CN110765666A - Simulation method for indirect breakdown fault of power transmission line caused by lightning stroke due to bifurcated lightning - Google Patents
Simulation method for indirect breakdown fault of power transmission line caused by lightning stroke due to bifurcated lightning Download PDFInfo
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Abstract
The invention discloses a method for simulating an indirect breakdown fault of a power transmission line caused by lightning stroke by a bifurcated lightning, which comprises the following steps: establishing a power transmission line model: the power transmission line is powered by a transmitting-end transformer substation, electric energy is transmitted to a receiving-end transformer substation through the power transmission line, and the power transmission line is erected by a tower every hundreds of meters; establishing a lightning channel model: the R-C branch is used for equivalent the discharging process of the lightning pilot channel to the ground; establishing a simulation model: and simulating the process of indirect breakdown caused by the bifurcation lightning of the real power transmission line. The method can quantitatively calculate the amplitude of the discharge pulse generated on the power transmission line by the bifurcated lightning, can assist in judging the fault property in actual operation, effectively prevents the fault of indirect breakdown of the power transmission line caused by the bifurcated lightning, and avoids the hidden trouble generated on the line under the condition of indirect breakdown of the bifurcated lightning.
Description
Technical Field
The invention relates to a method for simulating an indirect breakdown fault of a power transmission line caused by a lightning stroke of a bifurcated lightning, and belongs to the technical field of lightning protection of power transmission lines.
Background
The lightning current can generate strong electromagnetic field, thermal effect and stress action, and has adverse effect on the power transmission line and electrical equipment. Due to the complexity of the lightning process and various reasons causing lightning accidents, in order to master the lightning characteristics and accurately analyze the lightning development process, a large number of lightning positioning systems, lightning currents and lightning overvoltage monitoring systems are adopted to record fault waveforms at present, and lightning stroke fault finding and identification are assisted.
A large amount of theoretical researches are conducted on lightning overvoltage at home and abroad, a large amount of lightning overvoltage simulation models are established, influences of lightning impact on ultrahigh-speed transient protection and lightning resistance performance are analyzed based on simulation, and characteristics of short-circuit faults are identified and researched. In the last 80 th century, the power grid of China began to research lightning monitoring technology, develop and build lightning positioning systems, and at present, power grid lightning monitoring networks have been built nationwide, so that a reliable platform is provided for quick positioning of lightning faults, identification of lightning accidents, statistics of lightning parameters, assessment of lightning protection level and lightning early warning. In recent years, induced overvoltage and counterattack overvoltage generated by lightning pole tower tops are calculated and analyzed by an electromagnetic field theory, and the basis of lightning protection calculation and lightning protection design is supplemented. In order to deeply research the nature of line lightning stroke accidents, the automatic identification and diagnosis system is researched to automatically identify and diagnose the type of lightning stroke overvoltage by combining with the monitoring data provided by the online monitoring system, and measures for quickly responding and inhibiting the overvoltage are taken according to the diagnosis result.
In actual operation, the lightning points of the power transmission line cannot be completely concentrated on the conducting wire, the lightning conductor and the tower, so that the lightning stroke research has complexity and uncertainty. At present, most of the existing researches aim at the lightning stroke of direct breakdown, and few researches specially aim at indirect breakdown. The two breakdown modes have different influences on the power system, hidden dangers can be generated on the line under the condition of indirect breakdown, but the probability of causing line tripping is smaller than that of direct breakdown. Indirect breakdown is also distinguished from direct breakdown in terms of lightning strike fault characteristics.
When the bifurcated lightning is a lightning strike ground, due to the randomness of discharge of the long air gap, a plurality of branch leaders can simultaneously appear in several directions with similar electric field intensity in the descending development process of the lightning leader, and the lightning leader simultaneously hits a plurality of ground objects. Due to the particularity of the bifurcated lightning, at present, the research on the lightning stroke fault of the bifurcated lightning is lacked, so that a simulation method for the lightning stroke indirect breakdown fault of the power transmission line caused by the bifurcated lightning is required to be provided.
Disclosure of Invention
Aiming at the defects of the existing research, the invention provides a method for simulating the lightning stroke indirect breakdown fault of the power transmission line caused by the bifurcated lightning, which can effectively judge the lightning stroke indirect breakdown fault of the power transmission line caused by the bifurcated lightning.
