Method and system for suppressing lightning stroke overvoltage of GIL-overhead line series-parallel transmission line

Abstract

The invention discloses a method and a system for suppressing lightning stroke overvoltage of a GIL-overhead line series-parallel transmission line. The method comprises the following steps: acquiring operation parameters and electrical parameters of a GIL and an overhead transmission line; building an equivalent circuit of the series-parallel power transmission line; simulating and calculating the amplitude of the lightning stroke overvoltage of the hybrid power transmission line when the lightning stroke fault occurs; wherein the types of the lightning stroke faults comprise lightning counterattack and lightning shielding failure; a lightning arrester model and an arrangement mode are selected, and a series-parallel power transmission line lightning stroke overvoltage suppression design scheme is generated; verifying whether the maximum lightning stroke overvoltage on the hybrid power transmission line is lower than an allowable value after the simulation execution of the design scheme, and if the maximum lightning stroke overvoltage is lower than the allowable value, determining that the design scheme is feasible; and if the maximum lightning stroke overvoltage is higher than the allowable value, regenerating the design scheme. The lightning stroke overvoltage suppression effect on the GIL-overhead line series-parallel transmission line is more obvious, the lightning stroke overvoltage suppression effect and the cost of the design scheme are both considered, and a guarantee is provided for stable operation of the series-parallel transmission line.

Description

Technical Field

[0001] The present invention belongs to the technical field of lightning overvoltage suppression, and more specifically, relates to a method and system for suppressing lightning overvoltage of a GIL-overhead line hybrid transmission line. Background Art

[0002] With the development of the power system, a new way of constructing transmission lines has been to transform overhead transmission lines into GIL-overhead line hybrid transmission lines by connecting them to GIL (Gas Insulated Transmission Lines) equipment. Since GIL is usually laid in underground pipe corridors, it is rarely directly affected by direct lightning strikes. However, when an overhead transmission line is struck by lightning, the lightning wave will be transmitted to the GIL along the overhead line, which is called a lightning intrusion wave. The lightning intrusion wave will cause obvious lightning overvoltage in the GIL and cause problems such as insulation aging.

[0003] At present, hybrid transmission line projects still use the same lightning overvoltage suppression method as single transmission lines. Due to the differences in overvoltage characteristics between hybrid transmission lines and overhead transmission lines or gas insulated transmission lines, the original overvoltage suppression method may not be applicable to hybrid transmission lines. The prior art lacks a lightning overvoltage suppression method for GIL-overhead line hybrid transmission lines. Therefore, a method for suppressing lightning overvoltage for GIL-overhead line hybrid transmission lines is needed. Summary of the invention

[0004] In order to solve the deficiencies in the prior art, the present invention provides a method for suppressing lightning overvoltage of a GIL-overhead line hybrid transmission line. According to the actual situation of the hybrid transmission line, the lightning overvoltage amplitude of the hybrid transmission line is obtained, and an appropriate lightning overvoltage suppression strategy is adopted to provide guarantee for the stable operation of the hybrid transmission line.

[0005] The present invention adopts the following technical solution.

[0006] A first aspect of the present invention provides a method for suppressing lightning overvoltage of a GIL-overhead line hybrid transmission line, characterized in that it comprises the following steps:

[0007] Step 1, respectively obtaining the operating parameters and electrical parameters of the GIL and the overhead transmission line;

[0008] Step 2: construct an equivalent circuit of the hybrid transmission line according to the operating parameters and electrical parameters obtained in step 1;

[0009] Step 3, using the equivalent circuit simulation of step 2 to calculate the amplitude of the lightning overvoltage of the hybrid transmission line when a lightning fault occurs; wherein the types of lightning faults include lightning strike back and lightning shielding failure;

[0010] Step 4, according to the amplitude of the lightning overvoltage calculated in step 3, select the arrester model and layout method, and generate a design scheme for suppressing lightning overvoltage of the hybrid transmission line;

[0011] Step 5, verify whether the maximum lightning overvoltage on the hybrid transmission line is lower than the allowable value after simulating the design scheme of step 4. If the maximum lightning overvoltage is lower than the allowable value, the design scheme is feasible; if the maximum lightning overvoltage is higher than the allowable value, return to step 4 to regenerate the design scheme, where the maximum lightning overvoltage is the maximum value of the lightning overvoltages generated by all types of lightning faults.

