JPH0787409B2 - Distribution line transportation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is a distribution system for exchanging information on system status and transmitting commands between main points and end points on a distribution system using a distribution line. The present invention relates to an electric wire transportation method.

[Conventional technology]

As the demand for safe and reliable power supply to a large number of customers has grown due to the development of distribution systems, the demand for remote centralized operation of large-scale distribution networks has increased, and so-called distribution automation systems have become a popular opportunity. .

In this automated system, information is exchanged between remote points at the main points (master station side) and end points (slave station side) on the distribution system. As a so-called transmission means, a distribution line transportation method using a target distribution system (line) as a transmission line is attracting attention.

Generally, in the distribution line transportation method, since the distribution line also serves as a transmission line, all systematic phenomena occurring in the distribution line must be regarded as noises when considering the carrier liquid transmitted and received as a signal.

Some of this noise is relatively clear in magnitude and frequency, such as power at commercial frequencies in the grid, but surge, noise, harmonics, etc.
There are some cases where the phase, timing, etc. are not clear, and the handling is not unique.

In particular, many sustaining harmonics are generated by the operation of load equipment that is sustained in the system, and the generation time and duration are not constant, and it is extremely difficult to understand.

It is said that high-order harmonics are generated from electric products to which power electronics are applied, such as inverters, which have been widely spread recently, and this is a frequency close to the carrier signal used in the distribution line carrier system. In this case, an uncertain abnormal phenomenon may occur, and the normal operation of the above distribution line transportation method may be hindered.

There are several possible measures against this, but most of them are types that reduce the influence of high-order harmonics generated by the above electrical products, mainly by changing the specifications and performance of the carrier, and position them as definitive measures. Will take some time now.

FIG. 11 is a block diagram of a low-voltage distribution system to which a conventional distribution line transportation method is applied. In the figure, 2 is a so-called distribution transformer that links the power supply side of the distribution system and the line load, 3 is a distribution line, and 4 is a distribution line. 5, 5 are loads, and 6 is a separate transmission line for relaying the information of the lower system connected to the distribution transformer 2 to a higher-order electric station or business place.

The load 4 includes a transmitter / receiver 41 and a current transformer (hereinafter abbreviated as CT) 42-1, which measures and inputs a current to the transmitter / receiver 41.
There is 42-2. Further, a voltage is also supplied to the transmission / reception device 41, which is performed by connecting three wires between the transmission / reception device 41 and the branch line 34. From the transmitter / receiver 41, the information about the electrophysical quantity regarding the load 4 collected via CTs 42-1, 2 and the like is frequency-modulated and the like, and is sent to the receiver 23 via the branch line 34 and the distribution line 3. Send.

Similar to the above, information about the load 5 collected from the transmitter / receiver 51 of the load 5 via CTs 52-1, 2 and the like is provided to the branch line 3
5. Send to the receiver 23 via the power 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 the power supplied to the load 5 is adjusted.

In order to exchange information with the transmission / reception devices 41 and 51, a receiver 23 and a transmitter 25 are connected as a master station in the vicinity of the distribution transformer 2, and the receiver 23 is for detecting a current signal of a distribution line.
CT24-1, 24-2 are connected.

Next, a schematic operation in the above configuration will be described. Based on a command given from a higher-level electric station or business office via the transmission line 6, a signal such as a measurement operation is issued from the receiver 23 to the load via the transmitter 25 and the distribution line 3. Then, this signal is received by the transmission / reception device 41 or 51.

Then, when necessary information is collected and generated, it is transmitted from the transmission / reception device 41 or 51 in the same manner as described above, and the signal is sent to the receiver 23 via the CTs 24-1, 2 via the branch lines 34, 35 to the distribution line 3. To transmit.

[Problems to be solved by the invention]

In this series of transmission / reception operations, a special load is connected to the grid,
If it is not disconnected, it will continue to show the originally planned operation, but if a special load such as an inverter or other device containing the semiconductor switch circuit 50 is connected, it will be affected by the harmonics generated by this device and signal transmission and reception will be hindered. To be done.

In particular, harmonics generated by switching have relatively low harmonics and flow from the feeder branch of the generation source toward the power supply side (master station side), so that signal transmission / reception is hindered on the master station side. This source feeder cannot be easily identified from the parent station side.

In the radial system, if each time the feeder branches, it is necessary to discriminate whether or not such a special load is connected, and it will take an extremely large amount of time and labor depending on the position of the load. Depending on the situation, there was a problem that the situation would change without taking measures for a long time.

