JP3129181B2 - How to determine load limit of electric line - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a load limit judging method for an electric line, in particular, for judging the necessity of load limit based on a thermal limit of a stranded wire line such as an overhead transmission line.

[0002]

2. Description of the Related Art Conventionally, in this type of electric line, since it is impossible to directly detect the electric temperature of the electric line and directly grasp the thermal limit thereof, the electric current flowing through the electric line is generally detected.
The necessity of load limitation is determined based on the magnitude of the supplied current, and, based on the result of this determination, for example, power supply to each load feeder of the transmission line is selectively cut off to perform load limitation.

[0003] In this case, the electric wire temperature is determined by the energizing current and the air temperature,
It varies depending on weather conditions such as solar radiation. For example, even if the current is the same, the amount of current that can be transmitted (the amount of current flowing) differs between summer and winter, so it is necessary to limit the load based on a constant current value. If the reference current value is set assuming a harsh summer season, the load limit acts in winter before the current reaches the limit, and effective use of the power line can be achieved. There are no inconveniences.

On the other hand, the applicant of the present application filed Japanese Patent Application No. Hei.
As described in the specification and drawings attached to the application for application No. 09, a method for monitoring the temperature of a wire which has already been invented by estimating the wire temperature of this kind of wire in consideration of the flowing current and weather conditions has already been invented.
Filed.

In the temperature monitoring method of the present application, an estimated value of the temperature inside the electric wire of the monitoring line is calculated and calculated from the current flowing through the electric line (hereinafter referred to as a monitoring line) to be monitored, and the ambient temperature and the solar radiation intensity are calculated. The estimated value of the wire surface temperature of the monitoring line is calculated and obtained from the weather conditions of the monitoring line, the temperature difference between the inside of the wire of the monitoring line and the wire surface is calculated from the difference between the two estimated values, and the temperature of the wire surface temperature of the monitoring line is calculated as the temperature. The temperature of the monitoring line is obtained by adding the temperature difference.

In this case, when abnormal overheating due to an overcurrent occurs, the amount of heat generated inside the wire becomes larger than the amount of heat generated on the wire surface, and the wire temperature is calculated from the temperature obtained by adding the temperature difference to the set value of the wire surface temperature. It can be estimated and estimated without actual measurement.

Since the temperature of the electric wire is estimated in consideration of the current flowing through the electric line and the weather conditions, the temperature of the monitoring line is monitored in consideration of the weather conditions.

[0008]

In the above-described conventional method for determining the load limit of an electric wire, even if the temperature of the electric wire is estimated in consideration of the weather conditions by the temperature monitoring method of the above-mentioned application, the current value of the electric wire is not considered. Since only the temperature of the wire is estimated, it is not determined that the load limit is necessary unless the wire temperature becomes equal to or higher than the temperature at which the load limit is actually required, and the same is true for the reverse determination. As a result, there is a problem that the excess or deficiency of the load limit is frequently repeated, which causes a so-called control hunting phenomenon.

Furthermore, it is not easy to set a reference level for the judgment. If this level is set low, the load can be surely limited. There are also problems that cannot be done.

According to the present invention, the necessity of load limiting is determined without delay so that the current flowing through the electric line can be controlled to a maximum current allowable from a thermal limit in consideration of weather conditions. That is the task.

[0011]

