CN109378797B - High-voltage overhead line disconnection protection and identification method - Google Patents
High-voltage overhead line disconnection protection and identification method Download PDFInfo
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H5/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal non-electric working conditions with or without subsequent reconnection
- H02H5/10—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal non-electric working conditions with or without subsequent reconnection responsive to mechanical injury, e.g. rupture of line, breakage of earth connection
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/08—Locating faults in cables, transmission lines, or networks
- G01R31/081—Locating faults in cables, transmission lines, or networks according to type of conductors
- G01R31/085—Locating faults in cables, transmission lines, or networks according to type of conductors in power transmission or distribution lines, e.g. overhead
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H1/00—Details of emergency protective circuit arrangements
- H02H1/0007—Details of emergency protective circuit arrangements concerning the detecting means
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Abstract
The invention provides a method and a device for protecting and identifying broken lines of a high-voltage overhead line, wherein the method comprises the following steps: acquiring current information of a protected line; judging whether the current information has a high-frequency current signal or not; if the high-frequency current signal exists, determining that the protected line works normally; if no high-frequency current signal exists, calculating a phase current amplitude according to the current information, and judging whether the protected line has a line break fault according to a comparison result of the phase current amplitude and a current setting value. The device is used for realizing the method. The method and the device can solve the technical problem that the disconnection fault of the existing high-voltage overhead line is difficult to identify under the condition of light load or no load.
Description
Technical Field
The invention relates to the technical field of relay protection of power systems, in particular to a high-voltage overhead line disconnection protection identification method.
Background
At present, high-voltage overhead lines and buildings, traffic lines and the like are crossed and spanned more, and after a line break fault occurs, if a power transmission line falls to the ground in a charged state, personal injury, shutdown of an electrified railway and other safety accidents are easily caused. Therefore, after a disconnection fault occurs, the fault line needs to be identified and cut off before falling to the ground, so that more serious damage caused by the falling of the fault line is avoided. In the process of implementing the invention, the inventor finds that the prior art has at least the following technical problems: because the probability of occurrence of the disconnection fault is small and the fault characteristic is light, the research in the related direction is insufficient at present, and the practicability of the provided method is not strong. And when the line is lightly loaded or unloaded, the electric quantity change before and after the disconnection fault is very small, so that the existing protection scheme has certain dead zones.
Disclosure of Invention
The invention aims to provide a high-voltage overhead line disconnection protection and identification method to solve the technical problem that disconnection faults of the existing high-voltage overhead line are difficult to identify under the condition of light load or no load.
In order to achieve the object of the present invention, a first aspect of the present invention provides a method for protecting and identifying a broken high-voltage overhead line, comprising the following steps:
acquiring current information of a protected line;
judging whether the current information has a high-frequency current signal or not;
if the high-frequency current signal exists, determining that the protected line works normally;
if no high-frequency current signal exists, calculating a phase current amplitude according to the current information, and judging whether the protected line has a line break fault according to a comparison result of the phase current amplitude and a current setting value.
Wherein, the judging whether the line to be protected has the line break fault according to the comparison result of the phase current amplitude and the current setting value comprises:
if the phase current amplitude is smaller than the current setting value, judging that a disconnection fault occurs;
and if the phase current amplitude is larger than or equal to the current setting value, judging that the broken line does not have fault.
The second aspect of the present invention provides another method for protecting and identifying a broken high voltage overhead line, comprising the following steps:
acquiring current information of a protected line;
calculating phase current amplitude according to the current information;
comparing the phase current amplitude value with a current setting value;
if the phase current amplitude is larger than or equal to the current setting value, determining that the protected line works normally;
if the phase current amplitude is smaller than the current setting value, judging whether the current information has a high-frequency current signal or not, and judging whether the protected line has a line break fault or not according to whether the high-frequency current signal exists or not.
Wherein the judging whether the line to be protected has the disconnection fault according to whether the high-frequency current signal exists comprises:
if the high-frequency current signal exists, determining that the protected line works normally;
if no high-frequency current signal exists, calculating a phase current amplitude according to the current information, and judging whether the protected line has a line break fault according to a comparison result of the phase current amplitude and a current setting value.
