JP3132378B2 - Estimation method of electric line temperature - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for estimating the temperature of an electric wire which is particularly suitable for monitoring the temperature of an electric wire having a stranded structure such as an overhead electric power transmission line.

[0002]

2. Description of the Related Art Conventionally, since the temperature (wire temperature) of various electric lines such as an overhead transmission line having a stranded structure cannot be directly measured, generally a power current transformer (CT) installed in the transmission line is generally used. ) Is detected indirectly by detecting the energizing current based on the secondary output.

When the supplied current reaches a predetermined threshold value, a current relay is activated to stop the power transmission from being overheated due to an excessive transmission current, and the power transmission is stopped by an open trip of a circuit breaker or the like. Are equal.

However, as described above, it is not possible to detect the actual temperature of the electric line only by detecting the current flowing through the electric line, and it is not possible to monitor the actual thermal operation state. There are inconveniences.

Therefore, the applicant of the present application filed Japanese Patent Application No.
We have already invented a method for monitoring the temperature of an electrical line described in the specification and the drawings of the application No. 7090.

In the temperature monitoring method of this patent application, an estimated value of the wire internal temperature based on the amount of heat generated inside the wire of the monitoring line is calculated from the detected value of the current flowing through the monitoring line, and the wire temperature based on the flowing current is calculated. presume.

Further, an estimated value of the electric wire surface temperature based on the amount of heat generated on the electric wire surface of the monitoring line is calculated from the detected values of each weather condition such as temperature and solar radiation intensity to estimate the electric wire temperature based on each weather condition. .

Further, a temperature difference between the inside of the electric wire of the monitoring line and the surface of the electric wire is obtained from a difference between the estimated value of the internal temperature of the electric wire and the estimated value of the surface temperature of the electric wire. The temperature difference of the monitoring line is obtained by summing the estimated values of the electric wire temperatures.

In this case, the current flowing through the monitoring line, the temperature,
Based on weather conditions such as insolation, the electric wire temperature of the monitoring line is estimated by calculation, and the electric wire temperature itself is detected.

Since the temperature of the monitoring line is estimated by correcting the weather conditions, the occurrence of abnormal overheating due to the overcurrent is monitored with high accuracy in consideration of the actual weather conditions.

By the way, the calculation for estimating the electric wire temperature based on the supplied current is performed by the following exponential function <1>.

[0012]

[Number 1] θin = {Δθimax (In / Imax ) k -θi n-1} · [1-exp {- (t n -t n-1) / Ti}] + θi n-1 = (Δθi-θi n ₋₁ ) · {1-exp (−Δt / Ti)} + θi _n−1 ... <1> In the expression, t _n , t _n−1 ,.

T _n , t _n-1 : n-th (current), _n-1- th (previous) operation time [minutes] Δt: time interval of operation (sampling / control) (= t _{n
-T n-1) θi n,} θi n-1: the time t _n, t _n-1 of the estimated temperature (temperature estimated value) [℃] In: Detection value of the current sensor at time t _n (measured line current value)
[A] Imax: Reference value of energizing current (nominal allowable current value) [A] Δθimax: Saturation temperature rise value at Imax [° C] Ti: Temperature change time constant due to energizing current change k: Internally generated caloric saturation value due to current ratio Correction index The exponent k of (In / Imax) in the equation is an internally generated calorific value saturation correction index, which is about 2 in the case of an electric line.

In the above-mentioned application, Δθmax, θi
Although the wire temperature is determined using n as the heat quantity, the equation for calculating the heat quantity is substantially the same as the exponential function equation <1> because the temperature and the heat quantity are in a proportional relationship.

Further, the calculation for estimating the electric wire temperature based on the above-mentioned weather conditions such as the temperature and solar radiation intensity can also be performed by an exponential function similar to the exponential function <1>.

In the above-mentioned application, the temperature of the monitoring line is estimated by adding the temperature difference between the internal temperature of the electric wire based on the supplied current and the surface temperature of the electric wire based on weather conditions to a set temperature corresponding to the air temperature. Estimated temperature based on weather conditions, estimated temperature θan based on air temperature, estimated temperature θ based on insolation intensity
When sn is used, a similar result can be obtained by estimating the temperature θn of the monitoring line from the following estimating equation <2> in which the estimated temperatures θin, θan, and θsn are added.