In order to solve the above-mentioned problems, the present invention provides a method for determining the load limit of an electric line, which comprises:
In the case of claim 1, the judgment level of the load limit of the electric line is set to a dangerous temperature higher than the maximum allowable temperature of the electric line, and the temperature rise at the amount of heat generated based on the current carrying current of the electric line.
Amount based on the energizing current obtained in the previous estimation calculation.
Add to the constant temperature, based on the current carrying current of the electric line
Periodically estimating the temperature at present and after the fixed time
Repeatedly, the current weather condition of
The temperature rise in the amount of heat generated based on temperature and solar radiation intensity
In addition to the estimated temperature based on the weather conditions obtained in the previous estimation calculation,
Current and previous based on the current weather conditions of the line.
The temperature estimation after a certain period of time is repeated periodically.
And the current and the current based on the current carrying current of the electric line.
Estimated temperature after a certain time and current weather conditions of the electric line
And the estimated temperature after the predetermined time based on
Predicting the temperature after the one <br/> constant over time to estimate the current temperature of the electric line from the current energizing current and weather conditions of the periodically the electric line Te, and predicted temperature after the predetermined time When the estimated temperature of the electric line is equal to or higher than the judgment level continuously for a predetermined time or more when the estimated temperature is equal to or higher than the judgment level continuously for a plurality of times, it is necessary to limit the load on the electric line. determination to this for outputting a feeder interruption command
It is characterized by the following . In the case of claim 2,
The judgment level of the line load limit is set to the maximum allowable temperature of the electric line.
Set higher than the degree critical temperature, the current energizing the electric line
The current temperature of the line based on the current is calculated by the following equation.
Estimated from, θin = {Δθimax (In / Imax) k -θi n-1} · [1-e
xp ｛− (t _n −t _n−1 ) / Ti｝] + θ i _n−1 = (Δθ i−
θi _n-1 ) · {1-exp (−Δt / Ti)} + θi _n-1 t _n , t _n-1 : The n-th (current) and _n-1- th (previous) calculations
Time Delta] t: calculation of the time interval _{(= t n -t n-1} ) θi n, θi n-1: the time t _n, t _n-1 of the estimated temperature In: Detection value of the energization current at time t _n Imax: energizing Current reference value (nominal allowable current value) Δθimax: Saturation temperature rise value at Imax Ti: Temperature change time constant k: Current conversion index The above-mentioned electric wire path based on temperature and solar radiation intensity as weather conditions
The current temperature, estimated from the calculation of the following two _{equations, 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:} the time t _n, the estimated temperature θsn based on temperatures _{t n-1, θs n-} 1: the time t _n, t _n-1 of the estimated temperature An based on solar radiation: at time point t _n Measured temperature Sn: measured solar irradiance Δθsmax at time t _n : solar irradiance saturation temperature rise value Ta: temperature change time constant due to temperature change Ts: temperature change time constant due to change in solar intensity Add the above estimated values θin, θan, θsn. Of the electric line
To estimate the current temperature θn (= θin + θan + θsn)
Expressions monitor number to several _{3 tn = T n + J1,} t n-1 = t n-1 + J1
As the temperature θn _{+ J1} (= θi ( _{n + J1} ) +
Periodically predicting θa ( _{n + J1} ) + θs ( _{n + J1} ))
Repeatedly, the predicted temperature θ _{n + J1} continuously rises a plurality of times.
Or the estimated temperature θ
n continuously exceeds the judgment level for a predetermined time or more
Sometimes, it is determined that there is a need to
Output a leader shutoff command.
You.

Therefore, in the case of claims 1 and 2, the electric wire
Electric wire temperature estimated from the generated heat based on the current flowing through the circuit
And electric wires estimated from the amount of heat generated based on temperature and solar radiation intensity
Add the temperature and take into account the current flowing through the line and the weather conditions
And to estimate the current and temperature after a predetermined time, predicted temperature after a certain time estimated indicates a continuous rise, when it is determined that reliably reach a critical temperature in this state, or,
Conductive when the estimated temperature is determined to have become a critical temperature higher than a certain time of the line, is determined is output feeder shutoff is that it is necessary to delay rather load limiting so-called predictive determination method wires The current flowing through the road is limited without excess or deficiency.

