CN210838926U - Alternating current intrusion and high voltage counterattack protection device for direct current system of transformer substation - Google Patents
Alternating current intrusion and high voltage counterattack protection device for direct current system of transformer substation Download PDFInfo
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- CN210838926U CN210838926U CN201921365658.7U CN201921365658U CN210838926U CN 210838926 U CN210838926 U CN 210838926U CN 201921365658 U CN201921365658 U CN 201921365658U CN 210838926 U CN210838926 U CN 210838926U
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- 230000001419 dependent effect Effects 0.000 claims description 3
- 230000009545 invasion Effects 0.000 abstract description 10
- 230000006378 damage Effects 0.000 description 8
- 238000009792 diffusion process Methods 0.000 description 3
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- 238000000034 method Methods 0.000 description 3
- 230000002159 abnormal effect Effects 0.000 description 2
- 230000002401 inhibitory effect Effects 0.000 description 2
- 238000009413 insulation Methods 0.000 description 2
- 230000002829 reductive effect Effects 0.000 description 2
- 230000001052 transient effect Effects 0.000 description 2
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
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Abstract
The utility model discloses a direct current system of transformer substation exchanges invasion and high pressure counterattack protection device, including first diode, second diode, LC series connection filtering branch road, piezo-resistor, voltmeter, automobile starting motor relay and NTC thermistor, the positive generating line of transformer substation direct current system, second diode negative pole connect the direct current system negative bus of transformer substation, the negative pole of first diode with the second diode positive pole links to each other and ground connection, after LC series connection filtering branch road and NTC thermistor establish ties with the series circuit of first diode and second diode is parallelly connected, two piezo-resistor's series circuit both ends link to each other with direct current system positive bus and negative bus respectively, automobile starting motor relay one end is connected with direct current system positive bus or negative bus, and the other end is connected with the earthing terminal. The device maintains the stability of the direct current bus to the ground voltage, solves the problem of huge potential difference generated by high-voltage counterattack, and improves the operation reliability of a power grid.
Description
Technical Field
The utility model relates to a circuit protection device especially relates to a direct current system of transformer substation exchanges invasion and high-pressure counterattack protection device.
Background
The direct current system of the transformer substation plays a very important role in auxiliary equipment of the transformer substation, but due to the particularity of the transformer substation, the direct current system in the transformer substation is more easily interfered by external factors such as lightning wave intrusion, alternating current intrusion and direct current grounding than other occasions, and the interference not only can damage secondary equipment, but also can cause serious accidents such as switch error jump. The alternating current intrusion is an abnormal phenomenon that a secondary alternating current power supply of a transformer substation is connected into a direct current system in series, so that the voltage to ground of a direct current bus fluctuates greatly at the frequency of 50 Hz. The high-voltage counterattack is that the direct current system encounters a flashover caused by a huge potential difference generated by grounding of primary equipment, and any weak link in the direct current system can be seriously damaged. The existing direct current system better solves the problems of lightning wave invasion and direct current grounding by means of additionally arranging a lightning arrester, a direct current insulation monitoring device and the like, but an effective solution for alternating current invasion does not exist, and the damage of high voltage counterattack cannot be effectively coped with.
Chinese patent document CN203135401U discloses a "transformer substation dc system ac intrusion protection device". The air switch comprises a first diode, a second diode, an air switch and an alternating current voltmeter, wherein the negative electrode of the first diode is connected with the positive electrode of the second diode and then connected with a grounding terminal, the positive electrode of the first diode and the negative electrode of the second diode are respectively connected with the wire outlet end of the air switch, and the wire inlet end of the air switch is connected with a direct current bus. The air switch and the diode are arranged between the direct current bus and the ground, so that accidents possibly caused by the fact that alternating current invades a direct current system can be effectively avoided; the voltage clamping effect of the diode is utilized to ensure the relative stability of the voltage to ground of the direct current bus; and an alarm signal contact is provided externally by using an auxiliary contact of the alternating-current voltmeter, so that an alarm function is realized. When the device faces to an alternating voltage, the stability of a direct current bus to a ground voltage cannot be effectively maintained, and meanwhile, the damage of high-voltage counterattack to a direct current system cannot be solved.
Disclosure of Invention
The utility model discloses mainly solve original direct current bus to ground voltage unstable and can't solve the technical problem of the destruction that high pressure counterattack caused direct current system, provide a transformer substation's direct current system exchanges invasion and high pressure counterattack protection device, effectively maintain the stability of direct current bus to ground voltage to reduce by a wide margin because of direct current system receives the accident probability that alternating current disturbed and lead to, solve the huge potential difference that high pressure counterattack produced and improve electric wire netting operational reliability to direct current system's destruction.
