Partial discharge synchronous calibration device and method based on combined high-frequency current sensor

Abstract

The invention discloses a partial discharge synchronous calibration device and method based on a combined high-frequency current sensor, and the method comprises the steps: respectively measuring the time shift of a low-frequency-band high-frequency current sensor and the time shift of a high-frequency-band high-frequency current sensor through a synchronous calibration device, and obtaining the time difference between the low-frequency-band high-frequency current sensor and the high-frequency-band high-frequency current sensor. Two output channels of the signal generator are respectively connected with the input of the radio frequency current probe calibration device and the input of the digital oscilloscope channel 1, the output of the radio frequency current probe calibration device is connected with the non-inductive resistor, and the output of the low-frequency-band high-frequency current sensor and the output of the high-frequency-band high-frequency current sensor are respectively connected with the input of the digital oscilloscope channel 2 in sequence. According to the method, the time shift of the low-frequency-band high-frequency current sensor and the time shift of the high-frequency-band high-frequency current sensor are obtained, the time difference of measuring the same partial discharge signal by the two types of high-frequency current sensors is eliminated, and technical support is provided for realizing cable partial discharge accurate positioning based on the combined type high-frequency current sensor.

Description

Technical Field

[0001] The invention relates to the field of insulation state detection of high-voltage cable lines, and in particular to a partial discharge synchronous calibration device and method based on a combined high-frequency current sensor. Background Art

[0002] As the power system develops in the direction of high voltage and large capacity, it is increasingly important to ensure the safe operation of power equipment, and the impact and losses caused by power outages on the national economy and people's lives are increasing. With the continuous development of the economy, urban power infrastructure has continued to develop rapidly in recent years. High-voltage transmission cable lines are safe, reliable, space-saving and beautify the city. They meet the development requirements of urbanization and modernization and are increasingly adopted. However, due to the tightly wrapped structure of high-voltage cables, it is very difficult to accurately understand and grasp the insulation status of the main insulation of high-voltage cables. In particular, potential insulation defects inside high-voltage cables are difficult to accurately detect and locate, and the accuracy and effectiveness of detection methods and means are slightly insufficient. In order to ensure the reliability of power supply, it is particularly important to detect the operating conditions and health of newly built and laid cables.

[0003] Partial discharge is the main manifestation of latent defects in high-voltage cable lines. It is not only the main cause of insulation aging, but also the main characteristic parameter reflecting the insulation state. The factory test of the high-voltage cable body needs to be tested for partial discharge. On the other hand, the handover test after the high-voltage cable is laid also needs to be tested for variable frequency resonance synchronous partial discharge. Finally, during the service period of the high-voltage cable, in order to clarify the healthy insulation state of the high-voltage cable line, the high-voltage cable operation and maintenance department must also regularly conduct partial discharge live detection tests on the high-voltage cable line. These tests can accurately discover the partial discharge phenomenon in the high-voltage cable line, which is an intuitive, ideal and effective test method for diagnosing the insulation state of the high-voltage cable line. However, since the combined high-frequency current sensor is composed of a low-frequency high-frequency current sensor and a high-frequency current sensor, and the phase-frequency characteristics of these two types of high-frequency current sensors are different, the time shifts generated by these two types of high-frequency current sensors when measuring the same partial discharge pulse are different, and there is a time difference, which will cause positioning errors when using the cable partial discharge detection system based on the combined high-frequency current sensor to locate the partial discharge of the high-voltage cable line. Therefore, it is necessary to propose a partial discharge synchronous calibration device and method based on a combined high-frequency current sensor to eliminate the time difference between the two types of high-frequency current sensors in measuring the same partial discharge signal, and provide technical support for the precise positioning of cable partial discharge based on a combined high-frequency current sensor. Summary of the invention

[0004] The present invention provides a partial discharge synchronous calibration device and method based on a combined high-frequency current sensor, which can solve the problem of influence of the time difference of the combined high-frequency current sensor on the precise positioning of partial discharge.

[0005] The device of the present invention comprises a signal generator, a radio frequency current probe calibration device, and a digital oscilloscope. The output of the signal generator is divided into two channels, which are respectively connected to the input of the radio frequency current probe calibration device and the input of channel 1 of the digital oscilloscope. The output of the radio frequency current probe calibration device is connected to a non-inductive resistor, and the input has a characteristic impedance of 50 ohms. The output of the low-frequency band high-frequency current sensor and the output of the high-frequency band high-frequency current sensor are respectively connected to the input of channel 2 of the digital oscilloscope in sequence.

