JPS6346822A - Distribution line carrier equipment - Google Patents

Abstract

PURPOSE:To locate a part of a distribution line causing the deterioration ratio of signal by measuring a voltage and a current on a branch point along the distribution line so as to discriminate contents of the defect of the distribution line of the carrier system accurately. CONSTITUTION:The distribution line 3 connected to a distribution transformer 2 of the system is branched and transmitters-receivers 41, 51 connected to loads 4, 5 are arranged at its branch point. Current transformers CT54-1-54-6 and a discriminating means 53 are arranged near the branch point to the load 5 in this system and a transmission means 55 connected to the line 3 is connected to the means 53. The means 53 of the system measures a voltage and a current on the branch point along the line 3 so as to discriminate the state of the defect of the distribution line due to a noise against a sent signal accurately while they are recorded in a memory means thereby locating the part of the distribution line carrier communication causing the deterioration in the signal ratio.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention relates to a power distribution system that uses distribution lines to exchange information on system status and transmit commands between main points and terminal points on a power distribution system. The present invention relates to a wire conveying device.

[Conventional technology]

As power distribution systems develop and the demand for safely and reliably supplying electricity to a large number of consumers increases, the demand for remote centralized operation of large-scale power distribution networks increases, and so-called power distribution automation systems are gaining momentum. .

In this automated system, the target power distribution system (line) is used as a so-called transmission means to exchange information between remote points between the main point (master station side) and each terminal point (slave station side) on the distribution system. Note [1]
It is being done.

Generally, in the distribution line carrier system, the distribution line also serves as a transmission path, so all system phenomena that occur on the distribution line must be regarded as noise when considering the carrier waves that are transmitted and received as signals.

Some of this noise is relatively clear in size and frequency, such as the power of commercial frequency in the grid, but other noises include surges, noise, harmonics, etc. in size, frequency, phase, timing, etc. There are some things that are not clear,
The treatment is not uniform.

In particular, persistent harmonics are often caused by the operation and operation of load equipment connected to the grid, and the time of occurrence,
The duration is also not constant and it is extremely difficult to grasp it.

It is said that high-order harmonics are generated from electrical products that apply power electronics, such as inverters, which are said to be becoming increasingly popular recently, and these harmonics have frequencies close to the carrier wave signals used in the distribution line carrier system. If the above arrangement tr1. This may interfere with the normal operation of the line conveyance system.

There are several possible countermeasures to this problem, but most of them involve changing the specifications and performance of the transport equipment to reduce the effects of high-order harmonics generated by the above-mentioned electrical products, and this is positioned as a definitive countermeasure. This will take some time.

FIG. 11 is a block diagram of a low-voltage power distribution system to which a conventional power distribution line conveyance system is applied. , 5 is a load, and 6 is a separate transmission path for relaying information of a lower system connected to the distribution transformer 2 to a higher-order electric station or office.

The load 4 includes a transmitting/receiving device 41 and a current transformer (hereinafter abbreviated as CT) that measures and inputs current to the transmitting/receiving device 41.
There are 42-1 and 42-2. Further, voltage is also supplied to the transmitting/receiving device 41, and this is done by connecting three wires between the transmitting/receiving device 41 and the branch line 34. This transmitting/receiving device 41
Then, the information about the electrical physical quantities related to the load 4 collected via CT42-1, 2, etc. is frequency modulated, etc.
The signal is transmitted to the receiver 23 via the branch line 34 and the distribution line VT3.

Similarly to the above, from the transmitting/receiving device 51 of load 5, CT52-
4.2, etc., is transmitted to the receiver 23 via the branch line 35 and the distribution line 3. Further, a power electronics application circuit 50 such as an inverter using a thyristor or the like is connected to the load 5, and adjusts the power supplied to the load 5.

In order to exchange information with the above-mentioned transmitting/receiving devices 41 and 51, a receiver 23 and a transmitter 25 are installed as master stations near the distribution transformer 2.
is connected to the receiver 23, and a CT 24-1.24-2 is connected to the receiver 23 for detecting a current signal of the power distribution line.

Next, the general operation in the above configuration will be explained. Based on a command given via the transmission line 6 from a higher-level electrical station or business office, the signal is transmitted from the receiver 23 to the transmitter 25 to the distribution line 3.
When a signal such as a measurement operation is sent to the load side via the load side, this signal is received by the transmitting/receiving device 41 or 51.

Then, when necessary information is collected and generated, it is transmitted from the transmitting/receiving device 41 or 51 in the same manner as above, and is sent to the branch line 34.
．． 35 and the distribution line 3, the signal is transmitted to the receiver 23 via the CT 24-1.2.