The current setting value is calculated by the following formula:
Iset＝KrelIc
wherein, Krel＝1.1～1.2，IcIs the capacitive current of the protected line.
The third aspect of the present invention further provides an apparatus for implementing the method for identifying disconnection protection of a high voltage overhead line in the first aspect, where the apparatus includes:
a relay protection device configured to acquire current information of a protected line;
a signal processing unit configured to determine whether a high-frequency current signal exists in the current information;
if the high-frequency current signal exists, determining that the protected line works normally;
if no high-frequency current signal exists, calculating a phase current amplitude according to the current information, and judging whether the protected line has a line break fault according to a comparison result of the phase current amplitude and a current setting value.
The fourth aspect of the present invention further provides an apparatus for implementing the method for identifying the disconnection protection of the high voltage overhead line according to the second aspect, including:
a relay protection device configured to acquire current information of a protected line;
a calculation unit configured to calculate a phase current magnitude from the current information;
a comparison unit configured to compare the phase current amplitude value with a current setting value;
a judging unit configured to determine that the protected line works normally in response to the phase current amplitude being greater than or equal to the current setting value; and responding to the fact that the phase current amplitude is smaller than the current setting value, judging whether the protected line has a disconnection fault according to the existence of a high-frequency current signal.
The technical scheme at least has the following beneficial effects:
when a short-circuit fault occurs on a line, the high-frequency channel is possibly disconnected due to the fact that the transmission channel has a large high-frequency attenuation, in order to avoid the short-circuit fault being mistaken for a broken-line fault, current information needs to be sampled, a current amplitude criterion is introduced, and the current amplitude is compared with a current setting value to form a current criterion. According to the technical scheme, by utilizing the characteristic that the carrier channel is disconnected when the disconnection fault occurs, the high-frequency current signal of the power carrier is connected to the relay protection device, and the disconnection fault can be identified by combining the current amplitude criterion. The method directly detects the carrier channel without being influenced by the transmission power of the line to the protection reliability, and solves the problem that the disconnection fault is difficult to identify under the condition of light load or no load.
In addition, other advantageous effects will be further explained below.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a flowchart of a method according to an embodiment of the present invention.
Fig. 2 is a structural diagram of the high-voltage overhead line system according to the first embodiment of the present invention.
FIG. 3 is a flowchart of a method according to a second embodiment of the present invention.
Elements in the figure are labeled:
1-a first equivalent power supply, 2-a first bus, 3-a protected line, 4-a second bus, 5-a second equivalent power supply, 6-a first relay protection device and 7-a second relay protection device.
Detailed Description
Various exemplary embodiments, features and aspects of the present disclosure will be described in detail below with reference to the accompanying drawings. In the drawings, like reference numbers can indicate functionally identical or similar elements. While the various aspects of the embodiments are presented in drawings, the drawings are not necessarily drawn to scale unless specifically indicated.
In addition, in the following detailed description, numerous specific details are set forth in order to provide a better understanding of the present invention. It will be understood by those skilled in the art that the present invention may be practiced without some of these specific details. In some instances, means, elements and circuits that are well known to those skilled in the art have not been described in detail so as not to obscure the present invention.
As shown in fig. 1, a first embodiment of the present invention provides a method for identifying disconnection protection of a high-voltage overhead line, which is based on a structure of the high-voltage overhead line system shown in fig. 2, and referring to fig. 2, the high-voltage overhead line system includes a first equivalent power source 1, a first bus 2, a protected line 3, a second bus 4, a second equivalent power source 5, a first relay protection device 6, and a second relay protection device 7, the first equivalent power source 1 is connected to the first bus 2, the first bus 2 is connected to the second bus 4 through the protected line 3, and the second bus 4 is connected to the second equivalent power source 5; first relay protection device 6 installs at first bus 2 exit, second relay protection device 7 installs at second bus 4 exit.
