JP5637397B2 - DC arc test simulation method, simulator and simulation software for overhead ground wire - Google Patents

Description

  The present invention relates to a DC arc test simulation method, simulator, and simulation software for an overhead ground wire, and is particularly useful when applied to verify the melting characteristics of an overhead ground wire by simulating a direct current arc test that simulates lightning strikes. It is.

  An overhead ground wire (hereinafter referred to as GW) is installed above the overhead power transmission line for the purpose of preventing direct lightning strikes on the overhead power transmission line and preventing reverse flashover from the steel tower to the electric wire during lightning strikes. This type of overhead ground wire is designed on the assumption that it will receive direct lightning strikes, but for lightning strikes that have a large current value due to direct lightning strikes and a long duration, the wires of the overhead ground wire will melt. It has been reported. In addition, an optical fiber composite aerial ground wire (hereinafter referred to as OPGW) that was developed to transmit various types of monitoring system information by incorporating an optical fiber together with a steel wire with mechanical strength. Have recently been introduced in large quantities into the transmission system. When this OPGW is also subjected to a lightning strike, the strands may melt.

  Against this background, in addition to preventing direct lightning strikes to power transmission lines, OPGW, which plays a role in system information transmission, etc., needs to examine its fusing prevention measures in particular. It is important to elucidate.

  For this reason, a DC arc test simulating a lightning strike on an overhead ground wire has been performed. According to the lightning observation examples so far, the current peak value is about 1 to 100 kA, the duration is about 10 to 200,000 μs (200 ms), and the amount of electricity is about 0.1 to 1,000 C. Wide range of values. In addition, most summer lightnings are negative, whereas winter lightnings are about 10-30% positive. On the other hand, there are many combinations of parameters such as the size and number of strands of the overhead ground wire because they are determined according to the usage of the overhead ground wire.

  For this reason, in order to perform the DC arc test of various parameter conditions with respect to many types of overhead ground wires, there is a problem that a large amount of money is required and a long time is required.

  Such a problem can be solved if the simulation method of the DC arc test as described above can be established. However, in order to establish such a simulation method, the effect of heat transfer from the arc to the overhead ground wire is accurately simulated. It is important to

  On the other hand, there are Non-Patent Document 1 as a publicly-known document disclosing a consideration regarding strand melting of an overhead ground wire due to a surge current, and Patent Documents 1 to 3 as publicly-known literatures disclosing techniques related to lightning-resistant electric wires.

JP 05-62552 A Japanese Patent Application Laid-Open No. 07-57544 JP 2008-251267 A

Kito, Mizuno: "Experimental study on wire melting of overhead ground wire by surge current", IEEJ Transactions B, 108, 12, pp.577-584 (1988)

  In Non-Patent Document 1, only the heat transfer amount by electron transport is assumed as the heat transfer amount from the arc to the GW (see equations (1) and (2) on page 581). Moreover, in patent document 1-patent document 3, it is not mentioned regarding the amount of heat transfer to an overhead ground wire. However, in any case, it is considered that the amount of heat transfer cannot be accurately reflected by assuming only the amount of heat transfer by electron transport.

  Furthermore, in Non-Patent Document 1 and Patent Documents 1 to 3, the melting amount of the overhead ground wire is evaluated as a function of only the passing electricity amount, but it is not sufficient. This is because, in the experimental results so far, even when the passing electricity amount is the same, the melting amount of the overhead ground wire may be different if the arc current is different.

  An object of the present invention is to provide a DC arc test simulation method, a simulator, and simulation software for simulating a DC arc test performed by simulating a lightning strike on a GW.

The first aspect of the present invention for achieving the above object is as follows:
DC arc test for an overhead ground wire that simulates a lightning strike by simulating a lightning strike by supplying an arc current from a DC arc to an overhead ground wire that is fixed at both ends with a predetermined tension applied The simulation method of
The total amount of heat transferred to the overhead ground wire by the direct current arc, the arc current of the direct current arc supplied to the overhead ground wire, the arc conditions including the supply time of the arc current, the size of the overhead ground wire and the strand This is a DC arc test simulation method for an overhead ground wire, which is calculated by the sum of the heat transfer amount by electron transport and the heat transfer amount by convective heat transfer based on the overhead ground wire condition including the material of the ground.