In order to further improve the determination accuracy ,
In the case of claim 3, the first-stage determination level of the load limitation of the electric line
Was set to a short time use maximum allowable temperature of the electric line, the
Short-term use of the second-stage judgment level of the load limit of the electric line
Set a dangerous temperature higher than the maximum allowable temperature , and
Calculate the amount of temperature rise with the generated heat based on the current carrying current
To the estimated temperature based on the current
Add the current and the current based on the current carrying current of the power line
Estimating the temperature after the predetermined time is periodically repeated.
Then, the temperature of as the current weather conditions of the electric line, solar radiation Strong
The previous estimation based on the temperature rise in the heat generated based on the temperature
Add to the estimated temperature based on the weather conditions obtained by the calculation, and
Current and the certain time based on the current weather condition of the electric line
The temperature is periodically repeated to estimate the temperature after the electric wire
Current based on the current carrying current of the road and after the certain time
Estimated temperature and current based on current weather conditions of the electrical line
And the estimated temperature after the predetermined time and periodically
From the current carrying current and weather conditions of the cableway,
The current temperature of the road is estimated and the temperature after the predetermined time
Degree, and the predicted temperature after the certain time is continuously increased several times.
When the level is rising and becomes equal to or higher than the second-stage judgment level,
The estimated temperature of the electric line is continuously greater than or equal to a first predetermined time.
When the level exceeds the second-stage judgment level or when the
The second temperature is equal to or longer than the second predetermined time when the constant temperature is longer than the first predetermined time.
When the level continuously exceeds the first-stage determination level,
Judging that it is necessary to limit the load on the electric line,
A disconnection command is output. Also,
In the case of claim 4, the first-stage determination level of the load limit of the electric line is set.
To the maximum allowable short-time temperature of the cable
Use the second-stage judgment level of the load
Set use maximum allowable temperature higher than critical temperature, the electric line
The current temperature of the line based on the current
Estimated from the calculation of the equation of the technique, θin = {Δθimax (In / Imax) k -θi n-1} · [1-e
xp ｛− (t _n −t _n−1 ) / Ti｝] + θ i _n−1 = (Δθ i−
θi _n-1 ) · {1-exp (−Δt / Ti)} + θi _n-1 t _n , t _n-1 : The n-th (current) and _n-1- th (previous) calculations
Time Delta] t: calculation of the time interval _{(= t n -t n-1} ) θi n, θi n-1: the time t _n, t _n-1 of the estimated temperature In: Detection value of the energization current at time t _n Imax: energizing Current reference value (nominal allowable current value) Δθimax: Saturation temperature rise value at Imax Ti: Temperature change time constant k: Current conversion index The above-mentioned electric wire path based on temperature and solar radiation intensity as weather conditions
The current temperature, estimated from the calculation of the following two _{equations, 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:} the time t _n, the estimated temperature θsn based on temperatures _{t n-1, θs n-} 1: the time t _n, t _n-1 of the estimated temperature An based on solar radiation: at time point t _n Measured temperature Sn: measured solar irradiance Δθsmax at time t _n : solar irradiance saturation temperature rise value Ta: temperature change time constant due to temperature change Ts: temperature change time constant due to change in solar intensity Add the above estimated values θin, θan, θsn. Of the electric line
To estimate the current temperature θn (= θin + θan + θsn)
Expressions monitor number to several _{3 tn = T n + J1,} t n-1 = t n-1 + J1
As the temperature θn _{+ J1} (= θi ( _{n + J1} ) +
Periodically predicting θa ( _{n + J1} ) + θs ( _{n + J1} ))
Repeatedly, the predicted temperature θ _{n + J1} continuously rises a plurality of times.
The estimated temperature is higher than the second-stage determination level in the
Degree θn is continuously longer than the first predetermined time.
Wherein the or said estimated temperature θn time becomes above bell first
The second predetermined time longer than the predetermined time
The load on the electric line when the level exceeds the one-step judgment level
Outputs feeder shut-off command when it is determined that restriction is required
It is characterized by the following.

Therefore, in the case of the third and fourth aspects, the load
Judgment of the necessity of restriction is the highest allowed for short-time use of electric line
The first-stage judgment level set for the storage temperature and this level
2nd judgment level set to higher dangerous temperature of electric line
And two levels of judgment are provided.
In the same way as in
This is performed by estimating the temperature at present and after a certain time .

[0015] Then, the determination of the two-stage, when the prediction temperature after a certain time in consideration of the weather conditions continuously shows an upward trend, it is determined that this state the reach certainly dangerous temperature, the electric lines When it is determined that the estimated temperature is equal to or higher than the dangerous temperature for the first predetermined time or more, the estimated temperature of the electric line becomes the maximum allowable temperature for a short time or more for the second predetermined time or more. Even when the dangerous temperature may be reached, it is determined that there is a need to limit the load. A feeder cutoff command is output, and the current flowing through the power line is limited without excess or deficiency.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described.
This will be described with reference to FIGS. First, estimation and prediction of the temperature of an electric wire (electric wire temperature) in consideration of the energized current and weather conditions will be described.

The estimation and prediction of the wire temperature are performed by estimating the current wire temperature as described below, and further assuming that the current event (current, solar radiation, temperature, etc.) will continue until a predetermined time J1 has elapsed. Is what you do.

Estimation of Current Temperature In general, the amount of heat (generated heat) generated in an object per unit time dt is the sum of the amount of heat that raises the object temperature by the unit temperature dθ and the amount of heat released to the outside. The time change of the temperature is determined by using the amount of heat (generated heat) Q [KW], the heat capacity C [KW second / ° C.] and the heat dissipation coefficient H [KW / ° C.] of the object within a unit time as parameters. To θ
If [° C.] and the elapsed time are t [seconds], it is expressed by the following heat transfer equation <1> of Equation 1.

[0019]

Q · dt = C · dθ + H · θ · dt (1)

The heat transfer type <1> is given by Q / H = θma
Assuming that x, the general solution θ is represented by the following equation (2) of Expression 2.

[0021]

[Equation 2] θ = θmax · {1-exp (−t / T)}｝ <2>

As is evident from equation (2), the temperature θ of the object is determined by the time according to a function formula having the rising saturation temperature θmax (= Q / H) and the time constant T (= C / H) as constants. t
Changes exponentially with respect to.

The wire temperature of the wire structure of the stranded structure also changes with a constant time constant in accordance with the exponential function characteristic of the equation (2) due to the change in the calorific value. Can be estimated from a simple exponential temperature calculation.

