RU2397502C1 - Control device of transient and sustained short circuit in alternating current contact network - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: device includes residual voltage transformer connected to contact network with sectioning point. Switches connect contact network and "two wires-rail" line to buses of traction substation. Crank relay with coil and with contact closing with delay and time relay are connected to power supply through in-series connected closing contacts of repeating relays of the switch protections. Filter decreases the level of higher harmonic components in the curve of residual voltage supplied to input of low-frequency filter (LFF) with range of transmission of 0…48 Hz and to input of comparing unit through time relay contact closing with delay. Outputs of LFF and comparing unit are connected to input of amplifier the output of which is connected to output relay. Additional pushbutton switches the device to the search mode of sustained short circuit.

EFFECT: enlarging functional capabilities of the device owing to providing the search of damage by using induced voltage effect.

1 dwg

Description

The invention relates to a system for automating the power supply of electric and railways, and in particular to short-circuit monitoring devices in a contact alternating current network.

A known device for monitoring a short circuit in a contact AC network [1 - prototype], containing an output relay with a make contact, a contact network and a longitudinal power supply line of 27.5 kV "Two wires-rail (DPR)" connected through switches to the buses of traction substations , post sectioning the contact network, a residual voltage transformer connected to one of the switches of the contact network, a start relay, in which the first input of the coil is connected through series-connected closing contacts of the relay - repeaters of protection to the "minus" of the power source, and the second input directly to the "plus" of the power source, the filter of the highest harmonic components of the residual voltage, the input of which is connected to the secondary winding of the residual voltage transformer through the start-up relay with a delay contact, low-pass filter (low-pass filter) ) with a transmission region of 0-40 Hz and an amplifier, the LPF input being connected to the filter output for filtering the higher harmonic components of the residual voltage, and the LPF output to the amplifier input, while the output the amplifier is connected to the input of the output relay, the comparator, the time relay and the make contact of the relay of the off-state relay of the contact circuit breaker to which the residual voltage transformer is connected, and the circuit from the series-connected coils of the time relay and the make contact of the relay of the repeater of the off-state switch is connected in parallel the start relay coil, and the comparator input is connected to the filter output to filter higher onicheskih components and the output of the comparator is connected to the input of the amplifier.

Thus, the specified device immediately after an emergency shutdown for up to 0.5 ... 1.5 seconds determines: short circuit (short circuit) passing or stable. With a passing short circuit, a high-speed automatic restart (BAPV) of the emergency-off circuit breaker, to which the residual voltage transformer is connected, is performed.

(Explanations. Passing short circuit after disconnecting the corresponding feeders of the contact network, that is, in the disconnected contact network, the short circuit is self-destructing (for example, when the isolator of the contact network is closed during a thunderstorm). With a stable short circuit - it is not eliminated in the disconnected contact network.)

The disadvantage of this device is that it works and determines a passing or stable fault only immediately after an emergency shutdown of the circuit breaker for up to 0.5 ... 1.5 sec. If the device determines that the fault is stable, then a search is made for a place of a stable fault and then repair work is carried out to eliminate the fault. The specified device cannot detect and control the absence of a stable fault during the search and after the elimination of fault.

Known devices for the search for stable faults using the induced voltage effect [2-5]. However, they do not determine the passing short circuit in the shortest time (for example, in 0.5 ... 1.5 sec, as indicated above) after an emergency shutdown of the circuit breaker, and therefore with their help there is no way to perform an automatic overvoltage.

The aim of the present invention is to expand the functionality of the device of the prototype (according to the application [1]). In addition to [1], in case of a stable short circuit during the search for a short circuit place and after carrying out repair work to eliminate a short circuit, the device must determine and control the absence of short circuit in a disconnected contact network using the induced voltage effect.