[0006] A partial discharge synchronous calibration device and method based on a combined high-frequency current sensor has the following specific steps:

[0007] 1) Pass the low-frequency high-frequency current sensor through the central conductor of the RF current probe calibration device, that is, correctly install the low-frequency high-frequency current sensor in the RF current probe calibration device;

[0008] 2) Divide the signal generator output into two channels and connect them to the input of the RF current probe calibration device and the input of channel 1 of the digital oscilloscope respectively;

[0009] 3) Connect the low-band high-frequency current sensor output to the digital oscilloscope channel 2 input;

[0010] 4) Set the signal generator to output a sinusoidal voltage with a frequency of 1 MHz and an amplitude of no less than 1 V, and turn on the signal generator output;

[0011] 5) Read the phase difference between channel 2 and channel 1 of the digital oscilloscope

[0012] 6) Use formula (1) to calculate the time shift T of the low-frequency high-frequency current sensor L ;

[0013]

[0014] In the formula, The unit is angle, T L The unit is μs;

[0015] 7) Turn off the signal generator output, remove the low-frequency band high-frequency current sensor from the RF current probe calibration device, and disconnect the low-frequency band high-frequency current sensor output from the digital oscilloscope channel 2 input;

[0016] 8) Pass the high-frequency current sensor through the central conductor of the radio frequency current probe calibration device, that is, correctly install the high-frequency current sensor in the radio frequency current probe calibration device;

[0017] 9) Connect the high-frequency current sensor output of the high-frequency band to the input of channel 2 of the digital oscilloscope;

[0018] 10) Set the signal generator to output a sinusoidal voltage with a frequency of 50 MHz and an amplitude of no less than 1 V, and turn on the signal generator 11 output;

[0019] 11) Read the phase difference between channel 2 and channel 1 of the digital oscilloscope

[0020] 12) Use formula (2) to calculate the time shift T of the high-frequency current sensor in the high-frequency band: H ;

[0021]

[0022] In the formula, The unit is angle, T H The unit is μs;

[0023] 13) Turn off the signal generator output, remove the high-frequency current sensor from the RF current probe calibration device, disconnect the signal generator output and the RF current probe calibration device input, and disconnect the high-frequency current sensor output and the digital oscilloscope channel 2 input.

[0024] Through the above steps, the time shift T of the low-frequency high-frequency current sensor is obtained. L and the time shift T of the high frequency current sensor in the high frequency band H , the time difference T between the low-frequency band high-frequency current sensor and the high-frequency band high-frequency current sensor is calculated using formula (3).

[0025] T=T L -T H (3)

[0026] Wherein, the unit of T is μs.

[0027] The technical effects of the present invention are as follows:

[0028] The technical solution of the present invention is used to obtain the time shift of the low-frequency band high-frequency current sensor and the time shift of the high-frequency current sensor in the high-frequency band, eliminating the time difference between the two types of high-frequency current sensors in measuring the same partial discharge signal, providing technical support for the precise positioning of cable partial discharge based on the combined high-frequency current sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the principle of the present invention;

[0030] 11 is a signal generator, 12 is a radio frequency current probe calibration device, 15 is a digital oscilloscope, 13 is a low frequency band high frequency current sensor, and 14 is a high frequency band high frequency current sensor. DETAILED DESCRIPTION

[0031] The present invention provides a partial discharge synchronous calibration device and method based on a combined high-frequency current sensor, which is used to measure the time shift of a low-frequency band high-frequency current sensor and a high-frequency band high-frequency current sensor, thereby obtaining the time difference between the low-frequency band high-frequency current sensor and the high-frequency band high-frequency current sensor:

[0032] The present invention is based on a partial discharge synchronous calibration device based on a combined high-frequency current sensor, which is composed of a signal generator, a radio frequency current probe calibration device, and a digital oscilloscope. On this basis, a partial discharge synchronous calibration device and method based on a combined high-frequency current sensor are proposed. The synchronous calibration device is used to measure the time shift of the low-frequency band high-frequency current sensor and the time shift of the high-frequency band high-frequency current sensor respectively, and then the time difference between the low-frequency band high-frequency current sensor and the high-frequency band high-frequency current sensor is obtained. In the positioning algorithm of the cable partial discharge detection system based on the combined high-frequency current sensor, the time difference between the two types of high-frequency current sensors measuring the same partial discharge signal can be easily eliminated.

