A testing device and method for nanosecond pulse response time delay of metal oxide surge arrester

Abstract

This invention discloses a testing device and method for the nanosecond pulse response delay of a metal oxide surge arrester. The device mainly includes a nanosecond pulse generator, a high-voltage power divider, an absorption resistor, the surge arrester under test, and an oscilloscope. The overall structure is simple, the platform size is flexible, and the measurement location is unrestricted. The testing method can accurately obtain the surge arrester's response delay with a single pulse current, avoiding errors caused by multiple pulses generated by the nanosecond pulse generator. Furthermore, this method obtains the wave velocity and attenuation coefficient on the transmission line, and then solves simultaneous equations based on the current waveform measured at the measurement point to derive the nanosecond pulse waveform and the current waveform flowing through the surge arrester. The surge arrester's response delay is quantified using specific formulas, resulting in high-precision calculations and reliable test results.

Description

Technical Field

[0001] This invention belongs to the field of power system transient protection technology, specifically relating to a test device and method for the nanosecond pulse response delay of a metal oxide surge arrester. Background Technology

[0002] In power systems, surge arresters are indispensable overvoltage protection devices. When in a low-current region, they exhibit a high-resistance state. As the current flowing through the surge arrester increases, it transitions from a high-resistance state to a low-resistance state, discharging the current and thus protecting the power system. However, when a surge arrester encounters a pulse current with a leading-edge time on the order of nanoseconds, its conduction process may experience a certain time delay, rendering the arrester ineffective. Therefore, studying the response time delay of surge arresters under nanosecond pulses is of great significance. With the continuous development of power systems, the number of nanosecond-level impact disturbances that power systems may suffer is also increasing. Examples include very fast transient overvoltages (VFTOs) caused by the switching operations of disconnecting and grounding switches inside fully enclosed gas-insulated switchgear (GIS), and high-altitude electromagnetic pulses (HEMPs) generated by high-altitude nuclear explosions. These can all threaten the safe operation of the power system due to the response time delay of surge arresters.

[0003] However, existing research largely focuses on the response delay of low-voltage surge protectors under nanosecond pulses. For example, the IEC 61000-4-24 standard proposes a test method for testing the response delay of low-voltage surge protectors. However, this method requires two separate test operations; the nanosecond pulse generator will emit two pulses sequentially. Since the two output pulses cannot be exactly the same, this will lead to errors in the delay test results. For high-voltage surge protectors, the response delay testing lacks standardization, has low detection accuracy, and poor reliability. Summary of the Invention

[0004] The purpose of this invention is to overcome the above-mentioned shortcomings and provide a testing device and method for the nanosecond pulse response delay of metal oxide surge arresters. This device is mainly used for the accurate measurement of high voltage nanosecond pulse response delay. The device platform is flexible in size, simple in structure, and the measurement location is not limited. The test results are accurate and reliable.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A test device for the nanosecond pulse response delay of a metal oxide surge arrester includes a nanosecond pulse generator, one end of which is grounded, and the other end of which is connected to the first terminal of a high-voltage power divider.

[0007] The second terminal of the high-voltage power distributor is connected to one end of the surge arrester and one end of the load resistor R2, respectively. The other end of the surge arrester is grounded, and the other end of the load resistor R2 is grounded.

[0008] The third terminal of the high-voltage power divider is connected to one end of the load resistor R3, and the other end of the load resistor R3 is grounded.

[0009] The grounding terminals of the surge arrester, load resistor R2, and load resistor R3 are connected to the oscilloscope.

[0010] The high-voltage power distributor consists of three equal-value resistors connected in a star configuration, and the surge arrester is a metal oxide surge arrester.

[0011] One end of the nanosecond pulse generator is connected to the first terminal of the high-voltage power divider and one end of the load resistor R1, while the other end of the load resistor R1 is grounded.

[0012] The second terminal of the high-voltage power distributor 2, the transmission line L1, the transmission line L2 and the load resistor R2 are connected in series. One end of the surge arrester is connected between the transmission line L1 and the transmission line L2, and the other end is grounded.

