SU1756183A2 - Overvoltage protection device for converter of dc traction substation - Google Patents

Abstract

Usage: electrified transport, technical means of direct substations of electric railways of direct current. Summary of the Invention; The device protects the converter transformer and the semiconductor converter rectifier from overvoltage and has a glitter with a current limiting resistor, two storage capacitors with discharge and charging resistors, a diode, a voltage relay, a charging unit, and a gadget controlling and controlling voltage voltage meter, voltage measuring transformer, two measuring diode bridges, two measuring filters, three position switch, high-speed relay and terminals for connecting yucheni meter time intervals. The difference in the device is determined by the presence of a voltage transformer, diode bridges, measuring diodes, a switch and terminals for connecting a time meter to it. It is possible to predict the technical condition of the bit. 1 il. (Ls

Description

The invention relates to the field of electric railways, is designed to protect against overvoltages of high-power semiconductor converters of direct current traction substations, and is an improvement of the device according to the main auth. No. 1570939.

The known device for protection against overvoltage of a converter station of a direct current, contains a radar with a current limiting resistor, the first and second memory capacitors with the first and second charging and discharge resistors, a diode, a charging unit, its control unit voltage unit, the control unit of the arrester, the voltage meter. The current limiting resistor is connected to one of the terminals of the first storage capacitor, the other terminal of which is connected to the output terminal of the protected converter. To the other output of its output is connected through a diode. Their connection point is connected to the second charging resistor. The common pins of the second capacitor and the discharge resistor are connected to the same output of the protected transducer as one of the pins of the output of the charging unit rectifier.

The charging unit is made in the form of a rectifier and included in a step-wise manner a step-down and step-up transformer.

ate about

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with

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tori. The downstream transformer is connected by its primary winding with alternating voltage buses from which the protected converter is powered. The secondary winding of the step-up transformer of the charging unit is connected through its rectifier and the first charging resistor in parallel with the first storage capacitor.

The control unit of the arrester contains a transformer, rectifier and stabilizer on. At least one light indicator and a number of chains made in the form of a relay with a parallel-connected storage capacitor and a series-connected separating diode are connected to the output of the stabilizer. The primary winding of the transformer of this unit is connected to the input of the rectifier of the charging unit.

The voltage control unit is made in the form of series-connected DC and AC resistors, in parallel the opening and closing control buttons and the voltage relay connected in series with it. The resistor circuit of this unit is connected in series to one of the wires connecting the windings of the transformers of the charging unit. The corresponding outputs of the control unit are connected to the output of the control unit rectifier.

The known device does not provide the amount of information, measurement accuracy, which is required for high-quality and reliable diagnostics of the gaps of the protection device.

The purpose of the invention is to improve the quality and reliability of technical diagnostics.

The essence of the invention is as follows. The control unit of the known device is supplemented with a measuring voltage transformer, two measuring diode bridges, two measuring filters, a three position switch and a relay element. The closing contact of the relay element is connected to the terminals for connecting the time interval meter. The presence of these additional elements makes it possible to simplify the technology of technical monitoring of the armature, improve the accuracy of measuring its diagnostic parameters and expand the information content of the monitoring results

In the drawing, the electrical circuit of the device is shown in principle.

The device contains associated with busbars 1 alternating voltage disconnector 2, oil switch 3, converter transformer 4,

a semiconductor converter 5, a fast-acting switch 6, its disconnector 7, and buses 8 of the rectified voltage of the arrester 9 with a spark gap 10, a current-limiting resistor 11 and a diode 12. The device also contains the first storage capacitor 13 with the first discharge resistor 14, the second storage capacitor 15 with the second discharge and charge resistors 16

5 and 17, charging unit 18, voltage regulating unit 19 and control unit 20.

The charging unit 18 consists of rectifying m1 - bodies 21, the first charging resistor 22, increasing 23 and lowering 24 trans0 formatters.

The control unit 19 has a variable 25 and a constant 26 resistors, a voltage relay 27 with buttons 28 and 29 controlling its position.

5 Control unit 20 includes an isolation transformer 30, a rectifier 31, a voltage regulator 32 containing a resistor 33 and a zener diode 34, separation diodes 35 and 36, a relay 37

0 and 38 voltages, respectively, with the storage capacitors 39 and 40, the button 41 controlling the position of the relay 38, the indicator light 42, the relay element 43, the closing contacts of which are connected to

5 terminals 44 for connecting a time meter, voltage measuring transformer 45, measuring diode bridges 46 and 47, measuring filters 48 and 49, switch 50

0 in three positions and a voltmeter 51. Measuring filter 48 (49) includes resistors 52, 53 (55, 56) and capacitor 54 (57).

