparing voltage or current with one or several thresholds and for indicating the result not covered by subgroups G01R19/16504, G01R19/16528, G01R19/16533
    • G01R19/16571—Circuits and arrangements for comparing voltage or current with one or several thresholds and for indicating the result not covered by subgroups G01R19/16504, G01R19/16528, G01R19/16533 comparing AC or DC current with one threshold, e.g. load current, over-current, surge current or fault current
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
    • G01R19/10—Measuring sum, difference or ratio
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
    • G01R31/62—Testing of transformers
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/04—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for transformers
    • H02H7/045—Differential protection of transformers
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/36—Arrangements for transfer of electric power between ac networks via a high-tension dc link
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/483—Converters with outputs that each can have more than two voltages levels
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2203/00—Indexing scheme relating to details of circuit arrangements for AC mains or AC distribution networks
    • H02J2203/10—Power transmission or distribution systems management focussing at grid-level, e.g. load flow analysis, node profile computation, meshed network optimisation, active network management or spinning reserve management
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2203/00—Indexing scheme relating to details of circuit arrangements for AC mains or AC distribution networks
    • H02J2203/20—Simulating, e g planning, reliability check, modelling or computer assisted design [CAD]

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Protection Of Transformers (AREA)

Abstract

The invention relates to a method and a device for identifying exciting surge in a converter transformer of an MMC-HVDC system, wherein the method comprises the following steps: after a high-voltage direct-current transmission MMC-HVDC system of the modularized multi-level converter is electrified, acquiring the actual differential current of the converter transformer; determining a fault starting point of the converter transformer according to the actual differential current; after the fault starting point, obtaining the peak value and the valley value of the actual differential current; fitting a sine wave according to the peak value and the valley value; and identifying the exciting inrush current according to the actual differential current and the reference differential current obtained by sine waves at corresponding moments. Therefore, the method can effectively identify the excitation surge current of the converter transformer caused by charging or external faults of the converter transformer of the MMC-HVDC system, and further improve the differential protection function of the converter transformer.

Description

Identification method and identification device for exciting inrush current in MMC-HVDC system converter transformer
Technical Field
The invention relates to the technical field of MMC-HVDC systems, in particular to a method and a device for identifying exciting inrush current in a converter transformer of an MMC-HVDC system.
Background
The extra-high voltage direct current engineering consists of a transmitting-end converter station, a direct current circuit and a receiving-end converter station, and important components of the converter station comprise a converter transformer. The converter transformer occupies an important position in the AC-DC conversion process, exciting inrush current can be generated during no-load charging operation or out-of-zone fault inrush current, and if the exciting inrush current cannot be effectively identified, the differential protection misoperation of the converter transformer can be caused.
In the related art, a second harmonic braking principle and a discontinuous angle principle are generally adopted to rapidly identify the exciting surge, but under the action of the exciting surge in an MMC-HVDC (Modular Multilevel Converter-High Voltage Direct Current, high-voltage direct current transmission of a modularized multi-level converter) converter transformer, the second harmonic of the exciting surge is rapidly attenuated and cannot be braked and protected, so that differential protection misoperation can be caused.
Therefore, how to improve the accuracy of identifying the magnetizing inrush current in the transformer is a current urgent problem to be solved.
Disclosure of Invention
The present invention aims to solve at least one of the technical problems in the related art to some extent.
Therefore, a first object of the present invention is to provide a method for identifying an excitation surge current in a converter transformer of an MMC-HVDC system, which can effectively identify the excitation surge current of the converter transformer caused by charging or an out-of-area fault of the converter transformer of the MMC-HVDC system, thereby improving the differential protection function of the converter transformer.
The second object of the invention is to provide a device for identifying excitation surge current in a converter transformer of an MMC-HVDC system.
A third object of the present invention is to propose an electronic device.
A fourth object of the present invention is to propose a computer readable storage medium.
A fifth object of the invention is to propose a computer programme product.
