JPH053211B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for detecting phase differences between multi-wire distribution lines of different systems.

[Conventional technology]

In multi-wire AC distribution lines such as 3-phase 3-wire or single-phase 3-wire, phase names such as R, S, and T are given, and the wiring clearly identifies these phases for power transmission and distribution. However, when performing various types of work on high-voltage distribution lines, in order to avoid power outages as much as possible,
It is desired to separate the work section and supply power from the distribution line of another system to the section on the terminal side.In this case, after connecting the distribution line of the other system to the terminal side, It has become preferable to perform a detachment.

However, when connecting power distribution lines from other systems to the terminal side, if there is a large phase difference between the lines and the other systems, an overcurrent will flow due to the difference in the instantaneous voltages, causing an overcurrent in the power transmission and distribution system. Conventionally, the circuit breaker is tripped, causing an unexpected power outage, so conventionally it has been unavoidable to cut the power out for a short period of time, and then connect the power supply during this period.

[Problem that the invention seeks to solve]

However, it is undesirable to cause a power outage even for a short time in terms of stable power supply, and if the phase difference with other systems is within an allowable range, there is no need for a power outage, so it is easy and reliable. Therefore, there is a growing demand for a method that can detect phase differences between distribution lines of different systems.

[Means for solving problems]

In order to solve the above-mentioned problem, the present invention is constructed by the following means.

That is, an AC waveform obtained from a known specific phase of a multi-wire distribution line is converted into a rectangular wave whose changing point is the zero-crossing point of this waveform, and a carrier wave of a frequency passing through a transmission line is modulated by the rectangular wave. The transmitted signals are transmitted via the transmission line as transmission signals, and the transmitted signals are received via the transmission line at other parts of the distribution line, and the reception output is demodulated to obtain the reception square wave, and the transmission signals are transmitted at other parts of the distribution line. The AC waveform obtained from that phase is converted into a first test square wave whose changing point is the zero-crossing point of this AC waveform, and the transmission delay between this test square wave and the received rectangular wave from modulation to demodulation is After compensating for the time, phase comparison is performed, and this comparison result is stored as a reference value, and the AC waveform obtained from one of the phases in the multi-wire distribution line of another system that exists near the distribution line in other parts. is converted into a second test rectangular wave whose change point is the zero-crossing point of this waveform, and the phase comparison is performed after compensating the transmission delay time between modulation and demodulation of this test rectangular wave and the received rectangular wave. Then, the difference between the test value as a result of this comparison and the stored reference value is determined, and the phase difference with other system distribution lines is detected based on the value of this difference.

[Effect]

Therefore, using a known specific phase in a specific distribution line as a reference, the phase difference with any phase in another part of the same distribution line is stored as a reference value, and in addition, using the known specific phase as a reference, the phase difference between other distribution lines The phase difference between the two systems is determined as a test value, and the difference between the test value and the stored reference value indicates the phase difference between the two systems.

〔Example〕

Hereinafter, details of the present invention will be explained with reference to figures showing examples.

Fig. 1 is a block diagram, and Fig. 2 is a diagram showing waveforms of each part in Fig. 1.
3-phase 3-wire distribution line 1a with S and T phases
1c is stretched to the utility pole 2, and similar distribution lines 3a to 3c are also connected to the utility pole 2 from the substation 3 of other systems.
The utility pole 2 is equipped with a switch 4 such as a vacuum type or air type pole switch or a cut-out switch. 1c and 3a to 3c are each connected in the same phase.

In addition, at a specific location 10 such as a substation or business office, a low voltage AC waveform a is obtained from a specific phase, for example, an R phase, through a transformer 11, and a rectangular wave b whose zero crossing point is a changing point is obtained. A transmitter 1 converts the carrier waves using a converter 12, FSX (frequency shift) modulates both high and low frequency carrier waves using a rectangular wave b using a modulator 13, and converts them into transmission signals, thereby configuring a wireless transmission line.
4, and is transmitted from an antenna 15.

On the other hand, in other parts 20 such as work sites along the distribution lines 1a to 1c, the transmission from the antenna 15 is received by the antenna 21 and the receiver 22, and the received output is demodulated by the demodulator 23 to form a reception rectangle. wave c is obtained, and the delay circuit 24 modulates the modulator 1.
3 to the demodulator 23 is compensated by a delay time td, and a reference rectangular wave d is obtained.

On the other hand, distribution lines 1a to 1c and 3a to 3
For example, the R phase is selected as one of the phases from each of c, and these are sent to the transformer 2 via switch SW ₁ .
5, and before turning on the switch 4, first, with the switch SW ₁ on the A side, a low voltage AC waveform e is transmitted from the distribution line 1a via the transformer 25.
This is converted into an AC waveform e by the waveform converter 26.
The first test rectangular wave f whose changing point is the zero cross point of
This and the reference rectangular wave d are supplied to a phase comparator 27 such as an exclusive OR circuit, the phases of the two are compared, the comparison output g is extracted, and the pulse width of this is
tp is determined by counting clock pulses etc. in the conversion circuit 28 and converted to a reference value of the digital signal. At this time, since the switch SW ₂ is on the A side, it is applied to the first storage circuit 29. A reference value corresponding to the pulse width tp is stored.

