CN109873413B - Method for completely compensating grounding current by matching controllable current source with arc suppression coil - Google Patents
Method for completely compensating grounding current by matching controllable current source with arc suppression coil Download PDFInfo
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- CN109873413B CN109873413B CN201910259662.3A CN201910259662A CN109873413B CN 109873413 B CN109873413 B CN 109873413B CN 201910259662 A CN201910259662 A CN 201910259662A CN 109873413 B CN109873413 B CN 109873413B
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Abstract
The application discloses a method for completely compensating grounding current by matching a controllable current source with an arc suppression coil, which comprises the following steps: when the system normally operates, detecting each line voltage and detecting a first neutral point voltage; short-circuiting a damping resistor connected in series with the arc suppression coil; detecting the voltage of a second neutral point, relieving the short-circuit state of a damping resistor connected in series with the arc suppression coil, and calculating the ground distributed impedance of a system circuit; calculating the current to be output when the controllable current source completely compensates the grounding current when each phase generates single-phase grounding according to the ground distributed impedance of the system line; judging whether the system is in single-phase grounding or not; if single-phase grounding occurs, the damping resistors connected in series with the arc suppression coils are short-circuited, and a grounding phase is determined; the controllable current source outputs the current which is required to be output when the controllable current source corresponding to the grounding completely compensates the grounding current. The method and the device have the advantages that the accurate controllable current source can realize the current output value of the grounding current full compensation when the single-phase grounding is realized, the single-phase grounding current full compensation is realized, and the realization and the engineering application are easy.
Description
Technical Field
The application relates to the technical field of single-phase grounding full compensation of a power grid system, in particular to a ground fault disappearance judgment method with a controllable voltage compensation mode.
Background
In a power grid system, particularly in a medium-low voltage power distribution network system, single-phase earth faults account for the absolute majority of the total number of faults. When the system capacitance current exceeds a certain value, the grounding electric arc can not be extinguished automatically when a single-phase grounding fault occurs, and arc overvoltage and other secondary hazards are generated. Low-voltage power distribution networks in China generally adopt a low-current grounding mode, including a neutral point ungrounded mode or a neutral point arc suppression coil grounding mode. When the neutral point is not grounded, the grounding electric arc cannot be extinguished by self, and the personnel safety and the operation safety cannot be guaranteed. Under the mode that the neutral point is grounded through the arc suppression coil, part of the grounding arc can be automatically extinguished under the reactive current effect compensated by the arc suppression coil, but the arc suppression coil can only compensate the reactive current, and the grounding residual current still exists after compensation. Residual current contains certain overcompensation inductive current and active current, and risks of electric shock of people, fire and the like still exist. The purposes of completely extinguishing electric arc and eliminating electric shock danger can be achieved through the full compensation of grounding current, so that the zero current compensation method is a reliable and safe single-phase grounding fault treatment means.
However, the current output value of the controllable current source, which realizes the full compensation of the ground current when the single phase is grounded, cannot be accurately provided in the prior art.
Disclosure of Invention
The application provides a method for completely compensating grounding current by matching a controllable current source with an arc suppression coil, which aims to solve the problem that the current output value of the controllable current source for realizing the full compensation of the grounding current in the single-phase grounding cannot be accurately provided in the prior art.
The application provides a method for completely compensating grounding current by matching a controllable current source with an arc suppression coil, which comprises the following steps:
when the system normally operates, detecting each line voltage and detecting a first neutral point voltage;
short-circuiting a damping resistor connected in series with the arc suppression coil;
detecting the voltage of a second neutral point, relieving the short-circuit state of a damping resistor connected in series with the arc suppression coil, and calculating the ground distributed impedance of a system circuit;
calculating the current to be output when the controllable current source completely compensates the grounding current when each phase generates single-phase grounding according to the ground distribution impedance of the system line;
judging whether the system is in single-phase grounding or not;
if single-phase grounding occurs, the damping resistors connected in series with the arc suppression coils are short-circuited, and a grounding phase is determined;
the controllable current source outputs the current which is required to be output when the controllable current source corresponding to the grounding completely compensates the grounding current.
Further, the system line-to-ground distributed impedance is calculated by the following formula:
wherein: zcDistributing impedance to the system to ground;
ZL1the series impedance of the arc suppression coil and the damping resistor before the damping resistor is short-circuited;
ZL2the impedance of the arc suppression coil after the damping resistor is short-circuited;
E01is a first neutral point voltage;
E02is the second neutral point voltage.
