CN114091288A - Lightning protection insulator operation life evaluation method for canceling ground wire transmission line - Google Patents
Lightning protection insulator operation life evaluation method for canceling ground wire transmission line Download PDFInfo
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Abstract
The invention provides a method for evaluating the operation life of a lightning protection insulator for canceling a ground wire transmission line, which comprises the following steps: acquiring lightning distribution parameters, tower structures, lead parameters, environmental meteorological parameters and lightning protection insulator technical parameters of a power transmission line with a ground wire to be cancelled; calculating the energy consumed by the lightning protection insulator when the lightning directly strikes the tower every year on the line; calculating the energy consumed by the lightning protection insulator when the lightning directly strikes the lead every year on the line; calculating the lightning energy consumed by the lightning protection insulator when the line is struck by induction lightning every year; calculating the average total lightning impulse discharge energy consumed by the lightning protection insulator every year; carrying out continuous lightning current impact tests on the whole lightning protection insulator to obtain the total lightning impact discharge energy of the lightning protection insulator; and calculating the expected natural operation life N of the lightning protection insulator. The invention can calculate and evaluate the operation life of the lightning protection insulator for canceling the ground wire transmission line, and provides an accurate criterion for replacing the lightning protection insulator.
Description
Technical Field
The invention belongs to the technical field of state evaluation of power transmission line equipment, and particularly relates to a lightning protection insulator operation life evaluation method suitable for a power transmission line without a ground wire.
Background
Compared with a transmission conductor, the ground wire of the overhead line has no current joule heat effect and is positioned above the conductor, the icing is more serious relative to the conductor, and accidents such as ground wire fracture, conductor to ground wire discharge and the like caused by icing are easy to occur, so that power supply interruption is caused. In order to fundamentally eliminate the influence of ground wire icing on the power supply reliability of the power transmission line, an operation mode of canceling the ground wire of the power transmission line in an icing area is often adopted in reality. After the ground wire of the transmission line is removed, the probability and the amplitude of the transmission line subjected to direct attack of lightning current are sharply increased; in order to reduce the risk of flashover tripping when a ground wire power transmission line is subjected to high-amplitude direct lightning, a high-pass current lightning protection insulator capable of resisting high-current direct lightning is often adopted for prevention and treatment.
When a ground wire power transmission line is cancelled to operate, after multiple times of high-amplitude direct lightning current and lightning overvoltage, the internal zinc oxide resistance sheet lightning protection element of the high-through-current lightning protection insulator can generate side flashover, deterioration and thermal breakdown, so that the protection function of the lightning protection insulator is lost, and the lightning trip fault of the power transmission line is caused. Therefore, the operation life of the lightning protection insulator needs to be evaluated according to parameters such as the structure of the power transmission line without the ground wire, lightning waveform, topography and the like, and the lightning protection insulator needs to be replaced before the operation life expires, so that the operation safety and reliability of the power transmission line without the ground wire under the lightning condition are improved. At present, the maximum value of lightning impulse current or charge quantity which can be borne by the lightning arrester is mainly obtained at home and abroad through tests, and is divided by the calculated current or charge quantity of lightning impulse (lightning striking a tower, a wire and the nearby ground) consumed by the lightning arrester in one year, so that the expected service life of the lightning arrester is obtained. Because the lightning current born by the existing lightning arrester when the ground wire transmission line runs is small (mainly around lightning, only 20-40kA), the fault mode of the lightning arrester is mainly represented by the side flashover and the deterioration of an internal resistance sheet caused by the impact current, and the service life of the lightning arrester is effectively calculated by taking the lightning impact current or the electric charge quantity as a criterion. However, after the ground wire of the power transmission line is removed, the lightning current borne by the lightning protection insulator is mainly direct lightning with a large value (generally equal to or more than 40kA), and the fault type mainly shows thermal breakdown or crushing explosion caused by the comprehensive action of lightning impulse current and residual voltage (lightning energy), and at the moment, if the lightning impulse current or the charge amount is still used as a criterion for calculating the service life of the lightning protection insulator, the fault type is obviously not consistent with the actual situation. Under the condition of canceling the ground wire, the calculation method of the lightning current and the residual voltage born by the high-current lightning protection insulator in the lightning stroke is different from that before canceling the ground wire due to the change of structural parameters of a tower-wire system. In summary, the conventional lightning arrester operation life calculation method is not suitable for the lightning protection equipment life evaluation under the condition of canceling the ground wire.
Therefore, aiming at the problems and limitations of the existing lightning arrester operation life calculation method, a lightning protection insulator operation life evaluation method suitable for canceling the ground wire transmission line and comprehensively considering the influence of lightning impulse current and residual voltage needs to be provided urgently, accurate criteria are provided for replacement of the lightning protection insulator, and therefore operation safety and reliability of the ground wire transmission line when the ground wire transmission line is cancelled in a lightning stroke are improved.
Disclosure of Invention
The invention aims to provide a lightning protection insulator operation life evaluation method suitable for canceling a ground wire transmission line, which can comprehensively consider the influence of lightning impulse current and residual voltage, calculate and evaluate the operation life of the lightning protection insulator for canceling the ground wire transmission line and improve the operation safety and reliability of the ground wire transmission line.
