JPH09215180A - Supervisory control method for line - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a decision with no delay by setting a current interruption rate based on an initial decision of load limitation depending on a temperature estimated from weather conditions and performing the second and subsequent interruption of load selectively with a current interruption rate being set at a predetermined minimum rate thereby limiting the load on a line depending on the temperature of line. SOLUTION: A decision section 4 makes a decision whether limitation of load is required or not base on the current temperature of a line estimated while taking account of weather conditions and the trend of predicted temperature at a predetermined time later. When limitation of load is required, an interruption rate determining section 7 increases the interruption rate as the the estimated temperature increases for a first feeder interruption command and an interruption executing section 8 interrupts the feeder selectively. Second and subsequently commands fix the current interruption rate at a predetermined minimum value and the remaining feeders are interrupted selectively. According to the method, over interruption can be prevented without causing any delay in the decision making and the conduction current of line can be farther reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric line monitoring and controlling method for carrying out load limitation based on the thermal limit of an electric line having a twisted wire structure such as an overhead transmission line.

[0002]

2. Description of the Related Art Conventionally, in the supervisory control of an electric line of a stranded wire structure of this kind, it is generally impossible to detect the temperature of the electric wire and directly grasp the thermal limit thereof. Detecting the load, it is determined whether load limitation is necessary or not based on the magnitude of the energizing current. Based on the result of this determination, the feeders on the load side are selectively shut off in a preset order to implement load limitation. .

In this case, the temperature of the electric wire is
The amount of current that can be transmitted (the amount of energizing current) varies depending on the weather conditions such as insolation, for example, due to the thermal limit in summer and winter, so it is necessary to limit the load only from the energizing current based on a constant current value. ， When judging unnecessary, the standard current value is usually set assuming a severe summer, so in winter, the load is limited by the amount of current before reaching the limit, and the electric line is effective. There is an inconvenience that it cannot be used.

On the other hand, the applicant of the present application filed Japanese Patent Application No. 7-67.
As described in the specification and drawings attached to the application for No. 09 application, a temperature monitoring method for an electric line has already been invented, which estimates the current electric wire temperature of this kind of electric line in consideration of the energizing current and the meteorological condition. , Have applied.

In the temperature monitoring method of the above-mentioned application, the estimated value of the internal temperature of the electric wire of the monitoring line is calculated from the energization current of the electric line to be monitored (hereinafter referred to as the monitoring line), and the surrounding temperature such as temperature and insolation intensity is calculated. The calculated value of the wire surface temperature of the monitoring line is calculated from the meteorological conditions, and the temperature difference between the inside and the wire surface of the monitoring line is calculated from the difference between the two estimated values. The temperature difference is calculated by adding the temperature difference.

In this case, since the wire temperature is estimated by considering the temperature inside the wire of the monitoring line and the temperature of the wire surface in consideration of the current flowing through the wire and the weather condition, the current temperature of the monitoring line indicates the weather condition. It is estimated in consideration of

If it is determined whether or not load limitation is required based on this estimated temperature, the determination can be performed under conditions that match the actual wire temperature, and more appropriate load limitation can be performed, as compared with the case where determination is made based on the energized current only. .

[0008]

In the case of the conventional electric line monitoring and controlling method, the current electric wire temperature is estimated in consideration of the weather conditions by the temperature monitoring method of the above-mentioned application, and the load limitation is performed based on the estimated temperature. Even if it is determined whether the load is required or not, it is only necessary to estimate the current temperature of the electric line. Therefore, it is necessary to determine whether load limiting is required until the wire temperature actually exceeds the temperature at which load limiting is required. However, the same applies to the reverse determination, and the determination is delayed.

Therefore, there is a problem in that the load limitation is delayed, and the load limitation is frequently repeated, which causes a so-called hunting phenomenon of control and the like, and there is a problem that an appropriate load limitation cannot be performed.