This goal is achieved by the fact that in a device containing an output relay with a make contact, a contact network and a longitudinal power supply line “Two wires-rail (DPR)” connected through switches to the buses of traction substations, a section of the contact network, a residual voltage transformer connected to one of the switches of the contact network, the start relay, in which the first input of the coil is connected through series-connected closing contacts of the protection relay repeaters to the “minus” of the power source, and the second input is directly to the “plus” of the power source, the filter of the highest harmonic components of the residual voltage, the input of which is connected to the secondary winding of the residual voltage transformer through the start-up relay with a delay contact, a low-pass filter (LPF) with a transmission range of 0-40 Hz and an amplifier moreover, the input of the low-pass filter is connected to the output of the filter to filter the higher harmonic components of the residual voltage, and the output of the low-pass filter is connected to the input of the amplifier, while the output of the amplifier is connected to the input of the output relay, com the arator, the time relay and the closing contact of the relay of the off-state relay of the contact circuit breaker to which the residual voltage transformer is connected, the circuit of the time relay coils and the closing contact of the relay of the repeater of the off-state switch being connected in parallel to the start relay coil, and the comparator input through the time relay contact closing with deceleration is connected to the filter output for filtering higher harmonic and the comparator output is connected to the input the amplifier, the output of the amplifier is connected to the input of the output relay, the comparator, the time relay and the make contact of the relay of the off-state relay of the contact circuit breaker to which the residual voltage transformer is connected, and the circuit is made up of series-connected coils of the time relay and the make contact of the relay-repeater of the disconnected state of the switch it is connected in parallel to the coil of the start relay, and the comparator input is connected to the filter output for the filter through the contact closing with the deceleration time relay of the higher harmonic components and the comparator output is connected to the amplifier input, a circuit is introduced with an intermediate relay coil with three contacts connected in series and a stable short circuit control button, connected to the “plus” or “minus” of the power source, and the first closing contact of the intermediate relay shunts connected closing contacts of the relay-repeaters of protection, the first conclusions of the second making and third opening contacts of the intermediate relay through the closing contact the act of the output relay is connected to the “plus” of the power source, and the second terminal of the second make contact is connected to the signal circuit of the stable short circuit and the second output of the third make contact is connected to the switch circuit of the contact network switch, which is connected to the residual voltage transformer.

This embodiment of the device, in which a circuit is introduced with the intermediate relay coil connected in series with three contacts and a stable short circuit control button, is connected to the “plus” or “minus” of the power supply, and the first closing contact of the intermediate relay shunts the series-connected closing contacts of the relay-repeaters protections, the first conclusions of the second make and third make contacts of the intermediate relay through the make contact of the output relay are connected to the "plus" of the source Itani, and the second terminal of the second switching contact is connected to a circuit signaling sustained short circuit and a second terminal of the third break contact connected to a circuit switching network of the switch contact which is connected to the transformer residual stress, it allows to expand the functionality of the device, namely:

- the device determines the passing short circuit in a minimum time (up to 0.3 ... 0.5 sec) after an emergency shutdown of the circuit breaker and then gives a command to turn on this circuit breaker,

- the device determines a stable short circuit and then gives a ban on the inclusion of an emergency-off circuit breaker,

- newly introduced function: in the process of finding a place for a stable fault and after repair work, the device determines and monitors the absence (elimination) of fault in a disconnected contact network.

The drawing shows a diagram of a device that contains a contact network 1 with a sectioning station 2, connected via switches 3, 4, 5, 6 to the buses 7 and 8 of the traction substations, the longitudinal power supply line "Two wires-rail (DPR)" 9, connected through a switch 10 to the bus 7 of the traction substation, a residual voltage transformer 11 connected to the switch 3, a start relay 12 with a coil 13 and a make contact 14, connected to the power supply "+" and "-" through the sequentially connected make contacts 15 and 16 of the relay repeaters circuit breaker protection 3. Filter 17 reduces the level of higher harmonic components in the curve of the residual voltage supplied to the input of the filter 18 low frequency low-pass filter with a transmission zone of 0 ... 48 Hz. The output of the low-pass filter 18 is connected to the input of the amplifier 19, which is connected to the output relay 20 with the closing contact 30. Parallel to the coil 13 of the start relay 12, the coil 21 of the time relay and the closing contact 22 of the relay of the repeater of the off position of the switch 3 are connected. Comparator 23 compares the voltage from the transformer voltage with a given voltage Uo is connected to the output of the filter 18 of the highest harmonic components through contact 24 of the time relay closing with deceleration. An intermediate relay 25 with a coil 26 and three contacts: closing 27 and 28 and opening 29, is connected to the “+” - “-” power supply via the control button for a stable short circuit. The device operates as follows.