[0017]

[Equation 2] θn = θin + θan + θsn ... <2>

[0018]

In the conventional method for estimating the temperature of an electric line, the monitoring line is laid outdoors, and although the electric line temperature fluctuates greatly due to the heat dissipation by wind, Since this effect is not taken into account, there is a problem in that highly accurate estimation of the wire temperature cannot be actually performed.

For example, in an actual transmission line,
Its specific resistance increases and decreases according to the temperature of the wireway,
Due to this change, the amount of heat generated in the monitoring line based on the supplied current changes, and the temperature of the electric line changes depending on the temperature change of its specific resistance.

Therefore, in the case of the conventional method for estimating the temperature of an electric line, there is a problem that an estimation error of the electric line temperature occurs due to the temperature change of the specific resistance, and the temperature of the monitoring line cannot be accurately estimated.

An object of the present invention is to be able to estimate the temperature of a monitoring line in consideration of the influence of wind. Still another object of the present invention is to eliminate the estimation error based on the temperature change of the specific resistance of the monitoring line and to more accurately estimate the wire temperature.

[0022]

According to a first aspect of the present invention, there is provided a method for estimating a temperature of an electric line, which is based on a current flowing through an electric line to be monitored (hereinafter referred to as a monitoring line).
The estimated value of the electric wire temperature at each time, temperature, temperature of the electric lines of estimating the electric wire temperature at each time of the monitoring line by adding the estimated value of the electric wire temperature at each time based on the weather conditions, such as solar irradiance In the estimation method, each of the estimated values is
Multiplying the reciprocal of the wind speed by the correction function formula and estimating the above at each time
Subjected to correction of the influence of the wind on the value, the respective estimated values, and requests to correct the effects of the wind. Further, the electric wire path according to claim 2
In the case of the method for estimating the temperature of
The estimated value of the wire temperature is calculated from the following formula based on
_{Because, θin = (Δθin-θi n} -1) · {1-exp (-Δt / Tin)} + θi n-1 tn, t n-1: n -th (time), the calculation of _n-1 th (last) time Delta] t: calculation of the time interval _{(= t n -t n-1} ) Tin: energizing current change due to the temperature change time constant θin, θi _n-1: the time t _n, the estimated value of t _n-1 (estimated temperature) Derutashitain : a temperature rise value of the time _{t n, Δθin = Δθimax (in} / Imax) k in: current sensor at time t _n detection value Imax: the reference value of the energizing current Derutashitaimax: saturation in Imax temperature rise Ti: energizing current Temperature change time constant k due to change k: Index of correction of internally generated calorific value by current ratio Based on temperature and solar radiation intensity, each weather condition is calculated from the following formula.
An estimated value of the monitoring line based on the condition is obtained, and θan = (An−θan ₋₁ ) · {1-exp (−Δt / Ta)} + θan ₋₁ θsn = (Δθsmax · Sn−θsn ₋₁ ) · [1-exp {- ( t n -t n-1) / Ts}] + θs n-1 = (Δθs-θs n-1) · {1-exp (-Δt / Ts)} + θs n-1 θan , θa _n-1: time t _n, t _n-1 of the estimated value based on the temperature (estimated temperature) Ssn, Ss _n-1: time t _n, the estimated value based on the solar radiation of t _n-1 (estimated temperature) An : time t _n of measuring air temperature Sn: measurement irradiance at time t _n Derutashitasmax: irradiance saturation temperature rise value .DELTA..theta.s: time t _n of the temperature rise value Ta: change in temperature time constant due to temperature change Ts: temperature change due to the solar radiation intensity change The time constant is added to the estimated values θin, θan, θsn and the monitoring line is added.
Estimate the temperature θn (= θin + θan + θsn)
In the temperature estimation method, the estimated value θin
The following correction function formula f is added to the rising value Δθin and the temperature change time constant Tin.
_i1 (Wn) and f _i2 (Wn) are multiplied by
Subjected to _{correction, f i1 (Wn) = α} 1 / (Wn + β 1) + γ 1 f i2 (Wn) = α 2 / (Wn + β 2) + γ 2 Wn: wind speed α ₁ of the time _{t n, α 2, β 1} , β ₂ , γ ₁ , γ ₂ : constants For the above-mentioned estimated value θan, the following addition is made to the temperature change time constant Ta.
The effect of wind is corrected by multiplying the positive function expression fa (Wn).
_{And, fa (Wn) = α 3} / (Wn + β 3) + γ 3 Wn: time t _n of the wind speed _{α 3, β 3, γ 3} : per constant the estimated value Shitasn, the temperature rise value .DELTA..theta.s, temperature changes
The following correction function expressions f _s1 (Wn) and f _s2 (Wn) are added to the constant Ts.
Multiplied by the subjected to a correction of the influence of _{wind, f s1 (Wn) = α} 4 / (Wn + β 4) + γ 4 f s2 (Wn) = α 5 / (Wn + β 5) + γ 5 Wn: wind speed of time t _n α _{4, α 5, β 4,} β 5, γ 4, γ 5: constant each estimate θin, θan, the Shitasn, to correct the effects of the wind
Is what you want.