  According to this aspect, the total heat transfer amount to the overhead ground wire can be considered not only the heat transfer amount by electron transport but also the heat transfer amount by convective heat transfer. That is, in the past, the evaluation was mainly based on the time integration of the arc current (the amount of electricity passed), but according to this aspect, the evaluation is based on the melting amount based on the arc current, and an accurate evaluation is made accordingly. Can do. This was confirmed by a predetermined DC arc experiment as will be described later.

The second aspect of the present invention is:
In the DC arc test simulation method described in the first aspect,
Calculating the relationship between the time until the aerial ground wire is melted by a predetermined amount and the arc current based on the total heat transfer amount to obtain the melting characteristics of the aerial ground wire represented by the relationship between the time and the arc current. It is in the simulation method of the DC arc test for the characteristic overhead ground wire.

  According to this aspect, it is possible to accurately simulate the relationship between the arc current and the time until the predetermined amount of the overhead ground wire melts.

The third embodiment of the present invention
In the simulation method of the DC arc test for the overhead ground wire described in the first or second aspect,
The amount of heat transfer by the convective heat transfer is based on an arc jet ejected from the counter electrode opposed to the overhead ground wire through a gap toward the overhead ground wire, and has a predetermined heat transfer coefficient, While obtaining by the product of the heat transfer area which is the area of the area where the DC arc is in contact with the outer peripheral surface of the overhead ground wire and the temperature difference between the DC arc and the surface of the overhead ground wire,
In the simulation method of the DC arc test for the overhead ground wire, the heat transfer area is changed depending on the arc current of the DC arc and the material of the overhead ground wire.

  According to this aspect, the amount of heat transfer by convective heat conduction is obtained from the heat transfer coefficient, heat transfer area, and temperature difference, and the heat transfer area is changed depending on the arc current of the DC arc and the material of the overhead ground wire. By using the accurate heat transfer area as a parameter that varies depending on the arc current and the material of the overhead ground wire, it is possible to obtain an accurate melting characteristic accordingly.

The fourth aspect of the present invention is:
A DC arc test simulator for an overhead ground wire for simulating a direct current arc test simulating a lightning strike by bringing a DC arc into contact with an overhead ground wire fixed at both ends with a predetermined tension applied. ,
Parameter setting to set the arc current including the arc current of the DC arc supplied to the sample ground wire, the arc current supply time, and the size of the overhead wire and the material of the wire And
Based on the parameters set in the parameter setting unit, the amount of heat transferred by electron transport and the amount of heat transferred by convective heat transfer are calculated, and both are added to calculate the total amount of heat transferred to the overhead ground wire by the DC arc. And a direct current arc test simulator for an overhead ground wire.

  According to this aspect, the total heat transfer amount to the overhead ground wire can be considered not only the heat transfer amount by electron transport but also the heat transfer amount by convective heat transfer. That is, in the past, the evaluation was mainly based on the time integration of the arc current (the amount of electricity passed). However, according to this aspect, the evaluation is based on the melting amount based on the arc current, and an accurate melting characteristic is obtained accordingly. be able to.

According to a fifth aspect of the present invention,
In the simulator of the DC arc test for the overhead ground wire described in the fourth aspect,
The calculation unit calculates a relationship between the arc current and a time until the overhead ground wire is melted by a predetermined amount based on the total heat transfer amount, and melts the overhead ground wire represented by the relationship between the time and the arc current. It is a simulator for DC arc test on overhead ground wire, which is characterized by characteristics.

  According to this aspect, it is possible to accurately reproduce the relationship between the arc current and the time until the overhead ground wire melts by a predetermined amount.

The sixth aspect of the present invention is:
In the simulator of the DC arc test for the overhead ground wire described in the fourth or fifth aspect,
The calculation unit is based on an arc jet ejected from the counter electrode toward the aerial ground wire, and the heat transfer amount due to the convective heat transfer is determined at a predetermined heat transfer coefficient, the outer peripheral surface of the aerial ground wire. While calculating by the product of the heat transfer area which is the area of the area where the DC arc is in contact and the temperature difference between the DC arc and the surface of the overhead ground wire,
The heat transfer area is calculated as a function of the arc current and the material of the overhead ground wire, and is in a DC arc test simulator for the overhead ground wire.

