Optimization method of parallel protection gap of lightning protection and ice protection insulators

Abstract

The invention discloses a method for optimizing the parallel protection gap of lightning protection and ice protection insulators, the steps of which are: 1) obtaining a volt-ampere characteristic curve; 2) obtaining a functional relationship between a resistor voltage and a current; 3) calculating the through-current energy w of the arrester; 4) determining the maximum absorption energy W of the resistor under a large impulse withstand current 0 ; 5) Establish the electromagnetic transient model of the transmission line without lightning arrester and the simulation model of lightning protection and ice protection insulator; 6) Get the arrester with current energy W 0 The lightning current amplitude I flowing through the lightning protection section model 1 ; 7) According to the volt-ampere characteristic curve, determine the lightning current amplitude I 1 The corresponding maximum residual voltage value of the arrester is U 1 8) The parallel protection gap distance is obtained from the relationship between the flashover voltage and the gap distance. The present invention optimizes the parallel protection gap of the lightning protection and ice protection insulator, and ensures that the zinc oxide resistor in the lightning protection section is not damaged when a large lightning energy passes through it through the coordination between the lightning arrester and the parallel gap.

Description

Technical Field

[0001] The invention relates to the technical field of lightning protection devices for power overhead lines, and in particular to a method for optimizing parallel protection gaps of lightning and ice protection insulators. Background Art

[0002] With the development of my country's power grid in recent years, the coverage area of ​​transmission lines has become wider and wider, which has also led to many transmission lines passing through some hilly areas with complex terrain and cold climate. In particular, in the south, affected by factors such as meteorology and terrain, transmission lines are prone to icing. Due to the thermal effect of the absence of current in lightning arresters, icing is more serious than that of conductors, and line break accidents are prone to occur in the case of heavy icing. After the lightning arrester breaks, it falls on the conductor, causing the line to trip and cause the line to stop operating, seriously affecting the normal power supply of users. However, the current treatment of ice flashover and lightning flashover problems has the defect of single function, which can only prevent ice or lightning. Summary of the invention

[0003] The object of the present invention is to provide a method for optimizing the parallel protection gap of lightning protection and ice protection insulators, comprising the following steps:

[0004] 1) Obtain the volt-ampere characteristic curve of the zinc oxide resistor in the lightning protection and ice protection composite insulator arrester section and the 4 / 10μs impulse withstand current of the arrester. The amplitude of the impulse withstand current is recorded as I0.

[0005] The steps to obtain the arrester volt-ampere characteristic data include:

[0006] 1.1) Apply impulse current to the arrester alone and measure the residual voltage of the zinc oxide resistor under the current.

[0007] 1.2) Change the impulse current amplitude and return to step 1.1) until the residual voltage of the zinc oxide resistor under different impulse currents is measured, and a volt-ampere characteristic curve is established based on the impulse current amplitude and the residual voltage.

[0008] 2) Perform function fitting on the volt-ampere characteristic data of the zinc oxide resistor to obtain the functional relationship between the resistor voltage and current.

[0009] The functional relationship between the voltage and current of the zinc oxide resistor is as follows:

[0010] u=Ci a (1)

[0011] Where C and a are constants obtained by function fitting.

[0012] Among them, the 4 / 10μs impulse current i with an amplitude of I0 is a function of time t, that is:

[0013]

[0014] In the formula, a, b, c, d are constants obtained by function fitting. Constant b = I0 / 4, u is the residual voltage of the arrester. I0 is the current amplitude.

[0015] 3) Calculate the current energy w of the lightning arrester.

[0016] The maximum energy withstand capability w of the arrester is as follows:

[0017] w=∫uidt (3)

[0018] In the formula, u and i represent the residual voltage and current of the arrester respectively. t is time. According to the functional relationship between the voltage and current of the zinc oxide resistor and the volt-ampere characteristic data of the resistor, the maximum absorbed energy W0 of the resistor under the impulse withstand high current can be determined.