In this case, if the change in the wire temperature based on the supplied current and the change in the wire temperature based on the weather conditions are individually predicted and added and synthesized, the current wire temperature can be estimated in consideration of the supplied current and the weather conditions. I can do it.

The electric wire temperature based on the supplied current is calculated based on the supplied current by calculating the following exponential function equation <3>.
It can be estimated from the amount of heat generated .

[0026]

Equation 3] 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 ... <3> In the equation, tn, tn ₋₁ ,. t _n , t _n-1 : n-th (current), _n-1- th (previous) calculation time [minutes] Δt: calculation (sampling / control) time interval (= t _{n
-T n-1) θi n,} θi n-1: the time t _n, t _n-1 of the estimated temperature [° C.] an In: Detection value of the current sensor at time t _n (measured line current value)
[A] Imax: Reference value of the 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: Current conversion index

The exponent k of (In / Imax) in the equation
Is a current conversion index, which is almost 2 in the case of an electric line.

Further, in the above-mentioned application, Δθmax, θ
Although the wire temperature is determined using in as the heat quantity, the equation for calculating the heat quantity is substantially the same as the exponential function equation <3> because the temperature and the heat quantity are in a proportional relationship.

Next, when the temperature and the solar radiation intensity are considered as weather conditions, the electric wire temperature θa based on the temperature and the solar radiation intensity is considered.
n and θsn are the following equations 4 and 5 similar to the exponential function equation <3>.
Temperature and solar radiation by the exponential function formulas <4> and <5>
It can be estimated from the heat generated based on the strength .

[0030]

Equation 4 θan = (An−θan ₋₁ ) · {1-exp (−Δt / Ta)} + θan ₋₁ ... <4>

[0031]

## EQU5 ## θsn = (Δθsmax · Sn−θsn ₋₁ ) · [1-exp
_{{- (t n -t n-} 1) / Ts}] + θs n-1 = (Δθs-θs
_n-1 ). {1-exp (-. DELTA.t / Ts)} +. theta.sn _-1 ... <5> Both exponential functions <4>, <5>, .theta.an _-1 , .theta.sn _-1 ,. Value. θan, θa _n-1: time t _n, the estimated temperature based on the temperature of _{t n-1 [℃] θsn} , θs n-1: time t _n, the estimated temperature based on the solar radiation of _{t n-1 [℃] An} : Measured temperature at time t _n [° C] Sn: Measured solar irradiance at time t _n [KW / m ² ] Δθsmax: Intensity of irradiance saturation temperature increase Ta: Temperature change time constant due to temperature change Ts: Temperature change due to change in solar intensity constant

Then, when the electric wire temperatures θin, θan, and θsn are added according to the following equation (6), the electric wire temperature (estimated temperature) θn at time tn is determined in consideration of the supplied current and the weather conditions.

[0033]

[Equation 6] θn = θin + θan + θsn ... <6>

Prediction of temperature after a certain period of time From a present time (time tn), for example, a certain period of time of about one to several minutes J
Electric wire temperature (predicted temperature) θi _{(n + J1)} , θa based on each of the energizing current, air temperature, and solar radiation intensity at time tn _{+ J1} after one
_{(n + J1)} and θs _{(n + J1)} are parameters Δθimax, (In / Imax) ² , Ti of the exponential function <3> and parameters An, Ta, ΔSmax of the exponential functions <4>, <5>.・ S
n and Ts are fixed to the current values, and tn in the equation is changed to tn _{+ J1} ,
The tn _-1 can be predicted as t _{n-1 + J1.}

Further, the predicted temperatures θi _{(n + J1)} , θ
a _{(n + J1)} and θs _{(n + J1)} are estimated by θin, θa
By substituting the values into n and θsn, it is possible to obtain a predicted temperature θn _{+ J1} after a predetermined time J1 in consideration of the supplied current and weather conditions.

Then, a set time interval (for example, 0.
(5 minutes), the calculations of the expressions <3> to <6> are repeated, and the current estimated temperature at every moment and the predicted temperature after a certain period of time are obtained.

Next, the determination of the necessity of load limitation based on the estimated and predicted wire temperature will be described.

In this embodiment, in order to make a high-precision determination, a first-stage determination level and a second-stage determination level are set as load-limit determination levels, and the load limit is determined by the two-stage determination described below. Determine the presence or absence of sex.

When the electric line is a transmission line, the first-stage judgment level is set to the short-time maximum use temperature (short-time operation level) θ _L of the transmission line, and the second-stage judgment level is set to the first stage judgment level.
Set the dangerous temperature θ _H higher than the step determination level.

Further, the following first, second, and third main conditions and sub-conditions are set as conditions for determining that load limitation is necessary.