The present invention has been made to solve the above-mentioned problems, and it is possible to identify a fault due to a persistent high-order harmonic generated during operation of an electric appliance for power electronics application, and a line constituting a system. , It is determined whether the carrier signal is absorbed or not according to the characteristics of the load, for each specific unit of the distribution system, and thus, the distribution line transportation method for identifying the part that causes the signal transmission ratio reduction in the distribution line transportation. Aim to get.

[Means for solving problems]

A distribution line conveying method according to the present invention measures a current flowing at one or more branch points scattered in the middle of a power source and a load in a distribution system and a voltage near the branch point, and waveforms of the current and the voltage. When a harmonic component close to the carrier frequency exists, it is determined whether the shunt of the carrier signal to each branch point or the noise generation from the harmonic generating current source is analyzed.

[Action]

The distribution line conveying method in the present invention conveys a power line by determining whether a carrier signal is shunted to branch points scattered between power sources and loads in a distribution system or noise is generated from a harmonic generation current source. The contents of the system transmission path failure can be accurately discriminated, and the part that causes the deterioration of the signal transmission ratio is specified.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. First
The figure is a diagram for explaining the principle of the present invention.
Attention is paid to a branch point branching from the power distribution line 3 to the direction and magnitude of harmonic currents I ₀ , I ₁ , and I ₂ of a certain order at this branch point, as shown in the figure.

Generally, when a signal is transmitted from the slave station side (load side) to the master station side (system side) upstream, there is a characteristic that the signal flows in the direction shown in FIG. In other words, the impedance as viewed from the distribution transformer 2 on the system side is lower than the load impedance, and therefore, the above is the case.

(I) First, if a harmonic current source is present, load 5
Assuming that the current is the self-end, the current I ₀ is divided toward the system side and the load side as shown in Fig. 2 (a), and I _0n = I _1n + I _2n (2.1) for a certain order component.

(Ii) Next, if the harmonic current source is not operating and is being sent from a feeder on the load side,
When there is, for example, a capacitor load that absorbs a signal to the load 5, the distribution is as shown in FIG. 2 (b), and similarly, the current becomes I _0n = I _2n −I _1n (2.2).

(Iii) Furthermore, when the signal absorption similar to the above occurs in the load 5 during the downlink signal transmission from the system side to the load side,
The distribution is as shown in Fig. 2 (c), and similarly the current is I _0n = I _1n −I _2n (2.3).

(Iv) When the signal transmission end is on the system side with the branch point of the load 5 as a boundary, if there is similar signal absorption, it is the same as in FIG. 2 (c), but only for the self end. For example, I _2n ≈ 0 (2.4).

(V) If the signal transmitting end is on the system side with the branch point of the load 5 as a boundary and the load 4 other than the load 5 also absorbs the signal, I _2n ≠ 0, but in this case Determines whether I _1n ≧ k (k allowable value) or not and whether or not there is a problem in signal transmission / reception.

In summary, if the currents I ₀ , I ₁ , and I ₂ at the point where the load branch occurs are detected, and their magnitude and the mutual system are discriminated, the generation of the noise current in the upward direction by the forced current source, the capacitor, etc. It is possible to judge whether the vertical signal current is absorbed by the low impedance load for the signal. That is, the above relationships are used to discriminate between abnormalities in signal distribution (absorption) and abnormalities in noise distribution (occurrence).

FIG. 3 is a block diagram showing a first embodiment of the present invention. In FIG. 3, reference numeral 53 is a discriminating means, and 54-1 to 54-6 are provided in the vicinity of a branch point of the distribution line 3 branching to the load 5. CT,
Reference numeral 55 is a transmission means, and the other parts are the same as those in FIG. 11, so the same reference numerals are given and description thereof is omitted.

The discrimination means 53 outputs the current from the CTs 54-1 to 5-6 to the distribution line 3
It has a function of directly introducing a voltage from the inside and performing processing such as measurement, calculation and judgment internally.

That is, since the carrier signal component is applied and distributed to the power distribution line 3, this is detected, the signal wave component is detected, and the magnitude, direction, and (phase) thereof are obtained by the harmonic distribution or the like. At that time, the upstream current signal passing through this point,
The downstream voltage signal is discriminated, it is judged whether or not it complies with a predetermined protocol, and the upper and lower signals are intercepted.