According to the present invention, based on the current estimated temperature of the electric line in consideration of weather conditions and the predicted temperature after a certain period of time, the required amount of feeders can be cut off quickly and without excess or deficiency to ideally limit the load. The purpose is to do so.

[0011]

In order to solve the above-mentioned problems, in the electric line monitoring and controlling method of the present invention, the electric wire is determined from the current flowing current and the meteorological condition of the electric line by the periodical load limitation judgment. The current temperature of the line is estimated and the temperature after a certain time is predicted, and at least the current estimated temperature of the electric line and the tendency of the predicted temperature after a certain time to change the load based on the thermal limit of the electric line, It is determined based on the first determination that the need is determined by predicting the needlessness in advance, outputting the feeder cutoff command until the load is determined to be unnecessary, and executing the load limitation for each determination required while outputting the feeder cutoff command. The current cut-off rate is set according to the estimated temperature, and the current cut-off rate based on the judgment required for the second and subsequent times is fixed to a predetermined minimum rate, and each feeder that is energized in the electric line is selectively set at the set current cut-off rate. Shut off the wire It limits in accordance with the load temperature of the electric line.

[0012] Therefore, whether or not the load limitation is necessary is determined by predicting in advance from the change tendency of the current estimated temperature and the predicted temperature after a fixed time at least considering the weather conditions of the electric line. There is no delay.

When load limitation becomes necessary, with respect to the first feeder cutoff command, as the estimated temperature at that time becomes higher, the cutoff rate is increased and each feeder is selectively cut off, so that the load can be quickly reduced. Is done.

Further, when the second and subsequent feeder cutoff commands are continuously output, the current cutoff rate for these commands is fixed to a predetermined minimum rate, and the remaining feeders are selectively cutoff, and the cutoffs that have occurred too far. Is prevented, and the current flowing through the electric line is further reduced. Therefore, ideal load limitation is performed quickly and with the excess and deficiency prevented as much as possible.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Regarding one embodiment of the present invention,
This will be described with reference to FIGS. 1 to 10. First, the estimation and prediction of the temperature of the electric line (electric wire temperature) in consideration of the energizing current and the weather conditions will be described.

The estimation and prediction of the electric wire temperature is performed by estimating the present electric wire temperature as described below, and further presuming that the present event (current, solar radiation, temperature, etc.) continues until a predetermined time J1 elapses. To do.

Estimation of Current Temperature In general, the amount of heat generated in an object in a unit time dt (generated heat amount) 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, and The time change of the temperature is performed by using the heat quantity (heat quantity) Q [KW] generated in the object within a unit time, the heat capacity C [KW second / ° C] of the object and the heat dissipation coefficient H [KW / ° C] as parameters. Θ
Assuming that [° C.] and the elapsed time are t [seconds], the following heat transfer equation <1> is obtained.

[0018]

[Equation 1] Q · dt = C · dθ + H · θ · dt (1)

This heat transfer formula <1> is Q / H =
If θmax is given, the general solution θ is expressed by the following equation 2 <2>
Indicated by.

[0020]

## EQU00002 ## .theta. =. Theta.max .multidot. {1-exp (-t / T)} ... <2>

As is clear from the equation <2>, the temperature θ of the object is measured in accordance with a functional equation in which the rising saturation temperature θmax (= Q / H) and the time constant T (= C / H) are constants. t
Changes exponentially with respect to.

The electric wire temperature of the stranded wire electric line also changes with a constant time constant in accordance with the exponential function characteristic of the expression <2> due to the change in the amount of heat, and the electric wire temperature with respect to the temperature θ of the expression <2>. It can be estimated from the temperature calculation of the simple exponential function of.

In this case, if the change in the wire temperature based on the applied current and the change in the wire temperature based on the weather condition are individually predicted and added together, the wire temperature can be estimated in consideration of the applied current and the weather condition.

Then, the current electric wire temperature θin based on the energized current can be estimated by the calculation of the following exponential function expression <3>.