The drawing does not show the plug to the terminals 44 during the control of the arrester

5 9 time interval meter and relay contact 37, which is involved in the control circuits of switches 3 and 6.

Block 20 has a number of features. Its relay element 43 has a shutdown and release times, less than the quenching time of the accompanying current discharger 9. The transformation ratio of the transformer 45 must be chosen in a certain way taking into account the parameters

5 of the protected converter (its scheme and transformation ratio of the converter transformer), step-down transformer (transformation ratio) of the charging unit and measuring filters (voltage transfer ratio) of the control unit. The need to take these conditions into account when choosing the transformation ratio of the transformer 45 is due to the control of the arrester 9 with a voltmeter 51 measures the sum of the output voltages of the measuring filters 48 (at resistor 53) and 49 (at resistor 56) and the output voltage of each of these filters ditch Therefore, between the voltage of the capacitor 13 (15) and the voltage of the resistor 56 (53) the same proportionality must be maintained. The conditions with which the transformation ratio of the transformer 45 must meet can be expressed by the following equation;

K45

K24 K49 Ksp K4 K48

In this equation, K4, K24, and K45 are the transformation ratios, respectively, of transformers 4, 24, 45; K48, (K4e) voltage transfer ratio of the filter 48 (49), equal to the ratio of the resistance of the resistor 53 (56) to the total resistance of the resistors 52 and 53 (55 and 56); KSp-.g coefficient taking into account the execution of the converter circuit 5. If the converter 5 is made according to a three-phase bridge circuit (two reverse stars with an equalization reactor), then Ksp 1 (Ksp V3).

The parameters of the filter elements 48 and 49 must be such that their output voltage does not have a ripple.

The protection device operation is characterized by two modes: 1 normal operating mode, when the device is in the initial state, when dangerous overvoltages occur in the power circuits of the converter, the converter operates and protects its equipment, and the mode in which the technical condition is monitored surge protection device, while performing its protective functions.

In the first mode, the device operates as follows.

With disconnected disconnectors x 2 and 7, the voltage does not enter the converter power circuit and the protection device.

After switching on the disconnector 2 from busbar 1, a high voltage is applied to the primary winding of the step-down transformer 24 of the charging unit 18. From the secondary winding of this transformer, the reduced voltage goes to the first winding of the step-up transformer 23. The increased voltage of its secondary winding is rectified 21. The rectified voltage charges the capacitor 13 through the resistor 22, which limits its charging current. The voltage of the capacitor 13 has a prolness shown in the diagram. Permanent time

formed by the capacitor 13 and the resistor 14, is significantly longer than the period of the voltage supplying the rectifier 21. Therefore, the voltage of the capacitor 13 does not pulsate.

The AC voltage applied to the input of the rectifier 21 of the charging unit 18 is applied to the primary winding of the transformer 30 of the control unit 20. The secondary voltage of this transformer is rectified by rectifier 31. The rectified voltage is stabilized by stabilizer 32 and then supplied through isolating diode 35 to voltage relay 37 and to capacitor 39. This capacitor charges up to threshold voltage of zener diode 34, relay 37 the voltage is triggered, it changes the position of its contacts (not shown) and thus removes the prohibition to turn on switches 3 and 6.

In this mode, the protection device of the relay 27 of the voltage of the control unit 19 is de-energized, its contacts are open, and a resistor 26 is inserted into the circuit of the charging unit. In the control unit 20, the voltage relay 38 is also de-energized and closes with its contact a circuit of the indicator light 42, which is lit, indicating the presence of a charge in the charging unit 18 and in the control unit 20.

When the switches 3 and 6 are turned off, the spark gap 10 of the spark 9 is connected through the diodes of the converter 5 and diode 12 is applied to the voltage of the capacitor 13. After the switches 3 and 6 are turned on, the capacitor 15 is charged through the diode 1 from the converter 5 to the amplitude of its rectified voltage wives (voltages on tires 8 tons of a govaya substation). The resistor 17 limits the charging current of the capacitor 15 at the first moment after turning on the switches 3 and 6. The voltage of the capacitor 15 has a polarity which is shown in the diagram.

