Method for determining parameters of protector of insulation device

Abstract

The invention belongs to the field of pipeline protection, particularly relates to a method for determining parameters of an insulation device protector, and aims to solve the problem of insufficient adaptability of a selected insulation protection device due to the fact that the type of strong current impact possibly suffered by the insulation device is not analyzed in the prior art. The method comprises the following steps: according to preset insulation device information, an installation mode and an installation position of an insulation device protector, setting an external strong current impact type which is probably generated by an insulation device; measuring sensor parameters of the insulation device protector, and calculating calculated values of various impact parameters based on the sensor parameters; and comparing the calculated value of the external impact, the electrical parameters of the insulation device and the protector parameters of the insulation device to obtain the parameters of the protector of the insulation device. According to the method, the type, the amplitude and the impact frequency of the strong current impact possibly suffered by the insulation device are judged and analyzed, so that the matching degree of the electrical parameters and the model selection of the finally determined insulation device protector is improved.

Description

Technical Field

[0001] The invention belongs to the field of pipeline protection, and in particular relates to a method for determining parameters of an insulating device protector. Background Art

[0002] Insulation devices (insulation devices, insulation flanges, insulation short pipes) play an important role in the cathodic protection of oil and gas pipelines, storage tanks and other projects, and can ensure the electrical insulation requirements of cathodic protection and the effective implementation of cathodic protection. Due to different installation locations and surrounding environments, insulation devices may be subject to external strong electrical shocks such as lightning currents, power frequency fault currents, and DC currents. Under the action of strong electrical shocks, it is possible to cause damage to the non-metallic polymer insulation and sealing materials inside the insulation device, causing the insulation device to fail. In severe cases, it may cause the sealing performance of the insulation device to decrease or even be lost, resulting in the leakage of flammable and explosive media sealed inside pipelines, storage tanks, etc. Therefore, it is extremely important to electrically protect the insulation device and avoid damage to its internal insulation and sealing materials for the effective implementation of cathodic protection and the safety of related facilities.

[0003] The petroleum industry standards "Electrical Insulation Standard for Cathodic Protection Pipelines" (SY / T 0086) and "Technical Specifications for Insulating Devices and Insulating Flanges" (SY / T 0516) do not specify the parameters of the protective devices of insulating devices. In actual engineering applications, there are many types of insulating device protectors, such as zinc oxide lightning arresters, equipotential connectors, spark gaps, solid-state decouplers, etc., but the electrical parameters of various protectors are different, and even vary greatly. The internal structure, working principle, installation method, life, detection method, etc. are also different.

[0004] At present, a common problem in the selection of insulating device protectors is that the type, amplitude, and frequency of strong electric shocks that the insulating device may be subjected to are not judged, analyzed, or calculated. Therefore, there is a great deal of arbitrariness in determining the electrical parameters and selection of insulating device protectors. Summary of the invention

[0005] In order to solve the above-mentioned problem in the prior art, that is, the problem that the insulation protection device selected is not sufficiently adaptable due to the failure to judge, analyze and calculate the type, amplitude and frequency of strong electric shocks that the insulation device may suffer, the present invention provides a method for determining the parameters of the insulation device protector, the method comprising:

[0006] Step S1, according to the pre-set insulation device information, installation mode and installation position of the insulation device protector, the type of external strong electric shock that the insulation device is likely to occur is set; the insulation device information includes the electrical parameters of the insulation device and the values ​​that the protector parameters of the insulation device should reach;

[0007] Step S2, measuring sensor parameters of the insulation device protector based on the type of external strong electric shock that occurs with probability, and calculating multiple shock parameters based on the sensor parameters;

[0008] Step S3, comparing the calculated value of the external impact, the electrical parameters of the insulating device and the values ​​that the protector parameters of the insulating device should reach, to obtain the parameters of the protector of the insulating device.

[0009] In some preferred embodiments, the types of external strong electric shocks that are likely to occur include: one or more of lightning current shocks, power frequency fault current shocks and direct current shocks.

[0010] In some preferred embodiments, the types of external strong electric shocks that may occur in the insulating device include:

[0011] The types of external strong electric shocks that are likely to occur based on the installation location, the types of external strong electric shocks that are likely to occur based on the installation method, and the types of external strong electric shocks that are likely to occur based on the installation area;

[0012] The types of external strong electric shocks that may occur based on the probability of obtaining the installation location include:

[0013] If it is installed in the process equipment area of ​​the station, the types of external strong electric shocks that are likely to occur are lightning current shock, power frequency fault current shock and DC current shock;

[0014] If installed in the valve room vent pipe, the types of external strong electric shock that may occur are lightning current shock and DC current shock;

[0015] If it is installed in the pipeline in and out of the storage tank, the type of external strong electric shock that is likely to occur is lightning current shock;

[0016] The types of external strong electric shocks that may occur based on the installation method include:

[0017] If the installation method is buried, the types of external strong electric shocks that are likely to occur are lightning current shock, power frequency fault current shock and DC current shock;

[0018] If the installation method is on the ground, the types of external strong electric shocks that are likely to occur are lightning current shock, power frequency fault current shock and DC current shock;

[0019] The types of external strong electric shocks that may occur based on the probability of being obtained in the installation area include:

[0020] If lightning strikes frequently occur in the installation area, the most likely type of external strong electric shock is lightning current shock;

[0021] If there is a high-voltage AC transmission line near the installation area, the types of external strong electric shocks that are likely to occur are lightning current shocks and power frequency fault current shocks;

[0022] If there is a DC converter station grounding electrode near the installation area, the most likely type of external strong electric shock to occur is a DC current shock.

[0023] In some preferred embodiments, the plurality of impact parameters include: lightning current impact parameters, power frequency fault current impact parameters, direct current impact parameters and external impact parameters suffered by the insulation device.

[0024] In some preferred embodiments, the lightning current impulse parameter is calculated as follows:

[0025] Obtain the lightning current I reaching the metal structure connected to the insulation device C , calculate the voltage E to the remote ground where the lightning current flows into the metal structure T :

[0026] E T =I C ·Z C

[0027] Among them, Z C The impedance of the metal path from the point where the lightning current strikes the surface of the structure to the insulating device;

[0028] Based on the impulse lightning current I reaching the metal structure connected to the insulation device C , and the voltage to the ground at the point where the lightning current flows into the metal structure E T , calculate the lightning current I reaching the joint of the insulating device I :

[0029]

[0030] Among them, γ represents the attenuation constant of the metal structure, R G represents the characteristic impedance of the metal structure, x1 is the transmission distance between the lightning current flowing into the structure and reaching the joint of the insulation device;

[0031] If the metal structure is buried, the characteristic impedance R G for:

[0032]

[0033] ρ is the resistance per unit length, g is the conductance per unit length;

[0034] If the metal structure is installed on the ground, R G =ρ;

[0035] The metal structure attenuation constant γ is:

[0036] γ=(ρ·g) 0.5

[0037] The lightning current I reaching the joint of the insulation device I for:

[0038]

[0039] h represents the distance from the grounding electrode to the pipeline;

[0040] The impedance Z of the metal path from the point where the lightning current strikes the surface of the structure to the insulating device C for:

[0041] Z C =R G ·cosh(γ·x1)

[0042] Lightning current I reaching the joint of the insulating device I That is the lightning current impulse parameter.