[0025]

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)} + θin ₋₁ ... <3> In the equation, t _n , t _n−1 , ... Are the following respective values.

T _n , t _n-1 : nth time (current time), _n- 1th time (previous time) calculation time [minutes] Δt: time interval of calculation (sampling / control) (= t _n
-T _n-1), for example 0.5 minutes 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 energizing current (nominal allowable current value) [A] Δθimax: Saturation temperature increase 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 approximately 2 in the case of an electric line.

Further, in the above-mentioned application, Δθmax, θ
Although the electric wire temperature is obtained with in as the amount of heat, since the temperature and the amount of heat are in a proportional relationship, the calculation formula for this amount of heat is substantially the same as the exponential function formula <3>.

Next, when the temperature and the insolation intensity are considered as meteorological conditions, the current wire temperatures θan and θsn based on the air temperature and the insolation intensity are expressed by the following equation 4 similar to the exponential function formula <3>.
It can be estimated by the calculation of the exponential function equations <4> and <5> of Equation 5.

[0030]

## EQU00004 ## .theta.an = (An-.theta.an _-1 ) .multidot. {1-exp (-. DELTA.t / Ta)} +. Theta.an _-1 ... <4>

Equation 5] 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 <5> Both exponential equations <4> and <5> have θa _n−1 , θs _n−1 , ...

Θan, θa _n-1 : Estimated temperature [° C.] based on air temperature at times t _n and t _n-1 θsn, θs _n-1 : Estimated temperature based on solar radiation at times t _n and t _n-1 [° C. ] An: Measured temperature at time t _n [° C] Sn: Measured solar radiation intensity at time t _n [KW / m ² ] Δθsmax: Solar radiation intensity saturation temperature rise value Ta: Temperature change time constant due to temperature change Ts: Due to solar radiation intensity change Temperature change time constant

Then, the electric wire temperatures θin, θan, and θsn are added in accordance with the following equation (6) of the estimation calculation formula <6> to calculate the electric wire temperature (time) at time t _n (current) in consideration of the energizing current and the weather condition. Estimated temperature) θ _n is obtained.

[0033]

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

Prediction of temperature after a certain time From the present time (time tn), for example, a certain time J of about 1 to several minutes
Wire temperature (predicted temperature) θi _{(n + J1)} , θa based on the energizing current, temperature, and solar radiation intensity at time tn _{+ J1} after 1
_{(n + J1)} , θs _{(n + J1)} are parameters Δθimax, (In / Imax) ² , Ti of the exponential function formula <3> and parameters An, Ta, ΔSmax of the exponential function formulas <4>, <5>.・ S
Fixing n and Ts to the current values, tn in the formula is tn _{+ J1} ,
We can predict tn- ₁ as tn _{-1 + J1} .

Further, the predicted temperatures θi _{(n + J1)} , θ
a _{(n + J1)} and θs _{(n + J1)} are estimated θin and θa of the calculation formula <6>
By substituting for n and θsn, the predicted temperature θn _{+ J1} after a certain time J1 in consideration of the energizing current and the meteorological condition can be obtained.

Then, the set time interval (for example, 0.
By repeating the calculations of the equations <3> to <6> in 5 minutes), the current estimated temperature at every moment and the predicted temperature after a fixed time from that are obtained.

Next, a description will be given of whether load limitation is necessary or unnecessary based on the estimated and predicted wire temperature.

In this embodiment, in order to make a highly accurate determination, the first stage determination level and the second stage determination level are set as the load limit determination levels, and the load limit is determined by the two-stage determination described below. ， Determine unnecessary.

When the power line is a power transmission line, the first stage determination level is set to the maximum allowable temperature (short-time use level) θ _L of the power transmission line (for example, 100 ° C. for hard copper strands),
The second-stage determination level is set to a dangerous temperature θ _H that is higher than the first-stage determination level (for example, 120 ° C. for a hard copper strand).

