CN105118588A - Method of parallel gap design of composite insulators of 500-kV power transmission line - Google Patents
Method of parallel gap design of composite insulators of 500-kV power transmission line Download PDFInfo
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Abstract
The invention discloses a method of a parallel gap design of composite insulators of a 500-kV power transmission line. The method comprises the following steps: (1), determining a shape of a parallel-gap arcing electrode; (2), determining a material of the parallel-gap arcing electrode; (3), determining an interface of the parallel-gap arcing electrode; (4), determining a geometric dimension of a parallel gap; (5), designing a parallel-gap connection armour clamp; and (6), carrying out parallel-gap electrical performance testing. According to the invention, the method is especially suitable for a parallel gap design of composite insulators of a 500-kV power transmission line, wherein the parallel gap has the advantages of good voltage sharing performance, fast arc-guiding speed, and good protection effect.
Description
Technical field
The present invention relates to the technical field of parallel connection gaps lightning protection, refer in particular to a kind of method for designing of 500kV transmission line composite insulator parallel connection gaps.
Background technology
Along with economic development, Electricity Demand constantly increases.But the distribution of China's electric energy and consumption are unbalanced.Coastal area is populous, and economy is more flourishing, consume the more energy, also just needs more supply of electric power, has therefore also just had " transferring electricity from the west to the east " engineering.Want long distance delivery electric energy, super UHV transmission line will be adopted.Extra high voltage network has the features such as transmission capacity is large, distribution lines is many, have a very wide distribution, its regional landform that will cross over, weather conditions are very complicated, various factors impact can be subject in transmission line running and produce fault, as thunderbolt, filth, icing etc.This wherein ultra-high-tension power transmission line lightning stroke trip fault especially oneself through becoming the difficult problem affecting countries in the world power grid security and power.
The existing lightning protection measures of aerial power transmission line has: set up lightning conducter, reduce earth resistance, improve insulation configuration, install coupled ground-wire additional, install leakage conductor etc.Its core concept improves the lightning withstand level of circuit as much as possible, reduces tripping rate with lightning strike.These lightning protection measuress can be summarized as the mode of " blocking type " lightning protection.
In recent years, along with China's electrical network is fast-developing, grid structure strengthens day by day.And along with technological progress, transformer station adopts SF6 circuit breaker in a large number, and relaying protection realizes Microcomputer, and reclosing device is generally used, if now still continue to use " blocking type " lightning protection mode, inadequate.Eye is invested the Lightning Protection of parallel connection gaps lightning protection this " diverting type " by power department.Parallel connection gaps lightning protection, utilizes exactly and in parallel asks the lightning impulse flashover voltage of gap this feature of lightning impulse flashover voltage lower than insulator string, allows lightning protection inter space discharging in advance, thus plays the effect of protection insulator.
Parallel connection gaps lightning protection is the lightning protection mode of the one " diverting type " different with traditional lightning protection mode.Due to advantages such as the know-why of parallel connection gaps lightning protection mode are unique, apparatus structure is simple, easy for installation, economic performance is excellent, it is subject to acceptance and the favor of power department just gradually.China's parallel connection gaps Research foundation is weak, particularly few to the research of the parallel clearance for 500kV power transmission line, and around shocking overvoltage is the main cause of 500kV transmission line malfunction.Therefore, based on Ansys simulation software, build 500kV electric transmission line isolator model, and a kind of 500kV of design invention all presses parallel connection gaps of good performance, for exploitation function admirable, the parallel connection clearance device that can drop into Practical Project, be necessary.
Summary of the invention
The object of the invention is to overcome the deficiencies in the prior art, propose a kind of method for designing of 500kV transmission line composite insulator parallel connection gaps, substantially increase power supply reliability.