  According to this aspect, the amount of heat transfer by convective heat conduction is obtained from the heat transfer coefficient, heat transfer area, and temperature difference, and the heat transfer area is changed depending on the arc current of the DC arc and the material of the overhead ground wire. By using the accurate heat transfer area as a parameter that varies depending on the arc current and the material of the overhead ground wire, it is possible to obtain an accurate melting characteristic accordingly.

The seventh aspect of the present invention is
DC arc test for an overhead ground wire that simulates a lightning strike by simulating a lightning strike by supplying an arc current from a DC arc to an overhead ground wire that is fixed at both ends with a predetermined tension applied Simulation software,
Heat transfer amount and convective heat transfer by electron transport based on the arc conditions including the set direct current arc current, the arc current supply time, and the overhead ground wire conditions including the size of the overhead ground wire and the type of wire. A step of calculating the amount of heat transfer due to,
A step of calculating a total amount of heat transfer to the overhead ground wire by the DC arc by adding the amount of heat transfer by electron transport and the heat transfer amount by convective heat transfer; Located in arc test simulation software.

  According to this aspect, based on the set arc conditions and overhead ground wire conditions, the total heat transfer amount to the overhead ground wire is calculated in consideration of not only the heat transfer amount by electron transport but also the heat transfer amount by convective heat transfer. It becomes software to do. That is, in the past, the evaluation was mainly based on the time integral of the arc current (the amount of electricity passed). However, according to this aspect, the evaluation is based on the melting amount based on the arc current, and an accurate evaluation can be made accordingly. Can be performed.

  According to the present invention, by considering the amount of heat transfer by convective heat transfer, it is possible not only to reproduce the experimental result that the melting amount of the overhead ground wire depends not only on the passing electricity amount but also on the arc current, as well as various arcs. Since simulations can be performed in consideration of conditions and overhead ground wire conditions, rational execution of DC arc tests, optimization of overhead ground wire design and reduction of development costs, support when considering application to actual lines, etc. Can greatly contribute to. By the way, in order to grasp the melting characteristics during lightning strikes on overhead ground wires, it is necessary to perform DC arc tests on various types of overhead ground wires, which requires a large amount of cost. It becomes.

It is explanatory drawing which shows notionally the test apparatus for performing the direct-current arc test which simulated the lightning strike. It is a flowchart which shows the general | schematic procedure of the simulation method which concerns on this Embodiment. It is a block diagram which shows the simulator which concerns on embodiment of this invention. It is sectional drawing (a) which shows an example of actual OPGW, and sectional drawing (b) of OPGW which simulated this. It is sectional drawing (a) which shows the other example of actual OPGW, and sectional drawing (b) of OPGW which simulated this. It is explanatory drawing which shows the various aspects of the arc which contacts OPGW. It is a graph which shows an example of the arc current-time characteristic by the calculation result in the simulator which concerns on embodiment of this invention with an experimental result. It is a graph which shows the other example of the arc current-time characteristic by the calculation result in the simulator which concerns on embodiment of this invention with an experimental result.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In this embodiment, the case where the sample is OPGW will be described, but the present invention is not limited to this. A normal GW that is not an OPGW may be used.

FIG. 1 is an explanatory diagram conceptually showing a test apparatus for performing a DC arc test simulating lightning strike. As shown in the figure, the test apparatus stretches a thin copper wire between the sample OPGW1 and the counter electrode 2 of the iron round bar connected to the power source on the power application side, and supplies the test current there. Fusing and igniting by energizing. Here, the gap length L _gap between the OPGW 1 and the counter electrode 2 is about 50 to 1500 mm. Further, the OPGW 1 is bridged between the concrete blocks 5 and 6 at both ends with insulators 3 and 4 with substantially the same tension as the actual line. The tension at this time is measured by a tensiometer 7.