Furthermore, as a condition for determining whether load limitation is required,
The first, second, and third main conditions and subconditions described below are set.

First and second main conditions for immediate shutoff using the second stage judgment level (dangerous temperature θ _H ) as a judgment criterion (i) First main condition (judgment condition for event 1) This condition is For example, time tn _-2 , tn _-1 , at 0.5 minute intervals,
Let θn _-2 , θn _-1 , and θn be the estimated temperatures of tn three times in succession,
The predicted temperature after each constant time J1 is θn _{-2+ J1} , θn
Assuming that _{−1 + J1} and θn _{+ J1} , the predicted temperatures θn _{−2 + J1} , θn _{−1 + J1} and θn _{+ J1} for three consecutive times are increasing (θn _{−2 + J1} <Θn _{-1 + J1} <θn _{+ J1} ) and both are the 2nd stage judgment level (hazardous temperature θ _H ).
That is all.

(Ii) Second main condition (condition for backing up the judgment condition of event 1) As shown in FIG. 4, this condition is such that the estimated temperature rises to the second-step judgment level at time tx, for example, and thereafter. The estimated temperature is maintained at or above the second-stage determination level, and from time tx, for example, 1 to
Time tn _-2 (T after the lapse of a certain time J2 of several minutes)
1n _-2 hours later), tn _-1 (T1n _-1 hour later), tn (T1n
After 3 hours, the estimated temperatures θn _−2, θn ₋₁ , and θn are all above the second-stage determination level, that is, above the second-stage determination level (hazardous 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 that the estimated temperature of between which tends to increase, corresponding to the condition as long as the way also shows a downward trend critical temperature theta _H above FIG.

Third Main Condition Using Judgment Level of 1st Stage (Maximum Allowable Temperature θ _L ) (Judgment Condition of Event 2) This condition has a margin more than the case of the first and second main conditions. As shown in FIG. 5, the estimated temperature rises to the first stage determination level (maximum allowable temperature θ _L ) and then the estimated temperature is maintained at or above the first stage determination level, as shown in FIG. , Time tn _-2 (T2n _-2 hours later), tn _-1 (T2n _-1 hour later), t after a lapse of a predetermined time J3 as a second predetermined time longer than the predetermined time J2 from the time ty.
n (after T2n time) three consecutive estimated temperatures θ n _-2 , θ
Both n ₋₁ and θn are equal to or higher than the first-stage determination level, in other words, the state of the first-stage determination level (maximum allowable temperature θ _L ) or higher continues for a certain time J3 or longer.

Sub-Condition Based on Excessive Energizing Current (Evaluation Condition for Current Emergency Value) This condition is the energizing current In at the time tn (current) of the electric line.
Is an emergency value Im · βmax or more.

Im is a reference current value for each wire,
βmax is a 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.

Further, this sub-condition is that the above-mentioned fixed time J1 of the electric line is set under the condition that the temperature is low and the solar radiation intensity is weak such as in winter.
The predicted temperature afterwards becomes low, and if the judgment is made only from the predicted temperature and the estimated temperature, there is a possibility that the load may not be limited even if an excessive current far exceeding the allowable current of the electric line flows. , It is provided to avoid this situation.

Then, whether or not any of these judgment conditions is met is repeatedly judged at a constant time interval ΔT, and it is judged periodically whether or not the load limitation of the electric line based on the thermal limit is necessary. .

Next, the execution of load limitation based on the determination result of whether or not load limitation is necessary will be described. First, when it is determined that the load limitation is necessary, the output of the feeder cutoff command based on this determination and the establishment of other execution conditions satisfy the load cutoff execution condition of the feeder.

The other execution conditions are, for example, the following conditions (a) to (i).

