SU1488914A2 - Device for monitoring state of converter thyristor - Google Patents

Description

The invention relates to electrical engineering. The purpose of the invention is to expand the functionality of the device for monitoring the status of the thyristor of the converter by identifying the failure type of control system failure. The duration of the zero-level signals at the output of the shapers of time intervals 11 and 12 when the inverter is in good condition exceeds the duration of the conductive and nonconducting states of the thyristors of the converter, respectively, by the delay time of the element 10, and the output of the And 13 element forms a logical zero. With the disappearance of the control pulses, the formers 11 and 12 do not start and at their outputs there are signals of a logical unit. Since the input of the trigger at this point is also one, from the output of the element I 13 to the input of the device receives a signal corresponding to a fault in the control system. 2 Il.

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„„ 1488914 А 2

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The invention relates to electrical engineering, can be used to monitor the state of thyristors and protection of converters and is $

improvement of the device on the main av.sv, № 1224896.

The purpose of the invention is to expand the functional capabilities of the device for monitoring the TYRIST-CONDITION STATE of the converter by identifying a failure of the control system type.

FIG. 1 shows a diagram of a converter with a device for control; 15 For the state of the thyristor; in fig. 2 timing diagrams explaining the operation of the device.

The device for monitoring the thyristor status of the converter contains 20 first -1 and second 2 junction elements, the inputs of which are respectively connected to the control transitions of the controlled thyristor 3 and thyristor 4 of the next in order switching phase of this same group of valves, sensor 5 of the controlled thyristor, the output of which through the driver 6 pulses connected to the first input of the trigger 7, the second input of the trigger 7 is connected to the output of the second element 2 junction, the element BAN 8, the first (inverse) input of which is connected to the output the dy of the junction element 1, and the second (direct) - to the output of the current sensor 5, the AND 9 element, the first input of which is connected to the inverse output of the trigger 7, and the second through the delay element 10 to the output of the first junction 1, the driver 11 pulses of a given duration whose input is connected to the control transition of the controlled thyristor 3, shaper 12 pulses of a given duration, the input of which is connected to the control transition of the thyristor 4 following the order of the phase of the same group of gates, element 13, the first input of which It is connected to the inverse output of the trigger 7, the second input to the inverse output of the former 11, and the third input to the inverse output of the former 12.

The operation of the proposed device is illustrated by the voltage diagrams shown in FIG. 2, where the following notation is taken: and,

Π ϊ. - control pulses, 4

thyristors 3 and 4, respectively; and _s , and ₊ - signals at the inputs of the first and second elements 1 and 2 junction, respectively; and y is the signal at the output of the current sensor; and the output signal of the driver 6 pulses; and ₇ is the signal at the inverse output of the trigger 7; and _in - the signal at the output of the element BAN 8; id- signal at the output of the element And 9; and ₁₀ ~ signal at the output of the delay element 10; and - the signal at the inverse output of the driver 11 time intervals; and the signal at the inverse output of the driver 12 time intervals; and _1E - the signal at the output of the logical element And 13; "1" signal at the level of logical units; "0" - signal at the level of logical zero; V - current time.

In the normal mode of operation of the thyristor converter, diagrams. we are the stresses for which are shown in FIG. 2a, with a continuous load current after the supply of a control pulse to the controlled thyristor 3, the load current flows through the latter. At the output of the discharge element 1, a signal is set at the level of a logical unit, due to a voltage drop at the control transition of the thyristor 3. At the output of the junction element 2, the signal at the level of logic zero is kept during the conducting state of the monitored thyristor 3. When the load current flows through the controlled thyristor 3, the output of the current sensor 5 sets a signal corresponding to the level of the logical unit, under the action of which a signal appears at the output of the pulse shaper 6, which sets the trigger 7 to the position corresponding to the logic zero signal on its inverse output

Thus, the first (inverse) and second (direct) inputs of the BAN 8 element receive signals at the level of a logical unit, which provides at its output a signal at the level of logical zero. At the first input element And 9 there is a signal at the level of logical zero, which provides a logical zero at its output. In normal operation of the thyristor 3, the signal at the level of the logical unit is fed to the second input ele5

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ment And 9 after the inverse output of the trigger 7 is set to a signal at the level of logic zero, which is provided by connecting the output of the junction element 1 to the second input of the element And 9 through the element

10 delays. The absence of signals at the level of the logical unit at the outputs of the And 9 and BAN 8 elements indicates that there are no faults of the “breakdown” type and the “break” type in the controlled thyristor.

When the thyristor converter is operating in a discontinuous load current mode, after a current is reduced through controlled thyristor 3 to zero, the output of the BAN 8 element sets the signal at the logic zero level, which is due to the zero signal level at the output of the current sensor 5, and hence at the direct input of the BAN element 8, for this case, the state of the element BANGE 8 does not depend on the output signal of the junction element 1.

During normal operation of the thyristor converter, a control pulse applied to the controlled thyristor 3 starts the driver

11 at its inverse output a signal appears at the level of a logical zero, whose duration is ν _? equals

where w is the number of pulsations rectified by one valve group of voltages;

V - the delay time of the high-speed signal of the element

10 delay

Control pulse applied

On the thyristor 4 of the next in order phase switching of the same group of valves, the driver 12 starts and at its inverse output a signal appears at the level of a logical zero, the duration of which V _ί2 is equal to

^ν η + V,

(T = 21? ·

2ίι

tp

12

that

where t = 21? - the repetition period of control pulses applied to each of the thyristors of the converter;

(21? - ^t A?) “The duration of the nonconducting state of each

from thyristor circuit,

five

The duration of the signals at the level of logic zero on the inverted outputs of the formers 11 and 12, respectively, exceed the duration of the conductive and nonconducting states of the converter thyristors by the value V, completely eliminating the appearance of a signal at the level of the logical unit at the output of the And 13 element,

15 i.e., the possibility of the emergence of a false signal of the “control system failure” type during normal operation of the thyristor converter is eliminated.