[0033] The specific steps are as follows:

[0034] Pass the low-frequency band high-frequency current sensor 13 through the central conductor of the radio frequency current probe calibration device 12, that is, correctly install the low-frequency band high-frequency current sensor 13 in the radio frequency current probe calibration device 12;

[0035] The output of the signal generator 11 is divided into two channels and connected to the input of the radio frequency current probe calibration device 12 and the input of the channel 1 of the digital oscilloscope 15 respectively;

[0036] Connect the output of the low-band high-frequency current sensor 13 to the input of channel 2 of the digital oscilloscope 15;

[0037] Set the signal generator 11 to output a sinusoidal voltage with a frequency of 1 MHz and an amplitude of no less than 1 V, and turn on the output of the signal generator 11;

[0038] Read the phase difference between channel 2 and channel 1 of the digital oscilloscope 15

[0039] The time shift T of the low-frequency high-frequency current sensor 13 is calculated using formula (1): L ;

[0040]

[0041] In the formula, The unit is angle, T LThe unit is μs;

[0042] Turn off the output of the signal generator 11, take out the low-frequency band high-frequency current sensor 13 from the radio frequency current probe calibration device 12, and disconnect the output of the low-frequency band high-frequency current sensor 13 from the input of channel 2 of the digital oscilloscope 15;

[0043] Pass the high-frequency band high-frequency current sensor 14 through the central conductor of the radio frequency current probe calibration device 12, that is, correctly install the high-frequency band high-frequency current sensor 14 in the radio frequency current probe calibration device 12;

[0044] Connect the output of the high-frequency current sensor 14 in the high-frequency band to the input of channel 2 of the digital oscilloscope 15;

[0045] Set the signal generator 11 to output a sinusoidal voltage with a frequency of 50 MHz and an amplitude of no less than 1 V, and turn on the output of the signal generator 11;

[0046] Read the phase difference between channel 2 and channel 1 of the digital oscilloscope 15

[0047] The time shift T of the high-frequency current sensor 14 in the high-frequency band is calculated using formula (2): H ;

[0048]

[0049] In the formula, The unit is angle, T H The unit is μs;

[0050] Turn off the output of the signal generator 11, take out the high-frequency band high-frequency current sensor 14 from the RF current probe calibration device 12, disconnect the output of the signal generator 11 and the input of the RF current probe calibration device 12, and disconnect the output of the high-frequency band high-frequency current sensor 14 and the input of channel 2 of the digital oscilloscope 15.

[0051] It can be seen that the partial discharge synchronous calibration device and method based on the combined high-frequency current sensor of the present invention measures the time shift of the low-frequency band high-frequency current sensor and the high-frequency band high-frequency current sensor, and then obtains the time difference between the low-frequency band high-frequency current sensor and the high-frequency band high-frequency current sensor, thereby providing technical support for realizing the precise positioning of cable partial discharge based on the combined high-frequency current sensor, and has important engineering practical value.

Claims

1. A synchronous partial discharge calibration device based on a combined high-frequency current sensor, characterized in that: It includes a signal generator, a radio frequency current probe calibration device, and a digital oscilloscope. The output of the signal generator is divided into two channels, which are respectively connected to the input of the radio frequency current probe calibration device and the input of channel 1 of the digital oscilloscope. The output of the radio frequency current probe calibration device is connected to a non-inductive resistor, and the output of the low-frequency band high-frequency current sensor and the output of the high-frequency band high-frequency current sensor are respectively connected to the input of channel 2 of the digital oscilloscope.

2. The PD synchronous calibration device based on the combined high-frequency current sensor according to claim 1 is characterized in that: The signal generator outputs a sinusoidal voltage signal, the lowest sinusoidal voltage frequency is not higher than 10kHz, the highest sinusoidal voltage frequency is not lower than 100MHz, the sinusoidal voltage amplitude is not lower than 1V, and the output impedance is 50 ohms.