In order to achieve the above object, an embodiment of the present invention provides a method for evaluating an operation life of a lightning protection insulator for canceling a ground line transmission line, including:
acquiring lightning distribution parameters, tower structures, lead parameters, environmental meteorological parameters and lightning protection insulator technical parameters of a power transmission line with a ground wire to be cancelled;
calculating the energy W consumed by the lightning protection insulator when the lightning directly strikes the tower in the unit time of the power transmission line of the ground wire to be cancelled1；
Calculating the energy W consumed by the lightning protection insulator when the lightning directly strikes the wire in the unit time of the power transmission line of the ground wire to be cancelled2；
Calculating the lightning energy W consumed by the lightning protection insulator when the power transmission line of the ground wire to be cancelled suffers induction lightning stroke in unit time3；
According to the formula (1), the total lightning impulse discharge energy consumed by the average unit time of the ground wire lightning protection insulator is calculated
Carrying out continuous lightning current impact test on the whole lightning protection insulator to obtain the total lightning impact discharge energy W possessed by the lightning protection insulatorGeneral assembly；
Calculating the expected natural operation life N of the lightning protection insulator according to the formula (2):
in the embodiment of the present invention, it is,
the lightning distribution parameters include: lightning current amplitude probability distribution, ground lightning density and annual average thunderstorm day of the location of the power transmission line;
the pole tower structure comprises: a structural dimension diagram of the transmission line tower;
the wire parameters include: rated voltage of the line, line span and wire spacing, wire type and wave impedance;
the environmental meteorological parameters include: ambient temperature, ambient wind speed; and
the technical parameters of the lightning protection insulator comprise: U-I curve of lightning protection insulator, nominal discharge current INominal scaleDirect current 1mA reference voltage U0And leakage current I0。
In the embodiment of the invention, the energy W consumed by the lightning protection insulator when the lightning directly strikes the tower in the unit time of the transmission line of the ground wire to be cancelled is calculated1The method comprises the following steps:
calculating lightning resistance level I of the power transmission line without the ground wire when the tower is struck by lightning according to a formula (3)m：
Wherein, U50％Is 50% of lightning impulse discharge voltage h of lightning protection insulatordSuspending the wire by an average height, LgtIs tower inductance, RchThe pole tower is an impulse grounding resistor;
calculating the lightning current exceeding the lightning withstand level I based on the probability distribution curve of the lightning current amplitude of the power transmission line without the ground wire according to the formula (4)mProbability of time P:
wherein i is lightning current, δ is a constant related to lightning current density, and γ is a lightning current distribution coefficient;
calculating the number N of times of canceling lightning striking on the tower within 2km of the ground wire transmission line within unit time according to a formula (5)1：
Wherein N isgIs the ground flash density, htB is the height of the tower and the width of the tower structure;
calculating the energy W consumed by directly striking the tower lightning protection insulator by the lightning in unit time according to the formula (6)1：
Wherein T is the lightning current duration of the direct-striking tower, i (T) is the direct-striking lightning current waveform, a 2.6/50 mus double-exponential function is adopted, and u (T) is obtained according to the volt-ampere characteristic curve of the lightning-proof insulator zinc oxide resistor disc:
i(t)＝k(e-αt-e-βt) (7)
u(t)＝ciλ(t) (8)
in the formulas (7) and (8), k is a waveform correction coefficient, alpha and beta are a wavefront attenuation coefficient and a wave tail attenuation coefficient respectively, c is a constant, and lambda is a nonlinear coefficient of the zinc oxide resistor disc.
In the embodiment of the invention, the energy W consumed by the lightning protection insulator when the lightning directly strikes the wire in the unit time of the power transmission line of the ground wire to be cancelled is calculated2The method comprises the following steps:
calculating lightning resistance level I when the ground wire transmission line is not struck by lightning conductor according to formula (9)n：
Wherein, U50％The voltage is 50% of lightning impulse discharge voltage of the lightning protection insulator, and Z is wire wave impedance;
calculating the lightning current exceeding the lightning withstand level I based on the lightning current amplitude probability distribution curve according to the formula (4)nProbability of time P (I)>In)：
Wherein, I is lightning current, delta is a constant related to the lightning current and the lightning density, and gamma is the distribution coefficient of the lightning current;
calculating the times N of canceling the lightning strike of the wire in the 2km range of the ground wire transmission line in unit time according to a formula (10)2：
Wherein N isgIs the ground flash density, htB is the height of the tower and the width of the tower structure;
calculating the energy W consumed by directly striking the wire lightning protection insulator by the lightning in unit time according to the formula (11)2：
Wherein, T is the lightning current duration of the direct attack wire, i (T) adopts the 2.6/50 mus double-exponential lightning current waveform which is the same as that when the lightning directly attacks the tower, u (T) is obtained according to the volt-ampere characteristic curve of the formula (8):
i(t)＝k(e-αt-e-βt) (7)
u(t)＝ciλ(t) (8)
in the formulas (7) and (8), k is a waveform correction coefficient, alpha and beta are a wavefront attenuation coefficient and a wave tail attenuation coefficient respectively, c is a constant, and lambda is a nonlinear coefficient of the zinc oxide resistor disc.
In the embodiment of the invention, the lightning energy W consumed by the lightning protection insulator when the power transmission line of the ground wire to be cancelled suffers induction lightning stroke in unit time is calculated3The method comprises the following steps:
calculating the induced lightning withstand level I of the insulation flashover when the lightning stroke cancels the ground near the ground wire transmission line according to the formula (12)g：
Wherein, U50％50% of lightning impulse discharge voltage of the lightning protection insulator, S is the closest distance between a lightning stroke point and a power transmission line, and k1To sense the overvoltage coefficient, hcAverage height to ground for the wire;
calculating the lightning current exceeding the inductive lightning withstand level I based on the lightning current amplitude probability distribution curve according to the formula (4)gProbability of time P (I)>Ig)：
Wherein, I is lightning current, delta is a constant related to the lightning current and the lightning density, and gamma is the distribution coefficient of the lightning current;
calculating the effective action times N of the induced overvoltage by adopting an integral method according to a formula (13)3：
Wherein N isgIs the ground flash density, l is the line length, s is the distance between the lightning strike point and the transmission line, s1For the lightning-drawing width, s, of one side of the line2The critical width of the induced overvoltage is considered for the line side.
