CN116755018A - Method and system for measuring distributed capacitance of primary winding of electromagnetic voltage transformer - Google Patents

Method and system for measuring distributed capacitance of primary winding of electromagnetic voltage transformer Download PDF

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Publication number
CN116755018A
CN116755018A CN202310057492.7A CN202310057492A CN116755018A CN 116755018 A CN116755018 A CN 116755018A CN 202310057492 A CN202310057492 A CN 202310057492A CN 116755018 A CN116755018 A CN 116755018A
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China
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current
primary winding
voltage
primary
measuring
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Inventor
李璿
尹晶
毛安澜
李辉
陈江波
吴士普
冯宇
汪本进
徐思恩
邱进
陈晓明
王玲
邵苠峰
杜砚
朱丝丝
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China Electric Power Research Institute Co Ltd CEPRI
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China Electric Power Research Institute Co Ltd CEPRI
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Priority to CN202310057492.7A priority Critical patent/CN116755018A/en
Publication of CN116755018A publication Critical patent/CN116755018A/en
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R35/00—Testing or calibrating of apparatus covered by the other groups of this subclass
    • G01R35/02—Testing or calibrating of apparatus covered by the other groups of this subclass of auxiliary devices, e.g. of instrument transformers according to prescribed transformation ratio, phase angle, or wattage rating
    • 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
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
    • G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
    • G01R27/26—Measuring inductance or capacitance; Measuring quality factor, e.g. by using the resonance method; Measuring loss factor; Measuring dielectric constants ; Measuring impedance or related variables
    • G01R27/2605—Measuring capacitance

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Measurement Of Resistance Or Impedance (AREA)

Abstract

The invention discloses a method and a system for measuring the distributed capacitance of a primary winding of an electromagnetic voltage transformer, wherein the method comprises the following steps: measuring exciting current of a secondary winding through a lock-in amplifier, and calculating the exciting current of the primary winding based on the transformation ratio of the primary current to the secondary current; after the primary voltage is reduced through a standard voltage transformer and a multi-disc induction voltage divider, converting the primary voltage into a voltage signal which does not exceed a preset voltage value, measuring the voltage signal through a phase-locked amplifier, and obtaining the earth current of the primary winding; calculating the capacitive leakage current of the primary winding based on the excitation current and the ground current of the primary winding; based on the capacitive leakage current of the primary winding, a distributed capacitance of the primary winding is calculated. The invention provides a method suitable for measuring the distributed capacitance of a primary winding of an electromagnetic voltage transformer, which is used for accurately measuring the distributed capacitance of the primary winding.

Description

Method and system for measuring distributed capacitance of primary winding of electromagnetic voltage transformer
Technical Field
The invention relates to the technical field of high-voltage electrical equipment, in particular to a method and a system for measuring the distributed capacitance of a primary winding of an electromagnetic voltage transformer.
Background
The electromagnetic voltage transformer is a common transformer in the power grid of China, primary voltage is converted into secondary voltage in proportion by utilizing an electromagnetic induction principle, and SF6 gas is used as a main insulating medium for the electromagnetic voltage transformer with high voltage class and is mainly used for GIS stations. The structure of the tank type electromagnetic voltage transformer is shown in fig. 1.
The iron core of the electromagnetic voltage transformer is formed by stacking silicon steel sheets, a secondary winding and a primary winding are sequentially wound on the iron core, a high-voltage shielding cover is added, a high-voltage lead is led out through a basin-type insulator, and the primary winding adopts a pagoda-type one-section trapezoid structure.
Compared with a power transformer, the electromagnetic voltage transformer has small load, and the primary winding current of the voltage transformer is generally in mu A level, so that the primary winding adopts small electromagnetic wire diameter, the turns of the internal winding are very dense, and the whole volume is smaller.
The size of the primary winding distributed capacitance of the electromagnetic voltage transformer has important significance for analyzing the frequency characteristic of the electromagnetic voltage transformer, but no effective method can accurately measure the primary winding distributed capacitance at present due to complex inter-turn capacitance and interlayer capacitance distribution.
Therefore, a technique is needed to achieve measurement of the primary winding distributed capacitance of an electromagnetic voltage transformer.