For achieving the above object, technical scheme provided by the present invention is: a kind of method for designing of 500kV transmission line composite insulator parallel connection gaps, comprises the following steps:
1) determine that parallel connection gaps recruits the shape of arc electrode
Recruit the citation form of arc electrode to be divided into two classes: clavate and annular, the former is in order to improve the Electric Field Distribution of termination, prevents rod end scaling loss too fast, termination can be designed to bead or erietiform; The latter is to obtain significantly all pressure effects and protecting insulator preferably;
2) determine that parallel connection gaps recruits the material of arc electrode
The arc burning characteristic of parallel connection gaps trick arc electrode is the deciding factor of selection material, test shows, when condition is identical, the speed of arc motion only depends on material, and adopt the movement velocity of electric arc on Steel material electrode than adopting and aluminum exceeds 50%, copper is then identical with the situation of aluminium, the hear rate of aluminium is more much higher than steel, under same thermal stress, the position that Different electrodes burns at arc root, the metal loss of aluminium is higher than steel 4 ~ 5 times.At inter space device rod used or when managing measure-alike, its mechanical strength is directly proportional to the strength of materials, aluminium matter inter space device only just can reach the stability identical with steel inter space device when adopting larger size, consider anticorrosion needs, hot-galvanized steel makes overhead circuit parallel gap to recruit the most suitable material of arc electrode;
3) determine that parallel connection gaps recruits the interface of arc electrode
Parallel connection gaps should repeatedly action and not damaging, and this just requires that it has certain thermal stability.Recruit the cross section of arc electrode to determine its thermal stability, the selection in cross section affects by system short-circuit circuit size and the duration of short-circuit.Recruit the smallest cross-sectional of arc electrode to can refer to the cross section requirement met needed for the heat-stable entertoxin of earthing device, and leave certain nargin.
4) physical dimension of parallel connection gaps is determined
For reducing audible noise and improving corona characteristic, the physical dimension of parallel connection gaps need calculate in conjunction with the distribution of insulator surrounding electric field or visible corona test is determined jointly, makes it satisfied not corona and the condition of uniform electric field distribution.
4.1) the parallel connection gaps clearance distance adaptive setting under lightning impulse overvoltage
Parallel connection gaps electrode gap puncture voltage during employing 1.2/50us standard lightning wave impulse and insulator string flashover voltage are respectively as maximum overvoltage, withstand voltage; The time of the breakdown needs in gap is relevant with these factors of structure in voltage pattern, gap, and therefore this time has unpredictable contingency, and this factor just makes electrode gap puncture rule will to be found by a large amount of statistics and conclude;
Suppose u
b50for arcing gap is at lightning impulse 50% discharge voltage, u
j50for lightning impulse 50% discharge voltage of insulator string, σ is standard deviation, then can be obtained by experiment experience: u
b50(1+3 σ)=u
j50(1-3 σ);
The insulator string of 500kV overhead transmission line has 25 usually, conventional XP-7 type porcelain cap and pin insulator string is long is 438mm, under consulting positive polarity lightning impulse voltage, insulator string puncture voltage is released with its length curve figure, line insulator string lightning impulse 50% discharge voltage u
j50=365.7kV, obtains according to formulae discovery, u
b50=305.4kV;
Again according to the calculating standard of recruiting arc gap, formula is as follows:
U
b50＝550H+80
Wherein U
b50for lightning impulse breakdown voltage, unit kV; H is parallel connection gaps clearance distance unit is m;
Release U
b50during=305.4kV, parallel connection gaps clearance distance H=410mm, this is the maximum clearance distance of parallel connection gaps under thunderbolt;
4.2) the parallel connection gaps distance adaptive setting under switching overvoltage
When the unexpected change due to running status in power system operation, the mutual conversion of electromagnetic energy between system internal inductance and capacity cell can be caused, cause concussive transient process, thus there will be on some equipment or local line and be several times as much as the superpotential switching overvoltage of power-frequency voltage.The standard switching impulse of usual employing 250/2500us calculates parallel connection gaps distance, and test shows, switching impulse 50% discharge voltage of parallel connection gaps is higher by 17.6% than the maximum switching overvoltage of system;
According to the calculating standard of above-mentioned parallel connection gaps, can learn: the maximum switching overvoltage of 500kV system is 1900kV, when release gap operating impact flashover voltage is 2234kV, arcing horn clearance distance H=272mm, therefore the minimum clearance distance of arcing horn should be more than or equal to 272mm;
4.3) determination of final parallel connection gaps distance
Parallel connection gaps distance adaptive setting result under comprehensive above-mentioned lightning impulse voltage and operating impulse voltage, parallel connection gaps is meeting under line design requirement, its maximum clearance distance is 410mm, minimum clearance distance is 272mm, therefore parallel connection gaps spacing should in the scope of (272,410) mm;