[0013] The oscilloscope is connected to signal acquisition channels CH1, CH2, and CH3 respectively. Signal acquisition channel CH1 is set on the grounding wire of the surge arrester, signal acquisition channel CH2 is set on the grounding wire of the load resistor R2, and signal acquisition channel CH3 is set on the grounding wire of the load resistor R3.

[0014] A test method for a test device for the nanosecond pulse response delay of a metal oxide surge arrester includes the following steps:

[0015] Step 1: Debug and calibrate the experimental platform to obtain the wave velocity and attenuation coefficient on the transmission line;

[0016] Step 2: Use a nanosecond pulse generator to generate a pulse current and measure the current waveform at the arrester under test and at the end of the experimental platform to obtain the nanosecond pulse waveform and the current waveform flowing through the arrester. The accurate response delay of the arrester can be obtained by calculation.

[0017] That is, the resistance values ​​R of load resistors R1, R2, and R3, the impedance Z of the transmission line, and the resistance value r of the equivalent resistor of the high-voltage power divider satisfy the following formula:

[0018]

[0019] Where L0 and C0 are the inductance and capacitance per unit length of the transmission line, respectively; h p r0 is the height of the transmission line above ground; r0 is the radius of the transmission line; μ0 is the permeability of free space; μ0 is the magnetic permeability of free space. r ε is the relative permeability of the medium; ε0 is the vacuum permittivity; ε r is the relative permittivity of the medium.

[0020] In step 1: Repeat the measurement multiple times to calculate the average wave velocity and the average attenuation coefficient on the transmission line.

[0021] Step 2 specifically involves: based on the wave process of the nanosecond pulse current on the transmission line, the measured current waveform I can be written by solving a series of equations. CH1 I CH2 I CH3 With the surge arrester current I MOA The relationship between the pulse current I0 emitted by the nanosecond pulse generator:

[0022]

[0023] Where A, B, and C are the measurement attenuation coefficients of signal acquisition channels CH1, CH2, and CH3, respectively, and τ L The time it takes for a nanosecond pulse to propagate along the transmission line;

[0024] Solve for the measured current waveform I CH1 I CH2 I CH3 With the surge arrester current I MOA The system of equations consisting of the pulse current I0 emitted by the nanosecond pulse generator is solved to obtain:

[0025]

[0026] or

[0027]

[0028] Solve for I MOA After I0, the apparent origin of the current waveform is plotted at two reference points: 10% and 90% of the current peak value. The time difference between these two points is... According to the formula, the surge arrester response delay This allows us to obtain the precise response delay of the surge arrester under nanosecond pulses. By changing the output amplitude of the pulse generator, we can obtain the influence of the nanosecond pulse current amplitude on the surge arrester's response delay.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0030] This invention discloses a test device for the nanosecond pulse response delay of a metal oxide surge arrester. The device mainly includes a nanosecond pulse generator, a high-voltage power divider, an absorption resistor, the surge arrester under test, and an oscilloscope. The overall structure is simple, the device platform size is flexible, and the measurement location is not limited.

[0031] The high-voltage power divider of the present invention consists of three equal-value resistors connected in a star configuration. The resistance value of each resistor is one-third of the characteristic impedance of the transmission line, which can ensure that the pulse is equally distributed without reflection.

[0032] This method provides a test device for measuring the nanosecond pulse response delay of a metal oxide surge arrester. It can accurately obtain the arrester's response delay with a single pulse current, avoiding errors caused by multiple pulses generated by the nanosecond pulse generator. The method obtains the wave velocity and attenuation coefficient on the transmission line, and then solves simultaneous equations based on the measured current waveform at the measurement point to derive the nanosecond pulse waveform and the current waveform flowing through the arrester. The arrester's response delay is quantified using specific formulas, resulting in high-precision calculations and reliable test results.

[0033] The transmission line of this invention simulates the characteristic impedance of a real transmission conductor, ensuring the authenticity and reliability of the test results. The load resistance at the end matches the characteristic impedance of the transmission conductor, ensuring no signal reflection at the end of the line. In step 2, the average wave velocity and attenuation coefficient on the transmission line are repeatedly measured and calculated. In step 3, the response delay is solved by solving simultaneous equations for the three sets of data, further ensuring the accuracy of the calculation results. Finally, by changing the output amplitude of the pulse generator, the influence of the nanosecond pulse current amplitude on the surge arrester's response delay is obtained, further ensuring the reliability of the test results. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the experimental platform for measuring the response delay of a metal oxide surge arrester under a nanosecond pulse, as described in this invention.