First and second main conditions for immediate shut-off based on the second-stage determination level (dangerous temperature θ _H ) (i) First main condition (event 1 determination condition) The estimated temperatures for three consecutive times at times tn _-2 , tn _-1 and tn are θn _-2 , θn _-1 and θn, and the predicted temperatures after a certain time J1 are θn _{-2 + J1} and θn _{-1 + J1.} , Θn
_{+ J1} , the three consecutive predicted temperatures θ
As shown in FIG. 2, n _{−2 + J1} , θn _{−1 + J1} , θn _{+ J1}
Shows a rising tendency (θn _{−2 + J1} <θn _{−1 + J1} <θn _{+ J1} ), and all of them show the second-stage determination level (dangerous temperature θ _H )
That is all.

(Ii) Second Main Condition (Condition for Backing Up Judgment Condition of Event 1) As shown in FIG. 3, for example, as shown in FIG. 3, at time tx, the estimated temperature rises to the second-stage judgment level, and thereafter, The estimated temperature is kept at or above the second-stage determination level.
Time tn _-2 (T
1n _-2 hours), tn _-1 (after T1n _-1 hours), tn (T1n
(After time), the three consecutive estimated temperatures θn ₋₂ , θn ₋₁ , and θn are all equal to or higher than the second-stage determination level. In other words, the estimated temperatures θn ₋₂ , θn ₋₁ , and θn are equal to or higher than the second-stage determination level (dangerous temperature θ _H ). That is, the state continues for a first predetermined time, that is, a predetermined time J2 or more.

Incidentally, in this case is not a condition is to show the estimated temperature rise between them, corresponding to the condition as long as the way downward trend indicates danger temperature theta _H or more as in Figure 3.

A third main condition (judgment condition of event 2) based on the first stage judgment level (maximum allowable temperature θ _L ) This condition has more margin than the first and second main conditions. This is a limiting condition in the state, and as shown in FIG. 4, for example, at time ty, the estimated temperature rises to the first-stage determination level (maximum allowable temperature θ _L ), and thereafter, the estimated temperature is maintained at or above the first-stage determination level. Time tn- ₂ (after T2n- ₂ hours), tn- ₁ (after T2n- ₁ hours) after a predetermined time J3 as a second predetermined time longer than the predetermined time J2 has elapsed from time ty.
tn (after T2n hours) three consecutive estimated temperatures θn _-2 , θ
This means that both n ₋₁ and θn are equal to or higher than the first-stage determination level, in other words, the state that is equal to or higher than the first-stage determination level (maximum allowable temperature θ _L ) continues for a certain period of time J3 or more.

A sub-condition using an excessively large current as a criterion (a condition for judging an emergency current value)
Is greater than or equal to the emergency value Im · βmax.

Here, Im is a reference current value for each wire type.
βmax is an electric wire emergency value coefficient larger than the minimum current guarantee coefficient βmin of the electric line, and both are constant values specific to the electric line.

Under the condition that the temperature is low and the solar irradiance is weak in winter or the like, the above-mentioned predetermined time J
If the predicted temperature after one becomes low, and judging only from the predicted temperature and the estimated temperature, a situation may occur in which the load is not limited even if an excessive current far exceeding the allowable current of the power line flows. Therefore, it is provided to avoid this situation.

Next, with regard to the implementation of this determination method,
This will be described with reference to FIG. In FIG. 1, the temperature determination unit 1 makes a determination based on the first, second, and third main conditions and a next first, second reset determination.

(I) First reset This reset is to release the load limitation based on the first and second main conditions. The condition is that the predicted temperature is once at the second-stage determination level (dangerous temperature θ). _H ), then the predicted temperature θn after a certain time J1 at time tn
_{+ J1} is lower than the second-stage determination level.

If the reset condition is satisfied, it is predicted that the wire temperature will surely be lower than the dangerous temperature θ _H without limiting the load when a predetermined time J1 has elapsed from the present time (tn). , Resetting the judgment output of the second main condition to prevent useless load limitation.

(2) Second reset This reset cancels the load limitation based on the third main condition. The condition is that the estimated temperature is once at the first-stage determination level (the maximum allowable temperature θ _L ). , But then
This means that the predicted temperatures θn ₊ J1 after the predetermined time J1 at the time tn are all lower than the first-stage determination level.

When the reset condition is satisfied,
When the predetermined time J1 has elapsed from the current time (tn), it is predicted that the wire temperature will surely be lower than the maximum allowable temperature θ _L without limiting the load, so that the determination output of the third main condition is reset, and Prevent load shedding.

If the first, second, and third main conditions are satisfied, the logic 1 (hereinafter, referred to as "1") indicating that load limitation is required from each of the AND gates 2, 3, and 4 of the temperature determination unit 1. ) Is output, and if the first and second resets correspond, the temperature determination unit 1 outputs a reset signal of “1”. In addition, the current determination unit 5 makes a determination based on the above-described sub-condition and a next third reset determination.