[0012] Preferably, in step 1, the operating parameters include the voltage level of the hybrid transmission line, the rated current and frequency value of the transmission line.

[0013] Preferably, in step 1, the electrical parameters include capacitance, inductance and AC resistance values ​​of the GIL and the overhead transmission line.

[0014] Preferably, the electrical parameters of the GIL are obtained by finite element calculation, and the electrical parameters of the overhead transmission line are determined according to the actual model.

[0015] Preferably, in step 2, building an equivalent circuit of the hybrid transmission line includes: using an RLC equivalent circuit to build an equivalent circuit of the GIL; using a J.Marti equivalent circuit to build an equivalent circuit of the overhead transmission line.

[0016] Preferably, in step 3, when the type of lightning fault is lightning strike back, the amplitude of the lightning overvoltage is expressed by the following formula:

[0017]

[0018] Where:

[0019] β is the split coefficient;

[0020] i represents the current flowing through the fault point;

[0021] R i is the impulse grounding resistance of the tower;

[0022] L t is the inductance of the overhead transmission line tower.

[0023] Preferably, in step 3, when the type of lightning fault is lightning shielding failure, the amplitude of the lightning overvoltage is expressed by the following formula:

[0024]

[0025] Where:

[0026] I represents the initial input current;

[0027] Z0 represents the initial impedance;

[0028] Z is the wave impedance of the overhead transmission line conductor;

[0029] U ph·m It is the peak value of the working voltage on the overhead transmission line;

[0030] ω represents the angular frequency.

[0031] Preferably, in step 4, the lightning arrester arrangement includes: no lightning arrester is installed at both ends of the GIL, a lightning arrester is installed only at the end of the GIL, and a lightning arrester is installed at both ends of the GIL.

[0032] Preferably, in step 5, the allowable value is set to 1.5 to 2 times the rated voltage of the line. When the maximum lightning overvoltage is higher than the allowable value, additional lightning overvoltage suppression measures for hybrid transmission lines are added to the design scheme, including reducing the grounding resistance of the tower, installing lightning protection wires, and using arc suppression coil grounding methods.

[0033] A second aspect of the present invention provides a GIL-overhead line hybrid transmission line lightning overvoltage suppression system, and a method for suppressing lightning overvoltage of a GIL-overhead line hybrid transmission line includes:

[0034] A parameter acquisition module, used to obtain the operating parameters and electrical parameters of the GIL and overhead transmission line respectively;

[0035] Equivalent circuit module, used to build the equivalent circuit of the hybrid transmission line;

[0036] An overvoltage calculation module is used to simulate and calculate the amplitude of the lightning overvoltage of the hybrid transmission line when a lightning fault occurs;

[0037] A scheme generation module is used to generate a design scheme for lightning overvoltage suppression of hybrid transmission lines;

[0038] The overvoltage verification module is used to verify whether the maximum lightning overvoltage on the hybrid transmission line is lower than the allowable value. When the maximum lightning overvoltage is higher than the allowable value, it returns to the solution generation module to regenerate the design solution.

[0039] Compared with the prior art, the beneficial effects of the present invention include at least:

[0040] (1) The present invention aims at the lightning overvoltage characteristics of the hybrid line, fully considers the lightning strike and lightning shielding failure, and has a more obvious lightning overvoltage suppression effect on the GIL-overhead line hybrid transmission line, thereby maintaining the safety of the transmission line and the power system.

[0041] (2) The present invention selects and arranges lightning arresters according to the amplitude of lightning overvoltage, taking into account both the lightning overvoltage suppression effect and the cost of the design solution.