Next, if switches SW ₁ and SW ₂ are set to the B side,
This time, an alternating current waveform e is given from the distribution line 3a of another system through a similar system, and this similarly becomes the second test rectangular wave f, and the phase is compared as described above to obtain a comparison output g. It is stored as a test value in the second storage circuit 30 via the conversion circuit 28 and switch _SW2 .

Then, the phase difference detector 31 consisting of a microprocessor, memory, etc.
Perform calculations to find the difference between the reference value and the test value,
In order to send the difference value obtained by this to the display device 32 such as a character display device, specific power distribution lines 1a to 1c are
The phase difference between the distribution lines 3a to 3c of other systems is displayed.

However, in other parts 20, each distribution line 1
It is unspecified which phase among a to 1c and 3a to 3c is connected to the transformer 25, and the phase difference detector 31 performs the calculation shown in the flowchart of FIG. good.

In other words, "θ=" by the reference value θ ₁ and the test value θ ₂
｜θ ₁ −θ ₂ ｜”101, the absolute value difference θ is found, and in the case of three phases, the phase difference between each phase is 120°, and “θ>240°? If "111 is YES," Δθ=θ
−240°” 112 to determine the phase difference Δθ between the systems, and if step 111 is NO, “θ>120°? ”121
In response to YES, perform “Δθ=θ−120°”122,
According to NO in step 121, “Δθ←θ”131
Therefore, θ is set as Δθ and “Δθ transmission”141
The data is sent to the display 32 via "RET" and steps 101 and subsequent steps are repeated.

Therefore, using a specific phase in a specific power transmission/distribution system as a reference, the phase difference between this system and other systems can be easily and accurately determined at a construction site or the like.

Note that the delay time td of the delay circuit 24 can be ignored as the transmission time between the antennas 15 and 21, so the antenna 21 to the display 32 are integrated into a movable or portable type and adjusted at the specific portion 10. This is desirable.

Also, the carrier wave for FSK modulation is the transmitter 1
4 to the receiver 22 is required.

However, the transmission line to be used may be not only a wireless line but also a wired line, and the frequency of the carrier system is selected according to these transmission frequency bands, and depending on the situation, FSK modulation or amplitude modulation can be used. The same applies to devices that perform various types of modulation such as phase modulation. It may be provided between 14 and 14.

In addition, the phase comparator 27 uses a counter that counts clock pulses, and the count is started by whichever of the rectangular waves d and f rises earlier, and the count is stopped by the one that rises later. The value is sent as a comparison output g, and the conversion circuit 28 may be omitted, and the storage circuits 29 and 30 and the phase difference detector 31
The same effect can be achieved even if the functions of θ ₁ and θ ₂ are integrated, and in FIG.
Various modifications are possible, such as performing the calculation in step 101 after performing each calculation separately.

〔Effect of the invention〕

As is clear from the above explanation, according to the present invention, by extracting an AC waveform from any phase in power transmission and distribution lines of different systems, the phase difference between systems can be easily determined using a specific phase in a specific system as a reference. It can be determined accurately and has remarkable effects in various types of construction work on power transmission and distribution lines.

[Brief explanation of the drawing]

The figures show an embodiment of the present invention; FIG. 1 is a block diagram, FIG. 2 is a diagram showing waveforms of various parts in FIG. 1, and FIG. 3 is a flowchart showing the calculation status of phase difference detection. 1, 3... Substation, 1a-1c, 3a-3c...
... Distribution line, 10 ... Specific part, 11, 25 ... Transformer, 12, 26 ... Waveform converter, 13 ... Modulator, 14 ... Transmitter, 15, 21 ... Antenna,
20... Other parts, 22... Receiver, 23... Demodulator, 24... Delay circuit, 27... Phase comparator,
29, 30...Storage circuit, 31...Phase difference detector, _SW1 , _SW2 ...Switch, a...AC waveform,
b... Rectangular wave, c... Rectangular wave received, f... Rectangular wave to be tested, g... Comparison output.

Claims (1)

[Claims] 1 Convert the AC waveform obtained from a known specific phase of the multi-wire distribution line into a rectangular wave whose changing point is the zero cross point of the waveform, modulate the carrier wave of the frequency that passes through the transmission line with the rectangular wave, and then transmit it. transmitting the transmission number as a number through the transmission line, and receiving the transmission number via the transmission line at another part of the distribution line,
The received output is demodulated to obtain a received rectangular wave, and the AC waveform obtained from any phase of the distribution line in the other part is converted into a first test rectangular wave whose changing point is the zero cross point of the AC waveform. After compensating for the transmission delay time between the modulation and demodulation of the test rectangular wave and the received rectangular wave, the phase comparison is performed, and the comparison result is stored as a reference value. The alternating current waveform obtained from any phase of the multi-wire distribution line of another system existing near the distribution line is converted into a second test rectangular wave whose change point is the zero cross point of the waveform, and the After compensating for the transmission delay time between the modulation and demodulation of the test rectangular wave and the received rectangular wave, phase comparison is performed, and the difference between the test value and the reference value as a result of the comparison is determined, and the value of the difference is calculated. A distribution line phase difference detection method characterized by detecting a phase difference with the distribution line of the other system.