[Problem that the invention seeks to solve]

These series of transmission and reception operations will continue to show the originally planned operation unless a special load is connected or disconnected from the grid, but if a special load such as a device with a built-in semiconductor switch circuit 5o such as an inverter is connected. As a result, signal transmission and reception are affected by the harmonics generated by this equipment.

In particular, the harmonics generated by switching include relatively low-order harmonics, which flow from the feeder branch of one source toward the power supply side (main station side), which impedes signal transmission and reception on the main station side. The source feeder cannot be easily identified from the master station side.

In a radial system, determining whether or not a special load is connected each time a feeder branches causes an extremely large amount of time and effort depending on the location of the load, which can lead to failures. The problem was that depending on the situation, countermeasures could remain unaddressed for a long time.

This invention was made in order to solve the above-mentioned problems, and it is possible to identify disturbances caused by persistent high-order harmonics that occur during operation of power electronics-applied electrical products, and to , a distribution line carrier device that determines whether a carrier signal is absorbed or not based on load characteristics for each specific unit of a distribution system, and thereby identifies a portion that causes a reduction in signal transmission ratio in the distribution line carrier. The purpose is to obtain.

[Means for solving problems]

The distribution line carrier device according to the present invention transfers the current flowing through one or more branch points scattered between the power source and the load in the distribution system and the voltage near the branch point to the current and voltage. comprises discriminating means for analyzing the waveform of and determining, when a harmonic component close to the carrier frequency is present, whether it is a shunt of the carrier signal at each branch point t or noise generation from the harmonic generation current source. It is.

[Effect]

The determining means in this invention determines whether the carrier signal is shunted to branch points located between the power source and the load in the distribution system, or whether noise is generated from a harmonic generating current source.
It is possible to accurately distinguish the details of a transmission path defect in a power line transport system, and to identify the portion that causes a decrease in signal transmission ratio.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure is a detailed explanatory diagram of the present invention. In the figure, attention is paid to the branch point where the distribution line 3 branches to the load 5, and the harmonic component current of a certain order at this branch point is 1. ,I,,I
, determine the direction and size as shown.

Generally, when a signal is transmitted upstream from the slave station (load side) to the master station (grid side), there is a characteristic that the signal flows in the direction shown in the second diagram. That is, since the impedance viewed from the distribution transformer 2 toward the grid side is lower than the load impedance, this is as described above.

(i) First, if there is a harmonic ′iYi source,
If load 5 is considered as its own end, the current is ■. is divided toward the grid side and the load side as shown in Figure 2 (a), and for a certain order component I nn = I , , + I 2n
(2, 1).

(H) Next, if the harmonic source is not operating and the harmonic is being sent from a feeder on the load side, if there is a capacitor load, for example, that absorbs the signal to load 5. In this case, the distribution will be as shown in Figure 2 (b),
Similarly, the current is I lIn"I?n Il. (
2,2).

(iii) Furthermore, when a signal absorption similar to the above occurs in the load 5 while transmitting a downlink signal from the grid side to the load side, the distribution as shown in Fig. 2 (c) will occur, and the current will similarly be I on=I , n I 2n
(2, 3).

(iv) If the signal transmission end is on the grid side with the branch point of load 5 as the border, if there is similar signal absorption, the 211d
It is the same as (c), but if only the own end is absorbed, ■ 0 in 2° (2
,,1).

(V) If the signal transmission end is on the grid side with the branch point of load 5 as the border, and if the negative 41j4 other than load 5 also absorbs the signal, I2n≠0, but in this case, It is determined whether there is any problem in signal transmission and reception depending on whether I In≧k (k tolerance).

In short, the current 11. at the point where load branching occurs. .

If we detect I,,I, and determine its size and phase relationship, we can force '? It is possible to determine whether the noise current in the upward direction is generated by the No. 11 current source or if the signal current in the vertical direction is absorbed by a low impedance load for the signal such as a capacitor. In other words, the above-mentioned relationships are used to discriminate between an abnormality (absorption) in the signal distribution and an abnormality (occurrence) in the noise distribution.

FIG. 3 is a block diagram showing a first embodiment of the present invention. In FIG.
6 is a CT provided near a branch point of the distribution line 3 to the load 5, and 55 is a transmission means.

Since the other parts are the same as those in FIG. 11, the same reference numerals are given and the explanation will be omitted.