[0035] Figure 2 To utilize Figure 1 The measured I CH1 I CH2 I CH3 Three current waveforms;

[0036] Figure 3 To utilize Figure 2 The solution obtained by I MOA The current waveforms of I0 and I0;

[0037] Figure 4 To utilize Figure 3 The solution yields the response delay of the gapless surge arrester under a nanosecond pulse, and also reveals the influence of the nanosecond pulse current amplitude variation on the surge arrester's response delay.

[0038] Among them, 1-nanosecond pulse generator, 2-high voltage power distributor, 3-surge arrester, and 4-oscilloscope. Detailed Implementation

[0039] The following is in conjunction with the appendix Figure 1-4 The present invention will be further described below.

[0040] See Figure 1 A test device for the nanosecond pulse response delay of a metal oxide surge arrester includes a nanosecond pulse generator 1, one end of which is grounded and the other end of which is connected to the first terminal of a high-voltage power divider 2.

[0041] The second terminal of the high-voltage power distributor 2 is connected to one end of the surge arrester 3 and one end of the load resistor R2 respectively. The other end of the surge arrester 3 is grounded, and the other end of the load resistor R2 is grounded.

[0042] The third terminal of the high-voltage power divider 2 is connected to one end of the load resistor R3, and the other end of the load resistor R3 is grounded.

[0043] The grounding terminals of surge arrester 3, load resistor R2, and load resistor R3 are respectively connected to oscilloscope 4.

[0044] The high-voltage power distributor 2 consists of three equal-value resistors connected in a star configuration, and the surge arrester 3 is a metal oxide surge arrester.

[0045] Preferably, the three equivalent resistors of the high-voltage power divider 2 are r1, r2 and r3, with the other end of r1 being the first terminal, the other end of r2 being the second terminal, and the other end of r3 being the third terminal.

[0046] The wire between the nanosecond pulse generator 1 and the high-voltage power divider 2 is connected to one end of the load resistor R1, and the other end of the load resistor R1 is grounded.

[0047] The second terminal of the high-voltage power distributor 2, the transmission line L1, the transmission line L2 and the load resistor R2 are connected in series. One end of the surge arrester 3 is connected between the transmission line L1 and the transmission line L2, and the other end is grounded.

[0048] The oscilloscope 4 is connected to signal acquisition channels CHI, CH2, and CH3 respectively. Signal acquisition channel CHI is set on the grounding wire of surge arrester 3, signal acquisition channel CH2 is set on the grounding wire of load resistor R2, and signal acquisition channel CH3 is set on the grounding wire of load resistor R3.

[0049] A test method for a test device for the nanosecond pulse response delay of a metal oxide surge arrester includes the following steps:

[0050] Step 1: Debug and calibrate the experimental platform to obtain the wave velocity and attenuation coefficient on the transmission line. During the setup of the experimental platform, the transmission conductor is installed to simulate the characteristic impedance of a real overhead line, ensuring the reliability of the test results. The high-voltage power divider consists of three equal-value resistors connected in a star configuration, with a resistance value one-third of the characteristic impedance of the transmission conductor, ensuring equal distribution of the pulse without reflection. The load at the end of the line has the same characteristic impedance as the transmission conductor, ensuring no signal reflection at the end of the line. That is, the resistance values ​​R of load resistors R1, R2, and R3, the impedance Z of the transmission conductor, and the resistance r of the equal-value resistor of the high-voltage power divider 2 satisfy the following formula to ensure impedance matching in the experimental circuit, eliminating wave reflection in the circuit:

[0051]

[0052] Where L0 and C0 are the inductance and capacitance per unit length of the transmission line, respectively; h p r0 is the height of the transmission line above ground; r0 is the radius of the transmission line; μ0 is the vacuum permeability (4π×102). -7 H / m); μ r ε0 is the relative permeability of the medium, which can be taken as 1 for both transmission wires and cables; ε0 is the vacuum permittivity (1 / (36π)×102). -9 F / m); ε r is the relative permittivity of the medium.

