CN113608070A - Single-phase earth fault area judgment method of node zero sequence current comparison method - Google Patents

Single-phase earth fault area judgment method of node zero sequence current comparison method Download PDF

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CN113608070A
CN113608070A CN202110900965.6A CN202110900965A CN113608070A CN 113608070 A CN113608070 A CN 113608070A CN 202110900965 A CN202110900965 A CN 202110900965A CN 113608070 A CN113608070 A CN 113608070A
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node
fault
current
sequence current
zero sequence
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李景禄
李政洋
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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
    • G01R31/088—Aspects of digital computing
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y04—INFORMATION OR COMMUNICATION TECHNOLOGIES HAVING AN IMPACT ON OTHER TECHNOLOGY AREAS
    • Y04S—SYSTEMS INTEGRATING TECHNOLOGIES RELATED TO POWER NETWORK OPERATION, COMMUNICATION OR INFORMATION TECHNOLOGIES FOR IMPROVING THE ELECTRICAL POWER GENERATION, TRANSMISSION, DISTRIBUTION, MANAGEMENT OR USAGE, i.e. SMART GRIDS
    • Y04S10/00—Systems supporting electrical power generation, transmission or distribution
    • Y04S10/50—Systems or methods supporting the power network operation or management, involving a certain degree of interaction with the load-side end user applications
    • Y04S10/52—Outage or fault management, e.g. fault detection or location

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Abstract

The invention discloses a power distribution network single-phase earth fault area isolation method based on a node zero current comparison method, which judges whether a node is a normal node or a fault current passing through the node by calculating capacitance current of a transformer substation and capacitance current of each feeder line according to capacitance current of a power distribution network, and comparing zero sequence current flowing through each node of a fault feeder line with zero sequence current at the head end of the fault feeder line when single-phase earth occurs, thereby judging the fault area.