A part of the surface of the OPGW 1 is covered with vinyl tapes 9 and 10. This is to suppress the phenomenon that the arc 11 in the vicinity of OPGW 1 formed between the counter electrode 2 and OPGW 1 comes into contact with OPGW 1 to newly form an arc spot and moves in the axial direction of OPGW 1. That is, the exposed portion 12, which is a region where the surface of the OPGW 1 is exposed by winding and insulating the vinyl tapes 9 and 10, is formed between the vinyl tapes 9 and 10. Here, the exposed length L _ex is the length in the axial direction of the exposed portion 12, for example, about 20~40mm are preferred. Further, the current on the ground side is divided almost evenly so that the arc 11 does not easily move in the axial direction of the OPGW 1 due to electromagnetic force. As a power source, a short-circuit generator and a rectifier are used, and a direct current is generated by three-phase full-wave rectification of an alternating current. Note that an arrow DC _A in the figure indicates that the DC power source is connected to the charging side, and DC _C is connected to the ground side of the DC power source.

  FIG. 2 is a flowchart showing a schematic procedure of the simulation method according to the present embodiment. As shown in the figure, in the simulation method according to the present embodiment, arc conditions (arc current, arc duration, polarity, gap length, etc.) and OPGW conditions (OPGW1 size (wire diameter), strand type, By setting the arc number and the OPGW condition, the heat transfer amount and the heat transfer area from the arc 11 to the OPGW 1 are predicted, and the melting amount of the OPGW 1 is calculated. Here, the heat transfer amount is the heat amount of the arc 11 injected from the arc 11 to the OPGW 1, and the heat transfer area is the area of the portion where the arc 11 contacts on the surface of the OPGW 1, and the heat amount of the arc 11 is injected. The area of the region.

FIG. 3 is a block diagram showing a simulator that specifically realizes the simulation method shown in FIG. As shown in the figure, the simulator has a parameter setting unit 21, an arithmetic processing unit 22, and a display unit 23. The parameter setting unit 21 includes an arc condition setting unit 21A and an OGW condition setting unit 21B. The arc condition setting unit 21A has arc conditions such as the arc current I _DC , the time during which the arc current I _DC is supplied, the arc polarity (which simulates the polarity of lightning), and the gap length L _gap. In the OPGW condition setting unit 21B, parameters related to OPGW conditions such as the size (wire diameter) of OPGW1, the type (material) and the number of strands of OPGW1 are set.

  The calculation processing unit 22 includes a heat transfer amount calculation unit 22A, a heat transfer area calculation unit 22B, and a melt amount calculation unit 22C.

The heat transfer amount calculation unit 22A calculates the _total heat transfer amount P _total from the arc 11 to the OPGW 1 based on each parameter set in the parameter setting unit 21. In this embodiment, the _total heat transfer amount P _total is processed as the sum of the heat transfer amount P _ele due to electron transport and the heat transfer amount P _cond due to convective heat transfer. That is, the _total heat transfer amount P _total is expressed by the following formula (1).

The heat transfer amount P _ele in the above formula (1) includes the electrode drop voltage (cathode drop voltage, anode drop voltage), the heat amount due to the work function, and the heat amount due to the enthalpy transport of electrons. Depending on the polarity, the following expressions (2) and (3) are used.

Here, P _c and P _a are the amount of heat caused by the cathode drop voltage V _c and the anode drop voltage V _a , respectively, P _w is the amount of heat caused by the work function V _w , and P _t is the amount of heat caused by the enthalpy transport of electrons. It is. P _c , P _a and P _w are values obtained by multiplying V _c , V _a and V _w by the arc current I _DC , respectively. P _t is expressed by the product of V _t and arc current I _{DC in the} following equation (4).

Here, T _arc is the temperature [K] of the arc near OPGW1.

These various voltage values V _c , V _a , V _w and V _t differ depending on the electrode material and the atmospheric gas. On the other hand, since the outermost layer of OPGW 1 that touches the arc 11 is usually an aluminum-clad steel wire, the various voltage values V _c , V _a , V _w, and V _t are such that the electrode material is aluminum as shown in Table 1. Alternatively, literature values in the case where iron and the atmospheric gas are air can be used.