[0019] 4) Establish the electromagnetic transient model of the transmission line without lightning protection wire and the simulation model of lightning protection and anti-icing insulator in the ATP simulation software.

[0020] 5) Inject lightning current into the simulation model, change the lightning current amplitude, and obtain the lightning current amplitude I1 flowing through the lightning protection section when the arrester has a current energy of W0.

[0021] 6) According to the volt-ampere characteristic curve, determine the maximum residual voltage value U1 of the lightning arrester corresponding to the lightning current amplitude I1.

[0022] 7) Taking the residual voltage value U1 as the reference point, the breakdown voltage test of the parallel protection gap is carried out to obtain the relationship between the flashover voltage and the gap distance.

[0023] The method for the breakdown voltage test of the parallel protection gap includes: an impulse voltage generator outputs a pulse voltage to the parallel protection gap structure in the lightning protection and ice protection insulator, performs a flashover voltage test, measures a relationship curve between the impulse flashover voltage and the gap distance, and then obtains the parallel protection gap distance. The parallel protection gap distance increases a margin ΔD.

[0024] The relationship between flashover voltage and gap distance is shown below:

[0025] u'=MD+N (4)

[0026] Where u' is the flashover voltage, D is the gap distance, and M and N are constants obtained by fitting.

[0027] The technical effect of the present invention is unquestionable. Aiming at the structure of the existing lightning protection and ice protection composite insulator, the present invention optimizes the distance of the parallel protection gap of the lightning arrester section. Compared with other ordinary insulators, the lightning protection and ice protection insulator of the present invention adds a parallel protection gap in the lightning arrester section, and optimizes the design from the perspective of the maximum energy tolerance of the lightning arrester, so as to realize the protection of the zinc oxide resistor in the lightning protection section of the lightning protection and ice protection insulator and ensure its normal operation.

[0028] The present invention can not only make the arrester absorb the impact energy to the maximum extent and pass the lightning current within the safe range, but also effectively protect the zinc oxide valve plate of the arrester from being damaged by the high-amplitude lightning current, thereby ensuring the normal operation of the composite insulator. After determining the parallel protection gap distance, the present invention can obtain the corresponding relationship between the current carrying capacity of the lightning protection and ice protection composite insulator and the lightning tripping rate.

[0029] The present invention optimizes the parallel protection gap of the lightning protection and ice protection insulator, and ensures that the zinc oxide resistor of the lightning protection section is not damaged when a large lightning energy passes through it through the mutual cooperation of the lightning arrester and the parallel gap. When the through-current energy is low, the lightning energy passing through the lightning arrester is absorbed by the zinc oxide resistor, and the parallel gap will not break down. When the through-current energy of the lightning protection section exceeds the maximum energy tolerance of the lightning arrester, the lightning current generates a high residual voltage at both ends of the lightning protection section, and the parallel gap breaks down to protect the lightning arrester. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a model of composite insulator for lightning protection and ice protection. DETAILED DESCRIPTION

[0031] The present invention is further described below in conjunction with the embodiments, but it should not be understood that the above subject matter of the present invention is limited to the following embodiments. Without departing from the above technical ideas of the present invention, various substitutions and changes are made according to the common technical knowledge and customary means in the art, which should all be included in the protection scope of the present invention.

[0032] Embodiment 1:

[0033] See also Figure 1 , a method for optimizing the parallel protection gap of lightning protection and ice protection insulators, specifically comprising the following steps:

[0034] 1) Obtain the volt-ampere characteristic curve of the zinc oxide resistor in the lightning protection and ice protection composite insulator arrester section and the 4 / 10μs impulse withstand current of the arrester. The amplitude of the impulse withstand current is recorded as I0.

[0035] The steps to obtain the arrester volt-ampere characteristic data include:

[0036] 1.1) Apply impulse current to the arrester alone and measure the residual voltage of the zinc oxide resistor under the current.