[0043] In some preferred embodiments, the lightning current impulse parameter is calculated by:

[0044] obtaining lightning current impulse parameters through the second lightning current impulse insulation device;

[0045] The second lightning current impulse insulation device includes a transmission line tower or a substation grounding electrode that is close to the pipeline. When the lightning current hits the tower or the ground wire on the tower, the lightning current flows to the buried grounding electrode through the tower or the down conductor;

[0046] The grounding system discharges the lightning current I to the soil F , coupled with the adjacent pipeline, the fault current is injected at point A of the pipeline, and the injected fault current is distributed to the upstream and downstream of the pipeline at point A. The current from the injection point to the upstream is I U and the current distributed downstream from the injection point and I D Then the lightning current flows along the pipeline to the nearest insulation device upstream and downstream of the pipeline respectively. The upstream current reaches point B of insulation device i, and the downstream current reaches point C of insulation device j. The currents of the lightning current reaching points B and C are I Ci and I Cj , which are the lightning current impulse parameters received by the upstream and downstream insulation devices respectively;

[0047] Among them, the impulse lightning current I reaching the pipeline injection point A I for:

[0048]

[0049] Z S is the soil resistance between the grounding system and the pipeline injection point A;

[0050]

[0051] ρ s represents the soil resistivity between the grounding system and the pipeline injection point A, and d represents the distance between the grounding system and the pipeline injection point A;

[0052] The current upstream of the injection point is I U and the current I distributed downstream from the injection point D for:

[0053]

[0054]

[0055] Z D is the pipeline impedance of the path from pipeline injection point A to insulation device j, Z U is the pipeline impedance of the path from pipeline injection point A to insulation device i;

[0056] Z U =R G ·cosh(γ·x2)

[0057] Where γ represents the pipeline attenuation constant, and x represents the transmission distance between the injection point A and the insulation device i;

[0058] Z D =R G ·cosh(γ·y)

[0059] y represents the distance between injection point A and insulating device j;

[0060] Voltage U at pipeline injection point A A for:

[0061]

[0062] Lightning current I reaching the insulating device i Ci for:

[0063]

[0064] R G is the characteristic impedance of the pipeline, h represents the distance from the grounding electrode to the pipeline;

[0065] The lightning current I reaching the insulating device i after sorting Ci for:

[0066]

[0067]

[0068] Lightning current I reaching the insulating device j Cj for:

[0069]

[0070] The lightning current I reaching the insulating device j after sorting Cj for:

[0071]

[0072]

[0073] Among them, the characteristic impedance R G for:

[0074]

[0075] ρ is the resistance per unit length, g is the conductance per unit length;

[0076] The decay constant γ is:

[0077] γ=(ρ·g) 0.5 .

[0078] In some preferred embodiments, the power frequency fault current impulse parameter is calculated in the same manner as the lightning current impulse parameter.

[0079] In some preferred embodiments, the DC current impact parameter is calculated as follows:

[0080] The point on the pipeline closest to the DC grounding electrode is marked as point A, d li The distance from point A is L i The unit length of the pipe section, V D The pipeline segment d is the closest to the DC grounding electrode. l1 The voltage on i The distance from the DC grounding electrode is r i The unit length of the pipe segment d li The voltage of i1 is the unit length pipeline section d closest to the DC grounding electrode. li The current flowing radially along the pipeline toward the insulating device;

[0081] Measure the earth potential rise of the soil outside the pipeline coating and obtain the distance L from point A. i Unit length of pipe segment d li At, pipe section d li The ground potential rise of the soil outside the coating is U i :

[0082]

[0083] ρ is the average resistivity, I g is the current discharged from the DC grounding electrode to the earth, r i The unit length of the pipe segment is d li Distance from DC grounding electrode;

[0084] The distance from the DC grounding electrode is r i The unit length of the pipe segment d li The voltage V i for:

[0085]

[0086] Z Pi The distance from point A is L i Pipe segment d li Unit length of pipeline section d li The grounding resistance, Z Ci The distance from point A is L i The unit length of the pipe segment d li The coating resistance;

[0087] The current I flowing to the insulation device at a certain unit length of pipeline section i for:

[0088]

[0089] The current I flowing to the insulation device at a certain unit length of the pipeline after sorting i for:

[0090]

[0091] The insulation device is subject to the unit length of the pipeline section d li The current I Li for:

[0092]

[0093] γ represents the attenuation constant of the pipeline, and L represents the length from point A to the insulating device;

[0094] When the pipe section from point A to the insulating device with a length of L is impacted by the DC grounding electrode into the ground current, the DC current impact parameters received by the insulating device are:

[0095]

[0096] i represents the total number of pipeline sections with a length of L from point A to the insulating device;

[0097]

[0098] Characteristic impedance R G for:

[0099] ρ is the resistance per unit length, g is the conductance per unit length;

[0100] The decay constant γ is:

[0101] γ=(ρ·g) 0.5

[0102] The insulation device is subject to the unit length of the pipeline section d li The current I Li That is the DC current impact parameter.

[0103] In some preferred embodiments, step S3 is:

[0104] For the current value of the insulating device protector, the current value constraint conditions must be met:

[0105] The calculated current value is less than the measured current value at which the insulation device is damaged and less than the minimum current value that the insulation device protector should have;

[0106] For the voltage value of the insulation device protector, the voltage value constraint conditions must be met:

[0107] The measured voltage value at which the insulation device is damaged > the calculated voltage value > the maximum voltage threshold that the insulation device protector should have.

[0108] Beneficial effects of the present invention:

[0109] (1) The present invention improves the matching degree of the electrical parameters and selection of the insulation device protector by judging and analyzing the type, amplitude, and frequency of strong electric shocks that the insulation device may suffer. BRIEF DESCRIPTION OF THE DRAWINGS

[0110] Other features, objects and advantages of the present application will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings:

[0111] Figure 1 is a flow chart of a method for determining parameters of an insulating device protector in an embodiment of the present invention;

[0112] Figure 2 is a flow chart of determining the type of external strong electric shock that is likely to occur to an insulation device protector in an embodiment of the present invention;

[0113] Figure 3is a schematic diagram of the principle of determining multiple impact parameters in an embodiment of the present invention;

[0114] Figure 4 is a logic diagram for determining the type and amplitude of lightning strikes suffered by an insulating device in an embodiment of the present invention;

[0115] Figure 5 is a lightning current amplitude probability curve used in calculating the insulating device struck by lightning by the regulation method in the embodiment of the present invention;

[0116] Figure 6 is a circuit schematic diagram of a first lightning impulse insulation device in an embodiment of the present invention;

[0117] Figure 7 is a circuit schematic diagram of a second lightning impulse insulation device in an embodiment of the present invention, and is also a circuit schematic diagram of a fault current impulse insulation device;

[0118] Figure 8 It is a schematic diagram of the principle of a DC grounding electrode causing a DC impact on an insulation device in an embodiment of the present invention;