Calculating the energy W consumed by the lightning protection insulator when the power transmission line suffers from the induced lightning in unit time according to the formula (14)3：
Wherein, T is the duration of induced lightning current, i (T) adopts 8.0/20 mus double-exponential lightning current waveform, u (T) is obtained according to the volt-ampere characteristic curve of the formula (8):
i(t)＝k(e-αt-e-βt) (7)
u(t)＝ciλ(t) (8)
in the formulas (7) and (8), k is a waveform correction coefficient, alpha and beta are a wavefront attenuation coefficient and a wave tail attenuation coefficient respectively, c is a constant, and lambda is a nonlinear coefficient of the zinc oxide resistor disc.
In the embodiment of the invention, the whole lightning protection insulator is subjected to continuous lightning current surge test to obtain the total lightning surge discharge energy W owned by the lightning protection insulatorGeneral assemblyThe method comprises the following steps:
step S61: the method comprises the steps that an entire lightning protection insulator impulse current test platform is set up, the entire lightning protection insulator impulse current test platform comprises an impulse current generator and a wave regulating inductor, the impulse current generator is used for generating 8/20 mu s or 2.6/50 mu s lightning current waveforms, the output side of the impulse current generator is connected with a lightning protection section of the lightning protection insulator through the wave regulating inductor, and the entire lightning protection insulator impulse current test platform further comprises a residual voltage measuring voltage divider used for measuring the residual voltage of the lightning current after passing through the lightning protection insulator;
step S62: connecting the working power supply of the impulse current generator, and applying the nominal discharge current amplitude I to the whole lightning protection insulator test sampleNominal scaleEqual 8/20 mus or 2.6/50 mus lightning current, while recording the residual voltage U at 8/20 mus or 2.6/50 mus lightning currentResidual pressure；
Step S63: after the temperature of the lightning protection insulator sample is restored to normal temperature, measuring the direct current 1mA reference voltage U of the lightning protection insulator by using a direct current high voltage generator1mAAnd leakage current ILeakage of；
Step S64: repeating the steps S62 and S63 until the lightning protection insulatorDC 1mA reference voltage U1mA≤0.9U0Or leakage current ILeakage of≥50μA；
Step S65: according to the formula (15), the sum of the lightning energy absorbed by the lightning protection insulator under the action of all 8/20 mu s or 2.6/50 mu s lightning current is taken as the total possessed lightning impulse discharge energy WGeneral assembly：
Wherein, i (T), u (T) are numerical expressions of lightning current and residual voltage waveform respectively, and T is duration of lightning current; i (t) is a 2.6/50 mus or 8.0/20 mus double-exponential function, and u (t) is obtained according to a voltage-current characteristic curve of the lightning protection insulator zinc oxide resistance card:
i(t)＝k(e-αt-e-βt) (7)
u(t)＝ciλ(t) (8)
in the formulas (7) and (8), k is a waveform correction coefficient, alpha and beta are a wavefront attenuation coefficient and a wave tail attenuation coefficient respectively, c is a constant, and lambda is a nonlinear coefficient of the zinc oxide resistor disc.
In the embodiment of the present invention, the unit time is one year.
The method provided by the embodiment of the invention has the following beneficial effects:
(1) the operation life of the lightning protection insulator for canceling the ground wire transmission line can be calculated and evaluated, and accurate criteria are provided for replacing the lightning protection insulator;
(2) the running life of the lightning protection insulator comprehensively considering the influence of lightning impulse current and residual voltage (lightning energy) can be obtained, and the running safety and reliability of the power transmission line without the ground wire when being struck by lightning are improved;
(3) the evaluation method is easy to realize and strong in operability, and provides a complete and reliable design scheme for predicting the service life of the lightning protection insulator applied to the power transmission line without the ground wire in the repeated icing area;
(4) the method is suitable for calculating and evaluating the service life of the power transmission line lightning protection insulator with the voltage class of 10-500 kV in the repeated icing area.
Additional features and advantages of embodiments of the invention will be set forth in the detailed description which follows.
Drawings
The accompanying drawings, which are included to provide a further understanding of the embodiments of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the embodiments of the invention without limiting the embodiments of the invention. In the drawings:
fig. 1 schematically shows a flow chart of a method for operational lifetime assessment of a lightning protection insulator for cancelling a ground transmission line according to an embodiment of the invention;
FIG. 2 schematically illustrates a principle diagram of a lightning current surge test of a complete product of a lightning protection insulator according to an embodiment of the invention;
fig. 3 schematically shows a schematic structural diagram of eliminating a ground transmission line tower according to an embodiment of the invention.
Detailed Description
The following detailed description of embodiments of the invention refers to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating embodiments of the invention, are given by way of illustration and explanation only, not limitation.
Fig. 1 schematically shows a flow chart of a method for operational lifetime assessment of a lightning protection insulator for cancelling a ground transmission line according to an embodiment of the invention. As shown in fig. 1, in an embodiment of the present invention, a method for evaluating an operation life of a lightning protection insulator for canceling a ground transmission line is provided, and the method may include the following steps.