5) the electric property test of parallel connection gaps
5.1) lightning impulse flashover voltage and voltage-second characteristic test
After parallel connection clearance device is installed, lightning impulse 50% discharge voltage and lightning impulse volt-second characteristic reduce 15% ~ 20%, this is mainly because parallel connection clearance device reduces insulation distance, in addition, parallel connection gaps end is bulb, internal field is caused to distort, discharge voltage can be made to decrease, between clearance distance and lightning impulse 50% discharge voltage value, there is good linear relationship, the lightning impulse voltage-time curve of each parallel connection gaps is all under the voltage-time curve of composite insulator, parallel connection gaps can play the effect protecting composite insulator under lightning overvoltage,
5.2) visual corona and radio interference test
Regulation test voltage 87.6kV is greater than when industrial frequency experiment voltage is elevated to 100kV, the upper and lower electrode of parallel connection gaps has not yet to see visual corona, the visual corona performance of parallel connection gaps meets national standard requirement, in the test of radio interference characteristic, regulation test voltage 87.6kV is greater than when industrial frequency experiment voltage is elevated to 100kV, the radio interference voltage of used in composite insulator parallel connection gaps under 1MHz is respectively 126 and 141 μ V, be less than 1000 μ V settings, the radio interference performance of known parallel connection gaps meets national standard requirement;
5.3) power frequency arc arcing attribute testing
After power frequency heavy-current arcing attribute testing demonstrates line insulator lightning stroke flashover, whether the electric arc that follow-up power frequency short circuit current produces can be directed on parallel connection clearance device, and whether electric arc can be fixed on the bulb position burning of parallel connection clearance device, thus make insulator string avoid calcination, analog conducting wire has the vestige of arc erosion, electric arc is described to power supply movement outside under electrodynamic effect, result of the test shows, designed 500kV parallel connection clearance device meets design requirement.
Compared with prior art, tool has the following advantages and beneficial effect in the present invention:
The present invention proposes a kind of parallel connection gaps design pattern based on ANSYS emulation; change ring diameter, ring body radius, end points bulb diameter, cover into parameters such as the degree of depth; analyze the distribution of parallel connection gaps and insulator surrounding electric field intensity; select all to press the parallel connection gaps style of best performance to be styles design, be particularly suitable for designing all press of good performance, lead the fast and 500kV transmission line composite insulator parallel connection gaps that protected effect is good of arc speed.
Accompanying drawing explanation
Fig. 1 is axle center place electric field and the graph of a relation covered into change in depth.
Fig. 2 is that 80mm place enters the variation diagram of degree of depth voltage with cover.
Fig. 3 is ring footpath schematic diagram for a change.
The electric field intensity map at 80mm place when Fig. 4 is caliber change.
The voltage pattern at 80mm place when Fig. 5 is caliber change.
Fig. 6 is a type 500kV parallel connection gaps pattern diagram of design.
Fig. 7 is the another kind of type 500kV parallel connection gaps pattern diagram of design.
Embodiment
Below in conjunction with specific embodiment, the invention will be further described.
The method for designing of 500kV transmission line composite insulator parallel connection gaps of the present invention, comprises the following steps:
1) determine that parallel connection gaps recruits the shape of arc electrode
This is designed to the parallel connection gaps design of 500kV Composite Insulators, in order to the sub-surrounding electric field distribution of uniform insulation, adopts annular design.
2) determine that parallel connection gaps recruits the material of arc electrode
Analysis shows, it is faster that steel leads arc speed than aluminium, and Corrosion Protection is better, so choose steel parallel connection gaps bulk material.
3) determine that parallel connection gaps recruits the interface of arc electrode
When selecting interface, under the condition meeting thermal stability, and choose the nargin of 10%.
4) physical dimension of parallel connection gaps is determined
When selecting the physical dimension of parallel connection gaps, mainly comprise parallel connection gaps spacing also to claim to cover into the degree of depth, parallel connection gaps circle diameter, ring body radius, starting rod extension elongation, height and bulb diameter etc., analyze known, parallel connection gaps spacing is (272,410) in the scope of mm, the selection of other parameters then meeting the distribution of uniform insulation string surrounding electric field and suppress corona to produce basis on preferentially choose.
5) the electric property test of parallel connection gaps
After parallel connection gaps has designed, need to carry out electric performance test to it, mainly comprise lightning impulse flashover voltage and voltage-second characteristic test, visual corona and radio interference test and power frequency arc arcing attribute testing three kinds of experimental tests, can drop into during Practical Project runs after meeting the demands.