The discriminating means 53 receives current from the CTs 54-1 to 54-6, and
A voltage is introduced directly from the ff line 3, and a total of 1iI11 is applied internally.
It has functions to perform processing such as , calculation, and judgment.

That is, since a carrier signal component is applied to the power distribution line 3 and distributed, it is detected, the signal wave component is detected, and its magnitude, direction, and (phase) are determined by harmonic analysis or the like. Also, at that time, the upstream current signal passing through this point,
It discriminates the down voltage signal, determines whether it complies with a predetermined protonyl, and intercepts the up and down signals.

Next, this judgment content has a transmission function so that it can be transmitted to the upper master station at an appropriate timing.

With the above combination, the discriminating means 53 performs the method described in the above principle section. It can be determined whether various relationships between l r, + IQ are satisfied. As mentioned above, the determining means 53 is a track transformer,
After detecting the current, processing such as measurement, calculation, and judgment is performed internally. is available and can be fully implemented using this technology and microcomputer technology for digitally processing measurement data.

Next, based on the flowchart in FIG.
The operation of the embodiment will be explained. First, immediately after startup, the basics of the system status are examined, and the voltage, current, and voltage at the system frequency are determined.
Determine whether the power factor, phase, etc. are abnormal (Step 4-
1.4-2).

After this, the presence or absence of the system carrier signal component passing through the branch point is detected by the intermediate determination means 53 (step 4-3).
. If there is a signal wave component in the current passing through the system midpoint or the voltage at the midpoint, the signal/noise discrimination process shown in the separate diagram will be performed (step 4-4.4-5), but if the signal wave component is If not, record the standard noise level around the relevant time and frequency.
i, the old records are deleted, the memory is updated, and preparations are made for detection again (step 4-10).

Next, as a result of signal noise discrimination processing, it is determined whether or not a signal absorption phenomenon has occurred (step 4-
6) A signal absorption phenomenon occurs.

If so, the transmission means 55 reports this to the master station as uplink information, so either the situation is sent or if the signal absorption is significant and it is impossible to send the uplink carrier signal 4B at that point in time, this situation is reported. The signal is stored in the memory of the discriminating means 53 and waits until the signal absorption decreases.

Generally, when signal absorption is significant, not only the upstream signal but also
Since downlink signals are also affected, the occurrence of such a situation can also be detected on the master station side. Therefore, as the intermediate determination means 53, it is sufficient to continue the standby state even if transport (a) is not possible (step 4-1).
1).

In addition, in the signal/noise discrimination process described below, it is determined whether or not noise has occurred (step 4-7), and if it is determined that noise has occurred, it is reported to the master station side as uplink information in the same way as above. Submit your status.

In this case, when the noise is at a high level compared to the signal,
It becomes difficult for the master station to distinguish between signals and noise, but as in the case of signal absorption above, it becomes impossible to receive the upstream carrier signal, and in the end, the master station cannot properly answer back the reception. It will no longer be done.

Therefore, it is meaningless to transmit the situation upstream from the discriminating means 53, so this situation is stored in the memory of the discriminating means 53 and waits until the noise level decreases (
Step 4-12).

Next, the signal/noise discrimination process omitted in the above explanation will be explained with reference to the flowchart of FIG. first,
Harmonic current construction at the branch point. .

1, Detect the level of I (step 5-1)
.

The detected value will be judged in size and level.

If an excessive current is flowing to the slave station side, it is clearly not transmitted from the carrier device, and this may be regarded as noise (step 5-2).

Next, when the 1-branch line current is larger than the upper limit of the slave station current mentioned above, current is flowing from the branch line to the load (or to the power supply), so this can also be considered as noise ( Step 5-3).

Furthermore, when the current in the branch line is larger than a certain value that is smaller than the upper limit of the carrier signal current (this value is determined by the ratio of the power source impedance and the load branch impedance), the upstream signal does not flow to the power source and is branched off. This is because it is leaking towards the line.

It can be considered as signal absorption. This value ' may vary slightly depending on the operating conditions, so it cannot be set very precisely, but it can be used as a rough guide for making a tentative determination (Step 5-4).
.

After this, electrician. , ■□, and Step 2 are compared with each other (step 5-5).

Unless a signal is being transmitted from the load 5 of the branch line 35, the fti current will not be shunted to the power supply load.

Therefore, at this time,■. =I, +1. If the relational expression holds true, this can be regarded as noise (step 5-6)
.

In addition, there is current flowing to the branch line 35 during transmission at the other end, and
These are engineering. If the following relationship is satisfied: = 12-I, then the signal is being absorbed to its own end as seen from this branch line 35 (step 5-7).