Further, the current to be output when the controllable current source fully compensates the grounding current when the single-phase grounding occurs to each phase is calculated by the following formula:
wherein: i is0In order to generate single-phase grounding, the current which is required to be output by the controllable current source when the grounding current is completely compensated;
Uxthe system line voltage is the line voltage between two phases except the grounding phase;
E02is a second neutral point voltage;
ZL2the impedance of the arc suppression coil after the damping resistor is short-circuited;
Zcdistributing the impedance for the system to ground.
Further, when the system is earthed in a single phase, the damping resistors connected in series with the arc suppression coils are all short-circuited.
Further, the voltage of the second neutral point is not more than 15% of the nominal voltage of the system.
As can be seen from the above embodiments, the present application provides a method for fully compensating a ground current by using a controllable current source in cooperation with an arc suppression coil, where the method includes: when the system normally operates, detecting each line voltage and detecting a first neutral point voltage; short-circuiting a damping resistor connected in series with the arc suppression coil; detecting the voltage of a second neutral point, relieving the short-circuit state of a damping resistor connected in series with the arc suppression coil, and calculating the ground distributed impedance of a system circuit; calculating the current to be output when the controllable current source completely compensates the grounding current when each phase generates single-phase grounding according to the ground distribution impedance of the system line; judging whether the system is in single-phase grounding or not; if single-phase grounding occurs, the damping resistors connected in series with the arc suppression coils are short-circuited, and a grounding phase is determined; the controllable current source outputs the current which is required to be output when the controllable current source corresponding to the grounding completely compensates the grounding current. The embodiment of the application can provide an accurate current output value of the controllable current source for realizing the full compensation of the grounding current when the single-phase grounding is realized, realizes the full compensation of the single-phase grounding current, and is easy to realize and apply in engineering.
Drawings
In order to more clearly explain the technical solution of the present application, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious to those skilled in the art that other drawings can be obtained according to the drawings without any creative effort.
Fig. 1 is a flowchart of a method for fully compensating a ground current by a controllable current source in cooperation with an arc suppression coil according to an embodiment of the present application;
fig. 2 is a schematic view of an application scenario provided in the embodiment of the present application.
Illustration of the drawings:
the system comprises a controllable current source 1, a voltage sensor 2, a calculation unit 3, an arc suppression coil 4, a damping resistor 5, a damping resistor short-circuit switch 6, a grounding transformer 7 and a system grounding distributed capacitor 8.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the technical solutions of the present application will be described in detail and completely with reference to the following specific embodiments of the present application and the accompanying drawings. It should be apparent that the described embodiments are only some of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application. The technical solutions provided by the embodiments of the present application are described in detail below with reference to the accompanying drawings.
Fig. 2 is an application scenario diagram of an embodiment of the present application, and the structure in fig. 2 includes a controllable current source 1, a voltage sensor 2, a calculation unit 3, an arc suppression coil 4, a damping resistor 5, a damping resistor short-circuit switch 6, a grounding transformer 7, and a system ground distribution capacitor 8.
As shown in fig. 2, an embodiment of the present application provides a method for fully compensating a ground current by a controllable current source in cooperation with a crowbar coil, where the method includes:
step S101, detecting each line voltage and detecting a first neutral point voltage when a system normally operates;
step S102, short-circuiting damping resistors connected in series with arc suppression coils;
s103, detecting the voltage of a second neutral point, relieving the short-circuit state of a damping resistor connected in series with an arc suppression coil, and calculating the ground distributed impedance of a system circuit;
step S104, calculating current to be output when the controllable current source completely compensates grounding current when each phase generates single-phase grounding according to the ground distributed impedance of the system line;
s105, judging whether the system is in single-phase grounding or not;
s106, if single-phase grounding occurs, short-circuiting the damping resistors connected in series with the arc suppression coils, and determining a grounding phase;
and S107, outputting the current to be output when the controllable current source corresponding to the ground completely compensates the ground current by the controllable current source.
Further, the system line-to-ground distributed impedance is calculated by the following formula:
wherein: zcDistributing impedance to the system to ground;
ZL1the series impedance of the arc suppression coil and the damping resistor before the damping resistor is short-circuited;
ZL2to damp electricityThe arc suppression coil impedance after short circuit resistance;
E01is a first neutral point voltage;
E02is the second neutral point voltage.