Our selection of composition graphs 1 to Fig. 7 to parallel connection gaps physical dimension is below specifically described, and its situation is as follows:
1) parallel connection gaps spacing
As shown in Figure 1, along with cover enters the continuous increase of the degree of depth, the impact of grading ring on link place is more and more weak.When the degree of depth reaches 489mm, the electric field of junction comes back to cover and enters degree of depth 189mm, and namely shielding depth is 0mm.Overall trend is that along with the increase of the grading ring degree of depth, the field intensity of link place can reduce, and in a segment distance below, electric field still presents downward trend.As shown in Figure 2, along with cover enters the increase of the degree of depth, when 80mm path position magnitude of voltage starts, gap is comparatively large, but finally identical.Analyzed pattern is known, and minimum for starting during installing grading ring, the maximum reached after rising is also minimum, and this is owing to not having grading ring, also just without second locations of high pressure, so the overall numerical value presented is all less.Therefore entering the increase of the degree of depth along with cover, the second locations of high pressure is more and more less on the impact started most, and peak value is also reduction gradually.
To sum up, 339mm and 389mm cover is chosen if the degree of depth is as the basis of next step simulation analysis.
2) parallel connection gaps circle diameter and ring body radius
In above-mentioned analysis, obtain conclusion and can improve electric field around insulator and voltage's distribiuting preferably at the grading ring of 339mm position and 389mm position.On this basis, ring footpath is changed, choose axle center equally and apart from the path of axle center 80mm two place as analysis, progressively change ring footpath, numerical value is set to 185mm respectively, 250mm, 285mm, 385mm, 485mm carry out simulation analysis in this position, five places, and emulation schematic diagram as shown in Figure 3.
The electric field reaction at axle center place be the electric field conditions of plug, choose 80mm position, analyze when changing in ring footpath, the Electric Field Distribution of lower end insulator umbrella makes image, and as shown in Figure 4, when the ring footpath of grading ring changes, the minimum value dropped to of electric field becomes greatly.Due to the change in ring footpath, weakening gradually when electric field distributes in atmosphere, therefore the electric field value of same position is more and more less, what the electric field of same position was subject to lower end gold utensil affects grow, therefore presenting grading ring ring footpath more hour, the electric field value starting same position is most less.Along with the increase of distance, the impact of lower end gold utensil is more and more weak, and the impact in ring footpath also diminishes gradually, finally presents place, the phenomenon that the last amplitude of all curves is close.
When changing the ring footpath of grading ring, choose the voltage data of 80mm position, make image, respectively as shown in Figure 5.When changing ring footpath, the distribution of voltage very close, overall trend is the increase along with grading ring ring footpath, and the voltage on path can increase gradually; But can be found to there is a particular curve in the picture by enlarged image, when namely ring footpath is 250mm, overall voltage is not than the height of 185mm, low on the contrary.In order to debug, carry out repetition simulation analysis to the setting in 250mm ring footpath, result is still identical.This is consistent with the target having minimum average B configuration voltage that we find on full skirt.
To sum up analyze known, when changing the ring footpath of grading ring, before the electric field of several insulators can decline rapidly, the object better protecting insulator can be realized; The change of voltage and the relation in ring footpath are little, but the reversal occurred in the change of voltage, and when 250mm, voltage's distribiuting is no longer increase, but is reduced to a region also lower than 185mm, and this is our extreme point of finding just.Determine through comparative analysis, superior than other positions of the voltage's distribiuting of 250mm position, therefore choose the basis that 250mm position emulates as next step.
3) parallel connection gaps circle diameter
Analytical procedure similar 1) and 2) shown in, can be drawn by analysis result: when changing caliber, the electric field curve at 70mm place is obviously better than other curves, obviously can improve the electric field environment residing for full skirt and plug, although voltage curve slightly slightly with other curves, but whole discrepancy is little, therefore 70mm caliber is adopted to carry out next step simulation analysis.
4) starting rod extension elongation is on the impact of Electric Field Distribution
On the basis emulated above, progressively change the length that parallel connection gaps stretches out.Analytical procedure similar 1) and 2) shown in, comparative analysis length is respectively 100, and 200,300,500 each and every one numerical value of (mm) five are analyzed, and study the change along with length, the trend of the Electric Field Distribution change around insulator.