In step S11, acquiring lightning distribution parameters, tower structure, conductor parameters, environmental weather parameters, and lightning protection insulator technical parameters of the transmission line of the ground wire to be cancelled;
in step S12, calculating the energy W consumed by the lightning protection insulator when the lightning directly strikes the tower in the unit time of the transmission line of the ground wire to be cancelled1；
In step S13, the destination to be cancelled is calculatedEnergy W consumed by lightning protection insulator when lightning directly strikes lead in unit time of line transmission line2；
In step S14, calculating the lightning energy W consumed by the lightning protection insulator when the power transmission line of the ground wire to be cancelled suffers an induced lightning stroke in unit time3；
In step S15, the total lightning impulse discharge energy consumed by the average unit time of the ground wire lightning protection insulator is cancelled is calculated according to the formula (1)
In step S16, a continuous lightning current surge test is performed on the entire lightning protection insulator to obtain the total lightning surge discharge energy W of the lightning protection insulatorGeneral assembly；
In step S17, the expected natural operation life N of the lightning protection insulator is calculated according to the formula (2):
specifically, the lightning distribution parameters may include: lightning current amplitude probability distribution, ground lightning density and annual average thunderstorm day of the location of the power transmission line;
the pole tower structure comprises: a structural dimension diagram of the transmission line tower;
the wire parameters include: rated voltage of the line, line span and wire spacing, wire type and wave impedance;
the environmental meteorological parameters include: ambient temperature, ambient wind speed; and
the technical parameters of the lightning protection insulator comprise: U-I curve of lightning protection insulator, nominal discharge current INominal scaleDirect current 1mA reference voltage U0And leakage current I0。
In the practice of the inventionIn an example, the energy W consumed by the lightning protection insulator when the lightning directly strikes the tower in the unit time of the transmission line of the ground wire to be cancelled is calculated1The method comprises the following steps:
calculating lightning resistance level I of the power transmission line without the ground wire when the tower is struck by lightning according to a formula (3)m：
Wherein, U50％Is 50% of lightning impulse discharge voltage h of lightning protection insulatordSuspending the wire by an average height, LgtIs tower inductance, RchThe pole tower is an impulse grounding resistor;
calculating the lightning current exceeding the lightning withstand level I based on the probability distribution curve of the lightning current amplitude of the power transmission line without the ground wire according to the formula (4)mProbability of time P:
wherein i is lightning current, δ is a constant related to lightning current density, and γ is a lightning current distribution coefficient;
calculating the number N of times of canceling lightning striking on the tower within 2km of the ground wire transmission line within unit time according to a formula (5)1：
Wherein N isgIs the ground flash density, htB is the height of the tower and the width of the tower structure;
calculating the energy W consumed by directly striking the tower lightning protection insulator by the lightning in unit time according to the formula (6)1：
Wherein T is the lightning current duration of the direct-striking tower, i (T) is the direct-striking lightning current waveform, a 2.6/50 mus double-exponential function is adopted, and u (T) is obtained according to the volt-ampere characteristic curve of the lightning-proof insulator zinc oxide resistor disc:
i(t)＝k(e-αt-e-βt) (7)
u(t)＝ciλ(t) (8)
in the formulas (7) and (8), k is a waveform correction coefficient, alpha and beta are a wavefront attenuation coefficient and a wave tail attenuation coefficient respectively, c is a constant, and lambda is a nonlinear coefficient of the zinc oxide resistor disc.
In the embodiment of the invention, the energy W consumed by the lightning protection insulator when the lightning directly strikes the wire in the unit time of the power transmission line of the ground wire to be cancelled is calculated2The method comprises the following steps:
calculating lightning resistance level I when the ground wire transmission line is not struck by lightning conductor according to formula (9)n：
Wherein, U50％The voltage is 50% of lightning impulse discharge voltage of the lightning protection insulator, and Z is wire wave impedance;
calculating the lightning current exceeding the lightning withstand level I based on the lightning current amplitude probability distribution curve according to the formula (4)nProbability of time P (I)>In)：
Wherein, I is lightning current, delta is a constant related to the lightning current and the lightning density, and gamma is the distribution coefficient of the lightning current;
calculating the times N of canceling the lightning strike of the wire in the 2km range of the ground wire transmission line in unit time according to a formula (10)2：
Wherein N isgIs the ground flash density, htB is the height of the tower and the width of the tower structure;
calculating the energy W consumed by directly striking the wire lightning protection insulator by the lightning in unit time according to the formula (11)2：
Wherein, T is the lightning current duration of the direct attack wire, i (T) adopts the 2.6/50 mus double-exponential lightning current waveform which is the same as that when the lightning directly attacks the tower, u (T) is obtained according to the volt-ampere characteristic curve of the formula (8):
i(t)＝k(e-αt-e-βt) (7)
u(t)＝ciλ(t) (8)
in the formulas (7) and (8), k is a waveform correction coefficient, alpha and beta are a wavefront attenuation coefficient and a wave tail attenuation coefficient respectively, c is a constant, and lambda is a nonlinear coefficient of the zinc oxide resistor disc.
In the embodiment of the invention, the lightning energy W consumed by the lightning protection insulator when the power transmission line of the ground wire to be cancelled suffers induction lightning stroke in unit time is calculated3The method comprises the following steps:
calculating the induced lightning withstand level I of the insulation flashover when the lightning stroke cancels the ground near the ground wire transmission line according to the formula (12)g：
Wherein, U50％50% of lightning impulse discharge voltage of the lightning protection insulator, S is the closest distance between a lightning stroke point and a power transmission line, and k1To sense the overvoltage coefficient, hcAverage height to ground for the wire;
calculating the lightning current exceeding the inductive lightning withstand level I based on the lightning current amplitude probability distribution curve according to the formula (4)gProbability of time P (I)>Ig)：
Wherein, I is lightning current, delta is a constant related to the lightning current and the lightning density, and gamma is the distribution coefficient of the lightning current;
calculating the effective action times N of the induced overvoltage by adopting an integral method according to a formula (13)3：
Wherein Ng is the ground lightning density, l is the line length, s is the distance between the lightning stroke point and the power transmission line, and s1For lightning strike width on one side of the line (generally considered to be less than this width, lightning strikes the line directly), s2The critical width of the induced overvoltage is considered for the line side.
Calculating the energy W consumed by the lightning protection insulator when the power transmission line suffers from the induced lightning in unit time according to the formula (14)3：
Wherein, T is the duration of induced lightning current, i (T) adopts 8.0/20 mus double-exponential lightning current waveform, u (T) is obtained according to the volt-ampere characteristic curve of the formula (8):
i(t)＝k(e-αt-e-βt) (7)
u(t)＝ciλ(t) (8)
in the formulas (7) and (8), k is a waveform correction coefficient, alpha and beta are a wavefront attenuation coefficient and a wave tail attenuation coefficient respectively, c is a constant, and lambda is a nonlinear coefficient of the zinc oxide resistor disc.
