CN113078622B - Resistance type direct current magnetic bias suppression system - Google Patents
Resistance type direct current magnetic bias suppression system Download PDFInfo
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- CN113078622B CN113078622B CN202110451901.2A CN202110451901A CN113078622B CN 113078622 B CN113078622 B CN 113078622B CN 202110451901 A CN202110451901 A CN 202110451901A CN 113078622 B CN113078622 B CN 113078622B
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- current transformer
- thyristor
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- 230000001629 suppression Effects 0.000 title claims abstract description 18
- 230000007935 neutral effect Effects 0.000 claims abstract description 31
- 230000001052 transient effect Effects 0.000 claims abstract description 21
- 238000001514 detection method Methods 0.000 claims description 3
- 238000004891 communication Methods 0.000 claims description 2
- 230000000903 blocking effect Effects 0.000 description 3
- 239000003990 capacitor Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000001960 triggered effect Effects 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical group [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000005288 electromagnetic effect Effects 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000013021 overheating Methods 0.000 description 1
Classifications
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
- H02H9/005—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection avoiding undesired transient conditions
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/04—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for transformers
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/04—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for transformers
- H02H7/042—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for transformers for current transformers
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
- H02H9/04—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess voltage
- H02H9/044—Physical layout, materials not provided for elsewhere
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
- H02H9/04—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess voltage
- H02H9/045—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess voltage adapted to a particular application and not provided for elsewhere
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Emergency Protection Circuit Devices (AREA)
- Control Of Electrical Variables (AREA)
Abstract
The invention discloses a resistance type direct current magnetic bias suppression system which comprises an adjustable resistor, a fast acting switch, a bridge rectifier, a transient voltage trigger unit, a current transformer unit, a thyristor and an adjustable resistor control unit. The bridge rectifier and the thyristor are connected in series and then connected with the adjustable resistor and the fast acting switch in parallel, one end of the bridge rectifier and the thyristor is connected with the neutral point of the transformer, and the other end of the bridge rectifier and the thyristor is directly grounded. The overvoltage triggering unit is used for triggering the thyristor to conduct and the fast-acting switch to close. The current transformer unit comprises a Hall current transformer and a Rogowski coil current transformer, wherein the Rogowski coil current transformer is used for detecting neutral point alternating current and transient current and is used as a control signal for switching off a fast acting switch; the Hall current transformer is used for detecting neutral point direct current, the direct current is transmitted to the adjustable resistor control unit, and the adjustable resistor control unit adjusts the resistance value of the adjustable resistor to enable the direct current to be smaller than 10A. The device can automatically change the grounding mode of the transformer according to the field requirement.
Description
Technical Field
The present invention relates to a resistive dc magnetic bias suppression system, and more particularly, to a resistive dc magnetic bias suppression system capable of automatically changing a grounding mode of a transformer.
Background
Dc bias refers to the occurrence of a dc component in the exciting current of a transformer, resulting in saturation of the transformer core half-cycle and thus a series of electromagnetic effects. When direct current enters the transformer, the half-cycle magnetic saturation of the transformer core and the increase of magnetic leakage are caused, and the overheating of the metal structural component and the oil tank is caused; the magnetic bias of direct current can also cause the magnetostriction of the iron core to be more serious, so that the vibration and noise of the transformer are increased; meanwhile, due to harmonic distortion, the loss of the transformer is increased, and the efficiency is reduced; even directly causes transformer damage and power supply tripping when the direct current magnetic bias is serious. Therefore, the direct current magnetic bias has a great potential safety hazard for the safe operation of the power system.
The reason for generating DC magnetic bias is mainly that the DC transmission line runs in a single pole or asymmetrically, and the solar magnetic storm, the former is the main reason for generating DC magnetic bias in China.
The normal operation of the transformer with 110kV and above generally adopts a neutral point direct grounding mode, but if the transformer in the region has larger direct current magnetic bias risk, a capacitive or resistive direct current magnetic bias suppression device is additionally arranged at the neutral point of the transformer.
