SU1370630A1 - Device for detecting damaged section of electric mains in case of single-phase ground fault - Google Patents

Abstract

The invention relates to electrical engineering and makes it possible to increase the reliability of determining a damaged part of a network. The device contains startup and switching and coding blocks I and 2, a matching transformer 3, a harmonic filter 4, a rectifier 5, a maximum voltage level fixing unit 7, blocks 8 and 9 of memory and information transfer, and a reproducing unit 10. The introduction of a voltage accumulator II, a voltage divider 12, diodes 6 and 13 expands the control zone to the substation buses. 1 il. with (L

Description

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The invention relates to electrical engineering, in particular, to devices for determining the location of damage in electrical networks, and can be used to determine the damaged area in a single-phase short circuit to earth in radial electric networks with insulated and compensated neutral.

The purpose of the invention is to increase the reliability of determining the damaged part of the network by expanding the control zone to substation buses.

The drawing shows a block diagram of a device for determining a damaged section of an electrical network in a single-phase short circuit to earth.

The device contains a startup unit 1, a switching unit 2 and a coding matching transformer 3, a high harmonic filter 4, a rectifier 5, a first diode 6, a maximum voltage level fixing unit 7, a memory unit 8, an information transfer unit 9, a reproduction unit 10, a voltage adder 11, a voltage divider 12 and a second diode 13. The input group of the start-up unit 1 is connected to the terminals intended to be connected to the outputs of voltage transformers of substation bus sections, and the output is connected to the first input of the switching unit 2 and coders audio, a group of inputs of which is connected with output means for connection to a residual current transformer controlled lines. The first output of the switching and coding unit 2 is connected to a serially connected matching transformer 3, high harmonic filter 4 and rectifier 5 with the anode of a primary diode 6, the cathode of which is connected to the input of the maximum voltage level fixing unit 7, which is connected to the first input of the unit 8 memory, to the second input of which the second output of the switching and coding unit 2 is connected. The output of the memory block 8 through the information transmission block 9 is connected to the input of the reproduction block 10. The output of the rectifier 5 is also connected through the voltage-connected voltage accumulator 11 and the voltage divider 12 to the input of the switching and coding unit 2 having the last sequence number, the third output of the switching unit 2 and

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coding is connected to the anode of the second diode 13, the cathode of which is combined with the cathode of the first diode 6 and the input of the block 7 for fixing the maximum voltage level.

The device works as follows.

When an earth fault occurs, a signal appears at the output of at least one transformer of the voltage section of the substation busbar, and the starting unit 1 is triggered. Switching and coding unit 2 begins to work, alternately connecting zero-sequence current transformers of monitored lines (not shown) to matching transformer 3. Switching and coding unit 2 also prepares circuits in memory block 8 for storing, if necessary, a conventional number assigned to each monitored line and bus substation. The total levels of the higher harmonics of the zero sequence currents of each line are converted by means of a matching transformer 3, a filter 4 of the higher harmonics and the rectifier 5 to constant voltages. The maximum voltage level fixing unit 7 performs a comparison operation of the voltage currently applied to its input from the rectifier 5 through the first diode 6, with the largest voltage applied earlier. If the voltage at the input of the maximum voltage level fixing unit 7 is greater in magnitude than any of the previously submitted ones, then in the memory block 8 the previous information is triggered and a new one is recorded as an encoded line number for which the total harmonics are currently current circuit to earth the greatest.

In the process of alternately connecting current transformers of zero-sequence monitored lines to the matching transformer 3, the signals from the output of the rectifier 5 are also fed to the input of the voltage adder 11. As a result, at the end of this process, a signal appears at the output of the adder of 11 voltages equal to the sum of all voltages removed from the output of rectifier 5. This signal, reduced by a factor slightly exceeding 2, divides the 12 voltage into the input switching and coding unit 2 having the last sequence number. The same signal from the third output of the switching and coding unit 2 through the second diode 13 is fed to the input of the fixing unit 7 of the maximum voltage level. If a ground fault occurs on any line, then the voltage at the output of the divider 12 voltage is less than the highest of the rectifier 5 removed from the output, so in memory block 8 the number of the line with the maximum total harmonics remains closures, i.e. damaged line. If a ground fault occurs on the substation buses, the voltage at the output of the voltage divider 12 is greater than any one of the output from the output of the rectifier 5, and in the memory block 8 a number is recorded corresponding to the substation buses.

At the end of the work of the switching and coding unit 2, from its second output, a command is sent to the memory unit 8 allowing the transmission of the number of the damaged network section using the information transmission unit 9 to the control center, where this number is

The indicator is shown in block 10 playback. Formula

the invention

A device for detecting a damaged section of the power grid in case of a single-phase earth fault, containing a serially connected start-up unit, a switching and coding unit, a matching transformer, a high harmonic filter and a rectifier connected in series to a maximum level fixing unit

 neither, the memory unit, the information transmission unit and the playback unit, the second output of the switching and coding unit is connected to the second input of the memory unit, characterized in that

that, in order to increase reliability, a series-connected voltage adder and a voltage divider are introduced into it, two diodes whose cathodes are connected to the input of the fixing unit of the maximum voltage level, the input of the voltage adder connected to the output of the rectifier and the anode of the first diode, the output of the voltage divider is connected to an additional

the input of the switching and coding unit, the third output of which is connected to the anode of the second diode.

Claims (1)

Claim A device for determining a damaged section of the power supply network during a single-phase earth fault, comprising a start-up unit, a switching and coding unit, a matching transformer, a high-harmonic filter and a rectifier, a series-connected unit for fixing the maximum voltage level, a memory unit, an information transfer unit and a playback unit, the second output of the switching and coding unit is connected to the second input of the memory unit, characterized in that, in order to increase reliability, they are introduced into it after the voltage adder and the voltage divider are connected in series, two diodes, the cathodes of which are connected to the input of the maximum voltage level fixation unit, the input of the voltage adder being connected to the output of the rectifier and the anode of the first diode, the output of the voltage divider is connected to an additional 3Q input of the switching and coding unit, the third the output of which is connected to the anode of the second diode.