To achieve the above objective, an embodiment of a first aspect of the present invention provides a method for identifying a magnetizing inrush current in a converter transformer of an MMC-HVDC system, including: after a high-voltage direct-current transmission MMC-HVDC system of the modularized multi-level converter is electrified, acquiring the actual differential current of the converter transformer; determining a fault starting point of the converter transformer according to the actual differential current; after the fault starting point, obtaining a peak value and a valley value of the actual differential current; fitting a sine wave according to the peak value and the valley value; and identifying the exciting inrush current according to the actual differential current and the reference differential current obtained through the sine wave at the corresponding moment.
According to the identification method of the excitation surge current in the MMC-HVDC system converter transformer, after the MMC-HVDC system of the high-voltage direct-current transmission of the modularized multi-level converter is electrified, the actual differential current of the converter transformer is obtained, the fault starting point of the converter transformer is determined according to the actual differential current, the peak value and the valley value of the actual differential current are obtained after the fault starting point, a sine wave is fitted according to the peak value and the valley value, and the excitation surge current is identified according to the actual differential current and the reference differential current obtained through the sine wave at the corresponding moment. Therefore, the method can effectively identify the excitation surge current of the converter transformer caused by charging or external faults of the converter transformer of the MMC-HVDC system, and further improve the differential protection function of the converter transformer.
In addition, the identification method of the excitation surge current in the MMC-HVDC system converter transformer provided by the embodiment of the first aspect of the invention can also have the following additional technical characteristics:
According to one embodiment of the invention, said fitting a sine wave from said peaks and said valleys comprises:
acquiring a set number of the actual differential currents near the peak value and the valley value;
and fitting a sine wave by using a least square method according to the peak value, the valley value and the actual differential current with the set quantity near the peak value and the valley value.
According to one embodiment of the present invention, the identifying the magnetizing inrush current according to the actual differential current and the reference differential current obtained by the sine wave at the corresponding time includes:
calculating a cross correlation coefficient between the actual differential current and a reference differential current obtained through the sine wave at the corresponding moment;
and identifying the excitation inrush current or the fault current in the area according to the cross correlation coefficient.
According to one embodiment of the present invention, the identifying the magnetizing inrush current or the intra-zone fault current according to the cross correlation coefficient includes:
Under the condition that the cross-correlation coefficient is smaller than a set threshold value, determining that the exciting inrush current occurs to the converter transformer;
or if the cross correlation coefficient is greater than or equal to a set threshold, determining that the in-zone fault current of the converter transformer occurs.
To achieve the above object, an embodiment of a second aspect of the present invention provides an apparatus for identifying a magnetizing inrush current in a converter transformer of an MMC-HVDC system, comprising: the first acquisition module is used for acquiring the actual differential current of the converter transformer after the high-voltage direct-current transmission MMC-HVDC system of the modularized multi-level converter is electrified; the determining module is used for determining a fault starting point of the converter transformer according to the actual differential current; the second acquisition module is used for acquiring the peak value and the valley value of the actual differential current after the fault starting point; the fitting module is used for fitting a sine wave according to the peak value and the valley value; and the identification module is used for identifying the exciting inrush current according to the actual differential current and the reference differential current obtained through the sine wave at the corresponding moment.
According to the identification device for the excitation surge current in the MMC-HVDC system converter transformer, the actual differential current of the converter transformer is obtained after the high-voltage direct-current transmission MMC-HVDC system of the modularized multi-level converter is electrified through the first acquisition module, the fault starting point of the converter transformer is determined according to the actual differential current through the determination module, the peak value and the valley value of the actual differential current are obtained after the fault starting point through the second acquisition module, the sine wave is fitted according to the peak value and the valley value through the fitting module, and the excitation surge current is identified through the identification module according to the actual differential current and the reference differential current obtained through the sine wave at corresponding time. Therefore, the device can effectively identify the excitation surge current of the converter transformer caused by charging or external faults of the converter transformer of the MMC-HVDC system, and further improve the differential protection function of the converter transformer.
In addition, the control device for the modularized multi-level converter in the offshore wind power system provided by the embodiment of the second aspect of the invention can also have the following additional technical characteristics:
According to one embodiment of the present invention, the fitting module is configured to fit a sine wave according to the peak value and the valley value, and includes:
acquiring a set number of the actual differential currents near the peak value and the valley value;
and fitting a sine wave by using a least square method according to the peak value, the valley value and the actual differential current with the set quantity near the peak value and the valley value.