Description

Single-phase earth fault area judgment method of node zero sequence current comparison method
Technical Field
The invention mainly belongs to the field of distribution line fault area isolation, and relates to an area judgment method for a single-phase earth fault of a distribution line, which is used for solving the problem of distribution network fault area isolation, reducing the power failure range and achieving the purposes of ensuring the safety of a power grid and improving the power supply reliability.
Background
When a single-phase earth fault occurs in the power distribution network, the zero sequence current flowing through the head end of the fault line is the sum of the capacitance currents of the other feeder lines, and the zero sequence current flowing through the head end of the non-fault line is the capacitance current of the line to earth; zero sequence current flowing through each node in the fault line is the sum of capacitance currents of other feeder lines and the capacitance current to ground of the line at the front part of the node; the zero sequence current flowing through each node of the non-fault line is the capacitance current of the back line of the node to ground.
For the overhead cable mixed line, the zero sequence current of each node can be influenced by the structure and the branch of the line and the capacitance current of the power consumer on the distribution line. When a single-phase earth fault occurs in a power distribution network, zero-sequence current flows through a fault line or a non-fault line, and the zero-sequence current flowing through each node of the power distribution line is subjected to sudden change under the influence of factors such as a line structure, user scale and the like.
The single-phase earth fault of the distribution line is grounded through a transition resistor, a single-phase low-resistance earth fault and a single-phase high-resistance earth fault exist according to the difference of the transition resistor, the zero sequence current flowing through each node is different due to the difference of the transition resistor, the zero sequence current is smaller when the line breaking and high-resistance earth fault occurs, but the fault needs to be isolated in time due to the larger influence on personal safety.
The intelligent switch with the secondary fusion is installed on the distribution line, the purpose is to perform regional isolation according to the region where the fault occurs when the power distribution network has the fault, but the complexity of zero sequence current distribution flowing through each node of the fault feeder line and the non-fault feeder line causes difficulty in judging the fault region, so that the intelligent switch cannot be accurately used for performing regional isolation on the single-phase earth fault.
Therefore, a method for solving the distribution law of zero-sequence current flowing through each node of a fault feeder line and a non-fault feeder line under complex working conditions and judging a fault area is found, and the area isolation of the single-phase earth fault is very necessary.
Disclosure of Invention
In order to solve the problems, the invention provides a single-phase earth fault area judgment method of a node zero sequence current comparison method, which is used for calculating the total earth capacitance current I of a single power supply substation power distribution network with a k return lineCCapacitive earth current I of each feederiCFinding the maximum capacitance-to-ground current in the feeder
Figure 366842DEST_PATH_IMAGE001
Comparing the maximum capacitance-to-ground current of the feeder
Figure 369564DEST_PATH_IMAGE001
Whether or not:
Figure 800545DEST_PATH_IMAGE002
if not, the bus is connected with a grounding compensation capacitor with a certain capacity to meet the requirement.
When the grounding fault processing and grounding line selection device judges that the phase permanent grounding fault occurs in the feeder line m, the zero sequence current flowing through the head end of the fault feeder line m is detected firstly
Figure 163393DEST_PATH_IMAGE003
The result of the grounding line selection and the collected zero sequence current of the head end of the fault feeder line m are compared
Figure 481373DEST_PATH_IMAGE003
Uploading to the background of the intelligent switch, and convecting through each node in the feeder m by the background of the intelligent switch
Figure 638685DEST_PATH_IMAGE004
Zero sequence current of
Figure 556963DEST_PATH_IMAGE005
Detecting the detected node zero sequence current
Figure 205725DEST_PATH_IMAGE005
Zero sequence current with head end of fault feeder line
Figure 893059DEST_PATH_IMAGE003
Make a comparison if
Figure 221272DEST_PATH_IMAGE006
Then node
Figure 361266DEST_PATH_IMAGE004
The fault current passes through the node, namely a single-phase earth fault point is arranged on the rear side (load side) of the node; if it is
Figure 816649DEST_PATH_IMAGE007
Then node
Figure 624068DEST_PATH_IMAGE004
The node is a normal node, namely a single-phase earth fault point is arranged on the front side (power supply side) of the node; and the area where the single-phase earth fault occurs is between the adjacent fault current crossing node and the normal node.
When a branch line is arranged in a single-phase earth fault area and a node intelligent switch is arranged on the branch line, checking and judging the node zero sequence current of the branch line to judge whether a fault occurs on the branch line;
if node S1The single-phase earth fault area is between the outgoing switch and the first node when the node is detected and judged to be a normal node.
Each node intelligent switch of the feeder line has the function of communicating zero-sequence current collection and the background, and the collected node zero-sequence current can be quickly uploaded to the background of the intelligent switch when a fault occurs.