It should be noted that the above V _t, for example, Document 1 (Iwata, Tanaka, Ikeda, Goda: "50kA head of class temperature characteristics of the arc jet unit in the gap alternating high current arc (Part 2) - the temperature of the arc jet ejected from the iron electrode And energy density-", calculated by the formula (4) in consideration of the dependence of temperature on the current and electrode material reported in the Research Report No. W00026 (2001)).

Here, assuming that a value obtained by dividing P _ele by I _DC is V _ele , V _ele is expressed by the following equations (5) and (6) based on equations (2) and (3).

As shown in Table 1, V _ele calculated using these equations varies depending on the material and polarity of OPGW.

On the other hand, the heat transfer amount P _cond by convective heat transfer in the equation (1) is caused by a high-temperature / high-pressure arc jet injected from the counter electrode (see FIG. 1), and has a heat transfer coefficient h, a heat transfer area _Sh. And the product of the temperature difference between the arc 11 and the surface of the OPGW 1 can be obtained by the following equation (7).

Here, h is a heat transfer coefficient [W / m ² / K]. Specifically, it is expressed as the following formula (8).

Here, κ is the thermal conductivity [W / m / K] of the arc. D is the representative dimension [m] of OPGW1, and here is the diameter of OPGW1. Nu is the Nusselt number and shows a different value depending on the aspect of heat transfer, and various empirical formulas have been proposed. Here, since the arc jet ejected from the counter electrode 2 collides with the cylindrical OPGW 1, “heat transfer by the collision jet” was assumed. In this case, Nu varies depending on conditions such as the gap length L _gap and the diameter d of the counter electrode 2, and is expressed by the following equations (9) and (12) using the Prandtl number Pr and the Reynolds number Re.

  Here, C is represented by the following equations (10) and (11).

  Note that Pr and Re are expressed as follows.

Here, c _p , μ, ρ and v are constant pressure specific heat [J / kg / K], viscosity [kg / m / s], mass density [kg / m ³ ] and flow velocity [m / s], respectively. ]. About these values and (kappa), it can each calculate with reference to the said literature 1.

In the above formula (7), the _{S h} in the heat transfer area ^{[m 2],} the density J _Al arc current I _DC, J _Fe is constant for each material (aluminum (Al) and iron (Fe)) Therefore, as represented by the following formula (15) as a function of arc current I _DC.

That is, in this embodiment, the heat transfer area S _h in the literature 2 (Goda, Iwata, Ikeda, Tanaka: "50kA head of class gap large current arc jet aspects - arc jet diameter and voltage characteristics -", Central Research Institute of Electric Power Report The current density is constant using the arc diameter at the electrode end face of Research Report No. W00034 (2001) (the current densities of the aluminum and iron electrode end faces are 60.0 A / mm ² and 33.8 A / mm ² , respectively) And the area of the exposed portion 12 (see FIG. 1) of OPGW1 is equal to or less. That is, the smaller of the contact area of the arc with the outer peripheral surface of the OPGW 1 and the area of the exposed portion 12 is selected and used.

Further, in the above formula (7), T _OPGW is the temperature of the surface of OPGW1. This is considered to be near the melting point during the arc generation at room temperature (300 K) before the arc is generated, but here it is set to 300 K in order to grasp the maximum value of P _cond . Note that P _cond when _TOPGW is the melting point is about 10 to 20% less than that of 300K. Calculation of heat transfer area S _h based on the above equation (15) in the case of the present embodiment is performed in the heat transfer area calculation unit 22B.

The heat transfer amount calculation unit 22A calculates the heat transfer amount P _ele by electron transport based on the above formulas (2) to (6), and the heat transfer amount P by convective heat transfer based on the above formulas (7) to (14). _cond is calculated, and the _total heat transfer amount _Ptotal is calculated based on Expression (1) as the sum of the two. This is the total amount of heat injected from the arc 11 into the OPGW 1.