Next, this determination 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 determining means 53 can determine whether or not the various relationships among I ₀ , I ₁ , and I ₂ described in the section of the principle are satisfied. As described above, the determining means 53 internally performs processing such as measurement, calculation and determination after detecting the line voltage and current, but these are usually commercially available as harmonic measuring instruments of the power system. However, it is possible to obtain the one having sufficient performance in practical use, and it is possible to sufficiently implement this technology and the microcomputer technology for digitally processing the measurement data.

Next, based on the flowchart of FIG.
The operation of the embodiment will be described. First, immediately after start-up, the basics of the system state are measured to determine whether the voltage, current, power factor, phase, etc. at the system frequency are abnormal (step 4-1).
4-2).

After that, the presence or absence of the system carrier signal component passing through the branch point is detected by the intermediate discriminating means 53 (step 4-3).
If there is a signal wave component in the current passing through the system intermediate point and the voltage at the intermediate point, the signal / noise discrimination processing of another figure is performed (steps 4-4, 4-5), but the signal wave component is If not, accumulate a record of the noise level around the time and frequency,
The old record is erased and the description is updated to prepare for detection again (step 4-10).

Next, as a result of the signal noise discrimination processing, it is discriminated here whether or not the signal absorption phenomenon has occurred (step 4-
6) If the signal absorption phenomenon has occurred, the transmission means 55 notifies the master station side as upstream information by the transmission means 55.
If the situation is transmitted or the signal absorption is so great that the upstream carrier signal cannot be transmitted at that time, this situation is stored in the memory of the discriminating means 53, and the process waits until the signal absorption becomes small.

Generally, when signal absorption is significant, not only the upstream signal,
Since the downlink signal is also affected, the occurrence of such a situation can be detected by the master station side. Therefore, as the intermediate determining means 53, it is sufficient to continue the standby state even if transmission is impossible (step 4-11).

Further, in the signal / noise discrimination processing described later, it is discriminated whether or not noise is generated (step 4-7), and when it is discriminated that noise is generated, in the same manner as above, in order to notify the parent station side as uplink information. Send status. In this case, when the noise is at a higher level than the signal, it is difficult to distinguish the signal from the noise on the master station side, but like the case of the above signal absorption,
Since it becomes impossible to receive the upstream carrier signal, the answerback of the reception cannot be properly performed from the master station side.

Therefore, since it is meaningless to send the situation upward from the discriminating means 53, 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 processing omitted in the above description will be described with reference to the flowchart of FIG. First,
The levels of the harmonic component currents I ₀ , I ₁ , and I _{2 at} the branch point are detected (step 5-1). The detected value is subsequently judged to be large or small and the level. If an excessive current is flowing to the slave station, it is obviously not transmitted from the carrier device,
This may be regarded as noise (step 5-2).

Next, when the branch line current is larger than the upper limit value k of the slave station side current, it means that the current is flowing from the branch line to the load (or to the power supply), so that it may be considered as noise at this time as well. (Step 5-3).

Further, when the current of the branch line is larger than a certain value k'which is smaller than the carrier signal current upper limit value k (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 side. Since it is leaking and flowing toward the branch line, it can be regarded as signal absorption. This value k ′ cannot be set very strictly because there is a slight change in the operating state, but it serves as a guide for making a tentative decision (step 5-4).

Then, the instantaneous value components of the currents I ₀ , I ₁ , and I ₂ are compared with each other (step 5-5).

Unless the signal is transmitted from the load 5 of the branch line 35, the above current will not be shunted to the power source load. Therefore, at this time,
If the relational expression of I ₀ = I ₁ + I ₂ is established, this may be regarded as noise (step 5-6).

Also, if there is a current to the branch line 35 during transmission at the other end, and if these satisfy the relationship of I ₀ = I ₂ −I ₁ , the signal is absorbed from the branch line 35 to its own end. (Step 5-7).

Further, if the other end is receiving, that is, if they satisfy the relationship of I ₀ = I ₁ −I ₂ during downlink signal transmission, it means that the signal is absorbed to its own end similarly to the above (step 5). −
8).

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

FIG. 6 is a diagram for explaining the principle of the second embodiment of the present invention. Focusing on the branch point branching from the distribution line 3 to the load 5, the following relationships shown in FIGS. To get

(I) When a harmonic current source is present I _0n = I _1n + I _2n (ii) When an upstream signal is absorbed by load 5 I _0n = I _2n −I _1n (iii) When a downstream signal is absorbed by load 5 (Including a case where a signal from another transmitting end on the power supply side is partially absorbed) I _0n = 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, I _0S = I _2S −I _{1S When} this is superimposed, I _0n ′ = I _0S −I _0n I _1n ′ = I _1n −I _1S I _2n ′ = It becomes I _2n −I _2S .