The normal node is that the rear side (load side) of the node has no single-phase earth fault point, and no fault current flows in the node; the fault current cross node is a single-phase earth fault point on the rear side (load side) of the node, and fault current flows through the node.
The method is not suitable for a power distribution network with the grounded arc suppression coil, and if the power distribution network with the grounded arc suppression coil needs to change the grounded arc suppression coil into a dynamic grounding mode and switch the mode into a resistance grounding mode or a non-grounding mode.
The additional arrangement of the ground compensation capacitor is that the maximum capacitance current to ground of the feeder line
Figure 123183DEST_PATH_IMAGE001
Satisfies the following conditions:
Figure 750473DEST_PATH_IMAGE008
only then, the capacitor current compensated by the grounding capacitor is satisfied
Figure 478389DEST_PATH_IMAGE009
I.e. not too much compensation, otherwise the fault handling is affected.
The invention has the following advantages:
1. the invention solves whether the earth fault exists behind the node by utilizing a node zero sequence current comparison method, and can effectively judge the distribution condition of the fault current.
2. The invention simplifies the definition of the single-phase earth fault area by defining normal nodes and fault current passing through nodes.
3. The method provided by the invention is suitable for judging the low-resistance grounded fault area and also suitable for judging the high-resistance grounded fault area; the method is suitable for ungrounded power grids and resistance grounded power grids, and has wide applicability.
4. The invention simplifies the complex problems, has strong operability and is convenient for field implementation.
Drawings
Fig. 1 is a schematic diagram of distribution line node distribution.
Detailed Description
Calculating total grounding capacitance current I of single power supply substation power distribution network with k outgoing linesCCapacitive earth current I of each feederiCFinding the maximum capacitance-to-ground current in the feeder
Figure 405894DEST_PATH_IMAGE001
Comparing the maximum capacitance-to-ground current of the feeder
Figure 75909DEST_PATH_IMAGE001
Whether or not:
Figure 737966DEST_PATH_IMAGE002
if not, the bus is connected with a grounding compensation capacitor with a certain capacity to meet the requirement.
When the grounding fault processing and grounding line selection device judges that the phase permanent grounding fault occurs in the feeder line m, the zero sequence current flowing through the head end of the fault feeder line m is detected firstly
Figure 518840DEST_PATH_IMAGE003
The result of the grounding line selection and the collected zero sequence current of the head end of the fault feeder line m are compared
Figure 42795DEST_PATH_IMAGE003
Uploading to the background of the intelligent switch, and convecting through each node in the feeder m by the background of the intelligent switch
Figure 414870DEST_PATH_IMAGE004
Zero sequence current of
Figure 16753DEST_PATH_IMAGE005
Detecting the detected node zero sequence current
Figure 352051DEST_PATH_IMAGE005
Zero sequence current with head end of fault feeder line
Figure 988568DEST_PATH_IMAGE003
Make a comparison if
Figure 387DEST_PATH_IMAGE006
Then node
Figure 823986DEST_PATH_IMAGE004
The fault current passes through the node, namely a single-phase earth fault point is arranged on the rear side (load side) of the node; if it is
Figure 962975DEST_PATH_IMAGE007
Then node
Figure 188420DEST_PATH_IMAGE004
The node is a normal node, namely a single-phase earth fault point is arranged on the front side (power supply side) of the node; and the area where the single-phase earth fault occurs is between the adjacent fault current crossing node and the normal node.
When a branch line is arranged in a single-phase earth fault area and a node intelligent switch is arranged on the branch line, checking and judging the node zero sequence current of the branch line to judge whether a fault occurs on the branch line;
if node S1The single-phase earth fault area is between the outgoing switch and the first node when the node is detected and judged to be a normal node.
Each node intelligent switch of the feeder line has the function of communicating zero-sequence current collection and the background, and the collected node zero-sequence current can be quickly uploaded to the background of the intelligent switch when a fault occurs.
The normal node is that the rear side (load side) of the node has no single-phase earth fault point, and no fault current flows in the node; the fault current cross node is a single-phase earth fault point on the rear side (load side) of the node, and fault current flows through the node.
The method is not suitable for a power distribution network with the grounded arc suppression coil, and if the power distribution network with the grounded arc suppression coil needs to change the grounded arc suppression coil into a dynamic grounding mode and switch the mode into a resistance grounding mode or a non-grounding mode.
The additional arrangement of the ground compensation capacitor is that the maximum capacitance current to ground of the feeder line
Figure 371139DEST_PATH_IMAGE001
Satisfies the following conditions:
Figure 963926DEST_PATH_IMAGE008
only then, the capacitor current compensated by the grounding capacitor is satisfied
Figure 890293DEST_PATH_IMAGE009
I.e. not too much compensation, otherwise the fault handling is affected.
The above description is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments, and all technical solutions belonging to the idea of the present invention belong to the protection scope of the present invention. It should be noted that modifications and embellishments within the scope of the invention may occur to those skilled in the art without departing from the principle of the invention, and are considered to be within the scope of the invention.