Disclosure of Invention
The technical scheme of the invention provides a method and a system for measuring the distributed capacitance of the primary winding of an electromagnetic voltage transformer, which are used for solving the problem of how to measure the distributed capacitance of the primary winding of the electromagnetic voltage transformer.
In order to solve the above problems, the present invention provides a method for measuring a distributed capacitance of a primary winding of an electromagnetic voltage transformer, the method comprising:
measuring exciting current of a secondary winding through a lock-in amplifier, and calculating the exciting current of the primary winding based on the transformation ratio of the primary current to the secondary current;
after the primary voltage is reduced through a standard voltage transformer and a multi-disc induction voltage divider, converting the primary voltage into a voltage signal which does not exceed a preset voltage value, measuring the voltage signal through a phase-locked amplifier, and obtaining the earth current of the primary winding;
calculating the capacitive leakage current of the primary winding based on the excitation current and the ground current of the primary winding;
based on the capacitive leakage current of the primary winding, a distributed capacitance of the primary winding is calculated.
Preferably, the measuring the exciting current of the secondary winding by the lock-in amplifier, calculating the exciting current of the primary winding based on the transformation ratio of the primary current to the secondary current, includes:
exciting current of secondary winding to be measuredDividing by the transformation ratio k to obtain the excitation current of the primary winding +.>
Preferably, the measuring the exciting current of the secondary winding by the lock-in amplifier includes:
the variable-frequency power supply is converted into a small voltage signal which does not exceed a predicted voltage value through a multi-disc induction voltage divider, and then the small voltage signal is input into the lock-in amplifier to be used as a reference signal;
after the exciting current of the secondary winding is converted into a voltage signal through a sampling resistor, the voltage signal is input into a measured end of the lock-in amplifier, and the amplitude and the phase of the exciting current of the secondary winding are obtained.
Preferably, the method further comprises: and measuring exciting currents of the secondary windings under different voltages by adjusting the voltage of the variable frequency source.
Preferably, the calculating the capacitive leakage current of the primary winding based on the excitation current and the ground current of the primary winding includes:
the capacitive leakage current of the primary winding is the difference between the ground current and the exciting current.
Based on another aspect of the present invention, the present invention provides a system for measuring distributed capacitance of a primary winding of an electromagnetic voltage transformer, the system comprising:
the first measuring unit is used for measuring exciting current of the secondary winding through the lock-in amplifier and calculating the exciting current of the primary winding based on the transformation ratio of the primary current and the secondary current;
the second measuring unit is used for converting the primary voltage into a voltage signal which does not exceed a preset voltage value after the primary voltage is reduced through the standard voltage transformer and the multi-disc induction voltage divider, measuring the voltage signal through the phase-locked amplifier, and obtaining the earth-entering current of the primary winding;
a first calculation unit configured to calculate a capacitive leakage current of a primary winding based on the excitation current and the ground current of the primary winding;
and a second calculation unit for calculating the distributed capacitance of the primary winding based on the capacitive leakage current of the primary winding.
Preferably, the first measuring unit is configured to measure an exciting current of the secondary winding through a lock-in amplifier, calculate the exciting current of the primary winding based on a transformation ratio of the primary current to the secondary current, and includes:
exciting current of secondary winding to be measuredDividing by the transformation ratio k to obtain the excitation current of the primary winding +.>。
Preferably, the first measuring unit is configured to measure an excitation current of the secondary winding through a lock-in amplifier, and includes:
the variable-frequency power supply is converted into a small voltage signal which does not exceed a predicted voltage value through a multi-disc induction voltage divider, and then the small voltage signal is input into the lock-in amplifier to be used as a reference signal;
after the exciting current of the secondary winding is converted into a voltage signal through a sampling resistor, the voltage signal is input into a measured end of the lock-in amplifier, and the amplitude and the phase of the exciting current of the secondary winding are obtained.
Preferably, the first measurement unit is further configured to: and measuring exciting currents of the secondary windings under different voltages by adjusting the voltage of the variable frequency source.