In the presence of electric rolling stock and in the case of a passing short circuit, circuit breakers 3, 4, 5, 6 are turned off, it is started from the protection of circuit breaker 3 (contacts 15 and 16 are closed) of the start relay 12, and voltage 14 is applied to the filter 17 from the transformer of residual voltage (residual voltage generated in the contact network by phase-splitter EPS). Further, the low-pass filter 18 determines that the frequency of the residual voltage is lower than 48 Hz and, through the amplifier 19, turns on the output relay 20 with the closing contact 30, which performs a fast automatic switch (BAPV) of the switch 3 through the contact 29 (on).

However, in the same situation, in the absence of ESR on the disconnected section of the contact network, the residual voltage will be zero and then it is not clear whether this is the result of a stable fault or absence of ESR.

In this case, the invention uses the effect of induced voltage from a longitudinal power supply line of 27.5 kV "Two wires-rail (DPR)" [2], located on the supports of the contact network (from the field side). The specified line is intended for power supply of non-traction consumers of relatively small power located along the railway. Therefore, the induced voltage is determined mainly by the electric effect, the induced voltage from the magnetic effect of the DPR according to experimental data is 10 ... 30 times less than from the electric.

According to experimental data, the induced voltage measured by the voltage transformer in different parts of the contact network of the 25 and 2 × 5 kV system is 2.6 ... 7.1 kV (in the absence of a stable short circuit), and in the short circuit on the contact network it did not exceed 80 ... 350 V ( as a result of magnetic influence).

Thus, if after turning off the switches 3, 4, 5, 6, the residual voltage is absent, the device operates as follows.

When the switch 3 is turned off, the contact 22 of the repeater relay of the disconnected state of the switch 3 is closed, the coil 21 of the time relay is connected to the power supply "+" and "-", the time relay is activated and its contact is closed 24. Thus, the voltage from the voltage transformer 11, which in this case, it controls the induced voltage in the contact network from the DPR 9, through pin 14, the filter 17 and pin 24 are supplied to the comparator 23. The comparator must determine: the measured voltage is greater than the specified 80 ... 350 V (with a margin of accepted Uo = 500 V)? If yes, then there is no short circuit. Otherwise, KZ is sustainable.

So, if the voltage U from the voltage transformer 11 is greater than Uo, then a command is sent to the output relay 20 through the amplifier 19 and then the circuit breaker 3 is turned on through contacts 30 and 29.

If U is less than Uo, then this means K3 is stable, and the switch will not turn on.

The setting of the relay 24 for closing the contact 24 must exceed the time to trip the switches 3, 4, 5, 6 from the protection (taking into account their cascade action) and with a margin of 0.8 ... 1 sec.

With a stable short circuit, the search for a short circuit begins. In this case, the section from the feeder with switch 3 remains disconnected until the sectioning station, since we assume that the short circuit is stable in this section, the remaining sections (from other switches 4, 5, 6 and to the sectioning station) are included in the operation. If there is a stable fault in another section, then the search process will not change (it is assumed that residual voltage transformers will be installed on other switches).

The search sequence for the short circuit is as follows.

Press button 31 (the button with retraction, that is, after pressing it remains in the on position), relay 25 activates. Then contact 28 closes, relay 13 trips and relay 22 closes when relay 22 is closed, contacts 14, 24 are closed and the voltage from the residual transformer voltage 11 is supplied to the comparator 23.

At the command of the energy dispatcher, in order, the longitudinal disconnectors of the contact network are disconnected from the sectioning station 2 towards the switch 3, which remains disconnected [2, 3].

If, after disconnecting the next disconnector, the stable short circuit does not disappear, then at the input of the comparator there is zero voltage, terminal 30 remains in the off position and after terminal 27 there is no signaling command. Recall [2, 3] that during a short circuit on the contact network, the electrical component of the induced voltage is zero, and the magnetic component of the induced voltage from the contact network of the adjacent path is “extinguished” by the filter 17.