Melting amount calculation unit 22C refers to the predetermined parameters set in the parameter setting unit 21, a predetermined melting characteristics by calculating the amount of melting of OPGW31 from information Zenden heat P _total and the heat transfer area S _h Ask. More specifically, the energy required for melting the strand of OPGW31 is the sum of the energy required to rise from room temperature to the melting point and the energy required until full melting after reaching the melting point. Here, the room temperature is 300K. The former can be calculated using the specific heat and mass density of the material of the wire (aluminum, iron). Although the specific heat in this case varies depending on the temperature, in this embodiment, the average value at room temperature and at the melting point is used to simplify the calculation. The latter can be calculated using the mass density of the material of the wire and the latent heat of fusion.

That is, the melting energy density E _m is the melting energy per unit volume is represented by the following formula (16).

Here, E _(Tm-300K) is the energy density required for the strand of OPGW1 to rise from room temperature to the melting point, and E _ml is the latent heat density.

Therefore, if the melting volume of the strand of OPGW1 melted by the arc is V _m (m ³ ), the melting volume V is expressed by the following equation (17).

      Here, Δt is an arc time which is a duration of the arc.

Thus, the set arc time Δt to the parameter setting unit 21, together with the melting energy density _{E m} obtained in the expression (1) P _total and the formula (16) was obtained by substituting the above equation (17) OPGW1 can be calculated the melt volume V _m of the strand, it is possible to calculate the melting characteristics of the OPGW for arc current I _DC by using this result.

Description will now be made molten volume V _m should be noted when calculating the amount of melting of as described above OPGW1.

In the calculation of the melt amount in the melt amount calculation unit 22C, for the sake of simplicity, the actual structure of OPGW1 is replaced with a structure equivalent to this, and the melt volume V _m is considered with this schematic structure. Specifically, first, the actual OPGW1 structure as shown in FIGS. 4A and 5A is constructed, and as shown in FIGS. The structure is simplified as OPGW 31 and 41 in which 12 segments are assembled to form a circular aluminum layer 31A and 41A and the outer peripheral surface in contact with the inner peripheral surface of the aluminum layers 31A and 41A. In such OPGWs 31 and 41, the heat transfer amount from the arc 11 is first injected into the aluminum layers 31A and 41A, and the circumferential portions of the OPGWs 31 and 41 are melted and removed, and then the lower iron layers 31B and 41B. The amount of heat transferred from the arc 11 is injected into the part. Here, the outer diameters D1 and D2 of the OPGWs 31 and 41 are equal to the outer diameters D1 and D2 of the OPGD1, and the cross-sectional areas of the aluminum layers 31A and 41A and the iron layers 31B and 41B are also shown in FIG. And it was set as the value equivalent to those of Fig.5 (a). Incidentally, in the example shown in FIGS. 4A and 5A, D1 = 11.5 mm, D2 = 16 mm, d1 = 3 mm, and d2 = 1.85 mm.

The melt volume V _m is considered in the OPGWs 31 and 41. Specifically, after a portion having a volume obtained by multiplying the thickness of the aluminum layer 31A or 41A or the iron layer 31B or 41B of the OPGW 31 or 41 by the contact area of the arc 11 is melted, the arc 11 is formed in another area. It is thought to move and melt the area. If the arc current I _DC and the arc heat transfer is sufficiently large from the time a large arc 11 to OPGW31 is the fact that all the wires in the circumferential direction of the OPGW31 melts, in this embodiment, easily touches the arc 11 The melting amount R _m of the upper half (for example, 3 out of 6 wires in the case of FIG. 4 and 6 out of 12 wires in the case of FIG. 5) was calculated. Here, somewhere in wires of the outermost layer of half the axial OPGW of OPGW31 was defined as 100% melt volume _{R m} in the case of the total amount the melt.

For example, as shown in FIG. 6 (a), or when the arc current I _DC is small, when the outer diameter D1, D2 of OPGW31,41 is thick, the diameter Φ1 of the arc 11 than half the circumferential length of OPGW31,41 May be shorter. In such a case, a portion having a shape as shown in FIG. 6A is melted, and after it has melted, the arc 11 moves in the circumferential direction of the OPGWs 31 and 41. Such a shape melts. Thus, the molten amount _{R m} when the length in the circumferential direction of the OPGW31,41 molten part reaches a half circumferential length .phi.2 (see FIG. 6 (b)) of OPGW31,41 is 100%.