[0119] Fig. 9 A circuit schematic diagram of a unit length pipeline section injecting current to impact the insulation device when a DC grounding electrode causes the insulation device to be impacted by DC in an embodiment of the present invention;

[0120] Fig.10 It is a schematic diagram of the effect of the lightning strike position that may be suffered when a typical insulation device is installed on the ground in an embodiment of the present invention;

[0121] Fig.11 It is a lightning current amplitude distribution probability curve measured at a certain place extracted from a certain document and a lightning current amplitude distribution probability curve in the regulations;

[0122] Fig.12 A typical underground installation of an insulating device in an embodiment of the present invention, a lightning strike position and its relative position relationship with the insulating device;

[0123] Fig.13 It is a schematic diagram of a lightning current / fault current impulse insulation device for a transmission line tower grounding electrode according to an embodiment of the present invention;

[0124] Fig.14 It is a schematic diagram of a DC grounding electrode causing a DC shock to an insulation device in an embodiment of the present invention. DETAILED DESCRIPTION

[0125] The present application will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the relevant invention, rather than to limit the invention. It is also necessary to explain that, for ease of description, only the parts related to the relevant invention are shown in the accompanying drawings.

[0126] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0127] In order to more clearly explain the method for determining the parameters of the insulating device protector of the present invention, the following is combined with Figure 1 Each step in the embodiment of the present invention is described in detail.

[0128] The method for determining the parameters of the insulating device protector according to the first embodiment of the present invention includes steps S1 to S3, each of which is described in detail as follows:

[0129] Step S1, according to the pre-set insulation device information, installation mode and installation position of the insulation device protector, the type of external strong electric shock that the insulation device is likely to occur is set; the insulation device information includes the electrical parameters of the insulation device and the values ​​that the protector parameters of the insulation device should reach;

[0130] In this embodiment, the types of external strong electric shocks that may occur include: one or more of lightning current shock, power frequency fault current shock and direct current shock. In addition, whether it is subject to direct current shock depends on whether there is a direct current grounding electrode near the pipeline. Usually, a pipeline within a few tens of meters to 20 km may be subject to a relatively strong shock, depending on the specific soil geological structure, pipeline length, anti-corrosion layer status, and insulation device location.

[0131] In this embodiment, the type of external strong electric shock that may occur when the insulating device is set is as follows: Figure 2 As shown, specifically including:

[0132] The types of external strong electric shocks that are likely to occur based on the installation location, the types of external strong electric shocks that are likely to occur based on the installation method, and the types of external strong electric shocks that are likely to occur based on the installation area;

[0133] The types of external strong electric shocks that may occur based on the probability of obtaining the installation location include:

[0134] If it is installed in the process equipment area of ​​the station, the types of external strong electric shocks that are likely to occur are lightning current shock, power frequency fault current shock and DC current shock;

[0135] Lightning current comes from two situations: the process equipment area includes a large number of above-ground pipelines, steel structures, etc. These facilities are susceptible to lightning strikes, and the insulation devices will be directly or indirectly connected to the above-ground pipelines. After striking the above-ground pipelines and steel structures, the lightning current will be transmitted to the insulation devices; if there is a grounding electrode of a high-voltage transmission system near the line pipeline outside the process station, such as the grounding electrode of a high-voltage tower of the transmission system or the grounding electrode system of a substation, when the transmission line is struck by lightning, the lightning current will be discharged into the soil through the grounding system of the above-mentioned transmission system. If there are buried pipelines near these grounding systems, the grounding system will be coupled with the pipelines, and the lightning current will be transmitted through the pipelines to the insulation devices of the oil and gas pipeline station, and the insulation devices will be struck by the lightning current. The power frequency fault current generally comes from the line pipeline bounded by the insulation device in the station. The source of the power frequency fault current suffered by the line pipeline comes from the grounding electrode of the high-voltage tower of the AC transmission system or the grounding electrode system of the substation. When the AC transmission system fails, such as a single-phase grounding fault between the phase line and the ground line at the tower, the power frequency fault current in the phase line will enter the ground through the tower grounding system. The grounding system will couple with the pipeline. The power frequency fault current is transmitted to the insulation device of the oil and gas pipeline station through the pipeline, and the insulation device is impacted by the power frequency fault current. The DC current impact comes from the ground current of the grounding electrode of the nearby DC transmission line converter station. When the DC transmission line operates in a single-phase large-scale return mode, the ground current of the grounding electrode can impact the line pipeline and the buried pipeline in the station, causing a DC voltage difference on both sides of the insulation device.

[0136] If installed in the valve room vent pipe, the types of external strong electric shock that may occur are lightning current shock and DC current shock;

[0137] When lightning strikes the vent pipe of the valve room or the above-ground pipelines, steel structures and other metal facilities in the valve room, the lightning current will be transmitted to the insulating device through the above-mentioned metal facilities, and the insulating device will be struck by the lightning current.

[0138] The DC current surge comes from the ground current of the grounding electrode of the nearby DC transmission line converter station. When the DC transmission line operates in a single-pole return mode, the ground current of the grounding electrode can impact the buried pipeline in the valve room, causing a DC voltage difference on both sides of the insulation device.

[0139] Considering the installation location of the insulating device and the certain safety distance requirements between the valve room and the towers and substations of the AC power transmission system, the possibility of the insulating device in this area being impacted by power frequency fault current is extremely low.

[0140] If it is installed in the pipeline in and out of the storage tank, the type of external strong electric shock that is likely to occur is lightning current shock;

[0141] When lightning strikes the tank wall, tank top and other parts, the lightning current will be conducted along the tank wall to the insulating device installed at the pipes in and out of the tank, or the lightning current will directly strike the insulating device installed at the pipes in and out of the tank, and the insulating device will be struck by the lightning current.

[0142] The types of external strong electric shocks that may occur based on the installation method include:

[0143] If the installation method is buried, the types of external strong electric shocks that are likely to occur are lightning current shock, power frequency fault current shock and DC current shock;

[0144] If the insulating device is installed underground, it may be impacted by strong electricity that can penetrate into the ground. Since the insulating device is buried underground, the strong electricity is generally transmitted to the insulating device through pipelines, steel structures, etc., and the insulating device will not be directly impacted by the strong electricity. According to the above analysis, when the insulating device is installed underground, it can be impacted by strong electricity including lightning current, power frequency fault current and DC current.

[0145] If the installation method is on the ground, the types of external strong electric shocks that are likely to occur are lightning current shock, power frequency fault current shock and DC current shock; the effects of the installation method on the ground are as follows: Fig.10 As shown, in Fig.10 In the figure, position 1 indicates that the lightning current directly strikes the insulating layer outside the insulating joint; positions 2 and 2' indicate that the lightning current directly strikes the connection between the insulating joint and the aboveground pipeline; positions 3 and 3' indicate that the lightning current directly strikes the vicinity of the connection between the insulating joint and the aboveground pipeline.

[0146] According to the above analysis, the insulation device is installed above the ground and may be directly struck by lightning. The above analysis shows that the power frequency fault current and DC current are the AC or DC grounding electrode current coupled with the pipeline, and transmitted to the pipeline through the soil. The lightning current can also be indirectly transmitted to the insulation device by impacting the pipeline and steel structure on the ground. Therefore, when the insulation device is installed above the ground, it may be subjected to strong electrical shocks including lightning current, power frequency fault current, and DC current.