(A) Initial settling is completed (b) Temperature monitoring start setting is completed (c) Initial monitoring exclusion time has elapsed (d) Electric line to be controlled (Surveillance line) has been decided (e) There is no abnormality in the monitoring / control device (f) The circuit breaker to be shut down for priority shutdown is in the closed (ON) state (g) Previous stage (one before) rank) breaker open (off) to be a state (h) that the current estimated temperature .theta.n have the relationship of .theta.n> theta _L with respect to the first-stage determination level (maximum allowable temperature) theta _L (i ) The protection relay is not working

When the cutoff execution condition is satisfied, the feeder on the load side of the electric line is cut off by the following method.

That is, as shown in FIG. 6, the electric line is a bus bar 1 and a plurality of feeders (load lines) 2a on the load side,
2b, 2c, ..., 2z, if the same order cutoff as in the conventional case is to be performed, each feeder 2 is set by initial setting or the like.
The interruption order (rank) of a to 2z is predetermined.

Then, the above-mentioned cutoff execution condition is satisfied, and 1
When the feeder cutoff command for the second time (at the start of execution) is output, the current cutoff rate of the electric line is determined according to the current estimated temperature θn.

This current cut-off rate is obtained by obtaining the current coefficient Fcutn of the coefficient calculation formula <7> of the following equation 7 which determines the current amount after the load of the electric line is limited, and the upper limit coefficient Fcutn set by this coefficient Fcutn is obtained.
Depending on whether it is less than or equal to b (default value), the current coefficient Fcutn or the upper limit coefficient Fb is used as a reference.

[0056]

[Equation 7] _{Fcutn = 1- (θn-θ L} ) / 100 ... <7>

That is, the current coefficient Fcutn is the upper limit coefficient Fb.
When it becomes below (Fcutn ≦ Fb) and it is judged that the required cutoff amount is large, the current cutoff rate is determined to be (1-Fcutn) · 100 (%) and the current coefficient Fcutn is set in order to perform quick load limitation. Is larger than the upper limit coefficient Fb (Fcutn> Fb), and it is determined that the required interruption amount is small, the current interruption rate is set to (1-Fb).
Determine to 100 (%).

Specifically, the electric line is a hard copper stranded wire HDCC.
In this case, assuming that the first stage determination level θ _L is 100 ° C. and the estimated temperature θn at tn is 110 ° C. (θn> θ _L ), the current cutoff rate based on the first determination is that the current Fcutn is 0. Since 9 ≦ Fb, 10 (%) (= 110-10
0). The minimum rate Fb is set to about 0.95, for example.

Then, as shown in FIG. 7, the following (second time)
Until the determination of ΔT (calculation control time interval)
The feeders 2a to 2z are interrupted in order at the settling time interval Tp so that the energization current of the bus bar 1 becomes a current equal to or less than the determined current interruption ratio.

Further, when the feeder cutoff command is continuously output in the second and subsequent determinations due to the shortage of the cutoff amount, each time the feeder cutoff command is output, the current cutoff rate is set to the upper limit in order to prevent the excessive cutoff. The minimum rate (1 corresponding to the coefficient Fb
-Fb) · Fixed to 100 (%), and the order cutoff of the remaining feeders 2a to 2z is repeated within the period ΔT until the next determination.

When the feeder cutoff command is no longer output, the load limitation is terminated, and when a feeder cutoff command is output after an appropriate period longer than the period ΔT, this command is cut off for the first time. As a command, the order of the remaining feeders 2a to 2z is cut off.

The monitoring / controlling device for making the above-mentioned judgment and load limitation is constructed, for example, as shown in FIG.

In FIG. 1, reference numeral 3 is a determination device, which comprises a determination unit 4 and a command output unit 5. Reference numeral 6 denotes a load limiting device, which includes a cutoff rate determination unit 7 and a cutoff execution unit 8.

Further, as shown in FIG. 2, the judging section 4 comprises a main condition judging section 12 having AND gates 9, 10, 11 and a sub condition judging section 13 and a judging output section 14, and this judging output section 14 is an OR gate. 15, 16 and signal holding unit 1
It consists of 7, 18, and 19.