In the embodiment of the invention, the whole lightning protection insulator is subjected to continuous lightning current surge test to obtain the total lightning surge discharge energy W owned by the lightning protection insulatorGeneral assemblyThe method comprises the following steps:
step S61: a whole lightning protection insulator impulse current test platform is set up (as shown in fig. 2), and the whole lightning protection insulator impulse current test platform comprises an impulse current generator 21 and a wave modulation inductor R0The surge current generator 21 is used for generating 8/20 mu s or 2.6/50 mu s lightning current waveform, and the output side of the surge current generator 21 is provided with a wave-regulating inductor R0The whole lightning protection insulator impulse current test platform further comprises a residual voltage measurement voltage divider 22, which is used for measuring the residual voltage of the lightning current after passing through the lightning protection insulator 23;
step S62: connecting the working power supply of the impulse current generator, and applying the nominal discharge current amplitude I to the whole lightning protection insulator test sampleNominal scaleEqual 8/20 mus or 2.6/50 mus lightning current, while recording the residual voltage U at 8/20 mus or 2.6/50 mus lightning currentResidual pressure；
Step S63: after the temperature of the lightning protection insulator sample is restored to normal temperature, measuring the direct current 1mA reference voltage U of the lightning protection insulator by using a direct current high voltage generator1mAAnd leakage current ILeakage of；
Step S64: repeating the steps S62 and S63 until the lightning protection insulator DC 1mA reference voltage U1mA≤0.9U0Or leakage current ILeakage of≥50μA；
Step S65: according to the formula (15), the sum of the lightning energy absorbed by the lightning protection insulator under the action of all 8/20 mu s or 2.6/50 mu s lightning current is taken as the total possessed lightning impulse discharge energy WGeneral assembly：
Wherein, i (T), u (T) are numerical expressions of lightning current and residual voltage waveform respectively, and T is duration of lightning current; i (t) is a 2.6/50 mus or 8.0/20 mus double-exponential function, and u (t) is obtained according to a voltage-current characteristic curve of the lightning protection insulator zinc oxide resistance card:
i(t)＝k(e-αt-e-βt) (7)
u(t)＝ciλ(t) (8)
in the formulas (7) and (8), k is a waveform correction coefficient, alpha and beta are a wavefront attenuation coefficient and a wave tail attenuation coefficient respectively, c is a constant, and lambda is a nonlinear coefficient of the zinc oxide resistor disc.
In the embodiment of the present invention, the unit time may be one month, one quarter, one year, and preferably, the unit time may be one year.
And (4) carrying out operation life evaluation on the lightning protection insulator of the 110kV power transmission line without the ground wire in the repeated ice area by combining the attached drawings. The example method may include the following steps.
(1) Acquiring lightning distribution parameters, tower structure and wire parameters, environmental meteorological parameters and lightning protection insulator technical parameters of a 110kV power transmission line with a ground wire to be cancelled, wherein the lightning distribution parameters comprise lightning current amplitude probability distribution, ground lightning density and annual average thunderstorm day of the power transmission line, and are shown in table 1; the parameters of the transmission line tower and the conducting wires comprise a tower structure size diagram, line rated voltage, line span and conducting wire spacing, conducting wire model and wave impedance, and are shown in a table 2; the environmental meteorological parameters comprise environmental temperature, environmental wind speed and the like; as shown in Table 3; the technical parameters of the lightning protection insulator comprise a U-I curve and a nominal discharge current INominal scaleDirect current 1mA reference voltage U0And leakage current I0As shown in table 4.
TABLE 1 cancellation of lightning distribution parameters of 110kV power transmission line with ground wire
TABLE 2 cancellation of ground wire 110kV transmission line tower and wire parameters
| Rated voltage | Tower structure dimension diagram | Line pitch/wire pitch | Type of wire | Line wave impedance |
| 110kV | FIG. 3 | 200m/6m | LGJ-240/40 | 400 ohm |
TABLE 3 cancellation of ground wire 110kV transmission line environmental meteorological parameters
| Minimum temperature | Mean wind speed | Altitude (H) level | Maximum ice coating thickness | Relative humidity | Air pressure | Amount of rainfall in the day |
| -12℃ | 5m/s | 1385m | 30mm | 86.8％ | 861hPa | 144.6mm |
TABLE 4 parameters for eliminating 110kV transmission line lightning protection insulator of ground wire
(2) Calculating the energy W consumed by the 110kV lightning protection insulator when the 110kV power transmission line with the ground wire to be cancelled directly strikes the tower every year by lightning1。
(2.1) calculating lightning resistance level I when the 110kV power transmission line of the ground wire is not struck by the lightning towerm。
In the above formula, U50％Is 50% of lightning impulse discharge voltage h of lightning protection insulatordSuspending the wire by an average height, LgtThe pole tower inductance is obtained; rchThe pole tower impulse grounding resistor. For 110kV power transmission line without ground wire, U50％Is 425kV, hdThe inductance per unit length of the tower is 27.8m, Lgt is the product of the inductance per unit length of the tower and the height of the tower, and 0.5 x 29.1 is 14.55 mu H; rchTaking 12 omega, calculating to obtain Im＝15kA。
(2.2) calculating lightning current exceeding lightning resistance level I according to the probability distribution curve of the lightning current amplitude of the 110kV power transmission line without the ground wiremThe probability P of time.
Will ImEquation (17) is substituted for 15kA, and the calculation is performedTo P (i)>15kA)＝88.44％。
(2.3) calculating the number N of times of lightning striking towers within 2km of each year of the ground wire transmission line1。
From the data in Table 1, Table 2 and FIG. 3, the lightning density NgIs 3.12 times/(km)2A), tower height htThe width b of the tower structure is 12m, and N is obtained by calculation134.88 times/(100 km.a).