In the presence of voltage across the capacitors 13 and 15, their total voltage is applied to the spark gap 10 of discharge 9. In normal operating modes of the traction substation, the voltage does not exceed the value of the breakdown voltage of the spark gap (discharge) and in the control unit 20 the capacitor 39. is charged and the voltage relay 37 is turned on, the capacitors are charged 13. and 39 and

the on position of the voltage relay37 provides the voltage of the charging unit 18. If for some reason, for example, when the contact is lost, the voltage of the charging unit 18 disappears, the capacitors 13 and 39 begin to discharge, the capacitor 13 is discharged through a resistor 14, the capacitor 39 through the winding of the relay 37 voltage. After stopping the charge of the capacitor 39, the voltage relay 37 due to the energy accumulated in the capacitor 39 continues to be in the on position for some time, then disappears and changes the position of its contacts (not shown). This leads to tripping of switches 3 and 6, which remove the voltage from the power circuit of the converter and remove it from operation. Thus, a mode of operation dangerous for the power equipment of the converter is eliminated, when the voltage on the capacitor 13 is absent and the discharge current 10 can be triggered when an overvoltage occurs that exceeds the permissible level.

In this mode, it is possible: 1 to monitor the voltage that is applied to the spark gap 10 of discharge 9 and the components of this voltage. For this control, the switch GO is alternately set to one of three positions and in each of the H / IX a measurement is taken on a voltmeter scale Y When the switch 50 is in the middle position, the voltmeter 51 meter measures the total voltage of the resistors 53 and 5. which is proportional to the voltage of the game gap 10 of the discharge 9. If the switch 50 is in the upper position and its contact bypasses the resistor 53, the voltmeter 51 shows the voltage of the resistor 56, which characterizes the voltage of the capacitor 13. When the switch 50 is moved to the lower position, its contact bypasses the resistor 55 and the voltmeter 51 measures the voltage of the resistor 53. The magnitude of the measured voltage Identifies the voltage of the capacitor 15.

With the appearance in the power circuits of the overvoltage converter, in which the sum of the amplitude of the rectified voltage of the converter 5 and the voltage of the capacitor 13 exceeds the breakdown voltage of the spark gap 10, the latter breaks through and creates a current circuit between the poles of the rectified voltage of the converter 5. . At the first moment after the breakdown of the spark gap 10, a current flows through the capacitor 13, which discharges to

zero After the capacitor 13 is completely discharged, the current from its circuit passes into the diodes of the rectifier 21 of the charging unit 18. During the flow through these diodes

the current of the capacitor 13 does not vary in time and has a small value equal to the direct voltage drop across the diodes of the two arms of the bridge rectifier 21. The polarity of the voltage of the capacitor 13

0 is opposite to that shown in the drawing.

The magnitude of the current of the arrester 9 is limited by the resistance of its resistor 11. The energy of the overvoltage is dissipated in

5 resistor 11 of bit 9, released in the form of heat. As a result, overvoltage is limited.

After limiting overvoltage, the surge voltage disconnects (extinguishes) the current accompanying it, which flows in its circuit under the action of the rectified voltage of the converter 5. At the time of the discharge of this current, the capacitor 13 has a small value and

5 therefore, only the amplitude value of the rectified voltage of the converter 5, less than the voltage that acts on the spark gap 10 V, is applied to the spark gap 10 of the detector 9.

0 during the normal operation of the converter. the voltage of the charging unit 18 charges the capacitor 13. As this capacitor charges, the voltage of the spark gap 10 increases and reaches the value that occurred before its breakdown when an overvoltage appeared.

During the flow of the discharge voltage 9 through the diodes of the rectifier 2, it forms a short-circuited circuit for the secondary winding of the transformer 23 and its voltage is fully applied to the resistor 22. Therefore, starting from the moment of the occurrence of the discharge current in the diode circuit of the rectifier 21 The voltage is removed from the primary winding of the transformer 30 of the control unit 20. The voltage on this winding corresponds to the moment when the discharge current is quenched by the accompanying current, when the current in the discharge circuit and in the diode circuit

0 flash 21 has stopped. In the time interval when transformer 30 does not receive voltage, capacitor 39 is discharged through the winding of voltage relay 37. The separation diode 35 eliminates the effect

5 shunt circuits (light indicator circuit 42) at the time of the discharge of the capacitor 39. If there is a separation diode 35, the discharge time of this capacitor is determined by its capacitance and parameters (resistance, inductance) of the relay coil 37

voltage, This allows you to control the discharge time of the capacitor 39 and, accordingly, the flow time of the accompanying current in the circuit of the discharge element 9 as follows

If during the flow of the accompanying current in the circuit of the discharger 9, the capacitor 39 does not have time to discharge before the voltage at which the voltage relay 37 drops, then remove the overvoltage and the end of the follower discharger and the inverter will continue to operate. 18 charges the capacitor 39 d.- voltage, corresponding to the capacitor at the og so h / .y protection devices When the jojeoc is quenched with a deactivator accompaniment Dzk. if the current flow time B of the discharge circuit increases, and the voltage of the capacitor 39 decreases, the voltage of the capacitor 39 decreases to such a value that the voltage relay 37 drops and changes the position of its contacts. As a result, switches 3 and 6 remove the voltage from the power circuit of the converter and it is taken out of operation. After that, the accompanying current in the arrester circuit is stopped, the charging unit 18 charges the capacitors 13 and 39 to a voltage that corresponds to the initial state of the protection device, the voltage relay 37 is activated and removes the prohibition to turn on the switches 3 and 6 and, accordingly, on the commissioning of the converter.