[0037] 1.2) Change the impulse current amplitude and return to step 1.1) until the residual voltage of the zinc oxide resistor under different impulse currents is measured, and a volt-ampere characteristic curve is established based on the impulse current amplitude and the residual voltage.

[0038] 2) Perform function fitting on the volt-ampere characteristic data of the zinc oxide resistor to obtain the functional relationship between the resistor voltage and current.

[0039] The functional relationship between the voltage and current of the zinc oxide resistor is as follows:

[0040] u=Ci a (1)

[0041] Where C and a are constants obtained by function fitting.

[0042] Among them, the 4 / 10μs impulse current i with an amplitude of I0 is a function of time t, that is:

[0043]

[0044] In the formula, a, b, c, d are constants obtained by function fitting. Constant b = I0 / 4, u is the residual voltage of the arrester. I0 is the current amplitude.

[0045] 3) Calculate the maximum current energy w of the lightning arrester.

[0046] The maximum energy withstand capability w of the arrester is as follows:

[0047] w=∫uidt (3)

[0048] In the formula, u and i represent the residual voltage and current of the arrester respectively. t is the time. The maximum absorbed energy of the zinc oxide resistor under the impulse withstand high current can be determined by the above formula and recorded as W0.

[0049] 4) Establish an electromagnetic transient simulation model for the groundless transmission line. The lightning current is selected from the standard lightning wave, and the wave head and wave tail are 2.6 / 50μs.

[0050] 5) Establish a simulation model including the lightning protection section and insulation section of the lightning protection and ice protection insulator.

[0051] The lightning protection section includes a zinc oxide resistor and a pair of hardware. The pair of hardware is two bent metal spherical electrodes located at both ends of the lightning protection section. The two spherical electrodes form a parallel protection gap of the lightning protection section. The function of the protection gap is to protect the valve plate of the lightning arrester from being damaged when a large lightning energy passes through the arrester and the parallel gap.

[0052] 6) Inject the lightning current into the simulation model, and according to the energy equivalence principle, simulate and calculate the lightning current amplitude I1 flowing through the lightning protection section model when the arrester has a current waveform of 2.6 / 50μs and the current energy is W0.

[0053] 7) According to the volt-ampere characteristic curve, determine the maximum residual voltage value U1 of the lightning arrester corresponding to the lightning current amplitude I1.

[0054] 8) Taking the residual voltage value U1 as the reference point, a breakdown voltage test of the parallel protection gap is carried out to obtain the relationship between the flashover voltage and the gap distance.

[0055] The method for the breakdown voltage test of the parallel protection gap includes: an impulse voltage generator outputs a pulse voltage to the parallel protection gap structure in the lightning protection and ice protection insulator, performs a flashover voltage test, measures a relationship curve between the impulse flashover voltage and the gap distance, and then obtains the parallel protection gap distance. The parallel protection gap distance increases a margin ΔD.

[0056] The relationship between flashover voltage and gap distance is shown below:

[0057] u'=MD+N (4)

[0058] Where u' is the flashover voltage, D is the gap distance, and M and N are constants obtained by fitting.

[0059] 9) Optimize the gap distance to obtain the optimized distance of the parallel protection gap.

[0060] The method for optimizing the gap distance includes: adding a margin ΔD to the gap distance.

[0061] The present invention allows the line to be operated without a lightning arrester. At the same time, in order to improve the lightning resistance performance of the transmission line without a lightning arrester, the line insulator is replaced with an ice-flash-proof synthetic insulator with a lightning protection function. Figure 1 The insulator can protect against both lightning and ice flash, and should be easy to install without changing the original structure of the tower, thus saving equipment selection and grid construction expenses. Operation experience shows that lightning and ice protection insulators can improve the lightning resistance performance of transmission lines without lightning arresters.