The determining unit 4 operates at a time interval ΔT of 0.5 minutes, for example, and when the AND gates 9, 10, 11 meet the first, second, and third main conditions, a load limit command is issued. A determination signal of the logic 1 (hereinafter referred to as “1”) for use is output to the determination output unit 14.

At this time, the required judgment signals of the first and second main conditions, which are based on the second stage judgment level, are latched in the signal holding section 17 via the OR gate 15 and based on the first stage judgment level. The determination-requiring signal of the third main condition is independently latched in the signal holding unit 18.

The "1" required determination signal latched by both signal holding units 17 and 18 is supplied to the instruction output unit 5 of the next stage via the OR gate 16.

The first reset condition of the judging section 4 is
Even if the estimated temperature once rises to the second-stage determination level (dangerous temperature θ _H ), the predicted temperature thereafter, that is, the predicted temperature θn _{+ J1} after a certain time J1 at time tn becomes lower than the second-stage determination level. Is.

If this reset condition is satisfied,
Since it is predicted that the electric wire temperature when the predetermined time J1 has elapsed from the present (tn) under the current load state is certainly lower than the dangerous temperature θ _H , the signal holding unit 17 is reset and the first and second main conditions are set. The determination-requiring signal of is turned off to prevent unnecessary load limitation.

Further, the second reset condition of the judging section 4 is that even if the estimated temperature once rises to the first step judgment level (maximum allowable temperature θ _L ), the predicted temperature thereafter, that is, the fixed time at the time tn. That is, the predicted temperature θn ₊ J1 after _J1 becomes lower than the first-stage determination level.

If this reset condition is satisfied,
Since it is predicted that the electric wire temperature after the lapse of a certain time J1 from the present (tn) will surely become lower than the maximum allowable temperature θ _L , the signal holding unit 18 is reset to turn off the determination signal of the third main condition. To prevent unnecessary load limitation.

Further, the sub-condition judging unit 13 makes a judgment on the basis of the above-mentioned sub-condition and resets it.

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

If the energizing current becomes an excessive current that satisfies the subcondition, the subcondition judging unit 13 outputs a judgment signal of "1" to the signal holding unit 19 regardless of the wire temperature. The determination signal is sent from the signal holding unit 19 to the OR gate 1
It is supplied to the command output unit 5 via 6.

When the sub-condition is no longer satisfied, the signal holding unit 19 is reset by the reset output of the sub-condition judging unit 13 and the required judgment signal is turned off.

Therefore, when the judgment section 4 satisfies either of the main conditions or the sub-conditions and it is predicted that the load limitation is required, the judgment unit 4 outputs the judgment signal of "1" required until it is canceled by the reset signal. Is output.

Next, the command output unit 5 has AND gates 20 and 21 in a cascade connection as shown in FIG. 1, and the AND gate 20 in the preceding stage receives the determination signal via the OR gate 16 and the reception of power from the terminal 22. Θn> θ for other execution conditions such as middle
_A signal that becomes “1” when each condition except _L is satisfied is supplied, and the determination-required signal during the supply of this “1” signal is supplied to the AND gate 21 in the subsequent stage.

Further, the AND gate 21 is supplied with the output signal of "1" of the AND gate 20 and the signal of "1" when θn> θ _L of the terminal 23, and under the condition of θn> θ _L. When the output signal of the AND gate 20 becomes "1" and the load must be surely limited, the feeder cutoff command of "1" is supplied to the cutoff rate determining unit 7 of the load limiting device 6 at the next stage.

When the feeder cutoff command is supplied, the cutoff rate determining unit 7 immediately calculates the current coefficient Fcutn by calculating the coefficient calculation formula <7>, and Fcutn≤Fb as the first current cutoff rate. If present, the data of the current coefficient Fcutn is output to the cutoff execution unit 8, and if Fcutn> Fb, the current coefficient Fcutn
b is output to the cutoff execution unit 8.