By analyzing the electric field data obtaining axle center and 80mm position, make image, as can be seen from Electric Field Distribution image, when extension elongation increases, the Electric Field Distribution of insulator surrounding is optimized and improves.Possible cause is high strong field on the top of extension elongation, and along with the increase of distance, the numerical value of field decay increases, and finally presents distance far away, the situation that the Electric Field Distribution around insulator is more superior.But consider in Practical Project, extension elongation can not unconfined length.Because along with the elongation of parallel connection gaps, the center of inter space device is moved to outside gradually, is unfavorable for installing and long-term operation.Person of outstanding talent's teams experiment data more than reference Qinhua Univ., Beijing, select outreach to be set to 200mm, ensure to obtain desirable effect when testing.
5) starting rod stretches out highly on the impact of Electric Field Distribution
In Practical Project; parallel connection gaps often will exceed a segment distance than cross section, grading ring place; the object of such design is the electric field structure in order to form a class rod type within the cleft; in high voltage and heavy current through transmission line; make the disruptive field intensity of parallel connection gaps lower than disruptive field intensity around insulator, one plays the effect protecting insulator.
Design parallel connection gaps height problem time, do not install bulb additional, so the Electric Field Distribution on top can due to point effect but Electric Field Distribution is very uneven, this point is beyond one's reach carrying out chamfering operation.On the basis emulated above, progressively change starting rod and stretch out height.Analytical procedure similar 1) and 2) shown in, progressively change the height that starting rod stretches out, obtain the electric field data on axle center and 80mm path, make image.
When the highly increase of stretching out of parallel connection gaps is that the electric field of axle center and 80mm position can significantly improve.But along with the change of short circuit distance is large, the below of voltage-time curve at insulator of device can be made, and then avoid insulator by flash burn.The negative effect meanwhile brought time, when the voltage increases, the protective margin of parallel connection gaps can obviously reduce.
What emulation adopted is short circuit distance is each up and down 10% of dry arcing distance, and in conjunction with the data analysis of the scholars such as Yang Qing, insulator can be protected well in gap now.Image also shows, when 200mm, although the electric field strength of shaft core position and 80mm position, distribution on former insulators is all better than other height position data, but due to when the height stretched out is more than 100mm, the field intensity of clearance surface more than 30kv/cm, can there will be the phenomenon of bloom, therefore selects 100mm height as the short circuit height of parallel connection gaps.
6) impact of Probe-radius on Electric Field Distribution is stretched out
Found by the seizure of high-speed motion picture camera in actual experiment, arc burning can move as bulb position gradually, and has the longest time of staying on bulb.Electric arc is be subject to electric field force in motion, the acting in conjunction of electromagnetic force and heat buoyancy.The radius changing bulb can affect the field intensity difference on parallel connection gaps surface, accelerates the movement velocity of electric arc in clearance surface.Meanwhile, the design of bulb also can cause small impact to the Electric Field Distribution around insulator umbrella.In the emulation of this section, analytical procedure similar 1) and 2) shown in, progressively change the numerical value stretching out Probe-radius, be set to 40mm50mm60mm tri-groups of data analyses respectively, the electric field data obtaining axle center and 80mm path is analyzed.
When Probe-radius changes, the electric field around insulator umbrella is not according to fixing Long-term change trend.Overall trend rises after formerly declining, and reaches minimum electric field value at 50mm place.In conjunction with the experimental data of remaining person of outstanding talent team, after Probe-radius reaches 50mm, the electric field strength on bulb can be lower than the electric field value on grading ring, is unfavorable for the movement of electric arc, therefore adopt the 40mm that there is electric field difference, analyzes numerical value as next step.And in Practical Project, Probe-radius can not be too large, because when adding Probe-radius, overall quality can increase, and then increases the load of insulator, so 40mm is more suitable.
To sum up, the simulation models such as insulator, parallel connection gaps and surrounding air are built based on Ansys, consider that parallel connection gaps spacing, circle diameter, annulus ring body diameter, starting rod extension elongation, starting rod stretch out height and starting rod and stretch out the distribution to 500kV composite insulator surrounding electric field intensity such as bulb diameter, choose optimized parameter as shown in table 1 below.
The every Optimal Parameters of table 1 parallel connection gaps
Change on the basis of parameter at table 1 optimum, design as Fig. 6,7 these two type 500kV parallel connection gaps patterns.
The examples of implementation of the above are only the preferred embodiment of the present invention, not limit practical range of the present invention with this, therefore the change that all shapes according to the present invention, principle are done, all should be encompassed in protection scope of the present invention.