[0062] Embodiment 2:

[0063] See also Figure 1 , a method for optimizing the parallel protection gap of lightning protection and ice protection insulators, specifically comprising the following steps:

[0064] 1) Ensure the effective protection of lightning protection and ice protection insulators for transmission lines without lightning protection wires. At the same time, based on economic considerations, the maximum current carrying capacity of lightning protection and ice protection insulators is set according to the lightning protection requirements of lines with different voltage levels, that is, the 4 / 10μs large current impulse tolerance of the lightning arrester in the lightning protection section is set to 100kA, 150kA, 175kA, 200kA, etc.

[0065] 2) Acquisition of arrester volt-ampere characteristic data: Apply impulse current to the arrester selected in step 1 alone, change the impulse current amplitude, measure the residual voltage of the zinc oxide resistor under different currents, and obtain the volt-ampere characteristic curve of the zinc oxide resistor of the arrester.

[0066] 3) Perform function fitting on the arrester volt-ampere characteristic curve obtained in step 2 to obtain the functional relationship between the voltage and current of the zinc oxide resistor, which is expressed as: u = Ci a ; At the same time, the waveform of the 4 / 10μs large current with an amplitude of I0 is simplified to a function of time t:

[0067]

[0068] In the above formula: abcd is the constant obtained by function fitting, where b=I0 / 4, and u is the residual voltage of the lightning arrester.

[0069] 4) Based on the volt-second characteristic curve obtained in step 3 and the fitting function of the 4 / 10μs large current, calculate the energy absorption w of the zinc oxide resistor of the arrester when the impulse current passes through it. The calculation formula is:

[0070] w=∫uidt

[0071] Considering that the μs-level discharge time can be ignored compared with the heat dissipation time constant of the surrounding materials, the heat dissipation effect is ignored in the calculation of absorbed energy, and the discharge process is considered to be an adiabatic process. Combining the impulse current waveform function and the volt-ampere characteristic curve, the maximum absorbed energy W0 of the zinc oxide resistor under the 4 / 10μs impulse current with an amplitude of I0 is obtained.

[0072] 5) Based on the maximum current energy W0 of the lightning arrester obtained in step 4 without damaging the zinc oxide resistor. In the simulation software, an electromagnetic transient simulation model of the groundless transmission line is established, and the volt-ampere characteristic data of the lightning arrester are used to establish the simulation model of the lightning protection section and the insulation section of the lightning protection and anti-icing insulator. The lightning current selects the standard lightning wave, and the wave head and wave tail are 2.6 / 50μs. When lightning strikes the connection between the lightning protection and anti-icing insulator and the conductor, the lightning current is the largest. According to the energy equivalence principle, the lightning current amplitude I1 corresponding to the lightning current flowing through the lightning protection section model when the current energy of the lightning arrester is W0 under the 2.6 / 50μs current waveform is simulated and calculated, and then the maximum residual voltage value U1 of the lightning arrester is calculated using the lightning arrester volt-ampere characteristic curve of step 2.

[0073] 6) Take the voltage U1 obtained in step 5 as the reference point to carry out the breakdown voltage test of the parallel protection gap. The parallel protection gap structure in the lightning protection and ice protection insulator is a rod-rod structure. The impulse voltage generator outputs the pulse voltage, and the flashover voltage test is carried out to measure the relationship curve between the impulse flashover voltage and the gap distance.

[0074] The step 6 specifically includes: since the positive polarity flashover voltage is relatively low, a positive polarity impulse voltage of 2.6 / 50 μs is applied to the rod-rod gap structure, and relevant data of the flashover voltage under positive polarity varying with the rod-rod gap distance are obtained, and a relationship curve between the positive polarity impulse flashover voltage and the gap distance is obtained by fitting:

[0075] u'=MD+N

[0076] In the above formula: u' is the flashover voltage, D is the gap distance, and M and N are constants obtained by fitting.

[0077] 7) Optimize the protection gap distance, and calculate the distance of the parallel protection gap of the lightning protection section according to the relationship curve between the positive polarity impulse flashover voltage and the gap distance obtained from the lightning impulse flashover test results and the residual voltage value U1 in step 5. At the same time, in order to achieve complete protection of the lightning arrester, a certain margin ΔD can be allowed for the parallel gap distance according to the lightning protection requirements, thereby determining the final parallel protection gap distance.