[0042] (3) The present invention verifies the feasibility of the design scheme by setting an allowable value, thereby ensuring the safety and reliability of the design scheme for suppressing lightning overvoltage of hybrid transmission lines. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is a flow chart of a method for suppressing lightning overvoltage of a GIL-overhead line hybrid transmission line provided in accordance with an embodiment of the present invention;

[0044] Figure 2 It is a hybrid power transmission line diagram provided according to an application example of the present invention;

[0045] Figure 3 It is an equivalent circuit diagram of a hybrid power transmission line provided according to an application example of the present invention;

[0046] Figure 4 It is a comparison diagram of lightning strike back overvoltage waveforms when lightning arresters are installed in different ways at both ends of a gas-insulated transmission line according to an application example of the present invention;

[0047] Figure 5 The present invention provides a comparison diagram of lightning shielding overvoltage waveforms when arresters are installed in different ways at both ends of a gas-insulated transmission line according to an application example of the present invention. DETAILED DESCRIPTION

[0048] In order to make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The embodiments described in this application are only part of the embodiments of the present invention, not all of them. Based on the spirit of the present invention, other embodiments obtained by ordinary technicians in this field without creative work are all within the scope of protection of the present invention.

[0049] like Figure 1 As shown, embodiment 1 of the present invention provides a method for suppressing lightning overvoltage of a GIL-overhead line hybrid transmission line, comprising the following steps:

[0050] Step 1: Obtain basic operating parameters and basic electrical parameters of the GIL and overhead transmission line respectively.

[0051] Preferably, the basic operating parameters include the voltage level of the hybrid transmission line, the rated current and frequency value of the transmission line, etc.

[0052] Preferably, the basic electrical parameters include capacitance, inductance and AC resistance values ​​of the GIL and the overhead transmission line;

[0053] Further preferably, the basic electrical parameter values ​​of the GIL can be obtained through finite element calculation, and the basic electrical parameter values ​​of the overhead transmission line can be determined according to the actual model.

[0054] Step 2: Based on the operating parameters and electrical parameters obtained in step 1 and in combination with the actual project conditions, an equivalent circuit of the corresponding hybrid transmission line is constructed.

[0055] Preferably, when constructing the equivalent circuit of the gas-insulated transmission line, an RLC equivalent circuit is used, and the electromagnetic induction between different phases is considered. When constructing the equivalent circuit of the overhead transmission line, a J.Marti equivalent circuit is used to simulate the high-frequency component of lightning strikes.

[0056] Step 3, using the equivalent circuit simulation of step 2 to calculate the amplitude of the lightning overvoltage of the hybrid transmission line when a lightning fault occurs;

[0057] Among them, the types of lightning faults include lightning counter-strike and lightning shielding failure. The determined lightning overvoltage needs to take into account the overvoltage conditions of all types of lightning faults.

[0058] Preferably, for the case of lightning strike back, the amplitude of the GIL lightning overvoltage caused by the lightning intrusion wave generated at the lightning fault point is expressed by the following formula:

[0059]

[0060] Where:

[0061] β is the split coefficient;

[0062] L t is the inductance of the overhead transmission line tower;

[0063] R i is the impulse grounding resistance of the tower;

[0064] i represents the current flowing through the fault point;

[0065] i1 represents the initial current;

[0066] L I represents the coil inductance;

[0067] i t Represents the line tower current.

[0068] Further preferably, for the case of lightning shielding failure, the amplitude of the GIL lightning overvoltage caused by the lightning intrusion wave generated at the lightning fault point is expressed by the following formula:

[0069]

[0070] Where:

[0071] I represents the initial input current;

[0072] Z0 represents the initial impedance;

[0073] Z is the wave impedance of the overhead transmission line conductor;

[0074] U ph·m It is the peak value of the working voltage on the overhead transmission line;

[0075] ω represents the angular frequency.