This third reset cancels the load limitation based on the sub-condition, and the condition is that the current
1.1 times (In · 1.1) is smaller than Im · βmax, and the conduction current In is sufficiently smaller than the emergency value.

If the sub-condition corresponds to the third reset, the current judging unit 5 resets the "1" judgment signal similar to the judgment signal of the AND gates 2 to 4 and resets the first and second reset conditions. A reset signal of "1" similar to the signal is output.

Further, each judgment signal and the reset signal are supplied to the limit command unit 6, and the judgment signals of the AND gates 2 and 3 are latched by the signal holding unit 8 via the OR gate 7, and the reset signal of the first reset condition is set. Is applied to the output OR gate 9 through the signal holding unit 8 until the signal holding unit 8 is reset.

Similarly, the judgment signal of the AND gate 4 is latched by the signal holding unit 10 and is applied to the OR gate 9 via the signal holding unit 10 until the signal holding unit 10 is reset by the reset signal of the second reset condition. Can be

The judgment signal of the current judging section 5 is latched by the signal holding section 11, and the signal holding section 11 is reset until the signal holding section 11 is reset by the reset signal of the current judging section 5.
To the OR gate 9.

Therefore, the OR gate 9 of the restriction command section 6
Outputs a "1" feeder shut-off command until it is canceled by a reset signal when it is predicted that either the main condition or the sub-condition is satisfied and load limitation is required.

Based on the cutoff command, the load control circuit 12
Shuts off each load feeder of the system in order according to a set order or the like.

Therefore, in the case of this embodiment, the second-stage determination level (dangerous temperature θ _H ) at which the load feeder needs to be immediately turned off by the determination of the first main condition is determined based on the predicted temperature after a predetermined time. Presence or absence of the necessity of load limitation is determined predictively on the basis of the reference, and a delay in the determination when the energizing current suddenly reaches the dangerous temperature within a short time is prevented.

At this time, when the temperature of the electric line is accurately estimated and predicted in consideration of weather conditions, and when the predicted temperature is higher than the second-stage determination level three times, that is, a plurality of times in succession. Since it is determined that the load limit is necessary only in the case of, the variation due to the transient variation, disturbance, or the like is excluded, and the determination with high accuracy can be performed.

When the estimated temperature (current temperature) continuously exceeds the second-stage determination level for a certain period of time or longer and has already reached the dangerous temperature, the load limitation is immediately performed by the determination of the second main condition. It is determined that it is necessary.

Further, when the estimated temperature continuously exceeds the first-stage determination level (maximum allowable temperature θ _L ) for a certain period of time or more and there is a possibility that the dangerous temperature will be reached, the load is determined by the determination of the third main condition. Since it is determined that there is a need for restriction, prediction determination with even higher accuracy can be performed than so-called two-stage determination.

Note that the determination of the second and third main conditions also requires that the estimated temperature be equal to or higher than the first and second step determination levels for a plurality of (three) consecutive times. Needless to say, it is possible to eliminate the influence of disturbance and the like.

For this reason, the so-called two-stage judgment based on the first and second stage judgment levels is also used to make a predictive judgment which has not been conventionally performed, so that the judgment of the necessity of load limitation can be accurately made without delay. Based on this determination, the load feeder can be cut off without any excess or shortage, and the amount of current flowing through the power line can be limited so that its temperature becomes the maximum allowable temperature in consideration of weather conditions.

Further, when the amount of supplied current becomes abnormally large, it is determined that the load must be limited by the determination of the sub-condition, and the load feeder is shut off, so that the accuracy of the determination and control is further improved.

When the determination is simplified, the second-stage determination level (critical temperature θ
_H ) and only the first and second main conditions may be determined to determine whether or not there is a load limitation.

The electric wire temperature may be estimated by, for example, a method similar to that of the above-mentioned application. At this time, if the influence of wind is taken into account as a weather condition, more accurate estimation can be performed. Further, the first-stage determination level, the second-stage determination level, and each fixed time may be set in accordance with an electric line or the like.

[0070]

The present invention has the following effects. First, in the case of the first and second aspects, the current flowing through the wire path is
Temperature, air temperature and solar radiation intensity estimated from the generated heat
Add the wire temperature estimated from the heat generation based on the temperature
Current and constant considering the current flowing through the line and weather conditions
Estimating the temperature of the time after the prediction temperature after a certain time estimated indicates a continuous rise, when it is determined that reliably reach a critical temperature in this state, or the estimated temperature of the electric line is a predetermined time When it is determined that the temperature is equal to or higher than the dangerous temperature, a feeder cutoff command can be output by determining that load limitation is necessary without delay by a so-called predictive determination method, and the current flowing through the power line can be reduced. In consideration of the weather conditions , the maximum capacity within the thermal limit can be limited without excess or shortage.

