JPS6321151B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a power transmission line phase detection method that can reliably perform phase detection at both ends of a three-phase long-distance power transmission line even in the presence of induced current.

Ground both the sending and receiving ends of the power transmission line for each phase, send an impulse current to each phase from one end, and when this current reaches the other end, determine the polarity and check both terminals of each phase wire. Regarding the phase detection method, one of the applicants of the present invention previously proposed a new method in Japanese Patent Application No. 142032/1983 entitled "Phase detection method for power transmission lines."

However, in normal power transmission lines, commercial frequency alternating current flows due to electromagnetic induction from live circuits installed on the same tower or from nearby parallel transmission lines, and differences in ground potential between the transmitting and receiving ends, and sometimes the value is several times higher. Although they can reach tens of amperes, the elimination of these induced currents can be increased or decreased in practice.

Injecting the original impulse current into such a line by electromagnetic coupling is not practical in terms of economy and handling since the coupling efficiency is low in ironless coupling.

Therefore, one way to increase the coupling efficiency is to use an electromagnetic coupling circuit in which a coil is wound around a ring-shaped magnetic core and the grounding wire is passed through it. However, if the induced current becomes excessive, the magnetic core in this coupling circuit will be affected by the commercial frequency induced current. The transmission efficiency of the impulse current applied in a superimposed manner due to saturation is greatly reduced, making it difficult to send and receive signal impulses.

An object of the present invention is to provide a power transmission line phase detection method that can reliably perform phase detection at both ends of a three-phase long-distance power transmission line even in the presence of induced current.

In order to achieve the above object, the power transmission line phase detection method of the present invention connects both ends of a 3-phase long-distance power transmission line to the ground,
An impulse current is applied to one phase of the sending end by a coupling circuit, and the rising polarity and magnitude of the impulse current reaching each phase of the receiving end are detected by the coupling circuit.
In a power transmission line phase detection method that checks both terminals of each phase, the point in time when the induced current in the transmission line at the sending end is almost zero is detected, and in synchronization with this, the original impulse current is applied, and at the receiving end the current is reached. A phase is detected in which the amplitude of the impulse current is the largest among the three phases and its rising polarity is the same as the original impulse current, and a new impulse current is applied to that phase from the receiving end and sent out.
This device is characterized in that the impulse current sent back from the receiving end is detected at the sending end to confirm the response.

The present invention will be described in detail below with reference to examples.

FIG. 1 is a schematic explanatory diagram of the configuration of an embodiment of the present invention. In the figure, 1 ₁ , 1 ₂ , and 1 ₃ are three-phase long-distance transmission lines that are subject to phase detection, and while both transmitting and receiving ends are grounded, one phase has a transmitter and a discriminator. 2. A receiver 2' (or vice versa) is provided, and the original impulse current is sent from one side and detected from the other side, so that both sides can mutually judge each other. That is, the necessary original impulse current is generated from the transmitter 2, and it is received by the receiver 2'.
At the same time, the arrival of the impulse current is determined based on its polarity and amplitude, and at the same time, an impulse current is separately sent from the receiving end device 2' to the sending end device 2 as a response signal. In this case, if there is an induced current from the other line mentioned above,
Since it is difficult to detect these impulse currents, in the present invention, the phase of the induced current is detected and the original impulse current is injected in synchronization with the zero phase, that is, the point where the current becomes almost zero.

In this case, the induced current is characterized in that it always appears as an alternating current that goes above and below zero. Therefore, this induced current is captured by the detectors 3, 3', its waveform is shaped and used as a control signal, and the original impulse current is sent out at a point in time when this induced current is zero or close to it. Furthermore, by applying an impulse current synchronized to the zero phase point to the sending end, detection at the receiving end is necessarily carried out at the zero phase of the induced current, making it easy to identify the arriving impulse current.

As in the present invention, when an impulse current is sent to one of the three phases from one end of a power transmission line with both ends grounded, the amplitude of the impulse current reaching the other end is the largest in the sending phase, and the amplitude in the other two phases is the same. Approximately 1/3, or the rising polarity of the impulse current, is opposite between the sending phase and the other phases.

Therefore, if the impulse current detection criteria are set at two points, the rising polarity and the amplitude, and the presence or absence of an impulse current is determined based on these criteria, in FIG. It is determined that the original impulse current does not reach the receiving end device 2'' in the state of out-of-phase coupling, that is, the receiving end device 2''. Therefore, since no response pulse is obtained, the transmitter 2 repeats sending while continuing self-oscillation with a period T _N , but in the state of in-phase coupling, that is, the receiver 2', the good pulse current is transmitted by the receiver 2'. It determines that this has been reached, so it emits a response pulse. Then, the self-oscillation state is left and the original impulse current is generated by the response pulse. This is repeated.

2a and 2b are timing diagrams showing the operation of the arrangement of FIG. 1. Figure a shows the case of the above-mentioned out-of-phase coupling, and corresponds to the self-oscillation state with the oscillation period T _N shown in figure a, and the sending pulse of figure a is generated, but the display in figure a is Only the long cycle display timing on the sending end side is shown. Additionally, this can be displayed as a buzzer.