Because the capacitor has the function of isolating direct current from alternating current, the neutral point of the transformer cannot pass through direct current after being connected into the capacitor. Therefore, the dc blocking effect of the capacitive device is not affected by the magnitude of the dc current, as compared to the resistive device. However, the blocking device is used for completely blocking current, and direct current in the ground can enter a transformer adjacent to a transformer substation, so that the direct current magnetic bias problem occurs in a new station.
The resistance type device increases the resistance of the neutral point direct current loop of the transformer, and can inhibit the direct current magnetic bias current of the neutral point at the same time with certain current flowing capability, so that the resistance type device is more effective in treating the direct current magnetic bias of the regional power grid under the condition that the direct current magnetic bias current is not large (not more than 50A). At present, the direct current magnetic bias problem of the regional power grid is often treated by adopting a mode of combining capacitance and resistance in engineering.
The resistor current limiting device adopts a mode of connecting a high-power resistor in series with the neutral point of the transformer, and increases the direct-current impedance of a power grid system, so that the direct-current magnetic bias current entering the transformer is restrained. The current connected resistor device is generally a 3-5 ohm pure resistor, and the structure of the device is simpler. But the zero sequence impedance of the power grid is greatly increased by the connection of the resistor device, and the accuracy of the relay protection and fault location system and even the protection misoperation can be influenced under the short-circuit grounding and overvoltage working conditions of the system.
Disclosure of Invention
The invention aims to overcome the defects of the prior art, and provides a resistance type direct current magnetic bias suppression system, wherein an overvoltage quick bypass protection loop is arranged outside an original resistor, and when the voltage is detected to exceed a set threshold value, the protection loop is quickly conducted, so that the transformer is directly grounded, the circuit topology is restored to a state without neutral point resistance, and the correct protection action is ensured. And meanwhile, a current transformer is used for detecting neutral point alternating current and transient current and is used for controlling the disconnection of a fast switch, the transformer is restored to the grounding mode of a resistor, and the direct current magnetic bias in a system loop is restrained so as to realize automatic change of the grounding mode of the transformer.
The technical scheme adopted by the invention is as follows:
The direct-current magnetic bias suppression device consists of an adjustable resistor, a fast-acting switch, a rectifying module, a transient voltage triggering unit, a current transformer unit, a thyristor and an adjustable resistor control unit; the rectifier module and the thyristor are connected in series and then connected with the adjustable resistor and the fast acting switch in parallel, one end of the rectifier module and the thyristor are connected with the neutral point of the transformer, and the other end of the rectifier module and the thyristor are directly grounded;
the high-voltage end of the overvoltage triggering unit is connected to the upper end of the thyristor and is used for triggering the thyristor to conduct;
the current transformer unit comprises a Hall current transformer and a Rogowski coil current transformer, wherein the Rogowski coil current transformer is used for detecting neutral point alternating current and transient current, and the Hall current transformer is used for detecting neutral point direct current;
The Hall current transformer is in communication connection with the adjustable resistor control unit, and the adjustable resistor control unit adjusts the resistance value of the adjustable resistor according to neutral point direct current detected by the Hall current transformer, so that the direct current is smaller than 10A;
The fast acting switch acts according to the detection result of the overvoltage triggering unit and the rogowski coil current transformer: the fast acting switch is closed when the overvoltage signal detected by the overvoltage triggering unit exceeds a voltage threshold value, and is opened when the alternating current and transient current signals detected by the rogowski coil current transformer are lower than a current threshold value.
Further, the method comprises the step of connecting a plurality of thyristors in parallel.
Further, the rated current of the thyristor is not lower than 5000A, and the surge current is not lower than 70kA/20ms.
Further, the resistance value range of the adjustable resistor is 1-6 ohms, and the minimum adjusting gear is 0.5 ohms.
Further, the current threshold is 100A.
The invention provides a resistance type direct current magnetic bias suppression system, wherein an overvoltage quick bypass protection loop is arranged outside an original resistor, when the voltage is detected to exceed a set threshold value, the protection loop is quickly conducted, the direct grounding of a transformer is realized, the circuit topology is restored to a state without neutral point resistance, and the correct protection action is ensured. And meanwhile, a current transformer is used for detecting neutral point alternating current and transient current and is used for controlling the disconnection of a fast switch, and the transformer is restored to the resistor grounding mode to inhibit direct current magnetic bias in a system loop. The resistance type direct current magnetic bias suppression system can automatically change the grounding mode of the transformer according to the field requirement.