Hereinafter, in correspondence with the above (i) to (iii), the current I ₀ ′,
Examining I ₁ ′ and I ₂ ′ gives the following.

(I) When noise is generated If the source is a forced current source, most of it flows to the system side 2, so I _1S = I _2S ∴I _0n ′ = I _0n (ii) When absorbing the upstream signal I _{0n '= I 0S + I 0n} , and, I _0n' in = I _2n '-I _1n' general, because I _0S are known frequency, and current combining
I _0n ′ can also be analyzed.

(Iii) When absorbing a downstream signal I _0n ′ = I _0S + I _0n and I _0n ′ = I _1n ′ −I _2n ′, I _1n ′ = I _1n −I _1S , I _2n ′ = I _2n −I
_{It is 2S} , and I _0n ′ can be analyzed, as above.

That is, regarding the above three cases, even if a signal is separately applied from another end (or its own end), (i), (ii),
Since the relationship of (iii) is invariable, it becomes possible to more clearly discriminate the signal / noise from the case where the currents I ₀ , I ₁ , and I ₂ are measured.

Further, whether the signal transmitting end is on the system side or the load side from the outlet of the branch line 35 depends on the currents I _1n ′, I _2n ′ and the currents I _1n , I _2n.
It goes without saying that it is possible to determine by comparing and and seeing the increase and decrease.

FIG. 8 shows the configuration of the second embodiment. In FIG. 8, reference numeral 56 is a variable frequency signal generation source, so that the fundamental frequency and the modulation frequency can be changed even if the signal transmission is based on the same modulation principle. It is the one.

Therefore, the state of the system and the load is estimated from the distribution of the signal frequency, voltage, and current on the system obtained using the discrimination means 53 and CT54, and the assigned frequency of the terminal transceiver existing at the end of another load branch is determined. It may be defined as a general-purpose transceiver that can cover the economical validity.

Therefore, it is more appropriate to realize the purpose of the present invention that the variable frequency signal generation source 56 used here can be used at other necessary points on the system together with the discrimination means 53 and CT54 used at the same time. is there.

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

At the time when the device is activated, first, various system quantities are measured at the branch point (step 9-1). Here, it is determined whether or not there is an abnormality (step 9-2), and if there is no abnormality, an upstream transmission request signal is once transmitted to the master station side,
If there is an abnormality, an alarm is generated and the system stands by (step 9).
-10). If a reference signal is transmitted in the downstream direction from the master station side, it is detected and the currents I ₀ , I ₁ , and I ₂ of the signal components are measured (steps 9-3 to 9-5). In this case, in addition to the signal component, although it is noise, the frequency that is extremely close to the signal is also measured. Here, I _0n , I _1n , and I _2n are obtained.

Next, the determination unit 53 and the variable frequency signal generation source 56 described above transmit the upstream signal having the same frequency as the load 5 to the master station.

In this case, current distributions I _0S , I _1S , and I _2S are generated as signals, and are superimposed on the above-mentioned I _0n , I _1n , and I _2n . That is, there is a relation of I _0n ′ = I _0n + I _0S I _1n ′ = I _1n + I _1S I _2n ′ = I _2n + I _2S, but the detection is to detect the distribution after the change.

Next, the signal / noise discrimination processing is entered, but the details will be described separately here. If signal absorption has occurred, it is transmitted to the master station side as an upstream signal indicating that absorption has occurred. (Steps 9-8, 9-13), if noise is generated, report transmission is similarly performed (9-9, 9-14). Also, when absorption and occurrence are severe, the situation is memorized and accumulated at this end,
Wait until the master station determines that communication is possible.

Next, the specific contents of the signal / noise discrimination processing, which has not been described in detail in the above-mentioned flowchart, will be described with reference to the flowchart in FIG. In FIG. 10, the currents I ₀ , I ₁ , I ₂
From detection to decision I ₀ is k 'of greater than or not (step 10-1 to 10-4) will be omitted because it is same as that of the signal / noise determining process in the first embodiment .

Next, after the noise level determination is completed, it is confirmed whether or not a signal is transmitted from the branch point, and thereafter, the currents I ₀ , I ₁ , and I ₂ at the three branch points are measured to obtain I _0. ′, I ₁ ′, I ₂ ′ (steps 10-5, 10-6).