Figure b shows the case of in-phase coupling. In figure b, the original impulse from the transmitter 2 reaches the receiver 2' after time Δt of the line propagation time, and after time t _R ,
The response pulse b in the same figure is sent out. This response pulse reaches the transmitter 2 again after a time tΔ, as shown in FIG.
This operation is repeated until the period t _R + t _S becomes T _N ≪
If we set it so that t _R + t _S , we get b, , in the same figure.
As shown in the figure, short-cycle display timing can be obtained on each of the sending end and the receiving end, and a buzzer display with different tones can be made on the sending end and the receiving end.

In this way, it becomes possible to clearly distinguish between in-phase and out-of-phase.

FIGS. 3a and 3b show specific circuit examples of a transmitting end device and a receiving end device, respectively, which realize the above-mentioned functions.

In the figure, a shows a transmitter. In the case of out-of-phase coupling, oscillation is established by the self-oscillation period T _N of the oscillation circuit 19, and is controlled by the control circuit 20 and displayed on the display device 21. Switched to the sending side by the through sending/receiving switching circuit 13, and the electromagnetic coupling circuit 1
1 to the power transmission line. In this case, since there is no response pulse, this state remains. Next, in the case of in-phase coupling, a response pulse is input from the transmission line from the receiving end, which will be described later, and the transmission/reception switching circuit 13 is switched to the receiving side.
The pulse selection circuit 14 detects the pulse arriving at the sending end as shown in FIG. On the other hand, the induced current on the power transmission line is detected by the detection coil 12, passed through the amplifier 16, the zero phase detection circuit 17 detects the zero phase point, and the pulse shaping circuit 18 creates a gate pulse and supplies it to the control circuit 20. The above-described held pulse reaching the sending end is sent out to the power transmission line as a sending end sending pulse from the electromagnetic coupling circuit 11 through the same path as described above. Note that in the case of in-phase coupling, the oscillation circuit 19 stops after the initial oscillation.

Figure b in the figure shows a receiver, and its configuration is completely the same as that in figure a, except for the oscillation circuit 19. That is, only in the case of in-phase coupling, the sending pulse from the transmitter is inputted to the electromagnetic coupling circuit 11 as a pulse reaching the receiving end as shown in FIG. The induced current on the transmission line is delayed by t _R time and held in the control circuit 20, and the induced current on the transmission line is detected by the detection coil 1, similar to the transmitter shown in FIG.
2, the zero phase detection circuit 17 detects the zero phase point, the pulse shaping circuit 18 creates a gate pulse and supplies it to the control circuit 20, and the receiving end response pulse shown in FIG. 2b is sent out in the same manner as above. The signal is sent from the electromagnetic coupling circuit 11 to the power transmission line through the path, and this procedure is repeated thereafter.

As explained above, according to the present invention, the gate is set so that the sending end sending impulse current of the transmitting end device and the receiving end response impulse current of the receiving end device are synchronized with the zero phase detection point of the induced current of the power transmission line. Because it is installed and sent out, detection with good discrimination is performed without being affected by induced current, and it is not affected by other power transmission lines, etc.
Phase detection can be performed safely and easily with both ends of the line grounded.

[Brief explanation of the drawing]

FIG. 1 is a schematic explanatory diagram of an embodiment of the present invention, FIG. 2 is an operation waveform diagram showing the principle of the embodiment of FIG. 1, and FIG.
Figures a and b show specific circuit examples of the main parts of the embodiment, in which 1 ₁ , 1 ₂ , 1 ₃ are three-phase power transmission lines, 2 is a transmitter,
2', 2'' are receivers, 3, 3', 3'' are detectors, 11
1 is an electromagnetic coupling circuit, 12 is a detection coil, 13 is a transmission/reception switching circuit, 14 is a pulse selection circuit, 15 is a delay circuit, 16 is an amplifier circuit, 17 is a zero phase detection circuit, 1
8 is a pulse shaping circuit, 19 is an oscillation circuit, 20 is a control circuit, 21 is a display circuit, and 22 is a pulse sending circuit.

Claims (1)

[Claims] 1. Ground both the sending and receiving ends of a 3-phase long-distance power transmission line, apply an impulse current to one phase at the sending end using a coupling circuit, and combine the rising polarity and magnitude of the current that reaches each phase at the receiving end. In a power transmission line phase detection method in which both terminals of each phase are detected by a circuit, a point in time when the induced current in the transmission line at the sending end is almost zero is detected, and an original impulse current is applied in synchronization with this, and At the receiving end, one phase is detected among the three phases in which the amplitude of the impulse current that has arrived is the largest and its rising polarity is the same as the original impulse current, and a new impulse current is applied and sent to that phase from the receiving end. A power transmission line phase detection method characterized by detecting the impulse current reversely sent from the receiving end at the sending end to confirm the response.