In addition, the resistance type direct current magnetic bias suppression system adopts the thyristor as a switching element, so that the response time can reach us level, and the response time is greatly faster than the action time of a conventional gap or switch.
Drawings
The invention is further described below with reference to the drawings and examples;
FIG. 1 is a schematic circuit diagram of a resistive DC bias suppression system of the present invention;
FIG. 2 is a flow chart of the resistive DC bias suppression system of the present invention;
In the figure, N is the neutral point of the transformer; r1 is an adjustable resistor; k1 is a fast acting switch; BR is a bridge rectifier; t1 is a transient voltage trigger unit; th is a thyristor; CT is a current sensor unit; KT is an adjustable resistance control unit.
Detailed Description
The invention provides a resistance type direct current magnetic bias suppression system, as shown in fig. 1-2, wherein the direct current magnetic bias suppression device consists of an adjustable resistor R1, a fast acting switch K1, a bridge rectifier BR, a transient voltage trigger unit T1, a current transformer unit CT, a thyristor Th and an adjustable resistor control unit KT. Wherein:
the head end of the adjustable resistor R1 is connected with the neutral point of the transformer, and the tail end of the adjustable resistor R1 is directly grounded.
The fast acting switch K1 is connected in parallel with the adjustable resistor R1. When the fast bypass switch is closed, the neutral point of the transformer is directly grounded; whereas the transformer is grounded through a resistor.
The bridge rectifier BR and the thyristor Th are connected in series and then connected with the adjustable resistor R1 and the fast acting switch K1 in parallel. The bridge rectifier BR can ensure that the voltage applied to the overvoltage triggering unit and the thyristor is a forward voltage; the overvoltage triggering unit T1 is connected to the upper end of the thyristor Th in a high-voltage mode and is used for triggering the thyristor Th to conduct and triggering the fast-acting switch K1 to close. When a system short circuit fault, lightning intrusion waves and operation overvoltage occur, the voltage at two ends of the adjustable resistor R1 is increased sharply, when the voltage is higher than a voltage threshold U0 (set to 10 kV) on the transient voltage trigger unit T1, the transient voltage trigger unit T1 is conducted, meanwhile, the thyristor Th is triggered to conduct and the fast acting switch K1 is triggered to close, and as the response time of the thyristor Th is of the us level, the neutral point is directly grounded through the thyristor Th at the us level time. Since the overvoltage triggering unit T1 triggers the thyristor Th and the fast-acting switch K1 at the same time, the thyristor Th is turned on while the thyristor K1 is fast closed, and the action time is less than 20ms. The neutral point of the transformer can be quickly grounded in a parallel connection mode of the thyristor Th and the quick action switch K1, and the influence of the device resistance on relay protection is eliminated.
The protection thyristor Th adopts a large-capacity high-voltage thyristor, the general rated current is not less than 5000A, the surge through current is not less than 70kA/20ms, and the time coordination of the fast switch is satisfied. The safety margin can be improved in a mode of connecting a plurality of high-voltage thyristors in series and parallel when necessary.
The current transformer unit CT includes a rogowski coil current transformer for detecting neutral ac and transient current, and a current signal is used to control the fast acting switch K1 to be turned off through the signal loop 2.
The fast acting switch K1 is controlled by the detection results of the transient voltage trigger unit T1 and the current transformer unit CT at the same time, and as shown in figure 2, when the voltage of the transient voltage trigger unit T1 is higher than a threshold value, the switch K1 is controlled to be closed, and the adjustable resistor R1 is bypassed; when the system overvoltage disappears, the transient current of the neutral point will disappear, and the neutral point alternating current is restored to the normal level at the moment, so that the current of the signal loop 2 is set to be smaller than the current threshold I 0 (set to be 100A), K1 is disconnected, and the neutral point of the transformer is restored to the resistor to be grounded at the moment, and the direct current magnetic bias in the system loop is restrained. The grounding mode of the transformer can be automatically changed according to the field requirement through the coordination of the signal control loops 2 and 3.