On the other hand, or when the arc current I _DC is large, when the outside diameter of the OPGW31,41 is thin, the arc diameter may become longer than the half circumference Φ2 of OPGW31,41. At this time, as shown in FIG. 6B, when the arc area is smaller than the area of the exposed portion 12 of the OPGWs 31 and 41, the portion having the shape as shown in FIG. 6B is melted.

  Furthermore, as shown in FIG. 6C, when the arc area is larger than the area of the exposed portion 12 of the OPGWs 31 and 41, the portion having the shape as shown in FIG. 6C is melted.

Melting amount R _m of 100% when shaped portion, such as shown in FIG. 6 (b) or FIG. 6 (c) is the total amount the melt.

Melt quantity calculating unit 22C in this embodiment, the predetermined melt volume R _m by performing such the above operations _(e.g., 40%, 70%, 100%) determining the time relationship to the arc current I _DC to the .

Here, in this embodiment, the arc current I _DC is changed from 1 to 100 kA with reference to the lightning observation examples so far, and the gap length L _gap is changed from 50 mm to 1500 mm with reference to the conventional DC arc test conditions of OPGW1. I let you. Specifically, the parameter relating to the gap length L _gap set in the parameter setting unit 21 was changed.

The display unit 23 displays melting characteristics and the like obtained as a result of predetermined calculation processing by the calculation processing unit 22. Melt properties, for example take the arc current I _DC to the horizontal axis, the vertical axis represents the time until a predetermined melt volume is displayed as a plot illustrating the relationship between them.

FIG. 7 and FIG. 8 show the arc current _IDC -time t characteristics (display example on the display unit 23) based on the calculation result by the simulator according to the present embodiment. FIG. 7 is a characteristic diagram when OPGW31 is 80 mm ² (in the case shown in FIG. 4A), and FIG. 8 is a characteristic diagram when OPGW31 is 140 mm ² (in the case shown in FIG. 5A). These are the calculation results indicating the dependency of the melting amount of OPGW31,41 _{R m} 40%, the arc current I _DC of the melting time t in the case of 70% and 100%. For comparison, in FIG. 7 and FIG. 8, the relationship between current and time when the passing electric quantity Q is 100 C, 500 C, and 1000 C is indicated by a broken line.

  7 and 8, (a) shows the results when OPGW 31 is the cathode and (b) is the anode.

The plots in FIG. 7 and FIG. 8 are obtained by performing a DC arc test with the test apparatus shown in FIG. 1 and disconnecting 3 wires out of 6 when OPGW1 is 80 mm ² and 6 wires out of 12 when 140 mm ² . Test data. In these tests, in order to suppress the movement of the arc in the longitudinal direction on the OPGW 1, the vinyl tapes 9 and 10 are wound around the surface of the OPGW 1 to expose only the vicinity of the arc occurrence location. That is, the exposed portion 12 is formed.

The length L _ex of the exposed portion in the present calculation was equivalent to that in each test (Figure 7: 40 mm, Figure 8: 20 mm).

Referring to FIGS. 7 and 8, the following can be understood. First, in the past, the melting characteristics were evaluated by the passing electricity quantity of GW or OPGWP. However, based on this idea, for example, the plot of FIG. 7A should be aligned in parallel with the broken electricity amount constant passage line. It is. However, it is not so, rather, it is in good agreement with the trend of this solid calculation result. Further, in either case of FIG. 7 or FIG. 8, the time required for melting is shorter when OPGW is the cathode than when OPGW is the anode. This is due to, for example, the polarity effect of the _total heat transfer amount Ptotal.

Further, paying attention to the melting amount R _m of test data obtained from the calculation results and plotted by simulator, in any case, it is more in the case of during anodic than that in the OPGW1 a cathode shows a lower value. In other words, towards the case at the anode OPGW is compared during cathode, it is disconnected at a lower melt volume R _m. This is considered to be because the arc is less likely to move at the anode than at the cathode, regardless of whether the material is aluminum or iron. Comparison with the above test results confirmed the validity of the calculation results by the simulator according to this embodiment.

  INDUSTRIAL APPLICABILITY The present invention can be effectively used in an industrial field that handles overhead ground wires that may be blown by lightning.