The technical scheme adopted for solving the technical problems is as follows:
the embodiment of the invention provides a method for simulating an indirect breakdown fault of a power transmission line caused by lightning stroke by a bifurcated lightning, which comprises the following steps:
establishing a power transmission line model: the power transmission line is powered by a transmitting-end transformer substation, electric energy is transmitted to a receiving-end transformer substation through the power transmission line, and the power transmission line is erected by a tower every hundreds of meters;
establishing a lightning channel model: the R-C branch is used for equivalent the discharging process of the lightning pilot channel to the ground;
establishing a simulation model: and simulating the process of indirect breakdown caused by the bifurcation lightning of the real power transmission line.
As a possible implementation manner of this embodiment, the transmission line model includes transmission line geometric dimensions and conductor data.
As a possible implementation manner of this embodiment, the lightning channel model is that when the lightning leader moves downwards along the channel, the electrical charge is stored in the channel, which is equivalent to that there is energy storage on the energy storage element capacitor in the circuit, when the streamer of the lightning leader corona reaches the ground, the last step of the discharge starts, and when the strike back progresses upwards, the electrical charge in the channel discharges to the ground, which is equivalent to that the energy stored at the moment of changing the path is discharged in the form of thermal energy through the resistor in the circuit.
As a possible implementation of this embodiment, in the lightning path model, the lightning conductor voltage u is estimated by the following formula:
wherein i is the lightning current and Z is the wave impedance of the lightning channel.
As a possible implementation manner of the embodiment, a simulation model is established based on ATP-EMTP.
As a possible implementation manner of this embodiment, a power transmission line model is established by using a j.marti model.
As a possible implementation manner of this embodiment, the simulation model does not relate to a tower.
As a possible implementation manner of this embodiment, the transmission line does not consider the relay station.
The technical scheme of the embodiment of the invention has the following beneficial effects:
the technical scheme of the embodiment of the invention can quantitatively calculate the amplitude of the discharge pulse generated on the power transmission line by the bifurcated lightning, can assist in judging the fault property in actual operation, can prevent the fault of indirect breakdown of the power transmission line caused by the bifurcated lightning, and avoids the hidden danger generated on the line under the condition of indirect breakdown of the bifurcated lightning.
Description of the drawings:
FIG. 1 is a flow diagram illustrating a method for simulating a power transmission line lightning strike indirect breakdown fault caused by a bifurcated lightning strike in accordance with an exemplary embodiment;
FIG. 2 is a schematic illustration of a bifurcated lightning discharge process;
FIG. 3 is an equivalent circuit diagram of a lightning path;
FIG. 4 is a schematic diagram of a simulation model of indirect breakdown of a power transmission line caused by a bifurcated lightning;
FIG. 5 is a schematic diagram of the geometry of a double circuit line on the same tower;
FIG. 6 is a schematic diagram of a failed phase B-phase current;
FIG. 7 is a schematic of three phase currents at a fault time;
fig. 8 is a schematic diagram of three phase voltages at a fault time.
Detailed Description
The invention is further illustrated by the following examples in conjunction with the accompanying drawings:
in order to clearly explain the technical features of the present invention, the following detailed description of the present invention is provided with reference to the accompanying drawings. The following disclosure provides many different embodiments, or examples, for implementing different features of the invention. To simplify the disclosure of the present invention, the components and arrangements of specific examples are described below. Furthermore, the present invention may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. It should be noted that the components illustrated in the figures are not necessarily drawn to scale. Descriptions of well-known components and processing techniques and procedures are omitted so as to not unnecessarily limit the invention.
FIG. 1 is a flow chart illustrating a method for simulating a lightning strike indirect breakdown fault of a transmission line caused by a bifurcated lightning strike according to an exemplary embodiment. As shown in fig. 1, the simulation method for the power transmission line lightning strike indirect breakdown fault caused by the bifurcated lightning provided by the embodiment of the invention includes the following steps:
establishing a power transmission line model: the power transmission line is powered by a transmitting-end transformer substation, electric energy is transmitted to a receiving-end transformer substation through the power transmission line, and the power transmission line is erected by a tower every hundreds of meters;
establishing a lightning channel model: the R-C branch is used for equivalent the discharging process of the lightning pilot channel to the ground;
establishing a simulation model: and simulating the process of indirect breakdown caused by the bifurcation lightning of the real power transmission line.
The invention can quantitatively calculate the amplitude of the discharge pulse generated on the transmission line by the bifurcated mine and can assist in judging the fault property in actual operation.
1. The branch mine causes the indirect breakdown of the transmission line
When the bifurcated lightning strikes the ground, the lightning current is bifurcated due to the particularity of the accumulated charges near the ground, so that two discharge points are formed on the ground. As shown in fig. 2.