Therefore, the estimated value of the electric wire temperature based on the energizing current and each weather condition can be accurately obtained without the influence of the heat dissipation due to the wind, and the influence of the wind is eliminated by integrating these estimated values. Then, the temperature of the monitoring line is accurately estimated.

In the method for estimating a wire temperature according to a third aspect of the present invention, the temperature of the estimated value θin of the wire temperature based on the supplied current is calculated.
The rise value Δθin is calculated using the correction function f _i1 (Wn)
Correction of the effect of temperature change on the specific resistance of the next monitoring line
Corrected by multiplying the equation f (Rt), f (Rt ) = 1 + 1 / {Rt / (θi n-1 -20) +1} Rt: a resistivity, uniquely Rt ₀ at temperature t ₀ resistance
Assuming that Rt = Rt ₀ ｛1 + αt ₀ (t−t ₀ )｝ The temperature change time constant Tin of the estimated value θin is compensated for by the effect of wind.
Based on the positive function formula f _i2 (Wn) and the correction function formula (Rt)
Can, corrected by the following equation, Tin = {Ti / f ( Rt)} · f i2 (Wn) an estimate of the electric wire temperature based on passing Denden flow, wind effects and audit
It is obtained by correcting the influence of the temperature change of the specific resistance of the line of sight.

Therefore, the estimated value of the electric wire temperature based on the flowing current, which is affected by the temperature change of the specific resistance of the monitoring line, eliminates the influence of the wind and performs a correction according to the temperature change of the specific resistance. The temperature of the monitoring line is more accurately estimated.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS. Here, both the effect of wind and the effect of temperature change of the specific resistance of the monitoring line are corrected, and based on the corrected estimated values θin, θan, θsn,
The temperature of the monitoring line is estimated from the estimation operation formula <2> of Expression 2.

Then, for convenience of explanation, first, correction of the influence of temperature change of the specific resistance value of the monitoring line will be described.
When the monitoring line is a transmission line, the specific resistance Rt at the temperature t [° C.] is a constant mass resistance temperature coefficient α _t0 [° C. ⁻¹ ] of the temperature t ₀ [° C.] represented by the following equation (3). ], And is obtained by the arithmetic expression <4> of Expression 4.

[0028]

(Equation 3) In the equation, C is the conductivity [%] of the electric line, and t ₀ is the temperature [° C.] of the electric line.

[0029]

Rt = Rt ₀ {1 + α _t0 (t−t ₀ )}... <4>

Rt ₀ in the equation is a specific resistance at a temperature t ₀ [° C.]. As is apparent from the operation formula <3>, the constant mass resistance temperature coefficient α _t0 is determined by the monitoring line temperature t ₀ [° C.], and the specific resistance R is determined by the temperature coefficient α _t0 .
Since t depends, if the temperature t _{0 of the} monitoring line changes, the temperature coefficient α _t0 changes and the specific resistance Rt changes.

Further, the amount of heat generated based on the current flowing through the monitoring line changes due to the temperature change of the specific resistance Rt, and the temperature changes. Therefore, unless the temperature change of the specific resistance Rt is considered, the temperature of the monitoring line cannot be accurately estimated.

Therefore, a correction function f (Rt) for the temperature change of the specific resistance Rt is added to the exponential function equation <1>, and the fixed temperature rise value Δθi and the temperature change time constant of the exponential function equation <1> are obtained. From the following exponential function expression <5> in which Ti is changed to a temperature rise value Δθin and a temperature change time constant Tin of a function expression including a correction function expression f (Rt), an electric wire temperature based on the current is estimated, An estimated value (estimated temperature θin) of the electric wire temperature based on the supplied current is obtained by correcting the temperature change of the specific resistance Rt.