According to one embodiment of the present invention, the identification module is configured to identify the magnetizing inrush current according to the actual differential current and a reference differential current obtained by the sine wave at a corresponding time, and includes:
calculating a cross correlation coefficient between the actual differential current and a reference differential current obtained through the sine wave at the corresponding moment;
and identifying the excitation inrush current or the fault current in the area according to the cross correlation coefficient.
According to one embodiment of the present invention, the identifying module is configured to identify that the excitation inrush current or the intra-area fault current is based on the cross correlation coefficient, and includes:
Under the condition that the cross-correlation coefficient is smaller than a set threshold value, determining that the exciting inrush current occurs to the converter transformer;
or if the cross correlation coefficient is greater than or equal to a set threshold, determining that the in-zone fault current of the converter transformer occurs.
To achieve the above object, an embodiment of a third aspect of the present invention further provides an electronic device, including:
at least one processor; and
A memory communicatively coupled to the at least one processor; wherein,
The memory stores instructions executable by the at least one processor to enable the at least one processor to perform the identification method of the magnetizing inrush current in the MMC-HVDC system converter transformer.
According to the battery equipment provided by the embodiment of the invention, by executing the identification method of the excitation surge current in the MMC-HVDC system converter transformer, the excitation surge current of the converter transformer caused by charging or out-of-area faults of the MMC-HVDC system converter transformer can be effectively identified, and the differential protection function of the converter transformer is further improved.
To achieve the above object, an embodiment of a fourth aspect of the present invention further provides a computer readable storage medium, where the computer instructions are configured to cause the computer to execute the method for identifying a magnetizing inrush current in a converter transformer of an MMC-HVDC system.
According to the computer readable storage medium, by executing the identification method of the excitation surge current in the MMC-HVDC system converter transformer, the excitation surge current of the converter transformer caused by charging or out-of-area faults of the MMC-HVDC system converter transformer can be effectively identified, and then the differential protection function of the converter transformer is improved.
To achieve the above object, a fifth test embodiment of the present invention further provides a computer program product, which when executed by an instruction processor in the computer program product, performs the above-mentioned method for identifying a magnetizing inrush current in a converter transformer of an MMC-HVDC system.
According to the computer program product provided by the embodiment of the invention, by executing the identification method of the excitation surge current in the MMC-HVDC system converter transformer, the excitation surge current of the converter transformer caused by charging or out-of-area faults of the MMC-HVDC system converter transformer can be effectively identified, and the differential protection function of the converter transformer is further improved.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and together with the description, serve to explain the principles of the invention.
Fig. 1 is a flowchart of a method of identifying a magnetizing inrush current in a converter transformer of an MMC-HVDC system according to an embodiment of the present invention;
fig. 2 is a block schematic diagram of an identification device of a magnetizing inrush current in a converter transformer of an MMC-HVDC system according to an embodiment of the present invention.
Detailed Description
Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the drawings are illustrative and intended to explain the present invention and should not be construed as limiting the invention.
The identification method and the identification device of the excitation surge current in the MMC-HVDC system converter transformer are described below with reference to the accompanying drawings.
Fig. 1 is a flowchart of a method of identifying a magnetizing inrush current in a converter transformer of an MMC-HVDC system according to an embodiment of the present invention.
It should be noted that, when the MMC-HVDC system converter transformer fails outside the region, the second harmonic may be lower, resulting in a differential protection malfunction. The time difference current of the fault current in the transformer is basically a power frequency sine wave, the fitted sine wave and the original sampling signal have very high similarity, the excitation surge current waveform has a peak wave with a break angle, and the fitted sine wave and the original sampling waveform have low similarity.
As shown in fig. 1, the method for identifying excitation surge current in an MMC-HVDC system converter transformer according to the embodiment of the present invention includes the following steps:
s1, after a high-voltage direct-current transmission MMC-HVDC system of the modularized multi-level converter is electrified, acquiring the actual differential current of the converter transformer.