As shown in figure 2, the lightning leader generates a plurality of branches in the process of descending to approach the ground, wherein one branch I of the lightning leader hits a certain phase of the line, the other branch II of the lightning leader hits the ground, and a power frequency discharge channel of the lightning leader to the ground is formed between the two branches. However, the arc discharge channel is longer and the arc resistance is higher, so that a stable power frequency arc cannot be formed, and the discharge channel is extinguished. The short-time discharge pulse formed on the line conductor in the process causes the tripping of the current differential protection action due to large differential current on two sides. After the lightning strike, the corresponding lightning channel is not formed inside temporarily, and the insulator is not broken down, so the insulator is indirectly broken down.
When the line is indirectly broken down due to the bifurcated lightning, the lightning current is generally smaller than the lightning strike resistance level of the line, and the power frequency follow current channel is unstable and easy to extinguish, so that no obvious discharge trace exists on the line.
2. Establishment of simulation model
The method is used for establishing a simulation model based on ATP-EMTP and simulating the process of indirect breakdown caused by the bifurcated lightning of the real power transmission line. Because the fault current does not pass through the tower, the tower is not involved in the model. And a time control switch is adopted for fault triggering.
The real transmission line structure is as follows: the transmission line is powered by a transmitting-end substation, electric energy is transmitted to a receiving-end substation through the transmission line, and the transmission line is erected by towers every hundreds of meters. In practice, to reduce the power loss, a transfer station is constructed. The model does not consider a transfer substation, and comprises a sending end power supply model, a power transmission line model and a lightning stroke channel model.
(1) Transmission line model
The simulation requires detailed transmission line geometry and conductor data. In electromagnetic transient calculations, changes in line parameters with frequency affect the electromagnetic transient process. The Marti line equivalent model is relatively stable in transient calculation, and the calculation accuracy deviation is relatively small when the main frequencies such as ground faults are intensively calculated, so that the line model selects the J.Marti line equivalent model.
(2) Lightning channel model
When the pilot moves downwards along the channel, the charge is stored in the channel, which is equivalent to the energy storage element in the circuit which has energy stored on the capacitor, and when the current of the pilot corona reaches the ground, the last step of discharge starts. When the back-strike is developed upwards, the charge in the channel is discharged to the ground, which is equivalent to the energy stored at the moment of switching, and the energy is discharged in the form of heat energy through a resistor in the circuit. Therefore, the R-C branch can be used to equivalent the discharging process of the pilot channel to the ground, as shown in FIG. 3.
The voltage of the capacitor C is the voltage of the wire when the wire is struck by lightning, and the voltage of the wire when the wire is struck by lightning can be estimated by the following formula:
wherein i is the lightning current and Z is the wave impedance of the lightning channel.
According to the regulations of GB/T50064-2014 'design specifications for overvoltage protection and insulation matching of alternating current electrical devices', when the lightning current is less than 20kA, the wave impedance of the lightning channel is greater than 1000 ohms, and when the lightning current is between 20 and 40kA, the wave impedance of the lightning channel is about 600-1000 ohms.
(3) Simulation model
The simulation model is shown in fig. 4, where LCC is a line element, U1 and U2 are line terminal power supplies, LINEZ-T is ABC three-phase wire impedance, LINEZ is ground line impedance, U (0) is a charging capacitor, R is lightning channel impedance, G is a time control switch, I is a current detector, and V is a voltage detector.
Detailed description of the preferred embodiments
By taking a 1000kV power transmission line and lightning striking on a B-phase conductor as an example, the bifurcated lightning current is 30 kA. The lightning shielding failure resistant level of the 1000kV line is about 40kA, and the line shielding failure tripping is not caused.
(1) Line parameters
The same-tower double-circuit transmission line is characterized in that the conductor is arranged as shown in figure 5, the conductor adopts 8 XJL 1/LHA1-465/210, the ground wire adopts OPGW-185, the radius of the sub-conductor is calculated to be 210mm, the sub-conductor is eight-split, the split distance is 400mm, the height of the sub-conductor to the ground is 84m, and all phases are horizontally arranged.
(2) Lightning channel parameters
The lightning current is 30kA, the wave impedance of a lightning channel is 800 ohms, and the initial voltage of the capacitor C is 6000 kV.
(3) The power supply is a 1000kV alternating current power supply.