[0033]

Equation 5] _{θin = (Δθin-θi n-} 1) · {1-exp (- Δ
t / Tin)｝ + θi _n-1 <5> The temperature rise value Δθin and the temperature change time constant Tin in the equation <5> are calculated by the correction function f (R
Expressions <6a> and <6b> of the following Expression 6 using t) as a multiplier are shown.

[0034]

Equation 6 Δθin = (In / Imax) ² · Δθimax · f (Rt) · f _i1 (Wn) ··· <6a> Tin = {Ti / f (Rt)｝ · f _i2 (Wn) ··· <6b> , F _i1 (Wn) and f _{i2 of} the function formulas <6a> and <6b>
(Wn) is a wind speed correction function formula described later.

The correction function formula f (Rt) is calculated based on experiments and the like, and specifically, the specific resistance Rt and the previous value (time t
_n-1 ) based on the estimated temperature θi _n−1 , it is found that the following equation (7) is obtained.

[0036]

F (Rt) = 1 + 1 / {Rt / ( θin _- 1−20) +1} (7) Next, the correction of the electric wire temperature accompanying the heat dissipation by the wind will be described.

Firstly, heat dissipation by the wind prediction time, i.e. vary depending on wind Wn at time t _n, applied current and the estimated temperature θin based of each weather conditions, Shitaan, a relatively large impact on each Shitasn.

On the other hand, the estimated temperature θ based on the temperature and the solar radiation intensity
When the effect of heat dissipation due to wind is ignored, the arithmetic expressions of an and θsn are the following Expressions 8 and 9 similar to the exponential function expression <1>.
Are represented by exponential function expressions <8> and <9>.

[0039]

[Equation 8] θan = (An−θan ₋₁ ) · {1-exp (−Δt / Ta)} + θan ₋₁ ... <8>

Equation 9] θsn = (Δθsmax · Sn-θs n-1) · [1-exp {- (t n -t n-1) / Ts}] + θs n-1 = (Δθs-θs n-1) · {1-exp (-Δt / Ts )} + θs n-1 ... <9> both exponential <8>, θa _n-1 in _{<9>, θs n-1} , ... are the values of Hatsugi.

[0040] θan, θa _n-1: time t _n, the estimated temperature [℃] based on the temperature of _{t n-1 Ssn, Ss n} -1: time t _n, the estimated temperature based on the solar radiation of t _n-1 [℃ by solar radiation intensity variation:] An: time t measured temperatures _n [℃] Sn: time t _n of measuring solar irradiance [KW / m ^2] Δθsmax: irradiance saturation temperature rise value Ta: change in temperature time constant due to temperature changes Ts Temperature change time constant

Then, in each of the exponential function expressions <1>, <8>, <9> of Expressions 1, 8, and 9, the temperature rise values Δθi,
The value of the time t _n of Δθs Δθin, Δθsn and the time constant Ti, T
The values of a, the time t _n of Ts Tin, Tan, Tsn is to have a solid characteristic of approximately 6 both with respect to wind speed Wn at the same time t _n [m / s] has been found by experiment or the like.

Therefore, the temperature rise value Δ of the exponential function formulas <1>, <8>, <9> for obtaining the estimated temperatures θin, θan, θsn
.theta.i, .DELTA..theta.s, and temperature change time constants Tin , Ta, and Ts are each multiplied by a correction function for the influence of the wind to correct and eliminate the influence of the wind.

That is, the estimated temperature θin based on the supplied current
The temperature rise value Δθin exponential formula <5>, the temperature change time constant Tin, the temperature rise value of the exponential equation <1> delta
θi and the temperature change time constant Ti are multiplied by the correction functions f _i1 (Wn) and f _i2 (Wn) of the wind speed Wn in the equations <6a> and <6b>, and are obtained from the exponential function equation <5>.

The estimated temperature θan based on the air temperature is calculated by adding the wind speed Wn to the temperature change time constant Ta of the exponential function equation <8>.
From the following exponential function expression <10> multiplied by the correction function expression fa (Wn).

[0045]

## EQU10 ## θan = (An−θa)_n-1) · [1−exp {−Δt / (Ta · fa (Wn))}] + θa _n-1 = (An-θa_n-1) · {1-exp (−Δt / Tn)} + θa_n-1 … <10>

[0046] Further, for the estimated temperature θsn based on solar irradiance, temperature rise value of the exponential function expression <9> .DELTA..theta.s, correction function expression f _s1 (W wind speed Wn to temperature change time constant Ts
n) and f _s2 (Wn) are multiplied by an exponential function equation <11> of the following Expression 11.