Preferably, the first calculating unit is configured to calculate a capacitive leakage current of a primary winding based on the excitation current and the ground current of the primary winding, and includes:
the capacitive leakage current of the primary winding is the difference between the ground current and the exciting current.
The technical scheme of the invention provides a method and a system for measuring the distributed capacitance of a primary winding of an electromagnetic voltage transformer, wherein the method comprises the following steps: measuring exciting current of a secondary winding through a lock-in amplifier, and calculating the exciting current of the primary winding based on the transformation ratio of the primary current to the secondary current; after the primary voltage is reduced through a standard voltage transformer and a multi-disc induction voltage divider, converting the primary voltage into a voltage signal which does not exceed a preset voltage value, measuring the voltage signal through a phase-locked amplifier, and obtaining the earth current of the primary winding; calculating the capacitive leakage current of the primary winding based on the excitation current and the ground current of the primary winding; based on the capacitive leakage current of the primary winding, the distributed capacitance of the primary winding is calculated. The invention provides a method for measuring the distributed capacitance of a primary winding of an electromagnetic voltage transformer by using the capacitive leakage current of the primary winding, wherein when voltage is applied to the primary winding, the earth current of the primary winding is the combined current of exciting current and the capacitive leakage circuit.
Drawings
Exemplary embodiments of the present invention may be more completely understood in consideration of the following drawings:
fig. 1 is a schematic structural view of an electromagnetic voltage transformer according to a preferred embodiment of the present invention;
FIG. 2 is a flow chart of a method for measuring distributed capacitance of primary windings of an electromagnetic voltage transformer in accordance with a preferred embodiment of the present invention;
FIG. 3 is a schematic diagram of an electromagnetic voltage transformer that accounts for capacitive leakage current in accordance with a preferred embodiment of the present invention;
FIG. 4 is a schematic diagram of an electromagnetic voltage transformer excitation characteristic measurement circuit according to a preferred embodiment of the present invention;
FIG. 5 is a schematic diagram of an electromagnetic voltage transformer primary winding ground current measurement loop according to a preferred embodiment of the present invention; and
fig. 6 is a system structural diagram for measuring the distributed capacitance of the primary winding of the electromagnetic voltage transformer according to the preferred embodiment of the present invention.
Detailed Description
The exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, however, the present invention may be embodied in many different forms and is not limited to the examples described herein, which are provided to fully and completely disclose the present invention and fully convey the scope of the invention to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the accompanying drawings is not intended to be limiting of the invention. In the drawings, like elements/components are referred to by like reference numerals.
Unless otherwise indicated, terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art. In addition, it will be understood that terms defined in commonly used dictionaries should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense.
Fig. 2 is a flowchart of a method for measuring distributed capacitance of a primary winding of an electromagnetic voltage transformer according to a preferred embodiment of the present invention. The invention provides a method for calculating the distributed capacitance of the primary winding of an electromagnetic voltage transformer by measuring the capacitive leakage current, which has the advantage of high accuracy. The accurate primary winding distributed capacitance is measured, and the method plays an important role in establishing a high-frequency equivalent circuit model of the electromagnetic voltage transformer and analyzing the high-frequency characteristics of the electromagnetic voltage transformer.
The invention analyzes the capacitive leakage current of the electromagnetic voltage transformer,
FIG. 3 is a graph of the consideration of capacitive leakage currentThe principle diagram of the electromagnetic voltage transformer is that a primary winding component is divided into n sections with equal turns, and the distributed capacitance of each section is C respectively 1 、C 2 、……、C n-1 、C n Excitation inductance is L m1 、L m2 、……、L mn-1 、L mn The capacitive leakage current of each segment is correspondingly +.> Exciting current isLet the total capacitive leakage current be +.>The total exciting current is +.>Then the primary current
As can be seen from the analysis of fig. 3, the primary winding current into the groundBy primary winding excitation current->And capacitive leakage current->Synthesis, i.e.)>As long as +.>And->The vector of the capacitive leakage current can be calculated.