If after disconnecting the next disconnector, the short circuit disappears, then this means that the short circuit has been found. In this case, the comparator 23 is triggered from the induced voltage, then the output relay 20 closes the contact 30 and through the closed contact 27 a command is sent to the alarm actuation circuit, which indicates the absence of a short circuit.

After eliminating the damage, turn off button 31.

Thus, the final algorithm of the device is as follows.

Stage 1. 1. After the circuit breakers 3, 4, 5, 6 are turned off, the filters 17 and 18 are turned on and, in the presence of residual voltage, the output relay 20 is activated and circuit breaker 3 is turned on according to the BAPV.

2. If there is no residual voltage, then after 0.6 ... 1 second voltage is applied to the comparator 23.

3. If U is greater than Uo, an amplifier 19 is given a command to operate the output relay 20 and then to turn on the switch 3.

2 stage. 4. If U is less than (or equal to) Uo, the command to turn on the switch 3 is not given (since the sign of a stable fault in the contact network is determined). If the command to turn on the circuit breaker is given through BAPV after 0.5 seconds, then in the absence of EPS and passing short-circuit the command to turn on the circuit breaker 3 will be issued a little later - after 0.8 ... 1 sec. But this is not essential - since in this case there is no consumer - EPS in the contact network.

3 stage. 5. After determining a stable short circuit, the button 31 is turned on and the process of searching and eliminating short circuit begins. An alarm indicates the absence of short circuit in the contact network.

6. At the end of the operation, the button 31 is turned off and the normal power circuit is restored.

Information sources

1. Application for invention No. 2008111210. Short-circuit monitoring device in an alternating current contact network (authors German L.A. et al.). Positive decision of March 11, 2009.

2. Patent for invention No. 2339961 dated 03/27/2007. Short circuit monitoring device in the contact network (German L.A. et al.).

3. Patent for utility model No. 77447 of March 26, 2008. Short-circuit monitoring device in the contact AC network (German L.A. et al.).

4. German L.A., German V.L. Diagnostics of emergency situations of the contact AC network of railways. Electronics and electrical equipment of transport. - 2008, No. 3, p. 41-47.

5. German L.A., Demidov S.V., Popov D.S., Yakunin D.V. A simple way to look for damage on a contact AC network. Locomotive. - 2008, No. 4. p. 45 -46.

Claims (1)

Short-circuit monitoring device in the AC contact network, containing an output relay with a make contact, a contact network and a longitudinal power supply line of 27.5 kV “Two wires-rail” connected via traction substation switches to the traction substation buses, section of the contact network, transformer residual voltage connected to one of the switches of the contact network, the start relay, in which the first input of the coil is connected through series-connected closing contacts of the relay-repeater th protection to “-” the power source, and the second input is directly to the “+” power source, the filter of the highest harmonic components of the residual voltage, the input of which is connected to the secondary winding of the residual voltage transformer through the start-up relay with a delay contact, low-pass filter (low-pass filter) ) with a transmission range of 0-40 Hz and an amplifier, the LPF input being connected to the filter output for filtering the higher harmonic components of the residual voltage, and the LPF output to the amplifier input, while the amplifier output is connected n to the input of the output relay, a comparator, a time relay and the make contact of the relay of the off-state relay of the contact circuit breaker to which the residual voltage transformer is connected, the circuit of the time-relay coils and the make-up contact of the relay of the repeater of the disconnected state of the switch being connected in parallel to the relay coil start, and the comparator input is connected to the output of the filter through the contact closing with the deceleration of the time relay to filter the higher harmonic components x, and the output of the comparator is connected to the input of the amplifier, characterized in that a circuit is introduced with the intermediate relay coil with three contacts connected in series and a stable short circuit control button connected to the “+” - “-” power source, the first closing contact of the intermediate relay shunts the serially connected make contacts of the relay-repeaters of protection, the first conclusions of the second make and third make contacts of the intermediate relay through the make contact of the output relay They are connected to the “+” power source, and the second terminal of the second make contact is connected to the stable short circuit alarm circuit, and the second output of the third make contact is connected to the switch circuit of the contact network switch, which is connected to the residual voltage transformer.