CN-116643092-B - Device, system, method and application for measuring capacitance

CN116643092BCN 116643092 BCN116643092 BCN 116643092BCN-116643092-B

Abstract

The invention discloses a device, a system, a method and application for measuring capacitance, relating to the technical field of measuring electric variables; the device comprises a shell, a first electrode, a second electrode and an insulating supporting leg, wherein the electrodes are used for being connected with a tester, a vent hole is formed in the shell, the method comprises the steps of obtaining the capacitance of a stray capacitance of a second flange of a capacitive voltage transformer to the ground before operation, obtaining the capacitance of a capacitance measuring device before operation according to a positive wiring method, obtaining the capacitance of the capacitance measuring device during initial detection, taking the capacitance of the capacitance measuring device as a reference, and comparing and calculating to obtain the capacitance of the stray capacitance during initial detection.

Inventors

LIU XIAOFEI
JIA XIAOYU
MA YALI
Yang Kainan
LI QIANG
GAO YAN
ZHAO JINING
YANG SHIBO
HU WEITAO
ZENG YULIAN
LI LIANZHONG

Assignees

国网河北省电力有限公司超高压分公司
国家电网有限公司

Dates

Publication Date: 20260505
Application Date: 20230601

Claims (7)

1. A method for measuring capacitance is characterized in that based on a device for measuring capacitance, the device for measuring capacitance comprises a shell, a first electrode, a second electrode and an insulating support leg, wherein the shell is used for insulation, the insulating support leg is connected with the shell, the insulating support leg is used for supporting the shell, the first electrode is arranged on one side of the shell and is used for being connected with a high-voltage output line of a tester, the second electrode is arranged on the other side of the shell and is used for being connected with a signal acquisition line of the tester, and the first electrode and the second electrode form capacitance of the capacitance measuring device The measuring step comprises obtaining the stray capacitance of the second flange of the capacitor voltage transformer CVT to the ground before operation Capacitance of (2) Measuring and obtaining the capacitance of the capacitance measuring device before operation according to the positive wiring method Capacitance of (2) Capacitance of capacitance measuring device when first detection is obtained according to positive wiring method measurement Capacitance of (2) The capacitance of the capacitance measuring device As a reference, stray capacitance at the time of first detection is obtained by contrast calculation Capacitance of (2) Eliminating stray capacitance To obtain the upper power-saving capacity of the capacitor voltage transformer CVT during the first detection Capacitance of (2) In the latter test after the equipment is put into operation, the first power failure detection after the CVT is electrified is used as the first detection, and in the measuring step, the capacitance before the capacitance measuring device is put into operation is measured And capacitance at first check Stray capacitance before operation Capacitance of (2) Substituting (11), calculating to obtain stray capacitance in initial inspection Capacitance of (2) ; In the formula (11), the amino acid sequence of the compound, Stray capacitance to ground of second flange of capacitive voltage transformer CVT at first detection Is used for the control of the capacitance of the capacitor, Stray capacitance to ground for the second flange of the pre-commissioning capacitive voltage transformer CVT Is used for the control of the capacitance of the capacitor, For measuring the capacitance of the device for measuring stray capacitance before operation Is used for the control of the capacitance of the capacitor, Capacitance of first-check stray capacitance measuring device Is not required.
2. A method for measuring capacitance as in claim 1 wherein the housing is a cube.
3. A method for measuring capacitance as defined in claim 1 wherein in the measuring step, the upper power saving capacity of the capacitive voltage transformer CVT before commissioning is obtained based on a positive wire measurement Initial capacitance of (2) Measurement based on reverse wiring shielding method to obtain upper section total capacitance of capacitor voltage transformer CVT before operation Initial capacitance of (2) Substituting (1), and calculating to obtain stray capacitance of the second flange of the capacitor voltage transformer CVT to ground before operation Initial capacitance of (2) ; In the formula (1), the components are as follows, Stray capacitance to ground for the second flange of the pre-commissioning capacitive voltage transformer CVT Is used for the control of the capacitance of the capacitor, Upper power-saving capacitor for capacitor voltage transformer CVT before operation Stray capacitance to ground with second flange Total capacitance in parallel Is used for the control of the capacitance of the capacitor, Upper power-saving capacitor for capacitor voltage transformer CVT before operation Is not required.
4. A method for measuring capacitance according to claim 1, wherein in the measuring step, the upper total capacitance of the capacitor voltage transformer CVT at the time of initial detection is measured based on a reverse wiring shielding method Is not less than a total capacitance of (2) Substituting (2) to calculate and obtain upper power-saving capacity of capacitor voltage transformer CVT in initial detection Capacitance of (2) ; In the formula (2), the amino acid sequence of the compound, Upper power-saving capacitor of capacitor voltage transformer CVT during initial detection Is used for the control of the capacitance of the capacitor, The upper section total capacitance of the capacitive voltage transformer CVT in the first detection Is used for the control of the capacitance of the capacitor, Stray capacitance to ground of second flange of capacitive voltage transformer CVT at first detection Is not required.
5. A system for measuring capacitance comprising a tester for measuring capacitance, a device for measuring capacitance and a measuring module for obtaining stray capacitance of a second flange of a capacitive voltage transformer CVT to ground before commissioning, for a method for measuring capacitance as claimed in claim 1 Capacitance of (2) Obtaining the capacitance of the capacitance measuring device before operation Capacitance of (2) Obtaining the capacitance of the capacitance measuring device at the time of the first inspection Capacitance of (2) In the later test after the equipment is put into operation, the first power failure detection after the CVT is electrified is taken as the first detection, and the stray capacitance at the first detection is obtained by calculation according to the formula (11) Capacitance of (2) ; In the formula (11), the amino acid sequence of the compound, Stray capacitance to ground of second flange of capacitive voltage transformer CVT at first detection Is used for the control of the capacitance of the capacitor, Stray capacitance to ground for the second flange of the pre-commissioning capacitive voltage transformer CVT Is used for the control of the capacitance of the capacitor, For measuring the capacitance of the device for measuring stray capacitance before operation Is used for the control of the capacitance of the capacitor, Capacitance of first-check stray capacitance measuring device Is not required.
6. The system for measuring capacitance as in claim 5 wherein the measurement module is further configured to obtain a total upper capacitance of the capacitive voltage transformer CVT at the time of the initial test Is not less than a total capacitance of (2) The upper power-saving capacitor of the capacitor voltage transformer CVT at the time of initial detection is obtained through calculation according to the formula (2) Capacitance of (2) ; In the formula (2), the amino acid sequence of the compound, Upper power-saving capacitor of capacitor voltage transformer CVT during initial detection Is used for the control of the capacitance of the capacitor, The upper section total capacitance of the capacitive voltage transformer CVT in the first detection Is used for the control of the capacitance of the capacitor, Stray capacitance to ground of second flange of capacitive voltage transformer CVT at first detection Is not required.
7. A computer-readable storage medium, in which a computer program is stored, characterized in that the computer program, when being executed by a processor, implements the steps of a method for measuring capacitance as claimed in claim 1, 3 or 4.