The power carrier communication is a communication method specific to a power system, and is a technology for transmitting an analog or digital signal at a high speed by a carrier method using an existing power line. The method has the greatest characteristic that data transmission can be carried out only by wires without erecting a network again.
Based on the structure of the high-voltage overhead line system, the protected line is considered to be provided with three independent high-frequency channels, and each high-frequency channel adopts a phase-ground coupling mode, wherein the working mode of the carrier channel is a normal high-frequency current mode, namely, a transmitter is in a transmitting state when in normal operation, namely, a high-frequency current signal exists. The relay protection device of the protected circuit collects current information according to a fixed sampling period, wherein the current information comprises three-phase high-frequency current information and circuit current information.
Referring to fig. 1, the method for protecting and identifying a broken high-voltage overhead line in the first embodiment specifically includes the following steps:
s11, acquiring current information of the protected line;
s12, judging whether the current information has high-frequency current signals or not; setting carrier channel availability flag bit Sφ(Φ ═ a, b, c), 1 indicates that the channel is normal, and 0 indicates that the channel is open;
s13 if there is a high frequency current signal, i.e. SφIf the protection circuit is 1, determining that the protected circuit works normally;
s14, if there is no high frequency current signal, calculating phase current amplitude value according to the current information
And according to said phase current amplitude
And current setting value IsetAnd (phi ═ a, b and c) judging whether the protected line has a line break fault or not.
Wherein, the step S14 of determining whether the line to be protected has the disconnection fault according to the comparison result between the phase current amplitude and the current setting value includes:
s141, if the phase current amplitude is smaller than the current setting value, judging that a disconnection fault occurs;
and S142, if the phase current amplitude is larger than or equal to the current setting value, judging that the disconnection does not have a fault.
For example, an a-phase disconnection fault occurs at a distance of 30% in the forward direction of the first relay protection device (f 1 in fig. 2). For the first relay protectionThe device is protected by a protecting device, and the protecting device is arranged on the protecting device,
the first relay protection device sends a tripping command to act on a local side circuit breaker to trip; with regard to the second relay protection device,
and the second relay protection device sends a tripping command to act on the circuit breaker at the side to trip, namely, the disconnection fault is removed.
For another example, the reverse outlet of the second relay protection device is set to generate an A-phase disconnection fault (f 2 in FIG. 2). Due to an out-of-range fault, the high frequency path of the protected line is normal. For the first relay protection device, SaWhen the relay protection device is not operated, the first relay protection device is not operated; for the second relay protection device, SaWhen the relay protection device is 1, the second relay protection device does not operate, that is, an out-of-range fault does not malfunction.
Specifically, when a short-circuit fault occurs in a line, a high-frequency channel may be disconnected due to a large amount of high-frequency attenuation of a transmission channel, and in order to avoid the short-circuit fault being mistakenly identified as a line-breaking fault, the method samples current information and introduces a current amplitude criterion, and compares a current amplitude with a current setting value to form the current criterion. And comprehensively judging whether the protected line is broken or not by combining the high-frequency current signal and the current criterion.
The embodiment utilizes the original power line carrier channel of the line, and realizes the identification of the disconnection fault of the high-voltage overhead line under the condition of not increasing the equipment investment.
The current setting value is a standard value which is compared with the actual current when the relay protection judges tripping, is artificially specified, and is calculated according to the bearing capacity of a circuit and a power grid.
As shown in fig. 3, a second embodiment of the present invention provides another method for protecting and identifying a broken high-voltage overhead line, including the following steps:
s21, acquiring current information of the protected line;
s22, calculating the phase current amplitude according to the current information;
s23, comparing the phase current amplitude with a current setting value;
s24, if the phase current amplitude is larger than or equal to the current setting value, determining that the protected line works normally;
s25, if the phase current amplitude is smaller than the current setting value, judging whether the current information has a high-frequency current signal, and judging whether the protected line has a disconnection fault according to whether the high-frequency current signal exists.