Claims (1)
1. a method for designing for 500kV transmission line composite insulator parallel connection gaps, is characterized in that, comprises the following steps:
1) determine that parallel connection gaps recruits the shape of arc electrode
1.1) recruit the citation form of arc electrode to be divided into two classes: clavate and annular, the former is in order to improve the Electric Field Distribution of termination, prevents rod end scaling loss too fast, termination can be designed to bead or erietiform; The latter is to obtain significantly all pressure effects and protecting insulator preferably;
1.2) for composite insulator, adopt parallel connection gaps, not only need to consider protection insulator and wire are from power frequency arc calcination, also should consider whether meet visual corona and radio interference requirement, whether improve insulator string voltage's distribiuting;
1.3) arc electrode design is recruited to be open annular the high-low pressure of linear string;
2) determine that parallel connection gaps recruits the material of arc electrode
The arc burning characteristic of parallel connection gaps trick arc electrode is the deciding factor of selection material, at present, the conventional material of line hardware has steel, copper, aluminium, if electrode sections is constant, when experimental condition is identical, the speed of arc motion only depends on material, adopting the movement velocity of electric arc on Steel material electrode than adopting, aluminum exceeds 50%, copper is then identical with the situation of aluminium, the hear rate of aluminium is more much higher than steel, under same thermal stress, the position that Different electrodes burns at arc root, the metal loss of aluminium is higher than steel 4 ~ 5 times, in the position that arc root burns, the overwhelming majority in the material of loss is not proper burning, but dished out in the form of granules, in the short circuit test of aluminium electrode, a large amount of materials lost is had to be scattered on floor with the form of aluminium oxide after finding test,
At inter space device rod used or when managing measure-alike, its mechanical strength is directly proportional to the strength of materials, aluminium matter inter space device only just can reach the stability identical with steel inter space device when adopting larger size, consider anticorrosion needs, hot-galvanized steel makes overhead circuit parallel gap to recruit the most suitable material of arc electrode;
3) determine that parallel connection gaps recruits the interface of arc electrode
Parallel connection gaps should repeatedly action and not damaging, this just requires that it has certain thermal stability, the cross section of arc electrode is recruited to determine its thermal stability, the selection in cross section affects by system short-circuit circuit size and the duration of short-circuit, if thunderbolt makes from the shaft tower flashover close to transformer station, then short circuit current and bus place short circuit current are more or less the same, if install parallel connection gaps herein, recruit arc electrode should meet the thermally-stabilised requirement of short circuit current, the smallest cross-sectional of arc electrode is recruited to can refer to the cross section requirement met needed for the heat-stable entertoxin of earthing device, need in the fabrication process owing to all pressing arcing ring to bore installing hole, a part of metal can be lost in drill hole, also thermally-stabilised requirement can be met for making drill hole, certain nargin need be left, and the electric arc on trick arc electrode is due to heat power, high-speed motion under electrodynamic action, mechanicals efforts can be had to trick arc electrode, it is very necessary for leaving nargin,
4) physical dimension of parallel connection gaps is determined
For reducing audible noise and improving corona characteristic, the lower parallel connection gaps of parallel connection gaps and on high-tension side position need be determined in conjunction with electric Field Calculation or visible corona test, and with reference to the result of study that during parallel connection gaps design, lightning outage rate calculates, Electric Field Distribution calculates;
4.1) the parallel connection gaps clearance distance adaptive setting under lightning impulse overvoltage
To the waveform regulation of standard lightning wave be:
T
1＝1.2(1+30％)μs，T
2＝50(1+20％)μs
Standard lightning wave for opposed polarity can be expressed as:
+ 1.2/50 μ s or-1.2/50 μ s
Therefore parallel connection gaps electrode gap puncture voltage during employing+1.2/50 μ s standard lightning wave impulse and insulator string flashover voltage are respectively as maximum overvoltage, withstand voltage;
There is minimum Static Breakdown Voltage in each gap, namely long duration of action can make the lowest amplitude voltage of gap breakdown on electrode, ensure breakdown to gap, applying voltage just must be made to be greater than minimum quiescent voltage, apply voltage simultaneously and also will maintain required time to ensure completing of electric discharge evolution, i.e. interspike intervals;
The time of the breakdown needs in gap is relevant with these factors of structure in voltage pattern, gap, and therefore this time has unpredictable contingency, and this factor just makes electrode gap puncture rule will to be found by a large amount of statistics and conclude;
Suppose u
b50for arcing gap is at lightning impulse 50% discharge voltage, u
j50for lightning impulse 50% discharge voltage of insulator string, σ is standard deviation, then can be obtained by experiment experience: u