In addition, the measured values of I ₀ ′, I ₁ ′, I ₂ ′ and the previous measured values I ₀ , I ₁ ,
I ₂ is compared, and the differences are set as ΔI ₀ , ΔI ₁ , and ΔI ₂ (step 10-7).

Now, if a forced current flows in from the branch point as noise, this current value I ₀ is invariable on the load side from the branch point, and I _0S can hardly exist, so ΔI ₁ = ΔI ₂ (Step 10-8).

Next, there is a circuit that absorbs a signal at the branch point, and if signal absorption occurs, when there is an upstream signal,
When the applied signal is applied this time, the signal component increases and ΔI _S1 > 0 naturally ΔI _S0 > 0 ΔI _S2 > 0.

At this time, it can be seen that the signal is absorbed (steps 10-9, 10-10).
Furthermore, when the signal source is on the power supply side and this signal is received and then an upstream signal is transmitted from its own end (branch end), if there is absorption, ΔI ₀ > 0 ΔI ₁ <0 ΔI ₂ <0, and the same determination is possible. (Step 10-11).

〔The invention's effect〕

As described above, according to the present invention, by measuring the current and voltage at the branch point along the distribution line, there is a harmonic generation current source by the power electronic device on the branch line side from the branch point, and the transmission signal Since it is configured to determine the state of being a noise and the state in which there is a signal absorption circuit such as a capacitor on the branch line side and the transmission signal is shunted, the harmonic current source near the transmission signal frequency And the transmission signal leakage can be confirmed to accurately discriminate the contents of the transmission path failure, and the remarkable effect that the portion causing the signal transmission ratio reduction in the distribution line transportation can be specified can be obtained. .

Further, at the time of transmission of the discrimination effect, if transmission is not possible, the discrimination result is stored in the memory until it can be transmitted.
The determination result can be reliably transmitted, and this transmission can be transmitted to the main points.

Moreover, when there is a harmonic component close to the carrier frequency, the carrier signal of the carrier frequency is applied from the variable frequency signal generation source to the branch point, and the current change at the branch point after the application of the carrier signal is measured. Then, it is determined whether the shunting of the carrier signal or the noise generation from the harmonic current source is performed, and it is possible to more reliably identify the harmonic current source and confirm the transmission signal leakage.

[Brief description of drawings]

1 is an explanatory view of the principle of a distribution line carrying method according to a first embodiment of the present invention, FIG. 2 is a view showing a current direction at a branch point according to a carrying state, and FIG. 3 is a first embodiment of the present invention. 4 is a block diagram showing the operation, FIG. 4 is a flow chart for explaining the operation, FIG. 5 is a flow chart for explaining the operation of the signal / noise discrimination processing, and FIG. 6 is a distribution line conveying method according to the second embodiment of the present invention. FIG. 7 is a diagram for explaining the principle, FIG. 7 is a diagram showing a current direction of a branch point according to a carrying state, FIG. 8 is a block diagram showing an embodiment of the present invention, FIG. 9 is a flow chart diagram for explaining the operation, and FIG. FIG. 11 is a flow chart for explaining the operation of the signal / noise discrimination processing, and FIG. 11 is a block diagram for explaining a conventional distribution line conveying method. 3 is a distribution line, 4 and 5 are loads, 53 is a discrimination means, 55 is a transmission means, and 56 is a variable frequency signal generation source. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (4)

[Claims] 1. A main point and a terminal point on a distribution system,
In a distribution line carrying method for exchanging information on a system state and transmitting a command using a distribution line, a current flowing at one or more branch points scattered between a power source and a load in the distribution system and the branch Measure the voltage near the point and analyze the waveform of this current and voltage to detect the presence or absence of harmonic components close to the carrier frequency.If there are harmonic components, the carrier signal to each branch point is detected. A distribution line carrying method, characterized in that it is discriminated whether the shunt current is generated or noise is generated from a harmonic generation current source. 2. The distribution line carrying method according to claim 1, wherein when the determination result is transmitted, if the determination result cannot be transmitted, the determination result is stored in a memory. 3. The distribution line carrying method according to claim 1, wherein the determination result is transmitted to the main point. 4. When a harmonic component close to the carrier frequency exists, a carrier signal of the carrier frequency is applied from a variable frequency signal source to a branch point, and a current change at the branch point after the carrier signal is applied. The distribution line conveying method according to claim (1), characterized in that the shunt of the carrier wave signal is measured to determine whether noise is generated from a harmonic generation current source.