Further, the current to be output when the controllable current source fully compensates the grounding current when the single-phase grounding occurs to each phase is calculated by the following formula:
wherein: i is0In order to generate single-phase grounding, the current which is required to be output by the controllable current source when the grounding current is completely compensated;
Uxthe system line voltage is the line voltage between two phases except the grounding phase;
E02is a second neutral point voltage;
ZL2the impedance of the arc suppression coil after the damping resistor is short-circuited;
Zcdistributing the impedance for the system to ground.
Further, when the system is earthed in a single phase, the damping resistors connected in series with the arc suppression coils are all short-circuited.
Further, the voltage of the second neutral point is not more than 15% of the nominal voltage of the system.
As can be seen from the above embodiments, the present application provides a method for fully compensating a ground current by using a controllable current source in cooperation with an arc suppression coil, where the method includes: when the system normally operates, detecting each line voltage and detecting a first neutral point voltage; short-circuiting a damping resistor connected in series with the arc suppression coil; detecting the voltage of a second neutral point, relieving the short-circuit state of a damping resistor connected in series with the arc suppression coil, and calculating the ground distributed impedance of a system circuit; calculating the current to be output when the controllable current source completely compensates the grounding current when each phase generates single-phase grounding according to the ground distribution impedance of the system line; judging whether the system is in single-phase grounding or not; if single-phase grounding occurs, the damping resistors connected in series with the arc suppression coils are short-circuited, and a grounding phase is determined; the controllable current source outputs the current which is required to be output when the controllable current source corresponding to the grounding completely compensates the grounding current. The embodiment of the application can provide an accurate current output value of the controllable current source for realizing the full compensation of the grounding current when the single-phase grounding is realized, realizes the full compensation of the single-phase grounding current, and is easy to realize and apply in engineering. Other embodiments of the present application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. This application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the application and including such departures from the present disclosure as come within known or customary practice within the art to which the invention pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the application being indicated by the following claims.
It will be understood that the present application is not limited to the precise arrangements described above and shown in the drawings and that various modifications and changes may be made without departing from the scope thereof. The scope of the application is limited only by the appended claims.
Claims (5)
1. A method for fully compensating grounding current by matching a controllable current source with an arc suppression coil is characterized by comprising the following steps:
when the system normally operates, detecting each line voltage and detecting a first neutral point voltage;
short-circuiting a damping resistor connected in series with the arc suppression coil;
detecting the voltage of a second neutral point, relieving the short-circuit state of a damping resistor connected in series with the arc suppression coil, and calculating the ground distributed impedance of a system circuit;
calculating the current to be output when the controllable current source completely compensates the grounding current when each phase generates single-phase grounding according to the ground distribution impedance of the system line;
judging whether the system is in single-phase grounding or not;
if single-phase grounding occurs, the damping resistors connected in series with the arc suppression coils are short-circuited, and a grounding phase is determined;
the controllable current source outputs the current which is required to be output when the controllable current source corresponding to the grounding completely compensates the grounding current.
2. The method for fully compensating the grounding current by the cooperation of the controllable current source and the arc suppression coil according to claim 1, wherein the distribution impedance of the system line to the ground is calculated by the following formula:
wherein: zcDistributing impedance to the system to ground;
ZL1the series impedance of the arc suppression coil and the damping resistor before the damping resistor is short-circuited;
ZL2the impedance of the arc suppression coil after the damping resistor is short-circuited;
E01is a first neutral point voltage;
E02is the second neutral point voltage.
3. The method of claim 1, wherein the current to be output when the ground current is fully compensated by the controllable current source when the single-phase ground occurs in each phase is calculated by the following formula:
wherein: i is0In order to generate single-phase grounding, the current which is required to be output by the controllable current source when the grounding current is completely compensated;
Uxthe system line voltage is the line voltage between two phases except the grounding phase;
E02is a second neutral point voltage;
ZL2the impedance of the arc suppression coil after the damping resistor is short-circuited;
Zcdistributing the impedance for the system to ground.
4. A method as claimed in claim 1, wherein the damping resistors connected in series with the arc suppression coil are all short-circuited when the system is in single-phase grounding.
5. A method as claimed in claim 1, wherein the voltage of the second neutral point is not more than 15% of the nominal voltage of the system.
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| CN101552466B (en) * | 2009-03-18 | 2011-05-18 | 中冶赛迪工程技术股份有限公司 | An arc-suppression coil grounding device for medium voltage network |
| CN104901299A (en) * | 2015-06-19 | 2015-09-09 | 安徽马尼特合开电器有限公司 | Resonant grounding system automatic tracking and compensating device and method |
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