b50(1+3 σ)=u
j50(1-3 σ);
The insulator string of 500kV overhead transmission line has 25 usually, conventional XP-7 type porcelain cap and pin insulator string is long is 438mm, under consulting positive polarity lightning impulse voltage, insulator string puncture voltage is released with its length curve figure, line insulator string lightning impulse 50% discharge voltage u
j50=365.7kV, obtains according to formulae discovery, u
b50=305.4kV;
Again according to the calculating standard of recruiting arc gap, formula is as follows:
U
b50＝550H+80
Wherein U
b50for lightning impulse breakdown voltage, unit kV; H is parallel connection gaps clearance distance unit is m;
Release U
b50during=305.4kV, parallel connection gaps clearance distance H=410mm, this is the maximum clearance distance of parallel connection gaps under thunderbolt;
4.2) the parallel connection gaps clearance distance adaptive setting under switching overvoltage
In electric power networks, there is a large amount of inductance, capacitor element, inductance component includes generator, transformer, instrument transformer, reactor, line inductance, arc suppression coil; Capacitor element includes and series capacitor bank in parallel for reactive power compensation, line conductor direct-to-ground capacitance and circuit capacitive coupling, the stray capacitance of high-tension apparatus; When the unexpected change due to running status in power system operation, the mutual conversion of electromagnetic energy between system internal inductance and capacity cell can be caused, cause concussive transient process, thus there will be on some equipment or local line and be several times as much as power-frequency voltage overvoltage, be called switching overvoltage;
Switching overvoltage has the higher-order of oscillation, heavy damping, dyingout time short temporary overvoltage, the waveform similarity of waveform under switching overvoltage and under power frequency condition of electrode gap puncture voltage, insulator string flashover voltage, rush coefficient carry out mirror operation impulse sparkover voltage so operation can be multiplied by with power-frequency sparkover voltage, 250/2500 shock wave is adopted to calculate parallel connection gaps clearance distance, by experiment experience, the switching impulse 50% electric discharge pressure of parallel connection gaps is higher by 17.6% than the maximum switching overvoltage of system;
Again according to the calculating standard of above-mentioned parallel connection gaps, can learn: the maximum switching overvoltage of 500kV system is 1900kV, release gap operating impact flashover voltage U
b50during=2234kV, arcing horn clearance distance H=272mm, this is the minimum clearance distance of arcing horn under thunderbolt;
4.3) determination of final parallel connection gaps clearance distance
Parallel connection gaps clearance distance adaptive setting result under comprehensive above-mentioned lightning impulse voltage and operating impulse voltage, the known defencive function wanted designed by parallel connection gaps, its maximum clearance distance is 410mm, minimum clearance is apart from being 272mm, and the parallel connection gaps therefore met design requirement two electrode tip spacing must between ultimate range and minimum range;
5) the electric property test of parallel connection gaps
5.1) lightning impulse flashover voltage and voltage-second characteristic test
After parallel connection clearance device is installed, lightning impulse 50% discharge voltage and lightning impulse volt-second characteristic reduce 15% ~ 20%, this is mainly because parallel connection clearance device reduces insulation distance, in addition, parallel connection gaps end is bulb, internal field is caused to distort, discharge voltage can be made to decrease, between clearance distance and lightning impulse 50% discharge voltage value, there is good linear relationship, the lightning impulse voltage-time curve of each parallel connection gaps is all under the voltage-time curve of composite insulator, parallel connection gaps can play the effect protecting composite insulator under lightning overvoltage,
5.2) visual corona and radio interference test
Regulation test voltage 87.6kV is greater than when industrial frequency experiment voltage is elevated to 100kV, the upper and lower electrode of parallel connection gaps has not yet to see visual corona, the visual corona performance of parallel connection gaps meets national standard requirement, in the test of radio interference characteristic, regulation test voltage 87.6kV is greater than when industrial frequency experiment voltage is elevated to 100kV, the radio interference voltage of used in composite insulator parallel connection gaps under 1MHz is respectively 126 and 141 μ V, be less than 1000 μ V settings, the radio interference performance of known parallel connection gaps meets national standard requirement;
5.3) power frequency arc arcing attribute testing
After power frequency heavy-current arcing attribute testing demonstrates line insulator lightning stroke flashover, whether the electric arc that follow-up power frequency short circuit current produces can be directed on parallel connection clearance device, and whether electric arc can be fixed on the bulb position burning of parallel connection clearance device, thus make insulator string avoid calcination, analog conducting wire has the vestige of arc erosion, electric arc is described to power supply movement outside under electrodynamic effect, result of the test shows, designed 500kV parallel connection clearance device meets design requirement.