[0147] The types of external strong electric shocks that may occur based on the probability of being obtained in the installation area include:

[0148] If lightning strikes frequently occur in the installation area, the most likely type of external strong electric shock is lightning current shock;

[0149] If lightning strikes frequently in the area where the insulating device is installed, the insulating device is more likely to be struck by direct or indirect lightning, and the insulating device is susceptible to lightning current shocks.

[0150] If there is a high-voltage AC transmission line near the installation area, the types of external strong electric shocks that are likely to occur are lightning current shocks and power frequency fault current shocks;

[0151] If there is a high-voltage AC transmission line near the pipeline, the pipeline is likely to be impacted by the fault current of the AC transmission line grounding electrode (at the tower or substation), and the insulation device is susceptible to the power frequency fault current impact.

[0152] If there is a DC converter station grounding electrode near the installation area, the most likely type of external strong electric shock to occur is a DC current shock.

[0153] If there is a DC converter station grounding electrode near the pipeline, when the DC transmission line operates in a single-pole return mode, the ground current of the DC converter station grounding electrode will couple with the nearby pipeline, and the insulation device will be susceptible to DC current shocks.

[0154] Step S2, based on the type of external strong electric shock that occurs with probability, measure the sensor parameters of the insulation device protector, and calculate multiple shock parameters based on the sensor parameters, such as Figure 3 As shown;

[0155] In this embodiment, the logic diagram for determining the type and amplitude of lightning strikes suffered by the insulation device is as follows: Figure 4 shown.

[0156] In this embodiment, the multiple impact parameters include: lightning current impact parameters, power frequency fault current impact parameters, direct current impact parameters and external impact parameters suffered by the insulation device.

[0157] Usually, the calculation of lightning current impulse parameters can be carried out by the code method. The principle of the code method is that if the insulation device is installed on the ground and the lightning frequency in the installation area is high, it is judged that the insulation device is susceptible to direct lightning impact; the prior art "Research on Simultaneous Faults of Double Circuits on the Same Tower of 750kV Double Circuit Lines in Northwest China" (Proceedings of the 2007 Academic Annual Meeting of the High Voltage Committee of the Chinese Society of Electrical Engineering) clearly records the lightning current amplitude distribution probability curve measured in Yulin, Shaanxi Province and the lightning current amplitude distribution probability curve in the code, such as Fig.11 shown.

[0158] In the power industry, the lightning current amplitude probability is generally calculated using the DL / T 620-1997 method. The probability of the lightning current amplitude exceeding I in a general area is:

[0159]

[0160] Where P is the lightning current amplitude probability; I is the lightning current amplitude;

[0161] The lightning current amplitude is relatively small in the northwest region outside southern Shaanxi and parts of the Inner Mongolia Autonomous Region (the average annual number of thunderstorm days in these areas is generally 20 or less). The probability that the lightning current amplitude in these areas exceeds I is:

[0162]

[0163] Among them, P is the lightning current amplitude probability; I is the lightning current amplitude.

[0164] The lightning current amplitude probability curve calculated by the regulation method is as follows: Figure 5 As shown, it can be used as a reference when calculating the parameters of an insulating device subjected to lightning strikes, that is, when an insulating device is directly struck by lightning, the lightning current amplitude can be determined by looking up the curve. Figure 5 It is a lightning current amplitude probability curve calculated by the code method, which can be used to calculate the parameters of the insulating device subjected to lightning strikes. That is, when the insulating device is directly struck by lightning, the lightning current amplitude can be determined by looking up the curve.

[0165] In this embodiment, the lightning current impulse parameter is calculated as follows:

[0166] The first lightning impulse insulation device used in this embodiment is as follows Figure 6 As shown;

[0167] Obtain the lightning current I reaching the metal structure connected to the insulation device C , calculate the voltage E to the remote ground where the lightning current flows into the metal structure T :

[0168] E T =I C ·Z C

[0169] Among them, Z C The impedance of the metal path from the point where the lightning current strikes the surface of the structure to the insulating device;

[0170] Based on the impulse lightning current I reaching the metal structure connected to the insulation device C , and the voltage to the ground at the point where the lightning current flows into the metal structure E T , calculate the lightning current I reaching the joint of the insulating device I :

[0171]

[0172] Among them, γ represents the attenuation constant of the metal structure, R G represents the characteristic impedance of the metal structure, x1 is the transmission distance between the lightning current flowing into the structure and reaching the joint of the insulation device;

[0173] If the metal structure is buried, the characteristic impedance R G for:

[0174]

[0175] ρ is the resistance per unit length, g is the conductance per unit length;

[0176] If the metal structure is installed on the ground, R G =ρ;

[0177] The metal structure attenuation constant γ is:

[0178] γ=(ρ·g) 0.5

[0179] The lightning current I reaching the joint of the insulation device I for:

[0180]

[0181] The impedance Z of the metal path from the point where the lightning current strikes the surface of the structure to the insulating device C for:

[0182] Z C =R G ·cosh(γ·x1)

[0183] Lightning current I reaching the joint of the insulating device I That is the lightning current impulse parameter.

[0184] In this embodiment, the lightning current impulse parameter is calculated by:

[0185] The lightning current impulse parameter is obtained by the second lightning current impulse insulation device; the second lightning current impulse insulation device is as follows: Figure 7 As shown, Figure 7 It also serves as the circuit schematic of the fault current impulse insulation device;

[0186] The second lightning current impulse insulation device includes a transmission line tower or a substation grounding electrode that is close to the pipeline. When the lightning current hits the tower or the ground wire on the tower, the lightning current flows to the buried grounding electrode through the tower or the down conductor;

[0187] The grounding system discharges the lightning current I to the soil F , coupled with the adjacent pipeline, the fault current is injected at point A of the pipeline, and the injected fault current is distributed to the upstream and downstream of the pipeline at point A. The current from the injection point to the upstream is I U and the current distributed downstream from the injection point and I D Then the lightning current flows along the pipeline to the nearest insulation device upstream and downstream of the pipeline respectively. The upstream current reaches point B of insulation device i, and the downstream current reaches point C of insulation device j. The currents of the lightning current reaching points B and C are I Ci and I Cj , which are the lightning current impulse parameters received by the upstream and downstream insulation devices respectively;

[0188] Among them, the impulse lightning current I reaching the pipeline injection point A I for:

[0189]

[0190] Z S is the soil resistance between the grounding system and the pipeline injection point A;

[0191]

[0192] ρ s represents the soil resistivity between the grounding system and the pipeline injection point A, and d represents the distance between the grounding system and the pipeline injection point A;

[0193] The current upstream of the injection point is I U and the current I distributed downstream from the injection point D for:

[0194]

[0195]

[0196] Z D is the pipeline impedance of the path from pipeline injection point A to insulation device j, Z U is the pipeline impedance of the path from pipeline injection point A to insulation device i;

[0197] Z U =R G ·cosh(γ·x2)

[0198] Where γ represents the pipeline attenuation constant, and x represents the transmission distance between the injection point A and the insulation device i;

[0199] Z D =R G ·cosh(γ·y)

[0200] y represents the distance between injection point A and insulating device j;

[0201] Voltage U at pipeline injection point A A for:

[0202]

[0203] Lightning current I reaching the insulating device i Ci for:

[0204]

[0205] R G is the characteristic impedance of the pipeline;

[0206] The lightning current I reaching the insulating device i after sorting Ci for:

[0207]

[0208]

[0209] Lightning current I reaching the insulating device j Cj for:

[0210]

[0211] The lightning current I reaching the insulating device j after sorting Cj for:

[0212]

[0213]

[0214] Among them, the characteristic impedance R G for:

[0215]

[0216] ρ is the resistance per unit length, g is the conductance per unit length;

[0217] The decay constant γ is:

[0218] γ=(ρ·g) 0.5 .