The above technical problem of the present invention can be solved by the following technical solutions: the utility model discloses a first diode, second diode, LC series connection filtering branch road, piezo-resistor, voltmeter, automobile starting motor relay and NTC thermistor, the positive generating line that connects the direct current system of transformer substation, second diode negative pole connect the direct current system of transformer substation negative bus of first diode, the negative pole of first diode with the second diode positive pole links to each other and links to each other with the earthing terminal, after LC series connection filtering branch road and NTC thermistor establish ties with the series circuit of first diode and second diode is parallelly connected, two piezo-resistor's series circuit's both ends link to each other with direct current system positive generating line and direct current system negative bus respectively, automobile starting motor relay's one end and direct current system positive bus or negative bus are connected, and the other end is connected with the earthing terminal, two measurement input ends of voltmeter respectively with direct current system positive bus, The negative bus bar is connected. The cathode of the first diode is connected with the anode of the second diode and grounded, and the diode is used for inhibiting the direct current bus from being grounded. The LC series filtering branch circuit is connected with the NTC thermistor in series and then connected with the first diode or the second diode in parallel, so that the power frequency voltage can be short-circuited to the ground through the resonant circuit, and the voltage of the direct-current bus to the ground is stable. The voltage-dependent resistor is used for suppressing the diffusion of overvoltage invasion waves, the contact of the relay of the automobile starting motor has very large through-current capacity and strong arc extinguishing capacity, the capacity of bearing the reverse impact of alternating-current high voltage is much stronger than that of a common intermediate relay or a contactor, and the voltmeter is used for measuring the size of the invasion alternating-current voltage and giving an alarm when the alternating-current invades, so that the personnel can conveniently find and process the invasion.
Preferably, the LC series filtering branch comprises an inductor and a capacitor connected in series, and the capacitance of the capacitor is less than 3 microfarads. The method is used for reducing the capacitance component of the direct current bus to the ground and preventing switch mis-tripping accidents possibly caused by direct current grounding of a switch operation loop.
Preferably, the resonant frequency of the LC series filtering branch is power frequency. When alternating current invades, the voltage to ground of the direct current bus fluctuates greatly at the frequency of 50 Hz.
Preferably, the rated current of the first diode and the rated current of the second diode are not lower than 100A, and the rated reverse withstand voltage is not lower than 1000V. The circuit is used for ensuring that the diode is not damaged when the diode bears serious alternating current intrusion.
Preferably, the breakdown threshold voltage of the piezoresistor is 1.2 times of the rated voltage of the direct-current system.
Preferably, the cold resistance of the NTC thermistor is between 50 and 200 ohms.
The utility model has the advantages that: the stability of the voltage to ground of the direct current bus is effectively maintained, so that the accident probability caused by alternating current interference of the direct current system is greatly reduced, the damage of a huge potential difference generated by high-voltage counterattack to the direct current system is solved, and the operation reliability of a power grid is improved.
Drawings
Fig. 1 is a circuit connection diagram of the present invention.
In the figure, 1 a first diode, 2 a second diode, 3 LC series filtering branch circuits, 3.1 inductors, 3.2 capacitors, 4 piezoresistors, 5 voltmeters, 6 automobile starting motor relays, 6.1 quick contacts, 6.2 coils, 7 NTC thermistors, 10 direct-current system positive buses and 20 direct-current system negative buses
Detailed Description
The technical solution of the present invention is further specifically described below by way of examples and with reference to the accompanying drawings.