In step S1, the difference stream is calculated as follows:
Wherein, I AL is the current value after triangle side correction of the converter transformer, I aL、IcL is the actual current value of a phase and a c phase of triangle side of the converter transformer, and K pha is the balance coefficient (is a fixed value) to carry out assignment correction. I oH is a current value after star-shaped side correction of the converter transformer, and I ah、Ibh、Ich is actual current values of star-shaped side a phase, b phase and c phase of the converter transformer.
After I AL and I AH are acquired, a differential current id (t) =i AL(t)-IAH (t) can be obtained.
S2, determining a fault starting point of the converter transformer according to the actual differential current.
For example, when the actual differential current exceeds the set threshold, the converter transformer is considered to be malfunctioning, and this point of time may be regarded as the malfunction starting point of the converter transformer.
And S3, after the fault starting point, acquiring the peak value and the valley value of the actual differential current.
And S4, fitting a sine wave according to the peak value and the valley value.
The implementation process of the step S4 comprises the following steps: the actual differential currents with the set quantity near the peak value and the valley value are firstly obtained (mainly for reducing data acquisition errors), and then a sine wave is fitted by adopting a least square method according to the peak value, the valley value and the actual differential currents with the set quantity near the peak value and the valley value.
The method for specifically constructing the sine wave is as follows:
Assuming the sine wave to be fitted as
Wherein the method comprises the steps of
X (t) is the original sampling value, f is the sine fundamental frequency, A is the sine fundamental amplitude,Is the primary phase of the sine fundamental wave.
The coefficients a and b of the sine wave waveform to be fitted can be determined by means of a least square method. The structural formula is as follows:
in the above formula, N represents the number of points to be calculated, and it should be noted that the number of points in the present invention is not necessarily continuous. Obviously, the minimum value of f (a, b) is required, and the partial derivatives of f (a, b) to a and b respectively are only required to be 0.
And (3) performing least square fitting based on the two formulas to obtain a and b. And back-calculating the fitting sine wave y (t).
Theoretically, the amplitude, frequency and initial phase of the sine wave can be calculated according to the sampling value of 3 points. The approximation is based on the waveform of the half cycle.
F is obtained by performing fourier spectrum analysis from an ac side voltage waveform before a failure. Considering that the system frequency changes slowly, it may be calculated once every interval of time (e.g., 5 minutes).
S5, identifying the exciting inrush current according to the actual differential current and the reference differential current obtained through sine waves at corresponding moments.
The implementation process of the step S5 comprises the following steps: the cross correlation coefficient between the actual differential current and the reference differential current obtained through sine waves at corresponding moments is calculated, and then the exciting inrush current or the fault current in the area is identified according to the cross correlation coefficient. Under the condition that the cross-correlation coefficient is smaller than a set threshold value, determining that excitation surge current occurs to the converter transformer; or under the condition that the cross correlation coefficient is larger than or equal to a set threshold value, determining that the converter transformer generates the in-zone fault current.
As a preferred embodiment of the present invention, the following formula is adopted for the cross-correlation coefficient of the two, namely, the inrush current identification criterion is as follows:
ρ xy(ti) is the cross-correlation coefficient of the original sampled signal x (ti) and the fitted curve y (ti). When the I rho xy(ti) I is equal to 1, the two are strongly related; when |ρ xy(ti) | is equal to 0, the two are completely uncorrelated; the correlation length of the two is used to distinguish between inrush current and fault differential current. When the identification is performed, a threshold is set, and when ρ xy(ti is smaller than the set threshold (such as 0.65), the excitation inrush current is judged, otherwise, the fault current in the area is judged.
In summary, according to the method for identifying the excitation surge current in the MMC-HVDC system converter transformer of the embodiment of the invention, after the high-voltage direct-current transmission MMC-HVDC system of the modularized multi-level converter is electrified, the actual differential current of the converter transformer is obtained, the fault starting point of the converter transformer is determined according to the actual differential current, the peak value and the valley value of the actual differential current are obtained after the fault starting point, the sine wave is fitted according to the peak value and the valley value, and the excitation surge current is identified according to the actual differential current and the reference differential current obtained by the sine wave at the corresponding moment. Therefore, the method can effectively identify the excitation surge current of the converter transformer caused by charging or external faults of the converter transformer of the MMC-HVDC system, and further improve the differential protection function of the converter transformer.
