SU1494107A1 - Device for prevention of converter activation in case of a short-circuit in line of power network - Google Patents

Abstract

The invention relates to electrical engineering, in particular, to the field of electrical equipment protection, and can be used at electric transport converting substations. The purpose of the device is to determine the state of the line before turning on the thyristor converter or the linear switch on the line. The purpose of the invention is to improve the accuracy and reliability of the device. The device is based on a thyristor conversion unit, in which the thyristors are used as a regulator of a gradually increasing test voltage. The installed current and voltage sensors, together with the control system, determine the state of the line and, depending on its state, prohibit or enable the converter or the linear switching device to work on the line. 4 il.

Description

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The invention relates to electrical engineering and can be used, for example, in electric vehicle converting substations.

The purpose of the invention is to improve the accuracy and reliability of the device.

On "1ig. 1 is a functional diagram of the device for preventing a short-circuit from being turned on in a line of a traction network; Fig. 2 is a functional block diagram of a pulse-phase control unit; on () ig.Z and A - time diagrams), which explain the principle of operation of the device, where Ua, U.,

U (v - voltages of phases A, respectively

in, with, and. and, oh and „, and ,,,, and ,,. U23 voltage, respectively, on elements 3-5, 10-14, 18, 11, 33.

The device contains a thyristor converter connected to a three-phase A, B, C alternating current circuit. A switching unit 2, made in the form of a disconnector or a linear circuit breaker, connects the output of the converter to the supply network with a load 3. The output of the converter is connected to sensor 4

voltage, and at the input of bodies connected sensor 5

transform

current. Tirisgo {converter converter controls the system 6 of the pulse-phase control with the power source 7. The device also contains a comparator 8 with a setpoint equal to the value of the short circuit current in the traction network when the converter is in operation: unit 9 of pulse-phase control, threshold element 10 that converts the value of the line test current into square impulses, units 11 and 12 of forming the impulse along the front and the falling edge of the signal coming from the output of the threshold element 10, 15 of block 9 appears to be pulses of the control- integrators 13 and 14 values of the current of the thyristors of the converter, voltage applied with a reset, the comparator 15, the setpoint determines the value of the maximum possible test voltage at which the proposed device is turned off and the converter is turned on to work on the line after turning on the RS flip-flop 16, which includes the sysgem 1 unit of the pulse-phase control of the thyristor converter, the comparator 17 comparing the integrated current values and the voltages and triggered when exceeded 25 are the values of the test current. Moreover, the test current due to the presence of the inductive component of the line lags behind the test voltage at an angle Cf

current value, above prointeg-30 (figure 4). Test Current Values

the test value of the test voltage, the elements of the IS-NOT 18, OR 19, 20, block 21 of the input signal delay and the switch 22, RS-flip-flop 23, including the key element 24 in the presence of logical 1 on the inverting output of the trigger, 1 из from capacitor 26 and discharge resistance 27.

Pulse-phase control unit 9 can be performed, for example, according to the scheme shown in Fig. 2, where unit 9 is soda (matching transformer 28, diode 29, synchronizing unit 30, sawtooth generator 31, the comparator 32 voltage on cumulative element 25, pulse shaper 33 on the leading edge of the input signal, output elements 34, 35, controlling two thyristors of converter I.

The device works in the same way.

In the input state, converter 1 is turned off, switching unit 2 is turned on, and key element 24 is closed. Accumulative element 25 zar

until the voltage of gshtani + u. Before switching on the converter, the traction network is checked for the presence of a short line call. To this end, the MM) 1 is the switch 22, which switches the trigger 23, which turns off the key element 24.

At the same time, the voltage on the capacitor and 26 begins to decrease due to the discharge of the capacitor 26 to the resistance 27. When decreasing, to the maximum value of the sawtooth voltage of the generator 31 at the output

than a decrease in U causes a change in the angle of regulation of the thyristors of the converter from c1 to off, (figure 3).

In this case, each adjustment angle corresponds to the process of testing the line for the presence of a short one for 411 cloths. In the course of testing the line network, it is probed by voltage pulses

which correspond to the test current values. Moreover, the test current due to the presence of the inductive component of the line lags behind the test voltage at an angle Cf

and the voltages through the sensors 4, 5 are supplied to the integrators 13, 14, the first current pulse being converted by the threshold element 10 into a rectangular pulse, on the front of which the impulse forming unit 11 forms an initial reset of the integrators by the input signal. The output of the comparator 17 to the output of the NAND 18 element is synchronized with the time Wt, (FIG. 4), which, together with the integrators 13 and 14 and the voltage sensor 4, increases the noise immunity and accuracy of the device.