Further, the interruption executing section 8 determines, based on the supplied current coefficient Fcutn and the current flowing current In of the bus bar 1,
After 0.5 minutes, until the next (second) determination timing, the circuit breakers of the feeders 2a to 2z are set to a predetermined settling time interval Tp until the energization current of the bus bar 1 becomes In · Fcutn or less.
To cut off the ranking.

If the determination signal is output from the determination section 4 even at the second determination timing, the cutoff rate determination section 7 determines the current coefficient corresponding to the minimum rate as the current cutoff rate for the second and subsequent times. Fb (fixed value) is output to the cutoff execution unit 8, and the cutoff execution unit 8 waits until the next (third) determination timing until the energizing current of the bus bar 1 is reduced to In · Fb or less. The circuit breakers 2a to 2z are cut off in sequence.

After that, until the determination signal of the determination unit 4 turns off, the interruption rate determination unit 7 outputs the current coefficient Fb as the current interruption rate to the interruption execution unit 8 at each determination timing, and the interruption execution unit 8 next. By the timing of the determination, the circuit breakers of the remaining feeders 2a to 2z are cut off in order, and the energizing current of the bus bar 1 is reduced by an amount corresponding to the current coefficient Fb.

Therefore, from the viewpoint of thermal limit, it is determined whether load limitation of the electric line is necessary or not by predicting the wire temperature in accordance with the actual temperature in consideration of weather conditions.

Further, based on this judgment, each feeder 2a is so arranged that the energizing current of the bus bar 1 is reduced at a larger current cutoff rate as the estimated current temperature θn is higher until the next judgment is made. ~ 2z is cut off, and the load is quickly limited.

Moreover, when the load limitation of the first time is insufficient and the determination results of the second and subsequent times continue to indicate that the load limitation is required, the remaining feeders 2a to 2z are gradually cut off by the current cutoff at a predetermined minimum rate. It is cut off and overloading is prevented.

Therefore, based on the prediction of the wire temperature, appropriate load limitation can be promptly performed without excess or deficiency.

[0087] Then, for example, 200% overload tolerable amount of bus 1 (I _{20 0)} in the electric line in FIG. 6, and the wire and line HDCC100mm ² from hard copper, the line current (preload limit), wind speed, Under the condition that temperature and insolation intensity change with time as shown in FIG. 8 and current changes twice as much as permissible current, and severe weather changes such as wind speed occur, calculation control time interval ΔT = 0.5 minutes, current When the load limitation was simulated by setting the coefficient Fb = 0.96, the results shown in FIGS. 9 and 10 were obtained.

FIG. 9 shows changes in the line current (current flowing) due to load limitation. In FIG. 10, the solid line B indicates the predicted temperature J1 minutes after the current (tn), and the solid line B indicates the estimated temperature at the current (tn). The solid line C indicates the determination required signal (binary signal) based on the first main condition, and this determination required signal is output during 121.5 minutes to 125 minutes.

As is apparent from both figures, the line current of the bus bar 1 is about 840 A (= I ₂₀₀ ) to about 630 at the first load limitation based on the first required determination for 121.5 minutes.
It is quickly reduced to A, and it is based on the second and subsequent judgments required 12
It was confirmed that the load was gradually reduced to about 480 A by the load limitation for up to 5 minutes, and that control hunting did not occur due to the excess or deficiency of the load limitation during that period, and that appropriate load limitation could be performed quickly and without excess or deficiency. .

Further, according to the estimation of the electric wire temperature of this embodiment, the so-called 2 based on the first and second stage judgment levels is used.
With the step judgment, it is possible to accurately judge whether there is a need for load limitation without delay by making a predictive judgment that has not been performed in the past, and based on this judgment, the load feeder is cut off without excess or deficiency, and There is an advantage that the amount of energized current can be limited to the amount of current at the maximum temperature allowed in consideration of weather conditions.

In addition, when the amount of energized current becomes abnormally large, the load feeder is cut off because it is determined that the load must be limited even by the determination of the sub-condition, so that the accuracy of determination and control is further improved.