Fig. 2 is a block schematic diagram of an identification device of a magnetizing inrush current in a converter transformer of an MMC-HVDC system according to an embodiment of the present invention.
As shown in fig. 2, an apparatus 200 for identifying a magnetizing inrush current in an MMC-HVDC system converter transformer according to an embodiment of the present invention includes:
A first obtaining module 210, configured to obtain an actual differential current of the converter transformer after the high-voltage direct-current transmission MMC-HVDC system of the modular multilevel converter is powered on;
a determining module 220, configured to determine a fault starting point of the converter transformer according to the actual differential current;
A second obtaining module 230, configured to obtain a peak value and a valley value of the actual differential current after the fault starting point;
a fitting module 240, configured to fit a sine wave according to the peak value and the valley value;
The identification module 250 is configured to identify the magnetizing inrush current according to the actual differential current and a reference differential current obtained by a sine wave at a corresponding time.
According to one embodiment of the present invention, the fitting module 240 is configured to fit a sine wave according to the peak value and the valley value, and includes:
acquiring actual differential currents of set quantity near the peak value and the valley value;
and fitting a sine wave by using a least square method according to the peak value, the valley value and the actual differential current with the set quantity near the peak value and the valley value.
According to one embodiment of the present invention, the identifying module 250 is configured to identify the magnetizing inrush current according to the actual differential current and the reference differential current obtained by the sine wave at the corresponding time, and includes:
Calculating a cross correlation coefficient between the actual differential current and a reference differential current obtained through sine waves at corresponding moments;
and identifying that the exciting inrush current or the fault current in the area is based on the cross correlation coefficient.
According to one embodiment of the present invention, the identifying module 250 is configured to identify that the excitation inrush current or the fault current in the area according to the cross correlation coefficient, and includes:
under the condition that the cross-correlation coefficient is smaller than a set threshold value, determining that exciting inrush current occurs to the converter transformer;
Or under the condition that the cross correlation coefficient is larger than or equal to a set threshold value, determining that the converter transformer generates the in-zone fault current.
It should be noted that details not disclosed in the device for identifying the excitation surge current in the MMC-HVDC system converter transformer in the embodiment of the present invention are combined with details disclosed in the method for identifying the excitation surge current in the MMC-HVDC system converter transformer in the embodiment of the present invention, and detailed descriptions thereof are omitted herein.
According to the identification device for the excitation surge current in the MMC-HVDC system converter transformer, the actual differential current of the converter transformer is obtained after the high-voltage direct-current transmission MMC-HVDC system of the modularized multi-level converter is electrified through the first acquisition module, the fault starting point of the converter transformer is determined according to the actual differential current through the determination module, the peak value and the valley value of the actual differential current are obtained after the fault starting point through the second acquisition module, the sine wave is fitted according to the peak value and the valley value through the fitting module, and the excitation surge current is identified through the identification module according to the actual differential current and the reference differential current obtained through the sine wave at corresponding time. Therefore, the device can effectively identify the excitation surge current of the converter transformer caused by charging or external faults of the converter transformer of the MMC-HVDC system, and further improve the differential protection function of the converter transformer.
Based on the embodiment, the invention further provides electronic equipment.
The electronic equipment of the embodiment of the invention comprises: at least one processor; and a memory communicatively coupled to the at least one processor; the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor, so that the at least one processor can execute the identification method of the excitation surge current in the MMC-HVDC system converter transformer.
According to the battery equipment provided by the embodiment of the invention, by executing the identification method of the excitation surge current in the MMC-HVDC system converter transformer, the excitation surge current of the converter transformer caused by charging or out-of-area faults of the MMC-HVDC system converter transformer can be effectively identified, and the differential protection function of the converter transformer is further improved.
Based on the above embodiments, the present invention also proposes a computer-readable storage medium.
The computer instructions in the computer readable storage medium of the embodiment of the invention are used for enabling a computer to execute the identification method of the excitation surge current in the MMC-HVDC system converter transformer.