Description

Device, system, method and application for measuring capacitance Technical Field The invention relates to the technical field of measuring electric variables, in particular to a device, a system, a method and application for measuring electric capacity. Background The writer searches for the formula TACD_ALL (CVT AND upper node AND capacitance) as follows, obtaining a closer prior art solution. Application publication number CN111239671a, entitled a method for measuring capacitance and dielectric loss of coupling capacitance of upper section of CVT. The upper section coupling capacitance and the middle section coupling capacitance are considered to be pure capacitors, and the upper section coupling capacitance and the middle section coupling capacitance can be adopted to measure in parallel, so that the total capacitance and the total dielectric loss value of a capacitance parallel structure are measured by a variable frequency dielectric loss tester in a reverse wiring method, then the capacitance and the dielectric loss value of the middle section coupling capacitance are measured independently by a positive wiring method, and finally the capacitance and the dielectric loss value of the upper section coupling capacitance are calculated by a theoretical formula based on an electrical relation under the condition of the capacitance and the dielectric loss value of the known middle section coupling capacitance, thereby ensuring scientific accuracy and rigor, and greatly reducing equipment maintenance cost and power production cost compared with the existing dismantling method. The application publication number is CN109901096A, and the name is an online monitoring system and method for the metering precision of a capacitive voltage transformer. Including synchronous acquisition card, voltage transformer, capacitive voltage transformer and electromagnetic type voltage transformer primary side all are connected to high-voltage bus, and the secondary side all is connected to voltage transformer through the secondary cable, and two voltage transformers are connected to synchronous acquisition card, still are connected with ambient temperature measurement module, ambient humidity measurement module and leakage current measurement module on the synchronous acquisition card. The electromagnetic voltage transformer is used as a standard PT and the capacitive voltage transformer to respectively and simultaneously collect voltage signals, the signal of the standard PT is used as a standard, the operation condition of the CVT is judged by calculating the ratio difference (amplitude and phase) between the signal obtained by the CVT and the standard signal, if the error exceeds the set allowable range, the CVT is required to be overhauled or replaced in time, and the problem of the CVT is solved. The authorized bulletin number is CN103063931B, the name is 500kV CVT multiple dielectric loss test system and test method thereof. The vehicle-mounted dielectric loss tester comprises a transformer, wherein the transformer is provided with two output windings, one end of the first output winding is connected with a relay in series, the other end of the first output winding is grounded, one end of the second output winding of the transformer is grounded, and the other end of the second output winding of the transformer is connected to the capacitor voltage transformer through a high-voltage vacuum relay. The measurement process of the test system is automatic, one-time wiring and one-key operation is performed, all test items of 500kVCVT are completed, and the test time is effectively reduced. Through effectual function integration, reduce the volume, reduce wiring number of times, improve work efficiency, reduce intensity of labour, the time shortens 2/3, and two passageways are exported to the instrument, accomplish two capacitance measurement simultaneously. In combination with the above three patent documents and prior art schemes, the inventors analyzed the prior art schemes as follows. Capacitive voltage transformers CVT, CAPACITANCE TYPE voltage transformer, which in power systems function to measure voltage for meters, protection devices, can also couple carrier frequencies to transmission lines for long distance communications, remote measurements, selective line high frequency protection, etc. Reverse wiring is typically used to measure the dielectric loss and capacitance of the CVT after the CVT is put into operation. The reverse wiring collects signals from the high voltage output line, and the stray capacitance influence of the huge metal flange on other grounding parts usually causes the problems of section dielectric loss and inaccurate capacitance test on the CVT. Problems and considerations in the prior art: How to solve the technical problem that the capacitance of the stray capacitance can not be obtained. Disclosure of Invention The invention provides a device, a system, a method and application for measuring