SU535649A1 - The way to protect power lines - Google Patents

Description

(54) METHOD FOR PROTECTING POWER LINES

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This invention relates to the field of electrical engineering.

There is a known method of protecting transmission lines by comparing the phases of the industrial frequency at both ends of the protected line and issuing a shutdown signal when the phases of the compared signals 1 coincide. .

The closest to the invention in its technical nature is a method of protecting transmission lines, based on supplying a continuous high-frequency signal to one of the phases and receiving a signal flowing along the line from the other end from all three phases simultaneously. However, this method does not provide testing. the serviceability of the line before switching on requires the allocation of special frequency bands, and the presence of a relay kit at the transmitting end leads to an increase in the time of protection, which generally reduces its reliability s

In order to increase the reliability of protection by eliminating the supply of voltage to the faulty line according to the proposed method, the received signals from the three phases are converted individually in amplitude and phase.

to compensate for the difference in the wave parameters of the three-phase line, summarize and compare the amount with the predetermined setpoint, and in the case of the difference of the amount from this setpoint, give a signal to disconnect the line.

The drawing is a schematic diagram for the implementation of the described method.

The circuit contains power line 1, for one phase of which at the transmitting end

through an attachment device consisting of a barrier 2, a coupling capacitor 3 and an attachment filter 4, a signal is sent from generator 5. At the receiving end, received through connection devices installed on all three phases, the signals are removed and fed to receiving filters 6, tori 7 and 8 amplitudes and phases and a summing device 9. The signal from generator 5 through an attachment filter 4 and a coupling capacitor 3 enters one of the phases of power line 1. This signal propagates along the line, and a minelayer 2 prevents it from entering the substation.

Due to the fact that the constant propagation of different wave channels of the transmission line is different, the signals received at the receiving end on all three phases, the same in frequency, differ in both amplitude and phase. These signals pass

through the coupling capacitors 3 and the attachment filters 4 and by means of the receiving filters 6 are filtered out from interference. Using regulators 7 and 8 of the amplitudes and phases, their ratios are selected so that, being summed up by the summing device 9, the output signal of the latter receives the sum signal of a certain predetermined setpoint.

The presence of a signal at the output of the summing device allows monitoring the health of the entire device and the line.

When damage occurs on the line, the conditions for propagation of signals along the line are violated and the magnitude of the signal at the output of the summing device differs significantly from the setpoint.

The magnitude of the signal at the output of the summing device must be adjusted so that the signal is reliably received in the presence of interference and natural line symmetry breaking from atmospheric influences.

The proposed method makes it possible to eliminate the supply of voltage to the de-energized line by automatically testing it before applying the voltage.

Claims (2)

1. G.V. Mikutsky, V.S. Skitaltsev. "High Frequency Communication over Power Transmission Lines," Energy, 1969, pp. 379-882. 2. E. A. Karpovich. “High Frequency Power Line Protection, 1935, p. 40.