2.4) calculating the energy W consumed by lightning direct-striking the tower lightning protection insulator every year1。
In the formula (19), i (t) is a 2.6/50 μ s direct lightning current waveform, and the direct lightning current waveform is fitted by using a double-exponential function to obtain a numerical expression of i (t):
the residual voltage of the 110kV lightning protection insulator under the action of 2.6/50 mu s lightning current can be obtained according to a numerical expression of a Voltan characteristic curve in a table 4, namely:
writing a program in MATLAB software, and calculating to obtain ImEnergy W consumed by 110kV lightning protection insulator when 34kA lightning current directly strikes tower1Comprises the following steps:
(3) calculating 110kV transmission of ground wire to be cancelledEnergy W consumed by 110kV lightning protection insulator when lightning directly strikes lead in each year on electric line2。
(3.1) calculating lightning resistance level I when the 110kV power transmission line of the ground wire is not struck by lightningn(Z is the wire wave impedance).
In the above formula, U50％The wave impedance of the 110kV line is 300 omega when 425kV is obtained, and I is obtained by calculationn＝5.67kA。
(3.2) calculating the lightning current exceeding the lightning endurance level I according to the lightning current amplitude probability distribution curve in the formula (4)nProbability P (I) at 5.67kA>5.67kA)＝0.9937。
(3.3) calculating the number N of times of canceling lightning strike on the wire in the 2km range of the ground wire transmission line per year2＝N134.88 times/(100 km.a).
(3.4) calculating the energy W consumed by lightning direct-striking the wire lightning protection insulator every year2。
Similar to step (2), I is calculatednEnergy W consumed by 110kV lightning protection insulator when 5.67kA lightning current directly strikes lead1Comprises the following steps:
(4) calculating the lightning energy W consumed by the 110kV lightning protection insulator when the 110kV power transmission line of the ground wire to be cancelled suffers induction lightning stroke every year3。
(4.1) calculating the induced lightning withstand level I of the insulation flashover caused by canceling the ground near the ground wire transmission line by lightning strikeg。
In the above formula, U50％425kV, 134m of lightning strike width w, 67m of closest distance S between a lightning strike point and a power transmission line w/2, and induced overvoltage coefficient k125, average wire height h to groundcAt 25.5m, I is calculatedg＝44.67kA。
(4.2) calculating the lightning current exceeding the induction lightning withstand level I according to the lightning current amplitude probability distribution curve in the formula (4)gProbability P (I) at 44.67kA>44.67kA)＝0.207。
(4.3) calculating the effective action times N of the induced overvoltage by adopting an integral method3。
In the formula (27), the ground flash density NgIs 3.12 times/(km)2A), the line length l is taken as 2km, P is calculated by formula (4), s1For the lightning strike width of one side of the line, take s1＝w/2＝67m，s2Taking s as the critical width of the line side considering the action of the induced overvoltage1Writing program in MATLAB software, and calculating to obtain N30.22 times/(100 km.a)
(4.4) calculating the energy W consumed by the lightning protection insulator when the power transmission line is subjected to the inductive lightning every year3。
In the formula (28), T is duration of induced lightning current, 1000 μ S is taken, S is critical width of induced overvoltage 670m, Ig(s) using formula (26), i (t) using 8.0/20 μ s double-exponential lightning current waveform, fitting it with double-exponential function to obtain the numerical expression of i (t):
u (t) is obtained according to a formula (21) volt-ampere characteristic curve, a program is written in MATLAB software, and the energy W consumed by the 110kV lightning protection insulator under the action of induced lightning current is calculated3Comprises the following steps:
(5) the total lightning impulse discharge energy consumed by the lightning protection insulator of the 110kV line without the ground wire in average each year is calculated according to the formula (31)
(6) Carrying out continuous lightning current (8/20 mus or 2.6/50) impact test on the whole 110kV lightning protection insulator to obtain the total lightning impact discharge energy W owned by the lightning protection insulatorGeneral assembly。
(6.1) building a whole 110kV lightning protection insulator impact current test platform in a high-voltage test hall according to the figure 2. Wherein the surge current generator 21 is used for generating 8/20 mus or 2.6/50 mus lightning current waveform, and the output side of the surge current generator is provided with a wave-regulating inductor R0And the residual voltage measuring voltage divider 22 is connected with the lightning protection section of the 110kV lightning protection insulator 23 and is used for measuring the residual voltage of lightning current passing through the lightning protection insulator 23.
(6.2) switching on the working power supply of the impulse current generator to apply I to the 110kV lightning protection insulatorNominal scale8/20 mus lightning current at 10kA while recording the residual voltage U at 8/20 mus lightning currentResidual pressureAs shown in table 5.
TABLE 5 Whole 110kV lightning protection insulator 8/20 mus impulse current test results
(6.3) after each 8/20 μ s rush current testAfter the temperature of the 110kV lightning protection insulator sample is restored to normal temperature, measuring the direct current 1mA reference voltage U of the lightning protection insulator by using a direct current high voltage generator1mAAnd leakage current ILeakage ofAs shown in table 5.
(6.4) repeating the steps 6.2) and 6.3) until the direct current of the lightning protection insulator is 1mA reference voltage U1mA≤0.9U0Or leakage current ILeakage ofNot less than 50 muA, as can be seen from Table 5, when the test times are repeated to 696 th time, the direct current of the 110kV lightning protection insulator is 1mA voltage U1mA＝116.50<134×0.9＝120.6。
(6.5) the sum of the lightning energy absorbed by the 110kV lightning protection insulator from the 1 st to the 695 th times of 8/20 mu s of impact current is taken as the owned lightning impact discharge total energy to obtain WGeneral assembly＝164.159MJ。
(7) And (3) calculating the expected natural operation life N of the 110kV lightning protection insulator for canceling the ground wire in the repeated ice-covered area according to the formula (9) to be 16.52 years.