[0076] It can be understood that the present invention takes into account the different lightning strike conditions and overvoltage characteristics of hybrid transmission lines and traditional single overhead transmission lines, and specifically calculates the GIL lightning overvoltage caused by the lightning intrusion wave. On this basis, the overvoltage suppression scheme for the hybrid transmission line is designed, and the suppression effect of the lightning overvoltage of the hybrid transmission line is more obvious.

[0077] Step 4: According to the amplitude of the lightning overvoltage calculated in step 3, the arrester model and arrangement are selected to generate a design scheme for suppressing lightning overvoltage of the hybrid transmission line.

[0078] Specifically, appropriate lightning arrester models are selected according to actual conditions and installed at both ends of the hybrid transmission line. To further suppress the lightning overvoltage in the GIL section of the hybrid transmission line, appropriate lightning arrester arrangements are selected at both ends of the gas insulated transmission line according to the lightning overvoltage amplitude of the line.

[0079] Taking the 220kV voltage level GIL as an example, the arrester models include 110kV and 220kV. When the amplitude of the lightning overvoltage is greater than 300kV, the 220kV model of the arrester is selected because its higher withstand voltage can effectively suppress high-amplitude overvoltages. When the amplitude of the lightning overvoltage is between 200kV and 300kV, the 110kV model of the arrester is selected to optimize the cost while ensuring the suppression effect.

[0080] It is understandable that according to different lightning overvoltage amplitudes, selecting the most suitable lightning arrester model can achieve the best overvoltage suppression effect while taking into account economy.

[0081] Preferably, in order to reduce the actual engineering workload, the lightning arrester arrangements adopted at both ends of the GIL include: no lightning arrester is installed at both ends of the GIL, lightning arrester is installed only at the end of the GIL, and lightning arrester is installed at both ends of the GIL.

[0082] Taking the 220kV GIL as an example, when the lightning overvoltage amplitude is greater than 300kV, the arrangement method of not installing lightning arresters at both ends of the GIL is selected, because the overvoltage amplitude is too high at this time and it can no longer be suppressed by installing lightning arresters, and other supplementary suppression measures are required; when the lightning overvoltage amplitude is between 200kV and 300kV, the arrangement method of installing lightning arresters only at the end of the GIL is selected to provide key protection at the end.

[0083] Step 5, verify whether the maximum lightning overvoltage on the hybrid transmission line is lower than the allowable value after the design scheme of step 4 is simulated. If the maximum lightning overvoltage is lower than the allowable value, the design scheme is feasible; if the maximum lightning overvoltage is higher than the allowable value, return to step 4 to regenerate the design scheme. The maximum lightning overvoltage is the maximum value of the lightning overvoltage amplitude waveforms generated by all types of lightning faults calculated in step 3.

[0084] Preferably, according to the withstand voltage value of the transmission line specified in the national or industry standards, and taking into account the safety margin and line insulation level in the actual project, the allowable value is set to 1.5 to 2 times the rated voltage of the line to ensure sufficient safety margin. For example, for a line with a rated voltage of 220kV, the allowable value can be set to 330kV to 440kV to ensure the safety of the line in actual operation while avoiding unnecessary over-design and cost increase.

[0085] Preferably, when the maximum lightning overvoltage is higher than the allowable value, when the design scheme is regenerated, other lightning overvoltage supplementary suppression measures such as reducing the grounding resistance of the tower, erecting lightning protection wires, and adopting arc suppression coil grounding methods can be taken for the hybrid transmission lines.

[0086] Embodiment 2 of the present invention provides a system for suppressing lightning overvoltage of a GIL-overhead line hybrid transmission line, and operates a method for suppressing lightning overvoltage of a GIL-overhead line hybrid transmission line as described in Embodiment 1, including: a parameter acquisition module, an equivalent circuit module, an overvoltage calculation module, a scheme generation module, and an overvoltage verification module.