Furthermore, if the other end is receiving, that is, transmitting a downlink signal, if these satisfy the relationship III=I, -I2,
As above, the signal is absorbed to its own end (step 5-8).

Such a state can occur even during signal transmission from a terminal installed on the system side of the branch line 35 if capacitive impedance exists in the branch line 35, so this case may also be regarded as signal absorption.

FIG. 6 is an explanatory diagram of the principle of the second embodiment of the present invention, and when paying attention to the branch point where the distribution line 3 branches to the load 5, the following relationships shown in FIGS. 7(a) to (c) are shown. get.

(i) When a harmonic current source is present. . =1. . 10Ln (it) When absorbing the upstream signal to load 5, Ion”Ii
n Ln (iii) In the case of absorbing the downlink signal to the load 5 (including the case of absorbing the signal from another transmitting end on the metropolitan power supply side) ■. . =I 1n - I 2n The above is exactly the same as the first embodiment.

Now, when a signal is transmitted from the transmitter on the load side, the process occurs. S
"I25 1.S When this is superimposed, Inn' = Io5 Inn I 1t, ' = '!, n LS I 2n' = fin I25.

Hereinafter, in correspondence with the above (i) to (■), electrical work will be explained. l
Examining Il' l I2', we get the following.

(i) When noise is occurring If it is a forced current source, most of it will flow to the grid side 2, so 115 = I25 , °・Eng. . ’=I. .

(if) When absorbing the upstream signal, I on' ” I ns + I an+ and I
OA'=I2n'-■□. ′ Generally,■. 5 is a known frequency, so the current is synthesized. . ' can also be analyzed.6 (iii) When absorbing the downstream signal, I on' ” I n5+ I.

and I 1lfi'``Iln'I2n' l
Iln' ==Itn l151Ln' =Ln
It becomes L5, and the work. . It is the same as above that ′ can be analyzed.

In other words, looking at the three cases above, even if a signal is applied separately from another end (or the own end), (i), (
Since the relationship between ii) and (iii) is unchanged, it is an electrician. It is possible to distinguish between the signal and the XI sound more clearly than when measuring l Ill I2.

Furthermore, the signal transmission end is from the outlet of the branch line 35.

Electrician, whether it is on the grid side or the load side. '.

Compare I 2n′ and current I 1n+ I2°,
Needless to say, it can be determined by looking at the increase and decrease.

FIG. 8 shows the configuration of the second embodiment. In FIG. 8, 56 is a variable frequency I= signal generation source.

Even though the signal is transmitted based on the same modulation principle, the fundamental frequency and modulation frequency are changed. The ``axis'' estimates the system and load status from the No. 48 frequency, voltage, and -current distribution on the system obtained using the discriminator 53 and CT 54, and further estimates the status of the system and load, and further estimates the transmission/reception terminals existing at the ends of other load branches. It may be defined as a general-purpose transmitting/receiving device that can cover the frequency assigned to the Ill device within a range that does not impair economic validity.

Therefore, the variable frequency signal generator used here (56
In order to realize the spirit of the present invention, it is more appropriate to make it possible to use the discrimination means 53 and CT 5-1 at other necessary points on the system together with the discrimination means 53 and CT 5-1.

FIG. 9 is a flowchart explaining the operation of the second embodiment, the contents of which are as follows.

When the time comes for the device to start up, first, the system components are measured at the branch point (step 9-1).

Here, it is necessary to determine whether there is an abnormality or not (step 9-2).
If there is no abnormality, an uplink transmission request signal is sent to the master station, and if there is an abnormality, an alarm is generated and standby (steps 9-10). If a reference signal is transmitted in the downstream direction from the master station side, this is detected and the current control of the signal component is performed. T
Ill IZ? Do I+q (step 9-3
~9-5) In this case, in addition to the signal component, a frequency extremely close to the signal is also included in the measurement, although it is noise. Here, ■. . l II. +I211 was required.

Next, the above-mentioned discriminating means 53 and the variable frequency signal generation source 56 transmit an upstream signal having the same frequency as that assigned to the load 5 toward the master station.

In this case, a current distribution of 1°5+L5+IzS occurs as a signal, resulting in the above-mentioned process. . r Lnl ■Superimposed on 2n. That is, T on' ”■.7.+1゜5 I +n' = I xn+I, sl, f1'
= I2°+I2S There is a relationship, and the detection involves detecting the distribution after the above change.