[0219] In this embodiment, the power frequency fault current impulse parameter is calculated in the same way as the lightning current impulse parameter. Figure 7 As shown, the calculation method is:

[0220] The impulse lightning current I reaching the pipeline injection point A I for:

[0221]

[0222] Z S is the soil resistance between the grounding system and the pipeline injection point A;

[0223]

[0224] ρ s represents the soil resistivity between the grounding system and the pipeline injection point A, and d represents the distance between the grounding system and the pipeline injection point A;

[0225] The current upstream of the injection point is I Uand the current I distributed downstream from the injection point D for:

[0226]

[0227]

[0228] Z D is the pipeline impedance of the path from pipeline injection point A to insulation device j, Z U is the pipeline impedance of the path from pipeline injection point A to insulation device i;

[0229] Z U =R G ·cosh(γ·x2)

[0230] Where γ represents the pipeline attenuation constant, and x represents the transmission distance between the injection point A and the insulation device i;

[0231] Z D =R G ·cosh(γ·y)

[0232] y represents the distance between injection point A and insulating device j;

[0233] Voltage U at pipeline injection point A A for:

[0234]

[0235] Lightning current I reaching the insulating device i Ci for:

[0236]

[0237] R G is the characteristic impedance of the pipeline, h represents the distance from the grounding electrode to the pipeline;

[0238] The lightning current I reaching the insulating device i after sorting Ci for:

[0239]

[0240]

[0241] Lightning current I reaching the insulating device j Cj for:

[0242]

[0243] The lightning current I reaching the insulating device j after sorting Cj for:

[0244]

[0245]

[0246] Among them, the characteristic impedance R G for:

[0247]

[0248] ρ is the resistance per unit length, g is the conductance per unit length;

[0249] The decay constant γ is:

[0250] γ=(ρ·g) 0.5 .

[0251] In this embodiment, the DC current impact parameter is calculated as follows:

[0252] The point on the pipeline closest to the DC grounding electrode is marked as point A, d li The distance from point A is L i The unit length of the pipe section, V D The pipeline segment d is the closest to the DC grounding electrode. l1 The voltage on i The distance from the DC grounding electrode is r i The unit length of the pipe segment d li The voltage of i1 is the unit length pipeline section d closest to the DC grounding electrode. li The current flows radially along the pipeline toward the insulating device; the principle of the DC grounding electrode causing the insulating device to be subjected to DC shock is as follows Figure 8 As shown, the circuit status of the insulation device protector at this time is as follows Fig. 9 As shown;

[0253] Measure the earth potential rise of the soil outside the pipeline coating and obtain the distance L from point A. i Unit length of pipe segment d li At, pipe section d li The ground potential rise of the soil outside the coating is U i :

[0254]

[0255] ρ is the average resistivity, I g is the current discharged from the DC grounding electrode to the earth, r i The unit length of the pipe segment is d li Distance from DC grounding electrode;

[0256] The distance from the DC grounding electrode is r i The unit length of the pipe segment d li The voltage Vi for:

[0257]

[0258] Z Pi The distance from point A is L i Pipe segment d li Unit length of pipeline section d li The grounding resistance, Z Ci The distance from point A is L i The unit length of the pipe segment d li The coating resistance;

[0259] The current I flowing to the insulation device at a certain unit length of pipeline section i for:

[0260]

[0261] The current I flowing to the insulation device at a certain unit length of the pipeline after sorting i for:

[0262]

[0263] The insulation device is subject to the unit length of the pipeline section d li The current I Li for:

[0264]

[0265] γ represents the attenuation constant of the pipeline, and L represents the length from point A to the insulating device;

[0266] When the pipe section from point A to the insulating device with a length of L is impacted by the DC grounding electrode into the ground current, the DC current impact parameters received by the insulating device are:

[0267]

[0268] i represents the total number of pipeline sections with a length of L from point A to the insulating device;

[0269]

[0270] Characteristic impedance R G for:

[0271] ρ is the resistance per unit length, g is the conductance per unit length;

[0272] The decay constant γ is:

[0273] γ=(ρ·g) 0.5

[0274] The insulation device is subject to the unit length of the pipeline section d li The current I Li That is the DC current impact parameter.

[0275] Step S3, comparing the calculated value of the external impact, the electrical parameters of the insulating device and the values ​​that the protector parameters of the insulating device should reach, to obtain the parameters of the protector of the insulating device.

[0276] In this embodiment, step S3 is:

[0277] For the current value of the insulating device protector, the current value constraint conditions must be met:

[0278] The calculated current value is less than the measured current value at which the insulation device is damaged and less than the minimum current value that the insulation device protector should have;

[0279] For the voltage value of the insulation device protector, the voltage value constraint conditions must be met:

[0280] The measured voltage value at which the insulation device is damaged > the calculated voltage value > the maximum voltage threshold that the insulation device protector should have.

[0281] Combination Fig.10 and Fig.11 The calculation of the insulation device installed above the ground in Yulin, Shaanxi Province by the code method is demonstrated, and the determination method and steps when lightning strikes different parts are analyzed under the condition of known lightning current amplitude distribution probability curve.

[0282] First determine the lightning current amplitude:

[0283] The principle for determining the lightning current amplitude is to comprehensively consider the lightning current amplitude in the area where the insulating device is located and its relationship with the lightning current probability distribution, so as to ensure that the insulating device protector can withstand the impact of the maximum lightning current that may occur, so as to protect the insulating device from damage caused by the lightning current impact. However, generally, the larger the lightning current amplitude, the lower the probability of occurrence, the higher the threshold of the selected insulating device protector, the higher the price of the insulating device protector, and the larger the size.

[0284] from Fig.11 It can be seen that when the probability is less than 50%, the measured value is smaller than the national regulations and the Northwest regulations, and the measured value is larger than the Northwest regulations. When the probability is less than 50%, the measured value should be used as the basis and the appropriate lightning current amplitude should be taken at the appropriate probability. Fig.11It can be seen that the maximum measured lightning current amplitude is 80kA. For commonly used switch-type protectors and combined surge protectors, such as spark gaps and solid-state decouplers, 80kA can generally meet the requirements and have appropriate sizes. However, for voltage-limiting protectors such as zinc oxide lightning arresters, if the lightning current amplitude reaches 80kA, the size of the protector will be particularly large and difficult to install. Moreover, such protectors are not explosion-proof and are not safe when used in oil and gas pipelines. Therefore, although the probability of a lightning current amplitude of 80kA is extremely low, it is a more reasonable value based on comprehensive considerations.