[0047]

Equation 11] _{θsn = Δθs · f s1 (Wn} ) · [1-exp {-Δt / (Ts · f s2 (Wn))}] + θs n-1 ... <11>

Then, each correction function expression f _i1 (Wn) to f _s2
(Wn) is based on experiments and the like, and the following equations (12a), <12b>,.
2e>.

[0049]

F _i1 (Wn) = α ₁ / (Wn + β ₁ ) + γ ₁ ... <12a> f _i2 (Wn) = α ₂ / (Wn + β ₂ ) + γ ₂ ... <12b> fa (Wn) = α ₃ / _{(Wn + β 3) + γ} 3 ... <12c> f s1 (Wn) = α 4 / (Wn + β 4) + γ 4 ... <12d> f s2 (Wn) = α 5 / (Wn + β 5) + γ 5 ... <12e> each formula Α _{1 to} α ₅ , β _{1 to} β ₅ , and γ _{1 to} γ ₅ are constants, which vary depending on the type of electric wire, and are set to appropriate values obtained by experiments and the like.

Then, exponential function expressions <5>, <10>,
The estimated values (estimated temperatures θin, θan, θsn) of the electric wire temperature based on the supplied current, the air temperature, and the solar radiation intensity are obtained by <11>, and they are added by the estimation operation formula <2> and integrated to obtain 610.
temperature θn of mm ² of copper heart aluminum than line ACSR of monitoring line
As a result, under the conditions in which the supplied current, insolation intensity, wind speed, and air temperature change as shown by the solid lines c, d, e, and f in FIGS. 2, 3, 4, and 5, FIG. The result shown in FIG.

In the figure, the bold line a indicates the temperature of the monitoring line estimated by correcting the influence of the wind and the temperature change of the specific resistance of the monitoring line, and the thin line B indicates the measured temperature. As apparent from FIG. 1, the temperature of the monitoring line can be estimated with extremely high accuracy by taking into account the influence of the wind and the effect of the temperature change of the specific resistance of the monitoring line.

Further, each estimated θi is calculated by the
Instead of adding n, θan, and θsn, it is a matter of course that the temperature of the monitoring line may be estimated by obtaining and integrating the internal temperature and the surface temperature of the electric wire as in the above-mentioned application.

[0053]

The present invention has the following effects. First, since the estimated value of each electric wire temperature based on the energized current and each weather condition was obtained by correcting the effect of wind, the effect of heat dissipation due to wind was eliminated and the electric wire temperature of the monitoring line was accurately obtained and estimated. It is possible to accurately monitor the thermal operation state of the monitoring line and perform maintenance and control when abnormal overheating occurs.

Further, when the estimated value of the wire temperature based on the flowing current is obtained by correcting not only the effect of the wind but also the effect of the temperature change of the specific resistance of the monitoring line, the wire temperature based on the flowing current can be obtained with higher accuracy. Thus, it is possible to more accurately obtain and estimate the electric wire temperature of the monitoring line.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram for comparing an estimated value and an actually measured value of an electric wire temperature of a monitoring line according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a change in a current flowing through a monitoring line in FIG. 1;

FIG. 3 is an explanatory diagram of a change in the solar radiation intensity of the monitoring line in FIG. 1;

FIG. 4 is an explanatory diagram of a change in wind speed of a monitoring line in FIG. 1;

FIG. 5 is an explanatory diagram of a change in temperature of the monitoring line in FIG. 1;

FIG. 6 is a characteristic diagram of a change in wind speed of a calculation parameter of the estimated value in FIG. 1;

[Explanation of symbols]

 B. Estimated value of monitoring line temperature b. Actual measured value of monitoring line temperature

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) H02H 6/00 H02H 5/04

Claims (3)