[0087] Among them, the parameter acquisition module is used to obtain the operating parameters and electrical parameters of the GIL and overhead transmission line respectively;

[0088] The equivalent circuit module is used to build the equivalent circuit of the hybrid transmission line;

[0089] The overvoltage calculation module is used to simulate and calculate the amplitude of the lightning overvoltage of the hybrid transmission line when a lightning fault occurs;

[0090] The scheme generation module is used to generate a design scheme for lightning overvoltage suppression of hybrid transmission lines;

[0091] The overvoltage verification module is used to verify whether the maximum lightning overvoltage on the hybrid transmission line is lower than the allowable value. When the maximum lightning overvoltage is higher than the allowable value, it returns to the solution generation module to regenerate the design solution.

[0092] In an application example of the present invention, Figure 2 It is a typical structure of GIL-overhead line hybrid transmission line. The substation end 1 is connected to the overhead transmission line section I, the GIL head end is connected to the overhead transmission line section I, and the end end is connected to the overhead transmission line section II. The overhead transmission line section II is connected to the three-phase common box GIL and the substation end 2.

[0093] The method for suppressing lightning overvoltage of a GIL-overhead line hybrid transmission line described in Example 1 is used to perform overvoltage analysis, arrester selection and installation method selection on the hybrid transmission line. The equivalent circuit diagram of the hybrid transmission line obtained is as follows: Figure 3 As shown in the figure, it includes overhead transmission lines, gas-insulated transmission lines and their grounding systems; the lightning strike back overvoltage waveform comparison when lightning arresters are installed in different ways at both ends of the gas-insulated transmission line is shown in the figure. Figure 4 Comparison of lightning shielding overvoltage waveforms when using different methods to set up lightning arresters Figure 5 , where 1 means there is no arrester at both ends, 2 means arresters are installed at the ends, and 3 means arresters are installed at both ends.

[0094] As can be seen from the figure, the method of installing lightning arresters at both ends has the best effect in suppressing lightning overvoltage. However, in reality, considering the actual engineering volume and economic conditions, the final method of installing lightning arresters at the ends that meets the requirement that the maximum lightning overvoltage is lower than the allowable value can be selected.

[0095] Compared with the prior art, the beneficial effects of the present invention include at least:

[0096] (1) The present invention aims at the lightning overvoltage characteristics of the hybrid line, fully considers the lightning strike and lightning shielding failure, and has a more obvious lightning overvoltage suppression effect on the GIL-overhead line hybrid transmission line, thereby maintaining the safety of the transmission line and the power system.

[0097] (2) The present invention selects and arranges lightning arresters according to the amplitude of lightning overvoltage, taking into account both the lightning overvoltage suppression effect and the cost of the design solution.

[0098] (3) The present invention verifies the feasibility of the design scheme by setting an allowable value, thereby ensuring the safety and reliability of the design scheme for suppressing lightning overvoltage of hybrid transmission lines.

[0099] The present disclosure may be a system, a method and / or a computer program product. The computer program product may include a computer-readable storage medium carrying computer-readable program instructions for causing a processor to implement various aspects of the present disclosure.

[0100] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents, and any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for suppressing lightning overvoltage in a GIL-overhead line hybrid transmission line, characterized in that: The following steps are involved: Step 1, respectively obtaining the operating parameters and electrical parameters of the GIL and the overhead transmission line; Step 2: construct an equivalent circuit of the hybrid transmission line according to the operating parameters and electrical parameters obtained in step 1; Step 3, using the equivalent circuit simulation of step 2 to calculate the amplitude of the lightning overvoltage of the hybrid transmission line when a lightning fault occurs; wherein the types of lightning faults include lightning strike back and lightning shielding failure; Step 4, according to the amplitude of the lightning overvoltage calculated in step 3, select the arrester model and layout method, and generate a design scheme for suppressing lightning overvoltage of the hybrid transmission line; Step 5, verify whether the maximum lightning overvoltage on the hybrid transmission line is lower than the allowable value after simulating the design scheme of step 4. If the maximum lightning overvoltage is lower than the allowable value, the design scheme is feasible; if the maximum lightning overvoltage is higher than the allowable value, return to step 4 to regenerate the design scheme, where the maximum lightning overvoltage is the maximum value of the lightning overvoltages generated by all types of lightning faults.