Further, in the case of the third and fourth aspects, the determination of the necessity of the load limitation is made based on the first-stage determination level set to the maximum allowable temperature for short-time use of the electric line and the electric line having a higher level than this level. Rutotomoni provided a two-stage determination level with the second-stage determination level set a critical temperature, as in claim 1, 2
And the current and weather conditions
Estimate the temperature after a certain time .

The weather conditions are determined by the two-stage determination.
Also shows the predicted temperature after a predetermined time continuously increasing tendency of the consideration to electrical lines, when it is determined that reliably reach a critical temperature in this state, the estimated temperature of the electric wire path first predetermined time or more dangerous temperature Not only when it is determined that the above has been reached, but also when there is a possibility that the estimated temperature of the electric wire temperature becomes the maximum use temperature for a short period of time equal to or more than the second predetermined time and eventually reaches the dangerous temperature. determines that there is a need for load shedding, rather late in predictive determination method, moreover, feeder to determine extremely precisely, whether the need for load shedding
It is possible to output a cutoff command, and it is possible to more accurately limit the current flowing through the electric wire path without excess or deficiency than in the case of claims 1 and 2.

[Brief description of the drawings]

FIG. 1 is a block diagram of one embodiment of the present invention.

FIG. 2 is an explanatory diagram of a time change of an electric wire temperature for explaining determination of a first main condition in FIG. 1;

FIG. 3 is an explanatory diagram of a time change of an electric wire temperature for explaining determination of a second main condition in FIG. 1;

FIG. 4 is an explanatory diagram of a time change of an electric wire temperature for explaining determination of a third main condition in FIG. 1;

[Explanation of symbols]

θn _-2, θn _-1, θn estimated temperature _{θn -2 + J1, θn -1 +} J1, θn + J1 predicted temperature theta _L first stage determination level (maximum allowable temperature) theta _H second stage determination level (critical temperature )

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) H02H 6/00 H02H 5/04 H02J 3/00

Claims (4)