[0053] Step 2: Debug and calibrate the experimental platform, repeat the measurement multiple times, and calculate the average wave velocity and average attenuation coefficient on the transmission line;

[0054] Step 3: Use a nanosecond pulse generator to generate a pulse current with a leading edge time of 20ns and a pulse width of 530ns, respectively at... Figure 1 The measured current waveforms at three signal acquisition channels CH1, CH2, and CH3 are as follows: Figure 2 As shown;

[0055] Step 4: Based on the wave process of the nanosecond pulse current on the transmission line, the following equations can be written simultaneously:

[0056]

[0057] Where A, B, and C are the measurement attenuation coefficients of signal acquisition channels CH1, CH2, and CH3, respectively, and τ L This is the time it takes for a nanosecond pulse to propagate along the transmission line;

[0058] Solve for the measured current waveform I CH1 I CH2 I CH3 With the surge arrester current I MOAThe system of equations consisting of the pulse current I0 emitted by the nanosecond pulse generator can be solved to obtain...

[0059]

[0060] or

[0061]

[0062] Step 5: Solve for I MOA After I0, such as Figure 3 As shown, the apparent origins O1 and O2 of the current waveform are plotted using two reference points, 10% and 90% of the current peak value. The time difference between these two points is...

[0063] Step 6: Based on the formula, determine the surge arrester response time. This allows us to obtain a relatively accurate response delay result for the surge arrester under a nanosecond pulse, such as... Figure 4 As shown.

[0064] Step 7: By changing the output amplitude of the pulse generator, the influence of the nanosecond pulse current amplitude on the surge arrester response delay can be obtained, such as... Figure 4 As shown.

[0065] Preferred embodiment:

[0066] A composite-jacketed metal oxide surge arrester of model YH5WZ-17 / 45 was selected as the experimental test sample, and the following setup was constructed: Figure 1 The experimental platform shown was debugged and calibrated, and the wave velocity and attenuation coefficient on the transmission line were obtained as 2.76 × 10⁻⁶. 8 m / s and 0.995 / m. A nanosecond pulse generator was used to generate a pulse current with a leading edge time of 20 ns, a pulse width of 530 ns, and an amplitude of approximately 650 A. These pulses were applied at... Figure 1 The current waveforms measured at three signal acquisition channels, CH1, CH2, and CH3, are as follows: Figure 2 As shown. Based on the wave process of nanosecond pulse current on the transmission line, the following equations can be written simultaneously:

[0067]

[0068] Where A, B, and C are the measurement attenuation coefficients of signal acquisition channels CH1, CH2, and CH3, respectively, and τ L This is the time it takes for a nanosecond pulse to propagate along the transmission line;

[0069] Solve for the measured current waveform I CH1 I CH2 I CH3 With the surge arrester current IMOA The system of equations consisting of the pulse current I0 emitted by the nanosecond pulse generator can be solved to obtain...

[0070]

[0071] Solving for I from the above formula MOA After obtaining the I0 waveform, the apparent origin of the current waveform is plotted at two reference points: 10% and 90% of the current peak value. The time difference between these two points is the current waveform. like Figure 3 As shown. According to the formula, the surge arrester response delay... This yields a relatively accurate response delay result for the surge arrester under a nanosecond pulse, Δt = 0.79 ns.

[0072] By changing the output amplitude of the pulse generator, the influence of the nanosecond pulse current amplitude on the surge arrester's response delay can be obtained, such as... Figure 4 As shown, under a pulse current impact with a leading edge time of 20ns, a pulse width of 530ns, and an amplitude range of 600A to 5000A, the surge arrester response delay is 2ns ± 2ns.