3. The PD synchronous calibration device based on the combined high-frequency current sensor according to claim 1 is characterized in that: The output of the RF current probe calibration device is connected to a 50-ohm non-inductive resistor with a 20mm diameter center conductor. The power of the 50-ohm non-inductive resistor is not less than 2W. Its frequency range is from DC to 1000MHz, and the standing wave ratio is not higher than 1.

5.

4. The PD synchronous calibration device based on the combined high-frequency current sensor according to claim 1 is characterized in that: The output of the low-band high-frequency current sensor is connected to the input of channel 2 of the digital oscilloscope. The low-frequency cutoff frequency is 100kHz, the high-frequency cutoff frequency is 3MHz, the transmission impedance is not less than 10mV / mA, and the output impedance is 50 ohms.

5. The PD synchronous calibration device based on the combined high-frequency current sensor according to claim 1, characterized in that: The high-frequency current sensor output in the high-frequency band is connected to the input of channel 2 of the digital oscilloscope. Its low-frequency cutoff frequency is 3MHz, its high-frequency cutoff frequency is 100MHz, the transmission impedance is not less than 5mV / mA, and the output impedance is 50 ohms.

6. The PD synchronous calibration device based on the combined high-frequency current sensor according to claim 1, characterized in that: The channel 1 input of the digital oscilloscope is connected to the output of the signal generator, and the channel 2 input is connected to the outputs of the low-frequency band high-frequency current sensor and the high-frequency band high-frequency current sensor in sequence. The analog bandwidth is not less than 200 MHz, and the sampling rate is not less than 2 GHz.

7. The synchronous calibration device for cable partial discharge detection system based on combined high-frequency current sensor according to claim 6 is characterized in that: The number of channels is not less than two, the record length is not less than 1M, and it has the function of measuring the phase shift of sinusoidal signals.

8. A method for synchronous calibration of partial discharge based on a combined high-frequency current sensor, characterized in that: The synchronous calibration device is used to measure the time shift of the low-frequency band high-frequency current sensor and the time shift of the high-frequency band high-frequency current sensor respectively, so as to obtain the time difference between the low-frequency band high-frequency current sensor and the high-frequency band high-frequency current sensor.

9. The method according to claim 8, characterized in that The specific steps are as follows: 1) Pass the low-frequency high-frequency current sensor through the central conductor of the RF current probe calibration device, that is, correctly install the low-frequency high-frequency current sensor in the RF current probe calibration device; 2) Divide the signal generator output into two channels and connect them to the input of the RF current probe calibration device and the input of channel 1 of the digital oscilloscope respectively; 3) Connect the low-band high-frequency current sensor output to the digital oscilloscope channel 2 input; 4) Set the signal generator to output a sinusoidal voltage with a frequency of 1 MHz and an amplitude of no less than 1 V, and turn on the signal generator output; 5) Read the phase difference between channel 2 and channel 1 of the digital oscilloscope 6) Use formula (1) to calculate the time shift T of the low-frequency high-frequency current sensor L ; In the formula, The unit is angle, T L The unit is μs; 7) Turn off the signal generator output, remove the low-frequency band high-frequency current sensor from the RF current probe calibration device, and disconnect the low-frequency band high-frequency current sensor output from the digital oscilloscope channel 2 input; 8) Pass the high-frequency current sensor through the central conductor of the radio frequency current probe calibration device, that is, correctly install the high-frequency current sensor in the radio frequency current probe calibration device; 9) Connect the high-frequency current sensor output of the high-frequency band to the input of channel 2 of the digital oscilloscope; 10) Set the signal generator to output a sinusoidal voltage with a frequency of 50 MHz and an amplitude of no less than 1 V, and turn on the signal generator output; 11) Read the phase difference between channel 2 and channel 1 of the digital oscilloscope 12) Use formula (2) to calculate the time shift T of the high-frequency current sensor in the high-frequency band: H ; In the formula, The unit is angle, T H The unit is μs; 13) Turn off the signal generator output, take out the high-frequency current sensor from the RF current probe calibration device, disconnect the signal generator output and the RF current probe calibration device input, and disconnect the high-frequency current sensor output and the digital oscilloscope channel 2 input; Through the above steps, the time shift T of the low-frequency high-frequency current sensor is obtained. L and the time shift T of the high frequency current sensor in the high frequency band H , the time difference T between the low-frequency band high-frequency current sensor and the high-frequency band high-frequency current sensor is calculated using formula (3); T=T L -T H (3) Wherein, the unit of T is μs.

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