2o At the time of receipt of the control pulse to the controlled thyristor 3 at the inverse output of the driver 12 there is a signal at the level of logic zero, which keeps its

25 value during the time interval equal to V. At the inverse output of driver 11, a signal is generated at the level of logical zero, which provides a signal at the level of logical zero at the output of AND 13, Similarly, at the moment the control pulse arrives at thyristor 4 following the order of switching the phase of the same group of valves on the inverse output of the driver 11 has a signal at the level of logic zero, which still retains its value

for a time interval equal to

40 ν ^. In this case, the inverse output of the driver 12 generates a signal at the level of logic zero, which provides a signal at the level of logic zero at the output of the element 13. So

4 ₅ in the normal operation of the thyristor converter at the output of the element And 13 there is a signal at the level of logic zero, which indicates the absence of a malfunction of the type "control system failure

NIA.

The operation of the proposed device in the event of a breakdown type failure is illustrated by voltage diagrams 55 in FIG. 26. If breakdown

controlled thyristor 3 has

place on the interval of its conductive

states then at first inverse

the entry element BAN 8 enters

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the signal at the logic zero level, due to the zero voltage drop at the control transition of the monitored thyristor 3. The second input of the BAN 8 element receives a signal at the level of the logical unit caused by the flow of direct current through the controlled thyristor 3. · Therefore, the signal at the output of the BAN 8 element appears logical unit.

If the controlled thyristor 3 breaks through with the reverse voltage on the interval of its non-conducting state when the thyristor of the other phase of the same valve group is operating, then the first inverse input of the BANNER element goes to the logic zero level, which is caused by the zero voltage drop on the control transition of the controlled thyristor 3, and to the second the input of the element BANGE 8 receives a signal at the level of a logical unit, caused by the flow of reverse current through the controlled thyristor 3. The presence of signals of specified levels at the inputs of the element This BAN 8 leads to the formation of a signal at the level of the logical unit at its output. Thus, any case of breakdown of the controlled thyristor 3 leads to the appearance of a signal at the level of the logical unit at the output of the BAN 8 element, which indicates the occurrence of a breakdown type.

The operation of the device in the event of a “break” type fault is illustrated by the voltage diagrams in FIG. 2c. When a fault appears in the controlled thyristor 3 when the control pulse is applied to it, the thyristor does not open and the current will not flow through it. In turn, this leads to the absence of a signal at the level of the logical unit at the output of current sensor 5, as a result of which the pulse shaper 6 does not set the trigger · 7 to the state corresponding to the signal at the logic zero level at its inverse output. Therefore, the inverse output of the trigger 7 maintains a signal at the level of the logical unit set by the output signal of the decoupling element 2 when a control pulse is applied to the thyristor 4. After a time Vy from the moment of supplying the control pulse to the controlled thyristor 3, the output signal of the delay element 10 is generated the level of the logical unit, which leads to the appearance of a signal at the level of the logical unit at the output of the element And 9, indicating the occurrence of a fault type "open".

The operation of the proposed device in the event of a malfunction of the control system (CS), due to the absence of a control pulse applied to the controlled thyristor 3 at the required time, determined by the control angle, is illustrated by the voltage diagrams in FIG. 2g. If a controlled pulse does not arrive at the controlled thyristor 3 at the required time, it will not open and no current will flow through it. Therefore, the inverse output of the trigger 7, as in the case of a fault of the type “break”, maintains a signal at the level of a logical unit. Since there is no control pulse, the driver 11 does not start and at its inverse output the signal at the level of the logic unit is stored. After a time from the moment when the control pulse to the controlled thyristor 3 was to arrive, a signal at the level of a logical unit is established at the inverse output of the shaper 12. The presence of signals at the level of the logical unit at the three inputs of the element I 13 ensures the appearance of a signal at the level of the logical unit at its output, which indicates the occurrence of a fault like "failure of the control system".

The proposed device performs the functions of monitoring the state of one thyristor and the corresponding control channel, and also allows you to identify faults of the type "breakdown", "break" and "failure of SU" and can be used when building protection systems and diagnosing thyristor converters with any number of phases. devices for the entire converter is determined by the number of its shoulders. The isolation element 2 used in the proposed device, when monitoring the thyristor 4, performs the same functions as the isolation element 1 during contact

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the role of the thyristor 3, and the decoupling element 1 when controlling the thyristor of the previous phase of the same group of valves performs the same role as the isolating element 2 when controlling the thyristor 3.

Claims (1)

Claim A device for monitoring the status of the thyristor converter on the author, St. No. 1224896, characterized in that, with the aim of expanding functionality by identifying faults of the "control system failure" type, a three-input element And and two pulse generators of a given duration, the inputs of which are connected respectively to the inputs of the first and second decoupling elements, are entered, the outputs Ιθ are united with the first and second inputs of the three-input element And, the third the input of which is connected to the trigger output, and the output is used as one of the device outputs.