As shown in fig. 2, the present invention provides a method for measuring a distributed capacitance of a primary winding of an electromagnetic voltage transformer, the method comprising:
step 101: measuring exciting current of a secondary winding through a lock-in amplifier, and calculating the exciting current of the primary winding based on the transformation ratio of the primary current to the secondary current;
preferably, measuring the exciting current of the secondary winding by the lock-in amplifier, calculating the exciting current of the primary winding based on the transformation ratio of the primary current to the secondary current, includes:
exciting current of secondary winding to be measuredDividing by the transformation ratio k to obtain the excitation current of the primary winding +.>
Preferably, measuring the exciting current of the secondary winding by the lock-in amplifier includes:
the variable frequency power supply is converted into a small voltage signal which does not exceed a predicted voltage value through a multi-disc induction voltage divider, and then the small voltage signal is input into a lock-in amplifier to be used as a reference signal;
after the exciting current of the secondary winding is converted into a voltage signal through a sampling resistor, the voltage signal is input into a measured end of the lock-in amplifier, and the amplitude and the phase of the exciting current of the secondary winding are obtained.
Preferably, the method further comprises: and measuring exciting currents of the secondary windings under different voltages by adjusting the voltage of the variable frequency source.
The primary winding exciting current of the inventionThe vector measurement method comprises the following steps:
in order to eliminate the interference of the capacitive leakage current of the primary winding, the primary winding exciting current is converted through a transformation ratio relation after the secondary winding exciting current is measured on the iron core wound with the secondary winding. The specific method comprises the following steps: 1) The secondary winding 1a1n can be applied with a frequencyModulated AC voltage U2, measuring exciting current passing through coil as secondary exciting currentSince the exciting current is typically a μa or mA level signal, it is difficult to accurately measure the minute signal with the conventional sensor excluding noise and interference signals. In order to solve the above-mentioned problems, the present invention proposes to use a Lock-in amplifier (LIA) to measure the micro signal with specific frequency. The phase-locked amplifier adopts the phase-sensitive detection technology to extract the signal amplitude and phase information which are the same as the reference frequency in the disordered waveform, and other signals or noise which are different from the reference frequency do not influence the measurement.
Because the input voltage of the lock-in amplifier cannot exceed 1V, the input voltage needs to be converted into small signal input with high precision, the invention proposes to adopt the multi-disc induction voltage divider to perform signal conversion, the accuracy level can reach 1 multiplied by 10 < -5 >, and the measurement requirement of excitation characteristics is met.
The measuring system based on the phase-locked amplifier mainly comprises the following parts: (1) the multi-disc induction voltage divider converts the variable frequency power supply into a small voltage signal, and inputs the small voltage signal into the lock-in amplifier as a reference signal; (2) the exciting current Im2 of the secondary winding is converted into a voltage signal through a sampling resistor and then is input into a tested end of the lock-in amplifier. The phase-locked amplifier can measure the amplitude and phase of the exciting current.
The invention measures the exciting current of the secondary windingDividing the ratio k to obtain the exciting current of the primary winding +.>
Step 102: after the primary voltage is reduced through a standard voltage transformer and a multi-disc induction voltage divider, converting the primary voltage into a voltage signal which does not exceed a preset voltage value, measuring the voltage signal through a phase-locked amplifier, and obtaining the earth current of the primary winding;
the pair of the inventionPrimary winding ground current vectorMeasurement:
primary winding earth currentThe measurement loop of (2) is shown in figure 5. The test was performed on a complete prototype of electromagnetic voltage transformer. After the primary voltage is reduced twice through a standard voltage transformer and a multi-disc induction voltage divider, the primary voltage is converted into a voltage signal below 1V, the voltage signal is input to a reference end of the phase-locked amplifier and is used as a reference signal, and after the primary exciting current is converted into the voltage signal through a sampling resistor, the voltage signal is input to a collection end of the phase-locked amplifier and is used as a signal to be tested. Different primary voltages are obtained by adjusting the voltage regulator, so that the primary winding ground current under different primary voltages is obtained>
Step 103: calculating the capacitive leakage current of the primary winding based on the excitation current and the ground current of the primary winding;
step 104: based on the capacitive leakage current of the primary winding, the distributed capacitance of the primary winding is calculated.
Preferably, calculating the capacitive leakage current of the primary winding based on the excitation current and the ground current of the primary winding includes:
the capacitive leakage current of the primary winding is the difference between the in-ground current and the exciting current.