1 OPGW
2 Counter electrode 11 Arc 12 Exposed portion 21 Parameter setting unit 21A Arc condition setting unit 21B OPGW condition setting unit 22 Arithmetic processing unit 22A Heat transfer amount calculation unit 22B Heat transfer area calculation unit 22C Melting amount calculation unit

Claims (7)

DC arc test for an overhead ground wire that simulates a lightning strike by simulating a lightning strike by supplying an arc current from a DC arc to an overhead ground wire that is fixed at both ends with a predetermined tension applied The simulation method of
The total amount of heat transferred to the overhead ground wire by the direct current arc, the arc current of the direct current arc supplied to the overhead ground wire, the arc conditions including the supply time of the arc current, the size of the overhead ground wire and the strand A simulation method of a DC arc test for an overhead ground wire, which is calculated by the sum of the heat transfer amount by electron transport and the heat transfer amount by convective heat transfer based on the overhead ground wire condition including the material of the ground. In the simulation method of the direct-current arc test according to claim 1,
Calculating the relationship between the time until the aerial ground wire is melted by a predetermined amount and the arc current based on the total heat transfer amount to obtain the melting characteristics of the aerial ground wire represented by the relationship between the time and the arc current. DC arc test simulation method for characteristic overhead ground wire. In the simulation method of the direct-current arc test with respect to the overhead ground wire of Claim 1 or Claim 2,
The amount of heat transfer by the convective heat transfer is based on an arc jet ejected from the counter electrode opposed to the overhead ground wire through a gap toward the overhead ground wire, and has a predetermined heat transfer coefficient, While obtaining by the product of the heat transfer area which is the area of the area where the DC arc is in contact with the outer peripheral surface of the overhead ground wire and the temperature difference between the DC arc and the surface of the overhead ground wire,
The method of simulating a DC arc test for an overhead ground wire, wherein the heat transfer area is changed according to an arc current of the DC arc and a material of the overhead ground wire. A DC arc test simulator for an overhead ground wire for simulating a direct current arc test simulating a lightning strike by bringing a DC arc into contact with an overhead ground wire fixed at both ends with a predetermined tension applied. ,
Parameter setting to set the arc current including the arc current of the DC arc supplied to the sample ground wire, the arc current supply time, and the size of the overhead wire and the material of the wire And
Based on the parameters set in the parameter setting unit, the amount of heat transferred by electron transport and the amount of heat transferred by convective heat transfer are calculated, and both are added to calculate the total amount of heat transferred to the overhead ground wire by the DC arc. And a DC arc test simulator for an overhead ground wire. In the simulator of the direct-current arc test for the overhead ground wire according to claim 4,
The calculation unit calculates a relationship between the arc current and a time until the overhead ground wire is melted by a predetermined amount based on the total heat transfer amount, and melts the overhead ground wire represented by the relationship between the time and the arc current. DC arc test simulator for aerial ground wire, characterized in that it requires characteristics. In the simulator of the direct-current arc test for the overhead ground wire according to claim 4 or claim 5,
The calculation unit is based on an arc jet ejected from the counter electrode toward the aerial ground wire, and the heat transfer amount due to the convective heat transfer is determined at a predetermined heat transfer coefficient, the outer peripheral surface of the aerial ground wire. While calculating by the product of the heat transfer area which is the area of the area where the DC arc is in contact and the temperature difference between the DC arc and the surface of the overhead ground wire,
The simulator of a direct current arc test for an overhead ground wire, wherein the heat transfer area is calculated as a function of the arc current and the material of the overhead ground wire. DC arc test for an overhead ground wire that simulates a lightning strike by simulating a lightning strike by supplying an arc current from a DC arc to an overhead ground wire that is fixed at both ends with a predetermined tension applied Simulation software,
Heat transfer amount and convective heat transfer by electron transport based on the arc conditions including the set direct current arc current, the arc current supply time, and the overhead ground wire conditions including the size of the overhead ground wire and the type of wire. A step of calculating the amount of heat transfer due to,
A step of calculating a total amount of heat transfer to the overhead ground wire by the DC arc by adding the amount of heat transfer by electron transport and the heat transfer amount by convective heat transfer; Arc test simulation software.