Wherein the step S25 of determining whether the line to be protected has a disconnection fault according to whether the high-frequency current signal exists includes:
s251, if a high-frequency current signal exists, determining that the protected line works normally;
and S252, if no high-frequency current signal exists, calculating a phase current amplitude according to the current information, and judging whether the protected line has a disconnection fault according to a comparison result of the phase current amplitude and a current setting value.
Specifically, the method described in the second embodiment is similar to the method described in the first embodiment, and the current information is sampled and a current amplitude criterion is introduced, and the current amplitude is compared with the current setting value to form the current criterion. And comprehensively judging whether the protected line is broken or not by combining the high-frequency current signal and the current criterion. Therefore, other details of the second method in the embodiment can be obtained by referring to the first method in the embodiment, and are not described herein again.
The current setting value is calculated by the following formula:
Iset＝KrelIc
wherein, Krel＝1.1～1.2，IcIs the capacitive current of the protected line.
An embodiment of the present invention further provides a device for implementing the method for identifying a high-voltage overhead line disconnection protection according to the first aspect, where the method includes:
a relay protection device configured to acquire current information of a protected line;
a signal processing unit configured to determine whether a high-frequency current signal exists in the current information;
if the high-frequency current signal exists, determining that the protected line works normally;
if no high-frequency current signal exists, calculating a phase current amplitude according to the current information, and judging whether the protected line has a line break fault according to a comparison result of the phase current amplitude and a current setting value.
It should be noted that, for the apparatus disclosed in the third embodiment, since it corresponds to the method disclosed in the first embodiment, the description is relatively simple, and for the relevant points, refer to the description of the method part.
The fourth embodiment of the present invention further provides a device for implementing the method for identifying the disconnection protection of the high voltage overhead line according to the second aspect, including:
a relay protection device configured to acquire current information of a protected line;
a calculation unit configured to calculate a phase current magnitude from the current information;
a comparison unit configured to compare the phase current amplitude value with a current setting value;
a judging unit configured to determine that the protected line works normally in response to the phase current amplitude being greater than or equal to the current setting value; and responding to the fact that the phase current amplitude is smaller than the current setting value, judging whether the protected line has a disconnection fault according to the existence of a high-frequency current signal.
It should be noted that, for the apparatus disclosed in the fourth embodiment, since it corresponds to the method disclosed in the second embodiment, the description is relatively simple, and for the relevant points, refer to the description of the method part.
It can be known from the description of the above embodiment that when a short-circuit fault occurs in a line, a high-frequency channel may be disconnected due to a lot of high-frequency attenuation of a transmission channel, and in order to avoid misidentifying the short-circuit fault as a disconnection fault, current information needs to be sampled and a current amplitude criterion is introduced, and a current amplitude is compared with a current setting value to form the current criterion. According to the technical scheme, by utilizing the characteristic that the carrier channel is disconnected when the disconnection fault occurs, the high-frequency current signal of the power carrier is connected to the relay protection device, and the disconnection fault can be identified by combining the current amplitude criterion. The method directly detects the carrier channel without being influenced by the transmission power of the line to the protection reliability, and solves the problem that the disconnection fault is difficult to identify under the condition of light load or no load.
Having described embodiments of the present invention, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen in order to best explain the principles of the embodiments, the practical application, or improvements made to the technology in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.
Claims (5)
1. A high-voltage overhead line disconnection protection and identification method is characterized by comprising the following steps:
acquiring current information of a protected line;
judging whether the current information has a high-frequency current signal or not;
if the high-frequency current signal exists, determining that the protected line works normally;
if no high-frequency current signal exists, calculating a phase current amplitude according to the current information, and judging whether the protected line has a line break fault according to a comparison result of the phase current amplitude and a current setting value, wherein if the phase current amplitude is smaller than the current setting value, the line break fault is judged to occur; if the phase current amplitude is larger than or equal to the current setting value, judging that the broken line does not have a fault; the current setting value is calculated by the following formula:
Iset＝KrelIc
wherein, Krel＝1.1～1.2，IcIs the capacitive current of the protected line.
