CN210639238U

CN210639238U - Device for high-voltage capacitive monitoring by simultaneously measuring voltage and current

Info

Publication number: CN210639238U
Application number: CN201920879460.4U
Authority: CN
Inventors: 李密; 黄淦; 胡云; 陈杰; 张国军; 汤力
Original assignee: Shanghai Lingzhi Iot Network Co ltd
Current assignee: Shanghai Lingzhi Iot Network Co ltd
Priority date: 2019-06-12
Filing date: 2019-06-12
Publication date: 2020-05-29
Anticipated expiration: 2029-06-12

Abstract

The utility model relates to an equipment that carries out high pressure capacitive monitoring through simultaneous measurement voltage and electric current, including signal conditioning circuit, signal conditioning circuit connects the high-voltage potential transformer that reduces the high pressure on the capacitive equipment and export and the leakage current transformer of the end screen leakage current of output high pressure capacitive equipment, signal conditioning circuit carries out signal transmission through high-speed high resolution ADC and MCU control module. The capacitance of the capacitive equipment is calculated by adopting a structure of simultaneously measuring voltage and current signals of the equipment and accurately measuring the phase difference of the voltage and the current; the high-resolution ADC circuit with an ultrahigh sampling rate is adopted, so that the phase sampling precision is improved; and judging the phase of the signal by adopting a zero crossing point method.

Description

Device for high-voltage capacitive monitoring by simultaneously measuring voltage and current

Technical Field

The utility model relates to a capacitive equipment detection device field specifically is an equipment that carries out high-pressure capacitive monitoring through simultaneous measurement voltage and electric current.

Background

The conventional power equipment has insulation defects caused by factors such as poor manufacturing, aging and external force damage, so that insulation accidents can be caused, and the normal operation of a power grid is seriously influenced.

In order to prevent the occurrence of such major safety accidents, the conventional method adopted at present is to periodically cut off power to perform preventive tests and overhaul after the equipment is put into operation, so as to detect the insulation defects inside the equipment in time. However, the difference between the test condition of the power failure preventive test and the operation state is large, and the insulation condition of the power transformation equipment under the operation condition cannot be accurately diagnosed.

Along with the progress of automatic detection technology, the insulating on-line monitoring device of power equipment begins to obtain extensive application, for example chinese utility model patent CN109212446A discloses an insulating on-line monitoring device of substation equipment, including the device by one set of high voltage generator, the simulation produces the high pressure of field test, still has the standard test appearance of dielectric loss test and metallic oxide arrester resistive current test of one set of high accuracy grade for do the comparison test with the table of being examined. In addition, the system is provided with a dielectric loss and zinc oxide resistive current simulation device for simulating each dielectric loss and resistive current measurement point in the measurement range of the tested instrument.

However, the essence of the method still belongs to analog voltage or current for testing, and the method for testing single acquisition voltage or current cannot improve the precision of phase sampling, and is difficult to avoid the interference of high-frequency signals on zero-crossing points.

SUMMERY OF THE UTILITY MODEL

The utility model aims to solve the technical problem that an equipment and method for carrying out high-voltage capacitive monitoring through simultaneous measurement voltage and electric current are provided to solve the defect that exists among the prior art.

The utility model provides an above-mentioned technical problem's technical scheme as follows:

a device for carrying out high-voltage capacitive monitoring by simultaneously measuring voltage and current comprises a signal conditioning circuit, wherein the signal conditioning circuit is connected with a high-voltage transformer for reducing and outputting high voltage on capacitive equipment and a leakage current transformer for outputting end screen leakage current of the high-voltage capacitive equipment, and the signal conditioning circuit carries out signal transmission with an MCU control module through a high-speed high-resolution ADC (analog to digital converter);

furthermore, the signal conditioning circuit comprises a low-pass filter, an overvoltage protector and a signal amplifier which are sequentially connected, and conditions the input signal to the sampling range of the high-speed high-resolution ADC;

furthermore, the high-speed high-resolution ADC adopts 4MHz sampling frequency and 24-bit resolution, and can realize the phase measurement precision of +/-0.0045 degrees;

there is also provided a method for high voltage capacitive monitoring by simultaneously measuring voltage and current, comprising the steps of:

1) the high voltage on the capacitive equipment is reduced through a high-voltage transformer, the high voltage is output to a signal conditioning circuit in a sensing mode, and the end screen leakage current of the high-voltage capacitive equipment is output to the signal conditioning circuit in a sensing mode through a leakage current transformer;

2) the signal conditioning circuit conditions the input signal into the sampling range of the ADC;