Example (b): the ac intrusion and high-voltage counterattack protection device for a dc system of a transformer substation in this embodiment, as shown in fig. 1, includes a first diode 1, a second diode 2, an LC series filter branch 3, a voltage dependent resistor 4, a voltmeter 5, an automobile starting motor relay 6, and an NTC thermistor 7. The positive electrode of the first diode 1 is connected with a positive bus 10 of a direct current system of the transformer substation, the negative electrode of the second diode 2 is connected with a negative bus 20 of the direct current system of the transformer substation, the negative electrode of the first diode 1 is connected with the positive electrode of the second diode 2 and is connected with a grounding end, the diodes are used for inhibiting the direct current bus from being grounded, the rated current of the first diode 1 and the rated current of the second diode 2 are not lower than 100A, and the rated reverse withstand voltage is not lower than 1000V, so that the diodes are prevented from being damaged when being subjected to serious alternating current intrusion. The LC series filtering branch circuit 3 is connected with the NTC thermistor 7 in series and then connected with the series circuit of the first diode 1 and the second diode 2 in parallel, the cold resistance of the NTC thermistor 7 is between 50 and 200 ohms, and the thermistor 7 is used for attenuating the transient component of the voltage fluctuation of the direct-current bus to the ground, so that the transient current of the LC filtering branch circuit 3 is prevented from instantaneously influencing the stability of the voltage fluctuation of the direct-current bus to the ground. The resonance frequency of the LC series filtering branch circuit 3 is power frequency, so that the power frequency voltage can be short-circuited to the ground through the resonance circuit, and the voltage to the ground of the direct-current bus is stable. The LC series filtering branch circuit 3 comprises an inductor 3.1 and a capacitor 3.2 which are connected in series, and the capacity of the capacitor 3.2 is less than 3 microfarads, so that the capacitance component of a direct current bus to ground is reduced, and switching error tripping accidents possibly caused by direct current grounding of a switching operation loop are prevented. The series circuit of the two piezoresistors 4 is connected in series between a positive bus and a negative bus of the direct current system, the piezoresistors 4 are used for suppressing the diffusion of overvoltage invasion waves, and the breakdown threshold voltage of the piezoresistors 4 is 1.2 times of the rated voltage of the direct current system. One end of the automobile starting motor relay 6 is connected with the direct-current system positive bus 10 or the direct-current system negative bus 20, the other end of the automobile starting motor relay is connected with the grounding end, the automobile starting motor relay 6 comprises a quick contact 6.1 and a coil 6.2, one end of the coil 6.2 is located between the two piezoresistors 4 which are connected in series, and the other end of the coil is located between the negative electrode of the first diode 1 and the positive electrode of the second diode 2. The automobile starting motor relay 6 has the advantages that the contact through-current capacity is large, the arc extinguishing capacity is high, the capacity of bearing alternating-current high-voltage counterattack is much stronger than that of a common intermediate relay or a contactor, the measuring input end of the voltmeter 5 is connected with the positive bus and the negative bus of the direct-current system respectively and used for measuring the size of the invading alternating-current voltage, an alarm is given when alternating-current invades, and people can conveniently find and process the invading alternating-current voltage.
The alternating current intrusion is an abnormal phenomenon that a secondary alternating current power supply of a transformer substation is connected into a direct current system in series, so that the voltage to ground of a direct current bus fluctuates greatly at the frequency of 50 Hz. Since 110/220V direct current of the transformer substation is an ungrounded system, once an alternating current component grounded for some reason is connected in series into the direct current system, a large alternating current voltage to ground is superposed on a direct current bus, and the alternating current component invading into the direct current system is applied to some intermediate relays through cable distributed capacitors and bus ground capacitors of all direct current loops, so that serious accidents of switch misoperation can be caused. The most obvious phenomenon after an alternating current component enters a direct current system is that the voltage to ground of a whole direct current loop fluctuates greatly at the frequency of 50Hz, and if the voltage fluctuation can be attenuated to be small enough, the damage of the alternating current to the direct current system after entering can be effectively relieved, so that the key point is to stabilize the voltage to ground of a direct current bus to improve the capability of the direct current system for resisting the intrusion of the alternating current. When alternating current intrusion occurs, since the cathode of the first diode 1 and the anode of the second diode 2 are grounded, the series-connected alternating current component can be controlled by suppressing the bus voltage to ground through the diodes. When the direct current system is normal, due to the potential relation among the positive bus, the earth and the negative bus, the two diodes are not conducted, and the silicon diode has infinite reverse impedance, so that the insulation of the bus to the earth cannot be influenced; when the bus is in direct current grounding, the phenomenon that the potential of the negative bus is higher than the ground or the potential of the positive bus is lower than the ground is not possible, so that the diode is still not conducted and can be regarded as not to exist; after the alternating current component is connected in series with the direct current system, if the alternating current component is connected in series with the negative pole, the positive half cycle of the alternating current is short-circuited through the second diode 2, and if the alternating current component is connected in series with the positive pole, the negative half cycle of the alternating current is short-circuited through the first diode 1, so that the small air switch of the alternating current loop or the direct current branch is forced to trip rapidly, and the invasive alternating current component is cut off. If the amplitude of the invaded alternating current component is large (high-voltage counterattack), the voltage clamping effect of the diode can ensure that the direct current bus is relatively stable to the ground voltage, and at least the invaded high-voltage alternating current can not flow into other loops any more.