2. A high-voltage overhead line disconnection protection and identification method is characterized by comprising the following steps:
acquiring current information of a protected line;
calculating phase current amplitude according to the current information;
comparing the phase current amplitude value with a current setting value; the current setting value is calculated by the following formula:
Iset＝KrelIc
wherein, Krel＝1.1～1.2，IcIs the capacitance current of the protected line;
if the phase current amplitude is larger than or equal to the current setting value, determining that the protected line works normally;
if the phase current amplitude is smaller than the current setting value, judging whether the current information has a high-frequency current signal or not, and judging whether the protected line has a line break fault or not according to whether the high-frequency current signal exists or not.
3. The method for identifying the disconnection protection of the high-voltage overhead line according to claim 2, wherein the judging whether the disconnection fault of the protected line occurs according to the existence of the high-frequency current signal comprises:
if the high-frequency current signal exists, determining that the protected line works normally;
if no high-frequency current signal exists, calculating a phase current amplitude according to the current information, and judging whether the protected line has a line break fault according to a comparison result of the phase current amplitude and a current setting value.
4. An apparatus for implementing the method for identifying high-voltage overhead line disconnection protection of claim 1 or 2, comprising:
a relay protection device configured to acquire current information of a protected line;
a signal processing unit configured to determine whether a high-frequency current signal exists in the current information;
if the high-frequency current signal exists, determining that the protected line works normally;
if no high-frequency current signal exists, calculating a phase current amplitude according to the current information, and judging whether the protected line has a line break fault according to a comparison result of the phase current amplitude and a current setting value.
5. An apparatus for implementing the method for identifying high-voltage overhead line disconnection protection of claim 2 or 3, comprising:
a relay protection device configured to acquire current information of a protected line;
a calculation unit configured to calculate a phase current magnitude from the current information;
a comparison unit configured to compare the phase current amplitude value with a current setting value;
a judging unit configured to determine that the protected line works normally in response to the phase current amplitude being greater than or equal to the current setting value; and responding to the fact that the phase current amplitude is smaller than the current setting value, judging whether the protected line has a disconnection fault according to the existence of a high-frequency current signal.
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| CN110794340B (en) * | 2019-11-13 | 2022-06-14 | 深圳供电局有限公司 | Disconnection protection method and circuit for high-voltage overhead line |
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| JPS59143972A (en) * | 1983-02-07 | 1984-08-17 | Furukawa Electric Co Ltd:The | Monitoring method of power transmission line |
| JPH02155192A (en) * | 1988-12-06 | 1990-06-14 | Matsushita Electric Ind Co Ltd | Microwave oven |
| CN2929734Y (en) * | 2006-06-15 | 2007-08-01 | 杭州瑞琦信息技术有限公司 | Theft detector for live cable |
| CN202256549U (en) * | 2011-08-06 | 2012-05-30 | 深圳市核达中远通电源技术有限公司 | Broken line detection circuit for high voltage transmission lines |
| CN102879711A (en) * | 2012-09-29 | 2013-01-16 | 江苏省电力公司徐州供电公司 | Method for quickly positioning and monitoring faults of power distribution network |
| CN103344869B (en) * | 2013-06-20 | 2015-08-12 | 山东大学 | A kind of wire break alarm device and alarm method being applicable to 6 ~ 35kV power distribution network |
| CN204495948U (en) * | 2015-04-16 | 2015-07-22 | 王金泽 | A kind of disconnection monitor |
| CN105375451B (en) * | 2015-12-21 | 2017-11-28 | 上海交通大学 | MMC HVDC DC line monopolar grounding fault guard methods based on current waveform identification |
| CN106501668B (en) * | 2016-03-16 | 2019-06-28 | 国网山东省电力公司济宁供电公司 | A kind of conventional electrical distribution net single-phase wire break fault-line selecting method |
| CN106711965B (en) * | 2016-12-08 | 2019-03-26 | 南京南瑞继保电气有限公司 | A kind of transmission line of electricity broken string method of discrimination based on semaphore transmitting |
| CN107632240B (en) * | 2017-09-08 | 2020-04-21 | 河北金能电力科技股份有限公司 | Overhead cable current data primary analysis method, health state monitoring method and system |
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