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Cited By (9)
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| CN105761856A (en) * | 2016-04-13 | 2016-07-13 | 云南电网有限责任公司电力科学研究院 | Differentiation configuration method for parallel gap electrode |
| CN105976948A (en) * | 2016-04-29 | 2016-09-28 | 国家电网公司 | Anti-bird parallel gap and mounting method thereof |
| CN109001606A (en) * | 2018-09-30 | 2018-12-14 | 国网湖南省电力有限公司 | The test model and application method of a kind of alternate electric discharge of transmission line simulation |
| CN109270415A (en) * | 2018-08-27 | 2019-01-25 | 云南电网有限责任公司电力科学研究院 | The VFTO method of inspection and system of surface of composite insulator pulse accounting rate |
| CN110718859A (en) * | 2019-10-16 | 2020-01-21 | 国网电力科学研究院武汉南瑞有限责任公司 | Method for selecting series gap of line lightning arresters in direct-current transmission system |
| CN111523261A (en) * | 2020-03-19 | 2020-08-11 | 清华大学 | Method and device for determining air gap of smoothing reactor of direct-current power transmission system |
| CN112038015A (en) * | 2020-09-01 | 2020-12-04 | 沈阳工业大学 | Wall bushing of capacitive high-temperature solid electric heat storage device and design method |
| CN112051487A (en) * | 2020-08-17 | 2020-12-08 | 国网湖南省电力有限公司 | Icing flashover characteristic test method for multiple series-parallel insulators of power transmission line |
| CN113178853A (en) * | 2021-04-29 | 2021-07-27 | 广东电网有限责任公司电力科学研究院 | Overvoltage protection system for lightning invasion waves on transformer substation line side |
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Cited By (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105761856A (en) * | 2016-04-13 | 2016-07-13 | 云南电网有限责任公司电力科学研究院 | Differentiation configuration method for parallel gap electrode |
| CN105976948A (en) * | 2016-04-29 | 2016-09-28 | 国家电网公司 | Anti-bird parallel gap and mounting method thereof |
| CN109270415A (en) * | 2018-08-27 | 2019-01-25 | 云南电网有限责任公司电力科学研究院 | The VFTO method of inspection and system of surface of composite insulator pulse accounting rate |
| CN109001606A (en) * | 2018-09-30 | 2018-12-14 | 国网湖南省电力有限公司 | The test model and application method of a kind of alternate electric discharge of transmission line simulation |
| CN110718859A (en) * | 2019-10-16 | 2020-01-21 | 国网电力科学研究院武汉南瑞有限责任公司 | Method for selecting series gap of line lightning arresters in direct-current transmission system |
| CN111523261A (en) * | 2020-03-19 | 2020-08-11 | 清华大学 | Method and device for determining air gap of smoothing reactor of direct-current power transmission system |
| CN111523261B (en) * | 2020-03-19 | 2024-02-09 | 清华大学 | Method and device for determining air gap of smoothing reactor of direct-current transmission system |
| CN112051487A (en) * | 2020-08-17 | 2020-12-08 | 国网湖南省电力有限公司 | Icing flashover characteristic test method for multiple series-parallel insulators of power transmission line |
| CN112051487B (en) * | 2020-08-17 | 2022-03-29 | 国网湖南省电力有限公司 | Icing flashover characteristic test method for multiple series-parallel insulators of power transmission line |
| CN112038015A (en) * | 2020-09-01 | 2020-12-04 | 沈阳工业大学 | Wall bushing of capacitive high-temperature solid electric heat storage device and design method |
| CN112038015B (en) * | 2020-09-01 | 2022-06-03 | 沈阳工业大学 | Design method of wall bushing of capacitive high-temperature solid electric heat storage device |
| CN113178853A (en) * | 2021-04-29 | 2021-07-27 | 广东电网有限责任公司电力科学研究院 | Overvoltage protection system for lightning invasion waves on transformer substation line side |
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