The mode in which the technical condition of the arrester is monitored is carried out by performing the following operations.

By turning off the high-speed switch 6, the load-working converter is switched to idle mode. In this mode of operation, the converter its rectified voltage has a stable amplitude, which is remembered by the capacitor 15. Its voltage is applied to the spark gap 10 of the controlled discharge 9.

Then, a time interval meter is connected to the terminals 44 and the switch 50 is placed in the middle position, in which the readings of the voltmeter 51 characterize the voltage value of the spark gap 10 of the monitored bit 9.

Next, pressing the button 41 causes the voltage relay 38 to operate and the light indicator 42 goes out in the control unit 20. As a result, the capacitor 40 is charged to the threshold voltage of the Zener diode 34. The capacitance of the capacitor 40 is chosen such that, if there are ignore diodes 36, eliminating the influence of parallel circuits (stabilizer circuit 32), for the rete 38 voltage, the time delay for falling away corresponds to the characteristic time of the damping of the arrester, for example, the average, maximum or minimum value of this time.

After this: by pressing the button 29, the actuation of the relay 27, which is on duty, changing the position of its contacts, shunts the resistor 26 of the control unit 19. This leads to an increase in the voltage at the output of the rectifier 21, the new capacitor 13 remembers the new the magnitude of this voltage and the voltmeter 51 increase their readings.

After completing the above operations, slowly and smoothly reduce the resistance of the resistor 25 until

0 a spark gap 10 of the monitored spark gap 9 will be struck. At the same time, monitor the voltmeter 51 readings and record them at the moment of time preceding the breakdown of the spark gap 10.

5 These measurement results characterize the magnitude of the breakdown voltage of the spark gap 10 of the controlled discharge element 9.

After the breakdown of the spark gap 10

0, the capacitor 13 is quickly recharged, and the discharge current 21 begins to flow through the diodes of the rectifier 21. As a result, the voltage is removed from the primary winding of the transformer 30 of the control unit 20. The Co5 resistance of the current-limiting resistor 11 and the capacitance of the capacitor 13 are chosen in such a way that its recharging time is significantly less than the time of discharge arcing. In this case, the moment

0 The spark gap gap 10 of 9, which is the beginning of its quenching time, and the moment of voltage relief from control unit 20, used to determine the quenching time, are shifted

5 times are significantly less as compared with the quenching time. Therefore, if the indicated condition is observed, the process of recharging the capacitor 13 does not affect the results of monitoring the quenching time of the 9

0 block 20 control.

Starting from the moment when the discharge current appears in the diode circuit of the rectifier 21, the voltage is removed from the control unit 20, its capacitors 39 and 40 begin

5 discharge through the windings of voltage relays 37 and 38, respectively, voltage relay 27 drops out and its shunt resistor 26 opens its contact.

After a certain time (quenching time) has elapsed, the pattern 9 suppresses the accompanying current. After this, the capacitor 13 is charged by the voltage of the charging unit 18. At the moment when the charge of the capacitor 13 ends, its voltage is less than that which was before the breakdown of the spark gap 10 as a result of the overvoltage simulation, since after the breakdown of the windings transformers 23 and 24, the resistance of resistor 26 was introduced. Therefore, after the termination of the charge of the capacitor 13, the spark gap 10 does not penetrate again. In this way, repeated breakdowns of the spark gap 10, which are undesirable in the monitoring process, are eliminated.