[0073] In summary, the above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A test method for a test device for the nanosecond pulse response delay of a metal oxide surge arrester, characterized in that, The testing device includes a nanosecond pulse generator (1), one end of which is grounded and the other end of which is connected to the first terminal of the high-voltage power divider (2). The second terminal of the high voltage power distributor (2) is connected to one end of the surge arrester (3) and one end of the load resistor R2 respectively. The other end of the surge arrester (3) is grounded, and the other end of the load resistor R2 is grounded. The third terminal of the high-voltage power divider (2) is connected to one end of the load resistor R2, and the other end of the load resistor R2 is grounded; The grounding terminals of the surge arrester (3), the load resistor R2, and the load resistor R3 are respectively connected to the oscilloscope (4); The testing method includes the following steps: Step 1: Debug and calibrate the experimental platform to obtain the wave velocity and attenuation coefficient on the transmission line; Step 2: Use a nanosecond pulse generator to generate a pulse current and measure the current waveform at the surge arrester under test and at the end of the experimental platform. Obtain the nanosecond pulse waveform and the current waveform flowing through the surge arrester. Calculate the surge arrester's response time delay. Specifically: Based on the wave process of the nanosecond pulse current on the transmission line, the measured current waveform I can be written by solving simultaneous equations. CH1 I CH2 I CH3 With the surge arrester current I MOA The relationship between the pulse current I0 emitted by the nanosecond pulse generator: Where A, B, and C are the measurement attenuation coefficients of signal acquisition channels CH1, CH2, and CH3, respectively. L This is the time it takes for a nanosecond pulse to propagate along the transmission line; Solve for the measured current waveform I CH1 I CH2 I CH3 With the surge arrester current I MOA The system of equations consisting of the pulse current I0 emitted by the nanosecond pulse generator is solved to obtain: or Solve for I MOA After I0, the apparent origin of the current waveform is plotted at two reference points: 10% and 90% of the current peak value. The time difference between these two points is... According to the formula, the surge arrester response delay The response delay of the surge arrester under a nanosecond pulse can be obtained. By changing the output amplitude of the pulse generator, the influence of the amplitude of the nanosecond pulse current on the response delay of the surge arrester can be obtained.

2. The test method for the test device of the nanosecond pulse response delay of a metal oxide surge arrester as described in claim 1, characterized in that, The high-voltage power distributor (2) is composed of three equal-value resistors connected in a star configuration, and the surge arrester (3) is a metal oxide surge arrester.

3. The test method for the test device of nanosecond pulse response delay of a metal oxide surge arrester as described in claim 1, characterized in that, One end of the nanosecond pulse generator (1) is connected to the first terminal of the high voltage power distributor (2) and one end of the load resistor R1, and the other end of the load resistor R1 is grounded.

4. The test method for the test device of nanosecond pulse response delay of a metal oxide surge arrester as described in claim 1, characterized in that, The high-voltage power distributor (2) has its second terminal, transmission line L1, transmission line L2 and load resistor R3 connected in series. One end of the surge arrester (3) is connected between transmission line L1 and transmission line L2, and the other end is grounded.

5. The test method for the test device of nanosecond pulse response delay of a metal oxide surge arrester as described in claim 1, characterized in that, The oscilloscope (4) is connected to signal acquisition channels CH1, CH2 and CH3 respectively. Signal acquisition channel CH1 is set on the grounding wire of the surge arrester (3), signal acquisition channel CH2 is set on the grounding wire of the load resistor R3 and signal acquisition channel CH3 is set on the grounding wire of the load resistor R2.

6. The test method for the test device of nanosecond pulse response delay of a metal oxide surge arrester according to claim 1, characterized in that, The resistance values ​​R of the load resistors R1, R2, and R3, the impedance Z of the transmission line, and the resistance value r of the equivalent resistor of the high-voltage power divider (2) satisfy the following formula: Where L0 and C0 are the inductance and capacitance per unit length of the transmission line, respectively; h p r0 is the height of the transmission line above ground; r0 is the radius of the transmission line; μ0 is the permeability of free space; μ0 is the magnetic permeability of free space. r ε is the relative permeability of the medium; ε0 is the vacuum permittivity; ε r is the relative permittivity of the medium.

7. The test method for the test device of nanosecond pulse response delay of a metal oxide surge arrester according to claim 1, characterized in that, In step 1: Repeat the measurement multiple times to calculate the average wave velocity and the average attenuation coefficient on the transmission line.

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