2. The method for suppressing lightning overvoltage in a GIL-overhead line hybrid transmission line according to claim 1, characterized in that: In step 1, the operating parameters include the voltage level of the hybrid transmission line, the rated current and frequency value of the transmission line.

3. The method for suppressing lightning overvoltage in a GIL-overhead line hybrid transmission line according to claim 1, characterized in that: In step 1, the electrical parameters include capacitance, inductance and AC resistance values ​​of the GIL and the overhead transmission line.

4. The method for suppressing lightning overvoltage of a GIL-overhead line hybrid transmission line according to claim 3 is characterized in that: The electrical parameters of the GIL are obtained through finite element calculation, and the electrical parameters of the overhead transmission line are determined according to the actual model.

5. The method for suppressing lightning overvoltage in a GIL-overhead line hybrid transmission line according to claim 1, characterized in that: In step 2, building an equivalent circuit of the hybrid transmission line includes: using an RLC equivalent circuit to build an equivalent circuit of the GIL; using a J.Marti equivalent circuit to build an equivalent circuit of the overhead transmission line.

6. The method for suppressing lightning overvoltage in a GIL-overhead line hybrid transmission line according to claim 1, characterized in that: In step 3, when the type of lightning fault is lightning strike back, the amplitude of the lightning overvoltage is expressed by the following formula: Where: β is the split coefficient; i represents the current flowing through the fault point; R i is the impulse grounding resistance of the tower; L t is the inductance of the overhead transmission line tower.

7. The method for suppressing lightning overvoltage in a GIL-overhead line hybrid transmission line according to claim 1, characterized in that: In step 3, when the type of lightning fault is lightning shielding failure, the amplitude of the lightning overvoltage is expressed by the following formula: Where: I represents the initial input current; Z0 represents the initial impedance; Z is the wave impedance of the overhead transmission line conductor; U ph·m It is the peak value of the working voltage on the overhead transmission line; ω represents the angular frequency.

8. The method for suppressing lightning overvoltage in a GIL-overhead line hybrid transmission line according to claim 1, characterized in that: In step 4, the lightning arrester arrangement methods include: no lightning arrester is installed at both ends of the GIL, lightning arrester is installed only at the end of the GIL, and lightning arrester is installed at both ends of the GIL.

9. The method for suppressing lightning overvoltage in a GIL-overhead line hybrid transmission line according to claim 1, characterized in that: In step 5, the allowable value is set to 1.5 to 2 times the rated voltage of the line. When the maximum lightning overvoltage is higher than the allowable value, additional lightning overvoltage suppression measures for hybrid transmission lines are added to the design plan, including reducing the grounding resistance of the tower, installing lightning protection wires, and using arc suppression coil grounding methods.

10. A system for suppressing lightning overvoltage of a GIL-overhead line hybrid transmission line, which operates the method for suppressing lightning overvoltage of a GIL-overhead line hybrid transmission line as claimed in any one of claims 1 to 9, characterized in that: include: A parameter acquisition module, used to obtain the operating parameters and electrical parameters of the GIL and overhead transmission line respectively; Equivalent circuit module, used to build the equivalent circuit of the hybrid transmission line; An overvoltage calculation module is used to simulate and calculate the amplitude of the lightning overvoltage of the hybrid transmission line when a lightning fault occurs; A scheme generation module is used to generate a design scheme for lightning overvoltage suppression of hybrid transmission lines; The overvoltage verification module is used to verify whether the maximum lightning overvoltage on the hybrid transmission line is lower than the allowable value. When the maximum lightning overvoltage is higher than the allowable value, it returns to the solution generation module to regenerate the design solution.

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