Claims

1. A method for optimizing the parallel protection gap of lightning protection and ice protection insulators, characterized in that: The following steps are involved: 1) Obtain the volt-ampere characteristic curve of the zinc oxide resistor in the lightning protection and ice protection composite insulator arrester section and the impulse withstand large current of the arrester; the amplitude of the impulse withstand large current is recorded as I0; 2) Perform function fitting on the resistor volt-ampere characteristic data to obtain the functional relationship between the voltage and current of the zinc oxide resistor; 3) Calculate the arrester's through-current energy w; 4) According to the functional relationship between the voltage and current of the zinc oxide resistor, determine the maximum absorbed energy W0 of the resistor under the impulse withstand high current; 5) Establish the electromagnetic transient model of the transmission line without lightning protection wire and the simulation model of lightning protection and ice protection insulator; 6) Injecting lightning current into the simulation model, changing the lightning current amplitude, and obtaining the lightning current amplitude I1 flowing through the lightning protection section when the arrester current energy is W0; 7) According to the volt-ampere characteristic curve of the zinc oxide resistor, determine the maximum residual voltage value U1 of the lightning arrester corresponding to the lightning current amplitude I1; 8) Taking the residual voltage value U1 as the reference point, a breakdown voltage test of the parallel protection gap is carried out to obtain the relationship between the flashover voltage and the gap distance, and then the parallel protection gap distance is obtained.

2. The method for optimizing the parallel protection gap of lightning protection and ice protection insulators according to claim 1 is characterized in that: The current is a 4 / 10μs impulse withstand large current.

3. The method for optimizing the parallel protection gap of lightning protection and ice protection insulators according to claim 1 is characterized in that: The maximum energy withstand capability w of the arrester is as follows: w=∫uidt (1) Where, u and i represent the residual voltage and current of the arrester respectively; t is the time.

4. The method for optimizing the parallel protection gap of lightning protection and ice protection insulators according to claim 1, characterized in that: The steps to obtain the arrester volt-ampere characteristic data include: 1) Apply impulse current to the arrester alone and measure the residual voltage of the resistor under the current; 2) Change the impulse current amplitude and return to step 1) until the residual voltage of the resistor under different impulse currents is measured, and a volt-ampere characteristic curve is established based on the impulse current amplitude and the residual voltage.

5. The method for optimizing the parallel protection gap of lightning protection and ice protection insulators according to claim 1, characterized in that: The functional relationship between the resistor voltage and current is shown below: u=Ci a (2) In the formula, C and a are constants obtained by function fitting; Among them, the 4 / 10μs impulse current i with an amplitude of I0 is a function of time t, that is: Where a, b, c, d are constants obtained by function fitting; constant b = I0 / 4, u is the residual voltage of the arrester; I0 is the current amplitude.

6. The method for optimizing the parallel protection gap of lightning protection and ice protection insulators according to claim 1, characterized in that: The method for the breakdown voltage test of the parallel protection gap includes: an impulse voltage generator outputs a pulse voltage to the parallel protection gap structure in the lightning protection and ice protection insulator, performs a flashover voltage test, and measures a relationship curve between the impulse flashover voltage and the gap distance.

7. The method for optimizing the parallel protection gap of lightning protection and ice protection insulators according to claim 1, characterized in that: The relationship between flashover voltage and gap distance is shown below: u'=MD+N (4) Where u' is the flashover voltage, D is the gap distance, and M and N are constants obtained by fitting.

8. The method for optimizing the parallel protection gap of lightning protection and ice protection insulators according to claim 1, characterized in that: The parallel protection gap distance is increased by a margin ΔD.

9. The method for optimizing the parallel protection gap of lightning protection and ice protection insulators according to claim 1, characterized in that: The tools for establishing electromagnetic transient models of transmission lines without lightning arresters and simulation models of lightning protection and ice protection insulators include ATP simulation software.

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