In order to simplify the determination, the load limitation is performed by making only the determination of the first and second main conditions based on the second-stage determination level (dangerous temperature θ _H ) which is the condition of immediate cutoff. Whether or not is necessary may be determined.

Further, the wire temperature may be estimated by the same method as in the above-mentioned application. Further, as a weather condition, if the influence of wind is added to <Equation 3>, <Equation 4> and <Equation 5> as shown in FIG. 8, more accurate estimation and determination can be performed.

Next, when shutting off each of the feeders 2a to 2z on the basis of the judgment of the load limitation, for example, each feeder 2a
If the energizing currents of 2 to 2z are known, feeders 2a to 2z corresponding to the interrupted amount may be selected and interrupted instead of the interrupted order.

The configuration of each unit in FIG. 1 may be any configuration, and each determination level, time interval ΔT, etc. may be set according to the electric line.

[0096]

The present invention has the effects described below. Whether or not load limitation is necessary is predicted in advance from the tendency of change in the current estimated temperature and the predicted temperature after a certain period of time considering at least the weather conditions of the electric line, which may cause a delay in the conventional determination. Absent.

When the load restriction is required, the cutoff rate can be increased as the estimated temperature at that time becomes higher with respect to the first feeder cutoff command, and each feeder can be cut off selectively. It is possible to limit the load.

Moreover, when the second and subsequent feeder cutoff commands are continuously output, the current cutoff rate corresponding to these commands is fixed to a predetermined minimum rate, and the remaining feeders are selectively cut off, and the excess cutoff is performed. Can be prevented, and the current flowing through the electric line can be further reduced.

Therefore, it is possible to quickly and ideally prevent the excess and deficiency as much as possible and perform the ideal load restriction against the thermal restriction of the electric line.

[Brief description of the drawings]

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

2 is a detailed block diagram of a portion of FIG. 1. FIG.

FIG. 3 is an explanatory diagram of the change over time of the electric wire temperature for explaining the determination of the first main condition of the determination unit of FIG. 1.

FIG. 4 is an explanatory diagram of the change over time of the electric wire temperature for explaining the determination of the second main condition of the determination unit of FIG. 1.

5 is an explanatory diagram of the change over time of the wire temperature for explaining the determination of the third main condition of the determination unit of FIG.

FIG. 6 is a system diagram of an electric line subjected to load limitation in FIG.

FIG. 7 is an explanatory diagram for blocking each feeder of FIG.

FIG. 8 is an explanatory diagram of an example of a current flowing through the electric line of FIG. 6 and weather conditions.

9 is a calculation result diagram of a time change of a line current (carrying current) due to load limitation under the conditions of FIG.

10 is a current estimated temperature of the electric line under the condition of FIG. 8;
It is a calculation result figure of predicted temperature after a fixed time, and time change of a judgment required signal.

[Explanation of symbols]

1 Bus 2a ~ 2z Feeder θn, θn _-1 , θn _-2 Estimated temperature θn _{+ J1} , θn _{-1 + J1} , θn _{-2 + J1} Predicted temperature

Claims (1)

[Claims] 1. A cyclic load limitation is used to estimate the current temperature of the electric line from the current flowing current of the electric line and the meteorological conditions, and at the same time predict the temperature after a certain period of time. From the current estimated temperature and the trend of predicted temperature after a certain period of time, the necessity or non-necessity of load limitation based on the thermal limit of the electric line is predicted in advance and judged, and the need for load limitation is judged to be no need to cut the feeder command. The current cut-off rate based on the first judgment is set according to the estimated temperature by executing the load limitation for each judgment required during the output of the feeder cutoff command. The current cutoff rate based on is fixed to a predetermined minimum rate to selectively cut off each feeder during energization of the electric line at a set current cutoff rate, the load of the electric line depending on the temperature of the electric line. Special to limit Electric line monitoring and control method for collection.