RU94077U1 - DEVICE FOR DETECTING THREE PHASE NETWORKS WITH PHASE WIRE INTERIOR - Google Patents

Abstract

 A device for detecting networks with phase-wire breaks, comprising a negative sequence voltage filter, the outputs of which are connected to the signaling organ via a threshold organ, characterized in that a zero-sequence voltage filter connected to the phase wires is additionally installed, the output of which is connected to the zero wire through the second threshold organ connected by the output to one of the inputs of the logical block "AND", the second input of which is connected to the output of the first threshold organ, and the output is connected to toromu body signaling.

Description

The utility model relates to the field of electrical engineering, in particular relay protection and can be used to detect networks with open phase wires.

A device for determining the breakage of insulated wires of overhead lines with a voltage of over 1000 V when they are located on the supports of a contact AC network [1].

This device contains a three-phase supply transformer, the secondary high-voltage winding of which through the switching device is connected to the air-insulated wires of the high-voltage line, at the beginning and end of which transformers are connected, the secondary windings of which are connected in a triangle, and the primary windings connected to the star, the zero points of which through the active capacitive filters are connected to artificial ground electrodes, a threshold element of time, a threshold element of voltage, a logic block “AND”.

When the phase wire is broken, the potential of the zero point of the active-capacitive filter at the end of the line becomes non-zero, therefore, a voltage appears between the zero points of the filters of the beginning and end of the line. Moreover, if the voltage value is greater than the value set by the threshold organ, then the signal will be fed to the input of the threshold time element and one of the inputs of the “AND” block. After the threshold element of time is triggered, the signal will be fed to both inputs of the “And” block, from the output of which a signal will be sent to the switching device to disconnect the line.

The main disadvantages of this device are: the need to use two additional transformers; the inability to distinguish between a phase wire break in a 0.38 kV supply network and a phase wire break in a 10 kV supply network; the need to use additional active-capacitive filters for each connected connection.

The closest in technical essence to the proposed utility model is a negative sequence voltage filter to protect consumers from out-of-phase operation. The filter inputs are connected to the phase conductors of the power line, and the outputs are connected to the signaling organ via a threshold organ [2]. The device is connected to the phase wires on the low voltage side of the transformer 10 / 0.4 kV.

This device has such disadvantages as: the inability to distinguish between a phase wire break in a 0.4 kV supply network and a phase wire break in a 10 kV supply network, which increases the time to search for damage.

The utility model is aimed at reducing the time to find the breakage of the phase wires of three-phase power lines due to the difference in the qualitative characteristics of the voltage during the breakage of phase wires in series-connected three-phase networks of different voltage classes.

The technical problem is realized in that the device for detecting networks with phase-wire breaks contains a negative sequence voltage filter connected to the phase wires, the outputs of which are connected to the signaling organ via a threshold organ, according to the proposed utility model, a zero-sequence voltage filter connected to the phase wires is additionally installed, output which is connected to the neutral wire through the second threshold organ connected to one of the inputs of the logical block "And", the second input for which it is connected to the first threshold organ, and the output is connected to the second alarm organ.

Installation of additional elements according to the proposed utility model allows to solve the technical problem due to the fact that the zero-sequence voltage filter reacts to wire breakage only in the network of the voltage class in which it is installed. Therefore, comparing the presence of signals from two filters, it is possible to determine in which network a break occurred and, due to this, accelerate its localization by sending a repair team to the network area with damage.

Figure 1 shows a General diagram of a device for detecting networks with broken phase wires.

Figure 2 shows the connection diagram of the device to the protected line.

Figures 1 and 2 show a device containing a negative sequence voltage filter (FNOP) - 1, connected to three phase wires, and its outputs are connected to a threshold organ - 2. A zero sequence voltage filter (FNNP) is connected to the same phase wires - 3, which is connected by an output to the neutral conductor through the threshold organ - 4. The outputs of the threshold organs - 2 and - 4 are connected to the inputs of the logic block “I”, the output of which is connected to the signaling organ - 6, and the output of the threshold organ - 2 is also connected and to the body of the alarm AI - 7.

A device for detecting networks with broken phase wires works as follows.

Consider the principle of operation of the device for detecting networks with broken phase wires in the initial state, when all the wires of the power line on the high and low voltage side of the transformer - 8 10 / 0.4 kV are not damaged and the zero and negative sequence filters are connected to a three-phase network. The connection diagram of the device in this mode is presented in figure 2.

As you know, the power supply of three-phase consumers of electric energy is carried out by a symmetrical voltage system in which the components of the reverse and zero sequence are equal to zero. Therefore, when connected to a network with such a system of filter voltages of the reverse sequence, the potential difference between the outputs of the filters will be zero. The same potential difference will be between the output of the zero sequence filter and the neutral conductor.

However, when a phase wire breaks, the symmetrical voltage system ceases to be such. Since the voltage system is asymmetrical, therefore, the network will contain components of the zero and negative sequence, which can be fixed by filters. A voltage will appear between the outputs of the voltage filter of the negative sequence - 1 and, - if its value is greater than the voltage of the threshold organ - 2, then the output of the threshold organ - 2 will receive a signal that will be fed to the logical unit "I" - 5 and the alarm organ - 7, which will cause it to trigger. Between the output of the zero-sequence voltage filter - 3 and the neutral conductor there will also be voltage, and if its value is greater than the threshold voltage of the threshold organ - 4, then a signal will appear at the output of the threshold organ - 4, which will be fed to the logical unit “I” - 5 A signal is supplied to both inputs of the logical block “I” - 5, therefore, from its output the signal will be sent to the signaling organ - 6. Thus, when a phase wire breaks in the 0.4 kV network, both signaling organs will work.

Consider the operation of the device with a broken phase wire in a 10 kV network. In this case, the network will contain symmetrical voltage components of only the forward and reverse sequences, because zero sequence voltages are not transformed to the low voltage side of the transformer. Therefore, the potential difference will occur only between the outputs of the negative sequence voltage filter - 1. This potential difference will be applied to the threshold organ - 2, which will trigger it, therefore, the signal will be fed to one of the inputs of the logic block “I” - 5 and the alarm organ - 7. Thus, in this mode, only one alarm organ will work, which will distinguish it from a broken phase wire in the 0.4 kV network.

This device allows you to determine the network with a broken phase wire by the number of triggered alarm organs.

Information sources

1. Pat. on PM RU 85410 U1 of the Russian Federation, IPC V60M 3/00. Device for determining the breakage of insulated wires of overhead lines with voltages exceeding 1000 V when they are located on the supports of a contact AC network [Text] / A.B.Kosarev, DGKuznetsov SVLoginov (RF) applicant and patent holder GOU VPO Moscow State University of Railway Engineering. - No. 2009108971/22; declared 03/13/2009

2. Fedoseev A.M. Relay protection of electric power systems. Relay protection of networks: Textbook. manual for universities.- M .: Energoatomizdat, 1984. - p. 355.

Claims (1)

A device for detecting networks with phase-wire breaks, comprising a negative sequence voltage filter, the outputs of which are connected to the signaling organ via a threshold organ, characterized in that a zero-sequence voltage filter connected to the phase wires is additionally installed, the output of which is connected to the zero wire through the second threshold organ connected by the output to one of the inputs of the logical block "AND", the second input of which is connected to the output of the first threshold organ, and the output is connected to toromu body signaling.