(57) [Claims] 1. A judgment level of a load limit of an electric line is set to a dangerous temperature higher than a maximum allowable temperature of the electric line, and a temperature of a generated heat amount based on a current flowing current of the electric line is set.
The amount of rise is calculated based on the energizing current obtained in the previous estimation calculation.
To the estimated temperature, and based on the current
To estimate the current temperature and the temperature after the predetermined time.
Periodically, the temperature and insolation intensity as current weather conditions of
The previous estimation calculation based on the amount of temperature rise based on the generated heat
In addition to the estimated temperature based on the weather conditions obtained in
Road based on the current weather conditions and
The temperature estimation is repeated periodically, and the current and the constant based on the current carrying current of the electric line are
Based on the estimated temperature after time and the current weather conditions of the line,
And the estimated temperature after the predetermined time
From the current energizing current and weather conditions in the period to the electric line as well as estimate the current temperature of the electric line to predict the temperature after the predetermined time, predicted temperature after the predetermined time a plurality of times continuously When the temperature rises above the judgment level or when the estimated temperature of the electric line continuously exceeds the judgment level for a predetermined time or more, it is judged that the load on the electric line needs to be limited and the feeder cutoff command is issued. And a load limit judging method for an electric line. 2. The method according to claim 1, wherein a judgment level of load limit of the electric line is set to a dangerous temperature higher than a maximum allowable temperature of the electric line, and a current level of the electric line based on a current flowing through the electric line is set.
Is estimated from the calculation of the following equation ( 1), and θin = {Δθimax (In / Imax) ^k− θin _-1 }
· [1-exp {- ( t n -t n-1) / Ti}] + θi n-1 =
(Δθi−θi _n−1 ) · {1-exp (−Δt / Ti)} +
θi _n-1 t _n , t _n-1 : n-th (current) and _n-1- th (previous) calculations
Time Delta] t: calculation of the time interval _{(= t n -t n-1} ) θi n, θi n-1: the time t _n, t _n-1 of the estimated temperature In: Detection value of the energization current at time t _n Imax: energizing Current reference value (nominal allowable current value) Δθimax: Saturation temperature rise value at Imax Ti: Temperature change time constant k: Current conversion index The above-mentioned electric wire path based on temperature and solar radiation intensity as weather conditions
Estimate the current temperature from the following two equations (2) and (3)
And, [Equation 2] _{θan = (An-θa n-} 1) · {1-exp (-Δt / Ta)} + θa n-1 Equation 3] 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: the time t _n, t _n-1 of based on temperature estimated temperature θsn, θs _n-1: the time t _n, t _n-1 of the estimated temperature An based on solar radiation: time t _n of the measured temperature Sn: measurement irradiance at time t _n Derutashitasmax: irradiance saturation temperature rise value Ta: change in temperature time constant due to temperature changes Ts: solar irradiance Temperature change time constant due to change The estimated values θin, θan, θsn are added and the
To estimate the current temperature θn (= θin + θan + θsn)
Equation t _n = T _{n + J1} of monitor number to several 3, and _{t n-1 = t n-} 1 + J1
And the temperature θn _{+ J1} (= θi ( _{n + J1} ) + θa after a certain time J1
( _{N + J1} ) + θs ( _{n + J1} ))
Ri returns, when before Ki予 measuring temperature theta _{n + J1} multiple times when continuously rising trend becomes more the determination level or the pre Ki推 constant temperature θn becomes continuously more the discrimination level for a predetermined time or more A feeder cutoff command is output after determining that the load on the wire path needs to be limited, and a load limit determination method for the wire line. 3. The first-stage determination level of the load limit of an electric line is determined.
Short time of the electric line Set to the maximum allowable operating temperature, The second-stage determination level of the load limitation of the electric line is set to the short-time
Set a dangerous temperature higher than the maximum allowable operating temperature, Temperature at the amount of heat generated based on the current carrying current of the electric line
The amount of rise is calculated based on the energizing current obtained in the previous estimation calculation.
To the estimated temperature, and based on the current
To estimate the current temperature and the temperature after the predetermined time.
Periodically repeated, Temperature and insolation intensity as the current weather conditions of the electric line
The previous estimation calculation based on the amount of temperature rise based on the generated heat
In addition to the estimated temperature based on the weather conditions obtained in
Road based on the current weather conditions and
Periodically repeat the temperature estimation, Current and constant based on the current carrying current of the wireway
Based on the estimated temperature after time and the current weather conditions of the line,
And the estimated temperature after the predetermined time
Periodically from the current carrying current of the electric line and weather conditions
Estimate the current temperature of the wireway and after a certain time
Predict the temperature of The predicted temperature after the predetermined time is continuously increasing several times.
When the level exceeds the second-stage judgment level, the
When the constant temperature is continuously longer than the first predetermined time,
Or when the estimated temperature of the wireway is
Continuously before the second predetermined time longer than the first predetermined time
When the level becomes equal to or higher than the first-stage determination level,
Outputs feeder cut-off command when it is determined that load limitation is required
A method for determining a load limitation of an electric line. 4. The first-stage determination level of the load limit of an electric line
Set the maximum allowable temperature for short-time use of the electric line, The second-stage determination level of the load limitation of the electric line is set to the short-time
Set a dangerous temperature higher than the maximum allowable operating temperature, The current of the wire based on the current carrying current of the wire;
Is estimated from the following equation (4), (Equation 4) 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 t _n , T _n-1 : The nth time (this time), _n-1 The first (previous) calculation
Times of Day Δt: calculation time interval (= t _n -T _n-1 ) θi _n , Θi _n-1 : Time t _n , T _n-1 Estimated temperature of In: time t _n Detected current value Imax: Reference value of energizing current (nominal allowable current value) Δθimax: Saturation temperature rise value at Imax Ti: temperature change time constant k: Current conversion index The temperature of the cableway based on temperature and solar radiation intensity as weather conditions
Estimate the current temperature from the following equations (5) and (6)
And (Equation 5) θan = (An−θa _n-1 ) · {1-exp (−Δt / Ta)} + θa _n-1 (Equation 6) 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 temperature based on air temperature θsn, θs _n-1 : Time t _n , T _n-1 Temperature based on solar radiation An: time t _n Measured temperature Sn: time t _n Measured solar radiation intensity Δθsmax: Insolation intensity saturation temperature rise Ta: temperature change time constant due to temperature change Ts: time constant of temperature change due to change of solar radiation intensity Each of the estimated values θin, θan, θsn is added and the
To estimate the current temperature θn (= θin + θan + θsn)
Tn = T in the equations 1 to 3 _{n + J1} , T _n-1 = T _{n-1 + J1}
As the temperature θ after a certain time J1 _{n + J1} (= Θi ( _{n + J1} ) +
θa ( _{n + J1} ) + Θs ( _{n + J1} )) Forecasting periodically
Repeat, The predicted temperature θ _{n + J1} Is continuously increasing several times,
More than two-step judgment level When the estimated temperature θn
Continuously exceed the second stage determination level for at least one predetermined time
Or the estimated temperature θn is equal to the first predetermined time.
The first-stage determination is continuously performed for a longer second predetermined time or longer.
If the load exceeds
It is characterized by outputting a feeder cutoff command when it is determined that there is
The method for determining the load limit of an electric line.