Next, signal/noise discrimination processing begins, the details of which will be discussed separately.At this point, if signal absorption has occurred, an uplink signal indicating that signal absorption has occurred is transmitted to the master station for reporting. (Step 9-8.9-13) 'If AtEf occurs, send a report in the same way! (9-9,
9-14). If absorption 5 occurs frequently, the situation is stored at this end and the terminal waits until the 09 station determines that communication is possible.

Next, the detailed contents of the signal/noise discrimination process will be explained with reference to the flowchart of FIG. 10, with detailed explanation omitted in the above flowchart. In Fig. 10, “normal flow 1
From the detection of 11111+I2 to the determination of whether I+1 is greater than '' (steps 10-1 to 10-4),
Since this is the same as the case of No. 1/noise discrimination processing in the first embodiment, the explanation will be omitted.

Next, after the above-mentioned noise level determination is completed, it is confirmed whether the signal transmission from the branch points has been performed, and then, the electric currents at the three branch points are checked. +rj+Lf! :1llQ set. +1'lL' (step) O - -5, 1O-6).

Also, the measured values of I,', I□I, and M, and the previous measurements carefully. t 111 ■, and the difference is ΔIOI ΔI 1. Set T ΔI2 (Step 1
O-7).

Now, if a forced current is flowing in from the branch point as noise, this current should be used carefully. is unchanged on the load side from the branch point, and -1u5 hardly exists.

ΔI, = Δ12 (Step 1O-8).

Next, there is a circuit that absorbs signals at the branch point, and if signal absorption occurs, it will be different when -1 Nirii No. 11 is present and when the applied signal is applied this time.

The signal increases □〉O Roaring delta engineering. 〉0 ΔIs2>0 becomes.

At this time, it can be seen that the signal is absorbed (step 10-9゜1O-
10). Furthermore, when the signal source is on the power supply side and receives this signal, the upstream signal is sent from the own end (branch end).
If there is absorption, Δwork. 〉0 Δ■,〈0 ΔI 2 < 0, and the same can be determined (step 1.0-11)
.

〔Effect of the invention〕

As described above, according to the present invention, a total of 111 currents and voltages can be measured at branch points along the distribution line! By doing so, there is a harmonic generation current source from the power electronics equipment on the branch line side from the branch point, causing noise to the transmitted signal, and a capacitor (!) on the branch line side.
, rF absorption circuit, and is configured to determine the state in which the transmitted signal is reduced by Jε, so it is possible to accurately identify the nature of the transmission path failure in the power line transmission system, and the signal in the distribution line transmission can be accurately identified. Effects such as being able to identify parts that cause transmission ratio reduction can be obtained.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the principle of a distribution line conveying device according to a first embodiment of the present invention, FIG. 2 is a diagram showing the current direction at a branch point in a conveying state Ia, and FIG. Block diagram 5 showing an example FIG. 4 is a flowchart explaining the operation, FIG. 5 is a flowchart explaining the operation of signal/noise discrimination processing, and FIG. 6 is the power distribution vA conveyance system according to the second embodiment of the present invention. Fig. 7 is an explanatory diagram of the principle of j, Yf, i! of the branch point according to the conveyance state. 8 is a block diagram showing an embodiment of the present invention; FIG. 9 is a flowchart explaining its operation; FIG. 10 is a flowchart explaining the operation of signal/noise discrimination processing; .114 is a block diagram of a conventional power distribution line conveyance device. 3 is a distribution line, 4 and 5 are loads, 53 is a discrimination means, 55
56 is a transmission means, and 56 is a variable frequency signal generation source. In addition, in the figures, the same reference numerals indicate the same or corresponding parts. Patent applicant Mitsubishi Electric Corporation-1□1 To Piguchi 9-8

Claims (4)

[Claims] (1) In a distribution line transport device that uses distribution lines to exchange information on the system status and transmit commands between main points on the distribution system and terminal points, the power supply and load in the distribution system are The current flowing through one or more branch points scattered in the middle of 1. A power distribution line carrying device comprising a discriminating means for discriminating whether a carrier signal is shunted to each branch point or noise is generated from a harmonic generating current source. (2) The power distribution line conveying device according to claim (1), wherein the discriminating means is provided with a memory means for storing the discrimination result. (3) The power distribution line conveying device according to claim (1), further comprising a transmission means for transmitting the determination result to the main point. (4) When there is a harmonic component close to the carrier frequency, applying a carrier wave signal of the carrier frequency from the variable frequency signal generation source to the branch point, and measuring the subsequent current change at the branch point,
Claim 1 is characterized in that it is determined whether noise is generated from a shunt of the carrier signal or a harmonic generation current source.
) The distribution line conveyance device described in item 2.