[0285] Determine the impact position of the lightning current, position 1, position 2 and position 2', which is equivalent to the lightning current directly impacting the insulating device body; for position 3 and position 3', although they are a certain distance away from the insulating device body, for the same insulating device, the probability of the lightning current impacting position 1, position 2, position 2', position 3 and position 3' is the same. Therefore, the lightning current amplitude should be determined according to the most serious situation, that is, position 1, position 2 and position 2'. According to the analysis of 1), although the probability of a lightning current amplitude of 80kA is extremely low, it is a relatively reasonable value based on comprehensive considerations. Therefore, the lightning current threshold of the insulating device protector in this example is 80kA, that is, the amplitude of the lightning current impact of the insulating device protector should not be less than 80kA.

[0286] A second embodiment of the present invention discloses a method for determining parameters of an insulating device protector when the insulating device protector is installed underground.

[0287] In this embodiment, the lightning strike position is as follows: Fig.12 As shown, lightning first strikes the above-ground pipeline and then is transmitted to the buried insulation device through the above-ground pipeline. Point 1 is the lightning strike point, point 2 is the interface between the above-ground pipeline and the buried pipeline, and point 3 is the boundary between the buried pipeline and the buried insulation device, that is, the point where lightning strikes the insulation device.

[0288] The lightning current impulse parameters are calculated by the method of the first embodiment of the present invention:

[0289] The pipe diameter is 914 mm, the wall thickness is 12.7 mm, and the line resistivity ρ of the pipe is 2.06×10 -5 Ω·cm, the length of the above-ground pipeline (point 1 to point 2) is 50m, the length of the buried pipeline (point 2 to point 3) is 50m, and the soil resistivity is 100Ω·m. The characteristic conductivity of the buried pipeline in the soil with a soil resistivity of 10Ω·m is 1×10 -5 S·m -2 , the lightning current amplitude is I T 100kA.

[0290] Take the pipeline length of 1m as the unit length, then the buried pipeline to the ground unit length conductivity

[0291] g = 1 × 10 -5 ×10×π×0.914×1=2.87×10 -4 S

[0292] The buried pipeline attenuation constant γ is:

[0293]

[0294] Characteristic resistance R of buried pipeline G for:

[0295]

[0296] The impedance of the metal path from the point where the lightning current strikes the surface of the structure to the insulating device, that is, the pipeline impedance of points 1 to 3, Z C =R G ·cosh(γ·x)=0.14×cosh(4.05×10 -5 ×100)=0.14Ω

[0297] The lightning current impulse parameters that finally reach point 3 are:

[0298]

[0299] The third embodiment of the present invention discloses a method for determining parameters of an insulation device protector by using a lightning current that impacts an insulation device protector when entering a grounding electrode of a transmission line tower.

[0300] The method for obtaining lightning current impulse parameters through the second lightning current impulse insulation device as in the first embodiment of the present invention;

[0301] In this embodiment, the effect of the impact on the insulation device protector is as follows: Fig.13 As shown, lightning first strikes the transmission line tower or ground wire, and the lightning current flows to the buried grounding electrode through the tower or down conductor. The grounding system discharges the lightning current to the soil, couples with the nearby pipeline, and injects the fault current at point 1 of the pipeline. The injected lightning current is distributed to the upstream and downstream of the pipeline at point 1, and the lightning current flows along the pipeline to the nearest insulating device upstream and downstream of the pipeline respectively. The upstream current reaches point 2 of the insulating device, and the downstream current reaches point 3 of the insulating device.

[0302] The pipe diameter is 914 mm, the wall thickness is 12.7 mm, and the line resistivity ρ of the pipe is 2.06×10 -5Ω·cm, upstream pipeline length (point 1 to point 2) 25m, downstream pipeline length (point 1 to point 3) 75m, soil resistivity 100Ω·m. The characteristic conductivity of a buried pipeline in a soil with a soil resistivity of 10Ω·m is 1×10 -5 S·m -2 , the lightning current amplitude is 100kA, and the distance between the grounding electrode and the pipeline is 5m.

[0303] The relevant calculation process and results are as follows:

[0304] Take the pipeline length of 1m as the unit length, then the buried pipeline to the ground unit length conductivity

[0305] g = 1 × 10 -5 ×10×π×0.914×1=2.87×10 -4 S

[0306] Attenuation constant of buried pipeline

[0307]

[0308] Characteristic resistance of buried pipelines

[0309]

[0310] The amplitude of the lightning current injection point on the pipeline is:

[0311]

[0312] Impedance Z of the pipeline between the lightning current injection point 1 and the point 2 of the insulation device on the pipeline U for:

[0313] Z U =R G ·cosh(γ·x)=0.14×cosh(4.05×10 -5 ×25×10 3 )=0.22Ω

[0314] Impedance Z of the pipeline between the lightning current injection point 1 and the point 3 of the insulation device on the pipeline D for:

[0315] Z D =R G ·cosh(γ·y)=0.14×cosh(4.05×10 -5 ×75×10 3 )=1.46Ω

[0316] The voltage at pipeline injection point 1 is calculated as follows:

[0317]

[0318] From the pipeline injection point 1, the lightning current flowing to the upstream and downstream of the pipeline is:

[0319] Lightning current flowing from pipeline injection point 1 to insulation device point 2:

[0320]

[0321] Lightning current flowing from pipeline injection point 1 to insulation device point 3:

[0322]

[0323] The lightning current reaching point 2 of the insulating device is calculated as follows,

[0324]

[0325] The lightning current reaching point 3 of the insulating device is calculated as follows,

[0326]

[0327] A fourth embodiment of the present invention discloses a method for determining parameters of a protector of an insulation device of a transmission line tower grounding electrode ground fault current impact insulation device;

[0328] The power frequency fault current impact parameter is calculated by the method described in the first embodiment of the present invention:

[0329] When a fault occurs in the transmission line system, the transmission line tower or substation grounding electrode close to the pipeline will discharge the fault current to the soil through the grounding system, couple with the nearby pipeline, and inject the fault current at point 1 of the pipeline. The injected fault current is distributed to the upstream and downstream of the pipeline at point 1, and the fault current flows along the pipeline to the nearest insulating device upstream and downstream of the pipeline respectively. The upstream current reaches point 2 of the insulating device, and the downstream current reaches point 3 of the insulating device.

[0330] The pipe diameter is 914 mm, the wall thickness is 12.7 mm, and the line resistivity ρ of the pipe is 2.06×10 -5 Ω·cm, upstream pipeline length (point 1 to point 2) 25m, downstream pipeline length (point 1 to point 3) 75m, soil resistivity 100Ω·m. The characteristic conductivity of a buried pipeline in a soil with a soil resistivity of 10Ω·m is 1×10 -5 S·m -2 , the fault current amplitude is 30kA, and the distance between the grounding electrode and the pipeline is 5m.