Claims (5)

1. A single-phase earth fault area judgment method of a node zero sequence current comparison method is characterized by comprising the following steps: calculating total grounding capacitance current I of single power supply substation power distribution network with k outgoing linesCCapacitive earth current I of each feederiCFinding the maximum capacitance-to-ground current in the feeder
Figure 789077DEST_PATH_IMAGE001
Comparing the maximum capacitance-to-ground current of the feeder
Figure 424589DEST_PATH_IMAGE001
Whether or not:
Figure 222781DEST_PATH_IMAGE002
if not, connecting a certain capacity of ground compensation capacitor on the bus to meet the requirement;
when the grounding fault processing and grounding line selection device judges that the phase permanent grounding fault occurs in the feeder line m, the zero sequence current flowing through the head end of the fault feeder line m is detected firstly
Figure 952839DEST_PATH_IMAGE003
The result of the grounding line selection and the collected zero sequence current of the head end of the fault feeder line m are compared
Figure 166259DEST_PATH_IMAGE003
Uploading to the background of the intelligent switch, and convecting through each node in the feeder m by the background of the intelligent switch
Figure 956360DEST_PATH_IMAGE004
Zero sequence current of
Figure 976269DEST_PATH_IMAGE005
Detecting the detected node zero sequence current
Figure 526330DEST_PATH_IMAGE005
Zero sequence current with head end of fault feeder line
Figure 846453DEST_PATH_IMAGE003
Make a comparison if
Figure 541876DEST_PATH_IMAGE006
Then node
Figure 330972DEST_PATH_IMAGE004
The fault current passes through the node, namely a single-phase earth fault point is arranged on the rear side (load side) of the node; if it is
Figure 402833DEST_PATH_IMAGE007
Then node
Figure 577462DEST_PATH_IMAGE004
The node is a normal node, namely a single-phase earth fault point is arranged on the front side (power supply side) of the node; the area where the single-phase earth fault occurs is between the adjacent fault current crossing node and the normal node;
when a branch line is arranged in a single-phase earth fault area and a node intelligent switch is arranged on the branch line, checking and judging the node zero sequence current of the branch line to judge whether a fault occurs on the branch line;
if node S1The single-phase earth fault area is between the outgoing switch and the first node when the node is detected and judged to be a normal node.
2. The method for judging the single-phase earth fault area by using the node zero sequence current comparison method according to claim 1, wherein the method comprises the following steps: each node intelligent switch of the feeder line has the function of communicating zero-sequence current collection and the background, and the collected node zero-sequence current can be quickly uploaded to the background of the intelligent switch when a fault occurs.
3. The method for judging the single-phase earth fault area by using the node zero sequence current comparison method according to claim 1, wherein the method comprises the following steps: the normal node is that the rear side (load side) of the node has no single-phase earth fault point, and no fault current flows in the node; the fault current cross node is a single-phase earth fault point on the rear side (load side) of the node, and fault current flows through the node.
4. The method for judging the single-phase earth fault area by using the node zero sequence current comparison method according to claim 1, wherein the method comprises the following steps: the method is not suitable for a power distribution network with the grounded arc suppression coil, and if the power distribution network with the grounded arc suppression coil needs to change the grounded arc suppression coil into a dynamic grounding mode and switch the mode into a resistance grounding mode or a non-grounding mode.
5. The method for judging the single-phase earth fault area by using the node zero sequence current comparison method according to claim 1, wherein the method comprises the following steps: the additional arrangement of the ground compensation capacitor is that the maximum capacitance current to ground of the feeder line
Figure 460099DEST_PATH_IMAGE001
Satisfies the following conditions:
Figure 454600DEST_PATH_IMAGE008
only then, the capacitor current compensated by the grounding capacitor is satisfied
Figure 595731DEST_PATH_IMAGE009
I.e. not too much compensation, otherwise the fault handling is affected.
CN202110900965.6A 2021-08-06 2021-08-06 Single-phase earth fault area judgment method of node zero sequence current comparison method Pending CN113608070A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114217172A (en) * 2021-12-16 2022-03-22 国网湖北省电力有限公司孝感供电公司 Power distribution network single-phase earth fault area judgment method based on node identification
CN114609468A (en) * 2021-12-16 2022-06-10 国网湖北省电力有限公司孝感供电公司 Power distribution network single-phase earth fault interval discrimination method based on cloud edge terminal cooperation

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114217172A (en) * 2021-12-16 2022-03-22 国网湖北省电力有限公司孝感供电公司 Power distribution network single-phase earth fault area judgment method based on node identification
CN114609468A (en) * 2021-12-16 2022-06-10 国网湖北省电力有限公司孝感供电公司 Power distribution network single-phase earth fault interval discrimination method based on cloud edge terminal cooperation
CN114609468B (en) * 2021-12-16 2023-12-05 国网湖北省电力有限公司孝感供电公司 Cloud edge end cooperation-based single-phase earth fault interval distinguishing method for power distribution network

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