In addition, the current transformer unit CT further includes a hall current transformer, where the hall current transformer is used to detect neutral point dc current, and the current enters the adjustable resistance control unit KT through the signal loop 1, and the adjustable resistance control unit KT is used to adjust the gear of the adjustable resistance R1 until the dc current is less than 10A, so that the transformer is not easy to damage.
It is apparent that the above examples are given by way of illustration only and are not limiting of the embodiments. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary or exhaustive of all embodiments. And obvious variations or modifications thereof are contemplated as falling within the scope of the present invention.
Claims (3)
1. The resistance type direct current magnetic bias suppression system is characterized by comprising an adjustable resistor, a fast acting switch, a rectifying module, a transient voltage trigger unit, a current transformer unit, a plurality of thyristors which are connected in parallel and an adjustable resistor control unit; the rectifier module and the thyristors connected in parallel are connected in series and then connected with the adjustable resistor and the fast acting switch in parallel, one end of the rectifier module is connected with the neutral point of the transformer, and the other end of the rectifier module is directly grounded; the resistance value range of the adjustable resistor is 1-6 ohms, and the minimum adjusting gear is 0.5 ohms;
The high-voltage end of the transient voltage trigger unit is connected to the upper end of the thyristor and is used for triggering the thyristor to conduct;
the current transformer unit comprises a Hall current transformer and a Rogowski coil current transformer, wherein the Rogowski coil current transformer is used for detecting neutral point alternating current and transient current, and the Hall current transformer is used for detecting neutral point direct current;
The Hall current transformer is in communication connection with the adjustable resistor control unit, and the adjustable resistor control unit adjusts the resistance value of the adjustable resistor according to neutral point direct current detected by the Hall current transformer, so that the direct current is smaller than 10A;
The fast acting switch acts according to the detection result of the transient voltage trigger unit and the rogowski coil current transformer: the fast acting switch is closed when the overvoltage signal detected by the transient voltage trigger unit exceeds a voltage threshold value, and is opened when the alternating current and transient current signals detected by the rogowski coil current transformer are lower than a current threshold value.
2. A resistive dc bias suppression system according to claim 1, wherein the thyristor has a rated current of not less than 5000A and a surge through current of not less than 70kA/20ms.
3. A resistive dc bias suppression system according to claim 1, wherein said current threshold is 100A.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110451901.2A CN113078622B (en) | 2021-04-26 | 2021-04-26 | Resistance type direct current magnetic bias suppression system |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110451901.2A CN113078622B (en) | 2021-04-26 | 2021-04-26 | Resistance type direct current magnetic bias suppression system |
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| Publication Number | Publication Date |
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| CN113078622A CN113078622A (en) | 2021-07-06 |
| CN113078622B true CN113078622B (en) | 2024-10-01 |
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| CN202110451901.2A Active CN113078622B (en) | 2021-04-26 | 2021-04-26 | Resistance type direct current magnetic bias suppression system |
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| CN114825295A (en) * | 2022-01-19 | 2022-07-29 | 湖州电力设计院有限公司 | Self-adjusting resistance type direct current magnetic bias suppression device |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN214958692U (en) * | 2021-04-26 | 2021-11-30 | 金华电力设计院有限公司 | Resistance type direct current magnetic bias suppression device |
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| CN2847637Y (en) * | 2005-11-18 | 2006-12-13 | 中国电力科学研究院 | Device for suppressing transformer neutral point DC current by capacitance method |
| CN102709881B (en) * | 2012-03-15 | 2015-04-22 | 东北电力科学研究院有限公司 | Device utilizing adjustable resistance method to curb DC of neutral point of transformer |
| KR102758890B1 (en) * | 2018-09-28 | 2025-01-23 | 테크홀드, 엘엘씨 | Grid protection through transformer neutral disconnection system and triggered phase disconnection |
| CN211266466U (en) * | 2019-12-17 | 2020-08-14 | 丽水市正阳电力设计院有限公司 | Device is administered to main neutral point comprehensive direct current magnetic biasing that becomes |
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| CN214958692U (en) * | 2021-04-26 | 2021-11-30 | 金华电力设计院有限公司 | Resistance type direct current magnetic bias suppression device |
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