3) the high-speed high-resolution ADC samples the input signal of the signal conditioning circuit by adopting a 4MHz sampling frequency; transmitting the sampling signal to the MCU control module;

4) the MCU control module performs low-pass filtering on the acquired voltage and current data to eliminate repeated zero crossing points;

5) the MCU control module calculates voltage signals and current signals to obtain respective average values, then obtains zero-crossing points t1 and t2 of the voltage and the current by comparing the average values with sine wave signals of respective input signals, further obtains phase difference △ t of the two signals, and then obtains capacitance and dielectric loss of the high-voltage capacitive equipment by calculation according to the phase difference;

6) and the MCU control module determines whether to give an alarm signal according to the calculated dielectric loss and the equipment parameters.

The utility model has the advantages that: the capacitance of the capacitive equipment is calculated by adopting a structure of simultaneously measuring voltage and current signals of the equipment and accurately measuring the phase difference of the voltage and the current; the high-resolution ADC circuit with an ultrahigh sampling rate is adopted, so that the phase sampling precision is improved; and judging the phase of the signal by adopting a zero crossing point method. By a software filtering method, the interference of high-frequency signals to zero crossing points is eliminated, and the purpose of accurately measuring the zero crossing points is achieved.

Drawings

FIG. 1 is a schematic structural view of the present invention;

FIG. 2 is a schematic view of the monitoring method of the present invention;

Detailed Description

The principles and features of the present invention are described below in conjunction with the following drawings, the examples given are only intended to illustrate the present invention and are not intended to limit the scope of the present invention.

As shown in fig. 1, an apparatus for performing high voltage capacitive monitoring by simultaneously measuring voltage and current includes a signal conditioning circuit, the signal conditioning circuit is connected to a high voltage transformer for reducing and outputting a high voltage on a capacitive apparatus and a leakage current transformer for outputting a leakage current at a final screen of the high voltage capacitive apparatus, and the signal conditioning circuit performs signal transmission with an MCU control module through a high-speed high-resolution ADC;

more specifically, the signal conditioning circuit comprises a low-pass filter, an overvoltage protector and a signal amplifier which are sequentially connected, and conditions an input signal to a sampling range of the high-speed high-resolution ADC;

more specifically, the high-speed high-resolution ADC adopts a 4MHz sampling frequency and a 24-bit resolution, and can realize a phase measurement accuracy of ± 0.0045 °;

in specific implementation, the device aims at the capacitive device, and can acquire the voltage and the leakage current of the capacitive device, calculate the phase difference between the voltage and the leakage current, obtain the capacitance and the dielectric loss of the capacitive device, and further analyze the insulation state of the capacitive device. If the insulation performance of the capacitive equipment is reduced, an alarm signal can be sent out.

The utility model also provides a method of carrying out high-pressure capacitive monitoring through simultaneous measurement voltage and electric current, including following step:

4) the MCU control module performs low-pass filtering on the acquired voltage and current data to eliminate repeated zero crossing points t 3;

5) as shown in fig. 2, the MCU control module calculates the voltage signal and the current signal to obtain respective average values, then compares the average values with the sine wave signals of the respective input signals to obtain zero-crossing points t1 and t2 of the voltage and the current, further obtain a phase difference △ t of the two signals, and then calculates the capacitance and the dielectric loss of the high voltage capacitive device according to the phase difference;

The above description is only for the preferred embodiment of the present invention, and is not intended to limit the present invention, and any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention should be included within the protection scope of the present invention.

Claims

1. An apparatus for high voltage capacitive monitoring by simultaneously measuring voltage and current, characterized by: the high-voltage capacitive device comprises a signal conditioning circuit, wherein the signal conditioning circuit is connected with a high-voltage transformer for reducing and outputting high voltage on the capacitive device and a leakage current transformer for outputting end screen leakage current of the high-voltage capacitive device, and the signal conditioning circuit is used for carrying out signal transmission through a high-speed high-resolution ADC and an MCU control module.

2. A device for capacitive monitoring of high voltages by simultaneous measurement of voltage and current according to claim 1, characterized in that: the signal conditioning circuit comprises a low-pass filter, an overvoltage protector and a signal amplifier which are sequentially connected, and conditions an input signal to a sampling range of the high-speed high-resolution ADC.

3. A device for capacitive monitoring of high voltages by simultaneous measurement of voltage and current according to claim 2, characterized in that: the high-speed high-resolution ADC adopts 4MHz sampling frequency and 24-bit resolution, and can realize the phase measurement precision of +/-0.0045 degrees.