In the event of a short circuit in the line t of the new network, the voltage at the output of the integrator 13 becomes greater.

than the output voltage

integrator 14, which leads to dropping the comparator 17 and passing its output signal through the AND-NOT 18, OR 19 element to the R-Trigger 23, which switches and turns on the key element 24, while the voltage on the capacitor rises to + U, which leads to the disappearance of the thyristor control pulse

514

and disconnect the converter. After an input signal delay time determined by delay unit 21, trigger 23 through OR element 20 is re-thrown and turns off key element 24, and again the voltage U "decreases, which leads to automatic repetition of the line from the beginning, from the angle a /, . And

with a short zagkaniya in the line, this process will automatically repeat, starting with a test voltage equal to zero, up to a voltage at which a short circuit will be detected again, if the short circuit in the traction network disappears, the voltage at the integrator output 13 will always be less than the voltage at the output of the integrator. 14 In this case, the test voltage will increase with each period. At a voltage equal to the setpoint of the comparator 15, which determines the maximum value of the test voltage, the output signal of the comparator 15 flips the trigger 16, which through the OR 19 element, the trigger 23 turns on the key element 24, which leads to the disconnection of the 9-phase-pulse control and switching on of the systems 6 of the pulse-phase control, providing switching on and operation of the thyristor converter to the line of the traction network. If, during normal operation of converter 1 to load 3, a short number 1 at the output of converter I occurs, this will lead to an increase in the current at the converter input, triggering the comparator 8, which flips trigger 16, turning off pulse-phase control system 6, which includes a block 9 of pulse-phase control through the elements OR 20, trigger 23 and key element 24,

Thus, each time before switching on the thyristor converter on the line, a Tafffle line test will occur and in the absence of a short link in the line of the traction network, the thyristor converter will automatically turn on to work on the line,

Claims (1)

Invention Formula A device to prevent the converter from being turned on for a short time. 76 ) lkanit r line gg opsi network equipped with systems. - impulse-phase control with and CTOMIIUKOM nutrition, soda) g. 1: c (: e commutative element, predtcIa ish.guy dh hklyucheni at the output of the pr (l) Gfa :(.) Is the gel, and the current sensor, about that, In order to improve the accuracy and reliability of the PGA, and a voltage sensor, three comparators, two integrators with a reset, a threshold element, blocks of forcing of a pulse along the front panel and aimHeNty of the front of the input signal, two elements OR, a block of the input of the 11th link, two RS flip-flop, pulse-phase control unit, accumulative element, NAND element, switch and key element, with the sensor being It is not designed to turn on the converter output, the current sensor is to turn on the converter input and the output is connected to the input of the first comparator, the input of the first integrator with a reset and the input of the threshold element, the output of which is connected to the inputs of the forcing of pulses ahead of and forward. the front of the input signal, the output of the voltage sensor is connected to the input of the second KOMnapaTLipa and the input of the second integrator with a reset, the output of the pulse shaping unit on the leading edge of the input signal is connected to the inputs resetting the first and second integrators, the outputs of which are connected to the inputs of the third comparator, the inputs of the NAND element are connected to the outputs of the third comparator and the output of the pulse shaping unit on the falling edge of the input signal, and the output of the NAND element is connected to the first input of the first OR element and the input the input delay unit whose output is connected to the first input of the second OR element, the second input of which is connected to the switch, and the third input to the output of the first comparator and the R input of the first trigger S whose input from single with the output of the second comparator, the inverting output of the first trigger is designed to be connected to the pulse-phase control system, and the non-inverting output is connected to the second input of the first element, the output of which is connected to the R input of the second trigger, S-BSHED which is connected to the output of the second element OR the inverting output of the second trigger is connected to the control input of the key element, the input of which is intended to be connected to the power source of the pulsed-phase unit 25 control, and the output is connected to the storage element and the control input of the pulse-phase control unit, the output of which is intended to connect to the control input of the converter, fig FIG. 2