[0331] The relevant calculation process and results are as follows:

[0332] Take the pipeline length of 1m as the unit length, then the buried pipeline to the ground unit length conductivity

[0333] g = 1 × 10 -5 ×10×π×0.914×1=2.87×10 -4 S

[0334] Attenuation constant of buried pipeline

[0335]

[0336] Characteristic resistance of buried pipelines

[0337]

[0338] The amplitude of the fault current injection point on the pipeline is:

[0339]

[0340] Impedance Z of the pipeline between the fault current injection point 1 and the point 2 of the insulation device on the pipeline U for:

[0341] Z U =R G ·cosh(γ·x)=0.14×cosh(4.05×10 -5 ×25×10 3 )=0.22Ω

[0342] Impedance Z of the pipeline between the fault current injection point 1 and the point 3 of the insulation device on the pipeline D for:

[0343] Z D =R G ·cosh(γ·y)=0.14×cosh(4.05×10 -5 ×75×10 3 )=1.46Ω

[0344] The voltage U1 at the pipeline injection point 1 is calculated as follows:

[0345]

[0346] From the pipeline injection point 1, the lightning current flowing to the upstream and downstream of the pipeline is:

[0347] Lightning current I flowing from pipeline injection point 1 to insulation device point 2 U :

[0348]

[0349] Lightning current I flowing from pipeline injection point 1 to insulation device point 3 D :

[0350]

[0351] The fault current reaching point 2 of the isolating device is calculated as follows,

[0352]

[0353] The fault current reaching point 3 of the insulation device is calculated as follows,

[0354]

[0355] A fifth embodiment of the present invention discloses a method for determining parameters of a protector of an insulating device when a DC grounding electrode causes a DC shock to the insulating device;

[0356] When the DC grounding electrode is used in the DC transmission line with a single pole return mode, a DC current will pass through the grounding electrode into the ground and couple with the nearby buried pipeline, causing the pipeline potential along the pipeline to change and generate current in the pipeline. The current is conducted radially along the pipeline to the insulation device. The specific effects are as follows: Fig.14 As shown;

[0357] The DC current impulse parameters are calculated by the method described in the first embodiment of the present invention; the pipeline diameter is 914 mm, the wall thickness is 12.7 mm, the pipeline burial depth is 1.5 m, and the line resistivity ρ of the pipeline is 2.06×10 -5 Ω·cm, the insulation resistance of the anti-corrosion layer is 1×10 5 Ω·m 2 , soil resistivity is 100Ω·m. The characteristic resistance of a buried pipeline in soil with a soil resistivity of 10Ω·m is 1×10 -5 Ω·m 2 , the grounding current of the grounding electrode is 3000A, the distance between the grounding electrode and the pipeline is 5km, and the unit pipeline section d li The length is taken as 1 km, and the unit pipeline section d li The surface area is 2871.42m 2 The length of the pipeline (from point 1 to point 2) is 10 km, and the 10 km pipeline is divided into 10 sections (i=1~10).

[0358] There are two points that need to be explained. First, the unit pipeline section length of 1 km is obtained in this embodiment in order to explain the calculation process adopted by the present invention. In actual use, the smaller the value of the unit pipeline section length is, the higher the calculation accuracy is, but the corresponding calculation time is longer; second, the pipeline route assumed in this embodiment is a straight line, which is a necessary simplification for explaining the calculation process adopted by the present invention. The actual pipeline direction may be an irregular curve shape in most cases due to various reasons. The calculation idea and process are the same, but it is more complicated than the process shown in this embodiment.

[0359] The relevant calculation process and results are as follows:

[0360] Taking the pipeline length of 1 km as the unit length, the ground conductance g of the buried pipeline per unit length is:

[0361] g = 1 × 10 -5 ×10×π×0.914×1000=0.287S

[0362] The buried pipeline attenuation constant γ is:

[0363]

[0364] Characteristic resistance R of buried pipeline G for:

[0365]

[0366] The distance L between the i-th segment (center point) and point 1 i for:

[0367] L i =(2i-1)×500

[0368] The distance r between the i-th segment (center point) and the DC grounding electrode i for:

[0369] r i =(L i 2 +h 2 ) 0.5

[0370] The ground potential rises at the i-th segment (center point) i for:

[0371]

[0372] The grounding resistance Z of the i-th pipeline section Pi for:

[0373]

[0374] The coating resistance Z of the i-th pipeline section Ci for:

[0375]

[0376] Pipeline voltage V at the i-th segment (center point) i for:

[0377]

[0378] The current I flowing to the insulating device in the i-th section (center point) of the pipeline i for:

[0379]

[0380] At the point 2 of the insulation device, the impulse current I of the DC current at the i-th section of the pipeline Li for:

[0381]

[0382] The calculation results are shown in Table 1;

[0383] Table 1 Calculation results of DC impulse current for different pipeline sections

[0384] Under the conditions of this embodiment, the DC impulse current borne by the insulating joint point 2 is 1.97A.

[0385] Although the various steps in the above embodiment are described in the above-mentioned order, those skilled in the art can understand that in order to achieve the effect of this embodiment, different steps do not have to be executed in such an order. They can be executed simultaneously (in parallel) or in a reverse order. These simple changes are within the scope of protection of the present invention.

[0386] The terms "first", "second", etc. are used to distinguish similar objects rather than to describe or indicate a particular order or sequence.

[0387] The term "comprise" or any other similar term is intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus / device that includes a list of elements includes not only those elements but also other elements not expressly listed, or also includes elements inherent to such process, method, article, or apparatus / device.

[0388] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. A method for determining parameters of an insulating device protector, characterized in that: The method comprises: Step S1, according to the pre-set insulation device information, installation mode and installation position of the insulation device protector, the type of external strong electric shock that the insulation device is likely to occur is set; the insulation device information includes the electrical parameters of the insulation device and the values ​​that the protector parameters of the insulation device should reach; Step S2, measuring sensor parameters of the insulation device protector based on the type of external strong electric shock that occurs with probability, and calculating values ​​of multiple shock parameters based on the sensor parameters; Step S3, comparing the calculated value of the external impact, the electrical parameters of the insulating device and the values ​​that the protector parameters of the insulating device should reach, to obtain the parameters of the protector of the insulating device.

2. The method for determining the parameters of an insulating device protector according to claim 1, characterized in that: The types of external strong electric shocks that may occur with probability include: one or more of lightning current shocks, power frequency fault current shocks and direct current shocks.

3. The method for determining the parameters of an insulating device protector according to claim 2, characterized in that: The types of external strong electric shocks that may occur when setting the insulation device include: The types of external strong electric shocks that are likely to occur based on the installation location, the types of external strong electric shocks that are likely to occur based on the installation method, and the types of external strong electric shocks that are likely to occur based on the installation area; The types of external strong electric shocks that may occur based on the probability of obtaining the installation location include: If it is installed in the process equipment area of ​​the station, the types of external strong electric shocks that are likely to occur are lightning current shock, power frequency fault current shock and DC current shock; If installed in the valve room vent pipe, the types of external strong electric shock that may occur are lightning current shock and DC current shock; If it is installed in the pipeline in and out of the storage tank, the type of external strong electric shock that is likely to occur is lightning current shock; The types of external strong electric shocks that may occur based on the installation method include: If the installation method is buried, the types of external strong electric shocks that are likely to occur are lightning current shock, power frequency fault current shock and DC current shock; If the installation method is on the ground, the types of external strong electric shocks that are likely to occur are lightning current shock, power frequency fault current shock and DC current shock; The types of external strong electric shocks that may occur based on the probability of being obtained in the installation area include: If lightning strikes frequently occur in the installation area, the most likely type of external strong electric shock is lightning current shock; If there is a high-voltage AC transmission line near the installation area, the types of external strong electric shocks that are likely to occur are lightning current shocks and power frequency fault current shocks; If there is a DC converter station grounding electrode near the installation area, the most likely type of external strong electric shock to occur is a DC current shock.