The discharge of capacitors 39 and 40 continues until the voltage on the primary winding of the transformer 30 of the control unit 20 appears. With a constant circuit time, the capacitor 13 is a resistor 22, a much shorter discharge voltage, and the rectifier voltage, rectifier 31, is significantly greater than the threshold voltage of the zener diode 34, the moment the discharge current of the discharge voltage ends. , almost coincides with the moment of occurrence of voltage in control unit 20 and with the moment of termination of discharge of capacitors 39 and 40. After the occurrence of voltage on the windings of transformers 30, capacitors 39 and 40 are charged to the threshold voltage of the zener diode 34

Thus, while complying with the listed requirements for the parameters of the elements of the charging unit 18 and the control unit 20, the quench time and the discharge time of the capacitors 39 and 40 are almost the same value. Therefore, if the quenching time of the discharge exceeds the delay time delay created by the storage capacitor 40 and the voltage relay 38, this relay disappears, remains in this state after the voltage recovery in the control unit 20 and its indicator light 42 turns on. that for a controlled discharge, the quenching time exceeds a certain normalized value. The presence in the device of a relay element 43 and terminals 44 for connecting a time meter to its contacts for the period of monitoring of the bit 9 makes it possible to determine the exact value of the time of the controlled bit to be quenched. This is done as follows.

After a breakdown spark. This gap 10 of the controlled discharger 9 as a result of the imitation of the overvoltage from the control unit 20 is released, the relay element 43 changes the position of its closing contact. This leads to the start of the time interval meter ,, and it produces a countdown of time, starting from the moment of the spark gap 10 of the controlled discharge discharge.

When the time delay 9 suppresses the accompanying current and the control unit 20 is energized again, the relay element 43 again changes its contact position and stops the time counting performed by the time meter.

Thus, the time interval meter starts counting the time at the time of the spark gap 10 of bit 9 and ends this count immediately after stopping the accompanying current in the bit 9 circuit. Therefore, the time interval measured in the described sequence is the value of the quench time controlled by the accompanying bit. current.

If the controlled discharge voltage has an unacceptably long quenching time, then when the spark gap breaks down by simulated overvoltage in the control unit 20, the voltage relay 37 disappears. In this case, as in the similar case of the converter operating mode, switches 3 and 6 are turned off.

When carrying out the described control, the voltage of the capacitor 13 changes only upwards with respect to its initial value in the operating mode. Therefore, the operations necessary for control are accompanied only by a decrease in the setpoint of the operation of the protection device (the difference between the breakdown voltage of the spark gap 10 and 9 and the voltage of the capacitor 13) and cannot cause damage to the converter power equipment.

After completing the monitoring described, voltage relay 38 may be in any position, voltage relay 27 must be turned off. If for some reason, for example, as a result of an erroneous pressing of the button 29, the winding of this relay is under voltage, then by pressing the button 28 the voltage is removed from this winding. The need for this is due to the fact that if you set the trigger point of the protection device when the voltage relay 27 is turned on, then after the first trip of the protection, this relay will disappear and increase the trigger point of the protection device, which is undesirable.

Next, set the triggering value of the protection device in the following sequence.

The switch 50 is shifted to the lower position and the amplitude of the rectified voltage of the bis converter is measured by a voltmeter 51 and taking into account the results of these measurements, the desired response setting of the protection device is found. The need for such an operation is due to the fact that the amplitude of the rectified voltage of the converter 5 depends on the position of the antsapf of the transformer 4 and the step-down transformer (not shown in the diagram) of the traction substation and therefore has an inconstant value

After this, from the previously measured breakdown voltage of the spark gap 10 of the monitored spark 9, the value of the required setting of the protection device is subtracted. The voltage difference thus obtained is the required voltage of the capacitor 13.

This voltage is set as follows. Switching the switch 50 to the upper position, in which the voltmeter 51 controls the voltage of the capacitor 13. By varying the resistance of the Resistor 25 of the Adjustment block, the readings of the voltmeter 51 correspond to the required voltage of the capacitor 13.

Then by turning on the high-speed switch 6, the idle converter is switched to operating mode.

Claims (1)

Claims An overvoltage protection device for a converter substation of a direct current voltage is av. No. 1570939, characterized in that in order to improve the quality of technical diagnostics and increase reliability, the control unit is additionally equipped with a voltage measuring transformer, two measuring diode bridges, two measuring filters, a three position switch, a relay element with response and release times shorter than the quenching time a controlled current discharger discharger, to the closing contacts of which a time interval meter is connected, the voltage measuring transformer being connected to the input the rectifier of the charging unit is connected to the input, and the output to the first measuring diode bridge, the second measuring diode bridge is connected by its input to the secondary winding of a step-down transformer the charging unit, the opposite-pole outputs of the measuring diode bridges are interconnected, and parallel to the outputs of these bridges there are connected measuring filters, between the free points of which a voltmeter is connected and two outputs of the switch into three positions, the third output of which is connected to the common point of the measuring diode bridges, while the relay element is connected with its input to the output of the control unit rectifier. AI u f Kj40 LLJ.JTT 39 R / w ..L .fj I-o zgsh