(4) The voltage and current waveforms of the conductor at the time of the lightning stroke B-phase short circuit are shown in FIGS. 6 to 8.
The phase B current of the fault phase is rapidly increased at the moment of lightning short circuit, the amplitude is 4.5kA, and the phase B current is recovered after about 1 ms. The AC phase current fluctuates slightly due to electromagnetic induction and recovers after about 1 ms. The three-phase voltage fluctuates due to the short circuit of the B phase, and is recovered after about 1 ms. 4.5kA short-time discharge pulse on a line conductor can cause the tripping of protection action, the fault disappears after 1ms, and the line reclosing is successful.
The foregoing is only a preferred embodiment of the present invention, and it will be apparent to those skilled in the art that various modifications and improvements can be made without departing from the principle of the present invention, and these modifications and improvements are also considered to be within the scope of the present invention.
Claims (8)
1. A method for simulating a lightning stroke indirect breakdown fault of a power transmission line caused by a bifurcated lightning is characterized by comprising the following steps:
establishing a power transmission line model: the power transmission line is powered by a transmitting-end transformer substation, electric energy is transmitted to a receiving-end transformer substation through the power transmission line, and the power transmission line is erected by a tower every hundreds of meters;
establishing a lightning channel model: the R-C branch is used for equivalent the discharging process of the lightning pilot channel to the ground;
establishing a simulation model: and simulating the process of indirect breakdown caused by the bifurcation lightning of the real power transmission line.
2. The method of claim 1, wherein the power transmission line model comprises transmission line geometry and conductor data.
3. The method of claim 1, wherein the lightning channel model is that when the lightning leader moves downwards along the channel, the lightning channel model stores charges in the channel, which is equivalent to energy storage in an energy storage element capacitor in the circuit, when the corona current of the lightning leader reaches the ground, the last step of discharge starts, and when the strike back progresses upwards, the charges in the channel discharge to the ground is equivalent to the energy stored at the moment of changing the circuit and is discharged in the form of heat energy through a resistor in the circuit.
4. The method of claim 1, wherein in the lightning channel model, the lightning conductor voltage u is estimated by the following formula:
wherein i is the lightning current and Z is the wave impedance of the lightning channel.
5. The method for simulating the lightning stroke indirect breakdown fault of the power transmission line caused by the bifurcated lightning as claimed in any one of claims 1 to 4, wherein a simulation model is established based on ATP-EMTP.
6. The method for simulating the lightning stroke indirect breakdown fault of the power transmission line caused by the bifurcated lightning as claimed in any one of claims 1 to 4, wherein a J.Marti model is used for establishing the power transmission line model.
7. The method for simulating the lightning strike indirect breakdown fault of the power transmission line caused by the bifurcated lightning as claimed in any one of claims 1 to 4, wherein the simulation model does not relate to a tower.
8. The method for simulating the lightning strike indirect breakdown fault of the power transmission line caused by the bifurcated lightning as claimed in any one of claims 1 to 4, wherein the power transmission line does not consider a transfer substation.
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Cited By (2)
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| CN112052555A (en) * | 2020-07-23 | 2020-12-08 | 南方电网科学研究院有限责任公司 | Simulation method and device for lightning electromagnetic transient model of power transmission line |
| CN115656732A (en) * | 2022-12-12 | 2023-01-31 | 昆明理工大学 | Method and system for identifying lightning stroke fault based on lightning impulse rate |
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| CN102545177A (en) * | 2012-02-21 | 2012-07-04 | 昆明理工大学 | Bergeron-model-based simulation-after-test method for fault phase selection of alternating current transmission line |
| CN108693450A (en) * | 2018-04-09 | 2018-10-23 | 国网电力科学研究院武汉南瑞有限责任公司 | Transmission line of electricity shielding flashover Lightning performance analysis method for the high shaft tower of Great span |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN112052555A (en) * | 2020-07-23 | 2020-12-08 | 南方电网科学研究院有限责任公司 | Simulation method and device for lightning electromagnetic transient model of power transmission line |
| CN112052555B (en) * | 2020-07-23 | 2024-02-23 | 南方电网科学研究院有限责任公司 | Simulation method and device for lightning electromagnetic transient model of power transmission line |
| CN115656732A (en) * | 2022-12-12 | 2023-01-31 | 昆明理工大学 | Method and system for identifying lightning stroke fault based on lightning impulse rate |
| CN115656732B (en) * | 2022-12-12 | 2023-05-23 | 昆明理工大学 | Lightning stroke fault identification method and system based on lightning stroke velocity |
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