The invention calculates the distributed capacitance:
according to vector calculation formula (1):
calculating to obtain the capacitive leakage current corresponding to the applied voltage UAccording to u=i C and/ωC, calculating to obtain the primary winding distributed capacitance C.
The invention provides a method suitable for measuring the primary winding distributed capacitance of an electromagnetic voltage transformer, which can accurately measure the primary winding distributed capacitance and has an important role in establishing an accurate circuit model of the electromagnetic voltage transformer and analyzing the high-frequency characteristic of the electromagnetic voltage transformer.
The following illustrates embodiments of the invention:
step one: the exciting current of the secondary winding of the electromagnetic voltage transformer is measured, referring to a measuring loop of fig. 4, on an iron core around which only the secondary winding is wound, the effective value and phase angle of the exciting current of the secondary winding are measured, and the exciting current of the primary winding is converted through a transformation ratio relation. The specific method comprises the following steps: 1) Applying an alternating voltage U2 with adjustable frequency and adjustable voltage to a secondary winding 1a1n of the electromagnetic voltage transformer through a variable frequency source, and connecting a standard resistor in series on a loop 1a1n for sampling loop current; 2) The U is converted into a small signal smaller than 1V through a multi-disc induction voltage divider and is input into a reference end (ref end) of the phase-locked amplifier; 3) The standard resistance can be 1 omega; 4) Reading the effective value and phase of the signal measured by the lock-in amplifier, i.e. loop exciting currentEffective value and phase of (a). 5) The measured exciting current +.>Effective value +.>Dividing the variable ratio k to obtain the effective value of the exciting current of the primary windingThe calculated primary winding exciting current phase is consistent with the measured secondary winding exciting current; 6) The secondary winding current values under different voltages can be obtained by adjusting the voltage of the variable frequency source.
Step two: primary winding ground current vectorMeasurement, see fig. 5. The test was performed on a complete prototype of electromagnetic voltage transformer. The frequency conversion source is connected with the voltage regulator and the step-up transformer in sequence, primary voltage with adjustable frequency and adjustable voltage is applied to the primary winding of the electromagnetic voltage transformer to be tested, and the effective value and the phase of exciting current of the primary winding are measured. The specific method comprises the following steps: 1) Connecting a standard voltage transformer with the same transformation ratio as an electromagnetic voltage transformer to the rear end of a step-up transformer, connecting a multi-disc induction voltage divider to a secondary winding of the standard voltage transformer, converting primary voltage into a voltage signal with the voltage below 1V, and inputting the voltage signal to a reference end (ref end) of a phase-locked amplifier to serve as a reference signal; 2) A standard resistor is connected in series on a primary winding loop as a sampling resistor, exciting current of the primary winding is converted into a voltage signal, and the voltage signal is input into a collection end of a phase-locked amplifier and used as a signal to be measured. The sampling resistor takes omega; 3) Different primary voltages are obtained by adjusting the voltage regulator, so that the primary winding ground current under different primary voltages is obtained>
Step three: and (5) calculating distributed capacitance. Calculated from vectorsCalculating to obtain the capacitive leakage current +.>According to u=i C and/ωC, calculating to obtain the primary winding distributed capacitance C.