(57) [Claims] An estimated value of an electric wire temperature at each time based on a current flowing through an electric line to be monitored (hereinafter referred to as a monitored line) ;
Temperature, the temperature estimation method of the electric lines of estimating the time of the electric wire temperature <br/> degree of the monitored line by adding the estimated value of the electric wire temperature at each time based on the weather conditions, such as solar irradiance, the Correction function of reciprocal of wind speed at each time for each estimated value
Multiply the equation to correct the effect of wind on the estimated values at each time.
Subjected, each of said estimated values, the temperature estimation method of the electric wire path, characterized in that obtained by correcting the influence of the wind. (2)Based on the current flowing through the monitoring line to be monitored
Then, an estimated value of the wire temperature is calculated from the following equation (1).
, (Equation 1)θin = (Δθin−θi _n-1 ) · {1-exp (-Δt / Tin)} + θi _n-1  tn, t _n-1 : The nth time (this time), _n-1 Second (previous) calculation time Δt: calculation time interval (= t _n -T _n-1 ) Tin: Temperature change time constant due to change in energizing current θin, θi _n-1 : Time t _n , T _n-1 Estimated value (estimated temperature) Δθin: time t _n Δin = Δθimax (In / Imax) ^k  In: time t _n Current sensor detection value Imax: Reference value of the conducting current Δθimax: Saturation temperature rise value at Imax Ti: Time constant of temperature change due to change in conduction current k: Correction index for internally generated calorific value saturation value based on current ratio Based on the temperature and solar irradiance, each of
Obtain an estimated value of the monitoring line based on weather conditions, (Equation 2)θan = (An−θa _n-1 ) · {1-exp (−Δt / Ta)} + θa _n-1  θsn = (Δθsmax · Sn−θs _n-1 ) · [1-exp ｛− (t _n -T _n-1 ) / Ts｝ ] + Θs _n-1 = (Δθs−θs _n-1 ) · {1-exp (-Δt / Ts)} + θs _n-1  θan, θa _n-1 : Time t _n , T _n-1 Estimated value based on temperature (estimated temperature) Ssn, Ss _n-1 : Time t _n , T _n-1 Value based on solar radiation (estimated temperature) An: time t _n Measured air temperature Sn: time t _n Measured solar radiation intensity Δθsmax: Insolation intensity saturation temperature rise Δθs: time t _n Temperature rise Ta: Temperature change time constant due to temperature change Ts: Time constant of temperature change due to change of solar radiation intensity The estimated values θin, θan, θsn are added and the monitoring line
Estimate the temperature θn (= θin + θan + θsn)
In the temperature estimation method, For the estimated value θin, the temperature rise value Δθin, when the temperature changes
The correction function f of the following equation 3 is added to the constant Tin. _i1 (Wn), f _i2
(Wn) Multiply each to correct for wind effects, (Equation 3)f _i1 (Wn) = α ₁ / (Wn + β ₁ ) + Γ ₁  f_i2(Wn) = α_Two/ (Wn + β_Two ) + Γ_Two Wn: time t _n Wind speed α ₁ , Α _Two , Β ₁ , Β _Two , Γ ₁ , Γ _Two :constant For the estimated value θan, the temperature change time constant Ta
Correction of wind effect by multiplying by the correction function formula fa (Wn)
Subject to (Equation 4)fa (Wn) = α _Three / (Wn + β _Three ) + Γ _Three Wn: time t _n Wind speed α _Three , Β _Three , Γ _Three :constant For the estimated value θsn, the temperature rise value Δθs,
The correction function f of the following equation 5 is added to the constant Ts. _s1 (Wn), f
_s2 (Wn) to correct for wind effects, (Equation 5)f _s1 (Wn) = α _Four / (Wn + β _Four ) + Γ _Four f _s2 (Wn) = α _Five / (Wn + β _Five ) + Γ _Five Wn: time t _n Wind speed α _Four , Α _Five , Β _Four , Β _Five , Γ _Four , Γ _Five :constant The above estimated values θin, θan, θsn are corrected for the effect of wind.
A method for estimating the temperature of an electric line, which is characterized by being obtained. 3. An estimated value θin of an electric wire temperature based on a flowing current.
Of the temperature rise value Δθin is corrected by the correction function f _i1 (W
n) and the following equation 6
Effect of the correction function expression f a (Rt) corrected by multiplying, [6] f (Rt) = 1 + 1 / {Rt / (θi n-1 -20) +1} Rt: a resistivity, the Rt ₀ Inherent resistance at temperature t ₀
Assuming that Rt = Rt ₀ ｛1 + αt ₀ (t−t ₀ )｝ The temperature change time constant Tin of the estimated value θin is compensated for by the effect of wind.
Based on the positive function formula f _i2 (Wn) and the correction function formula (Rt)
Then, correction is made by the following equation (7). Tin = {Ti / f (Rt)}. _Fi2 (Wn) The estimated value of the wire temperature based on the current is calculated by the influence of wind.
Of the specific resistance of the monitoring and monitoring lines by compensating for the effects of temperature changes.
3. The method according to claim 2, wherein the temperature of the electric line is estimated.
Law.