4. The method for determining the parameters of an insulating device protector according to claim 2, characterized in that: The multiple impact parameters include: lightning current impact parameters, power frequency fault current impact parameters, direct current impact parameters and external impact parameters suffered by the insulation device.

5. The method for determining the parameters of an insulating device protector according to claim 3, characterized in that: The lightning current impulse parameter is calculated as follows: Obtain the lightning current I reaching the metal structure connected to the insulation device C , calculate the voltage E to the remote ground where the lightning current flows into the metal structure T : E T =I C ·Z C Among them, Z C The impedance of the metal path from the point where the lightning current strikes the surface of the structure to the insulating device; Based on the impulse lightning current I reaching the metal structure connected to the insulation device C , and the voltage to the ground at the point where the lightning current flows into the metal structure E T , calculate the lightning current I reaching the joint of the insulating device I : Among them, γ represents the attenuation constant of the metal structure, R G represents the characteristic impedance of the metal structure, x1 is the transmission distance between the lightning current flowing into the structure and reaching the joint of the insulation device; If the metal structure is buried, the characteristic impedance R G for: ρ is the resistance per unit length, g is the conductance per unit length; If the metal structure is installed on the ground, R G =ρ; The metal structure attenuation constant γ is: γ=(ρ·g) 0.5 The lightning current I reaching the joint of the insulation device I for: h represents the distance from the grounding electrode to the pipeline; The impedance Z of the metal path from the point where the lightning current strikes the surface of the structure to the insulating device C for: Z C =R G ·cosh(γ·x1) Lightning current I reaching the joint of the insulating device I That is the lightning current impulse parameter.

6. The method for determining the parameters of an insulating device protector according to claim 3, characterized in that: The lightning current impulse parameter is calculated by: obtaining lightning current impulse parameters through the second lightning current impulse insulation device; The second lightning current impulse insulation device includes a transmission line tower or a substation grounding electrode that is close to the pipeline. When the lightning current hits the tower or the ground wire on the tower, the lightning current flows to the buried grounding electrode through the tower or the down conductor; The grounding system discharges the lightning current I to the soil F , coupled with the adjacent pipeline, the fault current is injected at point A of the pipeline, and the injected fault current is distributed to the upstream and downstream of the pipeline at point A. The current from the injection point to the upstream is I U and the current distributed downstream from the injection point and I D Then the lightning current flows along the pipeline to the nearest insulation device upstream and downstream of the pipeline respectively. The upstream current reaches point B of insulation device i, and the downstream current reaches point C of insulation device j. The currents of the lightning current reaching points B and C are I Ci and I Cj , which are the lightning current impulse parameters received by the upstream and downstream insulation devices respectively; Among them, the impulse lightning current I reaching the pipeline injection point A I for: Z S is the soil resistance between the grounding system and the pipeline injection point A; ρ s represents the soil resistivity between the grounding system and the pipeline injection point A, and d represents the distance between the grounding system and the pipeline injection point A; The current upstream of the injection point is I U and the current I distributed downstream from the injection point D for: Z D is the pipeline impedance of the path from pipeline injection point A to insulation device j, Z U is the pipeline impedance of the path from pipeline injection point A to insulation device i; Z U =R G ·cosh(γ·x2) Where γ represents the pipeline attenuation constant, and x represents the transmission distance between the injection point A and the insulation device i; Z D =R G ·cosh(γ·y) y represents the distance between injection point A and insulating device j; Voltage U at pipeline injection point A A for: Lightning current I reaching the insulating device i Ci for: R G is the characteristic impedance of the pipeline, h represents the distance from the grounding electrode to the pipeline; The lightning current I reaching the insulating device i after sorting Ci for: Lightning current I reaching the insulating device j Cj for: The lightning current I reaching the insulating device j after sorting Cj for: Among them, the characteristic impedance R G for: ρ is the resistance per unit length, g is the conductance per unit length; The decay constant γ is: γ=(ρ·g) 0.5 。 7. The method for determining the parameters of an insulating device protector according to claim 6, characterized in that: The power frequency fault current impulse parameter is calculated in the same way as the lightning current impulse parameter.

8. The method for determining the parameters of an insulating device protector according to claim 2, characterized in that: The DC current impact parameter is calculated as follows: The point on the pipeline closest to the DC grounding electrode is marked as point A, d li The distance from point A is L i The unit length of the pipe section, V D The pipeline segment d is the closest to the DC grounding electrode. l1 The voltage on i The distance from the DC grounding electrode is r i The unit length of the pipe segment d li The voltage of i1 is the unit length pipeline section d closest to the DC grounding electrode. li The current flowing radially along the pipeline toward the insulating device; Measure the earth potential rise of the soil outside the pipeline coating and obtain the distance L from point A. i Unit length of pipe segment d li At, pipe section d li The ground potential rise of the soil outside the coating is U i : ρ is the average resistivity, I g is the current discharged from the DC grounding electrode to the earth, r i The unit length of the pipe segment is d li Distance from DC grounding electrode; The distance from the DC grounding electrode is r i The unit length of the pipe segment d li The voltage V i for: Z Pi The distance from point A is L i Pipe segment d li Unit length of pipeline section d li The grounding resistance, Z Ci The distance from point A is L i The unit length of the pipe segment d li The coating resistance; The current I flowing to the insulation device at a certain unit length of pipeline section i for: The current I flowing to the insulation device at a certain unit length of the pipeline after sorting i for: The insulation device is subject to the unit length of the pipeline section d li The current I Li for: γ represents the attenuation constant of the pipeline, and L represents the length from point A to the insulating device; When the pipe section from point A to the insulating device with a length of L is impacted by the DC grounding electrode into the ground current, the DC current impact parameters received by the insulating device are: i represents the total number of pipeline sections with a length of L from point A to the insulating device; Characteristic impedance R G for: ρ is the resistance per unit length, g is the conductance per unit length; The decay constant γ is: γ=(ρ·g) 0.5 The insulation device is subject to the unit length of the pipeline section d li The current I Li That is the DC current impact parameter.

9. The method for determining the parameters of an insulating device protector according to claim 1, characterized in that: The step S3 is: For the current value of the insulating device protector, the current value constraint conditions must be met: The calculated current value is less than the measured current value at which the insulation device is damaged and less than the minimum current value that the insulation device protector should have; For the voltage value of the insulation device protector, the voltage value constraint conditions must be met: The measured voltage value at which the insulation device is damaged > the calculated voltage value > the maximum voltage threshold that the insulation device protector should have.

Images