Calculating and obtaining the distributed capacitance of the primary winding of the electromagnetic voltage transformer according to the relation between the capacitive leakage current of the primary winding and the applied voltage;
capacitive leakage current passing formula of primary winding of electromagnetic voltage transformerCalculated, wherein->Ground current for primary winding, < >>Exciting current for the primary winding;
primary winding exciting currentBy measuring the exciting current of the secondary winding>And according to->The obtained k is the transformation ratio of the electromagnetic voltage transformer;
secondary winding exciting current vectorThe method comprises the steps of measuring and obtaining through a phase locking method, applying voltage to a secondary winding 1a1n to excite the core under the condition that the transformer core only winds the secondary winding 1a1n, connecting sampling resistors in series in a measuring loop, converting exciting current of the core into a voltage signal, and inputting the voltage signal into a tested end of a phase locking amplifier to serve as a tested signal; the multi-disc induction voltage divider is utilized to reduce the applied voltage to a voltage signal below 1V, and the voltage signal is input into a reference end of the phase-locked amplifier and used as a reference signal; measuring the exciting current of the secondary winding by using a phase-locked amplifier>Effective value and phase of (a);
primary winding ground current vectorAlso obtained by measuring by phase-locked method, in complete electricPerforming a test on a magnetic voltage transformer prototype, applying voltage to a primary winding AN to excite AN iron core, connecting a sampling resistor in series in a measuring loop, converting the excitation current of the iron core into a voltage signal, and inputting the voltage signal to a tested end of a phase-locked amplifier to be used as a tested signal; the method comprises the steps that a standard voltage transformer and a multi-disc induction voltage divider are used for cascading, a voltage signal with the applied voltage reduced to below 1V is input into a reference end of a phase-locked amplifier and used as a reference signal; measuring the primary winding ground current by using a lock-in amplifier>Is effective and phase.
Fig. 6 is a system structural diagram for measuring the distributed capacitance of the primary winding of the electromagnetic voltage transformer according to the preferred embodiment of the present invention.
As shown in fig. 6, the present invention provides a system for measuring a distributed capacitance of a primary winding of an electromagnetic voltage transformer, the system comprising:
a first measurement unit 601, configured to measure an exciting current of the secondary winding through the lock-in amplifier, and calculate the exciting current of the primary winding based on a transformation ratio of the primary current to the secondary current;
preferably, the first measurement unit 601 is configured to measure an exciting current of the secondary winding through the lock-in amplifier, calculate the exciting current of the primary winding based on a transformation ratio of the primary current to the secondary current, and includes:
exciting current of secondary winding to be measuredDividing by the transformation ratio k to obtain the excitation current of the primary winding +.>
Preferably, the first measuring unit for measuring an exciting current of the secondary winding through the lock-in amplifier includes:
the variable frequency power supply is converted into a small voltage signal which does not exceed a predicted voltage value through a multi-disc induction voltage divider, and then the small voltage signal is input into a lock-in amplifier to be used as a reference signal;
after the exciting current of the secondary winding is converted into a voltage signal through a sampling resistor, the voltage signal is input into a measured end of the lock-in amplifier, and the amplitude and the phase of the exciting current of the secondary winding are obtained.
Preferably, the first measurement unit is further configured to: and measuring exciting currents of the secondary windings under different voltages by adjusting the voltage of the variable frequency source.
The second measurement unit 602 is configured to convert the primary voltage into a voltage signal not exceeding a preset voltage value after the primary voltage is reduced by using a standard voltage transformer and a multi-disc induction voltage divider, and measure the voltage signal by using a phase-locked amplifier to obtain an earth current of the primary winding;
a first calculation unit 603 for calculating a capacitive leakage current of the primary winding based on the excitation current and the ground current of the primary winding;
preferably, the first calculation unit for calculating the capacitive leakage current of the primary winding based on the excitation current and the ground current of the primary winding includes:
the capacitive leakage current of the primary winding is the difference between the in-ground current and the exciting current.
A second calculation unit 604 for calculating the distributed capacitance of the primary winding based on the capacitive leakage current of the primary winding.
The invention provides a system for measuring the distributed capacitance of the primary winding of an electromagnetic voltage transformer, which corresponds to the method for measuring the distributed capacitance of the primary winding of the electromagnetic voltage transformer, and is not described herein.
It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as a method, system, or computer program product. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein. The scheme in the embodiment of the invention can be realized by adopting various computer languages, such as object-oriented programming language Java, an transliteration script language JavaScript and the like.
The present invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. It is therefore intended that the following claims be interpreted as including the preferred embodiments and all such alterations and modifications as fall within the scope of the invention.
It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention also include such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.
The invention has been described with reference to a few embodiments. However, as is well known to those skilled in the art, other embodiments than the above disclosed invention are equally possible within the scope of the invention, as defined by the appended patent claims.
Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise therein. All references to "a/an/the [ means, component, etc. ]" are to be interpreted openly as referring to at least one instance of said means, component, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.