According to the computer readable storage medium, by executing the identification method of the excitation surge current in the MMC-HVDC system converter transformer, the excitation surge current of the converter transformer caused by charging or out-of-area faults of the MMC-HVDC system converter transformer can be effectively identified, and then the differential protection function of the converter transformer is improved.
Based on the above embodiments, the present invention also proposes a computer program product.
In an embodiment of the invention, the identification method of the magnetizing inrush current in the MMC-HVDC system converter transformer described above is performed when executed by an instruction processor in a computer program product.
According to the computer program product provided by the embodiment of the invention, by executing the identification method of the excitation surge current in the MMC-HVDC system converter transformer, the excitation surge current of the converter transformer caused by charging or out-of-area faults of the MMC-HVDC system converter transformer can be effectively identified, and the differential protection function of the converter transformer is further improved.
In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, the different embodiments or examples described in this specification and the features of the different embodiments or examples may be combined and combined by those skilled in the art without contradiction.
Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present invention, the meaning of "plurality" means at least two, for example, two, three, etc., unless specifically defined otherwise.
Any process or method descriptions in flow charts or otherwise described herein may be understood as representing modules, segments, or portions of code which include one or more executable instructions for implementing specific logical functions or steps of the process, and additional implementations are included within the scope of the preferred embodiment of the present invention in which functions may be executed out of order from that shown or discussed, including substantially concurrently or in reverse order from that shown or discussed, depending on the functionality involved, as would be understood by those reasonably skilled in the art of the embodiments of the present invention.
Logic and/or steps represented in the flowcharts or otherwise described herein, e.g., a ordered listing of executable instructions for implementing logical functions, can be embodied in any computer-readable medium for use by or in connection with an instruction execution system, apparatus, or device, such as a computer-based system, processor-containing system, or other system that can fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions. For the purposes of this description, a "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transport the program for use by or in connection with the instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of the computer-readable medium would include the following: an electrical connection (electronic device) having one or more wires, a portable computer diskette (magnetic device), a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disc read-only memory (CDROM). In addition, the computer readable medium may even be paper or other suitable medium on which the program is printed, as the program may be electronically captured, via, for instance, optical scanning of the paper or other medium, then compiled, interpreted or otherwise processed in a suitable manner, if necessary, and then stored in a computer memory.
It is to be understood that portions of the present invention may be implemented in hardware, software, firmware, or a combination thereof. In the above-described embodiments, the various steps or methods may be implemented in software or firmware stored in a memory and executed by a suitable instruction execution system. As with the other embodiments, if implemented in hardware, may be implemented using any one or combination of the following techniques, as is well known in the art: discrete logic circuits having logic gates for implementing logic functions on data signals, application specific integrated circuits having suitable combinational logic gates, programmable Gate Arrays (PGAs), field Programmable Gate Arrays (FPGAs), and the like.
Those of ordinary skill in the art will appreciate that all or a portion of the steps carried out in the method of the above-described embodiments may be implemented by a program to instruct related hardware, where the program may be stored in a computer readable storage medium, and where the program, when executed, includes one or a combination of the steps of the method embodiments.
In addition, each functional unit in the embodiments of the present invention may be integrated in one processing module, or each unit may exist alone physically, or two or more units may be integrated in one module. The integrated modules may be implemented in hardware or in software functional modules. The integrated modules may also be stored in a computer readable storage medium if implemented in the form of software functional modules and sold or used as a stand-alone product.
The above-mentioned storage medium may be a read-only memory, a magnetic disk or an optical disk, or the like. While embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and not to be construed as limiting the invention, and that variations, modifications, alternatives and variations may be made to the above embodiments by one of ordinary skill in the art within the scope of the invention.

Claims (10)

1. The method for identifying the excitation surge current in the converter transformer of the MMC-HVDC system is characterized by comprising the following steps of:
After a high-voltage direct-current transmission MMC-HVDC system of the modularized multi-level converter is electrified, acquiring the actual differential current of the converter transformer;
determining a fault starting point of the converter transformer according to the actual differential current;
after the fault starting point, obtaining a peak value and a valley value of the actual differential current;
Fitting a sine wave according to the peak value and the valley value;
And identifying the exciting inrush current according to the actual differential current and the reference differential current obtained through the sine wave at the corresponding moment.