The method for evaluating the operation life of the lightning protection insulator for canceling the ground wire transmission line provided by the embodiment of the invention has the beneficial effects that:
(1) the method can be used for calculating and evaluating the operation life of the lightning protection insulator for canceling the ground wire transmission line, and provides an accurate criterion for replacing the lightning protection insulator.
(2) The lightning protection insulator operation life comprehensively considering the influence of lightning impulse current and residual voltage (lightning energy) can be obtained, and the operation safety and reliability of the power transmission line without the ground wire when being struck by lightning are improved.
(3) The evaluation method is easy to implement and strong in operability, and provides a complete and reliable design scheme for predicting the service life of the lightning protection insulator applied to the power transmission line without the ground wire in the repeated icing area.
(4) The method is suitable for calculating and evaluating the service life of the power transmission line lightning protection insulator with the voltage class of 10-500 kV in the repeated icing area.
As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
In a typical configuration, a computing device includes one or more processors (CPUs), input/output interfaces, network interfaces, and memory.
The memory may include forms of volatile memory in a computer readable medium, Random Access Memory (RAM) and/or non-volatile memory, such as Read Only Memory (ROM) or flash memory (flash RAM). The memory is an example of a computer-readable medium.
Computer-readable media, including both non-transitory and non-transitory, removable and non-removable media, may implement information storage by any method or technology. The information may be computer readable instructions, data structures, modules of a program, or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), Static Random Access Memory (SRAM), Dynamic Random Access Memory (DRAM), other types of Random Access Memory (RAM), Read Only Memory (ROM), Electrically Erasable Programmable Read Only Memory (EEPROM), flash memory or other memory technology, compact disc read only memory (CD-ROM), Digital Versatile Discs (DVD) or other optical storage, magnetic cassettes, magnetic tape magnetic disk storage or other magnetic storage devices, or any other non-transmission medium that can be used to store information that can be accessed by a computing device. As defined herein, a computer readable medium does not include a transitory computer readable medium such as a modulated data signal and a carrier wave.
It should also be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in the process, method, article, or apparatus that comprises the element.
The above are merely examples of the present application and are not intended to limit the present application. Various modifications and changes may occur to those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.
Claims (7)
1. A lightning protection insulator operation life assessment method for canceling a ground wire transmission line is characterized by comprising the following steps:
acquiring lightning distribution parameters, tower structures, lead parameters, environmental meteorological parameters and lightning protection insulator technical parameters of a power transmission line with a ground wire to be cancelled;
calculating the energy W consumed by the lightning protection insulator when the lightning directly strikes the tower in the unit time of the power transmission line of the ground wire to be cancelled1；
Calculating the energy W consumed by the lightning protection insulator when the lightning directly strikes the wire in the unit time of the power transmission line of the ground wire to be cancelled2；
Calculating the lightning energy W consumed by the lightning protection insulator when the power transmission line of the ground wire to be cancelled suffers induction lightning stroke in unit time3；
According to the formula (1), the total lightning impulse discharge energy consumed by the average unit time of the ground wire lightning protection insulator is calculated
Carrying out continuous lightning current impact test on the whole lightning protection insulator to obtain the total lightning impact discharge energy W possessed by the lightning protection insulatorGeneral assembly；
Calculating the expected natural operation life N of the lightning protection insulator according to the formula (2):
2. the evaluation method according to claim 1,
the lightning distribution parameters include: lightning current amplitude probability distribution, ground lightning density and annual average thunderstorm day of the location of the power transmission line;
the pole tower structure comprises: a structural dimension diagram of the transmission line tower;
the wire parameters include: rated voltage of the line, line span and wire spacing, wire type and wave impedance;
the environmental meteorological parameters include: ambient temperature, ambient wind speed; and
the technical parameters of the lightning protection insulator comprise: U-I curve of lightning protection insulator, nominal discharge current INominal scaleDirect current 1mA reference voltage U0And leakage current I0。
3. The evaluation method according to claim 1, wherein the energy W consumed by the lightning protection insulator when the lightning directly strikes the tower in the unit time of the ground wire transmission line to be cancelled is calculated1The method comprises the following steps:
calculating lightning resistance level I of the power transmission line without the ground wire when the tower is struck by lightning according to a formula (3)m：
Wherein, U50％Is 50% of lightning impulse discharge voltage h of lightning protection insulatordSuspending the wire by an average height, LgtIs tower inductance, RchThe pole tower is an impulse grounding resistor;
calculating the lightning current exceeding the lightning withstand level I based on the probability distribution curve of the lightning current amplitude of the power transmission line without the ground wire according to the formula (4)mProbability of time P:
wherein i is lightning current, δ is a constant related to lightning current density, and γ is a lightning current distribution coefficient;
calculating the number N of times of canceling lightning striking on the tower within 2km of the ground wire transmission line within unit time according to a formula (5)1：
Wherein N isgIs the ground flash density, htB is the height of the tower and the width of the tower structure;
calculating the energy W consumed by directly striking the tower lightning protection insulator by the lightning in unit time according to the formula (6)1：
Wherein T is the lightning current duration of the direct-striking tower, i (T) is the direct-striking lightning current waveform, a 2.6/50 mus double-exponential function is adopted, and u (T) is obtained according to the volt-ampere characteristic curve of the lightning-proof insulator zinc oxide resistor disc:
i(t)＝k(e-αt-e-βt) (7)
u(t)＝ciλ(t) (8)
in the formulas (7) and (8), k is a waveform correction coefficient, alpha and beta are a wavefront attenuation coefficient and a wave tail attenuation coefficient respectively, c is a constant, and lambda is a nonlinear coefficient of the zinc oxide resistor disc.