Claims (10)

1. A method of measuring distributed capacitance of a primary winding of an electromagnetic voltage transformer, the method comprising:
measuring exciting current of a secondary winding through a lock-in amplifier, and calculating the exciting current of the primary winding based on the transformation ratio of the primary current to the secondary current;
after the primary voltage is reduced through a standard voltage transformer and a multi-disc induction voltage divider, converting the primary voltage into a voltage signal which does not exceed a preset voltage value, measuring the voltage signal through a phase-locked amplifier, and obtaining the earth current of the primary winding;
calculating the capacitive leakage current of the primary winding based on the excitation current and the ground current of the primary winding;
based on the capacitive leakage current of the primary winding, a distributed capacitance of the primary winding is calculated.
2. The method of claim 1, the measuring the excitation current of the secondary winding by the lock-in amplifier, calculating the excitation current of the primary winding based on a transformation ratio of the primary current to the secondary current, comprising:
exciting current of secondary winding to be measuredDividing by the transformation ratio k to obtain the excitation current of the primary winding +.>
3. The method of claim 1, the measuring the excitation current of the secondary winding by a lock-in amplifier, comprising:
the variable-frequency power supply is converted into a small voltage signal which does not exceed a predicted voltage value through a multi-disc induction voltage divider, and then the small voltage signal is input into the lock-in amplifier to be used as a reference signal;
after the exciting current of the secondary winding is converted into a voltage signal through a sampling resistor, the voltage signal is input into a measured end of the lock-in amplifier, and the amplitude and the phase of the exciting current of the secondary winding are obtained.
4. The method of claim 1, further comprising: and measuring exciting currents of the secondary windings under different voltages by adjusting the voltage of the variable frequency source.
5. The method of claim 1, the calculating a capacitive leakage current of a primary winding based on the excitation current and the ground current of the primary winding, comprising:
the capacitive leakage current of the primary winding is the difference between the ground current and the exciting current.
6. A system for measuring distributed capacitance of a primary winding of an electromagnetic voltage transformer, the system comprising:
the first measuring unit is used for measuring exciting current of the secondary winding through the lock-in amplifier and calculating the exciting current of the primary winding based on the transformation ratio of the primary current and the secondary current;
the second measuring unit is used for converting the primary voltage into a voltage signal which does not exceed a preset voltage value after the primary voltage is reduced through the standard voltage transformer and the multi-disc induction voltage divider, measuring the voltage signal through the phase-locked amplifier, and obtaining the earth-entering current of the primary winding;
a first calculation unit configured to calculate a capacitive leakage current of a primary winding based on the excitation current and the ground current of the primary winding;
and a second calculation unit for calculating the distributed capacitance of the primary winding based on the capacitive leakage current of the primary winding.
7. The system of claim 6, the first measuring unit for measuring an exciting current of the secondary winding through the lock-in amplifier, calculating the exciting current of the primary winding based on a transformation ratio of the primary current to the secondary current, comprising:
exciting current of secondary winding to be measuredDividing by the transformation ratio k to obtain the excitation current of the primary winding +.>
8. The system of claim 6, the first measurement unit for measuring an excitation current of a secondary winding through a lock-in amplifier, comprising:
the variable-frequency power supply is converted into a small voltage signal which does not exceed a predicted voltage value through a multi-disc induction voltage divider, and then the small voltage signal is input into the lock-in amplifier to be used as a reference signal;
after the exciting current of the secondary winding is converted into a voltage signal through a sampling resistor, the voltage signal is input into a measured end of the lock-in amplifier, and the amplitude and the phase of the exciting current of the secondary winding are obtained.
9. The system of claim 6, the first measurement unit further to: and measuring exciting currents of the secondary windings under different voltages by adjusting the voltage of the variable frequency source.
10. The system of claim 6, the first calculation unit for calculating a capacitive leakage current of a primary winding based on the excitation current and the ground current of the primary winding, comprising:
the capacitive leakage current of the primary winding is the difference between the ground current and the exciting current.
CN202310057492.7A 2023-01-19 2023-01-19 Method and system for measuring distributed capacitance of primary winding of electromagnetic voltage transformer Pending CN116755018A (en)

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