2. The method of claim 1, wherein said fitting a sine wave based on said peaks and said valleys comprises:
acquiring a set number of the actual differential currents near the peak value and the valley value;
and fitting a sine wave by using a least square method according to the peak value, the valley value and the actual differential current with the set quantity near the peak value and the valley value.
3. The method according to claim 1, characterized in that said identifying said magnetizing inrush current from said actual differential current and a reference differential current obtained by means of said sine wave at a corresponding instant comprises:
calculating a cross correlation coefficient between the actual differential current and a reference differential current obtained through the sine wave at the corresponding moment;
and identifying the excitation inrush current or the fault current in the area according to the cross correlation coefficient.
4. A method according to claim 3, wherein said identifying as said magnetizing inrush current or intra-zone fault current based on said cross correlation coefficient comprises:
Under the condition that the cross-correlation coefficient is smaller than a set threshold value, determining that the exciting inrush current occurs to the converter transformer;
or if the cross correlation coefficient is greater than or equal to a set threshold, determining that the in-zone fault current of the converter transformer occurs.
5. An identification device for excitation surge current in a converter transformer of an MMC-HVDC system, comprising:
The first acquisition module is used for acquiring the actual differential current of the converter transformer after the high-voltage direct-current transmission MMC-HVDC system of the modularized multi-level converter is electrified;
the determining module is used for determining a fault starting point of the converter transformer according to the actual differential current;
the second acquisition module is used for acquiring the peak value and the valley value of the actual differential current after the fault starting point;
the fitting module is used for fitting a sine wave according to the peak value and the valley value;
and the identification module is used for identifying the exciting inrush current according to the actual differential current and the reference differential current obtained through the sine wave at the corresponding moment.
6. The apparatus of claim 5, wherein the fitting module is configured to fit a sine wave based on the peak and the valley, comprising:
acquiring a set number of the actual differential currents near the peak value and the valley value;
and fitting a sine wave by using a least square method according to the peak value, the valley value and the actual differential current with the set quantity near the peak value and the valley value.
7. The device according to claim 5, wherein the identifying module is configured to identify the magnetizing inrush current based on the actual differential current and a reference differential current obtained by the sine wave at a corresponding time, and comprises:
calculating a cross correlation coefficient between the actual differential current and a reference differential current obtained through the sine wave at the corresponding moment;
and identifying the excitation inrush current or the fault current in the area according to the cross correlation coefficient.
8. The apparatus of claim 7, wherein the means for identifying, based on the cross correlation coefficient, that the excitation inrush current or the intra-zone fault current is comprises:
Under the condition that the cross-correlation coefficient is smaller than a set threshold value, determining that the exciting inrush current occurs to the converter transformer;
or if the cross correlation coefficient is greater than or equal to a set threshold, determining that the in-zone fault current of the converter transformer occurs.
9. An electronic device, comprising:
at least one processor; and
A memory communicatively coupled to the at least one processor; wherein,
The memory stores instructions executable by the at least one processor to enable the at least one processor to perform the method of identifying magnetizing inrush current in an MMC-HVDC system converter transformer of any of claims 1-4.
10. A computer readable storage medium having stored thereon computer program instructions, which when executed by a processor, implements a method of identifying magnetizing inrush current in an MMC-HVDC system converter transformer according to any of claims 1-4.
CN202410078413.5A 2024-01-18 2024-01-18 Identification method and identification device for exciting inrush current in MMC-HVDC system converter transformer Pending CN117990971A (en)

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CN202410078413.5A CN117990971A (en) 2024-01-18 2024-01-18 Identification method and identification device for exciting inrush current in MMC-HVDC system converter transformer

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202410078413.5A CN117990971A (en) 2024-01-18 2024-01-18 Identification method and identification device for exciting inrush current in MMC-HVDC system converter transformer

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CN117990971A true CN117990971A (en) 2024-05-07

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