4. The evaluation method according to claim 1, wherein the energy W consumed by the lightning protection insulator when the lightning strikes the wire directly in the unit time of the ground transmission line to be cancelled is calculated2The method comprises the following steps:
calculating lightning resistance level I when the ground wire transmission line is not struck by lightning conductor according to formula (9)n：
Wherein, U50％The voltage is 50% of lightning impulse discharge voltage of the lightning protection insulator, and Z is wire wave impedance;
calculating the lightning current exceeding the lightning withstand level I based on the lightning current amplitude probability distribution curve according to the formula (4)nProbability of time P (I)>In)：
Wherein, I is lightning current, delta is a constant related to the lightning current and the lightning density, and gamma is the distribution coefficient of the lightning current;
calculating the times N of canceling the lightning strike of the wire in the 2km range of the ground wire transmission line in unit time according to a formula (10)2：
Wherein N isgIs the ground flash density, htB is the height of the tower and the width of the tower structure;
calculating the energy W consumed by directly striking the wire lightning protection insulator by the lightning in unit time according to the formula (11)2：
Wherein, T is the lightning current duration of the direct attack wire, i (T) adopts the 2.6/50 mus double-exponential lightning current waveform which is the same as that when the lightning directly attacks the tower, u (T) is obtained according to the volt-ampere characteristic curve of the formula (8):
i(t)＝k(e-αt-e-βt) (7)
u(t)＝ciλ(t) (8)
in the formulas (7) and (8), k is a waveform correction coefficient, alpha and beta are a wavefront attenuation coefficient and a wave tail attenuation coefficient respectively, c is a constant, and lambda is a nonlinear coefficient of the zinc oxide resistor disc.
5. The evaluation method according to claim 1, wherein the amount of lightning energy consumed by the lightning protection insulator when the to-be-cancelled ground wire transmission line is struck by inductive lightning in unit time is calculated as W3The method comprises the following steps:
calculating the induced lightning withstand level I of the insulation flashover when the lightning stroke cancels the ground near the ground wire transmission line according to the formula (12)g：
Wherein, U50％50% of lightning impulse discharge voltage of the lightning protection insulator, S is the closest distance between a lightning stroke point and a power transmission line, and k1To sense the overvoltage coefficient, hcAverage height to ground for the wire;
calculating the lightning current exceeding the inductive lightning withstand level I based on the lightning current amplitude probability distribution curve according to the formula (4)gProbability of time P (I)>Ig)：
Wherein, I is lightning current, delta is a constant related to the lightning current and the lightning density, and gamma is the distribution coefficient of the lightning current;
calculating the effective action times N of the induced overvoltage by adopting an integral method according to a formula (13)3：
Wherein N isgIs the ground flash density, l is the line length, s is the distance between the lightning strike point and the transmission line, s1For the lightning-drawing width, s, of one side of the line2Is one side of the lineConsider the critical width of induced overvoltages.
Calculating the energy W consumed by the lightning protection insulator when the power transmission line suffers from the induced lightning in unit time according to the formula (14)3：
Wherein, T is the duration of induced lightning current, i (T) adopts 8.0/20 mus double-exponential lightning current waveform, u (T) is obtained according to the volt-ampere characteristic curve of the formula (8):
i(t)＝k(e-αt-e-βt) (7)
u(t)＝ciλ(t) (8)
in the formulas (7) and (8), k is a waveform correction coefficient, alpha and beta are a wavefront attenuation coefficient and a wave tail attenuation coefficient respectively, c is a constant, and lambda is a nonlinear coefficient of the zinc oxide resistor disc.
6. The method of claim 1, wherein the entire lightning protection insulator is subjected to successive lightning strike tests to obtain the total lightning strike discharge energy W possessed by the lightning protection insulatorGeneral assemblyThe method comprises the following steps:
step S61: the method comprises the steps that an entire lightning protection insulator impulse current test platform is set up, the entire lightning protection insulator impulse current test platform comprises an impulse current generator and a wave regulating inductor, the impulse current generator is used for generating 8/20 mu s or 2.6/50 mu s lightning current waveforms, the output side of the impulse current generator is connected with a lightning protection section of the lightning protection insulator through the wave regulating inductor, and the entire lightning protection insulator impulse current test platform further comprises a residual voltage measuring voltage divider used for measuring the residual voltage of the lightning current after passing through the lightning protection insulator;
step S62: connecting the working power supply of the impulse current generator, and applying the nominal discharge current amplitude I to the whole lightning protection insulator test sampleNominal scaleEqual 8/20 mus or 2.6/50 mus lightning current, while recording the residual voltage U at 8/20 mus or 2.6/50 mus lightning currentResidual pressure；
Step S63: after the temperature of the lightning protection insulator sample is restored to normal temperature, measuring the direct current 1mA reference voltage U of the lightning protection insulator by using a direct current high voltage generator1mAAnd leakage current ILeakage of；
Step S64: repeating the steps S62 and S63 until the lightning protection insulator DC 1mA reference voltage U1mA≤0.9U0Or leakage current ILeakage of≥50μA；
Step S65: according to the formula (15), the sum of the lightning energy absorbed by the lightning protection insulator under the action of all 8/20 mu s or 2.6/50 mu s lightning current is taken as the total possessed lightning impulse discharge energy WGeneral assembly：
Wherein, i (T), u (T) are numerical expressions of lightning current and residual voltage waveform respectively, and T is duration of lightning current; i (t) is a 2.6/50 mus or 8.0/20 mus double-exponential function, and u (t) is obtained according to a voltage-current characteristic curve of the lightning protection insulator zinc oxide resistance card:
i(t)＝k(e-αt-e-βt) (7)
u(t)＝ciλ(t) (8)
in the formulas (7) and (8), k is a waveform correction coefficient, alpha and beta are a wavefront attenuation coefficient and a wave tail attenuation coefficient respectively, c is a constant, and lambda is a nonlinear coefficient of the zinc oxide resistor disc.
7. The evaluation method according to any one of claims 1 to 6, wherein the unit time is one year.
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