The high-voltage counterattack is that the direct current system encounters a flashover caused by a huge potential difference generated by grounding of primary equipment, and any weak link in the direct current system can be seriously damaged. After the high voltage is reversely struck, the voltage of the direct current system is inevitably and rapidly increased, at the moment, the piezoresistor 4 is rapidly broken down and conducted, on one hand, the diffusion of overvoltage invasion waves is suppressed, on the other hand, the quick contact 6.1 of the automobile starting motor relay 6 is enabled to act and close through the excitation of the relay coil 6.2, after the quick contact 6.1 is closed, the direct current system is directly grounded at the same pole, and the ground potential of the direct current system is instantly inhibited, because the automobile starting motor relay 6 is a direct current relay with large contact through-current capacity and strong arc extinguishing capacity, the direct current relay is much stronger than the capacity of a common intermediate relay or contactor for bearing the alternating current high voltage. The utility model discloses a piezo-resistor combines with automobile starting motor relay's ingenious, is applied to automobile starting motor relay and strikes against at electric current high pressure, and the effect is showing and with low costs, effectively maintains the stability of direct current bus to ground voltage simultaneously to reduce by a wide margin because of direct current system receives the accident probability that alternating current disturbance leads to, solve the huge potential difference that the high pressure strikes the production and to direct current system's destruction, improve electric wire netting operational reliability.
Claims (6)
1. A transformer substation direct current system alternating current intrusion and high-voltage counterattack protection device is characterized by comprising a first diode (1), a second diode (2), an LC series filtering branch (3), two piezoresistors (4), a voltmeter (5), an automobile starting motor relay (6) and an NTC thermistor (7), wherein the anode of the first diode (1) is connected with a transformer substation direct current system positive bus (10), the cathode of the second diode (2) is connected with a transformer substation direct current system negative bus (20), the cathode of the first diode (1) is connected with the anode of the second diode (2) and is connected with a grounding end, the LC series filtering branch (3) is connected with the NTC thermistor (7) in series and then is connected with the series circuit of the first diode (1) and the second diode (2) in parallel, two ends of the series circuit of the two piezoresistors (4) are respectively connected with the direct current system positive bus (10) and the direct current system negative bus (20), one end of the automobile starting motor relay (6) is connected with a positive bus or a negative bus of the direct current system, the other end of the automobile starting motor relay is connected with a grounding end, and two measuring input ends of the voltmeter (5) are respectively connected with the positive bus and the negative bus of the direct current system.
2. A substation dc system ac intrusion and high voltage counterattack protection device according to claim 1, characterized in that the LC series filter branch (3) comprises an inductor (3.1) and a capacitor (3.2) connected in series, the capacity of the capacitor (3.2) being less than 3 microfarads.
3. The alternating current intrusion and high voltage counterattack protection device for the direct current system of the transformer substation as claimed in claim 2, wherein the resonance frequency of the LC series filter branch circuit (3) is the power frequency.
4. The alternating current intrusion and high voltage counterattack protection device for the substation direct current system according to claim 1, wherein the rated current of the first diode (1) and the rated current of the second diode (2) are not lower than 100A, and the rated reverse voltage resistance is not lower than 1000V.
5. The alternating current intrusion and high voltage counterattack protection device for the substation direct current system according to claim 1, wherein the breakdown threshold voltage of the voltage dependent resistor (4) is 1.2 times the rated voltage of the direct current system.
6. A substation dc system ac intrusion and high voltage counterattack protection device according to claim 1, characterized in that the NTC thermistor (7) has a cold resistance between 50 and 200 ohms.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201921365658.7U CN210838926U (en) | 2019-08-21 | 2019-08-21 | Alternating current intrusion and high voltage counterattack protection device for direct current system of transformer substation |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201921365658.7U CN210838926U (en) | 2019-08-21 | 2019-08-21 | Alternating current intrusion and high voltage counterattack protection device for direct current system of transformer substation |
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| Publication Number | Publication Date |
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| CN210838926U true CN210838926U (en) | 2020-06-23 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN201921365658.7U Active CN210838926U (en) | 2019-08-21 | 2019-08-21 | Alternating current intrusion and high voltage counterattack protection device for direct current system of transformer substation |
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| Country | Link |
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| CN (1) | CN210838926U (en) |
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- 2019-08-21 CN CN201921365658.7U patent/CN210838926U/en active Active
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